# Dsavitsk/Beezar Torpedo Build Thread



## tomb

While I'm still working on getting the kits and website ready, I thought I'd post a build thread for the Dsavitsk/Beezar Torpedo amp.
   
  To review just a bit, the Torpedo is the latest iteration of Dsavitsk's parafeed designs known as the L'ess Pressivo. There are many links that chronicle the evolution of the basic design on Dsavitsk's excellent DIY website:
  http://www.ecp.cc/less-pressivo.html
  http://www.ecp.cc/less-pressivo-build.html
  http://www.ecp.cc/less-pressivo-plus.html http://www.ecp.cc/less-pressivo-plus-plus.html
   
  In my layman's terms, the design is a great representation of a true, high-voltage, transformer-coupled, tube headphone amplifier. One of Dsavitsk's design goals was low cost, too.
   
  After a time, I challenged Dsavitsk to bring one of the L'ess Pressivo designs to a fully PCB-based construction. Little did I know that after a quick successful backboard build, the final implementation became perhaps the longest development and prototyping periods for a DIY headphone amp. The reasons are many, but the result is that the design is already quite refined.  The Torpedo is the culmination of that work.
   
  The Torpedo is fully PCB-based with no wiring needed, save a ground wire for the Alps pot and a safety ground wire from the PCB to the case. It uses readily available components, including tubes that run about $2 and less (6J6 - the 6V heater version of the Starving Student tubes). The only exception to that are the custom power and output transformers and a custom-designed case that requires no drilling/cutting. (BTW - most tube dealers say the 6J6 runs into the tens of thousands in stock, so no running out as happened with the 19J6.)
   
  Enough of that, here goes - Pictured below you see the PCB. Yes, it's long. It was done that way to get the power transformer as far away as possible from the output transformers - to reduce any tendency toward hum.



   
  You can also see above, some of the tools that I use to populate a PCB -

 A nice, flat piece of high-quality pine used as the building board,
 My trusty Hakko 936,
 and brass wool to keep the Hakko tip's clean.
   
  Some of the other tools I use when soldering a PCB:



   

 Smooth jaw needle-nose pliers (keeps the marks off of those part leads),
 Flush cutters (for keeping the PCB bottom clean and trim),
 A lead-bending jig,
 Wire cutters/strippers,
 Scissors for cutting parts packs, etc.,
 A Leatherman for those unforseen quick tool needs,
 De-soldering wick, and
 Finally, Kester eutectic (63-37) solder.
  Your tools may vary, but I find these pretty much cover all my needs for most PCB's.


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## tomb

The full building sequence will be posted on the upcoming Torpedo website, but generally speaking, it follows the standard lowest-to-tallest-part construction sequence.
   
*Step 1:*
  Install the lowest profile electronic part, the D9 diode.  (The BOM on the upcoming website will fully detail each part.)  I actually made a mistake and forgot this until later on in my build, but it should be first:



   
*Step 2.*
  Next, install the low-profile resistors.  These include R1,R6,R7,R8,R9,R10,R11,R12, and R13.  The Torpedo PCB was designed to make the greatest use of available parts, so the pads are larger than the standard resistors spec'd in the BOM.  I find it helpful in those cases to use a lead-bending jig as shown here:



   
  Next, place all the resistors - with their leads bent - in the proper locations and solder into place.  This is straightforward and no different than any other design.  However ... since the Torpedo PCB uses heavyweight 2oz. copper for the ground plane and the fact that it is 14" long in one direction, you may find that the ground pads have a tendency to "sink" the heat from your solder tip pretty quickly.  IOW, you may have some difficulty in soldering the ground pads.  That's OK - the holes are all through-plated.  Nevertheless, due to the high-voltage characteristics of the amp, I recommend that you ensure proper wicking to the top side of the PCB for all joints.  If necessary on the ground plane pads, please turn the PCB over and add additional solder as needed to ensure a good connection to the ground plane:



   
  And here we have all of the low-profile resistors soldering in place:


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## tomb

*Step 3. -*
  Install the High-Voltage rectifiers, D1, D2, D3, and D4.  These are pretty neat little devils.  They're encapsulated in glass.  Again, the voltage they will be handling could be close to 300 volts, so please ensure that your solder connections are hot, clean and fully wicked to the top side of the PCB.  As with the above, please turn the PCB over and add solder (and heat) as necessary to complete the ground plane connections on the top side - if needed:



   
*Step 4. -*
  Install the higher-profile resistors - R2, R3, R4, and R5.  These are shown in the pic below:
   
*UPDATE!!Please install the Hammond #154H choke instead of using R2!*
   



  BTW, you will notice some jumpers at the top of the pic.  We'll install these in Step 5.  One might wonder, seeing as how the jumpers are just about as low a profile part as you can get on a through-hole PCB, why did we wait until Step 5?  Simple - installing the resistors first gives us all of those spent leads that we can pick from to make the jumpers.  At the same time, the board is long enough and the resistor parts are low enough that it doesn't create much of a problem installing the jumpers after the resistors.
   
  A note about R2: There is an option to use a choke at this position, instead.  After the extensive prototyping we did, I think the general consensus is that the choke may have caused the introduction of some hum, so we went with the resistor option.  You are welcome to try the choke - the opinions were far from conclusive and the resistor is an easy enough swap-out.  On paper, the choke should be superior and it's possible that the hum/ripple came from the tubes.  We've found that the 6J6 can operate seemingly fine, but can produce ripple if the tube is not completely up to snuff.  So, your choice, but we'll stick with the resistor for this build.
   
*Step 5. -*
  Install the jumpers for the power transformer.  The power transformer is made to use either 120V or 240V input.  For 120V, simply jumper "A" to "B" and "C" to "D."  This is shown in the pic:



  Again, good solder joints are called for and be sure you get wicking to the top side.  Remember that this amp uses high-voltage.  Build correctly and cleanly, you will never have an issue.  BTW, international folks who will use 240V input will solder "B" to "C."


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## tomb

*Step 6. -*
  Install the Low-Voltage rectifiers - D5, D6, D7, and D8.  These form the basis of the heater supply and while the eventual voltage is only ~6VDC, the current for two 6J6 tubes is quite high.  Hence, the use of the large, Schottky barrel rectifiers.  Those of you who've built a MiniMAX or MOSFET-MAX are probably familiar with these.  Straightforward in installations, bend the leads and solder them in place:



   
*Step 7. -*
  Install the C5 capacitor.  No polarity is needed on this one:



   
   
*Step 8. -*
  Install the LEDs - D10, D11, D12, D13, D14, and D15.  No, these aren't tube lights.  Dsavitsk uses a fairly unique solution with LEDs forming the basis of both the CCS (Constant Current Source) and Tube Bias.  Both of these will be explained in detail on the Torpedo website, but suffice to say that not any 'ol LED will work.  The proper LEDs are still plentiful and cheap, but any substitution must be carefully researched for the proper voltage/current relationship.  We recommend you stay with the specified LEDs unless otherwise noted.  Install with the long lead in the pads marked "+":


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## tomb

*Step 9. -*
  Install the TO-92 transistors, Q1, Q2, Q3, and Q4.  Two of these transistors are used in the CCS's, while the other two form part of the unique transistor-based tube bias (full explanation on the Torpedo website).  These transistors are familiar to Millett/MiniMAX/MOSFET-MAX builders and are the ubiquitous 2N5087's.  I matched mine, but only because I had them that way from MAX kits. 
	

	
	
		
		

		
			







   
  At this point, you can install the optional capacitors C7 and C8.  I didn't install them and haven't missed them in a previous prototype build.  So, my next step is installing the C6 capacitor:
   
*Step 10. -*
  Install the C6 capacitor.  This is the small electrolytic capacitor that forms part of the circuit for the regulated heater supply:



  Oops!  You can see a mistake I made: installing the C9 and C10 capacitors (those red Wima's).  Not a big problem, but the next step should be installing the impedance switch.
   
*Step 11. -*
  Install the impedance switch.  This is a mechanical/electrical connection, so ensure that the solder joints are properly wicked to the top side of the PCB and that the pads are fully-filled with solder:



  Note the wicking up along the leads.  Also, do not forget to solder the tabs of the front plate of the switch.  As with all three components at the front of the PCB (volume pot, headphone jack, impedance switch), take care to line everything up and ensure that the part is flush against the PCB.  The reason I use a pine board as my PCB building board is so that I turn the PCB over and apply pressure to the bottom of the PCB while soldering the leads.  This ensures that the parts are flush.
   
  Oops!  Dsavitsk snuck this one in on me - there are jumpers in the signal traces to the pot if you wish to wire in a different pot or attenuator.  We're sticking with the venerable Alps Blue Velvet (RK27), so we'll solder in jumpers for these:



   
*Step 12. -*
  We'll ignore my mistake in jumping the gun on the Wima's and you should properly solder them in as Step 12:



   
  We'll start out with the tube sockets in Step 13. tomorrow!


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## tomb

*Step 13. -*
  Tube sockets!  No drilling for tube lighting here, though - too many high-voltage traces running under the sockets.  That's OK, though, because the amp's PCB already has six LEDs that we installed in Step 8.
   
  We recommend the oft-used ceramic PCB tube sockets for the Torpedo as shown below - one wrapped as they come from the manufacturer and one unwrapped:



  Inspect your tube sockets carefully.  I've seen some where the tube-pin holes were partially or completely covered by the molded ceramic.
   
  Next, I install my tube sockets a little differently than many.  The sockets, their structural integrity, alignment and proper electrical connection are all important.  You may end up plugging and un-plugging different tubes tens or perhaps hundreds of times.  The sockets need to mounted properly to withstand that kind of fatigue.  The electrical connection must be sound to minimize the effects of grounding issues.  Finally, their alignment is also important to prevent permanently crooked tubes for the life of the amp.  De-soldering one of these buggers is difficult, so proper preparation is key.
   
  So, I start by splaying out the sockets' PCB pins so that the circle they form is slightly over-sized compared to the PCB pads.  Looking at the pic below, you can see that the PCB pins are bent outward so that they're just outside the PCB pads:



  IMHO, this forces you to slightly wedge the pins back inward, so that the fit is tight and secure - everything is pretty much locked into place before you apply the first solder.
   
  Here we can see both sockets with their PCB pins splayed out, just prior to placing into the PCB and soldering into place:



   
  Finally, solder them into the PCB.  As with previous mechanical-electrical solder connections, ensure that the pads are completely filled and that you get wicking some distance up the pins on the top side of the PCB:



  Note that the solder has wicked up at least 1/8" or so on each PCB pin leg.  Turn the PCB over and apply solder to the top, if necessary, to ensure a good mechanical connection.  While soldering on the backside of the PCB, treat the sockets as if you're tightening bolts on a spare tire - alternate soldering opposite pins until you've completed the circle.


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## tomb

*Step 14. -*
  Install the headphone jack.  This is pretty standard, as most of you should've installed a headphone jack before.  However, please note earlier instructions to keep the parts flush against the top surface of the PCB and aligned.  The Torpedo front plate has little play and there is no flexibility in adjusting the position of soldered-in parts.



  This is another mechanical-electrical connection, so again - try to make certain that the solder joints wick up the top side of the PCB and the headphone jack pins.  If you have trouble with the ground pins (the ones in front indicated by the arrow), then solder some on the top side - but be careful!  The body of the headphone jack is plastic and it _will_ melt!
   
*Step 15. -*
  Install the C1 capacitor as shown:



   
*Step 16. -*
  Install the Alps Blue Velvet pot (RK27).  Be careful here ... the pot should be aligned so that the pot shaft is perpendicular to the front edge of the PCB.  There is some play in the PCB pads.  Solder one joint on the back side and then turn the PCB over.  Check for pot shaft alignment.  You don't want to have a crooked volume knob for the life of the amp.  Use a draftsman's triangle, multiple eyeball views, whatever - just try to get it straight:


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## tomb

*Step 17. -*
  Next are the Output Transformers (OTs).  These are custom-designed/specified by Dsavitsk and fabricated by Edcor:



  Note a couple of things here ... the pins on the left in the photo above are closer together than the pins on the other side of the transformer.  This is what keys the transformers in place on the PCB.  You can't get them in backwards unless you seriously force something into damage.  Also take note of the plastic pins.  When you go to solder the transformers in place, you will not be able to get them flush to the PCB - only the pins.  So when you look sideways at the transformer and PCB, there will be a gap between the blue plastic skids and the PCB.  This is normal.
   
  Prior to placing the transformers on the PCB and soldering them in place, give them a shot of compressed air or similar.  The transformers are packed in closed-cellular foam and bits of the foam may get in-between the pins and/or the blue skids and the metal laminations.  The bits of foam will stink to high heaven when you solder the pins (maybe a bad gas of some sort), so you'll thank yourself for getting them clean of the foam bits prior to installation:



   
  Place the transformers in their positions on the PCB.  Locate the two close pins highlighted in the first pic above, and place those in the two close pads on the PCB.  I do this by placing them on the PCB, picking up and turning over the pine building board, placing it on top of the OT's, and then turning over the whole assembly so that it looks like the pic below.
   
   
  Both Left and Right channel OTs are the same.  The only thing that differentiates the Left from the Right are the traces on the PCB.  The pads are marked below.  As noted previously, the transformer skids are blue plastic and they *will* melt.  So, solder completely, but quickly.  Alternate sides to keep one blue skid cooling while you're soldering the other one.  Apply some decent pressure to the PCB so that at least the transformers are flush with the blue locating pins shown in the first pic above.



   
  Once soldered in place, they'll look like this:



  Note that the PCB assembly will be quite lopsided in weight after this.  Please handle the assembly carefully from here until its finished.  You don't want to bend the PCB too much or put a lot of torque on the traces underneath.
   
  Next up are the parafeed capacitors.  I don't actually have this labeled as a separate step, because their position in the build sequence will vary considerably, depending on which capacitors you purchase.  I used the Clarity SA caps (obtained from Madisound), which are some of the largest you can install in the Torpedo.  So, their installation came after just about everything but the very largest parts.



  Note that the Clarity caps come with some pretty long leads.  Trim/strip the insulation as shown so that the leads are exposed at the point where the cap will be flush against the top surface of the PCB.  Place them in the most convenient pads (there are several to pick from, depending on the size of the caps) and solder in place.
   
  Here they are installed:



   
  Just to give an intermediate perspective, here's a pic of a very lopsided assembly at the moment:



  As noted previously, keep the PCB properly supported at this point and use caution in moving it around. Saying that it's nose-heavy at this point is a big understatement!


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## tomb

*Step 18. -*
  Next up are the large transistors and their heat sink assemblies.  There are three - one each for the Left and Right CCS circuit and one for the heater supply voltage regulator.  Here we see some heat sink kits and a couple of the 1-1/2" tall heat sinks that are recommended:



  Note the VR1 heater supply voltage regulator.  Each heat sink comes with three holes, so there's a decision that has to be made about which hole to use to mount the transistor/IC.  The top hole leaves too little leads to solder into the PCB, while the lowest hole has the widest part of the leads below the top surface of the PCB (into the pads, IOW).  So, the middle hole was chosen.  The CCS transistors are not so straightforward in this decision.  It's possible to locate them on the lowest hole, but that will cover some of the slot cutout in the heat sink (used for additional cooling by providing venting).  So, the middle hole is chosen for those transistors as well, keeping everything consistent.
   
  Here are the three assemblies made up and ready to install on the PCB:



  See the details on heat sink mounting on the Torpedo website.  Essentially for each mounting, you have the following:

 socket head cap screw
 washer
 transistor/IC
 thermal pad
 heat sink
 washer
 lock washer
 nut
  As noted before, those slots in the bottom of the heat sink are intended for additional cooling by providing a vent around the transistor.  So, trim the thermal pads before sticking on so that they do not partially cover those slots.  Also, like the car tire analogy mentioned above, you want these finger-tight, only.  Wait until you get them soldered into the PCB before you torque down on the screws/nuts.  Torque is probably too strong a word, though, because you want to tighten them so that the lock washer is obviously compressed, but not enough so that the thermal pads get cut.  There is high-voltage going through the CCS transistors, so you don't want them shorting to the heat sink.
   
  Here we have them placed on the PCB, the PCB flipped over so that you can apply pressure to the PCB/heat sinks - ensuring a flush fit - and supported on the nose-heavy end.  Notice the curve of the PCB, regardless:



  Start with the transistor pins, first.  Alternate from one pin on one transistor to another pin on another transistor, then repeat until all of the pins are soldered.  This allows each transistor some time to cool while you're soldering the other two.  When the pins are soldered, then solder one heat sink pin each.  Flip the PCB over for a gut-check on alignment.  If OK, then flip back over and solder the remaining pin on each heat sink.
   
  Here we see the heat sinks and their transistors completely installed:


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## HiGHFLYiN9

TomB, is this little area here designated for a choke? The Torpedos I've seen so far haven't used anything here other than the resistor. 
   

  Quote: 





tomb said:


> Yep - this was mentioned in Post #3, starting with the paragraph, "A note about R2: ..."


 
 Whoops, sorry about that Tom. I was too busy looking at the pretty pictures  ​


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## dsavitsk

Yes, you can use either a resistor or a choke (not both). While a choke does a better job of smoothing the PS than a resistor, it is not clear that this is necessary as the CCS plate loads offer very good ripple rejection. The choke also seems to induce noise elsewhere and in the end may do more harm than good. However, it does eliminate HF noise generated by the diodes that might be more likely to sneak past the CCS. It is really up to the builder to decide whether or not to use it.


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## tomb

Quote: 





highflyin9 said:


> TomB, is this little area here designated for a choke? The Torpedos I've seen so far haven't used anything here other than the resistor.


 
  Yep - this was mentioned in Post #3, starting with the paragraph, "A note about R2: ..."


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## tomb

*Step 19. -*
  Next, we install the big caps - C2, C3, both of which are measly little 220uf, but the important factor is that they're *400V*!  Hence, their size. 
	

	
	
		
		

		
		
	


	




  I don't know about most of you guys/gals, but this was my first experience at large electrolytic, "snap-in" capacitors.  My whole DIY career, I've looked for which lead was the longest on an electrolytic capacitor, and placed it in the pad marked "+".  Unfortunately, the snap-in leads are short, thick, with a bend for "snapping" into the PCB, and most important of all - *of equal length*.  So, now we use that white stripe on the side of the capacitor that indicates the negative side, instead.  Here they are installed - you can check yourself where the stripes are oriented to confirm your own:



  C2 and C3 are the two caps pointed to with the arrows at top.  Same-same with installation, turn over the PCB, make sure the end with the OT's is properly supported (or at least supported in some way), apply pressure while soldering to keep the caps flush with the PCB.
   
*Step 20. -*
  Next up is the last cap - C4.  This one is in in the heater supply, so low voltage, but lots of uf's - 4700uf and 16V.  It's Step #20 because it's actually a bit taller than C2 and C3.  Follow the same procedure described above to install:



  Same photo, but C4 is the cap with the arrow at the bottom.


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## tomb

*Step 21. -*
  Now comes the Power Transformer (PT), the big Kahuna!  Pretty soon the PCB is going to feel and act like a giant barbell with lots of weight on the ends - ready to bend in the middle at a moment's notice.  So, remember to minimize the torque on the PCB as you install the PT.  Shown below is the PT next to the PCB:



  In a similar manner as the OT's, the PT is keyed with two pins on one end that are closer than the rest.  Take note of those pins as shown in the pic, and place the transformer into the PCB pads accordingly.  Also note that unlike the OT's, there are no plastic post spacers that will prevent the blue plastic rails from being flush to the PCB.  That said, the there's a lot of windings and pins there and it may be too much to ask Edcor to keep those blue plastic rails perfectly flush.  So, yes - you can get a large portion of the rails flush with the PCB, but probably not for their entire length.  That's OK - just do the best you can.
   
  As with the OT's, the PT is packed in close-cellular foam when it was shipped from the factory, so there may little bits of foam caught in spaces between the plastic rails and elsewhere.  This pic shows me using some canned air to blow out all of those foam bits:




   
  Here we see the PCB flipped over and ready for soldering the PT in place.  As with the OT's, I placed the PT on the PCB with the PT's pins in the proper pads, place the pine building board on top of the PT, and then flipped the entire arrangement so that it was upside down as shown in the pic:



  Be sure to support the OT's and the front of the PCB as shown.  It would be a shame to try to solder with the huge curve that weight on the end will inflict on the PCB.  That would probably end up popping some traces.  So, use some caution and make sure the PCB is supported on the ends.
   
  As with the OT's, the blue plastic rails will melt pretty easily if you leave the heat on too long.  So, solder hotly and quickly, but not so fast that you might get cold joints. 
	

	
	
		
		

		
		
	


	



   
  Finally, we see the PT installed and the PCB is now taking on a much more symmetrical look from front to back:



  All that's left are the RCA jacks and the IEC inlet!!


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## tomb

*Step 22. -*
  Install J2, the RCA jacks.  Part of Dsavitsk's excellently refined design is the use of some PCB-mounted RCA jacks.  I was suspicious at first, but these have worked out well on the prototypes and I sure am glad to not have to do any wiring!!
   
  Here's a shot of the RCA jack assembly - note the claw pins on both sides.  You simply punch these into the outside holes on the J2 area of the PCB and then solder the three pins - Left, Right, and Ground:



   
  A shot of the RCA jacks with the claw pins snapped into place on the PCB (support the front of the PCB again!).



   
  After applying solder to the three signal pins, here's where we're at:



   
  Next - the IEC (tomorrow, I hope!) and we'll be done with the PCB!


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## JamesMcProgger

Great work, I want to see the finished product


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## dsavitsk

http://temp.ecpaudio.com/Torpedo.shtml

The real one has silk screening on it, but you can get the general idea there.


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## dw1narso

parafeed! 

14inch long?!! :rolleyes:

I hope I would still be able to afford the kit...


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## tomb

*Step 23. -*
  Next up is the IEC inlet!  Pictured below are the 3 parts that make up the IEC inlet.  Note that these must be ordered separately! (The custom case back plate is also shown.)



  1) the IEC inlet and housing, 2) the fuse drawer, and 3) fuse and spare.
   
  To assemble the fuse drawer into the IEC, place the spare fuse either in the filter drawer or the IEC (in the IEC is shown):



   
  Next, place the primary fuse should be inserted into the fuse drawer (it won't sit in the IEC without the support of the fuse drawer):



   
  Snap the filter drawer in place.  Shown below is the filter drawer snapped in place alongside the back plate:



   
  Next we'll "snap" the IEC into the back plate and screw it into place.  The reason we do this at this point - instead of simply soldering the IEC onto the PCB - is that there is some play, backwards and forwards, with the PCB and the case fit-up.  This was done because all of the parts are essentially locked into place once soldered onto the PCB.  Over a length of 14 inches, this can cause huge issues if the parts don't fit perfectly or are not soldered into place exactly in alignment.  For that reason (and also because the solder leads on the IEC are so big), there is some play in the IEC leads, its pads, and its PCB screw holes (there are two of those).  To account for this and lock the perfect alignment in place from front to back, we'll mount the IEC onto the back plate, first.  Once that's done and it's bolted into place, then we'll solder the IEC - back plate and all - to the PCB. 
   
  The custom Beezar/ECP Audio case design includes a rectangular opening with radiused corners for the IEC.  This opening is machined perfectly for the IEC design drawings.  Unfortunately, being a molded phenolic, there are variances in the rectangular area on the IEC.  Because the entire rectangle is exposed without any sort of cover, frame or other finishing attachment, we left no tolerance gap on the back plate.  As a result, some IEC's will probably fit snuggly without an issue.  Others may need a slight bit of filing to fit.
   
  If yours doesn't fit perfectly (mine didn't on this build, either), wedge the IEC into place on the back plate as best you can.  Hold the assembly up to a light and you'll easily be able to see where there's clearance and where's there is none.  Remove the IEC and using a small flat file, file enough off of the high spots until you get it to snap in place:



   
  After some slight filing (careful - it is very easy to file the plastic/phenolic!), we have a perfect fit:



   
  Now that it's snapped into place on the back plate, we'll screw it flush to the back plate using the familiar 4-40 screws, washers and nuts.  Here's the view from the back with the screws in place and the IEC firmly mounted to the back plate:



   
  On the inside, we finish off the cap screw assembly with a flat washer, a lock washer, and nut:


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## tomb

To install the IEC/back plate assembly to the PCB, we "roll" the IEC-back plate assembly onto the back of the PCB for preparation of soldering into place.  There are several screw holes that need to be screwed down, first.  Again, remember - once we solder it, there's no moving it again.  So, we get the alignment correct and mount the screws, first. Shown below is one of the two screw mounting holes for the PCB - there's one on each side of the IEC inlet that screws it to the PCB.  Also indicated is a single screw hole for the RCA jack assembly that screws the RCA jacks to the back plate.



   
  Here we see the back plate around the RCA jack assembly.  The RCA jacks actually have a concentric ring that's larger than the RCA jack barrels themselves.  The holes in the back plate account for this, so be sure that the holes are fit around those larger rings and not mis-aligned ... _before _you screw the screw into the jack assembly.  On the first couple of builds, I actually tapped this assembly for 4-40 threads.  However, it turns out that the white plastic is soft enough that you can screw in a regular 4-40 screw and it will self-tap on its own.  (You can see some of the plastic chips in the previous pic as a result of doing this.):



   
  Finally!!  Here we see the bottom of the PCB with the IEC pins (3 of them) ready to solder.  Also shown are the screws that mount the IEC to the PCB (same flat washer, lock washer, and nut as used on all the other screws):


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## tomb

*Step 24. -*
  The final step for the PCB is the wiring, of which there is _very_ little.  This consists of the ground wire for the Alps pot, and the safety ground for the PCB.
   
  The pot ground wire is straightforward.  Unfortunately, I should tell you that it would be much easier to do right after you install the pot to the PCB and *before* you install the OTs.  Nevertheless, there is just enough room - with the right screwdriver - to install the ground wire at this point in the build sequence.  Cut a wire slightly longer than the distance from the PCB to the top pot screw as shown.  After soldering the wire into the PCB and unscrewing the pot screw, loop the other stripped end of the wire around the pot screw shaft and screw the screw back into the pot:



   
*Step 25. -*
  Next, install the safety ground wire at the back of the PCB.  To do this, cut and strip both ends of a wire about 2 inches long.    You can probably get away with it being much shorter, but there's no issue with looping it under the PCB and it's a lot easier to have a wire that's too long rather than one that's too short.
	

	
	
		
		

		
			





  On one end of the wire, solder a lug for a 4-40 screw as shown.  You can use a crimp-style lug, but since this is for "safety," please solder it, too.  Once you have that done, solder the other end of the wire by placing it into the pad on the bottom of the PCB.  The large hole in the PCB will allow us room for a screwdriver from above:



   
  HEY!!  We've finished the PCB!!


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## tomb

Step 26. -
*Clean the PCB!*
   
  It's a little unusual to detail cleaning the PCB like this, but remember -* HIGH VOLTAGE*.  There's more force behind higher voltage and it will "jump" across connections more readily than the typical SS or hybrid amps that are built on a PCB.  So, IMHO, cleanliness is part of the safety.  You don't want any of that old flux and soldering dirt to create enough of a connection that might encourage the voltage to arc across a set of leads.  So, we're going to clean this PCB well and show you how to do it easily and cheaply.
   
  Below we see the PCB with my essential tools for cleaning:



  Next to the PCB we see a small butter bowl and a toothbrush.  Next to that is a bottle of the alcohol that I use for cleaning.  This is 91%, but is less than a dollar at Walmart (last time I checked).  A quart will last you a long time.  I've tried several chemicals that they make supposedly specifically for solder flux, but none of them clean as well as 91% isopropyl and most of the other chemicals emit vapors so bad you need to use them outdoors.  So, I stick with the alcohol.
   
  Anyway, I pour an inch or so into the butter bowl and use the toothbrush to apply the alcohol across the entire PCB.  Use the brush to scrub the places where the flux is really thick:



   
  The alcohol dissolves most of the flux right away.  However, something a lot of people don't mention is that the dissolved flux-alcohol mixture doesn't go anywhere unless you try to drip all of it off of one side of the PCB.  That's not a very good strategy, so I use paper towels to pat up the dissolved mixture:



   
  So we're done, right?  NO! Take a look at this:



  That white stuff you see is the dried-up flux that was deposited after the alcohol evaporated.  So that means a single dousing of the alcohol, toothbrush, and paper towel didn't get it all.
   
  In reality, it takes _several_ rinses.  It took me six times to get the PCB to an acceptable condition:



  That sounds like a lot, but honestly, it was probably 15 minutes or less.  The alcohol evaporates so quickly - especially when using the paper towel - that multiple rinses go very quickly.  In the pic above, you may be able to still spot some white stuff around the solder joints, but all-in-all, it's pretty clean and good enough for me.


----------



## JamesMcProgger

This is starting to look better and better. 
	

	
	
		
		

		
		
	


	



   
  any estimate on the price of the kits? I asume beezar will be selling these as well.


----------



## tomb

*Step 27. -*
  Final Assembly!
   
  Below we see the custom Beezar/ECP Audio case from Context Engineering.  The case comes in two equal halves.  This was a primary design selection for the Torpedo.  That's because the transformers and other part heights require that the case depth is enough that the tubes barely stick out of the top.  IOW, you can plug a pair of tubes into the amp while it's cased up, but getting them out is a different story.  With the Context case design, however, you can simply unscrew the top two screws of each end plate and simply lift off the top of the case.
   
  Right now, the custom cases are bare-unfinished aluminum.  That may change if the amp is a great success with you guys, but in the meantime, it means more cleaning.  Unfortunately, I am not happy with the finish condition in which Context supplied the machined cases.  The reason being is that there are metal chips and dust everywhere.  As with the PCB above, this is HIGH VOLTAGE and the last thing you want around HIGH VOLTAGE are a bunch of conductive metal chips and dust.  So please-please-please, for your own safety, clean these things thoroughly.  I took a small screwdriver with a paper towel folded around its tip and ran it the length of every slot - including the slots that are used to fit the top and bottom case halves.  In addition after that, I gave the insides a thorough wipe-down and finished by running paper towel/rag around the inside of every machined hole.



   
  The first thing we need to do after cleaning the case parts is to install the standoffs onto the PCB.  Note in the pic above that there are four 4-40 size (1/8") holes.  The one close to the corner in the back is for the safety ground.  The other three, along the centerline of the case, are for the standoffs.  Please do not omit these.  The PCB is quite long and as you have already noticed, there is considerable weight on the ends.  The tubes are more or less in the middle, so support toward the middle, especially for the tubes, is very important.
   
  That said, there's no great complication to the standoffs.  I mixed up what I had with enough washers to cover the gap.  My one trick is to install the lockwasher on the screw side (top surface of PCB).  This helps to ensure that the screwed connection on the inside of the case comes loose last.  The PCB also has a slight curvature (down) width-wise, so you want enough of a standoff to provide some force onto the bottom of the case.  Turned over right-side up, it should be very difficult to slide the PCB with standoffs into the case because of the standoffs scraping along the case bottom.  Upside down, the standoffs should be just barely clearing with some scraping.  In my case, it took several washers with the smallest standoffs I had on hand.  I'll make certain to specify the best combination in the website's BOM, though.



  Shown at top is also the safety ground hole.
   
  Once you get the standoffs installed on the PCB, slide the PCB assembly into the bottom of the case.  Note that we're in the 2nd slot from bottom (not counting the end plate mounting holes slots).  Slide the PCB in until the back plate (still attached to the PCB) is against the case body.  Don't screw the back plate in at this point, though.  You should screw in the safety ground, first.  That way, you can shift the PCB back and forth as needed until you get the safety ground installed.  I used a 3/8" 4-40 cap screw with a washer and lock washer on the inside.  It's threaded through the safety ground lug and through the hole in the bottom of the case.  On the outside bottom of the case, finish off the screw with a flat washer and nut.
   
  Once you have the safety ground securely attached to the bottom of the case, install the screws into the standoffs and the back plate.  Here we see the case bottom with all of the screws in place (and the two bottom screws of the back plate attached):



   
  Next the amp doesn't sit so well on those standoff screws and safety ground nut, so I installed the rubber feet.  Because the case is so long, I used six instead of four - it just felt right:



   
  Last, install the front plate by lining up the plate holes with the pot shaft and the headphone jack.  Be certain that the headphone jack tube fits into the end plate hole and be sure the pot locating pin is also positioned correctly.  Finger-tighten the the nuts to both.  Install the bottom two screws of the front plate and go back and tighten down the headphone jack nut and the pot nut.  Finally, install the tubes (don't forget those), place the case lid on top, being careful to seat the top properly into the case bottom's mating-up slots.  Install the top screws for both end plates.  Install the volume knob.  (You may want to trim the shaft - more on that later.)  Here we see the front plate finished and installed:



   
*And we're finished building the Torpedo!!*


----------



## tomb

Quote: 





jamesmcprogger said:


> This is starting to look better and better.
> 
> 
> 
> ...


 
  Can't tell you at this point about price, but the answer to other question is sort of assumed.


----------



## Lil' Knight

Ready to make an order whenever the kit is up on Beezar, Tom


----------



## tomb

Quote: 





lil' knight said:


> Ready to make an order whenever the kit is up on Beezar, Tom


 

 Appreciate that, but Dsavitsk and I are working on an issue that came up with the amp.  I'm sure we'll have a solution shortly.


----------



## Gabe Logan

Same here. Ready to get this one on day one.


----------



## DingoSmuggler

Quote: 





tomb said:


> ...Dsavitsk and I are working on an issue that came up with the amp.  I'm sure we'll have a solution shortly.


 
  Any good news on this one?


----------



## tomb

Quote: 





dingosmuggler said:


> Any good news on this one?


 

 Not yet - but we're still working on it.


----------



## dsavitsk

The issue is that some of the tube types are picking up more noise than we like. So, we are working on a shielding solution. It is taking a while as we are both really really busy these days, and we just have not had the time to think about it. We figure we'd rather make everyone mad by delaying things, than make everyone really mad by shipping you an amp that is too noisy. But, rest assured, we are sitting on thousands of dollars worth of cases, transformers, circuit boards, tubes, and various other parts, so we have every incentive to get this thing done. Sometimes it just takes longer than hoped.

In the meantime, here's a little primer I wrote a while back on the ins and outs of designing a simple parafeed headphone amp. http://www.ecpaudio.com/pdf/parafeed_basics.pdf


----------



## vvs_75

Any good news? Wish you good luck guys to crack the problem!!!


----------



## tomb

Quote: 





vvs_75 said:


> Any good news? Wish you good luck guys to crack the problem!!!


 

 We're playing tag-team right now (kind of appropriate, given his avatar).  I ran some tests and then shipped it over to Dsavitsk.


----------



## vvs_75

Is it just nicely brushed raw aluminum  or some kind of coating also on your Torpedo enclosure?
  Just trying figure out what to do with my build.  thanks


----------



## tomb

Quote: 





vvs_75 said:


> Is it *just nicely brushed raw aluminum  *or some kind of coating also on your Torpedo enclosure?
> Just trying figure out what to do with my build.  thanks


 

 Yes.


----------



## vvs_75

Quote: 





tomb said:


> We're playing tag-team right now (kind of appropriate, given his avatar).  I ran some tests and then shipped it over to Dsavitsk.


 


 Any good news on testing? I really can't wait to get this kit!


----------



## tomb

Quote: 





vvs_75 said:


> Any good news on testing? I really can't wait to get this kit!


 

 Like a lot of us from time-to-time, other things get in the way.  I don't think Dsavitsk has had much time to check out the noise issue, unfortunately.  The noise is a highly-variable phenomenon.  It's completely inaudible with some headphones and some tubes, but will manifest itself with others.  Either way, it's never anything that you hear with the music.  I still listen to mine (the older proto) as my primary amp.  I've never been one for soundstage comments, but this amp has it in spades.  IOW, even if I know there's a slight noise issue, I prefer the musicality and imaging of the Torpedo, anyway.  This is just my opinion, of course, but there's stuff there that you will never hear with a solid-state or hybrid amp.
   
  KSC-75's with 6J6 tubes seem the worst for the noise.  5964 tubes seem the least noisy, whereas with some headphones such as Sennheiser HD25-II's - even with the 6J6 tubes - the noise is completely inaudible.  That's very odd, because one would think that with completely closed in phones like the HD25's, you'd be able to hear every flaw.  With the lid off, Dsavitsk reports that he can't hear any noise.  With the lid on, he can, which is another really odd thing, because the case is completely aluminum and shouldn't have any effect unless it's RF noise.  So,the problem is definitely that the tubes are picking up the noise through the air.  In my testing, the addition of the choke helped and we will recommend that now instead of the resistor - but it may have had more to do with providing more shielding to the tubes than anything in the circuit.  It's all in the tubes.  I guess you get what you pay for when using $2 tubes.  I think the 5964's are $4 ea, so they're a bit better, IMHO.
	

	
	
		
		

		
		
	


	






   
  Some of you who have built a Starving Student and remember the structure of the 19J6 tubes may be able to remember that the grid in this tube family is somewhat exposed outside of the plates.  The grid is actually stretched between copper posts that are on the outside of the plates, so the grid wiring connecting to those posts is exposed.  There have been issues, too, of the Starving Student picking up noise through the tubes, whether cell phone, computer, etc.  The 5964 tubes seem a bit more conventional in construction and have plates that completely enclose the grid structure.  This may explain what's going on.
   
  In any event, we may decide to go ahead with the kits anyway - with full disclosure of the noise issue.  As I said, it's my preferred amp regardless - and I'm using 6J6W tubes right now and the resistor instead of the choke.  Hopefully, Dsavitsk will have something to add soon.


----------



## digger945

I have the later prototype, with choke. It is my main amp now.
  As you said, it has some hum with certain tubes or headphones, and others it is not noticeable. Regardless, it does not interfere with my listening, even at low levels. 
  Listening to the new PS500 now, and this amp really shines. Very enjoyable.


----------



## vvs_75

To find a better tubes that do not hum at this price should be not a problem. Any infor on the kit price?


----------



## HiGHFLYiN9

Did you guys try experimenting with some grounded tube shields? I wonder if that would help at all.


----------



## tomb

Quote: 





highflyin9 said:


> Did you guys try experimenting with some grounded tube shields? I wonder if that would help at all.


 

 It's a good thought - and one that Dsavitsk had almost immediately.  I tried some great shields that were not grounded without much success.  Unfortunately, I was not very good at grounding them.  I couldn't get the solder to stick and was quite afraid to have bare wire leads bouncing in and around all that high voltage.
	

	
	
		
		

		
		
	


	




  I'm hoping Dsavitsk will have a bit better luck at it and maybe have different results.


----------



## dsavitsk

OK, here's where things stand -- As has been noted, the hum is very low. Using the amp with Grados, the hum is nearly drowned out by the fan noise from my laptop. It is very non-intrusive. I won't put a number on it as I don't have anything well enough calibrated to tell. Some prototypers didn't notice it until we told them it was there. However, it is there, and if you are someone who needs absolute silence, this is not the amp for you. 

I have tried a number of different shielding techniques, and none of them seem to do much of anything. Additionally, there are not "expensive" tubes that will solve the problem. So, unfortunately, at least for now, it is what it is.

That said, we still think it is a good way for someone to be introduced to tubes and transformers. It is a fun amp that sounds good and does not cost too much, and we think most people will be pleased with it. So, I think the plan is to put the first batch up for sale, but at a discounted rate in light of the noise. We'll continue to work on finding a solution for when/if we do a second batch, and perhaps the collective wisdom of a few dozen builders will find something we missed.

Depending on Tomb's schedule, we should post the details sooner than later.


----------



## Magedark

Sounds like exciting stuff here.


----------



## FrankCooter

Having incorporated a number of Doug's designs into my own builds over the years, I have nothing but the highest respect for his work and very extensive contributions to the DIY audio scene. He is one of main reasons I read this forum. If he says the noise/hum is non-intrusive, I really doubt an average user would know it's there at all. Doug is a perfectionist.
   
  Although simple in concept, it can be extraordinarily difficult to build a totally quiet tube based headphone amp incorporating both power transformers and output transformers on the same chassis. If you listen closely with sensitive headphones like Grados, even the most expensive commercial amps of this type are not totally quiet. Doug of course, is trying to bring this level of performance to a previously unattainable price point. This is a very worthwhile goal.
   
  If your hum/noise is indeed caused by transformer interaction, your options, short of redesigning the amp for an external power supply, are at least in my experience pretty limited.
  You've already got the maximum possible physical distance between the power and the output transformers. You've already got the transformer cores at 90 degrees from each other.
  Next step would be to order transformers with appropriate shielding. If I had to choose, I would start by shielding the output transformers first. Ideally, the power transformer AND the choke should also be shielded (the choke may be causing more problems than it solves).  Sometimes rotating the power transformer to something other than a 90 degree core orientation can help, as can putting the transformers on a different mounting plane. Ultimately, you might want to think about replacing the EI core power transformer with a toroid or "R" core type.
   
  Another possible approach would be to change your tube type to something that is less sensitive to externally induced hum. Everybody loves the high mu/high gm types in this sort of application, but they're almost all rf types and love to act like little antennas. If you can spare the gain, a paralleled 12AU7 should work with your output transformer. An EL84 type in this position would be something different and might be very interesting.
   
  You've probably  been through all the above and more already. I'll bet you're being too picky! Best of luck in this very worthwhile project!


----------



## JamesMcProgger

Quote: 





dsavitsk said:


> OK, here's where things stand -- As has been noted, the hum is very low. Using the amp with Grados, the hum is nearly drowned out by the fan noise from my laptop. It is very non-intrusive. I won't put a number on it as I don't have anything well enough calibrated to tell. Some prototypers didn't notice it until we told them it was there. However, it is there, and if you are someone who needs absolute silence, this is not the amp for you.
> I have tried a number of different shielding techniques, and none of them seem to do much of anything. Additionally, there are not "expensive" tubes that will solve the problem. So, unfortunately, at least for now, it is what it is.
> That said, we still think it is a good way for someone to be introduced to tubes and transformers. It is a fun amp that sounds good and does not cost too much, and we think most people will be pleased with it. So, I think the plan is to put the first batch up for sale, but at a discounted rate in light of the noise. We'll continue to work on finding a solution for when/if we do a second batch, and perhaps the collective wisdom of a few dozen builders will find something we missed.
> Depending on Tomb's schedule, we should post the details sooner than later.


 

 I like the idea. just waiting for the price now, this might be something to keep me busy on the xmas break.
   
  what other headphones did you guys tried it with? AKG K series by any chance?


----------



## tomb

Quote: 





jamesmcprogger said:


> I like the idea. just waiting for the price now, this might be something to keep me busy on the xmas break.
> 
> what other headphones did you guys tried it with? AKG K series by any chance?


 

 The amp does very well with many headphones, but admittedly it makes Grados sing and is optimized for those.  It does great with KSC-75's, Senn HD-25's, and Sony V6's, all at the higher impedance setting.  While I don't have a pair (yet!), I can attest to the fact that the Denon 2000's come very close to Grados in having an affinity for the Torpedo.  They sound marvelous through the Torpedo!  I haven't listened extensively with Senn Hd 580/600's, but I will try to do that in the coming days and report back.
   
  I have the K701's and I'm not sure those are as good a match.  If you're familiar with those phones, you must know they are very persnickity about amp choices and in my experience, tend to favor something that can put out huge current impulses on demand (high Class A bias SS or hybrids).


----------



## JamesMcProgger

I dont have the K701 but I do have the K601 and I know how picky is regarding amplification, actually using the Gilmore Lite and I like them a lot. But as long as it doesnt do terrible things to the sound, which is unlikely, I could try/welcome a new coloration.
   
  and if not, I always have the grados, also the Fischer FA003 which is very similar to grados regarding amplification, they need little power to shine and respond well to warm colorations.


----------



## tomb

Quote: 





jamesmcprogger said:


> I dont have the K701 but I do have the K601 and I know how picky is regarding amplification, actually using the Gilmore Lite and I like them a lot. But as long as it doesnt do terrible things to the sound, which is unlikely, I could try/welcome a new coloration.
> 
> and if not, I always have the grados, also the Fischer FA003 which is very similar to grados regarding amplification, they need little power to shine and respond well to warm colorations.


 
  Well, I always feel guilty when I suggest that maybe a pair of headphones may not be optimum for a certain amp.  However, in my experience the K701 is right up there with the most persnickity loads for any amp - probably only exceeded by the K1000.  Wonder why AKG does that?  Their other phones are not amplifier-deviants and perform quite well under a number of scenarios - probably your K601 will do alright, too.


----------



## vvs_75

Any news on price and availability? thanks


----------



## tomb

Quote: 





vvs_75 said:


> Any news on price and availability? thanks


 

 I should have it on sale by the end of the week.  Price for the short kit will be $180 for the PCB, three transformers, and the custom case.  I'm working on the BOM and should have a price soon - it will be fairly trivial.  Everything is in the PCB, transformers, and case.


----------



## vvs_75

Quote: 





tomb said:


> I should have it on sale by the end of the week.  Price for the short kit will be $180 for the PCB, three transformers, and the custom case.  I'm working on the BOM and should have a price soon - it will be fairly trivial.  Everything is in the PCB, transformers, and case.


----------



## tomb

Quote: 





vvs_75 said:


>


 

 Yeah, I know - every time I make a prediction, it goes south.  My wife decided to put up the Christmas tree and decorations this weekend.
	

	
	
		
		

		
		
	


	




  So that put a damper on my time.
   
  Rest assured, the Torpedo is number 1 on my priority list and Dsavitsk and I are in constant communication about it.


----------



## liamstrain

Quote: 





tomb said:


> Yeah, I know - every time I make a prediction, it goes south.  My wife decided to put up the Christmas tree and decorations this weekend.
> 
> 
> 
> ...


 


  Mine too. I feel yah. Looking forward to this when you do have time to get to it.


----------



## dsavitsk

Tom and I have been emailing BOM revisions back and forth. It really is almost ready. Just a matter of getting a website up at this point, and I think Tom is almost done with it..


----------



## Magedark

I wonder if I'll be able to save up to make such a fine looking kit .


----------



## tomb

The short kits and other things are available for pre-order now on Beezar.  There are 29 available.
   
  I will not be shipping until Monday, 12/19/2011.  Hopefully, that will give me time to finish the website.  I'll have a link to a complete BOM by tomorrow night.


----------



## digger945

Very nice looking kit guys. 
   
  You wouldn't happen to have any extra end panels would you Tom?


----------



## tomb

Quote: 





digger945 said:


> Very nice looking kit guys.
> 
> You wouldn't happen to have any extra end panels would you Tom?


 

 Unfortunately, I don't think so.  I'll try to have extras made in the future, though.


----------



## DingoSmuggler

Quote: 





tomb said:


> The short kits and other things are available for pre-order now on Beezar.  There are 29 available.
> 
> I will not be shipping until Monday, 12/19/2011.  Hopefully, that will give me time to finish the website.  I'll have a link to a complete BOM by tomorrow night.


 






great news, I'll be placing an order this week for sure. Just need to be deciding what tubes i wish to get with it.
   
  In general does this amp's sound vary a lot with the different tube options you've tried? (not referring to the mysterious _noise issue_)


----------



## dsavitsk

I'm sure Tom will have something more specific to say on the subject, but I don't think it makes a huge difference.


----------



## Gabe Logan

Placed my order so hopefully i am one of the lucky few. Been looking forward to this amp build for quite some time but bad news is i misplaced my soldering station and can't seem to find it.


----------



## DingoSmuggler

OK, order placed.
   
  I just decided to get a pair of each tube available at beezar. A bit of rolling cant go astray.
	

	
	
		
		

		
			




  This should be a nice new years project.


----------



## tomb

Quote: 





dingosmuggler said:


> great news, I'll be placing an order this week for sure. Just need to be deciding what tubes i wish to get with it.
> 
> In general does this amp's sound vary a lot with the different tube options you've tried? (not referring to the mysterious _noise issue_)


 

 I think it's subtle, instead of wide variances.  The best I recall when I was rolling a lot was that the 6J6 seems to have the best impact, but the 5964 may be smoother with better highs.  The 5844 sounds different than either of the other two and seemed to have an exagerated mid-range.
   
  To be honest, though, I'm hoping you guys can give us a better idea of the differences and what you like.  Those are just the three types that I carry, though.  When you enter 6J6 into TDSL, you get this:
1216, 5844, 5964, 6030, 6045, 6099, 6101, 6535, 6927, 6CC31, 6J6A, 6MNN3*, CK6101, CV5046, CV8160, CV8231, ECC91, M8081, T2M05
  Some of those can't be found, I think, but it still leaves a heckuva lot to pick from.


----------



## DingoSmuggler

When I've had a look around for_ torpedo tubes _





, there did seem to be some different ones here and there, but very few sources offering matched tubes. But I won't really get overly fussed about looking at what's around till I've had a play with the 3 beezar options.


----------



## dsavitsk

There is a little bit of history about this tube at http://www.r-type.org/exhib/aaa0399.htm


----------



## tomb

Quote: 





dsavitsk said:


> There is a little bit of history about this tube at http://www.r-type.org/exhib/aaa0399.htm


 

 Very cool!


----------



## tomb

I've posted the BOM separately right now until I get the website built.  As usual, I have it available in three formats - just in case:
TorpedoBOM.htm
TorpedoBOM.pdf
TorpedoBOM.xlsx
   
  Dsvatisk wanted me to list cap dimensions, but for the time being, let's just say if you want to substitute - be certain that the substitute cap does not exceed the dimensions of the caps listed on the BOM (can be looked up on Mouser/DigiKey).  A tad overy 48mm is the height limit in the case from the top of the PCB.  Of course, just about anything will fit in C11 and C12 - the numerous alternates listed in the BOM will all fit, with the Clarity Caps probably the largest.  If in doubt, you can ask me to measure it until I get drawings/dimensions posted.


----------



## digger945

Transistors Q1, Q2, Q3, Q4 .... 2N5087 ... qty should read 4.


----------



## tomb

Quote: 





digger945 said:


> Transistors Q1, Q2, Q3, Q4 .... 2N5087 ... qty should read 4.


 

 True, but it was supposed to be a little pack (all 4) that I would sell from Beezar at 50 cents.  Unfortunately, I slipped up and didn't include that in the original listing (now changed).  I changed the description in the BOM to "matched pack of 4", but it will be a little bit tonight before I get the change uploaded because of below -
   
  Dsavitsk tells me the 1N4007 might be too noisy.  So, I'm changing it back to the 1N5062, but they aren't available at DigiKey.  I'm waiting on him to tell me which one is best out of what they have.  When he does, I'll upload the BOM with the changes.  Sorry about that.


----------



## tomb

OK - the BOM has been updated and uploaded.
   
  Changes:

 HV rectifier back to 1N5062.  The DigiKey option is the best they have available, but we still recommend the 1N5062 (Mouser).  I will start carrying them as a selection at Beezar.
 The comment on LED's was trimmed back.  (I didn't keep up with the design changes.)  What's important is to keep the LED *RED *and at a forward voltage of about 1.8V.
 The small signal transistors (TO-92, 2N5087's - 4 needed) were edited in description to include "pack of 4" and a footnote added stating the HFE matching is not really critical, but Beezar supplies them this way, anyway (link also added).


----------



## jdkJake

TomB,
   
  The link for J1 needs to be fixed in the BOM. It is currently pointing to  a Wima Capacitor.


----------



## jdkJake

TomB,
   
  Another BOM question. R4 and R5 are spec'ed at 68R, 1/2 watt. The link goes to a 1/4 watt part. Acceptable? 
   
  Or go with something like: 71-RL20S-G-68?


----------



## tomb

Quote: 





jdkjake said:


> TomB,
> 
> Another BOM question. R4 and R5 are spec'ed at 68R, 1/2 watt. The link goes to a 1/4 watt part. Acceptable?
> 
> Or go with something like: 71-RL20S-G-68?


 

 Thanks for that catch on the Neutrik headphone jack.  Corrections have been made and all BOM formats have been re-uploaded.
   
  As for R4 and R5, that's the old V-D military spec vs. commercial rating difference.  Those are RN60 resistors, which in everybody's book are 1/2W.  However, the RN60 is a military spec designation, so the wattage listed is de-rated by half.


----------



## dsavitsk

The 68R resistors set the CCS current.* Each should carry about 16mA and drop slightly over a volt. That means that they dissipate ~0.017W. 1/4W parts are fine so long as they are OK at high voltage and fit the board.

*The transistor's Vbe is ~0.7V. The biasing LED drops ~1.8V. The resistor will drop enough volts to make up the difference between these -- so, (1.8 - 0.7) = 1.1V, and by V=IR, 1.1 = I*68 or 1.1/68 = I = ~16mA. We really don't recommend pushing the current much higher than this, though a little lower is OK, and a little experimenting is also OK. For 18mA, you would use 62R resistors, and for 13mA you would use 85R. Anything in there is OK, but we felt that 16mA was a bit of a sweet spot.


----------



## n_maher

Great work as usual guys.  I still enjoy the heck out of my prototype.


----------



## jdkJake

Thanks TomB, thanks dsavitsk.
   
  Mouser order is on the way. I picked up the choke as well as the resistors for R2, so, I might experiment a bit. I am in the middle of another big project right now, but, I am making time for this one. I am really curious to hear a true, transformer-coupled build.
   
  I am also set on tubes. John Kendall was selling two-for-one 6J6A (still is), which, at a cost of a buck a piece (recently bumped to $1.25 a piece), makes voicing this amp a solid bargain. I now have a lifetime supply. 
	

	
	
		
		

		
			




   
  I have three 6J6A "orphans", so, if anyone needs to match a construction, let me know. I also  splurged a bit and bought some de-luxe 5964's as well (just under $5 a piece). I seem to be particularly partial to Sylvania tubes and could not resist. In any case, I am set.
   
  Looking forward to the build!


----------



## tomb

Quote: 





n_maher said:


> Great work as usual guys.  I still enjoy the heck out of my prototype.


 

 We must be doing good to deserve your attention over here these days.
	

	
	
		
		

		
		
	


	










  Seriously, thanks for the good words.


----------



## tomb

Running a little behind as usual.  My daughter's hot water heater went out this weekend.  I was only able to get the plumbers into her house today.
   
  I hope to get some of the short kits shipped tomorrow.  Thanks for your patience.


----------



## n_maher

Quote: 





tomb said:


> We must be doing good to deserve your attention over here these days.
> 
> 
> 
> ...


 


  What, a Mod can't lurk? 
   
  And yes, you're doing great work.


----------



## tomb

Well, as usual - I was behind in getting these kits out.  However as of today, every order has been shipped. 
	

	
	
		
		

		
		
	


	



   
  EDIT: Now, back to work on the website.


----------



## Gabe Logan

Good news!. Excited to hear how it sounds and even bought a new solder station to replace the one that magically disappeared on me.


----------



## tomb

Just a note about the LED's used to set bias and current - I noticed that one of you bought several LED's from me on one order. Not trying to single anyone out and they will remain namelesss, but ... this is just to be certain that purchase wasn't for the Torpedo.  You need to stick with the RED LED's that are recommended on the BOM.  To explain, I don't think Dsavitsk would mind my quoting a section out of one our e-mails:
   
  Quote:


> ... [size=11pt]the plate current is set by ((Vf - Vbe) / R4) With a red LED, you get (1.8 - 0.7) / 68 = 16mA. If this were a blue LED with a 3.3V drop, it would be 38mA which would a) not work and b) likely cause the power transformer to burn up[/size].


 
  So in the Torpedo, the voltage drop of the LED is all important and is usually dictated by the color of the LED.  I assumed that the particular customer was purchasing them for something else, but as I said, just in case ...
   
  There's more background, but I'll let Dsavitsk elaborate if he wishes.


----------



## DingoSmuggler

I bought some white LEDs with my torpedo kit, but they weren't for torpedo usage


----------



## tomb

Quote: 





dingosmuggler said:


> I bought some white LEDs with my torpedo kit, but they weren't for torpedo usage


 

 Oops - I wasn't trying to identify who you actually were!  I just wanted to make certain for everyone, since as Dsavitsk said, _different LEDs could be potentially damaging to the amp_. That's not to say other LEDs can't be used, but we should get a check and approval on them before substituting them.


----------



## DingoSmuggler

tomb said:


> Oops - I wasn't trying to identify who you actually were!  I just wanted to make certain for everyone, since as Dsavitsk said, _different LEDs could be potentially damaging to the amp_. That's not to say other LEDs can't be used, but we should get a check and approval on them before substituting them.



yep, I realise that. I was just easing your concerns by assuring you that I was using the correct LEDs


----------



## dsavitsk

As I said to Tom, we designed this around red LEDs with a 1.8V forward voltage drop. On the CCS, and I hesitate to say this, you could potentially use different colors but you will have to adjust the current setting resistors. For instance, if you used an led with a 3.3V drop, then for a 16mA CCS you would need (3.3 - 0.7) / 0.016 ~ 162R resistor. However, red led's, in general, have a much lower impedance than blue or white which makes them a better choice for CCS performance, and you can't see these parts anyway, so there is no advantage to fancy colors.

Similarly, for biasing the tubes, red led's set the bias at (1.8V + 0.7V) = 2.5V, which seems to be a good operating point. Much lower than that, such as with an IR led, and the tube is more likely to draw grid current leading to higher distortion. Higher and it will push the plate voltage too high which may lead to clipping. Plus, the AC performance of red led's is, as above, advantageous on this position.

This is a DIY circuit, and we encourage experimentation. But, please be sure that you know what you are doing, understand the risks (to yourself and the hardware) and make smart choices. Other led's are not, in our judgment, going to improve performance.


----------



## jdkJake

Unexplained ordinance arrived today. That was an interesting conversation.
   
  "Hon, a package came for you today. Did you really order a torpedo?!?"
  "Um, perhaps I should explain, it's not what you think...."
   
  Anyway, the short kit arrived today expertly and thoughtfully packaged. TomB and Beezar continue to have the best shipping and handling bar none.
   
  TomB/dsavitsk, any chance of getting the schematic posted or PM'ed? The build is much more enjoyable when I can follow along from the hymnal.


----------



## tomb

Quote: 





jdkjake said:


> Unexplained ordinance arrived today. That was an interesting conversation.
> 
> "Hon, a package came for you today. Did you really order a torpedo?!?"
> "Um, perhaps I should explain, it's not what you think...."
> ...


 
  Thanks for the kind commenst.  As for the schematic, I am working on the web site during every spare moment.
   
  A question, though, how the heck did you get a Guvment Employee Postal Worker to deliver a package to you today?


----------



## dsavitsk

There is an "unofficial" schematic at http://www.ecpaudio.com/Torpedo.shtml with parts labeled. I'll get a power supply up later, and Tom should have the website up soon.

-d


----------



## dsavitsk

tomb said:


> A question, though, how the heck did you get a Guvment Employee Postal Worker to deliver a package to you today?:blink:




I had a USPS package delivered on Christmas morning last year. I tried to invite the deliverer in for some breakfast, but she had other packages.


----------



## jdkJake

Quote: 





tomb said:


> A question, though, how the heck did you get a Guvment Employee Postal Worker to deliver a package to you today?


 


  Surprised me as well. I heard the mail truck pull up and there it was, on the front porch. No other mail though. 
   
  Made my day.


----------



## jdkJake

Quote: 





dsavitsk said:


> There is an "unofficial" schematic at http://www.ecpaudio.com/Torpedo.shtml with parts labeled. I'll get a power supply up later, and Tom should have the website up soon.
> -d


 


  Great. Thanks.


----------



## HiGHFLYiN9

Got my order in over the holidays. Thanks again gents for all the hard work you put into this.


----------



## jdkJake

Rainy day in Florida as the cold front comes in. Good day to build an amp.
   
  TomB/dsavitsk,
   
  I assume this jumper also needs to be installed to connect the tube heater filaments to the power supply?
   
   

   
  Just checking to be sure as the build pics and text on page 1 does not mention it.


----------



## dsavitsk

Nope, no jumper.

Temporary power supply schematic up at http://www.ecpaudio.com/Torpedo.shtml


----------



## jdkJake

Quote: 





dsavitsk said:


> Nope, no jumper.
> Temporary power supply schematic up at http://www.ecpaudio.com/Torpedo.shtml


 


  Ah, just a couple of vias to the top to jump a couple of bottom traces. Got it.
   
  Thanks again for the temp schematics.


----------



## Gabe Logan

Mine just came in. The care in packaging everything was great. Thanks tomb and dsavitsk.


----------



## jdkJake

_*"Burnin' and Lootin' tonight!..."*_
   
  Another Torpedo lives and we be jammin'.
   

   
  The build itself went fine. Extremely straightforward. The schematics were nice to help understand the parts and their roll in the circuit, but, you could easily build this from the BOM and the photo strip TomB posted on page 1 and 2. The main issue, as TomB has pointed out is the awkwardness of the board once you get the transformers installed. Talk about a moment arm! Nothing insurmountable mind you, just something to be aware of. 
   
  I went with the choke and a pair of Mundorf MCap MKP's I tagged onto a Parts Connexion order during one of their 20% sales (~$4.76USD a piece).
   

   
  So, far, while still very, very early, I am liking what I am hearing. Even out of the iPod line out using 192k AAC rips, the 225's sound mighty tasty. I have been running it for a couple of hours now. B+ started at ~229VDC and is down to about ~224 at this point. The tubes were NOT matched, so, the plate loads vary considerably at this point (PL is ~133VDC and PR is ~157VDC). I suspect one could get this much closer with a little effort. Perhaps later in the week once everything is boxed up and a bit more stable.
   
  The case is still in paint, but, should be ready sometime tomorrow. I will feel a bit better moving it around it once it is boxed up. I am dying to hear what is sounds like on the main rig with the HF-2's.
   
  Much thanks to dsavitsk and TomB for putting in the hard hours and making this build possible. It is quite the accomplishment.
   
  A toast to the Torpedo, dsavitsk and TomB with the appropriate (and equally tasty) libation.


----------



## ujamerstand

How do you like it to your EHHA rev.A?


----------



## jdkJake

Quote: 





ujamerstand said:


> How do you like it to your EHHA rev.A?


 

 Too early to tell.


----------



## ujamerstand

Please do let us us know!


----------



## tomb

Quote: 





jdkjake said:


> _*"Burnin' and Lootin' tonight!..."*_
> 
> Another Torpedo lives and we be jammin'.
> 
> ...


 

 Yes - one of my favorite libations, too.  Purely a coincidence, of course.


----------



## jdkJake

TomB,
   
  Another quick BOM correction. Part D9 (1N4448) is specified as quantity two, should be quantity 1.
   
  There, I just shaved $0.13USD off the BOM. Whoo Hoo!!


----------



## jdkJake

I realize the PL/PR measurements don't necessarily reflect tube mu/gm matching characteristics, so, I decide to take a quick, crude measure to see how close this set of tubes I was using matched in output. At the end of the evening, the PL and PR measurements between the set of tubes I was using had a difference of ~30VDC (~130/160VDC respectively). This actually turned out to reflect about ~2db in channel imbalance for this particular set of tubes (zero attenuation on the Alps/high impedance setting). While not offensively off, it was slightly noticeable.  
   
  I went through a couple of the other tubes I have of the same construction and now have a set that measures ~158/~162VDC respectively. This turns out to be less than ~1db of channel imbalance (zero attenuation on the Alps/high impedance setting). I think this is pretty darn good for tubes especially taking into account the channel tracking/imbalance error margin inherent in the RK27 itself. I am going to leave this set in for a while and listen with it for a while.
   
  BTW, my case is still in paint. Needed another coat in a couple areas (mainly on the clam shell connection). So, casework is put off yet another day.


----------



## vvs_75

Got a question about Q5,Q6 and VR1.
   
  From post #9:
  "Torque is probably too strong a word, though, because you want to tighten them so that the lock washer is obviously compressed, but not enough so that the thermal pads get cut.  There is *high-voltage going through the CCS transistors, so you don't want them shorting to the heat sink*."
   
   
  The MJE350 and NJM2396F63 looks like they isolated,  in which case thermal pad  or paste  requires only for better heat transfer not isolation from heat sink.  Just want to be sure. Thanks


----------



## tomb

Quote: 





vvs_75 said:


> Got a question about Q5,Q6 and VR1.
> 
> From post #9:
> "Torque is probably too strong a word, though, because you want to tighten them so that the lock washer is obviously compressed, but not enough so that the thermal pads get cut.  There is *high-voltage going through the CCS transistors, so you don't want them shorting to the heat sink*."
> ...


 
  Back then, there was the possibility that other transistors could be used.  In fact, the LM317 was used during the first prototyping.  Also, there are many versions of the MJE's that have metal backs.  However, since Dsavitsk standardized on only _isolated_ (all plastic) transistors and VR, you are correct.


----------



## vvs_75

Tom,
  Thank you for the prompt respnd. Also thank you for the top-notch packaging, you guys rule!


----------



## jdkJake

All cased up and looking fine. The case itself is really nice, just needs a coat or two of paint to bring it some personality. 
	

	
	
		
		

		
		
	


	



   

   

   
   
  I tapped out 6-32 thumb screws for the end panels, which worked great. A very easy case to tap due to it's construction.
   
  The only issue with the build right now is the case itself. While it looks great and is a very nice addition to the build, with the top piece in place, I get the slight hum mentioned earlier in the thread. The hum is way low in the background, but, there nonetheless. Without the top piece in place, the amp is silent. Very silent. I am using 6J6A tubes and Grado SR225/HF-2 which expose the hum. I have not yet tried other tubes/headphones.
   
  So, the good news is that the hum seems to be directly attributable to the case, at least in my build. Worse comes to worse, that can be addressed a variety of ways. I do have a couple of shielding ideas I am going to try that I will report back on.
   
  In any case, this is certainly not a show stopper. It is VERY low and once the music starts, most material will make imperceptible, especially at volume. Just a bit of a shame as the case is really, really nice and the sound of this amp is oh so very sweet. I spent a good amount of time with it yesterday and brought the HF-2's to the party.  A most fine combination to say the very least.
   
  Anyway, time to get creative and figure this one out.


----------



## tomb

Great pics!
   
  Someone has suggested grounding the heat sinks.  That should only take a few short leads - maybe even jumpers.  If you can get to it before I do, please let us know.


----------



## jdkJake

Thanks TomB. Photos are easy when the source material is so photogenic. 
	

	
	
		
		

		
		
	


	



   
  So, not sure what you mean by grounding the heat sinks. I went brute force and put a big hunk of copper between the tubes and the power supply.
   

   

   
  Did not make a lick of difference. I moved it forward as well as back in a few different places within the amp. No change. The top lid still telegraphs the hum, which is somewhat puzzling considering the wave length at that frequency. 
   
  The problem, at least from my perspective, is that big ass E-core at the back of the chassis. Once we isolate that bad boy (save for sawing the board in half), we will be cooking.
   
  Serious contemplation begins now....


----------



## tomb

Whoa! I'm amazed that you tried that! Many thanks for such an effort.
   
  Actually, I was thinking of perhaps running a wire lead from one of the heat sink pins underneath the PCB to a pad that was connected to the ground plane (for each heat sink). Whether the heat sinks are grounded or not depends on whether the heat sink PCB pads are connected to the ground plane.


----------



## DingoSmuggler

Looking good jdkJake. 
	

	
	
		
		

		
		
	


	



   
  I was considering doing something similar with the chassis, but wasn't quite sure what colour I would prefer, but that satin black looks like a winner for sure.
  I'm still considering trying a textured coat though on top, anyway I'll update on here whatever i end up doing.


----------



## jdkJake

Well, looks like I pulled a boneheaded maneuver that did not materialize until today.
   
  I was listening to the amp (with my LCD2's actually) and shut it off to move it to another room to try out another shield I made. When I re-applied power, there was nothing, nada, zip. No AC at all.
   
  Thinking that was very odd, I pulled the fuse holder to check the fuse (which was fine) and two lovely bits of metal fell out, Well, one fell out, the other had to be extracted. Looks like I was more than a bit heavy handed when I installed the fuse drawer. I must have jammed it in with enough stress that it broke the fingers that make contact between the drawer and IEC socket to pass power through the fuse. They are now too short to make contact at all. Lovely.
   

   

   
  Looks like I was lucky it worked as long as it did. Oh well, I put another fuse drawer on order. I will see if I can rig up a temporary fuse holder until the replacement arrives. 
   
  Let this serve as a caution. The fuse drawer is apparently somewhat fragile. That or I am far more powerful than I ever knew. 
	

	
	
		
		

		
		
	


	



   
  So, be gentle on installation of that fuse!


----------



## tomb

The Torpedo website is up and running!
   
   
  P.S. Sorry to hear about that fuse drawer.


----------



## Gabe Logan

Got mine finished up yesterday and have been rolling between the 5694,5884 and 6J6. I now hear the imaging that you were talking about long ago tomb and is something i have been lacking in my other amps that i've previously owned.
   
  Now that i've seen jdkJake's case i'm tempted to take it apart and do a paint job with wet sanding and buffing to get a mirror finish but i'm having a hard time turning it off.
   
  By the way tomb on the Overview page the link to a DMM sends me to a Drip Irrigation Kit instead.


----------



## tomb

Quote: 





gabe logan said:


> Got mine finished up yesterday and have been rolling between the 5694,5884 and 6J6. I now hear the imaging that you were talking about long ago tomb and is something i have been lacking in my other amps that i've previously owned.
> 
> Now that i've seen jdkJake's case i'm tempted to take it apart and do a paint job with wet sanding and buffing to get a mirror finish but i'm having a hard time turning it off.
> 
> By the way tomb on the Overview page the link to a DMM sends me to a Drip Irrigation Kit instead.


 

 What, you don't want to grow roses in that case?  I'm surprised.  Guess I'll have to fix that link.
	

	
	
		
		

		
		
	


	



  
   
  EDIT: Should work now ...


----------



## Gabe Logan

Ha, as tempting as that sounds i'll stick with a DMM instead.


----------



## funch

Hey Jake, you gotta lay off the steroids. 
	

	
	
		
		

		
		
	


	




 How did the amp sound with the LCD2's?
   
  Again, nice case work.


----------



## crappyjones123

The box from tom is finally in my possession as of 15 minutes ago. Holy mother of all things well packaged...Tom, I hope you don't take this the wrong way but you are insane brother man. i used to think I was a fairly cautious packer but you put me to shame and swept the floor with me. 

 Still waiting on the parts from Mouser but put whatever I have so far together to see how it all fit and am quite pleased so far. 

 I haven't had any financial dealings with Tom in the past but I can definitely see where he gets his good name from, and deservedly so. 

 Hopefully the mouser stuff will arrive tomorrow otherwise I have to wait till Tuesday to stuff this puppy. Any tips before I do anything in terms of grounding or noise/hum reduction?


----------



## glenda

Quote: 





tomb said:


> Great pics!
> 
> Someone has suggested grounding the heat sinks.  That should only take a few short leads - maybe even jumpers.  If you can get to it before I do, please let us know.


 


 I have an spud amp that is similiar to this one.  It can be worthwhile to ground the heatsinks for the heaters,  they tend to pick up the EMI from the transformers ( I saw 60hz @ -90 reduced to -100db) and this was a separate chassis.  Another thing to try would be adding  decoupling capacitors right at each heater pin (~200pf). 
   
  These are just suggestion,  the emi from the torroid is generally vertical,  so it sounds like when you put the lid on it gets bounced around and picked up but the OPT.  
   
  A plastic lid would be something to look for,   even plexiglass top with the sides from the stock case may be worth trying.   It is worthwhile to get rid of audible hum with Grados,  that seemingly benign low level hum adds significantly to the IMD. It is even worthwhile to get rid of non-audible 60hz hum because of its influence on IMD.  Has anyone done RMAA with/without the top on ?


----------



## jdkJake

Quote: 





funch said:


> Hey Jake, you gotta lay off the steroids.
> 
> 
> 
> ...


 


  Hellofatime for a 'roid rage, huh? 
	

	
	
		
		

		
		
	


	



   
  Thanks for the kind words regarding the case. Amazing how a bit of paint can perk something right up and turn it into something completely different and IMHO, quite elegant and modern.
   
  As for the LCD2's, let me get a bit more time on them before I comment on the overall sound. I will say this however, one of the strengths of this amp, at least for me, is the gain structure. The overall gain is quite low, even on the Hi-Z setting. As such, if you like it VERY loud or have a weaker source, you may find it more difficult to get all the volume and attendant power some phones tend to crave. I do not listen too loud, so, it is not much of an issue to me. I find I am maximizing the signal into the amp, which is always a good thing. It is also nice to get a wide range of travel out of the potentiometer. That said, one man's strength is another man's weakness. The amp might not have enough 'umph' for some phones and some listeners. The LCD2 may fall into that category, but, it is a bit early to tell. 
   
  With Grados however, this amp really, really shines. An open, dynamic and detailed sound that is never harsh or biting. Lot's and lot's of presence, soundstage and clarity that you can listen too all day long if it were not for the comfort issues with those damn Grado ear pads. 
	

	
	
		
		

		
		
	


	




 A really wonderful combination. For the price point, I suspect it would be difficult to find this level of refinement for Grados. 
   
  Good stuff.


----------



## jdkJake

Quote: 





glenda said:


> I have an spud amp that is similiar to this one.  It can be worthwhile to ground the heatsinks for the heaters,  they tend to pick up the EMI from the transformers ( I saw 60hz @ -90 reduced to -100db) and this was a separate chassis.  Another thing to try would be adding  decoupling capacitors right at each heater pin (~200pf).
> 
> These are just suggestion,  the emi from the torroid is generally vertical,  so it sounds like when you put the lid on it gets bounced around and picked up but the OPT.
> 
> A plastic lid would be something to look for,   even plexiglass top with the sides from the stock case may be worth trying.   It is worthwhile to get rid of audible hum with Grados,  that seemingly benign low level hum adds significantly to the IMD. It is even worthwhile to get rid of non-audible 60hz hum because of its influence on IMD.  Has anyone done RMAA with/without the top on ?


 

 Are you referring to the heatsink for the heater power supply? This design is using a DC heater supply. Certainly easy enough to try.
   
  BTW, this uses an E-I core, but, I get your point. The effect is the same in that RF starts bouncing around with the lid on. I agree a different material for the top would be one way to skin the cat. It would just be nice to get the current case to work if at all possible as it makes the build more approachable for a wider audience of builders.
   
  I will try a couple things later today once I get it back online. Are you thinking of a small ceramic to decouple the heaters?


----------



## jdkJake

Quote: 





tomb said:


> The Torpedo website is up and running!


 

 Wow! Great work on the Torpedo site TomB. Very impressive and most informative.
   
  Well worth the wait.


----------



## tomb

Quote: 





jdkjake said:


> Are you referring to the heatsink for the heater power supply? This design is using a DC heater supply. Certainly easy enough to try.
> 
> BTW, this uses an E-I core, but, I get your point. The effect is the same in that RF starts bouncing around with the lid on. I agree a different material for the top would be one way to skin the cat. It would just be nice to get the current case to work if at all possible as it makes the build more approachable for a wider audience of builders.
> 
> I will try a couple things later today once I get it back online. Are you thinking of a small ceramic to decouple the heaters?


 
  Thanks for the kind comments on the Torpedo website!
   
  Just an FYI about the discussion in the quote above - Dsavitsk and I have found that the bottom of the case contributes, too.
   
  Crappyjones123 - many thanks on your kind comments about the Beezar packing!  I've never had a damaged shipment, yet (knocks on wood!) and hope to keep it that way.


----------



## glenda

Quote: 





jdkjake said:


> Are you referring to the heatsink for the heater power supply? This design is using a DC heater supply. Certainly easy enough to try.
> 
> BTW, this uses an E-I core, but, I get your point. The effect is the same in that RF starts bouncing around with the lid on. I agree a different material for the top would be one way to skin the cat. It would just be nice to get the current case to work if at all possible as it makes the build more approachable for a wider audience of builders.
> 
> I will try a couple things later today once I get it back online. Are you thinking of a small ceramic to decouple the heaters?


 


 Yes a small ceramic right at the heater pin really helped mine,  this type of tube are notorious for oscilating by picking up HF off their pins.
   
   
  edit:  also yes I never would have thought about until I felt the dc heater supply hetsink vibrating,  grounding it quickly cured that.


----------



## UKToecutter

Glenda,
   
  Have you tried grounding all of the heatsinks?


----------



## funch

Quote: 





jdkjake said:


> Wow! Great work on the Torpedo site TomB. Very impressive and most informative.
> 
> Well worth the wait.


 


   x2.
   
  BTW, I see that C7/8 are optional, but can't seem to find any info on them.
   
  Jake - could the choke maybe have anything to do with the hum?


----------



## UKToecutter

Quote: 





funch said:


> x2.
> 
> BTW, I see that C7/8 are optional, but can't seem to find any info on them.
> 
> Jake - could the choke maybe have anything to do with the hum?


 


 x3


----------



## tomb

Quote: 





funch said:


> x2.
> 
> BTW, I see that C7/8 are optional, but can't seem to find any info on them.
> They are spec'd on the BOM as 470uf 10V.  I haven't found them to make any difference, but it might be that they could improve the performance of some tubes that I haven't tried.
> ...


----------



## funch

Thanks, tomb. I saw them on the BOM and schematic, but couldn't find why they were optional.


----------



## jdkJake

Quote: 





funch said:


> x2.
> 
> BTW, I see that C7/8 are optional, but can't seem to find any info on them.
> 
> Jake - could the choke maybe have anything to do with the hum?


 

 C7/8 are bypass/decoupling caps for the transistor bias LED. I threw them. Figured why not?
   
  I did not try the resistor, but, as TomB has posted, he seems to have better results with the choke. I do get a slight mechanical buzz from my choke, but, it does not telegraph into the audio circuit. You have to get your ear dangerously close to even hear it. Not recommended.


----------



## jdkJake

Quote: 





glenda said:


> Yes a small ceramic right at the heater pin really helped mine,  this type of tube are notorious for oscilating by picking up HF off their pins.
> 
> 
> edit:  also yes I never would have thought about until I felt the dc heater supply hetsink vibrating,  grounding it quickly cured that.


 

 Okay. I will have to see if I have a ceramic around that rating. I think I have a 100pf ceramic, but, not much beyond that. I know I have a film cap around that rating I could experiment with. Let me trudge through the parts bin and see what I can dig up.


----------



## dsavitsk

jdkjake said:


> Let this serve as a caution. The fuse drawer is apparently somewhat fragile. That or I am far more powerful than I ever knew. :eek:
> 
> So, be gentle on installation of that fuse!




Wow, I can't say I've seen that before.  I use a lot of these fuse drawers and have yet to have a similar issue.



glenda said:


> I have an spud amp that is similiar to this one.  It can be worthwhile to ground the heatsinks for the heaters,  they tend to pick up the EMI from the transformers ( I saw 60hz @ -90 reduced to -100db) and this was a separate chassis.  Another thing to try would be adding  decoupling capacitors right at each heater pin (~200pf).
> 
> These are just suggestion,  the emi from the torroid is generally vertical,  so it sounds like when you put the lid on it gets bounced around and picked up but the OPT.




The hum actually seems to be being picked up by the tubes which have no internal shielding -- they were originally meant for differential duty, so probably didn't need it. But, we have tried the transformers in the same cases with other tubes and not had an issue.

The heaters are grounded. There is a DC supply to pin 4 and a pin 3 is grounded. I am doubtful that the heaters are the issue, but you never know. C6 decouples the post regulator, so you could try increasing that. You could also decouple pin 4 right at the tube which would just entail putting a cap across pin 4 and 3.



funch said:


> How did the amp sound with the LCD2's?




Probably not an ideal combination as the LCD's turn out to have a lot of back EMF which makes driving them with a SET amp problematic.


----------



## dsavitsk

funch said:


> BTW, I see that C7/8 are optional, but can't seem to find any info on them.




The impedance of the bias supply is a function of the the source impedance to the transistor's base, and the Hfe (~Rs/Hfe). With the LEDs, the Source Z is ~11 Ohms. Since Hfe is ~300, that means that the bias Z is less than an Ohm. This impedance is multiplied by the mu of the tube and added to the Zout of the plate which is why keeping it low is important here -- especially as the rp of the 6J6 is not particularly low. 

But, bypassing the LEDs may lower this even more. We thought it was incidental, and neither of us could hear a difference. On the expensive version of this amp, I don't bypass.


----------



## jdkJake

Quote: 





dsavitsk said:


> Wow, I can't say I've seen that before.
> 
> 
> 
> ...


 
   
  Wild, huh?
   
  So, my grandfather (on my mother's side) was the ultimate DIY man. Built his own house, made knives/tools, grew/raised his own food. You name it, he did it. 
   
  My other grandfather (on my father's side) could not change a light bulb without risk of breaking it. Hell of a baker though.
   
  While both had most excellent qualities, I like to think I turned out more like my DIY grandfather. 
   
  That said, sometimes the recessive gene comes to the forefront just to remind you of where you come from.


----------



## liamstrain

Quote: 





> Tomb:
> As for the ground loop question - it's a good thought (not a silly question!), but we have tested the amp with the PCB completely isolated from the case and with no source connected.  It made no difference.


 
   
  In this case, the poster indicated that the hum ONLY appears when the case lid is on, when the PCB is isolated, there is no hum. So that's why I wondered if a drain from the case would correct it. 
   
  Sorry for posting about it in the other thread.


----------



## tomb

Quote: 





liamstrain said:


> In this case, the poster indicated that the hum ONLY appears when the case lid is on, when the PCB is isolated, there is no hum. So that's why I wondered if a drain from the case would correct it.
> 
> Sorry for posting about it in the other thread.


 

 No problem!  I just wanted to be sure that we all had the benefit of the discussions concerning the Torpedo.  Thank you for re-posting your comment. 
	

	
	
		
		

		
			




   
  About your comment though, maybe I'm not reading it correctly - or it could be semantics.  However, I think jdkjake was stating that there is no hum when it is uncased - iow, bare PCB sittting on a table.  That's slightly different than _isolated_.  What I stated in the Pics of Your Builds thread is that we (Dsavitsk) have definitely tested it isolated - in the case, buttoned up - but with no ground point on the PCB touching the case.  That made no difference.  As in, the hum was still detectable.  We've also found that the hum is still there - just not as detectable - when the lid is off, but when the PCB is sitting in the bottom half of the case.  So IOW, the case bottom contributes to the issue as well - just not as much.
   
  Admittedly, this is my own perspective from jdkjake and Dsavitsk (except for noting the hum with just the case bottom - that was me).  So, maybe they can confirm whether I've portrayed the scenarios correctly.


----------



## jdkJake

Quote: 





tomb said:


> About your comment though, maybe I'm not reading it correctly - or it could be semantics.  However, I think jdkjake was stating that there is no hum when it is uncased - iow, bare PCB sittting on a table.  That's slightly different than _isolated_.  What I stated in the Pics of Your Builds thread is that we (Dsavitsk) have definitely tested it isolated - in the case, buttoned up - but with no ground point on the PCB touching the case.  That made no difference.  As in, the hum was still detectable.  We've also found that the hum is still there - just not as detectable - when the lid is off, but when the PCB is sitting in the bottom half of the case.  So IOW, the case bottom contributes to the issue as well - just not as much.
> 
> Admittedly, this is my own perspective from jdkjake and Dsavitsk (except for noting the hum with just the case bottom - that was me).  So, maybe they can confirm whether I've portrayed the scenarios correctly.


 

 Yes, I am stating that in my situation, there is no hum when uncased - low, bare PCB sitting on the table. I have run it with just an iPod as an input to take out any other potential grounding and/or ground loop issues. 
   
  I had not noticed a hum with just the case bottom, but then again, the hum even with the top case on is extremely low. Certainly not a show stopper, but, rather something that would be nice to isolate and resolve to make the amp that much better.
   
  I have a set of 5964's to try out as well. Just kind of overloaded this weekend. Today is our annual "Pork Extravaganza" New Years feast, so, do not expect much from me today beyond a smile and a full belly.


----------



## vvs_75

[size=medium]I’ve been enjoying my Torpedo for two days, the more I listen to it the more I like it! 
	

	
	
		
		

		
		
	


	


[/size]
  [size=medium]I wanted it for my work rig, so it fits the purpose very well.[/size]
   
  [size=medium]In my case I would not call the hum as an “audible” hum at all. My ipod hiss is louder then the hum. It’s very low and I only can hear that its there when I move the top cover On and OFF while the amp is on (no music playing in complete silent room). [/size]
   
   

   
  [size=medium]I grounded the heat sinks during the build, so I can't  comment how much it does contribute or help with the hum. Also I am using a choke instead of R2 and vintage NOS ECC91 Mullard tubes.  My plates are very stable at 129/130 VDC.[/size]
   
  [size=medium]Thanks everybody who contributed to this project and happy building! 
	

	
	
		
		

		
		
	


	


[/size]


----------



## tomb

Quote: 





vvs_75 said:


> [size=medium]I’ve been enjoying my Torpedo for two days, the more I listen to it the more I like it!
> 
> 
> 
> ...


 

 Nice pics and glad you're enjoying it!  Maybe it really is focused primarily on that case lid (I assume that's what you meant when you typed "lead"), but I could swear I still heard it - not as much, though - with just the bottom.  Your feedback is much appreciated and thanks for trying the heat sink grounding.


----------



## vvs_75

Quote: 





tomb said:


> Nice pics and glad you're enjoying it!  Maybe it really is focused primarily on that case lid (I assume that's what you meant when you typed "lead"), but I could swear I still heard it - not as much, though - with just the bottom.  Your feedback is much appreciated and thanks for trying the heat sink grounding.


 

 I meant "lid, cover" not "lead" 
	

	
	
		
		

		
		
	


	




.


----------



## n_maher

You people and your fancy cases...


----------



## funch

OK, I'll bite. Where did that Hammond come from?


----------



## tomb

Quote: 





funch said:


> OK, I'll bite. Where did that Hammond come from?


 

 The Hammond was the case used for the early prototypes - about 7 of them.  They were "special" order, too - with an extrusion length of 13 inches.  Of course, none of them were custom machined.  What you see in the pic above was all Nate's own mill work.  Some of this is detailed in the Torpedo History on the Torpedo website.
   
  I still have several of the cases, but design changes after those first prototypes lengthened the PCB to 14 inches and it got wider, too.  That's one of the reasons we went to Context.


----------



## jdkJake

Not been a good week for me.
   
  Until the replacement arrives, I "fixed" my fuse drawer, reassembled everything and immediately blew a fuse. Measured less than 2ohm between B+ and ground.
   
  Luckily this design is so clean and straightforward. I lifted R5 and R4 to isolate the high voltage supply and still had the short. Not much was visible, everything looked to measure okay. I even lifted/removed a few other components to be sure that no solder/metal chip had worked it's way into anything.
   
  Turns out I was heavy handed once again. The center lug used for one of the bottom standoffs is right next to the main high voltage supply line to the amp portion of the board. I was using a stainless #4 flat washer at that location to bring the standoff to the correct height. Seems I torqued the screws a bit too tight and the washer pierced the solder mask. For that location, you might want to consider a nylon washer (which I have switched to using) or be careful not to over tighten.
   

   
  Anyway, back in business.


----------



## jdkJake

Probably wondering what the purple wires are in the picture above.
   
  I also went ahead and grounded all the heat sinks. I returned them back to the transformer ground pin (pin #6).
   

   
  Subjectively, it might have helped a little bit. Hard to say. I need to get some better test gear to help with measuring progress. I will work on that soonest.


----------



## jdkJake

Oh, and I also went ahead and decoupled the heaters.
   
  The only caps I had in the parts bin around 200pf were some wima 220pf film caps. So, in they went.
   

   
  No real change. BTW, note the nice use of nylon flat washers on the standoffs.


----------



## jdkJake

Oh, and one more thing.
   
  I decided to up the ante on the shield a bit. Never know what you have in the garage until you really start looking.
   

   
  That is steel. 3/16 flat steel 
	

	
	
		
		

		
		
	


	




. Wrapped in electrical tape.
   

   
  It was a b---- to cut clean. The Dremel with a cutting wheel did most of the work after my arm almost fell off trying to use a hack saw. Gotta love power tools. Still was too tall for the case to close correctly.
   
  In any case, it was mostly a cool experiment. Did not change anything, but, I want to try it further down a bit, closer to the output transformers. I'll let you know.


----------



## crappyjones123

Finished the build today. Powered on with no issues. Playing some tunes right now but I have a bad case of the hum with hd650s . Persists with ibuds as well. Just a constant volume hum that stays even with music playing. I have the a/c unit just on the other side of the door so it's not completely quiet of an environment and it is still quite bothersome. With music without quieter passages it's easier to forget about it but with a lot of my music where there are pauses it is quite noticeable. 
   
  Going to sleep now. Will try it tomorrow with the lid to see if it is indeed less that way. Will also try the choke instead of the resistor tomorrow. Just wanted to try to get a working project tonight. 
   
  Sq wise so far, it is extremely clean with dumont 5964 tubes. Oddly enough it sounds non tubey to me. Might be the tubes but coming from a warm lush amp it's a change of pace. Very very clean vocals. Barring the hum issue it is a pretty nice amp. Hopefully that issue gets sorted out soon. Excellent amp Doug. Thanks to Tom for the excellent kit.


----------



## dsavitsk

That sounds like a lot more hum than expected. With the lid off, it should be basically inaudible. Putting the lid on increases it some, but if it is to the level of quite bothersome, then something else is likely going on.


----------



## DingoSmuggler

Quote: 





crappyjones123 said:


> Finished the build today. Powered on with no issues. Playing some tunes right now but I have a bad case of the hum with hd650s . Persists with ibuds as well. Just a constant volume hum that stays even with music playing. I have the a/c unit just on the other side of the door so it's not completely quiet of an environment and it is still quite bothersome. With music without quieter passages it's easier to forget about it but with a lot of my music where there are pauses it is quite noticeable.
> 
> Going to sleep now. Will try it tomorrow with the lid to see if it is indeed less that way. Will also try the choke instead of the resistor tomorrow. Just wanted to try to get a working project tonight.
> 
> Sq wise so far, it is extremely clean with dumont 5964 tubes. Oddly enough it sounds non tubey to me. Might be the tubes but coming from a warm lush amp it's a change of pace. Very very clean vocals. Barring the hum issue it is a pretty nice amp. Hopefully that issue gets sorted out soon. Excellent amp Doug. Thanks to Tom for the excellent kit.


 

 To me your hum issue sounds somewhat worse than other peoples, perhaps a ground loop issue?
  What's you're source, could its signal ground be connected to AC ground?  Can you try with a different source?
   
   
  in other news...
  ...I'm still waiting for Auspost to send a kangaroo over from sydney to perth with a torpedo kit in its pouch.
  If the kangaroo survives the long trip across the nullarbor, i might see my amp this afternoon at best, or maybe tomorrow if its an older kangaroo.
  Lets just hope they haven't sent a wombat, or I'll be waiting a long while - damn equal opportunity laws.


----------



## Gabe Logan

The only hum i hear is during startup but after that it fades away and it is very quiet.


----------



## tomb

Quote: 





crappyjones123 said:


> Finished the build today. Powered on with no issues. Playing some tunes right now but I have a bad case of the hum with hd650s . Persists with ibuds as well. Just a constant volume hum that stays even with music playing. I have the a/c unit just on the other side of the door so it's not completely quiet of an environment and it is still quite bothersome. With music without quieter passages it's easier to forget about it but with a lot of my music where there are pauses it is quite noticeable.
> 
> Going to sleep now. Will try it tomorrow with the lid to see if it is indeed less that way. Will also try the choke instead of the resistor tomorrow. Just wanted to try to get a working project tonight.
> 
> Sq wise so far, it is extremely clean with dumont 5964 tubes. Oddly enough it sounds non tubey to me. Might be the tubes but coming from a warm lush amp it's a change of pace. Very very clean vocals. Barring the hum issue it is a pretty nice amp. Hopefully that issue gets sorted out soon. Excellent amp Doug. Thanks to Tom for the excellent kit.


 

 I would agree with the others that something else must be going on. It may be that set of tubes is bad. Have you tried a different set?  Also, this is pure conjecture, but after having built 3 of these so far, it seems that there is a bit of burn-in that goes on.  When I finished the production version in this thread, I was alarmed at the hum I first heard.  However, it's never been as bad since and subsided to the level of minor-nuisance that everyone seems to be confirming. I can't offer a technical explanation for it - maybe the transformers quieten down after a few hours.
   
  If it doesn't improve appreciably, though, please post again. We may need to investigate other possibilities for you.
   
   
  P.S. For the same reason the tubes pick up interference from the transformers, it also means they are pretty susceptible to adjacent power sources. If you have the Torpedo next to a CD player/receiver/PC/etc.where the item's transformer is located, it will definitely pick up the hum.


----------



## crappyjones123

The amp is located next to quite a bit of electronic equipment. I will try the amp in a quiter place when I get home today. Last nights tests were with an iPhone and iPad yielding identical hum levels. This morning I tried te amp without the top cover on and the noise was reduced a LOT. i can still hear it over the ac but it was a lot less than with the case on. I'll try grounding the heatsinks after a different set of tubes and a few different sources. 
   
  A few observations on construction -
   
  1. Place the warning regarding grounding the volume pot a little earlier for impatient twits like me.  fat fingers and tight spaces don't like each other. 
   
  2. It might be better to test how many spacers are needed for the standoffs prior to board population. As of right now the screw that is going in from the bottom of the case sticks out too much from the bottom as most of the spacer is taken by the pcb screw. 
   
  None of the above are mission critical and require better planning on the builders part. Just my thoughts on the process.


----------



## jdkJake

Quote: 





crappyjones123 said:


> The amp is located next to quite a bit of electronic equipment. I will try the amp in a quiter place when I get home today. Last nights tests were with an iPhone and iPad yielding identical hum levels. This morning I tried te amp without the top cover on and the noise was reduced a LOT. i can still hear it over the ac but it was a lot less than with the case on. I'll try grounding the heatsinks after a different set of tubes and a few different sources.


 

 When you try your tests with the cover on and the HD650, please leave the volume level ALL the way down (full attenuation) and note the hum level with  BOTH positions of the front panel impedance switch.
   
  I suggest you float the inputs (nothing connected) when you make your observations. That will eliminate the potential for any ground loops whatsoever.
   
  Try the above in the quietest room available.
   
  Thanks.


----------



## crappyjones123

650s plugged in. high impedance. no source. volume all the way down first. then volume all the way up. as quiet as i will have a listening environment. 
   
  case on - hum as before. 
   
  case off - very low hum but audible nonetheless even with the a/c unit going outside the door. but now i can hear white noise and little staticy sounds. probably the tubes. but it sounds like wood crackling. the staticy noise is not constant like the hum. comes and goes. 
   
  hum gets more prominent, with and without the case when the volume is turned up. 
   
   
  all the above conditions but this time a battery powered macbook air is used for a source. same observations as above. 
   
   
  low impedance and same conditions as above
   
  case off - no audible noise or hum with the volume pot turned all the way down. the hum is audible with the volume pot all the way up. 
   
  case on - the hum returns with the case being held an inch above where it sits. stays at the same level regardless of the position of the volume knob. 
   
  same set of tubes as last night. i figured i'd post this just in case someone can troubleshoot from the above clues. has anyone noticed improvement with high z phones after using the choke vs the resistor at R2?


----------



## HiGHFLYiN9

Quote: 





n_maher said:


> You people and your fancy cases...


 

 Haha, good to see you on here Nate! Yours is very pretty too, and unique!


----------



## tomb

Quote: 





crappyjones123 said:


> 650s plugged in. high impedance. no source. volume all the way down first. then volume all the way up. as quiet as i will have a listening environment.
> 
> case on - hum as before.
> 
> ...


 
  Your tubes are bad.  Contact me via e-mail or Beezar and I'll send you a replacement set.  The intermittent static/crackling is pretty much a confirmation.  Although, you should be able to confirm this yourself by swapping them out.
   
  Actually, the hum should be even quieter with high z phones and yes, I do believe the choke makes it quieter - regardless of impedance.  If you read closely in this build thread or on the website, you'll see that I recommend the choke, period.


----------



## jdkJake

Quote: 





crappyjones123 said:


> 650s plugged in. high impedance. no source. volume all the way down first. then volume all the way up. as quiet as i will have a listening environment.
> 
> case on - hum as before.
> 
> ...


 


  Okay. You are getting different results from my unit. Something appears to be different.
   
  When I use HD650's with no source and the case employed, the volume setting (attenuation setting) makes no difference in the quantity of the hum. The amp is dead quite, save for the hum, at any volume setting**. Only changing the impedance switch changes the relative volume of the hum, which, is louder on the high impedance setting with the HD650. Removing the case top makes it quieter and removing the bottom, quieter still. So far, this is the only headphone that has allowed me to hear the bottom of the case make a difference. Totally uncased, the amp is truly dead quiet regardless of headphone (at least of what I own), impedance setting or volume setting.
   
  I think you have something else going on if you hear a hum with the unit uncased. Especially if it changes with the attenuator setting. Have you tried out a different set of tubes? Any pictures of the board to share?
   
  BTW, I am using the choke. Have not tried a resistor at R2 yet.
   
  **note, I did have one HIGHLY microphonic 6J6A, which, picked up just about anything that came near the tube. You could tap the table the amp was on and hear it. Tapping the tube directly (gently) was seriously loud. It was also 'staticy'. That went away with a different 6J6A tube.


----------



## jdkJake

On a different topic, I have been running 5964 tubes (Sylvania-labeled Gold Brand) the last couple of days. They are very nice and are a bit different in presentation from the Westinghouse-labeled 6J6A I had also been using. The Sylvania are quite a bit more extended and detailed on the high-end. Not necessarily thinner, but more high-end focused while retaining plenty of low-end presence and control.  The 6J6A seem a bit more, lacking for a better word, robust. As TomB has remarked previously, the 6J6 seem to be a bit more dynamic as well. Either one is a fine tube and it really comes down to personnel preference. 
   
  I will say this much about the 5964 I am using, the first pair I put into the amp measure very close on the plate (122.7/121.3). Closest so far right out of the box. I will have to check/measure for how close they actually match in output, but, they seem quite close on subjective listening.
   
  Good stuff.


----------



## DingoSmuggler

OK package arrived yesterday, and things got underway. Thanks to TomB for the great packaging. I'll be popping bubble wrap for weeks
	

	
	
		
		

		
			




   
  Soldering to the vias connected to the ground plane on this thing was certainly interesting. That massive ground plane sucks heat away faster than you can say _torpedo_. Mincy lil' 25W irons need not apply.
  One of those tube sockets gave me a hell of a time, but i managed to get it as straight as i possibly could, although its still a bit wonky. Also its pin 4 hole is half closed over, but i've tried plugging and unplugging tubes, and it seems to still work fine.
  Got to buy some M3 fasteners today and I should be able to finish things off.


----------



## crappyjones123

I replaced the tubes today with ge 5844s and I can't hear any hum without the top cover and the impedance switch at low. At high I can hear it but it is low. Low enough to where I can kinda hear it throughout the range of the pot with no source. With an iPhone as source, it is there but I can't hear the hiss of the iPhone anymore. I'm guessing the hiss was from the old tubes not the source as I can't hear any static or pops that I heard with the dumont set. Also left the amp on today and will do so tonight so whatever needs to settle, does so. Sound with the 650s is tight and clean. No distortion with the volume pot at 12 o'clock (I can't go higher than that) without hurting myself. 
   
  The top cover is being made prettier (I hope) so I will see how it behaves with the case on and the new tubes. Hopefully I will have time tomorrow to install the choke as well. 
   
  I realize there is no subjective way to explain what I hear but the hum is certainly a lot less than what I had with the previous set of tubes (thanks for catching that Tom). 
   
  For now it plays music  Quite well.


----------



## tomb

Quote: 





dingosmuggler said:


> OK package arrived yesterday, and things got underway. Thanks to TomB for the great packaging. I'll be popping bubble wrap for weeks
> 
> 
> 
> ...


 
  I'm sorry about that tube socket.  The quality control is not so good sometimes.  They're wrapped in that wax paper stuff when I get them from China and I don't have time to check them all.  Every once in a great while, the ceramic gets molded badly and the tube pin holes get covered up, as you stated.  I would recommend the tip of a sharp knife such as an X-acto.  Ream the hole out by twirling the tip of the knife in the hole.  You have to be careful, though, if it's bad enough you could crack the entire top half of the socket.  If it's unsuitable, let me know and I'll send you another.


----------



## tomb

Quote: 





crappyjones123 said:


> I replaced the tubes today with ge 5844s and I can't hear any hum without the top cover and the impedance switch at low. At high I can hear it but it is low. Low enough to where I can kinda hear it throughout the range of the pot with no source. With an iPhone as source, it is there but I can't hear the hiss of the iPhone anymore. I'm guessing the hiss was from the old tubes not the source as I can't hear any static or pops that I heard with the dumont set. Also left the amp on today and will do so tonight so whatever needs to settle, does so. Sound with the 650s is tight and clean. No distortion with the volume pot at 12 o'clock (I can't go higher than that) without hurting myself.
> 
> The top cover is being made prettier (I hope) so I will see how it behaves with the case on and the new tubes. Hopefully I will have time tomorrow to install the choke as well.
> 
> ...


 
  I'm glad it's better.  As I said, the static and pops were definitive that it was the tubes.  There's no way you should be hearing that on the Torpedo.
   
  I got your address and I'll have another pair shipped out to you on Friday.


----------



## crappyjones123

Mom just walked in the door. Saw the topless torpedo and asked what it was. Naturally, I asked her to sit in my chair and gave her my headphones. 
   
  "Oh wow! This sounds nicer than my headphones [iBuds]. How much did it cost?" 
   
  $XXX.XX
   
  "WHAT??? DO YOU KNOW HOW MANY HEADPHONES I COULD BUY FOR THAT MUCH MONEY???" 
   
  Good thing she doesn't know how much the jh16s cost


----------



## DingoSmuggler

Quote: 





tomb said:


> I'm sorry about that tube socket.  The quality control is not so good sometimes.  They're wrapped in that wax paper stuff when I get them from China and I don't have time to check them all.  Every once in a great while, the ceramic gets molded badly and the tube pin holes get covered up, as you stated.  I would recommend the tip of a sharp knife such as an X-acto.  Ream the hole out by twirling the tip of the knife in the hole.  You have to be careful, though, if it's bad enough you could crack the entire top half of the socket.  If it's unsuitable, let me know and I'll send you another.


 

 Cheers for the offer, but i think it will be ok. I can still plug a tube in, so I'll just leave as is.


----------



## DingoSmuggler

Got everything soldered up, cleaned, pre turn on checks....
  ....switch her on and nice glow from tubes, no glow from LEDs 
  checked B+ and no voltage. turn it off and waited 20 minutes
  came back, measured a few things, the high volt secondary of the power transformer is reading about a meg ohm resistance  
   
  i'll desolder it and see if reflowing the terminations on the lead-outs fixes things, but i fear the worst for this tranny


----------



## jdkJake

Quote: 





dingosmuggler said:


> Got everything soldered up, cleaned, pre turn on checks....
> ....switch her on and nice glow from tubes, no glow from LEDs
> checked B+ and no voltage. turn it off and waited 20 minutes
> came back, measured a few things, the high volt secondary of the power transformer is reading about a meg ohm resistance
> ...


 

 I would be surprised if the tranny itself is damaged. They are pretty robust.
   
  Measure the resistance between B+ and ground. The ground pad next to B+ is nice and handy. I would be surprised if you did not have a short.
   
  Any pics?


----------



## DingoSmuggler

Quote: 





jdkjake said:


> I would be surprised if the tranny itself is damaged. They are pretty robust.
> 
> Measure the resistance between B+ and ground. The ground pad next to B+ is nice and handy. I would be surprised if you did not have a short.
> 
> Any pics?


 
  B+ to ground is 238k ohms, which seems to be right to me.
   
  The secondary winding of the tranny at my guess should easily be under 1k ohm, 1meg ohm is definitely not right
   
  i can't get pics tonight, will have to be tomorrow for those
   
   
  i managed to reflow the lead-out connections for the high volt secondaries on the transformer without desoldering it, but this didn't help things.


----------



## jdkJake

Quote: 





dingosmuggler said:


> B+ to ground is 238k ohms, which seems to be right to me.
> 
> The secondary winding of the tranny at my guess should easily be under 1k ohm, 1meg ohm is definitely not right


 

 True. I am measuring ~256 ohm across the high voltage secondary.
   
  While hard to verify once solder into the board, you should be able to visually verify the wires coming out of the transformer and wrapping onto the pins.


----------



## dsavitsk

I bet that there is a cold solder joint on the transformer itself. The wire they use to wind transformers is enamel covered, and if the manufacturer did not do a good enough job stripping the enamel, then the wire could be "soldered" to the pins, but not actually connected. If this is indeed what happened, repairing it will be a pain, but much less of a pain than trying to desolder the whole transformer -- ask me how I know that 

So, take a look at the pins and see how good that solder connection is.


----------



## DingoSmuggler

Quote: 





dsavitsk said:


> I bet that there is a cold solder joint on the transformer itself. The wire they use to wind transformers is enamel covered, and if the manufacturer did not do a good enough job stripping the enamel, then the wire could be "soldered" to the pins, but not actually connected. If this is indeed what happened, repairing it will be a pain, but much less of a pain than trying to desolder the whole transformer -- ask me how I know that
> 
> 
> 
> ...


 

 I'm not going to ask 
	

	
	
		
		

		
		
	


	



   
  Yes this was one of my suspicions, and what i meant by "reflowing the lead-out wires" - but of all the joins on the transformer, these ones are the most obscured by other components, so I couldn't really see how bad the factory solder job was, or how much my reflowing of the joins was helping...
   
  I had made an attempt at desoldering the transformer, and was left humbled. I think i will have better success removing the choke and C1 to give me some room to play, and try to fix the transformer in situ as you suggest.


----------



## tomb

I was waiting for Dsavitsk to respond - he is the authority, including/especially about the transformers.  It sounds like he has a good suggestion and we appreciate it if you are willing to work with it.  This is especially true because you're international and shipping won't be cheap or quick.  So, many thanks if you can try what Dsavitsk suggests.  However, don't keep trying long enough to get frustrated or even damage the transformer.  Of course, I will send you another one if it comes to that, but we'll need yours back to return to Edcor (I'll pay for shipping).


----------



## dsavitsk

dingosmuggler said:


> I had made an attempt at desoldering the transformer, and was left humbled.




The trick seem to be to add a ton of flux the joint and add some to your desoldering braid, then suck out the solder from each pin in turn. It is also a good idea to do the ones connected to traces first as then the excess weight will be on the pins that don't matter so much.

Also, I find it helpful to use a flat heat screw driver to pop each pin once all the solder that can be is removed.



tomb said:


> but we'll need yours back to return to Edcor (I'll pay for shipping).




Bah -- don't bother. I am sure Edcor will replace it, and if not, I'd rather eat the cost than force you to ship a bad part half way around the world.


----------



## DingoSmuggler

OK, I've got a plan of action now.
  Given the time zone differences, should hopefully provide an update while you're all happily sleeping


----------



## liamstrain

Quote: 





dsavitsk said:


> Bah -- don't bother. I am sure Edcor will replace it, and if not, I'd rather eat the cost than force you to ship a bad part half way around the world.


 

 I just needed to comment here. Classy. Seriously. Big points to all of you for being willing to get this right for him.


----------



## glenda

You could try gently sanding the enameled wire with a file then solder a jumper down to the pin.


----------



## DingoSmuggler

So i removed C1 and the choke which gave me room to work, so i decided to get desoldering braid in there so i could se how much winding wire was there. There was about 2 or 3 turns of winding wire wrapped on each post and it was definitely well tinned. Soldered them back up and it still reads open circuit.


----------



## tomb

I will do my best to get a transformer in the mail to you tomorrow.  I'm pretty sure I know who you are, but PM me your address, just in case. 
	

	
	
		
		

		
		
	


	



   
  EDIT: Shipped yesterday.


----------



## looser101

Don't know what it is about my build that may be different, but I can't detect any hum.  Had it out to a mini meet last night and no one could hear any either.  Sounds great with Grados, and can drive a K340 even though it could use a bit more gain (for quiet recordings).  Thanks to Tom and Doug for making it easy to build, by providing us with a kit.


----------



## dsavitsk

looser101 said:


> Don't know what it is about my build that may be different, but I can't detect any hum.




Interesting. Could you post details and perhaps some closeup pics of the tubes you are using?



looser101 said:


> even though it could use a bit more gain (for quiet recordings).




Unofficially, if you jumper pins 1 and 2 on the OPT, you can eek out a tiny bit more gain -- the transformer has a 10K primary, but I had them wind them such that pin 2 is a 7.5K. tap. The difference is pretty small - changing from a 18:1 voltage stepdown to a 15:1, and it does it at the expense of perhaps a little more distortion. But, if you just need a tiny bit of gain, it might make enough difference. Anyhow, I've never tried this, so do it at your own risk.


----------



## looser101

The only way I deviated from Tom's build is the physically smaller coupling caps and the volume pot is ungrounded.  C7/C8 not populated.
   

   

   

   
  Neither of these tubes hum.  Rogers (Mullard) 6J6 on the left and RCA 5964 on the right.  They're the only two pairs I have.
   

   

   

   

   
  Thanks for the tip on the output transformer taps, Doug.  May be useful in the future.


----------



## tomb

Quote: 





looser101 said:


> Don't know what it is about my build that may be different, but I can't detect any hum.  Had it out to a mini meet last night and no one could hear any either.  Sounds great with Grados, and can drive a K340 even though it could use a bit more gain (for quiet recordings).  Thanks to Tom and Doug for making it easy to build, by providing us with a kit.


 

 As Dsavitsk has also remarked, this is very interesting.  I don't think it's the tubes by looking at your pics.  I've half suspected whether there was some variance in the PTs (Power Transformer) from Edcor.  The extent of the hum seemed to vary among my 3 prototypes, for instance.  One of the things Dsavitsk tested was swapping the PT in my production prototype for one of the earlier PT's that was slightly different.  It made no difference as far as I can tell.
   
  Yet - maybe you got a quiet PT, while crappyjones got a noisy one (although it sounds like the tubes might be the culprit), and the rest of us somewhere in the middle.  Then DingoSmuggler gets one that doesn't work at all.  Interesting ... maybe ...   I've asked Dsavitsk if he's had more talks with Edcor - it may be warranted in light of some of this feedback.
   
  We appreciate all the work from you guys and the many comments.  My hopes are high that we can lick this eventually.  As several of you have noted, the amp sounds pretty dang good in spite of it.


----------



## HiGHFLYiN9

Curious... I wonder if raising the tubes up out of the chassis would alleviate any noise. It would require cutting a piece of aluminum to a suitable size rectangle, putting a pair of holes in it to accept two chassis mount 7 pin tube sockets, mounting it on a pair of standoffs that are drilled to the PCB, and running the corresponding wires from the PCB to the sockets. Might take an hour or two and about $10 in parts... any thoughts?


----------



## DingoSmuggler

I've decided to hack together a basic magnetometer for measuring magnetic fields around my torpedo (once it gets its new transformer).
  I'm just going to hook a _linear_ hall effect sensor (powered from a 9V battery -> 5V reg) to my multimeter and measure AC voltage which should give an indication of the strength of the AC magnetic field at the sensor.
  Not sure if it's going to work that well for this purpose - but at a parts cost of under $5, i figured its worth a shot.
  If it gives any useful info, i will share it on here.


----------



## dsavitsk

highflyin9 said:


> Curious... I wonder if raising the tubes up out of the chassis would alleviate any noise.




Interesting thought. Something like this perhaps.



The tube sockets are rotated slightly to make the pins line up. Only thing to think about is that you might want to remove the grid stoppers on the PCB, but put stoppers on the socket. Email me if you want the FPE file. I may give this a try at some point if no one else does.



dingosmuggler said:


> I've decided to hack together a basic magnetometer for measuring magnetic fields around my torpedo (once it gets its new transformer).




Interesting. I look forward to see what you find. The crude way to test this is to build the whole amp except for the OPTs. Then, hook up an OPT to some phones and move the transformers around and listen for hum.


----------



## HiGHFLYiN9

I think I'll give it a shot. I modified the FPE file a little bit in the interest of making it a permanent install (3mm thick and extra mounting holes for rigidity). Even if it doesn't make a difference with the noise, I like to see the tubes.


----------



## Rescue Toaster

From my experience with Edcors, the output transformers (XSM's in my case) are quite magnetically 'active' if you will. They are VERY susceptible to external magnetic fields (was seriously affecting my dynamic range/SNR in RMAA until I moved the power supply 2-3 feet away). Also mine 'sing' like crazy when playing test tones. I need to get some rubber grommets in place to try to isolate them from the chassis, see if that helps. I don't remember them doing that in the past, but I did have them on a wood breadboard, rather than bolted to an aluminum chassis, so maybe that is making the difference now.


----------



## jdkJake

Quote: 





rescue toaster said:


> Also mine 'sing' like crazy when playing test tones.


 

 Funny, I noticed that as well.


----------



## DingoSmuggler

Thanks Dsavitsk for the desoldering advice, i had been using flux when i was struggling, but it was a no-clean flux and didn't seem to work the best with the braid i had - which already had rosin flux in it.
  I got some liquid rosin flux and some fresh braid, followed your advice and was all done in 5 minutes. Orders of magnitude easier than the struggle before. 
	

	
	
		
		

		
			




   

  Replacement transformer for the faulty one was received today, thanks Tom.
   
  Another torpedo complete and ready for launch...
   

   
  In case someone was going to ask, the little blue parafeed caps there are 4.7uF jantzen standard z-cap (about $3.70 from partsexpress)
  otherwise a pretty much standard bom.
   
  A point that other builders might find useful is that all hardware I used is M3-0.5, so those from countries where metric is more readily available that's a good option - it will have about 5% less wiggling room that #4 screws, but all the holes line up good so that extra leeway didn't seem to be needed. If tapping the front/rear panel holes for M3 though you will need to enlarge the holes with the correct pilot drill.
   
  The tubes in the pic are GE 6J6s, the left one though had a bad case of electron tubicus microphonicus 
	

	
	
		
		

		
		
	


	



  change the volume, piiiiiiing! click my mouse, piiiiiing! tap my foot on the ground, piiiiing! tap the case, piiiiiiiiiiiiiiiiiiiiing!
  And Tom, don't worry about it mate, got plenty of others.
   
  So swapped in my 5844s. Man this amp sounds epic with MSpros. Sounds good with other cans too 
  Not going to try and say too much without spending more time with it.
  I'll try to get some good pics next week.


----------



## HiGHFLYiN9

I made a cool little logo for an engraved plate for my build. Feel free to swipe it.


----------



## tomb

Wow!  That's very cool!


----------



## DingoSmuggler

Here's a pic of my torpedo after i gave the top a coat of wrinkle paint(VHT wrinkle plus).
  It's a nice effect, good looks and feel, will do the bottom the same when i get a chance.
   
  also, loving the sound of the amp


----------



## tomb

Wow - very nice!


----------



## HiGHFLYiN9

Finished up yesterday:
   

   
  As you can see, the tubes were mounted on the plate mentioned above so they would stick outside of the chassis. There is a smidge of audible noise that sounds like it's from flux interaction, but it's barely audible and hardly worth mentioning; this was tested with a headphone with 32ohm impedance. I'd definitely consider it a non-issue. 
   
  I strayed from the BOM just a little bit with Kiwame resistors, gold plated Neutrik jack, standard RCAs and ClarityCap ESAs for parafeed duty. 
   
  Sounds great so far! Looking forward to some more critical listening this weekend.


----------



## liamstrain

Hah. That looks great. Fun to see everyones interpretations.


----------



## tomb

Quote: 





highflyin9 said:


> Finished up yesterday:
> 
> 
> 
> ...


 

 That's a great steampunk look!  Very, very neat!


----------



## jdkJake

Nice work HiGHFLYiN9. Very original and extremely well executed.
   
  An chance of a pic of the board and assembly you built to elevate the tubes?


----------



## funch

All together now!  'We Want Pix!  We Want Pix!'


----------



## HiGHFLYiN9

Ask and ye shall receive


----------



## n_maher

Quote: 





highflyin9 said:


> Finished up yesterday:


 

 Nice work as usual Bryan.


----------



## HiGHFLYiN9

Quote: 





n_maher said:


> Nice work as usual Bryan.


 
  Thanks Nate!
   
  Anyone else finish up their Torpedos? We need some fresh new pics


----------



## soundlikes

Any reviews on this amp??? SQ, soundstage, synergy with some cans ??? I want to know how good this amp drives AKG 70x or Q701s.....


----------



## tomb

Quote: 





soundlikes said:


> Any reviews on this amp??? SQ, soundstage, synergy with some cans ??? I want to know how good this amp drives AKG 70x or Q701s.....


 

 There are several impressions already in this thread.  That said, Dsavitsk is working hard on a solution to the ripple/hum.  We hope to have some news in a few weeks, perhaps.


----------



## UKToecutter

waiting with baited breath...........


----------



## mosshorn

Can't wait to hear about the progress! Been thinking of building this for a while


----------



## soundlikes

.... Torpedo !!!!!!


----------



## dsavitsk

Prototype boards have arrived. Now Tomb just has to find a little free time to build one and see how they work.


----------



## jdkJake

Now that's interesting. Same form factor?


----------



## J-Pak

Quote: 





dsavitsk said:


> Prototype boards have arrived. Now Tomb just has to find a little free time to build one and see how they work.


 


 What's changed in the new revision?


----------



## dsavitsk

Form factor is the same. Basically we switched to a new and much nicer power transformer. This required altering the power supply a bit and moving some components around, but we were careful to keep the tubes and all panel components in the same spots, so the case won't change. We are hopeful that this fixes the hum issue -- though, I should reiterate that the hum issue is really less of an issue than I think people believe.


----------



## tomb

Quote: 





> a new and much nicer power transformer


 
  = toroid.


----------



## jdkJake

dsavitsk said:


> I should reiterate that the hum issue is really less of an issue than I think people believe.




I agree that is true for low impedance cans using the low impedance tap, especially grado's. Using high impedance cans on the high impedance tap, like an HD650, makes the issue more pronounced. At least on my build.

Looking forward to seeing the changes.


----------



## J-Pak

Any updates? Thanks


----------



## soundlikes

I demand updates ... summer is here and I need a new project !!!!!!!!!!!!


----------



## jdkJake

The natives are restless... 
   
  And rightly so. The current version, with the lid off, is THE go-to Grado amp for me.
   
  Something about it and the HF-2's. The amp just disappears and the music comes to the forefront, as should be. An almost organic quality to the pairing. A most excellent combination. That much is for sure. 
   
  Makes you wonder how far a parafeed design can take you....


----------



## tomb

The new transformer is in hand, along with the PCB's.  I have the parts on order.  So, it should only take a weekend when I'm free to have some results.


----------



## tubey1

Quote: 





dsavitsk said:


> Form factor is the same. Basically we switched to a new and much nicer power transformer. This required altering the power supply a bit and moving some components around,


 
   
  Quote: 





tomb said:


> The new transformer is in hand, along with the PCB's.


 
  Does the BOM currently appearing on DIYforums.org and the current PCB on beezar reflect the changes to power supply and power transformer Doug is talking about? I just wanted to make sure before I submit an order with Mouser.


----------



## dsavitsk

No, not yet. Tom has been super busy lately, so we are still in a holding pattern. We'll update this thread as soon as we have tested and approved the changes.

To be more specific, the version with the toroid, assuming all goes well, will lose the choke, and the PS cap complement will change a little.


----------



## tomb

I am building it this weekend, hell or high water!!
   
  Yes, we have both been busy.


----------



## tomb

OK - I got almost everything done except the big stuff, and I'm only waiting on C3.  Mouser backordered it on me but I never noticed because I was concerned about the NJM regulator.  I got that from Dsavitsk, but I have a different C3 on order and it's already shipped.  So, it should only be a couple of more days ...
   
  EDIT: C3 is a 50uf 400V cap on the V2 PCB.


----------



## jdkJake

Pics TomB, pics!

The masses, including myself, are starving!


----------



## tomb

Quote: 





jdkjake said:


> Pics TomB, pics!
> The masses, including myself, are starving!


 
  I am only waiting on C3, the coupling caps (both in transit), and installing the transformer.  I'm saving the transformer for last, because I didn't want that shotput flexing the board while I still have parts to install.


----------



## HiGHFLYiN9

I really enjoyed building my first one, it's easily the best amp I've heard in it's price range. Dsavitsk, would a balanced drive option be worthwhile running two of these new boards in parallel... or would it be an act of pointlessness?


----------



## tomb

I can't answer the specific question you've posed to Dsavitsk, but you may enjoy seeing these:






   
  EDIT: Fixed 2nd pic link ...


----------



## HiGHFLYiN9

Looks splendid, you guys are doing the DIY community a great service by offering this amp at such a low cost.


----------



## KimLaroux

It carries it names really well. It does look like a torbedo. What are the dimentions of the outside case?
   
  The second link is dead, by the way.


----------



## jdkJake

Nice pics TomB!

I think you already know what the next question is going to be....


----------



## dsavitsk

highflyin9 said:


> Dsavitsk, would a balanced drive option be worthwhile running two of these new boards in parallel... or would it be an act of pointlessness?




I'm going to have to say pointless. There are many ways to build a balanced tube amp, but that really is not one of them.


----------



## tomb

Quote: 





kimlaroux said:


> It carries it names really well. It does look like a torbedo. What are the dimentions of the outside case?
> 
> The second link is dead, by the way.


 
  fixed ...
  Quote: 





jdkjake said:


> Nice pics TomB!
> I think you already know what the next question is going to be....


 
  Yes - dsavitsk and I are still working on it.  The toroid reduced the noise by about 90%.  Unfortunately, it's still detectable in _certain_ headphones.  We are going to try a few other specific things and let you know.  I should have one of those things tried out this weekend and have the results.


----------



## chiguy

Sorry to bump an old thread.  Has there been any updates on this?


----------



## tomb

I'm in the process of sending my toroid prototype over to Dsavitsk (it's taken awhile - been quite busy with non-headphone stuff, dang it!).  He has a solder-desolder re-work station that has more capability than my equipment.  I can't get the OT's removed without trashing them and the latest thing we were trying is to shield the OT's, which will require their removal.  That's about as much as I can tell you right now.


----------



## soundlikes

My fat wallet is waiting .... and the soldering iron is getting rusty !!!!!


----------



## tintin220

Having finally gone through this whole thread, I must say.. once the new kits are released with the toroid, I will probably be getting myself one of these to pair with my Magnums.


----------



## DingoSmuggler

Still using mine almost everyday, its a fantastic amp.


----------



## dsavitsk

chiguy said:


> Sorry to bump an old thread.  Has there been any updates on this?




Not an old thread, just a slow one. We are hopeful for some answers soon ...

... which I think we've said before. Rest assured that we are working on it, and if we hit a point where we aren't, we'll let people know.



dingosmuggler said:


> Still using mine almost everyday, its a fantastic amp.




Great to hear


----------



## cubeasic

Hallo,
   
  I come from the solid-state department and would like to build the torpedo as a first tube project.
  Since I alway wanted to built a point-to-point setup (I always admired the raw beauty of that), I wonder if there is any chance that the short kit is also available without case and pcb?
  The custom transformers seem mandatory for this amp.
   
  I guess, by building a separate enclosure for powersupply and amp, one can easily avoid the humming problem that may occur and still use the EI-core trafos.
   
  Regards
  Flo


----------



## tomb

Quote: 





cubeasic said:


> Hallo,
> 
> I come from the solid-state department and would like to build the torpedo as a first tube project.
> Since I alway wanted to built a point-to-point setup (I always admired the raw beauty of that), I wonder if there is any chance that the short kit is also available without case and pcb?
> ...


 
  We've reduced the hum significantly through the use of a toroid PT.  I'm not sure whether we'll ever eliminate it completely with certain headphones, but that's not that unusual for tube amps in this price range.
   
  Yes, the custom transformers are mandatory for this amp.  Since the short kit from Beezar only contains the case, the PCB, and the transformers, you're essentially asking if you can just purchase the transformers.  I think not, because we don't have "extra" stock.  Besides, they are custom fabricated not only for the winding/turns ratios, but also for a PCB.  The only connections are PCB pins.
   
  Just an FYI, but one of the reasons the Torpedo is a safe alternative for building a tube kit is the use of the PCB. 
	

	
	
		
		

		
		
	


	



   
  Anyway, I would suggest that you refer to the several excellent articles that Dsavitsk authored on the L'esspresivo - that's what forms the basis of the Torpedo design with its PCB:
http://www.ecp.cc/less-pressivo.html
http://www.ecp.cc/less-pressivo-build.html
http://www.ecp.cc/less-pressivo-plus.html
http://www.ecp.cc/less-pressivo-plus-plus.html


----------



## tomb

BTW,
   
  Maybe Dsavitsk will post with more details, but it's not really hum (60 Hz) - or even ripple (120 Hz).  There's a small spike at around 180 Hz that has shown up for both of us in tests.  Depending on the production variance of the OT's and certain headphones, that spike runs about 2dB into audibility.  The difference is quite small and is essentially the difference with the lid on vs the lid off.  The toroid is what brought this down to about 2dB audibility.  The last thing we tried for removing it the rest of the way was shielding the OT's, but according to Dsavitsk, it made no difference.
   
  Meanwhile, I have sold several of the short kits with the old PT while we were fooling aorund with the toroid.  I have had no complaints and one individual is even selling them in "built" form.  The last PT version I built was modified with the addition of a choke.  I would highly recommend the choke on the non-toroid version.  It may just be the choke adds extra metal inside the case and that "blocks" the interference, but the existing version is definitely quieter with a choke.  Also, I put in some cheap Solens for the heck of it and amazingly, they sound every bit as good as the Clarity caps.  I think that's more an indication that Dsvatisk's design is not as susceptible to quality cap changes, than any sort of luck with the Solens.  Bottom line, I could tell no difference.
   
  I have been listening to the non-toroid version almost exclusively for the last week or two.  With my pupDAC and Grados or Sennheisers, it sounds wonderful.  You practically have to train yourself to hear the "ripple."  Even then, it seems to have no effect on the music.


----------



## cubeasic

Thanks for your reply, tomb.
   
  Ok, I figured, that it would be too much to ask, selling the transformers separately. Of course I would be willing to buy the hole short kit as well (with the PCB and the nice case lying around useless afterwards), but in your post it sounds that the print-transformers could not be used properly in a point-to point setup.
   
  I have to admit, I have never done a point to point setup, and I believe you that it could be difficult with the wrong parts. So, thank you for this information.
  On the other hand, I have built anything solid state, from source to poweramp, so I am not afraid of high voltages.
   
  Of course, I have already been reading into the mentioned links on the l´espressivo, but the choice of transformers seemed critical (and expensive, depending on the tranformer) for the use with grado headphones, so I thought I might just ask for the "stock transformer package" and maybe get a hint or two on the way.
   
  I understand that, if a "non-stock" version of the torpedo is the aim, maybe this is the wrong tread to post, so I will do some reasearch of my own and maybe find help in another thread or forum.
  BTW, it is not just about the (maybe noexisting) "hum" , but I really want to make a "diy wrapping" of the hole package.
   
  Thanks,
  Flo


----------



## tomb

I understand.  However, the whole point of the Torpedo was to produce a true transformer-coupled, high-voltage tube amp that was based completely on a single PCB.  Such an animal still does not exist, even now - except for the Torpedo.
   
  The links I gave you are Dsavitsk's experience in designing the predecessors to the Torpedo - which are all point-to-point.


----------



## catfish

Why do we need a PCB for this.  The design for Grados is incredible,  but if one can't p-p such a simple amp they probably shouldn't be messing with HV in the first place ?
   
  If you really want to do the DIY community a favor,  get a group buy or somehow make permalloy headphone size parafeed output transformers available.   Thats what we need,  thats the hole in the market.  Not a PCB.  Most would pay triple what E-Print would charge to wind them,  just need to order enough lamination and find the right wind.


----------



## tomb

troll ...


----------



## vixr

Quote: 





catfish said:


> If you really want to do the DIY community a favor,  get a group buy or somehow make permalloy headphone size parafeed output transformers available.   Thats what we need...


 
  c'mon tomb... this is what we _really_ need.


----------



## tomb

Quote: 





vixr said:


> c'mon tomb... this is what we _really_ need.


 
  I hope you're kidding, vixr.


----------



## vixr

Quote: 





tomb said:


> I hope you're kidding, vixr.


 
  I am kidding...sometimes I cant resist feeding the trolls.


----------



## KimLaroux

Quote: 





vixr said:


> I am kidding...sometimes I cant resist feeding the trolls.


----------



## nikongod

I'm not really sure that he is trolling.*
   
  It is worth noting that if its not on a PCB basically nobody on head-fi builds it**, so whats the point in starting a thread? Doug has many very cool designs on his site, nobody builds them, but there they are... 
   
   
  * Whats wrong with the other "super-aloy" transformers that are available from Sowter, magnequest, Lundahl, etc? There are quite a few realllly nice transformers available already. 
   
  **the MHSS is an exception.


----------



## tomb

Quote: 





nikongod said:


> I'm not really sure that he is trolling.*
> 
> It is worth noting that if its not on a PCB basically nobody on head-fi builds it**, so whats the point in starting a thread? Doug has many very cool designs on his site, nobody builds them, but there they are...
> 
> ...


 
  I agree with your assessment on PCB's, but that's the arena here and one that I'm in, too.  I also agree with your point that Doug has many very cool designs on his site.  Seriously, the intent was to bring high-voltage, tube amp quality sound to a PCB that was fairly idiot-proof and inexpensive to the masses.  Heck, it's the first high-voltage amp I've built and now I've built several of them.  I'm not sure I'm ready to try a point-to-point, even now.  It was one of the reasons I talked him into designing it - because I wanted to build his L'esspresivo without fear. 
	

	
	
		
		

		
		
	


	



   
  You'll have to ask him about the transformers, but I suspect all the other ones you mentioned are too expensive for the idea involved, here.  He is also busy at work with a "Super-Torpedo," but it's not going to be anywhere near as inexpensive or use $2 tubes.


----------



## UKToecutter

Tom,
   
  For clarity;
  If I order a kit now, which version do I get?
  The topedo website and the Beezar website make no mention of the toroid.
  Andy


----------



## tomb

Quote: 





uktoecutter said:


> Tom,
> 
> For clarity;
> If I order a kit now, which version do I get?
> ...


 
  That's true.  It's not available yet and to tell the truth, the toroid has little or no effect in the standard Torpedo.  In fact, it may be worse.  It also costs significantly more.  If Dsavitsk is able to solve the toroid's problem with the mfr, then we may offer it as standard with the Super-Torpedo.  (I think Dsavitsk hates that name, but I don't have a better one at the moment.)  That's assuming it becomes an improvement.  There are some other mods that he's discovered that may actually address the hum in the standard Torpedo.  I haven't tested them yet, but I've actually been running a standard Torpedo that's as quiet as the Super-Torpedo and is quite acceptable as my primary amp with Grados.  It uses the 5844 tubes and includes a choke, but there are no other mods beyond that.
   
  Dsavitsk currently has three different versions of the Torpedo, along with several different transformers, and is still busy running every test in the book.  He's discovered some interesting things, but we'll have to wait until he's ready to discuss them.


----------



## UKToecutter

Tom,
   
  Thanks for the confirmation.
  I've placed my order.
  I look forward to hearing about the latest 'discoverys' and hope they'll be published before I build.
   
  Thanks
   
  Andy


----------



## UKToecutter

TomB
   
  Everything arrived this morning.
  I have to say, your packing is impeccable.
  Many Thanks
   
  Now to sort out my Mouser order..........


----------



## tomb

Quote: 





uktoecutter said:


> TomB
> 
> Everything arrived this morning.
> I have to say, your packing is impeccable.
> ...


 
  Many thanks on the compliment!  Good luck on your build!
   
  P.S. If you're still ordering - be sure to get the choke, if you can.  It will be quieter that way.


----------



## UKToecutter

Tom,
   
  Choke on order from Mouser.
   
  BTW, the 1N5820 specified in the BOM is no longer available at Mouser.
  I have sustituted [size=9pt]863-1N5820G[/size] which seems to be the identical spec.
   
  Andy


----------



## scootsit

Quote: 





tomb said:


> Super-Torpedo.  (I think Dsavitsk hates that name, but I don't have a better one at the moment.)


 
  Missile?
  Put some fins on it...


----------



## dsavitsk

I pushed for _Salsiccia_, but was overruled.


The slight mod I proposed to Tom is that we can beef up the CCS impedance a little. The CCS forms a voltage divider with the rp of the tube. The higher the CCS impedance and the lower the rp, the less power supply noise gets through. CCS impedance is basically

Hfe1 * Hfe2 * Re (Re is the current setting resistor (R4 and R5))

which is roughly 1M here. Good, not great. Actually, not really even that good. It is only about 50dB noise reduction. However, if we change out the top LED (D12 and D14) for say a 6.8V zener, then for the same current we need a 400R resistor [the current is (Zener voltage - 0.6) / Re], which bumps the impedance up to 6M which is 6x better (about 66dB of PSRR). The downside is that we have to drop an additional 5V across the CCS, which is not a big deal here. 

With a 15V zener and a 1K resistor we get 74dB. However, the 15v Zener happens to be quite noisy, and will and up doing more harm than good. 6.8v seems to be a good quiet spot.

This is not a complete fix -- there is some noise that is PS noise getting through CCS that this will mitigate. However, the bulk of the noise seems to be noise from the transformer getting into the case and then getting into the circuit. Not sure how, but that's what is going on. 

Also note that the Zener points the opposite direction of the LED, schematically speaking, with the cathode toward the positive marker on the PCB. If you put it in backwards you'll get very little current through the tube.


----------



## UKToecutter

Hey chaps
   
  I'm having a problem with my build.
   
  Only one channel working.
   
  On switch on, D10, D11 and D13 light up immediately.  D14 and D15 light up after about 10 seconds.  D12 never lights up.
   
  Any ideas?


----------



## tomb

Quote: 





uktoecutter said:


> Hey chaps
> 
> I'm having a problem with my build.
> 
> ...


 
  Did you solder the proper jumper(s) at A-B-C-D?  One of mine did something similar when I forgot to solder the power transformer jumpers.
   
  Be careful.  What's your house voltage in the UK?  If 120V, then solder a jumper from A-B and then another jumper from C-D.  If 220V, then solder a single jumper from B-C, that's all.
   
  Assuming that's the issue, of course ...


----------



## UKToecutter

Tom
  Thanks for the response but that's not the issue.
  Jumper is B-C 220V.
   
  As I said, one channel works fine.
   
  I just checked without any tubes in and D13 still lights up and it shouldn't without a tube.
  I'm guessing Q3 or Q5


----------



## tomb

Quote: 





uktoecutter said:


> Tom
> Thanks for the response but that's not the issue.
> Jumper is B-C 220V.
> 
> ...


 
  No offense, but your previous post included D11 - that's in the other channel from the other two.
   
  There are some versions of MJE's that have different pinouts, but seems that would've affected both channels.  Let's see what Dsavitsk says.
   
  Meanwhile, some pics might help.


----------



## UKToecutter

Tom
  I hope I didn't come across as 'crabby' 
  Fault seems to have changed.
  Neither D12 or D13 light up now.
   
  Happy to wait for Dsavitsk


----------



## dsavitsk

Have you tried swapping the tubes from left to right? It could be a bad tube. Could also be an LED in the wrong way. Otherwise, I'd check the solder joints, look for shorts, etc. If none of that helps, then look to the transistors.


----------



## tomb

I like the LED idea.  I've done that a couple of times, myself.  Hopefully, it should be easy to check if the LEDs have flanges.
   
  I didn't think you were crabby. Let us know.


----------



## UKToecutter

SHE LIVES!!!!
   
  Swapped the MJE350 and 2N5087.
   
  BIG GRIN.
   
  Tube rolling any time now.


----------



## tomb

Great news!!  It sounds like you were right all along!  What do you think - too much heat during soldering, maybe, or just defective transistors?


----------



## UKToecutter

Who knows?
   
  One thing I do know is that I don't have any hum, buzz or noise (I grounded all my heatsinks but no other changes).
   
  I'm using Mullard CV4031's and they sound absolutely 'lush'


----------



## tomb

Quote: 





uktoecutter said:


> Who knows?
> 
> One thing I do know is that I don't have any hum, buzz or noise (I grounded all my heatsinks but no other changes).
> 
> I'm using Mullard CV4031's and they sound absolutely 'lush'


 
  Outstanding!


----------



## RollE2k

Quote: 





> Originally Posted by *dsavitsk* /img/forum/go_quote.gif
> 
> This is not a complete fix -- there is some noise that is PS noise getting through CCS that this will mitigate. However, the bulk of the noise seems to be noise from the transformer getting into the case and then getting into the circuit. Not sure how, but that's what is going on.


 
   
   
  I'm looking into ordering this kit, since this is exactly what i have been thinking about building myself - but i have a few questions. I have not read the whole thread so this may been answered before, but anyway...
 First - if you install a small choke, doesn't this help lowering the noise issue below?
 Secondly, with the stock tubes and the amp at either low or high what is the gain of the amp (i assume it is negative?), or rather what is the step-down values of the transformer with low and high gain?
 Also, have anybody tried moving the tubes up at the top of the case and thus maybe getting rid of the noise?


----------



## tomb

Quote: 





rolle2k said:


> I'm looking into ordering this kit, since this is exactly what i have been thinking about building myself - but i have a few questions. I have not read the whole thread so this may been answered before, but anyway...
> First - if you install a small choke, doesn't this help lowering the noise issue below?
> Secondly, with the stock tubes and the amp at either low or high what is the gain of the amp (i assume it is negative?), or rather what is the step-down values of the transformer with low and high gain?
> Also, have anybody tried moving the tubes up at the top of the case and thus maybe getting rid of the noise?


 
  1. Yes, the choke is recommended.  It contributes to lowering hum (it's actually a 180Hz anomaly).
  2. Dsavitsk will have to answer this directly.  I can tell you that at Low-Z, Grados are perfect medium-listening levels at 12 o'clock (HF-2, HF-1, SR-225's).  Sennheisers (HD600, HD580) are the same at High-Z - 12 o'clock on the volume knob.
  3. Yes - see earlier in the thread.
HiGHFLYiN9 built a very-nice looking steam-punk finished Torpedo with the tubes outside of the case.  The tubes are not causing the noise.  It's the PT reflecting off of the case.
   
  Noise: As stated, it's been found to be a 180Hz anomaly from the PT.  With the choke, chances are that you will never hear it with some headphones.  With others, it may be barely detectable.  Besides using the choke and trying Dsavitsk's zener diode fix (I haven't tried it just yet), reducing current overall in the amp also quietens it.  For instance, the 5844 tubes use about 1/2 the heater current.  They are much quieter.  Really, though, the choke does the most IMHO (unless the Zener works even better).


----------



## RollE2k

Good to hear, i have bought a pair of used ATH-w1000x which are 42ohms that i will need a new headphone-amp for soon, so this looks as a nice project!
 Depending on the step-down value of the transformers i was thinking about trying top-mounted tubes 6n1p or ECC88's. since i have some nos of these.
 Will check the pictures and waiting answer regarding the step-down value!


----------



## dsavitsk

Voltage gain into 32 Ohms is ~2x. Into 300 Ohms it is about 6x.


----------



## RollE2k

Quote: 





			
				dsavitsk said:
			
		

> Voltage gain into 32 Ohms is ~2x. Into 300 Ohms it is about 6x.


 

 Great to know, then there is probably possibility to put lower-gain tubes there also. Do you have exact step-down ratio or is that a secret? 
 Also when running tubes without common cathode, it is not possible to set current separately for each tube half right (i'm thinking to set more exact current between both triode-halves) it doesn't look like that from the schematics at least.


----------



## yuujin

hi guys, i know the bijou is different in design, but i would like to ask if anyone has listened to both of them?


----------



## dsavitsk

rolle2k said:


> Great to know, then there is probably possibility to put lower-gain tubes there also. Do you have exact step-down ratio or is that a secret?
> 
> Also when running tubes without common cathode, it is not possible to set current separately for each tube half right (i'm thinking to set more exact current between both triode-halves) it doesn't look like that from the schematics at least.




I am not aware of any lower mu tubes that will fit the board.

mu is 38. The transformer is 10K:32 or 10K:300. That means that the turns (step down) ratio is ~17.5 for the low Z setting and 5.8 for high. This gets you slightly higher gain than I suggested above, but if you account for copper and core losses, etc, it is about 2 and 6.

The cathodes are tied internally, so there is no way on this amp to set current independently. I suppose you could in theory use resistors on each plate to try to equalize things, but there is no reason to do so.


----------



## RollE2k

Quote: 





dsavitsk said:


> I am not aware of any lower mu tubes that will fit the board.
> mu is 38. The transformer is 10K:32 or 10K:300. That means that the turns (step down) ratio is ~17.5 for the low Z setting and 5.8 for high. This gets you slightly higher gain than I suggested above, but if you account for copper and core losses, etc, it is about 2 and 6.
> The cathodes are tied internally, so there is no way on this amp to set current independently. I suppose you could in theory use resistors on each plate to try to equalize things, but there is no reason to do so.


 

 I was thinking about maybe mount the tubes at the top of the case, so 9-pin socket would fit then. But still, its probably better getting matched/balanced tubes then.
  Last questions then; 
 Approx what current are the tubes running, and how much can you "up" the default CCS?
 And one thing i don't get about parafeed - when running a transformer as a anode load (like normal SET) the transformer does simply emulate a impedance loading for the tube, and its really important to match with right step-down ratio. But when running parafeed isn't that as critical - that means the more step-down the better (at least as long as the gain is enough). Am i right about this?
 If that above is true then lowering plate resistance (with another tube for example) would mean that you could easily drive lower impedance headphones.


----------



## dsavitsk

If you use a different tube with the socket mounted off board, then yes you could match the current. But, I really think it is unnecessary.

The tubes run at ~15mA. I would not increase it too much as we are running the power transformer at close to the limit. This is particularly true w/r/t/ heater current, so don't use a tube that will increase that.

In parafeed, the transformer is in parallel with the CCS and presents the "real" load. It is incorrect (though repeated all over the web) that there is an infinite load on the tube.

Driving headphones is not like driving speakers. You do not need a super low Z or a high damping factor. The back EMF is much lower, the load lines are nearly flat, and there are generally no crossovers to worry about. So, a super low output impedance is just not that important. This amp will drive just about anything you throw at it.

This might help with your other questions, and it explains the parallel load issue in more detail: http://diy.ecpaudio.com/p/parafeed-tutorial.html


----------



## tomb

Just curious, but would anyone be interested in bronze-brown (root beer?) anodized cases or just black?  I'm talking about something similar to the Torpedo website color scheme.


----------



## Chet_Summers

If you do black I'd have to break down and order a short kit.


----------



## scootsit

tomb said:


> Just curious, but would anyone be interested in bronze-brown (root beer?) anodized cases or just black?  I'm talking about something similar to the Torpedo website color scheme.




My opinion shouldn't really count, because I'm way too happy with my Millett to be wanting. BUT, I'll offer it anyway. 

I think you should go for a cream yellow like the old heathkits. Something super vintage looking. Maybe if it had the hammered texture to the finish with the brown, which was not unheard of on vintage amps.


----------



## KimLaroux

Quote: 





highflyin9 said:


> Finished up yesterday:
> 
> 
> 
> [...]


 
   
  I think this design should be made the final kit. It's simply outstanding. The color scheme, the textures, the logo plate, the hardware... it fits perfectly. It has more charm than the plain aluminum kit. The plain aluminum enclosure reminds me of industrial power supplies. =P Not something that would blend in an hi-fi setup, anyways.
   
  Steampunk winz. The only thing I would modify on this build is pull the tubes about 1 cm lower, so that the sockets don't show.


----------



## tomb

Hmm ... I can't do all of that, even though I agree.  What if the case were black and the endplates anodized bronze in the pic?


----------



## UKToecutter

I wonder if someone can assist me with some strange test results I'm getting.
  I've been testing the tubes that Tom supplied me with.
  6J6's and 5964's give me results I would expect.  The 5844's however give me some very strange results.
   
  As an example, here is the test results of a 5964;
   
   

 Test Results   [size=medium]Tube[/size]   [size=medium]Method[/size]     [size=medium]5964[/size]   [size=medium]Fixed Bias[/size]           *Item * *[size=medium]Unit[/size]* *[size=medium]Spec [/size]* *[size=medium]Result 1 [/size]* *[size=medium]Result 2[/size]* Plate Volts                        [size=medium] Ep vdc[/size] [size=medium]100[/size] [size=medium]100[/size] [size=medium]100[/size] DC Plate Current         [size=medium] Ip mAdc[/size] [size=medium]9.5[/size] [size=medium]7[/size] [size=medium]6.8[/size] AC Plate Current         [size=medium] Ip mAac[/size] [size=medium]~[/size] [size=medium]0.531[/size] [size=medium]0.485[/size] Screen Volts                     [size=medium]G2 vdc[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] Screen Current  [size=medium]IG2 mA[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] Bias Volts  [size=medium]G1 vdc[/size] [size=medium]1[/size] [size=medium]1[/size] [size=medium]1[/size] Test Signal Volts  [size=medium]RMS[/size] [size=medium]~[/size] [size=medium]0.1[/size] [size=medium]0.1[/size] Mutual Conductance  [size=medium]uMhos[/size] [size=medium]6000[/size] [size=medium]5310[/size] [size=medium]4850[/size] Grid #1 Leakage  [size=medium]uA[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0.01[/size] H/K Leakage  [size=medium]mA[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] Plate Resistance  [size=medium]RP ohms[/size] [size=medium]~[/size] [size=medium]5.5K[/size] [size=medium]7.1K[/size] Tube Gain  [size=medium]Mu[/size] [size=medium]~[/size] [size=medium]29.2[/size] [size=medium]34.4[/size] Heater  [size=medium]eF vdc[/size] [size=medium]6.3[/size] [size=medium]6.3[/size] [size=medium]6.3[/size] Heater Run Time  [size=medium]Sec[/size]   [size=medium]65[/size] [size=medium]86[/size]
   
  So all looks reasonable.
   
  I pulled the 5844 datasheet and the typical operating parameters are Ep vdc 100V and Ip mAdc 4.8mA with uMhos 3700
  I set my tester to these characteristics and ran the test.
  Results were;
   
   

 Test Results   [size=medium]Tube[/size]   [size=medium]Method[/size]     [size=medium]5844[/size]   [size=medium]Fixed Bias[/size]           *Item * *[size=medium]Unit[/size]* *[size=medium]Spec [/size]* *[size=medium]Result 1 [/size]* *[size=medium]Result 2[/size]* Plate Volts                        [size=medium] Ep vdc[/size] [size=medium]100[/size] [size=medium]100[/size] [size=medium]100[/size] DC Plate Current         [size=medium] Ip mAdc[/size] [size=medium]4.8[/size] [size=medium]10.1[/size] [size=medium]10.1[/size] AC Plate Current         [size=medium] Ip mAac[/size] [size=medium]~[/size] [size=medium]0.6[/size] [size=medium]0.61[/size] Screen Volts                     [size=medium]G2 vdc[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] Screen Current  [size=medium]IG2 mA[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] Bias Volts  [size=medium]G1 vdc[/size] [size=medium]1[/size] [size=medium]1[/size] [size=medium]1[/size] Test Signal Volts  [size=medium]RMS[/size] [size=medium]~[/size] [size=medium]0.1[/size] [size=medium]0.1[/size] Mutual Conductance  [size=medium]uMhos[/size] [size=medium]3700[/size] [size=medium]6000[/size] [size=medium]6100[/size] Grid #1 Leakage  [size=medium]uA[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] H/K Leakage  [size=medium]mA[/size] [size=medium]0[/size] [size=medium]0[/size] [size=medium]0[/size] Plate Resistance  [size=medium]RP ohms[/size] [size=medium]~[/size] [size=medium]10.3K[/size] [size=medium]11.1K[/size] Tube Gain  [size=medium]Mu[/size] [size=medium]~[/size] [size=medium]61.8[/size] [size=medium]67.7[/size] Heater  [size=medium]eF vdc[/size] [size=medium]6.3[/size] [size=medium]6.3[/size] [size=medium]6.3[/size] Heater Run Time  [size=medium]Sec[/size]   [size=medium]215[/size] [size=medium]236[/size]
   
  It looks to me as thought the Mutual Conductance and DC Plate Current are wrong.
   
  Have I got a rougue 5844 datasheet??
   
  Any assistance appreciated.
   
  Andy


----------



## tomb

I'll study your figures more when I get some time, but just an FYI - the Torpedo runs at 200V on the plates, whereas the maximum plate voltage on 5844's is 175V.  So, the 5844's are being over-driven in the Torpedo.


----------



## UKToecutter

Strangely enough the GE datasheet does specify a maximum anode voltage of 200V


----------



## dsavitsk

It looks to me like they put 6J6 guts in a bottle and labeled it a 5844.


----------



## tomb

Was it one of mine or someone elses?  The Beezar 5844's are all GE 5-star's, AFAIK.


----------



## UKToecutter

Tom
   
  Yours.
  They all work great, I'm just confused about the tester results.
  If I test them as a 6J6 the results make more sense but don't really match the datasheet.
   
  Tres wierd......


----------



## UKToecutter

Tried some Russian 6N15P.
  They sound real good. Perhaps a little 'slower' than the CV4031's but I'll give them a little time to burn in.


----------



## tomb

Quote: 





dsavitsk said:


> I pushed for _Salsiccia_, but was overruled.
> The slight mod I proposed to Tom is that we can beef up the CCS impedance a little. The CCS forms a voltage divider with the rp of the tube. The higher the CCS impedance and the lower the rp, the less power supply noise gets through. CCS impedance is basically
> Hfe1 * Hfe2 * Re (Re is the current setting resistor (R4 and R5))
> which is roughly 1M here. Good, not great. Actually, not really even that good. It is only about 50dB noise reduction. However, if we change out the top LED (D12 and D14) for say a 6.8V zener, then for the same current we need a 400R resistor [the current is (Zener voltage - 0.6) / Re], which bumps the impedance up to 6M which is 6x better (about 66dB of PSRR). The downside is that we have to drop an additional 5V across the CCS, which is not a big deal here.
> ...


 
  I've tried this mod a couple of times today - back and forth between the Zener, the 2nd LED, and the resistor (R4, R5) on each channel's CCS.  It seems to cut the noise by 1/2.  So, I would highly recommend it.  I will document it on the Torpedo website when I get a chance.
   
  To be specific, I used 6.8V Zeners with RN60 402R resistors.
   
  Meanwhile, I"m going to start selling _full_ kits in the next day or so ... they will include the Zener mod to the CCS.


----------



## RollE2k

i know you said that the transformer is pretty much used full out, but i'm thinking about top-mounted tubes with 9-pin socket and wires to them from PCB. Then a choke on the PSU.
 I know heater supply is pretty much maxed with 6J6 (~450mA) tubes - but if i used say ECC88 instead, where heater is only ~300mA - than that would probably be better for the hum that some people hear.
 BUT is the main B+ able to deliver around 20-25mA/channel? or would that need a completely new transformer?


----------



## tomb

Quote: 





rolle2k said:


> i know you said that the transformer is pretty much used full out, but i'm thinking about top-mounted tubes with 9-pin socket and wires to them from PCB. Then a choke on the PSU.
> I know heater supply is pretty much maxed with 6J6 (~450mA) tubes - but if i used say ECC88 instead, where heater is only ~300mA - than that would probably be better for the hum that some people hear.
> BUT is the main B+ able to deliver around 20-25mA/channel? or would that need a completely new transformer?


 
  I can't answer your specific question, but the Zener diode mod plus the choke has removed the hum for all but the most efficient headphones.  More than that, it has changed the character of the amp, IMHO.  _I no longer care if I can hear some barely imperceptable hum_ - the amp is significantly more detailed, bass is tighter and deeper, etc. - IOW, all the good things one might expect from a much cleaner power supply are present.
   
  Plus, Dsavitsk says we can remove the other CCS LED and replace it with another diode for even greater gains in S/N and PSRR.  I haven't tried that yet, but am so confident that this amp's sound is where we want it that I ordered another 500 tubes for stock at Beezar.  I'm going to order new cases and transformers soon, too.  Full kits will be available soon and I'm thinking seriously of offering built versions.
   
  Combined with the pupDAC, whose frequency response greatly mimics the Torpedo (a very slight ~1dB drop off at 20KHZ), it's the best Grado sound I've had in my house.  I have the HF-1, HF-2, and a pair of SR-220's.  There's no tizziness, no "hot-enough-to-burn-your-ear" effects.  At the same time, bass is deep and punchy and cymbal crashes are smooth and distinct.  I find myself listening to the HF-1's because the highs are a bit more extended and clear than on the HF-2's.  (Some very gracious DIY Head-Fi members gave me the HF-1's for Christmas a few years ago.)  My HD600's with Cardas cable are almost identical sounding on the High-Z switch.  Which is why I've always said a Cardas cable on the HD600 turns it into a Grado with soundstage.  The HD580's, not so much, but then I've never liked the 650 cable it has (very dark).
   
  (Before you think I've gone off the deep end, I don't believe in re-cabling in most cases, but cable improvements have always worked with the 580/600/650's.
	

	
	
		
		

		
			





)


----------



## liamstrain

> (Before you think I've gone off the deep end, I don't believe in re-cabling in most cases, but cable improvements have always worked with the 580/600/650's.
> 
> 
> 
> ...


 
   
   
We'll just allow that you've accidentally fallen into the shallow end of the same pool. ​  ​ Sounds like great things happening in Torpedo land. I look forward to further developments and refinements. ​


----------



## dsavitsk

tomb said:


> Plus, Dsavitsk says we can remove the other CCS LED and replace it with another diode for even greater gains in S/N and PSRR.




Oh no, I meant that you can use 2x 6.8 zeners in series to drop 13.2V, which will require a ~840 Ohm resistor. Leave the other LED where it is.

As for the power transformer, no, it will not do 20-25mA per side. Further, I don't think there is sufficient voltage headroom for running 6922's at that high of a current with the biasing scheme we use. However, running 6922's at 15mA with the 2 sides in parallel (so 7.5mA/side) will be fine. And, as you guess, the lower heater current will probably lower the noise a little. And, as Tom implied, the noise really is low. I have heard plenty of DIY and commercial amps that are noisier.


----------



## tomb

Quote: 





dsavitsk said:


> Oh no, I meant that you can use 2x 6.8 zeners in series to drop 13.2V, which will require a ~840 Ohm resistor. Leave the other LED where it is.


 
  OK - glad you clarified that!


----------



## thelostMIDrange

I see the 'short kit'
http://beezar.com/catalog/product_info.php?cPath=42&products_id=142
   
  but it was mentioned a full kit was coming>  full, meaning I won't have to source all the remaining parts from mouser et al? Or am I misunderstanding the word 'full'......This looks like a sweet winter project for my grado's !  Pretty transparent and untubey sounding?


----------



## tomb

Quote: 





thelostmidrange said:


> I see the 'short kit'
> http://beezar.com/catalog/product_info.php?cPath=42&products_id=142
> 
> but it was mentioned a full kit was coming>  full, meaning I won't have to source all the remaining parts from mouser et al? Or am I misunderstanding the word 'full'......This looks like a sweet winter project for my grado's !  Pretty transparent and untubey sounding?


 
  No, you didn't misunderstand.  I'm just behind ... as usual.  It'll show up this weekend, for sure.


----------



## thelostMIDrange

sweet. thanks for developing this unique beast. reading from the site, there is mention of some attention needed for soldering on this type of board and possibly heating from both sides. Would a standard radio shack 15W iron and 60/40 .032" light duty solder be sufficient to put this together.....


----------



## tomb

Quote: 





thelostmidrange said:


> sweet. thanks for developing this unique beast. reading from the site, there is mention of some attention needed for soldering on this type of board and possibly heating from both sides. Would a standard radio shack 15W iron and 60/40 .032" light duty solder be sufficient to put this together.....


 
  The 15W soldering iron might be OK, but Radio Shack stuff is not always the best.
	

	
	
		
		

		
		
	


	




  I always recommend 63/37 eutectic solder.  Radio Shack sells it:
http://www.radioshack.com/product/index.jsp?productId=2062718&filterName=Type&filterValue=Solder#
  I'm not sure what diameter that is, but it's 63/37, which is what's important.  Anything from 0.025 to 0.035 is probably OK.  I use 0.025, but then I use it for SMD soldering, too, and that's about as small as you get solder without it breaking on you all the time.
   
  Just an FYI, but eutectic solder (63/37) is the single concentration mix where the solder mixture all has the same melting point - and also the lowest possible melting point of the alloy.  So the joint is automatically the best that can be made - all shiny with good contact, assuming you use the right heat:
http://en.wikipedia.org/wiki/Eutectic
   
  One might ask, "Why make any solder that's not eutectic?"  _"The pasty state of a non-eutectic solder can be exploited in plumbing as it allows molding of the solder during cooling, e.g. for ensuring watertight joint of pipes, resulting in a so-called 'wiped joint'." _
  We're not interested in any of that with electronics, so eutectic is best.


----------



## thelostMIDrange

thanks, found the info as well here and looks like something I could put together as you guys make it easy with all the step by step....... Will keep and eye out for the Full kit !
http://www.diyforums.org/Torpedo/TORPEDOoverview.php


----------



## thelostMIDrange

can anyone comment on the transparency and untubey'ness of this amp please before I take the plunge. I've taken the tube plunge a few times before with a few low end headphone amps and got a little too soaked with tube'y sound....I like the idea of using OT's though and would like to try this. just looking for a few words of encouragement first.....


----------



## UKToecutter

Don't hesitate.
  It's a great amp.
  You can have great fun tube rolling as well


----------



## tomb

Did someone say tube rolling?
   
  6J6, 6J6-A, 6J6S, 6J6-W, 6J6-WA, 1216, 5844, 5964, 6030, 6045, 6099, 6101, 6535, 6927, 6CC31, 6MNN3, CK6101, CV5046, CV8160, CV8231, CV858, ECC91, M8081, T2M05, CV2843, CV4031, _6N15P_. 
	

	
	
		
		

		
			




  (edited)


----------



## UKToecutter

Don't forget 6N15P.
  Nice cheap Russian tubes......


----------



## dsavitsk

thelostmidrange said:


> can anyone comment on the transparency and untubey'ness of this amp please before I take the plunge.




When people talk about tubey ness, this is usually due to recessed highs and lows, high distortion, and electrolytic caps in the signal path. The CCS loaded parafeed, the lack of DC in the output transformers, and the BJT bias elements in this amp eliminate all of that.


----------



## mundo

Kinda off topic and perhaps a bit silly to ask. I'm currently building my Torpedo, and the Cat came and decided to jump on my desk. In the process he knocked the Auricaps I was going to use for C11/C12 off my desk and onto the carpet. Should I be worried about any damage? Externally they look fine, and only fell about 3 ft. I'd just hate to get them soldered up and have them be a problem.


----------



## liamstrain

Not much to go wrong inside a standard capacitor (electrolytic or pp film cap) that wouldn't be visible from the outside, as far as I can tell.


----------



## mundo

That was my thinking, but then I seemed to remember something a prof said about not dropping caps in a electrical circuits lab years ago. Perhaps I just misremembered what was said in that lab.


----------



## jdkJake

Those are film caps. They will be perfectly fine.

Unless you stepped on them while they were on the floor. 

...or the cat chewed on them a bit.


----------



## mundo

No, the cat didn't get the chance to bite them. Just gave them a quick wack off the desk.


----------



## catfish

Any chance of a permalloy OPT upgrade in the future for us ?


----------



## tomb

Quote: 





catfish said:


> Any chance of a permalloy OPT upgrade in the future for us ?


 
  No, but I am going to change the listing on Beezar: the cases will be BLACK anodized within a week, with laser-etching to follow shortly after that.


----------



## tomb

Kits and Short Kits for the Torpedo will be out-of-stock for a few days while the anodizing/laser-etching is in work.
   
  I have updated the Torpedo BOM on the Torpedo website to reflect the latest changes and the Zener diode tweak for D12, D14, and R4, R5.


----------



## dsavitsk

catfish said:


> Any chance of a permalloy OPT upgrade in the future for us ?




I'll disagree with Tom -- yes, there is a chance, but it will not be cheap, it will involve a group buy type of arrangement (it won't likely be something we stock), and it will not happen until the final bit of noise is eliminated. In the meantime, I know of a nice amp that has a similar topology and uses Permalloy outputs.


----------



## tomb




----------



## funch

Nice! Very nice.


----------



## OJNeg

I am _very_ tempted by this kit right now.


----------



## DingoSmuggler

looks so much better in black
nice work tomb

i know its unlikely, but is there a chance of buying just a set of black endplates?


----------



## Nisbeth

Quote: 





ojneg said:


> I am _very_ tempted by this kit right now.


 
  +10 
	

	
	
		
		

		
			




   
  /U.


----------



## tomb

Quote: 





dingosmuggler said:


> looks so much better in black
> nice work tomb
> 
> i know its unlikely, but is there a chance of buying just a set of black endplates?


 
  Not right now.  If I sell the ones in stock now and then order a brand new production run, that might be possible.  I can order some extra endplates at that time.


----------



## DingoSmuggler

Quote: 





tomb said:


> Not right now.  If I sell the ones in stock now and then order a brand new production run, that might be possible.  I can order some extra endplates at that time.


 
  cheers


----------



## tomb

I've included a detail for the Zener Diode Tweak on the Torpedo website under "Tweaks:"




 This is now standard on the BOM and in the kits, as is the Hammond choke instead of R2.  Note that as Dsavitsk has mentioned, the Zener Tweak also requires R4 and R5 to be ~400R.


----------



## dBel84

I don't browse these forums enough , I miss seeing all this really cool stuff. Well done Tom and Doug - the amp looks great ..dB


----------



## yuujin

would the torpedo drive a lcd-2 properly?


----------



## scootsit

Tomb and Dsavitsk could answer better.
   
  BUT it should drive the LCDs really well!


----------



## Pars

I'm not sure, but it didn't seem like my brother's beta Torpedo drove them very well.


----------



## tomb

Quote: 





pars said:


> I'm not sure, but it didn't seem like my brother's beta Torpedo drove them very well.


 
  Yeah, I saw the question and didn't want to answer it directly having no LCD-2's myself, but since you did ... 
	

	
	
		
		

		
		
	


	




  The current Torpedo with a choke and Zener mod is much improved, otherwise I wouldn't have thought it worth the huge investment to anodize, laser-etch, and start offering _full_ kits.  Paired with my pupDAC and HF-2's (sometimes HF-1's), it's all I listen to.
   
  That said, I agree that perhaps the circuit may not be ideal for orthos.


----------



## scootsit

My mistake, I figured the huge current of the torpedo would be great for their low impedance and high demand.
   
  Sorry! I really need to stick to things I know!


----------



## tomb

Quote: 





scootsit said:


> My mistake, I figured the huge current of the torpedo would be great for their low impedance and high demand.
> 
> Sorry! I really need to stick to things I know!


 
  Well, I'm basing that on listening to my K701's.  They come about as close to ortho power requirements as any pair of dynamic phones could.  I haven't listened with the Zener mod, though - maybe that changed things.  I'll try tonight and let you all know. 
	

	
	
		
		

		
		
	


	



   
  The CanLanta Meet in May should answer a lot of this, too, but May is still a long time away.


----------



## Pars

My brother's amp does handle his T50RPs just fine, as well as the Fischer Audio FA2? or 3? Can't remember which ones he has. As well as AKG K501s.
   
  That said, this version may do better, sorry haven't been paying attention to what you and Doug have done with it. It's a nice amp!


----------



## tomb

OK, as I listen to Joni Mitchell's Blue with K701's, the Torpedo and pupDAC, I can confirm that it's performing entirely differently than it used to on a K701.  Punch is there, pretty good bass (which is saying something with K701's).  Of course, detail and especially midrange is outstanding.  I still prefer the way my HF-2's and HF-1's render cymbal crashes, but this is pretty nice. 
	

	
	
		
		

		
			





  (The damn center bump gets to me in about 15 minutes, though! 
	

	
	
		
		

		
		
	


	




)  There is no hum whatsoever detectable with the K701's.  I think that may have always been true, but things are more dynamic, now - as if the amp is able to "drive" the headphones instead of coasting. 
   
  There may be something about impedance, too.  It seems the K701, Audeze, and even KSC-75's all fall into the 50-70 ohm range.  I have constant trouble deciding which way to throw the Z switch - it almost depends on the music selection.  Some things sound lots better on High Z but perhaps overwhelming with mids.  Other things sound a bit dead and recessed on low-Z.  One might think that since 50-70 ohms is closer to 32 ohms than 300 ohms (High Z switch), you would set the switch on Low Z.  That kind of ratio may be misleading, though, and even slight amounts above 32 ohms may mean you need to set the switch on High-Z.
   
  Well, enough talking out of my a**.  Let's see if Dsavitsk wants to add anything.


----------



## H22

Whew, read the whole thread. I am very interested in this amp, but need to finish up other projects at the moment.
   
  I was wondering how this amp compares (sound wise) to a mini or mosfet max? ,I have built both and really, really like My Mosfet-Max, and wish i had not given the mini away as a gift.
  just wanted to know what differences there were, if any.
   
   
  joe


----------



## tomb

Quote: 





h22 said:


> Whew, read the whole thread. I am very interested in this amp, but need to finish up other projects at the moment.
> 
> I was wondering how this amp compares (sound wise) to a mini or mosfet max? ,I have built both and really, really like My Mosfet-Max, and wish i had not given the mini away as a gift.
> just wanted to know what differences there were, if any.
> ...


 
  The best way I can answer in terms of sound quality is my standard blurb: _Beezar's prices are proportional to sound quality._
   
  That said, I guess it depends on your definition of sound quality.  The MiniMAX, IMHO, assembles into one of the nicest packages around and is a great value.  The MOSFET-MAX can be built as a real power brute and has a lot of flexibility with the onboard DAC, etc.  Both can be built with dead silence.  As you've probably read in this thread, however, there may be a very slight hum with certain headphones using the Torpedo.  I think we've gotten that down to no more than a nuisance and it's completely inaudible when the signal is amplified, even with those phones that can pick it up.
   
  Basically, you may notice that the Torpedo's bass is not as strong and punchy as the hybrid amps above, but the mids and highs are to die for.  There is no lack of detail whatsoever, but at the same time - harshness simply doesn't exist with this amp.  In particular, connect any Grado to this amp and you will never experience harshness, yet the detail and transients come through - same for HD600's as well.  As for the rest of the sound quality, I believe I stated this earlier in the thread - there's an airiness imparted that seems to define a real soundstage relative to hybrid and SS amps.  Some people would say that's simply the "friendly" even-order harmonic distortion that pure tube amps seem to present.  To the extent that the Torpedo is a "real" tube amp*, maybe that's true - I don't know.
   
  What I do know is that Dsavitsk has designed a true, transformer output coupled tube amplifier all based on a PCB.  There is no wiring at all, except for a small safety ground wire from the PCB to the case and the ubiquitous ground wire for the Alps RK27 volume pot.  There is no turn-on or turn-off thump whatsoever, gain is perfect (middle of the dial or slightly less for almost every headphone I own), and low impedance phones (Grados especially!) are outstandingly driven.  (High-impedance affinity is already expected with a high-voltage tube amp).  To add to all of that, *the tubes are extremely plentiful, extremely varied, and dirt-cheap - I mean, REALLY dirt-cheap.  *If you are willing to buy in volume (several hundred), you can get them for a dollar or less!  With some of the bigger tube dealers, they may number into the tens of thousands.
   
  Anyway - hope that helps! 
	

	
	
		
		

		
		
	


	



   
   
  * Some may take issue with all the "sand" devices in the amp, but those are common in many "real" tube amps, yet perhaps unique in their implementation by Dsavitsk - CCS, rectifiers, biasing circuit.  The essence of the pure signal input-to-the-tube and transformer-coupled output is not corrupted.


----------



## H22

*Basically, you may notice that the Torpedo's bass is not as strong and punchy as the hybrid amps above, but the mids and highs are to die for. There is no lack of detail whatsoever, but at the same time - harshness simply doesn't exist with this amp.*

Thanks for the info, I find your assessment a little amusing, as I was reading it all I could think was that would be exactly how I would describe my MOSFET max to anyone who asked. The one thing I wish my MAX had a little more of is bass, I'm still playing with it but it just seems week on the low end. It's there, but it doesn't seem to have any punch to it. 
The mids and highs make up a lot of ground though. 
So to hear the torpedo is lacking even more on the low end gives me pause, but I think I will probably order one anyway as its such a cool amp.

Thanks again

Joe


----------



## tomb

Quote: 





h22 said:


> *Basically, you may notice that the Torpedo's bass is not as strong and punchy as the hybrid amps above, but the mids and highs are to die for. There is no lack of detail whatsoever, but at the same time - harshness simply doesn't exist with this amp.*
> 
> Thanks for the info, I find your assessment a little amusing, as I was reading it all I could think was that would be exactly how I would describe my MOSFET max to anyone who asked. The one thing I wish my MAX had a little more of is bass, I'm still playing with it but it just seems week on the low end. It's there, but it doesn't seem to have any punch to it.
> The mids and highs make up a lot of ground though.
> ...


 
  Well, thanks for the support about the Torpedo, but to hear you say the MOSFET-MAX "seems weak on the low end" is strangely baffling.  You must have something wrong enough to affect the bass, but not wrong enough to blow the fuse. 
	

	
	
		
		

		
		
	


	




  No offense, but there's no way a properly operating MOSFET-MAX would be weak on the low end.  Strong bass is pretty much the definition of the amp.  Maybe you forgot the output resistors and the MOSFETs are actually oscillating?  That would cause the bass to be very weak, while the highs might seem over-emphasized (but it's actually a psychological effect from oscillation).


----------



## yuujin

sweet. i might order myself a torpedo soon.


----------



## yuujin

Just a question. If I were to use 250VDC for the paraders caps. Will be enough?


----------



## dsavitsk

Just got back from vacation, so I am late on the LCD2 question. I am probably not the guy to ask as I don't like those headphones much. My guess would be that it is not going to drive them to ear shattering volume, but that for reasonable listening it should be an OK pairing.

For the parafeed caps, they will see voltages in excess of 250V, so 250VDC caps are not sufficient.


----------



## DingoSmuggler

I think it's time to order the components required for the zener mod this coming week. 
	

	
	
		
		

		
		
	


	



   
  At the same time i'm thinking about dropping the ccs current to about 12mA to see what the 5844 sound like biased more within their rated operating range. Tom/Doug, have you tried these tubes at a lower current?
  The problem will be doing 2 changes at once, then not knowing which has what effect to the sound, but i'm sure i'll think of something.


----------



## yuujin

sorry double post.


----------



## yuujin

Just built the Torpedo in 6 hours, worked the first time I powered it up.
  Initial impressions are really good. Setup as follows.
  AL88XX optical out > AMB y1 DAC > DIY Belden, Switchcraft Mini to Neutrik Profi RCAs > Torpedo with Mogami Power cable/Cryoed Oyaide IEC plug/GE 5844s > HD600/1964 Ears V6
  Slight hum with my 1964 V6s, but I guess that's to be expected.


----------



## tomb

Quote: 





yuujin said:


> Just built the Torpedo in 6 hours, worked the first time I powered it up.
> Initial impressions are really good. Setup as follows.
> AL88XX optical out > AMB y1 DAC > DIY Belden, Switchcraft Mini to Neutrik Profi RCAs > Torpedo with Mogami Power cable/Cryoed Oyaide IEC plug/GE 5844s > HD600/1964 Ears V6
> Slight hum with my 1964 V6s, but I guess that's to be expected.


 
  That's great news!  Glad to hear that the build went so well.  It's really pretty simple - not a lot of parts.  There's actually more hardware that you have to worry with - screws, standoffs, nuts and such - rather than any kind of soldering gymnastics.


----------



## yuujin

yeah! i realized you sent me 2 nuts short. I had to use 2 stand offs for the choke and improvise for the rest.


----------



## tomb

Quote: 





yuujin said:


> yeah! i realized you sent me 2 nuts short. I had to use 2 stand offs for the choke and improvise for the rest.


 
  Whoa - I apologize for that!  I will send you what you need - just PM me and I'll get it in the mail.


----------



## yuujin

And a reminder to all building the torpedo!
  Ground the ALPS RK27 before soldering on the OTs!
  Had a small issue with it as my screw driver wasn't small enough, and had a tough time putting on the ground wire.


----------



## tomb

Quote: 





yuujin said:


> And a reminder to all building the torpedo!
> Ground the ALPS RK27 before soldering on the OTs!
> Had a small issue with it as my screw driver wasn't small enough, and had a tough time putting on the ground wire.


 
  We used to say it was grounded through the case and the pot shaft, but with the black anodized finish, that's not possible anymore. 
	

	
	
		
		

		
			




   
  Good catch.


----------



## heku

Here is my attempt to reduce hum


 It is grounded metal box that covers output transformers. It almost completely removed hum.


----------



## UKToecutter

Heku
You could also ground the two heatsinks.
I did that on mine and I have no perceptible hum.

Andy


----------



## heku

I have grounded those heatsinks. With only heatsinks grounded there was noticeable hum.
  When I added that metal box hum was reduced to level where I have to listen closely to notice it.


----------



## KimLaroux

You shielded the output transformers but not the power transformer? Isn't most of the noise generated by the power transformer?


----------



## dsavitsk

Interesting. Yes, the noise is generated by the PT, and most of it reenters the circuit not through the OPT, but instead through the circuitry itself. Though apparently some comes in through the OPTs, too. It does seem that a combination of things leads to the best outcome -- the CCS mod, grounding the heatsinks, shielding the OPTs, possibly shielding the PT, etc.


----------



## heku

Today I made box for power transformer and now hum is gone.

  I also tried only shielding power transformer and leaving output transformers naked.
  It did reduce more hum than shielding only output transformers.
  But there was still very small amount of hum left, which disappeared when output transformers were also shielded.


----------



## tomb

Quote: 





heku said:


> Today I made box for power transformer and now hum is gone.
> 
> I also tried only shielding power transformer and leaving output transformers naked.
> It did reduce more hum than shielding only output transformers.
> But there was still very small amount of hum left, which disappeared when output transformers were also shielded.


 
  Can you give us the details and dimensions on those boxes?  I may try to see if I can get them fabricated somewhere.


----------



## heku

I just used some leftover sheet metal pieces which I had and welded them together.
  Power transformer box I tried to make so that there would be some ventilation. Its inside dimensions are few millimeters bigger than transformer itself and there are small feets which leave gap between circuit board and box.
  Output transformer box is just solid box that is in touch to circuit board.
  I protected nearby components and insides of boxes with dielectric material.
  Glue is used for securing boxes in place.
   
  I think you would get more accurate dimensions if you take measurements from your own amp.
   
  (If you are really anxious to try you could see if cardboard box and tin foil would work. I haven't myself tried this method.) Now I have tried this and it doesn't work.


----------



## tomb

Quote: 





heku said:


> I just used some leftover sheet metal pieces which I had and welded them together.
> Power transformer box I tried to make so that there would be some ventilation. Its inside dimensions are few millimeters bigger than transformer itself and there are small feets which leave gap between circuit board and box.
> Output transformer box is just solid box that is in touch to circuit board.
> I protected nearby components and insides of boxes with dielectric material.
> ...


 
  Well, the reason I asked is that it looks like what you put over the PT is simply some perforated sheet steel.  I would think some tin snips and a vise would be enough to form the box.  You concerned me when you mention "weld," though.  I'm actually quite surprised that the one over the PT has any effect at all with those perforations.  Welding would also not seem to be necessary - the open slots on the sides after bending can't be worse than all those perforations.  Frankly, it seems strange that the box is actually doing anything with all those holes. 
   
  Is it completely touching the sides of the PT?  There's very little clearance between the edges of the PT and the PCB pads for the rectifier leads.  Dsavitsk and I had considered trying this before, but it would be quite dangerous in that area with the proximity of the rectifier leads (especially the high voltage ones!).
   
  A couple of final questions - from your perspective, was the ripple audible enough to cause you distraction?  If so, what headphones were you using?


----------



## heku

Power transformer box has those perforations only on top. Box is touching transformer from one side because C1 is so close to transformer. There is dielectric material between transformer and box.
  IEC inlet side and two other sides have small gap between box and transformer for air flow.
  Here you can see those gaps:

   
  And here is picture from one side of the box where you can see gap between box and circuit board:

   
  Top side of the box is almost touching case lid, so maybe you could do box with side walls tall enough that they touch case lid and leave top side of the box off.


----------



## heku

It was audible with Sennheiser HD800 in high Z setting. With Denon D2000 I didn't hear any hum.
  With music playing I didn't notice it but when music paused it was quite noticeable.


----------



## tomb

Quote: 





heku said:


> It was audible with Sennheiser HD800 in high Z setting. With Denon D2000 I didn't hear any hum.
> With music playing I didn't notice it but when music paused it was quite noticeable.


 
  Well, I don't want to minimize your efforts, but I'm not sure a Sennheiser HD800 is an appropriate choice for this amp.  I have even said so to other individuals asking questions about it offline.  One would understand after spending $1500 on a pair of headphones that you would want perfect, absolutely noise-free amplification and would indeed, _be listening for just that_.  However, the Torpedo is on the forefront as a _DIY entry-level_, tube-transformer-coupled amplifier.  There is no other amp like it that's completely based on a PCB.  In that regard, I think it competes quite well with something like the Bottlehead Crack.  It's actually more versatile in its primary focus with low-impedance headphones such as Grados.  (I would note that the Denon is quite sensitive at 25 ohms.)  Yet, for the world's best dynamic headphones - the logical choice would be commensurate in quality with source and amplification, i.e, "the world's best."
   
  I understand that many people who purchase something like the HD800 may be tapped out in their resources and so resort to something more affordable in the rest of that audio string (source-amp-headphones).  It's also quite understandable that you went to these lengths to remove the last bit of hum and they are appreciated, I'm sure, by everyone here.
	

	
	
		
		

		
		
	


	



   
  However, I have some concerns and thoughts - some of which are based on those most recent photographs, others are my own review with the amp, its layout, and all the discussions that Dsavitsk and I have had:
   
  My concern is that any use of those steel boxes could be quite dangerous. The one over the PT is especially threatening. Somewhere over 200V exists in PCB pads and solder leads that are within a millimeter or two of the edge of that steel. Hell, if the soldering joint on one of those rectifier leads was a little messy, it could be touching.  (This is especially true if someone didn't even go to the trouble of getting the parts flush to the PCB - Dsavitsk and I have actually seen this.)  Similarly, if the amp takes a little jostling one of those boxes could come loose from those glue joints.  Neither the PCB or a steel box offers the kind of porosity needed for a truly robust glue joint.  I can't in good conscience recommend something like this or even provide it myself and depend on the builder installing it correctly and safely.
   
  Further, I'm no expert on shielding gaussian fields, but it doesn't make sense that it would work with all those perforations.  Maybe I'm wrong in that regard, _but Dsavitsk just repeated that the noise is also picked up in the circuit on the PCB_. He's done extensive scope tests in connsultation with several knowledgable people.  In any event, not even a perfectly-shielded box is going to prevent injection of the noise into the circuit on the PCB. The Zener diode mod, on the other hand, removed the last bit of noise to my satisfaction by virtue of its increasing the PSRR to the tubes and output. 
   
  I listen to my Torpedo every day and enjoy it immensely (along with the pup 
	

	
	
		
		

		
		
	


	




) - it's my primary amp with my Grado HF-1's and 2's, and also my HD600's. We honestly thought that we had removed the noise to the extent that some people might barely notice it, but others would not notice it all.  The Zener diode mod was what led me to conclude that things were pretty good.  Some of you may have noticed after that I black-anodized and laser-etched all the cases I had on hand. I even started offering _full_ kits. Maybe it was dumb on my part, but I have a bunch of new cases and transformers ordered and being manufactured as I type this. I wouldn't have done all this in the least if I thought we had anything more than a triviality.
   
  It may very well be that there are some headphones that are not really appropriate for this amp.  The HD800 may be one of those.  Just my own opinion (and beating a dead horse, I suppose), but I would never consider applying a $300 amp with $2 tubes to an HD800 and expect perfection.  However, heko has provided what appears to be a fix to his satisfaction and his work is commendable.  If someone else wants to go that route with an HD800, that's their choice, but I don't think I would personally recommend it.


----------



## KimLaroux

Tomb, this is DIY, your kits don't have to include all the possible modifications. 
	

	
	
		
		

		
		
	


	



   
  If you judge your kit to perform to an acceptable level, then you can pat yourself on the back and take a break. For me that's a success. You can then concentrate on distribution.
   
  But if builders find tweaks that presents improvements in their configurations (read - with their headphones), then let them share with the community. If others want to try them, let it be at their own risks. Tweaks don't always work for everybody, or are even necessary to everybody. But it's great to know, from a DIY'er standpoint, that the kit is open to all sorts of modifications with potentials improvements. Isn't this what's so exciting about DIY?
   
  I do agree with you that those metal boxes present electrical shorts hazards. Especially the PT one sitting over the rectifiers with nothing more than hot glue... lol. Actually when I asked about not shielding the PT in my last post, I expected those rectifiers to be part of the reasons not to shield it.
   
  As for perforations: If the hum is a low frequency, like AC hum, then it'll get filtered out my the box even if it has holes in it. Think Faraday cages. The higher the frequency of the radiation, the smaller the holes have to be. Wifi and cellphones RF needs solid ferrous metal to be shielded off. In my amp, I used iron cages with a hole in the top to shield the tubes from magnetic coupling from the PT. It works perfectly, even with this huge hole on the top.
   
  Another, safer approach to shielding in the Torpedo may be to mount metal plates to the top cover. Though it'll mean drilling holes in it, so anyone who'll want to experiment with this should get a spare top cover just for tests. It's something to try, anyways.


----------



## tomb

Kim,
   
  Part of my response has to do with several strings of parallel PM's that I had going on at the same time.  Sometimes my honesty is in direct conflict with my self-interests.  It gets frustrating with people asking me to recommend an amp and by the time I'm through with them, Beezar's amps are no longer considered.  It happens a lot.  Maybe it's all these $1500 headphones out there and I refuse to say a $100, $200, or $300 amp is the finest thing available (unlike some other people). 
	

	
	
		
		

		
		
	


	



   
  I certainly agree with the DIY aspect and would never, ever restrict anyone's experimentation, except when it comes to a safety issue - and I think this may be one of those.  It's probably a moot point, since not many people are going to go to the effort to _weld_ a steel box.  Still, you would be shocked (pardon the pun) to see what some people will do, even in the face of killer voltage.  I'm not saying at all that's what heku has done.  Indeed, heku's work is greatly appreciated and I stated so - plainly.  Others may not have the skills involved, though, and the Torpedo is supposed to be an entry-level, high-voltage amp suitable for someone who's never messed with high-voltage before.  Heck, it's the first and only high-voltage amp I've ever built.
   
  Meanwhile, we have and will continue to tweak the amp and if there is mod worth considering with beneficial results, it'll be incorporated and documented as quickly as possible.


----------



## yuujin

Thanks tom for the invaluable kits that are close to effortless to build.


----------



## dustinsterk

Hello all,
  A little off topic but does anyone have any comparisons on the Torpedo vs Bottlehead crack.  I am torn what to build next but am leaning toward the Torpedo.  I have not heard either but will be driving my HD600s with one of these two amps and am looking for a recommendation.
   
  Thanks in advance.
   
  --Dustin


----------



## RustA

Quote: 





dustinsterk said:


> Hello all,
> A little off topic but does anyone have any comparisons on the Torpedo vs Bottlehead crack.  I am torn what to build next but am leaning toward the Torpedo.  I have not heard either but will be driving my HD600s with one of these two amps and am looking for a recommendation.
> 
> Thanks in advance.
> ...


 
   
  PMed you about the question...


----------



## catfish

Can anyone recommend a cinema are similar transformer for the input of this to take a balanced connection (my DAC has balanced out and is quite a distance from the amp.)


----------



## nikongod

Quote: 





catfish said:


> Can anyone recommend a cinema are similar transformer for the input of this to take a balanced connection (my DAC has balanced out and is quite a distance from the amp.)


 
   
  Did you mean Cinemag? 
CMLI-15/15B


----------



## RustA

Quick report:
   
  The amp arrived and my friend helped me to assemble it, including several tweaks mentioned here... I don't have an idea how significant the hum is without them, but it is unhearable on low impedance/gain setting and gets noticable only at 75 - 100 % volume on high setting with Sennheiser HD800. Since I use StageDAC with 2.2vrms output and have no need for replaygain, it's absolutely a non-issue (I don't get past 25% actually). *Therefore, this amp is practically dead-silent even with HD800*! My friend offered me to tweak the amp even more but I have no need for that right now.
   
  The Torpedo looks very very very nice, way better than on the promo photos... It's actually cute and compact, not much heavy. The casing gets covered by dust quite easily but it's not really an issue for me.
   
  As for the SQ, I would say more or less on par with O2... It's not the same sound and the results with Torpedo also depend on tubes but I don't see any of those two as superior (just significantly different). However, I have to state that I don't subscribe to audiophoolery and really didn¨t manage to hear a BETTER amplifier than O2 in category up to 1000USD (didn't bother to try anything more expensive). I don't really understand all that talk about how one amplifier KILLS the other one... Maybe imagination and placebo are not strong enough with me. 
	

	
	
		
		

		
			




   
  TomB told me that this amp has zero harshness... I feel this is significantly dependent on tubes you use ( = it's not true everytime). I've tried six different pairs and while they sound all similar, there are differences that become obvious especially when you are searching for the right "synergy" with your DAC and headphones to finalise the chain.
   
  I must say that I really enjoy the amp in combination with StageDAC (hardware crossfeed FTW!). I have tweaked the crossfeed and the other settings to offer the best sound for me, and then chose the right set of tubes to balance the signature. I don't find the Torpedo to be *mind-blowing* but it works very well with HD800 - doesn't exaggerate the soundstage and works as a little EQ as well (tubes!). I would say that I knew why to purchase this amplifier and got exactly what I was expecting - *a quality and versatile tube amplifier* -  nothing more, nothing less.


----------



## tomb

Many thanks for such a fine review, RustA!!  I'm glad we sent all those tubes.  It's very nice to know that it can pair well with HD800's. 
	

	
	
		
		

		
		
	


	



   
   
  P.S. Dust is a sometime nuisance on mine, too.  I thought it was just me, but I wouldn't want to change back to silver.


----------



## DingoSmuggler

Quote: 





rusta said:


> TomB told me that this amp has zero harshness... I feel this is significantly dependent on tubes you use ( = it's not true everytime). I've tried six different pairs and while they sound all similar, there are differences that become obvious especially when you are searching for the right "synergy" with your DAC and headphones to finalise the chain.


 
  Because torpedo tubes are all about 50 - 60 years old, when first using a set of tubes they won't perform so well for the first few hours. They need a bit of time for the getters to do their thing and restore the vacuum inside. So don't judge any tube on initial impressions. But even after all that, some of my torpedo tubes are a bit crappy sounding.
  I think my best overall performers would be dumont 5964s i got from tomb.


----------



## RustA

Quote: 





dingosmuggler said:


> Because torpedo tubes are all about 50 - 60 years old, when first using a set of tubes they won't perform so well for the first few hours. They need a bit of time for the getters to do their thing and restore the vacuum inside. So don't judge any tube on initial impressions. But even after all that, some of my torpedo tubes are a bit crappy sounding.
> I think my best overall performers would be dumont 5964s i got from tomb.


 
   
  I understand, thank you! I am not really a fan of pink-noise burn-in or similar - just listening and enjoying  I chose one of the sets TomB shipped to me that works well with the rest of my chain from the start, we will see how it develops with time... I will most probably try all the sets once again today since it is always better to decide through several listening sessions (to avoid wrong judgement due to fatigue or placebo).
   
  Quote: 





tomb said:


> Many thanks for such a fine review, RustA!!  I'm glad we sent all those tubes.  It's very nice to know that it can pair well with HD800's.
> 
> 
> 
> ...


 
   
  I would like to thank you as well - all the content was packed REALLY well and there were no problems during the building process. My friend likes the amp as well but it's too revealing for him (he is not an audiophile really and only listen to lossy audio files).
   
  The report above was really only a report - it is for sure that I couldn't assess the amp properly after only several hours of listening and tweaking my system... I need more time to spend with my favourite music and will post my more developed impressions afterwards here. 
	

	
	
		
		

		
		
	


	



   
  I must stress that I chose my "endgame" setup having versatility/options as a priority. HD800 are extremely comfortable, have imaging, separation and soundstage like no other headphone I have ever heard and offer very neutral frequency response. Then, the StageDAC has many options how to tweak the signal - crossfeed with several settings, tonal balance, over-sampling, pulse response... Finally, Torpedo offers low/high impedance switch to work well with different headphones + its tube nature is suitable for perfecting the chain with small sound adjustments, to balance the rest. This was my primary goal since I am not a "detail-head" or "ultimate audiophile". I wanted to get a natural sound and combine advantages of both speakers and headphones sound while staying safe in terms of money - and I must say this is definitely possible with HD800, hardware-based crossfeed and this nice tube amplifier.


----------



## KimLaroux

Quote: 





dingosmuggler said:


> Because torpedo tubes are all about 50 - 60 years old, when first using a set of tubes they won't perform so well for the first few hours. *They need a bit of time for the getters to do their thing and restore the vacuum inside.* So don't judge any tube on initial impressions. But even after all that, some of my torpedo tubes are a bit crappy sounding.
> I think my best overall performers would be dumont 5964s i got from tomb.


 
   
  I believe the getters are always active, even when the tubes are in storage and not used. They are just a layer of metal that react with gases inside the tube and "absorbs" them by oxidation. They are independent of the tube being powered or not. If a tube has been infiltrated by gases, powering it won't change much.
   
  I do agree that most tubes will change characteristics after a few hours. I haven't learned what may be responsible for this yet, but I'm pretty sure it does not involve the getters.


----------



## tomb

Quote: 





kimlaroux said:


> I believe the getters are always active, even when the tubes are in storage and not used. They are just a layer of metal that react with gases inside the tube and "absorbs" them by oxidation. They are independent of the tube being powered or not. If a tube has been infiltrated by gases, powering it won't change much.
> 
> I do agree that most tubes will change characteristics after a few hours. I haven't learned what may be responsible for this yet, but I'm pretty sure it does not involve the getters.


 
  I think you are correct in theory, but maybe not in practice. 
	

	
	
		
		

		
		
	


	




  The getter "flash" is the silver deposit on the inside of the glass.  It's produced the first time by heating the getter itself, which usually has barium on it (from what I've read).  The high heat will "flash" the barium over to the glass, producing the silver splotch.
   
  You are correct that the silver splotch will continue to react with gas in the tube whether the tube is on or not.  This is easy to see if you've ever broken a tube, because the getter flash will turn white almost instantly in the presence of the oxygen in air.  However, heating the tube back up after a few decades of storage may still release additional barium from the getter, aiding the cleansing of the tube from gas.  Plus, heat will speed up almost any non-exothermic reaction, so the removal of residual gas is still aided by having the tube "run-in" for awhile if it's been a NOS tube in storage for a number of years.


----------



## vixr

I read that the use of a tube socket can sometimes shorten the life of a tube by not allowing enough thermal expansion...causing micro cracks around the pins.  
	

	
	
		
		

		
		
	


	




  I will take more care in the future to ensure that no adhesive gets on the tube socket connectors when I remove the rivet for an LED and glue the ceramic back together.


----------



## KimLaroux

Quote: 





tomb said:


> I think you are correct in theory, but maybe not in practice.
> 
> 
> 
> ...


 
   
  That's a valid argument. Heat may speed up the process. Raising the temperature also means particles which need a higher energy to react have a higher probability of doing so.
   
  But honestly, there's no way powering it up again will release more barium. This stuff boils at 1897 °C (3447 °F). I doubt a tube gets that hot. It is originally flashed using radio frequency of the type used in microwave ovens.
   
  So, anyone willing to "burn in" a NOS tube using a microwave oven? 
	

	
	
		
		

		
		
	


	



   
  (honestly, don't, that's a joke)


----------



## tomb

Quote: 





kimlaroux said:


> That's a valid argument. Heat may speed up the process. Raising the temperature also means particles which need a higher energy to react have a higher probability of doing so.
> 
> But honestly, there's no way powering it up again will release more barium. This stuff boils at 1897 °C (3447 °F). I doubt a tube gets that hot. It is originally flashed using radio frequency of the type used in microwave ovens.
> 
> ...


 
  There are a lot of other materials used besides Barium.  I'll admit that I didn't look up the vaporization temperature, but you seem interested enough to read this, maybe you can tell us why the old advice about burning out residual gas in NOS tubes is a lie:
http://www.emissionlabs.com/Articles/GETTER/getter.htm
   
  Besides, why wouldn't adsorbed gas on the surface of the plates vaporize easier under heat so that the getter flash can react to it?  I'd rather believe the old advice - I'm satisfied that there's enough going on to provide ample explanation for reducing the gas when the tubes are on.


----------



## KimLaroux

Quote: 





tomb said:


> There are a lot of other materials used besides Barium.  I'll admit that I didn't look up the vaporization temperature, but you seem interested enough to read this, maybe you can tell us why the old advice about burning out residual gas in NOS tubes is a lie:
> http://www.emissionlabs.com/Articles/GETTER/getter.htm
> 
> Besides, why wouldn't adsorbed gas on the surface of the plates vaporize easier under heat so that the getter flash can react to it?  I'd rather believe the old advice - I'm satisfied that there's enough going on to provide ample explanation for reducing the gas when the tubes are on.


 
   
  I've never said it's a lie, so no I can't tell you why it would be one. In fact, in my last post, I agreed with you about heat improving the efficiency of the getter. And I still agree with what you're saying here. I have nothing to say against it. It makes perfect sense. 
   
  This web page is amazing, thanks for the link.


----------



## tomb

Quote: 





kimlaroux said:


> I've never said it's a lie, so no I can't tell you why it would be one. In fact, in my last post, I agreed with you about heat improving the efficiency of the getter. And I still agree with what you're saying here. I have nothing to say against it. It makes perfect sense.
> 
> This web page is amazing, thanks for the link.


 
  I misinterpreted.  Sorry. 
	

	
	
		
		

		
			




   
  Yeah, there's been a lot of science on getters, apparently.


----------



## RustA

Are there any specs available on this amp? Like how much power/current does the amp output into low impedance and high impedance, at least?
   
  I should also tell more about the hum - my friend did the zener mode, a choke, grounding heatsinks and followed heku (images on page 24). The result is zero hum... I realised that what I am hearing on 75 - 100% on high Z with HD800 is not a hum but simple low-level hiss.
   
  The only case when I can actually hear hum is when I output digital signal from my desktop computer using coaxial (to my DAC) as there seems to be a VERY noisy environment inside the PC...


----------



## dsavitsk

Somewhere between 125mW and 250mW -- depending on how hard you push it, and what sort of distortion you are willing to live with. So that means ~ between 6 and 9Vrms into 300 Ohms, and between 2 and 3Vrms into 32 Ohms


----------



## cubeasic

Maybe a stupid question from a person that never used tubes and output transformers before: Would the torpedo be able to function as a preamplifier with the right adapter? So, could it drive 20k impedance? 
   
  Of course, preamp function would not be necessary, but this way, I could try a "genuine" tube pre with my speakers, to see how that sounds.


----------



## dsavitsk

The very short answer is that the inductance of the transformers determines whether a load is too high. If there is not enough inductance, you will lose bass. These transformers may drive a 20K load, but it would probably be prudent to put a dummy load (a resistor) across the secondaries.


----------



## RustA

*Little bit more about my impressions on the Torpedo (EDITED!)*:
   
   
  I tried all the tube sets once again and what surprised me was that the variation in FR is not as significant as I expected before getting the amp. TomB sent me 3 different matched 6J6 sets (with different subnames on it), one pair of 6J6W, 5964 and 5844 = 6 matched pairs in total. I am not able to precisely speak about each subtle difference but in general, this is my personal opinion so far with HD800 and StageDAC:
   
  1) *6J6 (Top UFO)* - cannot say how it is possible but this set has significantly better soundstage width... I mean SIGNIFICANTLY. The rest of tubes are rather similar in this regard but this set beats them all just because of this parameter. Strange, I didn't play them more than the rest... I thought it's a placebo but it's not, no problem to do a blind test here and recognize the difference o_O
   
  2) *6J6W* - looks beautiful when plugged because only those are completely transparent from the top and therefore you see that beautiful visual effect of tubes to the full extend. As for the sound, so far similar to the rest of 6J6 series.
   
  3) *5964, 5844* - Not sounding completely the same but I prefer 6J6 tubes over them so far, not by much at all though... The differences are very small and it could happen that for some specific reason (sound-wise) one of them will become my favourite in future.
   
   
   
*Now a little bit more on the sound*, in comparison to O2 as a VERY GOOD solid state amplifier (using the same cable and 1/4 headphone out on both amps = no adapters). I still think those two are on par but provide a SIGNIFICANTLY DIFFERENT experience (I mean SIGNIFICANTLY IN TERMS OF AMPLIFIERS...):
   
_*O2*_ is clear, airy, transparent, "monolithic" sound-wise, neutral... Just easy to assess, nothing to stay hidden (I mean in terms of its sonic characteristics), nothing complicated.
   
_*Torpedo*_ is much more complicated... It's not as clear, airy or transparent (yes, it's not a completely transparent amp). However, there really is zero harshness, imaging is on par with O2 and with 6J6 tubes (see above), Torpedo beats my O2 in soundstage significantly (O2 still a bit wider but Torpedo much more natural and near-perfect, at least for music I like, IMHO). Frequency response leaning towards the warmer side (not dramatically though)... Highs are *very nice* (natural guitars and cymbals in comparison to rather lifeless and harsh interpretation given by O2, most probably due to impedance match issues), voices as well full and beautiful, bass is there but lacks tightness and ultimate impact so far, regardless the tubes I use. O2 bass is analytical but present, with relative ease...
   
  Both are in the same league IMHO but I am surprised that O2 really suffers from impedance mismatch with HD800... The highs (including female vocals) lack smoothness and detail - yes, detail! It seems TomB was right here, it seems near-zero impedance really isn't ideal for all. Torpedo, on the other hand, lacks complete transparency O2 provides. The difference is not big but for those of us who consider transparency very important (hi, David!), this could be an issue (to solve with the rest of a chain). Especially with warmer headphones.
   
   
   
So far, I struggle to choose which of those two amps to prefer... They are both really good in what they provide. I guess it would be good to get some magical set of tubes which could tighten up the bass (lower subbass frequencies a little to clear up the sound) and maybe brighten the overall signature a bit ( = to increase a perception of transparency = less subbass could do the job as suggested previously). Maybe if I burn-in all the sets of tubes, one of those would do the job... We will see. 




   
*EDIT*: After tweaking my StageDAC's setting, I found out that:
   
_*A)*_ mid-position of Tonal balance switch gives the amp the bass impact it needed (it puts emphasis on frequencies up to 2khz to balance out the crossfeed effect), without loosing the separation completely (bass moves more up to the center where singer's position is which I find more natural than rather analytical approach with HD800 "stock" bass, positioned significantly below singer and guitars). Listening is now more near to the way how speakers do sound, significantly... And the bass is more on the scene, in terms of both position and impact/subjective feeling of tightness. Image-wise it's a bit worse but nothing I cannot live with.
   
*B)* Low-positions of Pulse response and Over sampling gives the sound the last touch of brightness it needed to feel reasonably transparent ( = low Pulse and Low Oversampling means classic DAC approach = completely flat line from bottom to the absolute top). Those few added db of high treble frequencies helped to complete the synergy. God bless the StageDAC!
   
  I am now ready to spend few days with the setup to ensure that the synergy now really is satisfactory to near-full extent, at least. The amp still could be a touch more transparent in order to be "perfect" itself (bass is alright in the end for me, just not as punchy without my StageDAC), let's see what burning in the tubes brings!
   
   
   
*Disclaimer*: Please, take it rather as a temporary opinion  But it could help or at least interest someone enough to give an advise or another opinion. There aren't many posts about how Torpedo actually sound... Well, right now, one more added ,-)
   
*Disclaimer** 2*: O2 haters, skip all my opinions and please do not underestimate this tube amplifier... It could very well outperform O2 for you in every aspect. I personally have high respect for O2 and now for the Torpedo as well.


----------



## cubeasic

Quote: 





dsavitsk said:


> The very short answer is that the inductance of the transformers determines whether a load is too high. If there is not enough inductance, you will lose bass. These transformers may drive a 20K load, but it would probably be prudent to put a dummy load (a resistor) across the secondaries.


 
  ok, makes sense. 
   
  Thank you. 
  Florian


----------



## tomb

Quote: 





rusta said:


> *Little bit more about my impressions on the Torpedo (EDITED!)*:
> 
> 
> I tried all the tube sets once again and what surprised me was that the variation in FR is not as significant as I expected before getting the amp. TomB sent me 3 different matched 6J6 sets (with different subnames on it), one pair of 6J6W, 5964 and 5844 = 6 matched pairs in total. I am not able to precisely speak about each subtle difference but in general, this is my personal opinion so far with HD800 and StageDAC:
> ...


 
  Just an FYI, but I used the descriptor "UFO" because the getters look to me like tiny flying saucers.   As best I can tell, they are 50's-vintage Japanese tubes.  Maybe they were left by the Mysterians?


----------



## RustA

Quote: 





tomb said:


> Just an FYI, but I used the descriptor "UFO" because the getters look to me like tiny flying saucers.   As best I can tell, they are 50's-vintage Japanese tubes.  Maybe they were left by the Mysterians?


 
   
  Haha, that would be awesome... Hell, no! I need to get another pair somehow to be safe, these really sound great! 
	

	
	
		
		

		
		
	


	



   
  =====================================
   
  After spending another day with the amp, I must say that the tweaking really perfected my experience and therefore I definitely started to prefer the Torpedo over O2 for HD800.
   
  There is singnificantly more detail and texture in higher mids and treble, most probably due to better impedance match (using high Z switch for 300 ohm all the time, of course!). With my favourite tubes, soundstage is very natural... I only hope the tubes won't change to worse early =/
   
  In general, I would describe my whole chain as a hybrid of HD800 and LCD-2 type of sound - great impactful bass, liquidy mids, non-harsh highs, wide but not too wide soundstage and very good imaging (though not as brilliant and accurate as with HD800 stock since I have crossfeed on along with Tonal balance switch). Separation is also not as brilliant but still significantly better than with LCD-2. That said, if I want to get the HD800s sound back, I just turn off the Tonal balance switch => perfect imaging and separation is there 
   
  Nothing is perfect but I am very happy with my audio chain right now, from the player to the headphones... As a student, I cannot afford anything better but I feel that my system is brilliant for the price.
   
  =====================================
   
  As for the sound of the Torpedo itself, my opinion remains unchanged - the amp is very good, has a lot of texture and no harshness. Its sound is very natural and the impedance switch makes it a very versatile device, along with tubes, of course! With the right pair, soundstage gets pretty good... I would like the amp to be a little bit more transparent and precise in rendering bass guitar but as I said - it's possible to mitigate with the rest of your chain, or maybe even with the right set of tubes. Will keep it definitely!


----------



## tomb

Quote: 





rusta said:


> Haha, that would be awesome... Hell, no! I need to get another pair somehow to be safe, these really sound great!
> 
> 
> 
> ...


 
  Thanks for the awesome posts.  I have plenty of the "Mysterian" 6J6's - just specify that's what you want if you order more.


----------



## RustA

Quote: 





tomb said:


> Thanks for the awesome posts.  I have plenty of the "Mysterian" 6J6's - just specify that's what you want if you order more.


 
   
  PMed you


----------



## heku

I noticed that power transformer was making more noise because metal box was touching it.
  So I moved C1 further away from transformer and made little bit bigger box.


----------



## RustA

*Update after one week of listening / tweaking (EDITED, again!)*:
   
  I upgraded both my computers - exchanged my old laptop for brand new dedicated audio PC which is very silent and reasonably priced (my friends helped me to get the absolute best for my money). Then, I purchased a very good fan regulator in order to tune all my six fans in my control PC to be as silent as possible. I also estimated the final and best setting for me in Jplay and StageDAC and...
   
  ... I am amazed how brilliant my system sounds! I praise Torpedo's very natural approach which completely balance my whole chain and adds LIFE to it... The amp offers a very natural tone with slight fullness or heaviness that helps drums or piano to have a real impact. It slows music down a little bit, subjectively. I love how my HD800 have a bit dark-ish tone now, kind of LCD-2 like sound with much better soundstage, neutrality and technical brilliance. 
	

	
	
		
		

		
		
	


	




 Zero brightness or sibilance but still the detail and separation are there (no need for StageDAC's tonal balance correction anymore). Bass is very relaxed and smooth, I kind of love its less analytical and more butter-smooth and sugary feeling... It's creamy and relaxed but enough tight and precise, the best bass I have heard with headphones! Mids are very natural, very similar to LCD-2s (voices!) and treble more neutral in comparison but very very smooth (loving those guitars - both acoustic and electric)! My little complaints about bass tightness and transparency are finally gone!
   
  Man, this is perfect... My endgame rig for sure! It can be quite a task to implement Torpedo correctly into your audio chain but once its done, it's a symphony! I think Torpedo is a *BRILLIANT* device especially if you are looking for natural sound and have a little bit patience to find the right synergy with the rest of your system! 
	

	
	
		
		

		
		
	


	



   
  EDIT: It's incredibly speaker-like! Huge impact, heavy guitars, bass, drumming... Yeah, hardware-based crossfeed + natural-sounding tube amplifier + HD800 = 
	

	
	
		
		

		
		
	


	












   
  Thanks TomB!!!


----------



## dsavitsk




----------



## RustA

Quote: 





dsavitsk said:


>


 
   
  Thanks to *you* as well! One of the best nights in my life, it brought tears to my eyes several times, really... After all I did in previous five months (or nearly two years, to be precise), I have a feeling that I reached the milestone. This is what I wanted to achieve during my studying years - it took several high-end headphones, amps, DACs and players but it's here and it's real! Now, I am free to focus on music and be looking forward to future upgrades once anything interesting appears on the market - wish to get even closer to how speakers sound with headphones!


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## RustA

To be more useful, here are several images of my amp:
   

   

   

   

   

   
  Using DAC with 2.2vrms output and toslink (and no DSP like Replaygain), I get zero hum (electrical noise) with my Senns. On high impedance/gain mode, I hear low-level hiss on 75% and higher... That said, it's absolutely nothing to worry about since I never pass 20% of the overall volume. On low impedance/gain mode, there is no hum and no hiss at all.


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## tomb

Interesting that your new "hum shields" have no tops at all.  I suspected as much from early on.  It may simplify the potential improvement needed, if desired.  Again, it depends on the headphone.  I've reached nirvana with HF-1's and the pupDAC using my Torpedo with no mods at all.  It's funny, because my HF-2 seems a bit deficient in the highs by comparison.  I also have the SR-225's, but their highs seem exagerrated with somewhat deficient bass.  The HD600's with Cardas cables come close to the HF-1's, but are still a bit slow in the highs.  My only question is whether a pair of RS-1's are better than the HF-1's or more like the HF-2's.  I'm hoping the CanLanta meet will let me find out.
	

	
	
		
		

		
			




   
  Just MHO, but I find the very old NOS 6J6's the best as opposed to the "Mysterians" Japanese tubes, but that's just a personal preference.  My Grados need some mellowing amongst all the detail and maybe that's what I'm attracted to.  I like the Sonotone 6J6W's, some of the JAN 6J6's and then the DuMont/RCA 5964's.  It's crazy that all these tubes are available in the tens of thousands for $2 and less.  Dsavitsk had a stroke of pure genius with creating an amp based on these tubes. 
	

	
	
		
		

		
		
	


	



   
  Anyway - also wanted to say that I like the black knob better, too.
	

	
	
		
		

		
		
	


	




  I think I'll make them all that way unless someone asks.  Nice photos!


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## tintin220

I'm about to put an order in and just get the long kit to save me the trouble of ordering parts from Mouser, etc. Does this kit contain the parts for the recommended mods (zener, etc.)?


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## RustA

Quote: 





tintin220 said:


> I'm about to put an order in and just get the long kit to save me the trouble of ordering parts from Mouser, etc. Does this kit contain the parts for the recommended mods (zener, etc.)?


 
   
  Yes, order a full kit and you get EVERYTHING you need, including mods like zener or choke... That said, you have to tweak the amp yourself to get rid of hum that could possibly occur (see mine or heku's images for a basic guideline).


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## tintin220

Quote: 





rusta said:


> Yes, order a full kit and you get EVERYTHING you need, including mods like zener or choke... That said, you have to tweak the amp yourself to get rid of hum that could possibly occur (see mine or heku's images for a basic guideline).


 
   
  Great, thanks for the info. I've always wanted to listen to a parafeed amp and see how it sings with my Grados, especially compared to the WA6.


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## heku

I changed bias setting LEDs (D10, D11) to green ones (http://www.mouser.com/ds/2/239/_100_LTL2R3KGKNN-53107.pdf) and sound got better.
  With standard red LEDs bias was 2.25V now it is 2.47V.


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## tintin220

Quote: 





heku said:


> I changed bias setting LEDs (D10, D11) to green ones (http://www.mouser.com/ds/2/239/_100_LTL2R3KGKNN-53107.pdf) and sound got better.
> With standard red LEDs bias was 2.25V now it is 2.47V.


 
   
  Please define better. Does it measure differently? What are the differences as far as SQ in your opinion, as traits you may think are better might be worse to someone else's tastes? I'm still in the process of moving but once I get settled into my new apartment, I'll be ordering one of these kits to build. I sold my WA6, but I have one on loan from a friend that I can compare it to. Are there any other amps people want me to try for a comparison?


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## dsavitsk

The higher bias theoretically runs the tube in a more linear region. The problem with it is that it increases the plate voltage which limits headroom a bit. We used red since we thought it was a good tradeoff between sound quality and headroom. If you are not clipping with green and it sounds better, then by all means you should do it.


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## heku

I am not very good at describing sound, but I can hear new things from music and everything seems little bit clearer.
  Plate voltage increased about 10V, it is now around 180 and 170V. I am using Russian 6N15P tubes and plate voltage with these tubes is higher than any other tube I have tried.


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## RustA

If anybody interested: http://www.head-fi.org/t/661655/fs-torpedo-parafeed-tubeamp-2013-edition-assembled-tweaks-matched-tubes-bargain-worldwide-shipping#post_9420373
   
  As I said before in this thread, this amp is BEAUTIFUL in appearance and performance as well... That said, I had to find an amp suitable for powering both full-size headphones and IEMs/earbuds (got a killer deal on Concerto) and cannot afford having both at once.
   
  I am able to switch to both 110v or 220v... More info in the listing.


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## heku

I wanted to try increasing CCS impedance, so I changed 2N5087 transistors to BC560C. I also changed bias transistors to BC560C.
  And again sound got better.


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## tomb

Quote: 





heku said:


> I wanted to try increasing CCS impedance, so I changed 2N5087 transistors to BC560C. I also changed bias transistors to BC560C.
> And again sound got better.


 
  Thank you for continuing to experiment, but I'm not sure I agree that changing 2N5087's to BC560C's are going to make any audible difference.  They should be fully equivalent in this instance.  Some more tube rolling would probably have a much greater effect than changing transistor type.  JMHO ...


----------



## heku

Diffence in sound was about same when I changed bias LEDs.
  I measured transistors hFE using multimeter, for 2N5087's it was about 330 while BC560C's measured about 590.
  For anyone doing this mod, BC560's have different pinout, so they go backwards on board compared to 2N5087's.
  I used BC560C's just because I had those on hand, other transistor types might also work.


----------



## tomb

Quote: 





heku said:


> Diffence in sound was about same when I changed bias LEDs.
> I measured transistors hFE using multimeter, for 2N5087's it was about 330 while BC560C's measured about 590.
> For anyone doing this mod, BC560's have different pinout, so they go backwards on board compared to 2N5087's.
> I used BC560C's just because I had those on hand, other transistor types might also work.


 
  No offense, but I've had 2N5087's measure as high as 600-700, but I don't think that matters a bit the way they're connected.  Of course - other transistors will work - because it makes little difference.  Just color me skeptical on this one.


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## Punnisher

Just put an order in for the kit and am excited to start building. I decided to go the DIY route for the value. Plus this amp will work with varying impedances which can't be said for many tube amplifiers.


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## Punnisher

Received the kit on Saturday and had it built four hours later. I've been listening and doing initial break-in for the last day or two.
   
  Initial impressions are extremely positive. Really love the way this amp sounds with every headphone I own. The soundstage seems to be quite large and airy with this amplifier. With my other gear there seems to be a "gap" in the middle making imaging seem unnatural. With this amp though, imaging is more seamless and really helps place you in the performance. Another positive difference I've noticed is with bass and kick-drum. Huge bass transients are no match for this amp. I've never heard the kick drum sound so punchy and pronounced.
   
  The impedance switch seems to do well with under 200ohm on low and over 200ohm on high. That's my initial impression anyway with the varying impedances I've tried. My dt880 250ohm really sings on the high impedance setting with a flat yet full-bodied sound throughout all frequencies. The same can be said for my 120ohm k601 on the low impedance setting. Headphones that fall in the middle between 120 and 250 ohm could go either way. It's a great feature for a headphone collector who can't be tied down to one impedance range.
   
  There's only a couple issues I have found with my amp, and these are very very minor.
   
  1. A tiny bit of hum is audible for me during silence. It mostly shows up with very sensitive headphones (Grado) or headphones that are middle-of-the-road impedance on the high setting (dt880 250ohm). It should be noted that I have not tried the numerous tweaks available and that I have an older house which does not have grounds on any of its outlets. Once I attach the amp to a properly grounded outlet the hum may disappear completely. Combined with the tweaks, I am confident I can get the amp to be dead silent. With that said, it doesn't take away from enjoyment at all and should not be a deterrent from buying this awesome kit.
   
  2. I only found 3 short black screws in my kit. It would be useful to have 6 short screws for the standoff mounting. I ended up stacking washers with the long screws inside the amp which gets very close to the output transformer leads. I'll be shortening those screws and reinstalling them soon.
   
  Thanks to everyone involved with designing and distributing this kit. It's absolutely fantastic.


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## perrew

Wanted to try and ecp l-2 but they were all sold out so I got the next best thing instead....a torpedo. I really like this amp!


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## HiGHFLYiN9

Very cool vent holes! How did you pull that off?


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## Punnisher

Yes we must hear what you did for that project. Paint? Powdercoat?
  
 I have been enjoying my amp very much. My latest pairing is the K702 with 6J6 tubes using low impedance setting. This combo sounds very nice, natural, spacious. I also made a few tweaks including stainless machine screws, clear anodized aluminum knob and tube guards. I like the way it turned out.


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## tomb

Very nice, Punnisher!
  
 That blue one was one of the first prototypes.  It was custom machined/powder-coated by user luvdunhill.


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## tomb

punnisher said:


> <snip>
> 2. I only found 3 short black screws in my kit. It would be useful to have 6 short screws for the standoff mounting. I ended up stacking washers with the long screws inside the amp which gets very close to the output transformer leads. I'll be shortening those screws and reinstalling them soon.
> 
> Thanks to everyone involved with designing and distributing this kit. It's absolutely fantastic.


 
 The short screws are only for one side of the standoffs - they're only supposed to be 3 of those in the kit.  The rest of the screws will fit on the other side.  All screws are selected for a minimum of one washer under the screw.  On the top of the PCB, you should use one washer and a lock-washer.  This cuts down on the possibility of loosening the PCB screw, first.  It should stay tight when you loosen the screw on the bottom of the case.  This is the same for all three standoffs.
  
 I suppose I should write another web-page just on hardware, since the screws and washers/etc. included with the kit are extensive.


----------



## perrew

tomb said:


> Very nice, Punnisher!
> 
> That blue one was one of the first prototypes.  It was custom machined/powder-coated by user luvdunhill.




Yeah I got it from luvdunhill and it is an amazing build with beautiful sound.
Ive been running it with a Pico Dac and it sounds great with the HD800s. 
A really nice amp! Tks Dsavitsk/Beezar!


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## tomb

punnisher said:


> Received the kit on Saturday and had it built four hours later. I've been listening and doing initial break-in for the last day or two.
> 
> Initial impressions are extremely positive. Really love the way this amp sounds with every headphone I own. The soundstage seems to be quite large and airy with this amplifier. With my other gear there seems to be a "gap" in the middle making imaging seem unnatural. With this amp though, imaging is more seamless and really helps place you in the performance. Another positive difference I've noticed is with bass and kick-drum. Huge bass transients are no match for this amp. I've never heard the kick drum sound so punchy and pronounced.
> 
> ...


 
  
 OK - I blew it.  You are absolutely correct about the screws/washers.  I just built two recently and I must've messed up when originally coming up with the hardware pack.  The standoffs work best with 1/4" screws on both sides:

On top of the PCB - 1/4" socket head, lock washer, washer
Underneath the PCB - Washer, standoff
Bottom of case - washer, 1/4" socket head screw.
  
 I've also noticed some quality-control issues on the Hammond choke.  Not that it hurts anything about the circuit, but the metal tabs and frame of the choke have some variances that require more hardware - specifically, a washer under the tabs.  So, for the choke you have this for each mounting tab (2 of them):

On top of mounting tab - 1/4" socket head, washer
Underneath mounting tab, on top of PCB - washer
Underneath PCB - washer, lock washer, nut
  
 As someone also pointed out, the back stand off (closest to the PT) is also too close to the 200V B+ trace that cuts across the width of the PCB.  A regular washer touches the trace and if you clamp down too hard or scratch the mask, you'll have a short.  I will supply a nylon washer with all hardware in the future.  We'll fix that with the next revision of PCB's.
  
 Speaking of which, I'm pretty excited about a tweak that I've been supplying with the last few kits.  It reduces any trace of the ripple with my Grados and further improves the sound quality of the amp.  Dsavitsk told me that Kevin Gilmore suggested that the heater power supply was oscillating at the rectifiers.  This makes sense, because it's never "hum" (60 Hz).  It's a 180 Hz artifact that only presented itself when the case is buttoned up.  None of that made sense with typical 60Hz hum.  By default, however, we used very fast Schottky rectifiers for the heater supply and those appear to be causing oscillation.  The noise (as small as it was) has always seemed to favor the left channel, too, which is where the heater supply rectifiers are located.
  
 Anyway, we went to general purpose diodes and small snubber capacitors for the last couple of kits.  There is really no need for super-speed rectifiers to power just the tube heaters.  The DC requirement is only there to prevent any 60Hz hum, which has never been a problem.  The two Torpedoes that I just built recently used this combination of rectifiers and snubber capacitors and the amp has never sounded better or more quiet.  As I said, I can no longer detect any noise at all with my Grado HF-2's.
  
 The rectifiers are BY228GP-E3 - Mouser Part #625-BY228GP-E3.  The snubber caps can be numerous possibilities - just look on the Millett MAX, MiniMAX, or MOSFET-MAX BOM's for suggested equivalents.  I used SA102A101JAR, again at Mouser Part #581-SA102A101JAR.  All you need do is to solder a snubber cap in parallel across a rectifier.  This is best done on the bottom of the PCB.  Don't solder the snubber caps across two rectifiers, or you'll cause a short - just piggyback each snubber cap across each rectifier.
  
 I'll detail all of this on the Torpedo website when I get a chance.


----------



## jdkJake

tomb said:


> Speaking of which, I'm pretty excited about a tweak that I've been supplying with the last few kits.  It reduces any trace of the ripple with my Grados and further improves the sound quality of the amp.  Dsavitsk told me that Kevin Gilmore suggested that the heater power supply was oscillating at the rectifiers.  This makes sense, because it's never "hum" (60 Hz).  It's a 180 Hz artifact that only presented itself when the case is buttoned up.  None of that made sense with typical 60Hz hum.  By default, however, we used very fast Schottky rectifiers for the heater supply and those appear to be causing oscillation.  The noise (as small as it was) has always seemed to favor the left channel, too, which is where the heater supply rectifiers are located.
> 
> Anyway, we went to general purpose diodes and small snubber capacitors for the last couple of kits.  There is really no need for super-speed rectifiers to power just the tube heaters.  The DC requirement is only there to prevent any 60Hz hum, which has never been a problem.  The two Torpedoes that I just built recently used this combination of rectifiers and snubber capacitors and the amp has never sounded better or more quiet.  As I said, I can no longer detect any noise at all with my Grado HF-2's.
> 
> The rectifiers are BY228GP-E3 - Mouser Part #625-BY228GP-E3.  The snubber caps can be numerous possibilities - just look on the Millett MAX, MiniMAX, or MOSFET-MAX BOM's for suggested equivalents.  I used [COLOR=0066CC]SA102A101JAR,[/COLOR] again at Mouser Part #[COLOR=0066CC]581-SA102A101JAR[/COLOR].  All you need do is to solder a snubber cap in parallel across a rectifier.  This is best done on the bottom of the PCB.  Don't solder the snubber caps across two rectifiers, or you'll cause a short - just piggyback each snubber cap across each rectifier.




That sounds quite promising TomB!

Placed my Mouser order earlier today...


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## cubeasic

Hallo,

when will the torpedo kits be available again on beezar? 
Or did I miss them?

Florian


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## tomb

cubeasic said:


> Hallo,
> 
> when will the torpedo kits be available again on beezar?
> Or did I miss them?
> ...


 
 They're only temporarily out of stock.  Edcor is fabricating new transformers, but it may be another week or two.  When I receive them, the Torpedo kits will go right back on sale.


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## Gijs

Hey guys (and gals),
  
 I'm the one who ordered the last Torpedo before Tom ran out of transformers, sorry about that... 
  
 I finished building the Torpedo last Sunday, and spent the last few days building a pupDAC as well. It was my first move into what you would call the "audiophile" world, and for me it was one of those small steps for a man but giant leaps for, err, a man... Until last week I listenend to vinyl, CD's and MP3's through a pair of AKG k271's and k702'd and an Oatley Electronica k272 portable tube amp. Listening to music is different now, to say the least. But, first things first. 
  
 Before ordering both kits, I exchanged some pm's with Tom, asked some "newbie"-questions, and he proved very helpful and patient. For me, it would the first time building both something wall-powered and an  SMD-kit, speaking of challanges... So, I placed my order. The kist came very nicely packaged, everything was clearly marked and explained. Both the BOM's with both kits, as well as the "build-threads" for both kits inspired a lot of confidence. When I had questions, Tom replied within a day. 
  
 Building both kits, different as they may be, was a matter of painting by numbers. The Torpedo kit came with the Zener diodes, the Hammond 154 choke and the snubber caps to put on the recifiers. The latter two were not shown in this build thread, but were well explained on the packaging and on Wikipedia. I also ordered an extra pair of matched tubes, the 5964's. 
 One thing I found: the Torpedo kit it quite sizeable, with a thick PCB and some rather large components. All these drain a  lot of heat from the soldering iron, and I found that my 25 Watt iron could hardly cope. With some components, I really had to take my time and let the heat "sink in", as it were. I did get the job done, but patience was required at times. As for the rest, I just followed this build thread, took my time and all went well. 
 As for the pupDAC, that's the other end of the spectrum. 79 components on a surface the size of a credit card (OK, it's two-sided, but still...)! The first two to fit are the trickiest of the whole kit. I really took my time, and spent about an entire morning just fitting just these first two, always checking a double checking. The pupDAC-site refers to a couple of tutorials on SMD-soldering and, as a noob, I found these very helpful. 
  
 And then there was the glorious moment of plugging in the pupDAC and seeing the LED coming on, then switching on the Torpedo, and seeing its LED's coming on and the tubes beginning to gently glow... I was high on solder flux fumes drunk on enthousiasm! 
  
 Then the journey of re-discovering my entire music collection began. I mainly listen to electronic music, ranging from the older stuff such as Kraftwerk to dubtechno and well produced stuff like the work of someone like Amon Tobin or Kruder & Dorfmeister.  Compared to my previous, now rather rudimentary,  set-up, everything has a lot more presence and detail. I find that the Torpedo does give a lot of detail, especially through the k702's, but presents these details quite gently. These details may not necessarily be found in highs, also mids and lows are presented with a clarity that is at times surprising, even spine-tingling. Also, especially with the k702's, sound stage and headroom are wide, but I haven't found them to be too far off yet (something the k702's are at times been "accused of"). I read on these forums that the k702's lack bass, but I haven't found that to be the case yet, there's also a lot of detail to be found "down below". Everything appears to be presented with "ease". In previous posts in this thread, some people mention the terms "not harsh". I have found this to be a bit of an understatement, I personally would call "musical". Everything I have listened to sofar sounds both precise yet easy on the one hand, but on the other hand, effects such as echo and panning are quite impressive at the same time. 
  
 So much for my endeavours with the pupDAC and the Torpedo. Should you be considering ordering either of the two, I would  say: go for it, they're both worth every penny / cent!


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## tomb

Many, many thanks for such kind comments! 
	

	
	
		
		

		
		
	


	



  
 Just to be clear, though, it's Dsavitsk that's designed the wonderful Torpedo and continues to tweak it for the best performance.  It's really reached a point right now that it's very competitive with amps costing much, much more.  Cobaltmute gave us the pupDAC, a really wonderful USB-powered DAC whose performance is stellar with great midrange and bass, along with outstandingly detailed highs.  It pairs well with the Torpedo (and everything else, too!).  My part is in helping with the prototype builds, documentation, case design - and support when it's not above my head. 
	

	
	
		
		

		
		
	


	



  
 I hope I don't get into trouble with saying this, but I've been quite surprised at the detail that's available through a transformer-coupled tube amp.  I always wondered which was better: good output-coupling capacitors or transformers.  I don't wonder anymore.  If a cymbal crash breaks up, you can rest assured it's in the recording, not the amp or DAC.


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## Punnisher

I agree that it's definitely a world-class amplifier. I have absolutely no desire to upgrade from this. The soundstage has a very spacious and 3D feeling.
  
 It makes my k702 sound brilliant and musical. It does quite well with the HD800 as well, though I didn't have an extended listen with them.
  
 Oh, and I haven't even tried rolling my tubes to the other pairs I have. Just more to look forward to. For the record, my build is stock with 6j6 tubes, though I upgraded to Clarity Caps.


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## bidoux

Hi
  
 I have been looking at the schematic for the Torpedo (quick link : http://www.diyforums.org/Torpedo/schem/TORPEDOschem.gif)  and there are a few things I can't figure out. First is the bias current : is it only 2 or 3 mA ?  Second is the biasing method : does it serve a purpose to have the same current flowing through D12, D13 and D10 (other than saving a few resistors) ? Actually, why the use of a transistor + led under the cathode ? Wouldn't a string of leds or diodes do the same ?
  
 A data I can't find anywhere as well is the B+ voltage. I guess it is in the 200V (and it doesn't matter because of the ccs) but since the bias current seems different than in the other l'espressivo designs ...
  
 thanks


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## dsavitsk

bidoux said:


> Hi
> 
> I have been looking at the schematic for the Torpedo (quick link : http://www.diyforums.org/Torpedo/schem/TORPEDOschem.gif)  and there are a few things I can't figure out. First is the bias current : is it only 2 or 3 mA ?  Second is the biasing method : does it serve a purpose to have the same current flowing through D12, D13 and D10 (other than saving a few resistors) ? Actually, why the use of a transistor + led under the cathode ? Wouldn't a string of leds or diodes do the same ?
> 
> ...




By bias current, you mean the current through the tube, or the current through D12/D13/D10? The former is ~16mA and is set by R4, the latter is 2-3mA and is set more or less by R6 and R7. 

We use the same current as a method of recycling -- ~250V * 3mA is 0.75W. X2 it is the difference between throwing away 1.5W or 3W, which is enough to put significant extra stress on the power transformer, which is heat we don't want to worry about and noise we want to avoid.

The difference between this biasing method and a string of LEDs is that this method is lower impedance and considerably more linear. Keeping this Z low keeps rp lower which helps drive the transformers. And while an LED is an improvement over an RC circuit, this is much better then either.

Yes, B+ is not critical - IIRC it is around 250V, but Tomb probably knows better.


----------



## tomb

dsavitsk said:


> By bias current, you mean the current through the tube, or the current through D12/D13/D10? The former is ~16mA and is set by R4, the latter is 2-3mA and is set more or less by R6 and R7.
> 
> We use the same current as a method of recycling -- ~250V * 3mA is 0.75W. X2 it is the difference between throwing away 1.5W or 3W, which is enough to put significant extra stress on the power transformer, which is heat we don't want to worry about and noise we want to avoid.
> 
> ...


 
  
 To be honest, I haven't measured it while the amp is operating.  Maybe that's something I need to do when I get up enough courage. 
	

	
	
		
		

		
			





  I think you said once, though, that the voltage could go to as high as 275V before everything is loaded up, which is why the caps are rated to 300V minimum.


----------



## bidoux

Thank you both for your answers.
  
 By biasing current I meant the current going through the tube, but I admit that the question was ambiguous. I am still stuck with calculating it ; if I say Vbe of Q3/Q4 is around 0.7V and forward voltage of D12/D13 around 1.8V I get I_bias=(1.8-1.1)/402 since R4/R5 is 402 Ohms. Can't find my mistake here ...
  
 I get your explanation about saving some power on the transformer, I hadn't thought of it and it is as clear as it can be. Actually I was asking since there would be at least two ways of converting the circuit to balanced. Getting inspiration from here (http://www.nutshellhifi.com/preamp-pix.gif) there would be two ways of providing current to the LED. I guess it makes a lot of sense of chosing the one that keeps the electricity bill down 
	

	
	
		
		

		
		
	


	



 (I may have expressed myself very poorly in the last paragraph, it does need a schematic)


----------



## dsavitsk

bidoux said:


> I am still stuck with calculating it ; if I say Vbe of Q3/Q4 is around 0.7V and forward voltage of D12/D13 around 1.8V I get I_bias=(1.8-1.1)/402 since R4/R5 is 402 Ohms. Can't find my mistake here ...




Calculation is correct. What you missed is that we replaced D12 and D14 with a 6.8V Zener. The impedance of the circuit is approximately Hfe1 * Hfe2 * Rbias. By switching to a Zener, we can increase Rbias which increases PSRR considerably, and it makes everything work better. However, we did find that 6.8V was the sweet spot as larger Zeners were too noisy defeating the whole point. With more PCB space, you could put an arbitrarily long string of LEDs, or add a capacitor bypass, but in the limited space we had, this was a good solution.


----------



## dsavitsk

bidoux said:


> Actually I was asking since there would be at least two ways of converting the circuit to balanced. Getting inspiration from here (http://www.nutshellhifi.com/preamp-pix.gif) there would be two ways of providing current to the LED.




Note that with this bias in that balanced configuration, you could push the circuit into class B. You also include the transistor in the signal current loop. Not necessarily bad, but not necessarily what you are after.

If you want to force it to stay in class A, and eliminate the transistor from the signal path, you would use a CCS there. I've done both, and both work well in the right place.


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## bidoux

Cool 
	

	
	
		
		

		
		
	


	




 My preference obviously goes to the string of LEDs, what's not to like about much more lighting ?
  
 I didn't pay attention when I picked the schematic from nutshellhifi. I didn't mean doing someting ultrapathstyle, rather having the primary of the output transformer going from one cathode plate(corrected) to another with the capacitor in the middle (can't find the drawing on the internet edit more or less that : http://www.raleighaudio.com/figure_18.htm).  I am guessing doing this doesn't include the transistor setting the cathode voltage in the signal loop. Does it still change the class of operation from A to AB ?
  
  
 And out of curiosity, do you actually mean replacing the resistor which goes from ground to both cathodes (same drawing : http://www.nutshellhifi.com/preamp-pix.gif) with a current source ? Doing that, how does one makes sure the cathode sits at the right voltage ? Seems like it is going to charge the capacitor which also discharges through the transformer, what is the final state of such a configuration ?


----------



## dsavitsk

bidoux said:


> rather having the primary of the output transformer going from one cathode to another with the capacitor in the middle (can't find the drawing on the internet edit more or less that : http://www.raleighaudio.com/figure_18.htm).  I am guessing doing this doesn't include the transistor setting the cathode voltage in the signal loop. Does it still change the class of operation from A to AB ?




You mean from plate to plate?

On the K&K design, the cap is really there because they are using amorphous core transformers that cannot handle any DC. In fact, if you use too large of a cap, the current just to charge the cap will saturate the transformer which takes some time to recover. With a regular P-P transformer, it is probably not an issue.

That design is always class A, and you probably would not want a CCS in the tail (these are all long tailed pair variations, b/t/w/) as the CCSes would conflict. So you want a resistor there. But you do want it as large as possible (just that a CCS is too large -- though there is some evidence that this may not always be true).




bidoux said:


> And out of curiosity, do you actually mean replacing the resistor which goes from ground to both cathodes (same drawing : http://www.nutshellhifi.com/preamp-pix.gif) with a current source ? Doing that, how does one makes sure the cathode sits at the right voltage ? Seems like it is going to charge the capacitor which also discharges through the transformer, what is the final state of such a configuration ?




Yes, replacing that resistor with a CCS makes it a differential amp. The upside is that performance is better, the downside is that you are limited to class A. The CCS will drop the necessary voltage -- that's how a CCS works. Note that you have to balance the tubes you use with the CCS you use -- some CCSes require more operating voltage than others, so you may need something with very low dropout. That cap is there to shunt distortion away.


----------



## bidoux

Thanks dsavitsk, helps a lot.


----------



## tomb

bidoux said:


> Thanks dsavitsk, helps a lot.


 
 Yeah - glad I didn't have to answer all of that stuff.


----------



## tomb

cubeasic said:


> Hallo,
> 
> when will the torpedo kits be available again on beezar?
> Or did I miss them?
> ...


 
 More transformers have arrived - the Torpedo kits are back in stock!


----------



## tomb

With some helpful suggestions from Jim Cross at vacuumtubesinc.com, we recently discovered *the finest* tube available for the Torpedo: the *E90CC/5920*.  It pushes the amp into an entirely new level of sound quality and performance (IMHO).  A friend at work who has a Torpedo says it sounds like a $1,000 amplifier (not my quote).
  
 Unfortunately, the tubes are somewhat rare and *there is a current non-audio demand for them*: http://www.tnmoc.org/news/notes-museum/valves-attic .  These tubes were originally manufactured for early computers and calculators.  Some machines might use up to 10,000 tubes.  Most of them used 1,000 or more.  Burnouts were also common, one reason they went to solid-state and integrated circuits.  Unfortunately, the National Computer Museum (the link above) and others are using these and similar tubes by the thousands.  Dsavitsk remarked to me: "What a waste of tubes!"  I have to agree.
  
 I'm not normally one to be against preserving fine old equipment - especially ones based in tubes - but these old computers seem a bit ridiculous and are _an actual threat_ to the NOS tube market.  If you have contact with other tube dealers besides Beezar, my personal opinion would be to encourage them not to donate tubes to this museum.
  
 Back to the tube: the data sheet even says it's not recommended for audio (probably a reason the computer museums feel justified in eating them up).  Yet, after using many pairs of these for months in my Torpedo, I'm convinced the only reason for this was to cover the manufacturer against microphonics.  There is more of a tendency toward microphonics than with most tubes, but not by much in my experience.  Microphonics can vary from a slight, quick echo if you tap directly on the tube or amp, or a loud ringing that can last for several minutes.  The latter is tolerable, the former is not.  So, please keep this in mind when purchasing these tubes (from anyone).  The performance gains are worth that much.
  
 A side benefit is that these tubes are so tall that you don't have to remove the Torpedo case lid to swap them out 
	

	
	
		
		

		
		
	


	




:


----------



## H22

*the finest tube available for the Torpedo*

So,.......... What is so great about them? What is it they do that bumps the torpedo to a whole new level? 
Thanks, I am still scraping together funds for one of these amps, hopefully soon....
Thanks TomB!


----------



## Punnisher

I'll have to grab a pair of these. They are somewhat expensive, but definitely not out of reach.
  
 TomB, do you have any recommendations for brand/quantity/origin? There are a fair amount on Ebay. I just want to ensure I get a quality pair that sounds the same between the two.


----------



## tomb

punnisher said:


> I'll have to grab a pair of these. They are somewhat expensive, but definitely not out of reach.
> 
> TomB, do you have any recommendations for brand/quantity/origin? There are a fair amount on Ebay. I just want to ensure I get a quality pair that sounds the same between the two.


 
 My friend at work actually has more diverse experience with them right now than I do.  I've tried Amperex, Phillips and Mullard.  The Mullards might be the most neutral, while the Phillips seem to have a bit of a bass bloom - it's quite nice at lower volumes.  The Amperex were the first I tried and I can't remember whether there were any differences - just that the detail was outstanding compared to a 6J6.  The Telefunkens may have the best quality construction, but I haven't tried a pair yet.  The European-origin E90CC's seem to have tall plates with little tabs that rise out of the top mica spacer, whereas the American tubes have plates that are the height of 6J6 tube plates, but with a getter that's raised on a stilt (necessary to get to the top). I'm not sure yet whether either one means it sounds better, except that all of them are a tremendous improvement over a 6J6.
  
 Some of these are known for having a "pinched waist" where the glass was drawn taller and the diameter shrinks around the center section.  Others have tube tops where the glass is folded on the top with seams (!).  Both are pretty strange attributes.  In my experience with other tubes, however, excellent construction is no guarantee that a tube sounds better.  I've heard RCA's whose construction looked like the mfrs were drunk when they assembled them and they turned out to be among the best in sound quality.
	

	
	
		
		

		
		
	


	



  
  
 EDIT: I may be over-generalizing when referring to European vs American manufacture.  It appears that many European tubes also had short plates, although I haven't seen many long plates on American brands.  There again, there may have been a lot of cross-supplying going on across the pond.


----------



## tomb

h22 said:


> *the finest tube available for the Torpedo*
> 
> So,.......... What is so great about them? What is it they do that bumps the torpedo to a whole new level?
> Thanks, I am still scraping together funds for one of these amps, hopefully soon....
> Thanks TomB!


 
 Quite simply, they are a superior tube - with detail that you'll not hear with a 6J6.  I kept listening for a month or two before I felt like it was safe to talk about these tubes.  My friend at work really helped me in that regard.  He confirmed that everything I was hearing was in fact, true.  I've been fooled before when some opamp or buffer was oscillating and it sounded like the "swishes" were more prominent.  This is something else - detail with great, authoritative bass (the Mullards may have a bit less bass*), and a midrange to die for.  All this without the harshness in complicated passages as might be heard with the 6J6.
  
 Don't get me wrong - the 6J6 is still a great tube when looking at the Torpedo as a mid-fi amp (a very good one).  It's just that the E90CC/5920 pushes the amp into a higher class of transparency and detail.
  
 * Depends on the headphone.  With Grado HF-2 (PS500's) and Sennheiser HD600's, the Mullards sound great.  The Phillips seem to have that extra bass push that really sounds neat with AKG K701's.  You'll notice the leanness again in the K701's with the Mullard E90CC's.


----------



## Punnisher

It's exciting to know that more detail can be had with this amp. Though in stock form it is no slouch.

I have been using the 6j6 from day one and have gotten to know them fairly well. I noticed a clear difference between my Hifimediy 24/96 usb dac and my friend's Esoteric D-07 with the Torpedo and k702. Not exactly a fair dac comparison but it proves the Torpedo is resolving enough to take advantage of great source components. Taking the resolution to another level would be very impressive.


----------



## jdkJake

Had some spare time on my hands today and I installed both the PRR/CCS mod as well as the heater rectifier/snubber mod. Very nice. Very nice indeed. The amp is noticeably quieter.
  
 It is nice to be able to listen to this amp all buttoned up in it's case. Last time I had used it I was running it un-boxed, which, is never recommended at these voltages.
  
 I forgot how good HF-2's sound with this amp. 
	

	
	
		
		

		
			




  
 Placed an order at Beezar for a 5920. Color me intrigued....


----------



## tomb

jdkjake said:


> Had some spare time on my hands today and I installed both the PRR/CCS mod as well as the heater rectifier/snubber mod. Very nice. Very nice indeed. The amp is noticeably quieter.
> 
> It is nice to be able to listen to this amp all buttoned up in it's case. Last time I had used it I was running it un-boxed, which, is never recommended at these voltages.
> 
> ...


 
 Thanks, Jake!  It's nice to have a confirmation that the tweaks definitely make a difference!


----------



## tomb

punnisher said:


> It's exciting to know that more detail can be had with this amp. Though in stock form it is no slouch.
> 
> I have been using the 6j6 from day one and have gotten to know them fairly well. I noticed a clear difference between my Hifimediy 24/96 usb dac and my friend's Esoteric D-07 with the Torpedo and k702. Not exactly a fair dac comparison but it proves the Torpedo is resolving enough to take advantage of great source components. Taking the resolution to another level would be very impressive.


 
 Yes - and thanks!  I've posted this over on the amps section, but I think those guys have incurable FOTM disease:
  
_I always wondered, which sounds better (clearer, more transparent, no veil, etc.)?  Is it an affordable set of output transformers or a good pair of quality coupling capacitors?  Well, I now have no doubt - transformers all the way._
  
 P.S. Dsavitsk has known it for a long time.


----------



## H22

> Quite simply, they are a superior tube - with detail that you'll not hear with a 6J6.  I kept listening for a month or two before I felt like it was safe to talk about these tubes.  My friend at work really helped me in that regard.  He confirmed that everything I was hearing was in fact, true.  I've been fooled before when some opamp or buffer was oscillating and it sounded like the "swishes" were more prominent.  This is something else - detail with great, authoritative bass (the Mullards may have a bit less bass*), and a midrange to die for.  All this without the harshness in complicated passages as might be heard with the 6J6.
> 
> Don't get me wrong - the 6J6 is still a great tube when looking at the Torpedo as a mid-fi amp (a very good one).  It's just that the E90CC/5920 pushes the amp into a higher class of transparency and detail.
> 
> * Depends on the headphone.  With Grado HF-2 (PS500's) and Sennheiser HD600's, the Mullards sound great.  The Phillips seem to have that extra bass push that really sounds neat with AKG K701's.  You'll notice the leanness again in the K701's with the Mullard E90CC's.


 
 Thanks TomB, I am deep in the middle of a B22 build at the moment. The B22 would seem to be a reference for a SS amp, and my current SS amp (PPAv2) is awesome, but I am now craving a great tube amp to compliment my collection. There are a few amps available, but the Torpedo is very appealing. The price is great, and no P2P wiring is awesome for a "pure tube" newb like me.
  
 Hopefully I'll be able to order one soon!


----------



## 00940

A question...
  
 If I'm not mistaken, the Torpedo uses the Edcor PCW10K-7K/300-32, which interests me by itself. The specs on Edcor's website are lacking in details. In particular, did anyone measure DCR of primary et secondary ?


----------



## tomb

00940 said:


> A question...
> 
> If I'm not mistaken, the Torpedo uses the Edcor PCW10K-7K/300-32, which interests me by itself. The specs on Edcor's website are lacking in details. In particular, did anyone measure DCR of primary et secondary ?


 
 Send a PM to dsavitsk.  Edcor made them according to his specs.


----------



## DingoSmuggler

00940 said:


> A question...
> 
> If I'm not mistaken, the Torpedo uses the Edcor PCW10K-7K/300-32, which interests me by itself. The specs on Edcor's website are lacking in details. In particular, did anyone measure DCR of primary et secondary ?


 
 I did measure mine, and if i remember correctly it was 6.7 ohms on the 30 ohm tap, and 23 ohms on the 300 ohm tap, but maybe i'm remembering the incorrect numbers. I can measure again tonight if I remember .
  
 EDIT: i use the word _remember_ way to many times in this post, I'll have to remember not to do that in future


----------



## 00940

I'll pm dsavitsk, thx.
  
 @Dingosmuggler: your memory is probably good... I found a thread where the 6ohms value is given for the 32r secondary, couldn't find anything for the 300R one but 23 sounds very plausible.


----------



## tomb

I'm not close to either of those numbers when I measure one of the OPT's.  However, I'm unsure of myself and the DMM - that's why I suggested PM-ing dsavitsk.


----------



## Punnisher

Here are some pictures related to the Torpedo. They might be interesting to some.
  
  
 Just before upgrading to Clarity Caps.

  
 Testing how the tube guards looked. I ended up using only the top ring for a cleaner look.

  
 Testing my amp/headphones with my friend's source components.

  
 My friend decided to take an artistic picture while I was building my Torpedo.


----------



## tomb

Very nice!


----------



## tomb

I received an e-mail question about the noise fixes/tweaks and I'm concerned that I may have mixed some people up.
  
 Just to be clear, here's the essence of the diode/rectifier and snubber cap tweaks:
  
The BY228GP diode/rectifiers and snubber capacitors are for D5, D6, D7, and D8 – the heater voltage supply. The 1N5062 diodes are in the B+ tube supply and are already high-voltage, general purpose type – no need to change those. I also tried snubber caps across the high-voltage diodes and the noise reduction – if any – was inaudible.  So, the snubber caps have no effect there, either.
  
What is happening to produce the 180Hz ripple noise is that we originally used high-speed Schottky’s  for the heater power supply rectifiers (D5, D6, D7, D8).  As Dsavitsk recommended each of these mods to me, I went from snubber caps only to changing out the rectifiers + snubber caps. I'd say the contribution of each toward reducing the noise is about 50%. IOW, you should do both.
  
  
 P.S. All the kits and built Torpedo's I've sold since first mentioning this have included all of the tweaks.


----------



## jdkJake

I'll second TomBs recommendation, changing out the rectifiers as well as adding the snubber caps makes a significant difference in the noise floor of the amplifier.

Using different rectifiers is a no-brainer. Adding the snubbers is quite straightforward if you attach them to the underside of the board. Wrap each of the snubber cap leads around the leads of the appropriate rectifier (in parallel to the rectifiers) and solder both to the pad at the same time. Think of it as a bypass cap for each of the rectifiers if that helps visualize what you are doing.


----------



## tomb

Thanks for the confirmation, jdkJake!
  
 I hope that post up there looks OK now.  I upgraded to IE V11 a couple of days ago and it's playing havoc with the editing system on Head-Fi. 
	

	
	
		
		

		
		
	


	




  I finally went to Firefox to make the edits, but looks like I messed that up, too.


----------



## Misterrogers

I modded mine last night too. Yep, noise floor is definitely improved. Combined with the tube change, the Torpedo is back in my rotation  This is a special little amp, thanks for continuing to nurture it Tom/Doug.


----------



## tomb

misterrogers said:


> I modded mine last night too. Yep, noise floor is definitely improved. Combined with the tube change, the Torpedo is back in my rotation  This is a special little amp, thanks for continuing to nurture it Tom/Doug.


 
  
 Glad to hear it and thanks!


----------



## Punnisher

Does anyone else have experience with the newly discovered E90CC/5920?

I'd like to know the differences between brands, especially the ones carried by Beezar. I'd prefer the most accuracy across the range. I wouldn't mind a second pair with somewhat lean bass response to help match some of my warmer vintage headphones.

Tomb, feel free to chime in again on this. I'd like a couple opinions before I pull the trigger on a pair or two.


----------



## tomb

punnisher said:


> Does anyone else have experience with the newly discovered E90CC/5920?
> 
> I'd like to know the differences between brands, especially the ones carried by Beezar. I'd prefer the most accuracy across the range. I wouldn't mind a second pair with somewhat lean bass response to help match some of my warmer vintage headphones.
> 
> Tomb, feel free to chime in again on this. I'd like a couple opinions before I pull the trigger on a pair or two.


 

 The Telefunkens I have seem to be a bit lean in bass, whereas the Philips and Amperex seem to have a bit of bass bloom.  I had a few Mullards (no longer) and they were perhaps in-between.  That's the best I can do because at the moment, I'm without a Torpedo.  I sold my own and am in middle of building four more (3 for sale and 1 for me to keep).  I thought I'd have another ready by now with no problem, but it's taking a while with orders and other things in-between.


----------



## cubeasic

punnisher said:


> Here are some pictures related to the Torpedo. They might be interesting to some.
> 
> 
> Just before upgrading to Clarity Caps.


 
 Hallo,
 nice pictures.
  
 So, how did you like the upgrade to clarity caps ESA?


----------



## Punnisher

tomb said:


> The Telefunkens I have seem to be a bit lean in bass, whereas the Philips and Amperex seem to have a bit of bass bloom.  I had a few Mullards (no longer) and they were perhaps in-between.  That's the best I can do because at the moment, I'm without a Torpedo.  I sold my own and am in middle of building four more (3 for sale and 1 for me to keep).  I thought I'd have another ready by now with no problem, but it's taking a while with orders and other things in-between.


 
  
  
 Thanks for the info. Maybe I'll grab some Mullards if they are ever back in stock. For now I'll go with the Telefunken.
  


cubeasic said:


> Hallo,
> nice pictures.
> 
> So, how did you like the upgrade to clarity caps ESA?


 
  
 To be honest it's a very subtle change, and I can't be too sure about the improvements. I'd say a slightly more open sound with a better frequency response. As soon as I turned on the amp with the Clarity Caps I noticed a big difference, though it was very congested and flat sounding. As the caps were used over the next hour or two the sound opened up a lot to where it is now. They definitely do need time to burn in. Not hundreds of hours but at least a few.


----------



## dpump

Did you replace the Solen caps with the Claritys? Or did you have a different cap originally? I have never been a fan of the Solens myself. When I replaced the Solens in my Magnepan 1.6 QR with Audio Caps, there was a big improvement. However, I remember tomb saying he replaced the Solens in his Torpedo and didn't think there was much if any improvement. I think he used the Clarity SAs, which are a step down from the ESAs.


----------



## Punnisher

Yes the original caps I used were Solen. I do believe there is an improvement and would definitely recommended the upgrade. It's just hard to quantify because of the inability to a/b them.


----------



## tomb

Just MHO, and Dsavitsk would need to weigh in on this - but Parafeed caps are not really output coupling caps.  They're more like inter-stage coupling caps, but there's a transformer on the output and it's connected in a special way in a parafeed design.  All of that means the Parafeed caps are not in the same place in the circuit that one would expect in order to detect different effects in sound quality.
  
 IOW, I'm not so sure that differences in film caps really have that much effect in the Torpedo.


----------



## dsavitsk

They are coupling caps, but there is an argument that their inductance interacts with the inductance of the OPT in a way that is different from what would normally happen with a coupling cap. But, if caps make a difference, then his would seem to be a place that they would. I used V-Caps in the L-2 after liking them better than a bunch of others I tried (Mundorfs, etc.) and I definitely thought I could hear a difference.


----------



## tomb

dsavitsk said:


> They are coupling caps, but there is an argument that their inductance interacts with the inductance of the OPT in a way that is different from what would normally happen with a coupling cap. But, if caps make a difference, then his would seem to be a place that they would. I used V-Caps in the L-2 after liking them better than a bunch of others I tried (Mundorfs, etc.) and I definitely thought I could hear a difference.


 

 Maybe the Clarity SA's I used in the past were not any better than the Solens?  The Solens seem to work great for me, but I haven't tried anything as pricy as Mundorfs or V-Caps.
  
 Thanks for weighing in!


----------



## Punnisher

I'm eagerly awaiting my Telefunken E90CC/5920. They should arrive tomorrow. I'll post impressions once I get some listening time in.


----------



## Gijs

First of all the very best wishes for the New Year!
  
 I received my Philips tubes today and have only used them for about two hours now. My Torpedo has the snubber-caps upgrade, as well as the Hammond choke, and use it for my AKG k702's. Compared to the other tubes I've used sofar (6J6, 6J6W and 5964), I agree with TomB's observations that the Philips tubes provide more bass than the other tubes. Bass is far richer, yet remians detailed and fluent. It never gets "boomy" (if that's a word  ). Just what my k702's needed! Also, there's even more detail in the mids than before. I would recommend going for any of these newly discovered tubes!


----------



## tomb

gijs said:


> First of all the very best wishes for the New Year!
> 
> I received my Philips tubes today and have only used them for about two hours now. My Torpedo has the snubber-caps upgrade, as well as the Hammond choke, and use it for my AKG k702's. Compared to the other tubes I've used sofar (6J6, 6J6W and 5964), I agree with TomB's observations that the Philips tubes provide more bass than the other tubes. Bass is far richer, yet remians detailed and fluent. It never gets "boomy" (if that's a word  ). Just what my k702's needed! Also, there's even more detail in the mids than before. I would recommend going for any of these newly discovered tubes!


 

 Wonderful review - thank you!  Yes - just a reminder, but "newly discovered tubes" = 5920/E90CC's. 
	

	
	
		
		

		
		
	


	




 
  
 I got some Q701's over Black Friday and I agree with you - I'm almost not missing listening to my Grados.


----------



## Punnisher

I have received my pair of Telefunken 5920/E90CC. Before I get to my initial impressions I'd like to clarify a few things.
  
 1. I have been listening to my Torpedo with 6J6 since day one. I had a pair of every type of torpedo tube that beezar carried but never felt the urge to remove the 6J6 and try another pair. I liked them that much. They jived incredibly well with my k702 and sr325i, as well as any other analytic/bright headphone. They offered some additional low-end punch, a rich textured midrange and just a hint of natural treble softness that made the k702 _very_ enjoyable and easy to listen to. The Torpedo/6J6 combo is what made me treasure my k702 instead of selling it.
  
 2. I felt that the 6J6 didn't jive quite as well with neutral or warm headphones. This includes my dt880, k240 Sextett, k240 Monitor and k601 which coincidentally are all higher impedance (120ohm-600ohm). These, when paired together, were too warm and lush for my ears. I felt that some detail was being washed out which made the headphones "slow". That is, a loss of texture and some confusion in loud, layered passages of music. I guess you could say there wasn't a tight control of the diaphragm movement.
  
 3. I chose the Telefunken 5920/E90CC after I heard TomB claim the Telefunkens were a bit leaner in the low-end department. I thought this might help compensate for the neutral/warm headphones when being driven by the Torpedo.
  
  
 I swapped out my original 6J6 with the 5920/E90CC and ran some loud music through my k702 for two hours. After listening to a couple of my reference albums I can tell there's a massive difference between these two types of tubes. The first thing I noticed was the overall presentation, in terms of frequency response, was similar to that of a solid-state system with the k702. It was still better than your average solid-state pairing though. There isn't the midrange peak that I couldn't stand with the k702 with solid-state, nor the sharp treble grittiness that made the k702 fatiguing. It was just flat, ultra detailed, smooth but slightly dry. It didn't have quite the bass punch of the 6J6 but in all other respects performed better. It's actually a really good pairing if you're not a basshead. If TomB is right about the other brands of 5920/E90CC having neutral or slightly elevated low-end, they should be a perfect pairing with the k702 and other analytical headphones.
  
 I used the k702 as a baseline to determine the main differences between the tubes, but I didn't buy the Telefunkens for the k702. I started to branch out to my other headphones to see how they fared. I am happy to say my gut feeling was correct, and in fact I underestimated how well the Telefunken 5920/E90CC would work with my other headphones.
  
 I started with the dt880. These fall into the neutral category and were too bassy and lush paired with the 6J6. The Telefunken 5920/E90CC seemed to control the bass a bit better, helped treble extension and dried out the midrange in a good way. It brought the sound spectrum back to a more reference level. I also noticed transients, texture and complex passages were more coherent and controlled.
  
 I finished my night of listening with the k240 Monitor and k240 Sextett MP, both 600ohm. It has become apparent to me that these are extremely hard to drive properly. I don't mean volume, but rather getting any sort of fidelity is difficult due to most amplifiers being underpowered and not voiced for such headphones. Normally, both of these headphones sound underwhelming with a steep treble rolloff and too much midbass. The Telefunken 5920/E90CC definitely improved both of these areas and really surprised me with the result. The bass is extremely controlled where usually it's a loose cannon. It dips low, conveys bass texture well and doesn't have a hump at the midbass. The midrange is about the same, but with slightly more detail evident in vocals, hard vowels, and acoustic instruments. The treble is much improved with better extension, air and spacial details. This is the best and most neutral my k240 Sextett has sounded and I'm quite pleased.


----------



## Misterrogers

I installed a pair of E90CC's bought from Tom about a month ago. At the same time, I changed diodes and added snubbers. I have about 100 hours of playing time with these tubes, and have to day that they've really elevated the Torpedo up a notch. My currently used home/work chains are identical except for a Torpedo at work and a Crack at home. While the Crack slightly edges the Torpedo with E90CC's in sound stage and dynamics, the detail/texture of the Torpedo has me missing it when I'm home. Almost brought it home with me for the holiday break 
  
 For reference, my Crack has Speedball, upgraded caps, and upgraded attenuator.


----------



## tomb

misterrogers said:


> I installed a pair of E90CC's bought from Tom about a month ago. At the same time, I changed diodes and added snubbers. I have about 100 hours of playing time with these tubes, and have to day that they've really elevated the Torpedo up a notch. My currently used home/work chains are identical except for a Torpedo at work and a Crack at home. While the Crack slightly edges the Torpedo with E90CC's in sound stage and dynamics, the detail/texture of the Torpedo has me missing it when I'm home. Almost brought it home with me for the holiday break
> 
> For reference, my Crack has Speedball, upgraded caps, and upgraded attenuator.


 






 
  
 Thanks for the comments!


----------



## Punnisher

Had another audio meet with my friend Tim, and the Torpedo was the focal point. We are both blown away by the sound coming out of the Telefunken E90CC. The midrange and treble are incredibly resolving. Instrument and vocal placement is spot-on. For me, center-mixed vocals are close and intimate and instruments often feel like they're in the room. It also does extraordinarily well with instrument layering and fast textures.
  
 My personal favorite pairing is currently the k601 w/ k702 pads. FYI, I am not affiliated with Beezar in any way, but rather a very excited listener.
  
 Tim took quite a few pictures. Here's a selection:


----------



## tomb

Wow!


----------



## tomb

I added a web page for the 5920/E90CC tubes on the Torpedo website.  It has some good links and all the data sheets I could find on the E90CC.  There's also a bit of information for the E92CC - a similar tube - but it's more like a very-detailed 6J6, not really completely up to the level of the E90CC.  Still, if you can find them, they may be worth a shot.
  
 Everyone who owns a Torpedo should have a pair of the E90CC's, IMHO.


----------



## Punnisher

Thanks for the heads-up. I'll check out that one too.
  
 I was searching a while back and found the radiomuseum.org page for the E90CC: http://www.radiomuseum.org/tubes/tube_e90cc.html
  
 It gives some info in regards to equivalents and similar tubes.
  

*Identical to**E90CC* = CV5214 = 5920*Similar Tubes**Normally replaceable-slightly different:*
  ECC960
  
 Do you have any info on the ECC960 or CV5214?


----------



## tomb

punnisher said:


> Thanks for the heads-up. I'll check out that one too.
> 
> I was searching a while back and found the radiomuseum.org page for the E90CC: http://www.radiomuseum.org/tubes/tube_e90cc.html
> 
> ...


 

 This is what's on ebay right now:
http://www.ebay.com/sch/i.html?_trksid=p3984.m570.l1313.TR0.TRC0.Xecc960+tube&_nkw=ecc960+tube&_sacat=0&_from=R40
  
 It appears to me that the ECC960/CV5214 is a total equivalent to the E90CC, sort of like 6J6 vs 6J6A or 6J6W.  (Maybe it's a Russian/former Eastern Bloc version of the E90CC?)*  That's not all bad, though, because it gives another potential source for tube stock and options.
  
 The thing that made the 5920/E90CC such a discovery is that it and the rest of the tubes above were _not _listed as a functional equivalent to the 6J6 - anywhere.
  
 * Except for two Russian links, my TDSL Personal Edition lists 5920 and E90CC datasheets for the ECC960.


----------



## FishHead

dsavitsk said:


> They are coupling caps, but there is an argument that their inductance interacts with the inductance of the OPT in a way that is different from what would normally happen with a coupling cap. But, if caps make a difference, then his would seem to be a place that they would. I used V-Caps in the L-2 after liking them better than a bunch of others I tried (Mundorfs, etc.) and I definitely thought I could hear a difference.




I am visualizing my build and can only find V-Caps rated at 250V@4.7. Is there something I am missing? 

The other cap candidates are mundorf supremes, obbligato prem gold, and modWright. 

My chain will be Galaxy S3> Fiio E18> torpedo> k701 or s3> torpedo> k701 depending on how the DAC sounds. All recordings are FLAC. Thanks for any help!


----------



## tomb

fishhead said:


> dsavitsk said:
> 
> 
> > They are coupling caps, but there is an argument that their inductance interacts with the inductance of the OPT in a way that is different from what would normally happen with a coupling cap. But, if caps make a difference, then his would seem to be a place that they would. I used V-Caps in the L-2 after liking them better than a bunch of others I tried (Mundorfs, etc.) and I definitely thought I could hear a difference.
> ...


 

 Dsavitsk mentioned his excellent L-2 in that post.  That's a different amp and 250V may have been fine.  The Torpedo needs 300V rated caps at a minimum.  B+ has been measured at over 250V by several builders (I'm too chicken to measure it myself).  There are many others available besides the ones you listed, however.  You can even use a Wima box film cap on the Torpedo, available through Mouser.  Mouser also has a Cornell-Dublier axial film cap that Kevin Gilmore said was a very good capacitor.  Mundorf has many models that will work at all types of prices.  Dsavitsk used an Auricap in his Torpedo prototype.  Many of the early prototypers also used the Mundorf M-Cap MKP - there's one rated for 400V that's only $6.65 from PartsConnexion.  Besides the 4.7uf and 300V minimum rating, just pay special attention to the dimensions and lead spacing available on the Torpedo PCB and you should be fine.


----------



## FishHead

Thanks tomb.


----------



## tdubl07

Hey guys, I just got done building my torpedo and have a few questions. Up until now I've owned nothing but OTL amps. I'm trying out my he-400's right now, (with the telefunken e90's being fed from my modi dac) and this doesn't seem to be working out well. The bass is lacking a great deal compared to my mini max, project ember, and even my starving student build. Is this just how full tube amps are? Also my he-400' start to distort at higher volumes as if there's not enough oomph to drive them (I'm at about 3 oclock on the pot). Something seems off to me with the sound I'm getting. I've went back over any solder joints that looked even remotely suspicious and all look very good. It's dead quiet however, no noise at all which is great, no hums of any sort. Measuring 272VDC at B+. You guys think this amp will pair better with my 990 pro's at work? I'm hoping so and will try out tomorrow. This also has the snubber caps and choke as supplied by Tomb since I just got my kit in. What do you guys say?
 Thanks


----------



## Punnisher

I tried a pair of HE400 with my Torpedo (Telefunken E90CC) and it wasn't a good match in my opinion. It was very warm, lush and didn't seem to extend much into the treble frequencies. This is odd, because every dynamic headphone I try with my amp is hyper-detailed and a bit analytical (the way I like it).
  
 Take it with a grain of salt because the HE400 was defoamed. It sounded neutral with other types of amps, including the SS hybrid.


----------



## tdubl07

punnisher said:


> I tried a pair of HE400 with my Torpedo (Telefunken E90CC) and it wasn't a good match in my opinion. It was very warm, lush and didn't seem to extend much into the treble frequencies. This is odd, because every dynamic headphone I try with my amp is hyper-detailed and a bit analytical (the way I like it).
> 
> Take it with a grain of salt because the HE400 was defoamed. It sounded neutral with other types of amps, including the SS hybrid.


 
 Thanks Punnisher. Does the amp seem like it's powerful enough with everything else? I tried some AD-700's which are insanely easy to drive and still need at least 12 o'clock on the pot to get decent volume. I guess I may have been assuming more power from this build. Just curious. Thoroughly enjoyed the build, I'll wait for my full judgement until tomorrow with my 990's at work.


----------



## Punnisher

The amp has enough power with every dynamic I've ever tried with them. In fact, I'd have to say it's the best amp I've ever heard for any dynamic, ever. I've tried a lot of expensive amps. Keep in mind I'm using the Telefunken E90CC.
  
 You have to take into account the voltage of the input signal, the volume with which you listen, the average volume of the music, and the gain setting of the amp.
  
 I listen at low-medium volume compared to most people. My source is putting out 1.5-2vrms. With the headphones and music I've tried, I usually have the dial around 10-2 o'clock. Maybe lower if the headphones are really efficient. With the HE400 it was 3:00 or more!
  
 I have heard that the amp was designed with a "safe" gain setting that should work with most setups. Perhaps it could be modified to offer some more gain.


----------



## tomb

Yes, Dsavitsk will have to weigh in about gain.
  
 Punnisher is correct when it comes to the standard gain on the Torpedo and the position of the volume pot.  Almost every dynamic works out to about 12 o'clock.  That's one of the beauties of the amp - doesn't matter whether Grado at 32 ohm or Sennheiser HD 580/600/650 at 300 ohms - flip the Z switch and everything is adjusted at 12 o'clock for reasonable listening volume.  The only exception to this that I've found with dynamics is the K701 family - more like 1-2 o'clock for the same volume.
  
 You might try the 6J6 tubes - especially the 6J6W's that I supplied.  Those are among the nicest of the 6J6 family.  The amp definitely sounds better with the E90CC's, but nevertheless, the amp is optimized for the 6J6's.  It's true that the output transformers are going to do all of the converting to voltage and current at the output, so tube selection is not going to affect power that much.  However, the 6J6's may have a bit more punch with the amp (but not the exquisite detail/low distortion of the E90CC's).  Depending on the headphone, that may be a better fit, I don't know.
  
 Max power was estimated by Dsavitsk at about 750mW, I believe.  I would be surprised if some OTL amps exceed that with low-impedance loads, but I suppose if the tubes were very powerful in their own right, it might.


----------



## 00940

> Max power was estimated by Dsavitsk at about 750mW, I believe.  I would be surprised if some OTL amps exceed that with low-impedance loads, but I suppose if the tubes were very powerful in their own right, it might.


 
  
 It's not very difficult to calculate. If B+ is about 275Vdc, Va about 200Vdc and the CCS needs about 10V to operate, max positive swing is 65V. Since the edcor has a 10K-32 ratio, it translates into almost a 18:1 voltage ratio. Hence, into a 32r load, max positive swing is 65/18= 3.6. That's about 2.5Vrms. From there, rms power is about 200mW into 32r.
  
 This doesn't take into account DCR losses, so real max power is more like 180mW.  Which is way more than most OTL into 32R. To put things in perspective, the optimized Morgan Jones is only 10mW into 32r at clipping.
  
  
 edit: silly me... power could be directly calculated from the 65V into 10K... but the result is the same. 
	

	
	
		
		

		
			





 
 edit 2: that's absolute max power. You'd have to actually measure the amp to have the power at 1%thd, which is a common figure to quote the power at. Sims say 20mW (0.8Vrms into 32r) but it's at best a ballpark figure, at worst completely off.


----------



## tomb

00940 said:


> > Max power was estimated by Dsavitsk at about 750mW, I believe.  I would be surprised if some OTL amps exceed that with low-impedance loads, but I suppose if the tubes were very powerful in their own right, it might.
> 
> 
> 
> ...


 

 Thanks for the calculation!  I think my memory betrayed me, big time.  It must've been 250mW that Dsavitsk told me.  He was estimating B+ at the time, though, at about 250-300V, but didn't know exactly where.


----------



## 00940

Yep, with a B+ at 300V, 250mw would make perfect sense. I took the 275V figure from that post.
  
 I might have been rounding some numbers down rather than up too.
  
 edit (again): if someone wanted more power, it could be possible to use the 7K winding rather than the 10K one. You get almost 50% more power that way. It would be ok with the E90CC but not the 6J6, as the E90CC have a much lower anode resistance.
 edit (00940 is a serial editor): going from 200mW to 300mW is in practice negligible. I don't actually advice hacking the board for that; it was just a theoretical remark.


----------



## tomb

serial editors unite!


----------



## tdubl07

Ok guys, just got to work and plugged in my dt-990 pro's. There is no way the sound I'm getting is how it's supposed to sound. I can very easily max out the volume pot and get to barely reasonable levels. Lots of distortion of too. No bass at all. Where shall I begin troubleshooting tonight? Am I correct in saying the output coupling caps are non polarized right? Just the stock Solen's, but there were no markings on them. I'm getting 272V at B+. And the choke is like a resistor correct? So no right or wrong way to put that in (ie backwards). All of my solder joints look real good. It seems like I have something in the wrong spot, or omitted something. All 4 Led's light up from the get go as soon as I turn it on, heaters on the tubes get nice and orange. I am baffled, but there's no way this is what it should sound like. I know that. It sounds really bad. It really feels like I'm trying to drive my phones from an ipod with the current power level I'm getting. Ideas please!? Gotta get this thing dialed in. Thanks
  
 P.S tried all 3 sets of tubes and no difference in behavior


----------



## tomb

tdubl07 said:


> Ok guys, just got to work and plugged in my dt-990 pro's. There is no way the sound I'm getting is how it's supposed to sound. I can very easily max out the volume pot and get to barely reasonable levels. Lots of distortion of too. No bass at all. Where shall I begin troubleshooting tonight? Am I correct in saying the output coupling caps are non polarized right? Just the stock Solen's, but there were no markings on them. I'm getting 272V at B+. And the choke is like a resistor correct? So no right or wrong way to put that in (ie backwards). All of my solder joints look real good. It seems like I have something in the wrong spot, or omitted something. All 4 Led's light up from the get go as soon as I turn it on, heaters on the tubes get nice and orange. I am baffled, but there's no way this is what it should sound like. I know that. It sounds really bad. It really feels like I'm trying to drive my phones from an ipod with the current power level I'm getting. Ideas please!? Gotta get this thing dialed in. Thanks
> 
> P.S tried all 3 sets of tubes and no difference in behavior


 

 Give us some pics - that's the best way for us to check if you missed something.  Meanwhile,
  

Double check all of your resistors
Make certain that you did not install the TO-220 transistors backwards.  Some people have not paid attention to make sure the writing is facing out, not against the heat sink.
Make certain that you have the zener diodes installed correctly.  The black band should be facing the outside solder pad on both the left and right.
  
 Carefully check these things.  The circuit is not really very complicated.


----------



## tdubl07

tomb said:


> Give us some pics - that's the best way for us to check if you missed something.  Meanwhile,
> 
> 
> Double check all of your resistors
> ...


 
 Just double check transistors, all good. I'll get picts up tonight. Thanks Hey Tom I'm rereading your post that says the zener diodes (d11,d12) sould have the black bands facing the outer solder pad. I thought Zeners the black band was the negative side. On both D11,and d12 the outer solder pads are positive on the pcb. If that's the case we have found the problem. I have the black band side soldered to the negative pads (the inner pad)


----------



## tdubl07

Well I think we've found the problem. I've got the zener's in backwards. DOH!!!!! Thanks Tom!!!


----------



## tomb

Just an FYI, but tdubl07 has also been communicating with me via e-mail.  It seems the Zeners were reversed, which would cause all of the symptoms reported.


----------



## tdubl07

tomb said:


> Just an FYI, but tdubl07 has also been communicating with me via e-mail.  It seems the Zeners were reversed, which would cause all of the symptoms reported.


 
 Yep, I knew something was off, becuase man it didn't sound up to snuff. Thanks for the help Tom and everyone else, I will report back as soon as I get these installed properly. Hopefully I don't screw them up desoldering since the leads are mighty short as it stands now. A question though now that we have this figured out. Are the zeners actually installed "backwards" in this circuit since I thought black band was usually negative on zeners?


----------



## tomb

tdubl07 said:


> tomb said:
> 
> 
> > Just an FYI, but tdubl07 has also been communicating with me via e-mail.  It seems the Zeners were reversed, which would cause all of the symptoms reported.
> ...


 

 Yes.  Dsavitsk explained it awhile back in this thread, but I forget the specific reason.  It's why I went to great pains to draw up the detail on the website.  I installed them backwards the first time, too.


----------



## dsavitsk

tdubl07 said:


> Are the zeners actually installed "backwards" in this circuit since I thought black band was usually negative on zeners?




Worth a quick read: http://en.wikipedia.org/wiki/Zener_diode

w/r/t/ power, ideally you might get 200mW from the amp. (The L-2 is more like 250mW.) I'd bet that in practical terms, it is more like half of that. That, however, is plenty of power.

People often misunderstand how much power they actually need to drive headphones. For instance, it is common to see claims that one needs a 10W amp for LCD2s. That 10W amp is usually rated that into 4 Ohms which means that it can swing about 6.5V. That's actually 800mW into the 50 Ohm load of the phones. Into 300 Ohm Sennheisers, it is only 130mW, meaning that this amp has as much power into 300 Ohm phones as a 10W power amp. 

This is a major advantage of properly tapped output transformers in that they preserve power and adjust for voltage and current.

As noted, this amp is not going to drive orthodynamic phones.


----------



## tdubl07

Alright guys got the zener's fixed and this thing sounds awesome. Wish I would have seen the diagram before I put them in, but it was a good learning experience. Ended up soldering them under the board instead as it was far easier with all of the top populated with the heatsinks and wima's. This thing is absolutely dead quiet. No noise at all with no music playing. Just great. Here's a few pics, and I thought I'd throw a pic of the snubber caps installed as well just for reference if it hasn't been shown before, maybe help someone else in a new build visualize them. Thanks!


----------



## tomb

It's wonderful that you got it working - hope you enjoy!
  
 Those are great pics!  I'll use the one for the snubbers, if you don't mind. 
  
 It may take me awhile to properly post it on the website, though.  The US Post Office broke the shipping module on beezar again.


----------



## tdubl07

Yes absolutely use that pic, that's why I put it up. Very glad to have got it sorted out. Fun build and sounds excellent. It will be right at home on my desk at work.


----------



## tdubl07

Hi guys, I've got a slight issue when I first turn on the amp on. This happens with different tubes and tubes swapped from left to right as well. I have a very loud hiss at no volume in only the left channel. It doesn't change with volume or with input disconnected. I've exchanged quite a few emails with Tomb on this and just trying to see some others thoughts as well. The odd thing is, after the amps warmed up a bit the hiss is gone, or at least inaudible to my ears. This morning got it to disappear just by turning the volume pot up to about half volume. At that point the hiss ramped up louder (almost like a crashing wave or inrush of current) and then goes away completely. Once it's gone, I can completely turn the volume all the way back down and it's dead silent. I thought perhaps I overheated the front z switch desoldering it to get it to properly line up with the front panel (since only after I moved it and re-soldered it did I get the noise), so I removed the z switch altogether and added jumpers. That seemed to cure the problem at first attempt. But in the morning here at work the hiss was back. I should also add I trimmed the pot shaft (to get knob closer to amp) with my dremel at the same time I moved the switch. I've ordered new zeners, new switch and all new rectifiers, new led's, transistors and more from mouser just to have on hand to try and get rid of this. Probably be here by this weekend so I can do some troubleshooting. Any ideas gents? Also The amp sounds absolutely fantastic warmed up and with no hiss. I can listen all day and the hiss never returns.


----------



## dsavitsk

That's a new one. Do all of the LEDs light up? What size resistors did you use for R10 and R11, and are C7 and C8 populated?


----------



## tdubl07

dsavitsk said:


> That's a new one. Do all of the LEDs light up? What size resistors did you use for R10 and R11, and are C7 and C8 populated?


 
 Yes all led's light up, first the two, and then all 4 as they should. I got the full kit from beezar so R10 and 11 are 1M, and C7 and C8 are empty and unpopulated. An additon to my prior statement saying the hiss never returns.....it just came back strong in the left channel for a few seconds.....and is now gone again. The amp has been on since I got here to work this morning, so about 5 hrs. I basically reordered all components off of the BOM minus the capacitors to start troubleshooting. Is it possible I overheated the zeners desoldering them when I had them in backwards (or possibly harmed them by having them in reversed) and now one is acting up every so often causing the hiss? It's odd because it's only in the left channel. Dead silent in the right channel all the time. The zener's are gonna be the first thing I change when my mouser order comes in along with my z switch (although I've ruled that out with jumpers in place now). Thanks for the help guys, it's much appreciated.


----------



## dsavitsk

Zener would definitely be the first thing I tried. Let us know.


----------



## tdubl07

Ok a little update. Got my mouser order in. Just put in the new z switch, and also swapped new zeners in, hoping for the best I fired it up and hiss is still there in left channel. All 4 LEDs light up fine, also checked Pl and PR voltages and got 97.2 and 97.9 so I'm guessing those check out fine. Ideas on next thing to swap? Got all new LEDs, all new resistors, transistors, and rectifiers from mouser so what's the most likely thing to be causing the hiss next in line? Forgot to add I do have an extra pot around, I'll probably try that as well. Thanks
Edit, just changed the pot out and so far so good. The hiss is always right when I turn on the amp and it's quiet as of now. It makes some sense to me it could be the pot since I trimmed the pot shaft (dremel), at the same time I moved the zeners and only after did the hiss start in. Fingers crossed that was it.


----------



## tomb

tdubl07 said:


> Ok a little update. Got my mouser order in. Just put in the new z switch, and also swapped new zeners in, hoping for the best I fired it up and hiss is still there in left channel. All 4 LEDs light up fine, also checked Pl and PR voltages and got 97.2 and 97.9 so I'm guessing those check out fine. Ideas on next thing to swap? Got all new LEDs, all new resistors, transistors, and rectifiers from mouser so what's the most likely thing to be causing the hiss next in line? Forgot to add I do have an extra pot around, I'll probably try that as well. Thanks
> Edit, just changed the pot out and so far so good. The hiss is always right when I turn on the amp and it's quiet as of now. It makes some sense to me it could be the pot since I trimmed the pot shaft (dremel), at the same time I moved the zeners and only after did the hiss start in. Fingers crossed that was it.


 

 I'm so sorry you're having trouble like this.  It's hard to see how the volume pot could cause something like this, but if things weren't completely sealed when trimming the shaft, it might have let some metal powder get inside the pot.  Maybe that could cause it.
  
 Just an FYI, and it's my fault for not having this properly documented ... but I don't trim the pot shaft until the amp is built and completely assembled - endplates, all screws, everything - including the shaft washer and nut.  Then I put the amp in a small plastic garbage bag - pot shaft down at the bottom.  I cut a small slice in the bottom and then poke the shaft through (sometimes I cheat and just poke the shaft through the plastic - depends on how thick the bag).  Then I close the bag up in the back with a twist-tie.  A bit of tape on the bag plastic around the shaft threads/nut and things are completely sealed.  Then I dremel about 1/4" off with a cutoff disc(s).  I usually clean up with one of those tips that have a depressed center on top.  It fits right around the tip of the shaft and smooths off the edge.  Then I take the bag off, being careful to go backwards so no metal gets anywhere into the amp.


----------



## tdubl07

Thanks Tom. And no need to apologize, stuff like this happens. No big deal. That's exactly what I did when I trimmed it. I know I did the same thing on my mini max and it didn't cause an issue. Either way it's really the only thing that makes sense since the hissing started after my zener desolder and pot shaft trimmed. Good thing I ordered an extra pot from you a while ago and it's just been sitting in the closet waiting for a project haha. I'll keep u updated.


----------



## tdubl07

OK, well I am absolutely clueless. I did not here a hiss at turn on as usual, and now 10 minutes after my amp has been on, it has made it's unpleasant return. SO I have now changed the pot, changed the zeners, and changed the z switch. What shall I start changing next guys? Like I said I've got all parts in hand except for the capacitors and choke. Is it possible I could have a bad choke? I really am clueless where to start as all my soldering looks great. Transistors next? This is driving me nuts not being able to pin this down! The worst part is how random the hiss is. It still remains only in the left channel. And when it's hissing it's loud enough to hear over the music. The upside to all of this is I'm getting very good at desoldering


----------



## dsavitsk

Weird. I guess I'd do transistors next, and then LEDs.

One thing to think about is that as things heat up, due to expansion, once sound connections can become unsound. So it might be worth re-applying heat to all the joints first.

Choke is probably the least likely candidate on the board.


----------



## tdubl07

dsavitsk said:


> Weird. I guess I'd do transistors next, and then LEDs.
> 
> One thing to think about is that as things heat up, due to expansion, once sound connections can become unsound. So it might be worth re-applying heat to all the joints first.
> 
> Choke is probably the least likely candidate on the board.


 
 OK thanks Doug. I would assume I should only be changing left channel stuff now. I have actually reflowed all joints that look even a little odd but they all look really good. Could this possibly be a bad decoupling/output cap? I have the solen's in right now. If I'm reading the schematic correctly looks like D10,D12 (already changed),D13, Q1,Q3,Q5 will be the next candidates. Also do you guys think it's possible that this could be a bad output transformer on the left channel or highly doubtful?
 Thanks Trav


----------



## tomb

tdubl07 said:


> dsavitsk said:
> 
> 
> > Weird. I guess I'd do transistors next, and then LEDs.
> ...


 

 You've replaced so many parts to no effect, I kind of agree with Dsavitsk: the fact that you didn't notice it until you trimmed the pot shaft may just be a coincidence.  Or, the stress of trimming the shaft may have knocked something loose.
  
 Again, I'm sorry you're going through this, but I would tend to focus on other things besides replacing the parts at this point.  Check all of your resistors - see if you can measure good resistance values by measuring from adjacent pads/traces, not the leads directly.  This can confirm good connections or not.  Also, you might take a close look at the tube sockets - especially on the left side.  I would've said this was a tube thing, but you said you switched them and it stayed in the left channel.  If that's the case, then maybe there's something wrong with the socket on that side and only allows intermittent connectivity with one or more of the pins.
  
 Just some guesses ...


----------



## tdubl07

I am definitely going to have a long hard look at the left tube socket. As you said something might be odd with it. I did manage to break my telefunken in the left tube socket yesterday (cracked it around the pins). Think it was just a coincidence since I have no trouble getting tubes in or out of that socket. Then I shall be off to swapping more parts. Really the only things I've changed so far are the zeners, the pot, and the z switch. It's just been an ongoing battle so it seems like I've changed more. LOL. It's ok, I will get to the bottom of this, just a bit frustrating since I think it's fixed only to come back again. I'll get it fixed guys! There's really not too much to this circuit so not too many parts to go thru. One a time and we'll get to the bottom of it. I will rewet all my joints on the left channel, hopefully tonight, and try again. Thanks


----------



## tomb

tdubl07 said:


> I am definitely going to have a long hard look at the left tube socket. As you said something might be odd with it. I did manage to break my telefunken in the left tube socket yesterday (cracked it around the pins). Think it was just a coincidence since I have no trouble getting tubes in or out of that socket. Then I shall be off to swapping more parts. Really the only things I've changed so far are the zeners, the pot, and the z switch. It's just been an ongoing battle so it seems like I've changed more. LOL. It's ok, I will get to the bottom of this, just a bit frustrating since I think it's fixed only to come back again. I'll get it fixed guys! There's really not too much to this circuit so not too many parts to go thru. One a time and we'll get to the bottom of it. (There something wrong with measuring directly to resistor leads Tom?) I know you can't touch the leads with your hands. Just the probes.


 

 Measuring resistance at the resistor leads does nothing to check whether they're soldered firmly into the circuit board.  Also, when you're measuring resistance and circuit continuity, all power is OFF and the plug is not in the wall socket. 
	

	
	
		
		

		
		
	


	




 
  
 You can do the same thing with the tube socket - stick a probe in each of the holes, then use the other probe to connect to a part/trace somewhere removed from the socket (but supposed to be connected to that pin in the circuit).  If you get zero resistance, then the connection is good.  If not, either you measured the wrong thing or there's a problem.


----------



## lithium1085

Hi everyone,
  
 I have been a lurker on this thread a long time. Do you guys think that someone with no DIY experience (like me) can successfully build this amp? I am very interested in this amp and hopefully can try it soon. Also, what do you guys think about the power output ?


----------



## tomb

lithium1085 said:


> Hi everyone,
> 
> I have been a lurker on this thread a long time. Do you guys think that someone with no DIY experience (like me) can successfully build this amp? I am very interested in this amp and hopefully can try it soon. Also, what do you guys think about the power output ?


 

 As Dsavitsk has confirmed recently, power is on the order of 250mW.  Considering the output transformer ability to switch impedances between high and low, that still works out to enough voltage and current for almost any dynamic headphone - K701/702/712's included.
  
 There are built versions of the Torpedo available at Beezar.  No offense, but I suggest one of those rather than recommending a kit of this amp to someone who has no DIY experience.


----------



## lithium1085

No offense taken....I am realistic about my abilities and it is better to be safe than sorry. I have seen the built versions on Beezar and I was wondering is it possible to order a custom build?
 Basically is it possible to upgrade the capacitors? 
 Do you think 250 mW power is enough for the new generation of planars, which are supposedly more efficient?


----------



## tdubl07

tomb said:


> You've replaced so many parts to no effect, I kind of agree with Dsavitsk: the fact that you didn't notice it until you trimmed the pot shaft may just be a coincidence.  Or, the stress of trimming the shaft may have knocked something loose.
> 
> Again, I'm sorry you're going through this, but I would tend to focus on other things besides replacing the parts at this point.  Check all of your resistors - see if you can measure good resistance values by measuring from adjacent pads/traces, not the leads directly.  This can confirm good connections or not.  Also, you might take a close look at the tube sockets - especially on the left side.  I would've said this was a tube thing, but you said you switched them and it stayed in the left channel.  If that's the case, then maybe there's something wrong with the socket on that side and only allows intermittent connectivity with one or more of the pins.
> 
> Just some guesses ...


 
 Hey guys, got a chance today to a least check resistance values from the left tube socket to adjacent pads and resistors. All tube socket measurements check out at 0hms to adjacent pads and all resistor values check out as well. All continuity checks for left side are good as well. Just learned how to check transistors, so checked all of them, both channels and all test identical to the opposite channel on adjacent pads. So I think all the transistors are ok. At this point, the only thing I can think of doing since all checks lead me to believe everything is fine per specs, is to reflow the entire board and cross my fingers. If that doesn't do it, I'll have to just start replacing stuff one by one. I'm wondering if it's possible to have a noisy resistor that measures good still. That's my next hunch. I can't veify resistance on R10 and R11 since they're grounded. Looked over the entire board with a magnifying glass just to double check my soldering and all looks well.....can't hurt to reflow anyway. The hunt continues....


----------



## tomb

lithium1085 said:


> No offense taken....I am realistic about my abilities and it is better to be safe than sorry. I have seen the built versions on Beezar and I was wondering is it possible to order a custom build?
> Basically is it possible to upgrade the capacitors?
> Do you think 250 mW power is enough for the new generation of planars, which are supposedly more efficient?


 

 Yes, custom builds are possible ... except that a parafeed capacitor is basically the only upgrade that's readily available.  It's simple enough to substitute another type/brand of capacitor into an already built Torpedo, though.  And yes - I can do that for you, too.
  
 I can't speak about the new generation of planars, except to say that if they're similar to a K701 (normally considered among the hardest to drive dynamics), then it should do fine.


----------



## tdubl07

I think I've found the problem guys!!! I reflowed the whole board and that didn't fix it. So I left the case open and took a pencil and used the eraser to start tapping on things. Got to D10 the front led (which was lit) tapped on it, and got a loud pop...and along with the pop the hiss would appear! Just desoldered the old led from d10 and replaced it. I'm hopeful that was the problem. I can not believe that an led could light up and still be "bad" in the circuit for it's intended purpose. I should have used the eraser trick much earlier.
 Time to rock out


----------



## tdubl07

lithium1085 said:


> No offense taken....I am realistic about my abilities and it is better to be safe than sorry. I have seen the built versions on Beezar and I was wondering is it possible to order a custom build?
> Basically is it possible to upgrade the capacitors?
> Do you think 250 mW power is enough for the new generation of planars, which are supposedly more efficient?


 
 Hey man, just thought I'd throw this in. Listening to my HE-400's right now with this amp and it's drives them just fine. And that's with my phone straight to the amp. With a dac, it's even better in terms of power output since the dac puts out a stronger line signal than a phone. I think I like my dt990 pro's better with this amp but that's just preference, nothing more. As has been said before but if the phones you're looking at are terribly innefficient I think you should look elsewhere. Plenty of juice though for my dt 990 pro's and he-400's.


----------



## tdubl07

Well guys, she's fixed! I can't believe a working led (lit up) could cause all of my problems. Glad to have this thing dialed in now. Thanks for everyone's help


----------



## Punnisher

I'm glad to see it worked out for you. I feel your pain, because I wouldn't ever want to be without a working Torpedo.


----------



## lithium1085

Thanks for the input everyone. I guess I will scrounge up some cash in the next few months and get tomb's completely built version. I am not planning on driving something much more inefficient than the HE-400, so the power output is perfect.


----------



## dsavitsk

lithium1085 said:


> No offense taken....I am realistic about my abilities and it is better to be safe than sorry. I have seen the built versions on Beezar and I was wondering is it possible to order a custom build?
> Basically is it possible to upgrade the capacitors?
> Do you think 250 mW power is enough for the new generation of planars, which are supposedly more efficient?




I actually don't think it is too difficult as a first build if you know something about electricity, and if you have someone who knows how to solder sit next to you and guide you through the process. Indeed, for anyone for whom this is his first high voltage process, that is probably a good idea.

As to the parafeed caps, I would not worry too much about it. Better caps might make a small difference, but I think you'll be surprised about the sound quality in stock form. Most top of the line commercial equipment uses similar quality parts.


----------



## lithium1085

dsavitsk said:


> I actually don't think it is too difficult as a first build if you know something about electricity, and if you have someone who knows how to solder sit next to you and guide you through the process. Indeed, for anyone for whom this is his first high voltage process, that is probably a good idea.
> 
> As to the parafeed caps, I would not worry too much about it. Better caps might make a small difference, but I think you'll be surprised about the sound quality in stock form. Most top of the line commercial equipment uses similar quality parts.


 
 Thank you for your input. I am guessing I will buy this in a few months, so maybe I can try to learn how to solder by then.


----------



## AnalogSavior

Hi all,
  
 I'm pretty new to DIY with only a little bit of guitar pickup rewiring  under my belt, but after reading the article on parafeed amps on the ecp diy site, I'm curious to build one.  I don't have a background in electronics, so I don't understand everything going on, but I learned quite a bit from it and my math for the hypotheticals provided all added up.  I'm curious to try new things amp wise, so this seemed like the perfect project for me.
  
 I really don't have anyone with experience to help me along, but do you think that with some patience and care a relative noob like myself could tackle this project?
  
 Also, I read the Headfonia article on the Torpedo, and it mentions a small transformer hum.  It wont play a role in whether I take on the project or not, but I'm curious if this is a common thing and if it is easily resolved.  The Zener Diode tweak mentions that it can reduce hum, and I'm just curious as to what to expect.
  
 Thanks!
  
 EDIT: After reading the tweaks and beezar pages again, it looks like the zener mod and choke replacing R2 are standard.


----------



## tomb

analogsavior said:


> Hi all,
> 
> I'm pretty new to DIY with only a little bit of guitar pickup rewiring  under my belt, but after reading the article on parafeed amps on the ecp diy site, I'm curious to build one.  I don't have a background in electronics, so I don't understand everything going on, but I learned quite a bit from it and my math for the hypotheticals provided all added up.  I'm curious to try new things amp wise, so this seemed like the perfect project for me.
> 
> ...


 

 There were really four tweaks that solved the hum problem:

Use of the choke
Zener diode tweak
Replacing the heater supply schottky rectifiers with general purpose diodes.
Installing snubber caps on the diodes in #3 above.
  
 The last two were the latest and solved the hum issue from all reports.


----------



## tomb

We're now shipping with a V1.02 PCB that Dsavitsk designed.  Changes are as follows:

Trace moved under the PCB that was impinging on one of the standoffs
Allowance for zener tweak with normal through-hole mounting.
SMD pads on the bottom of the PCB for snubber caps on the heater rectifier (general purpose diodes).
  
 Of course, because it's NEW ... that means it sounds better.  Just kidding.


----------



## ChrisX

tomb said:


> We're now shipping with a V1.02 PCB that Dsavitsk designed.  Changes are as follows:
> [...]SMD pads on the bottom of the PCB for snubber caps on the heater rectifier (general purpose diodes).


 
  
 I just picked up my kit from customs on Friday ... and have already the new PCB included. 
	

	
	
		
		

		
		
	


	



  
 So which SMD caps do you recommend?


----------



## AnalogSavior

tomb said:


> There were really four tweaks that solved the hum problem:
> 
> Use of the choke
> Zener diode tweak
> ...


 
  


tomb said:


> We're now shipping with a V1.02 PCB that Dsavitsk designed.  Changes are as follows:
> 
> Trace moved under the PCB that was impinging on one of the standoffs
> Allowance for zener tweak with normal through-hole mounting.
> SMD pads on the bottom of the PCB for snubber caps on the heater rectifier (general purpose diodes).


 
  
 Wow, thanks for the great information.  A few more questions if you don't mind.  How many of these tweaks are included in a complete kit (I'm pretty sure I read the Zener diode and a Hammond choke are part of it)?  Regarding the scope of the project, aside from the SMD pads for the snubber caps, is the rest of the project through hole?
  
 This seems like an exciting project for me, but I may need to tackle a smaller one or two (maybe a CMoy or Mini3) before I take it on, just to feel a little more comfortable.


----------



## tomb

analogsavior said:


> tomb said:
> 
> 
> > There were really four tweaks that solved the hum problem:
> ...


 

*All of the tweaks are included in the kit.*  The new PCB recognizes this by incorporating all of them.  I'm not sure why there would be a question of doing otherwise if it makes the amp better, but maybe making that strong statement will make it clear.
	

	
	
		
		

		
			




  
 The SMD for the snubber caps are trivial.  You can still solder leaded axial capacitors across the diode leads instead, if you wish - making it 100% through-hole.  If you haven't soldered parallel leaded parts before, trust me when I say the SMD capacitors are much simpler.  They're large pads, so 1206 SMD will easily work - or smaller, if you desire.  I'll spec some parts shortly and update the BOM when I get a chance.  For now, I've been including the leaded snubber caps in the kits.


----------



## AnalogSavior

tomb said:


> *All of the tweaks are included in the kit.*  The new PCB recognizes this by incorporating all of them.  I'm not sure why there would be a question of doing otherwise if it makes the amp better, but maybe making that strong statement will make it clear.
> 
> 
> 
> ...


 
  
 Ha! I guess I was over thinking it a bit, but still thanks for the answer.  You strong statement has indeed put me at ease.


----------



## dpump

Wanted to post some comments about my experience with the Torpedo amps. I had one of the earlier amps with the Schottky diodes and no snubber caps. I did make the diode mod and replace the resistor with the choke. This amp, as has been stated by other users many times before, did have an audible hum on all phones. This is the hum that TomB and Dsavitsk struggled to eliminate, along with other builders who tried all sorts of shielding schemes. Nothing really seemed to work, so I ended up selling this amp.
  
 When I read about the fix for the hum-using general purpose diodes and snubber caps-along with the discovery of the E90CC tubes, I knew I had to have another Torpedo. I had loved the sound of my first amp, just not the background hum. So, last December I ordered and built the newest kit and bought some E90CC tubes. Now I have the Torpedo 'sound' back, but even better. There is now either no hum or a very, very small amount of hum with all the phones I have tried. The only phone that I even really notice any hum on is the Beyer T90, and that is due to the high efficiency of that phone. There is a barely audible hum with the Sennheiser HD-800, but nowhere close to being audible if any music is playing. (Yes TomB, the new Torpedo is beautiful with the HD-800 with Charleston Cable Companies' top cable. The Torpedo is that good). Keep in mind that almost all tube amps have some background hum and/or noise-it's the nature of the beast. The new Torpedo is as good as, if not better than, most other tube amps in this regard. And as TomB has said, the E90CC tube takes the Torpedo to an even higher level than the 6J6 tube.
  
 If you are thinking about buying a Torpedo but you're not sure you will like it, I can only say do not hesitate. The sound is sublime. It's like relaxing with your feet up with your favorite pair of well broken in slippers. The sound is so smooth and mellow but also very detailed without being 'in your face'.


----------



## AnalogSavior

Thank you very much for your impressions! I'm pretty much decided on taking on the project, and was more looking into what to expect when I asked about the hum.  All the info I have gotten has been great. 
  
 As soon as I have some time to put one together, I will definitely be ordering one,


----------



## Punnisher

I agree that the E90CC has reduced the hum to a nearly inaudible level. Any background noise in your natural environment will almost certainly be louder than the hum.
  
 I still say that the Torpedo is one of the best amps (if not the best) I've ever tried, especially with dynamic headphones. You can't go wrong.


----------



## dpump

punnisher said:


> I agree that the E90CC has reduced the hum to a nearly inaudible level. Any background noise in your natural environment will almost certainly be louder than the hum.
> 
> I still say that the Torpedo is one of the best amps (if not the best) I've ever tried, especially with dynamic headphones. You can't go wrong.


 

 To be accurate, it isn't the E90CC tubes that reduced the hum. It is the replacement of the original Schottky heater diodes with general purpose diodes with a shunt capacitor across each diode. Anyone who has an older amp can do this mod to reduce hum, along with the diode mod.
  
 When I built my current Torpedo amp I used ClarityCap SA coupling caps. Last week I replaced the SA's with ClarityCaps top of the line MR's. There was an obvious change for the better with a noticeable improvement in detail and a more top end. I had read reviews about ClarityCaps saying that the SA and SE were warmer sounding than the MR, and now I believe it. It's an expensive upgrade but I feel well worth it.


----------



## Punnisher

I noticed a large reduction of the volume of hum when I installed the E90CC over the stock 6J6. I can test it again to confirm but it was noticeable.


----------



## tomb

Yep. It's quite possible that a tube change can be responsible for _a reduction in noise_.
  
 The E90CC is inherently a much, much quieter tube that runs at lower distortion. It also runs at a lower current than the 6J6 tube family.  This may put less stress on the power transformer and surrounding circuit, potentially reducing noise even further.   There are 6J6 tubes that are greater offenders than others, though, so the differences might be more severe in some instances.  I would agree that the primary noise reductions have been through the tweaks that we implemented.
  
 That said, the amp simply sounds better in every way with an E90CC.  Noise reduction would be part of that equation, regardless of the specific cause.
  
 I guess I'm agreeing with you both, if that's acceptable.


----------



## ChrisX

I just finished assembling my Torpedo PCB. At first startup I have seen that the DC voltage at C11/C12 varies between 130 V at one channel and 145 V at the other channel. After exchanging the tubes the voltages followed with the tubes. Would this measurement be a good indicator for tube matching or is this voltage reading unimportant?


----------



## dpump

Here are pictures of my Torpedo with the ClarityCap MR 4.7 mFd capacitors I recently installed.


----------



## jboehle

You should install parts with the printed values facing up, so when someone has to repair / mod it in the future, it's easy to see what's what.


----------



## dpump

jboehle said:


> You should install parts with the printed values facing up, so when someone has to repair / mod it in the future, it's easy to see what's what.


 
 I agree. However, the leads were already bent from the factory and I didn't want to twist them around to keep from fatiguing the metal. I read of one person who did that and one of the leads broke off. Didn't want to take a chance on that.


----------



## tomb

dpump said:


> jboehle said:
> 
> 
> > You should install parts with the printed values facing up, so when someone has to repair / mod it in the future, it's easy to see what's what.
> ...


 

 I normally always recommend the same thing, but with parts that big - I don't think it matters.  One other thing to consider - even more important - is that you can ruin a film cap like these if you try to rotate already bent leads to get the labeling to face up.  It's possible to torque the leads right out of the film capacitor spiral inside, effectively ruining the film cap.
  
 Here's what one looks like on the inside:


 The leads are soldered directly the foil/dielectric roll.


----------



## tomb

chrisx said:


> I just finished assembling my Torpedo PCB. At first startup I have seen that the DC voltage at C11/C12 varies between 130 V at one channel and 145 V at the other channel. After exchanging the tubes the voltages followed with the tubes. Would this measurement be a good indicator for tube matching or is this voltage reading unimportant?


 

 Dsavitsk would have to answer that, but my guess is yes.  If they're my tubes, please let me know and I'll replace them with something better matched.


----------



## dsavitsk

dpump said:


> To be accurate, it isn't the E90CC tubes that reduced the hum. It is the replacement of the original Schottky heater diodes ...




With the E90CC the heater draw is lower which puts less stress on the power transformer which then emits less noise. But you are right that the different diodes matter, too.




chrisx said:


> I just finished assembling my Torpedo PCB. At first startup I have seen that the DC voltage at C11/C12 varies between 130 V at one channel and 145 V at the other channel. After exchanging the tubes the voltages followed with the tubes. Would this measurement be a good indicator for tube matching or is this voltage reading unimportant?




We tend to use DC matching as a proxy for AC matching, but who knows whether this is a reasonable thing to do for any given tube. The easiest way to check yours would be to play a 60Hz tone and measure the AC output from both channels with a multimeter (even cheap meters can measure 60Hz reasonably accurately.) That should give you an idea how mismatched your tubes are. And truth be told, tube matching is not that important here. They'd have to be way way off be before you'd hear much of a difference.





dpump said:


> I agree. However, the leads were already bent from the factory and I didn't want to twist them around to keep from fatiguing the metal. I read of one person who did that and one of the leads broke off. Didn't want to take a chance on that.




I ripped a lead out of an Auricap once doing that.


----------



## ChrisX

tomb said:


> Dsavitsk would have to answer that, but my guess is yes.  If they're my tubes, please let me know and I'll replace them with something better matched.


 
  
 That was one pair of the kit indeed. Thanks for the offer but I plan to use the 6J6 only for initial setup and I'm going to switch to E90CC anyway, so the tubes are ok for me.
  


dsavitsk said:


> We tend to use DC matching as a proxy for AC matching, but who knows whether this is a reasonable thing to do for any given tube. The easiest way to check yours would be to play a 60Hz tone and measure the AC output from both channels with a multimeter (even cheap meters can measure 60Hz reasonably accurately.) That should give you an idea how mismatched your tubes are. And truth be told, tube matching is not that important here. They'd have to be way way off be before you'd hear much of a difference..


 
  
 Thanks for the idea about AC matching. I will try to match the best pair of my 5-pack of E90CC this way. I assume that this will give more useful results than matching with my very simple Sencore tester. I have access to a good multimeter so maybe I can also measure at higher frequencies. But first I will make the proposed measurement with the 6J6 mentioned above to get a feeling about the relation between DC and AC mismatch.


----------



## dpump

Since some of you report that E90CC tubes should be quieter than 6J6 tubes, I decided to do a comparison. In my new Torpedo I had only used Philips and Telefunken E90CC. Although I have a number of different 6J6 from the older Torpedo I used to have, which I sold before the E90CC was discovered, I tried the Sonotone 6J6 in my new Torpedo.
  
 I could tell no difference in the slight hum I hear with the Sennheiser HD 800-both the Sonotone 6J6 and the Telefunken had the same amount of hum. There was some difference in sound between the tubes. The Sonotone had a little more bass-it was warmer and more rounded in the bass. As far as the midrange, there was very little difference, with the Telefunken having a little more detail. The highend was a little more prominent on the Telefunken, but this was probably because of the lighter bass response. I still prefer the Telefunken as it seems to be a little quicker, but the Sonotone was surprisingly good. The Sonotone was mentioned a while back, I think in this thread, as being a favorite of several people. The guy I sold my older Torpedo to also prefered it. I could be happy with the Sonotone if the E90CC wasn't available.
  
 Maybe putting the E90CC in an older Torpedo without the diode/snubber cap/choke/diode updates would result in lower noise. In my new Torpedo I heard no noise difference. As Tomb has said, the E90CC is generally a more microphonic tube than the E90CC. The Telefunkens in my amp are pretty microphonic-plugging or unplugging phones or contact with the case will cause ringing that takes a few seconds to subside. Not really a problem when listening, but more microphonic than most 6J6 tubes. As TomB said, the E90CC wasn't designed to be an audio tube. Just my 2-cents-YMMV.


----------



## tomb

dpump said:


> Since some of you report that E90CC tubes should be quieter than 6J6 tubes, I decided to do a comparison. In my new Torpedo I had only used Philips and Telefunken E90CC. Although I have a number of different 6J6 from the older Torpedo I used to have, which I sold before the E90CC was discovered, I tried the Sonotone 6J6 in my new Torpedo.
> 
> I could tell no difference in the slight hum I hear with the Sennheiser HD 800-both the Sonotone 6J6 and the Telefunken had the same amount of hum. There was some difference in sound between the tubes. The Sonotone had a little more bass-it was warmer and more rounded in the bass. As far as the midrange, there was very little difference, with the Telefunken having a little more detail. The highend was a little more prominent on the Telefunken, but this was probably because of the lighter bass response. I still prefer the Telefunken as it seems to be a little quicker, but the Sonotone was surprisingly good. The Sonotone was mentioned a while back, I think in this thread, as being a favorite of several people. The guy I sold my older Torpedo to also prefered it. I could be happy with the Sonotone if the E90CC wasn't available.
> 
> Maybe putting the E90CC in an older Torpedo without the diode/snubber cap/choke/diode updates would result in lower noise. In my new Torpedo I heard no noise difference. As Tomb has said, the E90CC is generally a more microphonic tube than the E90CC. The Telefunkens in my amp are pretty microphonic-plugging or unplugging phones or contact with the case will cause ringing that takes a few seconds to subside. Not really a problem when listening, but more microphonic than most 6J6 tubes. As TomB said, the E90CC wasn't designed to be an audio tube. Just my 2-cents-YMMV.


 

 Many thanks for your impressions!
  
 Yes, the Sonotone is a fine example of the 6J6.  There are others - the USN JAN comes to mind.  That said, I guess we'll have to agree to disagree.  IMHO, the E90CC is significantly superior - as you say, more high-end detail and definitely quicker.  Also, I suspect that the extra bass you're hearing in the Sonotone maybe emphasized by greater noise.*
  
 It may still depend on the headphone, too.  I have been tracking the noise for several years now, and know exactly where and how to hear for it.  I don't have HD800's, but with E90CC's I cannot hear the noise with any of my phones (HD600's, HF-2's, etc.).  If you use a PC as your music file source (many of us seem to do that these days), this can affect the Torpedo if it's too close.  At my previous residence, I think I had the Torpedo way too close to the PC.  I could barely detect the noise with some headphones, even using the E90CC - but I can't at my new residence.  I know from previous experience that the Torpedo can easily pick up transformer flux from adjacent devices and resonate with increased noise: other stereo equipment with transformers, wireless phones, wireless cable router, etc. - the PT in the Torpedo will pick them all up if it's too close.  A good separation distance and the use of all of the tweaks + E90CC tubes should reduce any noise to zero in most cases.  The HD800 may be different, though.
  
 * I prefer to use the term "ripple" or "noise" to describe the sound when it was easily heard in the past (pre-tweaks and E90CC's).  "Hum" almost always refers to 60Hz line frequency noise caused by poor transformer application or other power-related issues.  That was never an issue with the Torpedo - it was at 180Hz, and we suspect was caused from oscillation of the heater rectifiers and was magnified by their proximity to the power transformer.  That's why one of the major tweaks incorporated general purpose diodes instead of the super-fast-switching Schottky's that were originally used.  The addition of the snubber caps also help to fight any oscillation that might be produced.  As Dsavitsk immediately realized when KG suggested this cause, there is no reason at all to use high-performance rectifiers just to power the tube heaters.


----------



## OJNeg

Okay, just ordered the Torpedo kit + some extra goodies. Excited to get soldering!


----------



## ChrisX

chrisx said:


> Thanks for the idea about AC matching. I will try to match the best pair of my 5-pack of E90CC this way. I assume that this will give more useful results than matching with my very simple Sencore tester. I have access to a good multimeter so maybe I can also measure at higher frequencies. But first I will make the proposed measurement with the 6J6 mentioned above to get a feeling about the relation between DC and AC mismatch.


 
  
 I have finished the Torpedo build today. As said before I first measured the slightly mismatched 6J6 by looking at the output. Test setup was output switch set to high, 330 Ohm load resistance. As mentioned before, the DC voltage at C11/C12 was 128 V at the left, 144 V at the right channel. With a 2 Vpp sine wave at the inputs and the pot full open I measured 2.82 V left/2.99 V right ACrms at 50 Hz, 2.90 V/3.07 V at 500 Hz and 2.33 V/2.5 V at 5 kHz (the scope confirms the slight differences) which results in a channel imbalance of about 0.4 - 0.5 dB, so as Dsavitsk stated before not much to worry about.
  
 Kudos to the Telefunken E90CC. I have bought a NOS 5-pack of these tubes, the first two I picked showed 101 (whatever, maybe percent) on my Sencore tester on all 4 systems, so I didn't even check the remaining 3 tubes. These two tubes in the Torpedo show both 105 V DC at C11/C12, AC output shows 2.39 V/2.39 V (50 Hz), 2.42 V/2.42 V (500 Hz), 2.44 V/2.43 V (5 kHz). So they match perfectly. Furthermore these pair of tubes shows no microphonics, while one of the 6J6 (JHS Sylvania) did.
  
 These results show that DC matching is valid for a good AC match in this setup.
  
 The amp is totally quiet, for initial listening I used my 600 Ohm AKG K240. I was really satisfied with the sound, only drawback is that the gain of the amp is just sufficient with these headphones (listening position of the pot between 3 and 4 o'clock), but as seen above the E90CC is slightly less efficient than the 6J6. I didn't test with other cans yet (and unfortunately also won't be able to do so in the next days).
  
 BTW: Maybe this is the first Torpedo running with SMD caps? I used Kemet 500 V C0G 1206 types.
  
 .


----------



## FishHead

Ordered a Torpedo for when I get back to the States. Since I could not decide on a cap I ended up buying a variety:rolleyes:. While researching them there was some discussion (vcap) on how the cap should be oriented. Ie the outermost foil connection should be connected to B+. Does this recommendation apply to a parafeed design? Which way is B+?


----------



## tomb

fishhead said:


> Ordered a Torpedo for when I get back to the States. Since I could not decide on a cap I ended up buying a variety:rolleyes:. While researching them there was some discussion (vcap) on how the cap should be oriented. Ie the outermost foil connection should be connected to B+. Does this recommendation apply to a parafeed design? Which way is B+?


 

 B+ is the opposite direction of the output transformers and headphone jack.


----------



## FishHead

Thank you very much. I will post my impressions on the caps over time once I am up and running. Would you like to keep the content here or start a Torpedo Cap rolling thread? I have seen cap threads get a little crazy. Not that tHose who build Torpedos are anything but very sane pedestrian sort of people.


----------



## tomb

fishhead said:


> Thank you very much. I will post my impressions on the caps over time once I am up and running. Would you like to keep the content here or start a Torpedo Cap rolling thread? I have seen cap threads get a little crazy. Not that tose who build Torpedos are anything but very sane pedestrian sort of people.


 
 JMHO, but I'd prefer to keep it sane and somewhat pedestrian.


----------



## OJNeg

Ok then...I've spent the last month enjoying this amplifier immensely. Construction was a cinch for me. And it's absolutely gorgeous sitting on my desk (w/ no top cover 
	

	
	
		
		

		
		
	


	




)
  
 I ordered 5 pairs of tubes from Beezar with my kit. 6J6A (Japan, UFO), 6J6W (RCA, Mid Sq), 5844 (GE), 5964 (GE, Top Halo), and the E90CC (Telefunken). I just read through the entirety of this thread and I'm surprised with how well my own impressions of the different devices match with others'. Specifically TomB's post back on page 5. From my own notes:
  
 'Phones: Senn HD600, Ety ER4S
 D/A: AMB gamma2
 Other amplification: AMB CKKIII
  
*6J6A: *

Definitely the most dynamic tube of the bunch. Can swing high and low without compression in either direction
Guitars are very engaging without being overly aggressive
Very top end is a bit less present, can seem dull with certain instruments
Instruments have a great fluid quality, but vocals seem to be lacking the last bit of clarity I'm used to
Soundstage is well differentiated but not what I would consider "expansive"
Very natural and organic timbre with things like hand claps, also more 3D spatially
_Comments_: Very good. Easy to listen to and engaging. Things are looking good for this amp.
 *5844:*

Kinda boring sounding
Less detailed, less fluid
Bit grainy?
_Comments_: Not impressed, what I would consider a downgrade from the 6J6A. TomB mentioned this one had a "exaggerated midrange", but I hear it just as poor sounding and lacking extension in both directions. This tube kinda sounds like what the others tubes sound like when they're not warmed up yet. I keep waiting for this tube to kick into gear, but it still sounds unrefined regardless. Didn't end up spending much time with this little guy.
 *5964*

More similar to 6J6A than 5844
More spacious and longer decay than 6J6
Bit softer and less dynamic than 6J6
I feel the bass on the 6J6 is more dynamic, solid, and better differentiated (in terms of pitch)
_Comments_: A valid sidegrade to the 6J6A I suppose. While it ups the fluidity of the amp, it does take away a certain level of microdetail and sharpness in return for a more diffuse presentation. I spent a lot less time with the 5964 than the 6J6A, which says something I guess
 *E90CC*

Oh snap! Leagues different than any I've tried so far. More forward presentation and more microdetail!
This tube does a better job of letting the music portray it's own character rather than impart its own. It simply lets the pacing/atmosphere/emotion through better. I know that sounds like BS and you're probably rolling your eyes, but that's just the best way I can put it. You could say that this device is less colored than the others in a sense.
More analytical with regard to electric guitars (6J6A preferred to be fluid)
This device seems like it's faster at tracking the input signal and recovering information in the treble. Even compared to solid-state amps
_Comments_: This tube is definitely on a different level compared to its smaller brethren, as TomB said. It takes the technicalities of this amp up a few notches. You could say it's a bit leaner sounding in the bass and mids (than the 6J6A), but it's not really brighter or anything. Meaning, it's not increasing gross detail by boosting the treble, it's just inherently more detailed it's own. The only concrete drawback of this device would be that I feel it renders a slightly artificial texture compared to the 6J6A. This is outside of the lean-ness or increased detail, it's just that instruments sound less organic and natural in terms of texture (not timbre, if that makes any sense). A small niggle that I noticed.
  
 Overall, this amp holds its own against my CKK. It is a touch warmer than the CKK throughout the the spectrum (regardless of tube choice) and has less top-end presense, but this is definitely not an uber-tubey, syrupy, drown-in-warmth sort of valve amp. It's accurate and balanced, while delivering big images and digging deep into the music. It has absolutely zero harshness in itself, but will render it if it's on the recording. At this point, the E90CC's get most of my listening time, but I'll put in the 6J6A's if I want to rock out to some metal and crank the volume.
  
 I have yet to try the 6J6W but I'd suspect them to be fairly similar to the 6J6A's. I also have a pair of Jantzen CrossCaps on the way so we'll see if those make any tangible difference for me. Might also try the Mundorfs or ClarityCaps eventually.
  
 Big thanks to TomB and Doug for making this amp available!


----------



## tomb

Many thanks for that fine review!


----------



## FishHead

I thought I would post some build impressions for V 1.02. I brought the project over to Dubai as something to do when it is 105 outside at 8 pm. 

The box and packing was excellent and made the trip quite nicely. My biggest issue was my Hakko 936 promptly blew a fuse from the voltage change. :mad: The spec sheet clearly said it was ready for 240 v. Not even close and the internal fuse was soldered in! Well, I got a cheap voltage converter and fixed the fuse (don't ask). Up and running!

Pulled out the clearly labeled bags and started slinging. I would recommend updating the build pictures because they are outdated. I had put in d12 and d14 first and later figured they were originally the LEDs that are in the tweaks section. I am doing fine because the silk screen is great and it was clear what to do even without the build instructions. Between the clearly labeled bags and board screening no real issues exist. 

My only niggle is that a few of the back side pads are so small that it is difficult to get a medium size iron head in there to get a good heat transfer. I found it quite easy to fill the r7 hole when soldering r6. Same with r8and 9. Remember to flux the solder wick before use and all will be fine. 

My impression so far is that this is an easier project than the Mini-Max. It is certainly easier than the AMB y2+. I am enjoying the project and will probably bore you with more posts as I go.


----------



## FishHead

Pic of D12 and D14. Hopefully in the right direction.


----------



## tomb

fishhead said:


> Pic of D12 and D14. Hopefully in the right direction.


 

 Yep - those are correct.
  
 Don't forget the SMD snubber capacitors on the back side under D5, D6, D7, and D8.  Those are not labeled with silkscreen at all.  There are no other SMD parts in the build, so hopefully - that's self-explanatory. 
	

	
	
		
		

		
		
	


	



  
 I will try to update the website/build thread when I get a chance.  I've always wanted to detail the hardware as well - it is not trivial.  There are a few key points with the hardware:

Bolt on the IEC inlet to the back plate and PCB before soldering it to the PCB.  This ensures that everything lines up with the case.  It also establishes the proper slot.  Once the backplate is bolted to the IEC, there's only one slot the PCB will fit in.  This is clear on the existing website.
Black washers go on the back plate - two for the IEC inlet, one for the screw that secures the RCA jacks.
The Flat-head Socket Cap Screws are the case screws and the tiny Bondhus hex wrench is used for those.  I include the Bondhus hex wrench for every kit/build now, because removing the case lid is required to change out 6J6-type tubes and it makes everything easier.  (E90CC's are tall enough that tube rolling with them does not require taking the lid off.)
Washers are needed under the tabs of the choke to get a good mount on the PCB.
The safety ground is a PITA, but absolutely needed for safety.  Be sure to scrape off the anodizing around the hole on the inside of the case bottom.  The only way I've made this work is to bend the wire in such a curve that the lug lines up with the hole in the PCB.  Line it up with the screw hole in the case bottom, and fish through a socket head cap screw (3/8" long) from the top hole in the PCB and through the lug hole and the case bottom hole.  If you hold the case sideways, the screw should stay on the end of a socket wrench while you're fishing.  Luckily, I always use 22 ga Teflon SPC for hookup wire - it's stiff enough that it holds its shape when bending.  That makes things easier in terms of lining up the holes and screw.
The rubber bumpers are absolutely required or the standoff/grounding screws on the case bottom will be scraping on your desktop.


----------



## tomb

OK - I've updated a couple of pages to reflect the new PCB V1.02:
Torpedo Layout
Torpedo Board
  
 Also, I added a new construction page that takes care of much of the above, especially the black anodized case and special hardware:
Torpedo Black Case and Hardware Tips


----------



## FishHead

Thanks for the update! Things are going swimmingly but I am now at the Hammond "choke" point :rolleyes: (couldn't resist). I have two questions. Is it secured with two of the short flat head socket screws and second is the orientation such that the leads are really short or are the leads looped back to the r2 holes?

As for the snubber caps. Those things are for the younger guys. I dropped one! Thank goodness it was on a tile floor and after a little groveling around I was able to find it. I only dropped one more after that one and got a lid to put them in. It was a relief to get them on the board.


----------



## FishHead

Renember that children song. One of these things is not like the others? Well I found a cap that is a smidgen too large.


----------



## FishHead

dsavitsk said:


> The impedance of the bias supply is a function of the the source impedance to the transistor's base, and the Hfe (~Rs/Hfe). With the LEDs, the Source Z is ~11 Ohms. Since Hfe is ~300, that means that the bias Z is less than an Ohm. This impedance is multiplied by the mu of the tube and added to the Zout of the plate which is why keeping it low is important here -- especially as the rp of the 6J6 is not particularly low.
> 
> But, bypassing the LEDs may lower this even more. We thought it was incidental, and neither of us could hear a difference. On the expensive version of this amp, I don't bypass.




I don't know what this is saying in laymens terms. Being a layman, I want to fill the holes  unless I have a reason not to. What is the expensive version of the amp? 

Just thought I'd ask as I'm in the middle of the build. :wink_face:

Oh, I have been playing with the choke. Please note, the tabs on it do not lie level with the bottom of the choke. I'm not sure just yet what I wish to do. The least stress on the pcb would be to put a washer under the tab between it and the board. But a washer at each point (above tab, below tab, under board) just does not give enough thread to start a nut with the short screw.


----------



## tomb

fishhead said:


> Thanks for the update! Things are going swimmingly but I am now at the Hammond "choke" point
> 
> 
> 
> ...


 

 No, the flat head socket screws are only for the endplates.
  
 Use the 4-40 x 3/8's for the choke.  Use a screw + washer on the top of the choke tab(s), then place a washer(s) between the tab(s) and the PCB.  Finish up with a washer, lock-washer, and nut on the bottom of the PCB.  Do this x 2 to get both tabs mounted.  Just an FYI, but every single 4-40 screw should have washer under its head, except for the endplate case screws.  Likewise, every single 4-40 screw assembly will have a lock-washer, except for the endplate case screws (flat-head socket screws) and the RCA jacks screw.  The standoff assemblies should have the lock-washer between the screw head above the PCB and a washer.  Just use a short 4-40 x 1/4 with a single washer on the bottom of the case to screw into the standoff from the other side. 
  
 Cut the choke leads to fit to the holes next to the R2 holes.  *Remember, though - measure twice, cut once!  *If you get them too short, you can't get them back.  Anyway, the PCB pads for the choke leads are separate.  The R2 holes are way too close; there's quite a bit of bending of the leads as it is.  The choke lead holes are the very large pads on the edge of the choke square silkscreen - at the end of D4 and R1.
  
 All SMD should be executed with tweezers.  You pre-tin one of the pads by melting solder on it, then grab the SMD part with tweezers in one hand and while melting the tinned pad with the soldering iron, position an end of the SMD part on the pad with the melted solder.  Remove the iron, wait till the solder cools, then remove the tweezers.  Go back and solder the other end of the part to the other pad and you're done.
  
 FYI, but every DAC on diyforums.org has SMD soldering explained in excruciating detail.  Something like a 1206 capacitor is even easier than through-hole soldering once you learn how to do it.


----------



## tomb

fishhead said:


> Renember that children song. One of these things is not like the others? Well I found a cap that is a smidgen too large.


 
 Try again. 


fishhead said:


> Renember that children song. One of these things is not like the others? Well I found a cap that is a smidgen too large.


 

 Hmm ... I believe Auricap makes a 4.7uf in 400V.  That would work, but I can't seem to find one available right now. So, maybe they're not available in that voltage anymore.


----------



## tomb

fishhead said:


> dsavitsk said:
> 
> 
> > The impedance of the bias supply is a function of the the source impedance to the transistor's base, and the Hfe (~Rs/Hfe). With the LEDs, the Source Z is ~11 Ohms. Since Hfe is ~300, that means that the bias Z is less than an Ohm. This impedance is multiplied by the mu of the tube and added to the Zout of the plate which is why keeping it low is important here -- especially as the rp of the 6J6 is not particularly low.
> ...


 
  
 1. Believe me, capacitors at C7 and C8 make absolutely no difference at all.
  
 2. The expensive version of the amp is based on a different tube type and a foreign toroid as the PT.  It's not economically feasible to build/sell it for the performance return.  It's quite a bit more expensive.  We've been toying with building one using the same Edcor PT, but results are a long way off, even assuming it works.
  
 3. I've said this a few times, but maybe it hasn't caught on. 
	

	
	
		
		

		
		
	


	




  Yes - the Hammond choke tabs are warped.  That's why you need washers between the tabs and the PCB.  DO NOT torque the tabs down without washers in those positions.  You will destroy the PCB.  You do not use the short screws - use the 3/8" long 4-40 socket head cap screws.  You have almost an inch below the PCB and an inch-and-a-half above the PCB.  There is absolutely nothing to gain by using a short screw. 
	

	
	
		
		

		
		
	


	




  The only thing those are used for are the three standoffs.  That's because there's not enough thread length to work with screws going in on both sides of the standoffs and taller screws would stick further out the bottom than the rubber bumpers.


----------



## FishHead

Yep, you did say that but I guess it had not sunk in about the washers on the choke. I will post some pictures of the choke build later for guys like me who can read but not quite comprehend on some days

My problem was keeping track of ths SMD while on the table and picking them up. Tweezers! What a great invention. Just didn't have any at the time. 

The caps may be available at thetubestore. That is where I got the big ones. I ordered a set of the 400v ones so I can compare against the other ones when I get back stateside. 

Still having fun with the build.


----------



## dsavitsk

fishhead said:


> I don't know what this is saying in laymens terms. Being a layman, I want to fill the holes  unless I have a reason not to. What is the expensive version of the amp?




This is just saying that you want the bias supply's impedance to be as low as possible, and that theoretically including the capacitors makes it lower. In practical terms, the difference is negligible. Using the caps may even be detrimental.

The expensive version of the amp is this one: http://www.ecpaudio.com/L2.shtml


----------



## tomb

fishhead said:


> Yep, you did say that but I guess it had not sunk in about the washers on the choke. I will post some pictures of the choke build later for guys like me who can read but not quite comprehend on some days
> 
> My problem was keeping track of ths SMD while on the table and picking them up. Tweezers! What a great invention. Just didn't have any at the time.
> 
> ...




Sounds good!

Make it a good pic on the choke and I'll post it on the website. I apologize for not having it detailed already.


----------



## FishHead

What you need


Top side stack


Bottom stack w/ lock washer.



Where I cut



All choked up.


----------



## tomb

All choked up -


----------



## dpump

dsavitsk said:


> This is just saying that you want the bias supply's impedance to be as low as possible, and that theoretically including the capacitors makes it lower. In practical terms, the difference is negligible. Using the caps may even be detrimental.
> 
> The expensive version of the amp is this one: http://www.ecpaudio.com/L2.shtml


 

 This is confusing. If the capacitors are making the impedance lower and that's a good thing, how can they also be detrimental? I installed capacitors in my amp since I happened to have them. Should I remove them? What would be the detrimental effect of having them installed?


----------



## FishHead

Missed it by that much. I got it all cased up and ready to plug in and realized the fuses were 110 v. This weekend I will track some 220s down. I decided to go with the Mundorf Aluminum EVO caps first.

 It was a fantastic and fun build experience. The finished product is very professional looking.

 I have followed the development from the beginning and respect the significant sustained effort put in. I certainly bennifited from it. Thank you and props to everyone who contributed along the way.


----------



## dsavitsk

dpump said:


> This is confusing. If the capacitors are making the impedance lower and that's a good thing, how can they also be detrimental? I installed capacitors in my amp since I happened to have them. Should I remove them? What would be the detrimental effect of having them installed?




If the impedance is different at different frequencies, it could cause phase issues. I feel like someone measured such an effect on a similar circuit, but I can't remember when or where I saw that, so I don't know if it is actually something to be concerned about here. The best I can say is to try it both ways and see.


----------



## gabriel-dan

Hi,
 I read somewhere in this tread that the Torpedo might not be a suitable amp to drive orthodynamic headphones. Has someone actually used it with something like Hifiman HE 500 or LC2?. I am tempted to purchase the kit from Beezar , however not sure it will drive my orthos to a proper  volume. Tx


----------



## Punnisher

I had a brief test with my Torpedo and two pairs of orthos at a meet. The HE400 and HE500 were both incredibly warm sounding compared to any dynamics I've tried. This may sound like a plus, but it was unreasonably warm and bassy, almost as if you'd taken a graphical EQ and arranged the sliders to form an aggressive downward slope. Volume was sufficient but you would run out of headroom with a low voltage source.
  
 I listened to these same headphones with solid-state and hybrid-tube amps which fared better with a flatter frequency response.
  
 I was running Telefunken E90CC which are, when used with dynamics, on the lean side.
  
 Any other impressions are appreciated, as I'll be looking into orthos in the future as well.


----------



## FishHead

I am shopping for a set of headphones and am interested in any impressions. My budget quite flexible and I may manage the LCD-xc. I plan on auditioning the lcd xc, LCD 3, senn 600 and senn 800 next month assuming I can get my rt channel working. I just auditioned the audio technica ath-m50x. My impressions were they did not fit well, had a etched treble, bit of a recessed mid and strong bass. I was using the 5964 tubes when my rt channel stopped working. My diagnosis is a cold solder connection. All LEDs light properly, tube switch makes no change, both tubes heat proprrly, no shorts at b+, no change when source inputs switched, headphone change out did not make a difference.


----------



## FishHead

Ok I'm at a loss. Reflowed all so they are brite and shiny. Still out one channel. All LEDs are working and tubes are glowing nicely. Open for measurement suggestions or any other suggestions.


----------



## tomb

fishhead said:


> Ok I'm at a loss. Reflowed all so they are brite and shiny. Still out one channel. All LEDs are working and tubes are glowing nicely. Open for measurement suggestions or any other suggestions.


 

 Sorry if this seems too obvious, but if you lost the channel when you had a certain tube in, did you swap out that tube?  Swap tubes from one channel to the next?  Did the channel loss follow the tube?
  
 Short of that, one channel out should be fairly easy to diagnose - and you don't have to do this with the power on.  Check the continuity to ground on all the connections from one channel to the next.  When you find a difference, that's the problem.  You might try focusing on the tube sockets themselves and that Z (impedance) switch. It actually switches the windings in the output xfmrs, not the tubes.  If the middle pole on one side is not connected properly, you will lose the entire channel output at the headphone jack.


----------



## FishHead

No suggestions are too obvious from my standpoint. 

To answer the question: tubes were switched with no change( same channel out). Input cord was switched with no change (same channel out). Headphone was tested on separate gear and both channels work.


----------



## tomb

fishhead said:


> No suggestions are too obvious from my standpoint.
> 
> 
> 
> ...


 

 I may have been editing when you posted this - go back and look and see if you can check those things I mentioned.


----------



## FishHead

The only significant difference appears to be across the alps pot. At full vol 2.3 on the channel that works and 1.3 across the silent channel on the centec unit with the dial set to 200. Other values

Headphone jack. 22.9 and 22.6
Impedance sw. 22.9 and 22.6
 6.9 and 6.8
 6.9 and 6.8
Transformer at cap. 120.9 and 120.5

Vpot to ground. .6 and .6
 1.8 and 2.0
 - And. - to input connections

I stopped touching things when the LEDs started lighting up


----------



## FishHead

Here it is all lit up. You can even see the tube lights.


----------



## dpump

Plug your headphones in and turn the volume control up slightly. Touch the + RCA jack inputs on the inside of the amp and see if you hear a humming or buzzing sound. If you hear a sound on both channels then you have a bad connection on the RCA jack where cable plugs in.


----------



## FishHead

dpump said:


> Plug your headphones in and turn the volume control up slightly. Touch the + RCA jack inputs on the inside of the amp and see if you hear a humming or buzzing sound. If you hear a sound on both channels then you have a bad connection on the RCA jack where cable plugs in.




The inside of the jack is varnished. I tested continuity with the input cable to the board solder point with the amp off. Both sides passed with continuity only to the correct point.


----------



## FishHead

New data, checked PR and got 138, PL and got 0. I think I found the problem. Where do I go from here?


----------



## dsavitsk

Check that the larger plate load transistor is the right direction. Probably worth replacing both transistors on that side.


----------



## FishHead

dsavitsk said:


> Check that the larger plate load transistor is the right direction. Probably worth replacing both transistors on that side.




Q3 and Q5? Q3 is good. How can I tell if Q5 is the right direction?


----------



## dsavitsk

You know that one side works, right? So be sure the non-working one is mounted on the heatsink in the same orientation.


----------



## FishHead

Good point ! Any chance I blew the one I am turning around?


----------



## FishHead

Nevermind. I have to say I love solder wick and liquid flux. It made fairly quick work of the turn of a well soldered connection. The lettering on the transistors must be showing for the transistor to work. If you have any more than two LEDs lit at initial plug in you have to reverse either q5 or q6 on the side the third and or fourth led is lit. Thanks dsavitsk! Pl reads 136 v pr is 131 v. Both channels working


----------



## OJNeg

Any opinions on the coupling caps for the Torpedo? I've rolled in a pair Jantzens and I feel the differences are appreciable.


----------



## tomb

fishhead said:


> Nevermind. I have to say I love solder wick and liquid flux. It made fairly quick work of the turn of a well soldered connection. The lettering on the transistors must be showing for the transistor to work. If you have any more than two LEDs lit at initial plug in you have to reverse either q5 or q6 on the side the third and or fourth led is lit. Thanks dsavitsk! Pl reads 136 v pr is 131 v. Both channels working





 

You're lucky. Very few transistors survive a soldered short. Glad you got it working, though.

Thanks dsavitsk!

P.S. I should quit trying to respond from a phone - editing is a b*tch.


----------



## tomb

ojneg said:


> Any opinions on the coupling caps for the Torpedo? I've rolled in a pair Jantzens and I feel the differences are appreciable.



Never tried them, but then I've only tried the Clarity and Solen caps and I can hardly tell the difference between those two. In fact, I think the Solens are a tad better. Knowing that and the huge price difference between those two, I concluded that output cap differences were negligible. 

Maybe I was wrong, though?


----------



## OJNeg

Huh...I actually felt the differences were on par with the tube differences. Maybe with the Clarity caps it's not. The Solens are very good coupling caps regardless.


----------



## tomb

ojneg said:


> Huh...I actually felt the differences were on par with the tube differences. Maybe with the Clarity caps it's not. The Solens are very good coupling caps regardless.



Yep - could be the Clarity caps are simply not optimum for this application.


----------



## Kilko

Hey guys,
  
 I bought this unit a while a ago via this auction:
  
 http://www.ebay.com/itm/TORPEDO-Parafeed-Tube-Headphone-Amplifier-Pre-Order-/280891652425?pt=US_Home_Audio_Amplifiers_Preamps&hash=item4166727949
  
 The problem is, it stopped working after maybe 6 months (tubes wouldn't light up). I tried to put in 2 new fuses in and that didn't help either. So then and I just put it aside.
 After 8 months after that I decided to buy new tubes, but they won't light up either.
  
 I don't have any electrician knowledge, so I don't know what else to do. You guys probably do (and also have the equipment to fix it).
  
 Anybody wanna buy a used non-working !TORPEDO!?
  
 I live in Norway, so shipping will be calculated to your ZIP.


----------



## tomb

kilko said:


> Hey guys,
> 
> I bought this unit a while a ago via this auction:
> 
> ...


 

 OMG.  Mayflower.  That explains a lot. 
	

	
	
		
		

		
		
	


	



  
 Sorry I didn't know this when I replied to your PM's.
  
 One thing you might check right away are the power connections to the PCB from the IEC inlet.  Mayflower was known not to put in all the mounting screws (among other things) and the IEC inlet pins would break in shipment.  You may need to supply some more pics - especially around the power inlet and underneath the PCB - _before we can confirm it's even safe._


----------



## OJNeg

Has anyone played around with different E90CC variants? I like the Telefunkens but I want to see what else is out there. I might jump on some eBay tubes and report back.


----------



## tomb

ojneg said:


> Has anyone played around with different E90CC variants? I like the Telefunkens but I want to see what else is out there. I might jump on some eBay tubes and report back.


 

 The best I have are Telefunkens, but there are some Philips/Amperex (pretty much the same mfr), Siemens, and Mullards.*  Siemens are almost identical to Telefunkens, but may be cheaper.  Philips/Amperex are not quite as detailed as the Telefunkens, but have a mid-bass bloat that people may like.  Mullards - from my memory - are as detailed as Telefunkens but with deep bass.  They don't seem to have a bloat like the Philips/Amperex.  That may all be because a friend bought all I had and now scarcity has made their memory much fonder. 
	

	
	
		
		

		
		
	


	




  Mullards will probably be the rarest and most expensive you will find.
  
 There is another tube - the E92CC that is very similar to the E90CC and will work in the Torpedo.  It's another tall tube that can be changed out without taking the lid off.  Similar mfrs and similar construction, but slightly lower priced, its ratings are a little less optimum for the Torpedo than the E90CC.  I don't think they are consistently as good as the E90CC, but one might find that sterling exception that's always possible when rolling tubes. 
	

	
	
		
		

		
		
	


	




 
  
  
 * There are also several Eastern-European off-brand equivalents that may or may not sound as good as the mainline mfrs.


----------



## OJNeg

Interesting. I ordered a pair of Amperex so we'll see if my impressions fall in line with yours. They have in the past.
  
 I'll also give the E92CC a go eventually. I'm assuming the Telefunkens are good for that triode too?


----------



## OJNeg

Right now I'm wondering if I could throw in the 6C45pi tube into the Torpedo, just to see what sort of results I could get. I don't see anything in the datasheet that would make it undoable...except for the obvious task of making a suitable adapter. In fact I should get more gain and lower output Z.


----------



## tomb

ojneg said:


> Right now I'm wondering if I could throw in the 6C45pi tube into the Torpedo, just to see what sort of results I could get. I don't see anything in the datasheet that would make it undoable...except for the obvious task of making a suitable adapter. In fact I should get more gain and lower output Z.


 

 That's a Dsavitsk question, obviously. 
	

	
	
		
		

		
		
	


	




  The L-2 is pretty much the super-deluxe version of the Torpedo.  It may take more than an adapter, though.  It could be that the PT is not rated high enough for a pair of 6C45s.  Also, Dsavitsk had to use grid-stoppers with SMD chips under the 6C45 tube to keep it stable in operation.  There may be many more issues, too, of which I'm not aware.


----------



## OJNeg

Yes oscillation would be the biggest issue I might run into, as it seems that tube is very sensitive towards that. A screwy DIY adapter wouldn't help the issue I imagine....Torpedo does seem to have a 475ohm grid stopper which seems like a good value based on other 6C45pi designs I see out there. Maybe I'd have to add some compensation caps somewhere in the circuit. Also might want to reduce the resistor value going from grid to ground...
  
 But assuming the CCS is still running 15mA through the plate there shouldn't be any additional draw to stress the PT.  Heater current looks to be 440mA, which should be fine as all the 6J6 valves are spec-ed for that as well. Looking at the loan line curves, I imagine the plate will run at a higher voltage but I would expect to 6C45pi to be able to handle it without issue. It looks to be spec-ed for much higher plate current (52mA) and plate dissipation (7.8W vs 2W of E90CC).


----------



## tomb

If I remember what Dsavitsk told me, it wasn't the value of the resistor as a grid stopper, but rather, the location.  It may be similar to how in the Starving Student the gate resistor must be located right next to the MOSFET or it will oscillate.  I believe Dsavitsk told me that he couldn't get the 6C45 to stop oscillating until he used tiny SMD resistors (4 of them) right under the tube socket.


----------



## OJNeg

That sounds like quite a PITA, but I'm interested to see for myself eventually.


----------



## dsavitsk

You are going to run into two issues -- oscillation and operating points. For operating points, getting sufficient voltage drop across both the tube and the CCS while maintaining grid voltage will be the issue. It may be possible, but you'll have to play with it. If you don't it will clip horribly and may well draw grid current. Also, note that the 6C45 needs sufficient current to generate its high gm. If the current is too low, the rp will be high enough that it is not doing you any good to use. It is a delicate balance, and the Torpedo's PS may not be quite up to the task.

As for oscillation, it will without precautions. That means grid stoppers on each grid, a plate stopper, and 4 cathode stoppers. The reason for 4 cathode stoppers is so that each can be large enough to quell oscillation while all 4 in parallel will be low enough to not drop too much voltage. The stoppers really should be SMD and should be touching the socket pins. Leaded resistors may work on some tubes, but they do not work nearly as well as you simply can't get them close enough. I also found that teflon tube sockets helped.

All of that means that you probably should make small PCBs with the stoppers in place. It is the most likely to lead to success. Oscillation will result in the tube sounding etchy, brittle, bright, etc -- all the things people criticize it for sounding like. Let us know how it goes.


----------



## Wsybok

Hey,
I just finished build my Torpedo, when i test it, everything seems like good, 4 leds light up, tubes heated up without any problem.
But when came to the last step, i plugged my T90, there was no sound output, and when i use my phone as signal source, there was very very low voice(nearly no sounds ) coming out, but the volume stay constant no matter how i turned potentiometer. 
Is any one know which parts that may cause this kind of problem?? Than you.


----------



## tomb

wsybok said:


> Hey,
> I just finished build my Torpedo, when i test it, everything seems like good, 4 leds light up, tubes heated up without any problem.
> But when came to the last step, i plugged my T90, there was no sound output, and when i use my phone as signal source, there was very very low voice(nearly no sounds ) coming out, but the volume stay constant no matter how i turned potentiometer.
> Is any one know which parts that may cause this kind of problem?? Than you.


 

 Are you international or domestic?  Check the jumpers at the power transformer and be certain you soldered the correct ones.  If you're operating at half-voltage, your description is valid, but you will get very little sound.


----------



## PretentiousFood

Hey Doug, I've seen you mention the stoppers in a few posts across the web. Grid stoppers are pretty routine, but I haven't seen much mention of plate stoppers elsewhere. Its the plate's capacitive coupling to the inputs more of an issue in high gm tubes, or is it something else entirely? How would you go about sizing the resistors?


----------



## Wsybok

tomb said:


> Are you international or domestic?  Check the jumpers at the power transformer and be certain you soldered the correct ones.  If you're operating at half-voltage, your description is valid, but you will get very little sound.



Well, i jumped A to B and C to D for 120v input, is that correct?


----------



## tomb

wsybok said:


> tomb said:
> 
> 
> > Are you international or domestic?  Check the jumpers at the power transformer and be certain you soldered the correct ones.  If you're operating at half-voltage, your description is valid, but you will get very little sound.
> ...


 

 Not if you're international.  If US, then that's OK.
  
 Check the following:
 1. Diodes in their correct positions?
 2. Resistors in their correct positions?
 3. Transistors oriented correctly? (TO-220's have their lettering facing out from the heat sink.)
  
 To remove my packaging as a potential source of error, check these parts with the BOM and the silkscreen values on the PCB directly.  Measure the color-coded resistors, read the values of the V-D resistors (assuming you soldered them with the value indication up.)
  
 The Torpedo is not very complicated, circuit-wise.  Most of the ingenuity is in layout, parts selection (including the tubes), and transformer design.  That should make it easy to troubleshoot.  The transformers are impossible to solder in the wrong orientation - so are the RCA jacks, the volume pot, the tube sockets, and the headphone jack.  That leaves transistors, resistors, and diodes. (Capacitors soldered incorrectly will blow.)
  
 If none of that indicates a problem to you, then it's time to post some pics.


----------



## Wsybok

tomb said:


> Not if you're international.  If US, then that's OK.
> 
> Check the following:
> 1. Diodes in their correct positions?
> ...




Yes, I am using it in US.
I will check those tonight,
Thanks for your help.


----------



## dpump

Wsybok,
  
 Check beside the volume control to make sure you soldered the 2 jumpers there on the pcb.


----------



## Wsybok

dpump said:


> Wsybok,
> 
> Check beside the volume control to make sure you soldered the 2 jumpers there on the pcb.
> [/
> ...


----------



## dpump

Sorry, you are correct- no jumpers. I was thinking of my pcb which is an earlier one.


----------



## Iskandar Pane

Hello I'm new on this forum and I think I have a related problem with the torpedo. I finished building the torpedo yesterday. I made some other Diy project and I am very impressed about the quality of the pcb, and how everything was packed.

After finishing everything, I put on the power. The red leds lit up but within a few seconds they went out. Because I live in Europe (the Netherlands) I use jumper setting b-c 240v. I checked everthing, all components in the right place. When the leds went out, there where no strange noises, nothing smoked, the fuse still ok.

I can measure a voltage of 230v in the primary windings of the powertransformer, but no DC on the 2 secondary windings. I desolderd the PT, cleaned all the pins (coating) and soldered the PT back on again to be sure all the connections are good. Fortunately, no result. 

Do I have bad luck with a new, but broken powertransformer? Can I measure the PT with a multimeter if this is the case? Is it something else? I hope someone can help me (tombe).

Thnx

Iskandar




tomb said:


> Not if you're international.  If US, then that's OK.
> 
> Check the following:
> 1. Diodes in their correct positions?
> ...


----------



## Wsybok

tomb said:


> Not if you're international.  If US, then that's OK.
> 
> Check the following:
> 1. Diodes in their correct positions?
> ...


 
 tomb,
 I found that I forgot solder the SMD Capacitors on the back side of PCB, however it's still have same problem when I soldered those Capacitors on. (the volume stay same no matter power on or off).
 I will upload some pics tomorrow.
 and again, thank you for your help.


----------



## UKToecutter

iskandar pane said:


> Hello I'm new on this forum and I think I have a related problem with the torpedo. I finished building the torpedo yesterday. I made some other Diy project and I am very impressed about the quality of the pcb, and how everything was packed.
> 
> After finishing everything, I put on the power. The red leds lit up but within a few seconds they went out. Because I live in Europe (the Netherlands) I use jumper setting b-c 240v. I checked everthing, all components in the right place. When the leds went out, there where no strange noises, nothing smoked, the fuse still ok.
> 
> ...


 

 Ummm...
  
 I think you should be looking for AC on the Power Transformer secondary, not DC.


----------



## Iskandar Pane

Yes, I was wrong, its AC, but still nothing...


----------



## tomb

iskandar pane said:


> Yes, I was wrong, its AC, but still nothing...


 
  
  


iskandar pane said:


> Hello I'm new on this forum and I think I have a related problem with the torpedo. I finished building the torpedo yesterday. I made some other Diy project and I am very impressed about the quality of the pcb, and how everything was packed.
> 
> After finishing everything, I put on the power. The red leds lit up but within a few seconds they went out. Because I live in Europe (the Netherlands) I use jumper setting b-c 240v. I checked everthing, all components in the right place. When the leds went out, there where no strange noises, nothing smoked, the fuse still ok.
> 
> ...


 
  
 You will get nonsensical readings for AC voltage unless you are using a true, VAC RMS meter.  You should probably try to read DC, instead.  There are test points on the PCB for B+ and Gnd,
  
 There are also some things you could tell us that are not quite clear, yet.  Have the LED's gone out for good, or do they light initially then go out each time?  Do the tubes light at all?  If the tubes don't light, there could be an issue with the heater power supply (6.3VDC).  You might try measuring the Cathode lead on D9 with Gnd.  That should be the DC side of the heater secondary (B+ is the DC high side secondary).
  
 It's possible that the PT could be bad, but we've never had that happen, period.  I'm quite surprised that you were able to de-solder it in the first place, with all of those pins.  I would be extremely reluctant to mess with it again until you've exhausted all the other possibilities:
 1. Review all the transistors and ensure that they're oriented correctly.
 2. Review all of the resistors and likewise ensure that they're in the correct locations.
 3. Is there a possibility that you've wired the choke incorrectly?
  
 Just some thoughts - as with the other poster, pics might be in order.


----------



## Wsybok

tomb said:


> Not if you're international.  If US, then that's OK.
> 
> Check the following:
> 1. Diodes in their correct positions?
> ...


 
 here is some pics,


----------



## tomb

1. Can't say that choke is connected very well, but it doesn't look like it's wrong.  You should've trimmed the leads and soldered them correctly on the top of the PCB, though.
 2. Have you tried flipping the switch with the sound on?
 3. Are you using the ferrule in the headphone jack when you connect a pair of headphones?
 4. Can you measure the voltage at B+ and Gnd?
  
 Bottom line, I can't see anything obviously wrong in those photos.  It looked like you might've burned one of the LEDs, but if you say they're all lighting, that can't be it.  It's hard to see the resistors, so you might check those again.


----------



## Wsybok

tomb said:


> 1. Can't say that choke is connected very well, but it doesn't look like it's wrong.  You should've trimmed the leads and soldered them correctly on the top of the PCB, though.
> 2. Have you tried flipping the switch with the sound on?
> 3. Are you using the ferrule in the headphone jack when you connect a pair of headphones?
> 4. Can you measure the voltage at B+ and Gnd?
> ...


 
 1.I will trimming the leads and check resistors again.
 2.I keep sound on and connect my headphones without turn on the unit, very little volume can be heard thought the headphones, and then try to flipping the switch but volume stay same.
 3. I used the ferrule when I connect my headphones. 
 4.The voltage at B+ and G is 275.0 V DC.
  
  
 all leds lighting, as well as tubes.


----------



## tomb

wsybok said:


> tomb said:
> 
> 
> > 1. Can't say that choke is connected very well, but it doesn't look like it's wrong.  You should've trimmed the leads and soldered them correctly on the top of the PCB, though.
> ...


 
 1. Measure R10 and R11 - those are the resistors sitting in front of the tubes.  They should be 1M (1004 on the V-D label).  Measure R12 and R13 - those are the resistors on the outside of the tubes.  They should be 475R (4750 on the V-D label).  If you have these mixed up, it might explain a lot.
 2. I'm not understanding this - I was talking about the Z-switch on the front plate.  Turn the power on, connect your headphones, then flip the Z-switch.  Try it in the up position, then try it in the down position.  See if there's any difference.  For those T90's, the Z-switch should definitely be in the up position.
 3. OK - just checking.
 4. That's a good value for B+.  That means you have no issues with tube plate voltage and since the tubes light, you have no problems with heater voltage, either.  So, the issue must be somewhere in the tube biasing circuit just between the Wima caps and the Solens.  I suspect those resistors may be mixed up in #1.
  
 Anyway - check that stuff and let us know.


----------



## Wsybok

tomb said:


> 1. Measure R10 and R11 - those are the resistors sitting in front of the tubes.  They should be 1M (1004 on the V-D label).  Measure R12 and R13 - those are the resistors on the outside of the tubes.  They should be 475R (4750 on the V-D label).  If you have these mixed up, it might explain a lot.
> 2. I'm not understanding this - I was talking about the Z-switch on the front plate.  Turn the power on, connect your headphones, then flip the Z-switch.  Try it in the up position, then try it in the down position.  See if there's any difference.  For those T90's, the Z-switch should definitely be in the up position.
> 3. OK - just checking.
> 4. That's a good value for B+.  That means you have no issues with tube plate voltage and since the tubes light, you have no problems with heater voltage, either.  So, the issue must be somewhere in the tube biasing circuit just between the Wima caps and the Solens.  I suspect those resistors may be mixed up in #1.
> ...


 
 1. the reading for R10 and R11 is 48.67K ohm and 49.27K ohm (on pcb), but the label shows that was correct (1004F)
 R12 and R13 have no problem, reading 475.4 ohm and 476.1 and label 4750F
  
 2. when the z-swith at up position, the only thing has been notice is the louder background noise.
 In my previous post, I'm saying that I can heard a little sound when the unit power off, however volume will stay same even I power on the unit. (sorry about my English)


----------



## OJNeg

tomb said:


> 1. Measure R10 and R11 - those are the resistors sitting in front of the tubes.  They should be 1M (1004 on the V-D label).  Measure R12 and R13 - those are the resistors on the outside of the tubes.  They should be 475R (4750 on the V-D label).  If you have these mixed up, it might explain a lot.
> 2. I'm not understanding this - I was talking about the Z-switch on the front plate.  Turn the power on, connect your headphones, then flip the Z-switch.  Try it in the up position, then try it in the down position.  See if there's any difference.  For those T90's, the Z-switch should definitely be in the up position.
> 3. OK - just checking.
> 4. *That's a good value for B+*.  That means you have no issues with tube plate voltage and since the tubes light, you have no problems with heater voltage, either.  So, the issue must be somewhere in the tube biasing circuit just between the Wima caps and the Solens.  I suspect those resistors may be mixed up in #1.
> ...


 
  
 Huh...mine's considerably lower. 225V. Assuming we're talking about the point on the PCB labelled "B+".
  
 I would guess that his power supply is "unloaded" because something along the current path is open. Could be the CCS, tube, or the PNP on the cathode.
  
 If you don't mind poking around a bit more, I would measure the voltage at the anode (pin 1) and cathode (pin 7). If you're running the 6J6 you should see ~160V on the anode and 2.3V on the cathode. If you've got a steady hand, I would also measure the voltage on R4/R5. You should see 6V on that resistor.
  
 Just be careful you don't short anything with your probes. If you're not confident, don't do any more poking.
  


wsybok said:


> 1. the reading for R10 and R11 is 48.67K ohm and 49.27K ohm (on pcb), but the label shows that was correct (1004F)
> R12 and R13 have no problem, reading 475.4 ohm and 476.1 and label 4750F
> 
> 2. when the z-swith at up position, the only thing has been notice is the louder background noise.
> In my previous post, I'm saying that I can heard a little sound when the unit power off, however volume will stay same even I power on the unit. (sorry about my English)


 
  
 You should expect to see that resistance on R10/R11 if the pot is turned all the way up. If you turn it all the way down, you should see 1Meg


----------



## tomb

ojneg said:


> tomb said:
> 
> 
> > 1. Measure R10 and R11 - those are the resistors sitting in front of the tubes.  They should be 1M (1004 on the V-D label).  Measure R12 and R13 - those are the resistors on the outside of the tubes.  They should be 475R (4750 on the V-D label).  If you have these mixed up, it might explain a lot.
> ...


 

 I think the B+ voltage can vary quite a bit, but you're probably right, given his latest reply.  I guessed wrong.
  
 If I'm not mistaken, someone got those resistors mixed up once and the results were similar.  Still, something has to be wrong, because it still shows he's getting plenty of voltage from the PT and associated power supply parts.


----------



## Wsybok

0.873


ojneg said:


> Huh...mine's considerably lower. 225V. Assuming we're talking about the point on the PCB labelled "B+".
> 
> I would guess that his power supply is "unloaded" because something along the current path is open. Could be the CCS, tube, or the PNP on the cathode.
> 
> ...


 
 OJNeg,
 thanks for your help.
 the voltage of anode is only 0.1v for both side and about 1.5v for cathode. the voltage of R4/R5 is also quite low, only 0.8v.
 and also, the reading of R10/R11 became 1.5 ohm when I turned all the way down of the pot.


----------



## OJNeg

wsybok said:


> 0.873
> OJNeg,
> thanks for your help.
> the voltage of anode is only 0.1v for both side and about 1.5v for cathode. the voltage of R4/R5 is also quite low, only 0.8v.
> and also, the reading of R10/R11 became 1.5 ohm when I turned all the way down of the pot.


 

 Silly me, yes it should be a near short (not 1Meg) when pot is turned all the way down. I was wrong there.
  
 You're definitely not getting enough voltage on the anode so the tube just isn't conducting. The cathode looks like it's trying to work correctly but it's getting pulled down to ground because there's not enough current flowing.
  
 So according to Ohm's law, if you have .8V on R4/R5, you're only getting 2mA through it. It should be close to 6V (15mA). Maybe check that you've installed the correct resistor there? Power off, wait a minute or two, and check the R4/R5. Should be 402 Ohms. If that's not the issue, I would check D12/D14 next. You should see ~6.6V there when the amp is turned on. If you put that zener in backwards that could explain the problem. Let us know.


----------



## tomb

The zeners didn't look backward in the photos.?


----------



## OJNeg

tomb said:


> The zeners didn't look backward in the photos.?


 

 You're right they don't look to be backwards, but they should still be dropping ~6.6V. Good to verify. The fact that he's not getting any voltage across R4/R5 is indicative of something. I'm guessing the CCS is the issue here because if it was working and the tube (or something else below it) was the problem, we would see the anode pulled high to B+
  
 Wsybok: Just to check, you're measuring all these voltages relative to ground, yes?


----------



## Wsybok

ojneg said:


> You're right they don't look to be backwards, but they should still be dropping ~6.6V. Good to verify. The fact that he's not getting any voltage across R4/R5 is indicative of something. I'm guessing the CCS is the issue here because if it was working and the tube (or something else below it) was the problem, we would see the anode pulled high to B+
> 
> Wsybok: Just to check, you're measuring all these voltages relative to ground, yes?


 
 yes, I measuring the pin1 and pin7 relative to ground.
  
 R5/R5 seems like good, the reading is 402 ohm, but the voltage of zeners still very low, about 1.6v for both side.


----------



## tomb

wsybok said:


> ojneg said:
> 
> 
> > You're right they don't look to be backwards, but they should still be dropping ~6.6V. Good to verify. The fact that he's not getting any voltage across R4/R5 is indicative of something. I'm guessing the CCS is the issue here because if it was working and the tube (or something else below it) was the problem, we would see the anode pulled high to B+
> ...


 

 Yep - R4/R5 are the only RN60 resistors on the PCB.  Tough to get those mixed up.
  
 OJNeg's help is greatly appreciated.  I agree that the CCS appears to be the issue.  Just for kicks - and this would be my fault - can you check the labels on the Q3 and Q4 transistors?  Make certain that they're "2N5087" and not "2N5088."  Also, check the MJE350's while you're at it - ensure that's what it says ("MJE350") on the front of those transistors.  I have tons of different transistors that go into Beezar kits.  It's possible I might have got them mixed up.


----------



## Wsybok

tomb said:


> Yep - R4/R5 are the only RN60 resistors on the PCB.  Tough to get those mixed up.
> 
> OJNeg's help is greatly appreciated.  I agree that the CCS appears to be the issue.  Just for kicks - and this would be my fault - can you check the labels on the Q3 and Q4 transistors?  Make certain that they're "2N5087" and not "2N5088."  Also, check the MJE350's while you're at it - ensure that's what it says ("MJE350") on the front of those transistors.  I have tons of different transistors that go into Beezar kits.  It's possible I might have got them mixed up.


 
 Q3/Q4 are correct, they are 2N5087, I am not sure about MJE350 yet, I need unscrew those first and check, I will update later today.
  
 thank you all.


----------



## tomb

wsybok said:


> tomb said:
> 
> 
> > Yep - R4/R5 are the only RN60 resistors on the PCB.  Tough to get those mixed up.
> ...


 

 Unscrew them?  If you can't see the writing on the outside, then they're installed backwards.


----------



## Iskandar Pane

Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice .


----------



## OJNeg

iskandar pane said:


> Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice
> 
> 
> 
> ...


 
 You sure C1 didn't blow?


----------



## Iskandar Pane

Seems not, still in shape..


----------



## tomb

iskandar pane said:


> Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice
> 
> 
> 
> ...


 
  
  


ojneg said:


> iskandar pane said:
> 
> 
> > Tomb thank you for your quick reply en advice. Wsybok also thank you for posting the all pictures of your torpedo build. With the combination of the two I discovered my very S mistake. I swapped the polarity of C1!! Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice
> ...


 
  
  


iskandar pane said:


> Seems not, still in shape..


 
  
 My guess is that it would've blown, too.  Non-bipolar, electrolytic capacitors rarely survive being soldered in backwards.
  
 Still, this is the important point:
_*Now the amplifier is working. With the combination of my also new Grado's 325e it sounds very nice*_





. 
  
  
 Thanks for all the help, OJNeg!  Let's hope Wsybok has similar results!


----------



## dsavitsk

iskandar pane said:


> Seems not, still in shape..




Regardless, it needs to be replaced. It is not safe to use.


----------



## dsavitsk

pretentiousfood said:


> Hey Doug, I've seen you mention the stoppers in a few posts across the web. Grid stoppers are pretty routine, but I haven't seen much mention of plate stoppers elsewhere. Its the plate's capacitive coupling to the inputs more of an issue in high gm tubes, or is it something else entirely? How would you go about sizing the resistors?




Frankly, it was a suggestion from Morgan Jones and SY that led me to do it. A very small value is sufficient.


----------



## PretentiousFood

Cool, I'll give it a go! I already have a sense resistor to monitor plate current, I'll just move it closer to the socket. Thanks for the reply.


----------



## Iskandar Pane

Replaced C1, safety first!


----------



## tomb

Just an FYI -
  
 This is irritating, but the RCA jack assembly that was originally designed for the Torpedo is no longer made at Mouser.  I found replacements at DigiKey, but as it happens ... the Red Jack is on the top, but the Mouser version had the Red Jack on the bottom.
  
 Solution: switch the patch cables from right to left.


----------



## Daveze

Just finished the construction of the amp and about to work through the test steps...just want to confirm the fuse value for 240v. Simple maths is 125mA, or is it not such a big deal and the 250mA should be fine?
  
 By the way, seriously awesome build, looking forward to agreeing that it sounds amazing.


----------



## tomb

daveze said:


> Just finished the construction of the amp and about to work through the test steps...just want to confirm the fuse value for 240v. Simple maths is 125mA, or is it not such a big deal and the 250mA should be fine?
> 
> By the way, seriously awesome build, looking forward to agreeing that it sounds amazing.


 

 Are you international and I didn't supply 125ma fuses?  Second question: they're all rated for 250V, could that be the number you're reading on the fuse?
  
 Short answer is that the 250ma fuse will work, but will not provide the best protection.  You could fry the power transformer and the fuse would never blow.


----------



## Daveze

Hmm, I'm almost certain I read 250mA but you've got me questioning myself now...will confirm when I get home. 
  
 The level of protection was my concern, not a fan of losing the power transformer...I wasn't sure what sort of margins were afforded with the nominated fuse.


----------



## tomb

daveze said:


> Hmm, I'm almost certain I read 250mA but you've got me questioning myself now...will confirm when I get home.
> 
> The level of protection was my concern, not a fan of losing the power transformer...I wasn't sure what sort of margins were afforded with the nominated fuse.


 

 I'm not saying I didn't make a mistake, but my regular practice is to check the customer's location and provide the fuses needed for the country's voltage ... and I write it out on the J3a parts package, as in "Fuse Drawer, Fuses for 230V line voltage (125ma)."


----------



## OJNeg

Just want to mention that on Saturday I got the chance to compare the Torpedo to both the BH Crack (stock) and the Schiit Valhalla2 with my modded HD800. I was surprised to find that the Torpedo bested both of them easily. Faster, more clarity, more microdynamics, etc.
  
 So props to both Doug and TomB for providing what is probably the best ~$300-400 tube headphone amp out there.


----------



## Misterrogers

It is one fantastic little amp. I didn't get a chance to run mine with HD800's, but it drove anything high impedance wonderfully, and handle many low impedance cans capably. This little guy made me a big fan of 'Parafeeds'.


----------



## OJNeg

Yessir. I'm sold on the Parafeed topology as well. If only I could get my hands on a ECP L2...Or maybe a BH Mainline is in the future for me!
  
 I've had some fun rolling tubes with the Torpedo though. The Torpedo seems to respond well to switching out the critical components (tubes and caps). Right now I'm stuck between the E90CC (amperex) and E92CC (philips miniwatt). Both have different signatures but it's hard to say which is "technically" more capable so to speak. I keep both out of their boxes and switch 'em depending on my mood.


----------



## Punnisher

I agree. The Torpedo works wonderfully with the HD800. I auditioned it a while back and was very pleased.


----------



## Daveze

Local electronic parts store (Jaycar) didn't have any 125mA, so bought 100mA (too small) and 160mA (...not too small) fuses.
  
 My goodness this is an amazing amp. Currently running the 6J6 through a pair of AKG K240M, hearing things that I've previously never heard (Millet MiniMAX). Looking forward to rolling in the pair of E90CC and maybe then maybe some Jantzen Crosscaps...


----------



## OJNeg

daveze said:


> Local electronic parts store (Jaycar) didn't have any 125mA, so bought 100mA (too small) and 160mA (...not too small) fuses.
> 
> My goodness this is an amazing amp. Currently running the 6J6 through a pair of AKG K240M, hearing things that I've previously never heard (Millet MiniMAX). Looking forward to rolling in the pair of E90CC and maybe then maybe some Jantzen Crosscaps...


 
  
 I tried the Crosscaps in my Torpedo before moving on to the Z-Silvers. Let me know if you want them and I'll throw 'em in an envelope for you.


----------



## Daveze

How did you find the difference between the Crosscaps and Z-Silvers? What about the fit, aren't they a few mm long?
  
 I'll gladly take them...PM incoming.


----------



## dpump

See Post#535 for pictures of my Torpedo with ClarityCap MR 400V capacitors. The largest dimension on the PCB for the coupling caps is 51.75mm. The MR's are 50 mm. I guess you can fit caps longer than 50mm by bending the leads under the cap and then bending them down as there is some height to play with. I have done this on other amps. I originally had ClarityCap SA's in my Torpedo. The SA's were smooth and somewhat warm, but lacking in the amount of high end I like. After reading cap reviews, I decided to go with the MR's and I have been very pleased with them. I hear more overall detail and more high end. Didn't seem like they took long to settle in-they were a little rough at first but seemed pretty good after 5-6 hours.
  
 I have used Jantzen Superior Z caps in a couple of other amps. They are very smooth and detailed without harshness. Haven't tried the Jantzen Silver Z caps. I might have used the Superior Z instead of the MR if the Superior wasn't  56mm long. Didn't want to deal with the extra length and prefer a neater installation. I'm sure the the Jantzen Crosscaps are good, but I would personally recommend something better, as the Torpedo will easily show the improvement a better cap will bring. Maybe try the ClarityCap above the SA, the ESA.


----------



## OJNeg

Yes, I have to bend the leads under the ends to make it work for the Jantzen Silvers. A minor inconvenience. I have a bit of plastic under the caps to keep stress off the leads otherwise they wouldn't be flush with the PCB.
  
 I do agree that the Torpedo warrants better caps than the Crosscaps, but it depends on how far you're willing to dive in.


----------



## JamieMcC

Hi guys has anyone recorded running voltage readings for C11&C12 the Parra-feed signal caps? I am wondering what the normal working voltage is and the peak voltage the caps see and for how long that may be for.
 I have some caps that are rated at 310V for working load but they do have a peak rating of 500V for 30days before failing. So wondering if they might be usable if they are not to far out of spec. I note 400V quoted?
  
 Thanks
 Jamie


----------



## OJNeg

jamiemcc said:


> Hi guys has anyone recorded running voltage readings for C11&C12 the Parra-feed signal caps? I am wondering what the normal working voltage is and the peak voltage the caps see and for how long that may be for.
> I have some caps that are rated at 310V for working load but they do have a peak rating of 500V for 30days before failing. So wondering if they might be usable if they are not to far out of spec. I note 400V quoted?
> 
> Thanks
> Jamie


 

 Good question. On turn-on there's no current running through the tube so the anode (that's where the parafeed cap is coupled to) gets pulled high to B+ (~260V). It stays that way for 10-20 seconds. After the heater warms up and starts glowing the anode will drop down to its working value. It'll depend on the tube actually. I've measured 150V for the 6J6 and 90V for the E90CC.
  
 If your caps are rated for a 500V "peak" then you should be fine. Obviously the working load is much lower than that rating too. Out of curiosity, which caps are you planning on throwing in there?


----------



## JamieMcC

ojneg said:


> Good question. On turn-on there's no current running through the tube so the anode (that's where the parafeed cap is coupled to) gets pulled high to B+ (~260V). It stays that way for 10-20 seconds. After the heater warms up and starts glowing the anode will drop down to its working value. It'll depend on the tube actually. I've measured 150V for the 6J6 and 90V for the E90CC.
> 
> If your caps are rated for a 500V "peak" then you should be fine. Obviously the working load is much lower than that rating too. Out of curiosity, which caps are you planning on throwing in there?


 
  
 Thanks that's great info, the caps I hoped to try are 10uf RTI Teflon & Tin foil 310V DC originally from a batch manufactured for Audio Research (I think Misterrogers a few post above used some in his Mainline build)? 
  
 The Torpedo has been tempting me for about 18 months, but only dipped my toe into diying a year ago with a Crack build.
  
 cheers


----------



## OJNeg

Torpedo vs Crack is an interesting comparison. See what you think.


----------



## dpump

jamiemcc said:


> Thanks that's great info, the caps I hoped to try are 10uf RTI Teflon & Tin foil 310V DC originally from a batch manufactured for Audio Research (I think Misterrogers a few post above used some in his Mainline build)?
> 
> The Torpedo has been tempting me for about 18 months, but only dipped my toe into diying a year ago with a Crack build.
> 
> cheers


 

 The caps in the Torpedo are spec'd at 4.7uF, so I don't think you can use 10uF. The designer would have to verify this to be sure.


----------



## dsavitsk

10uF is fine. However, I find it difficult to believe that there are 10uF 310V Teflon and foil caps that will fit the board. 0.1uF certainly. 1uF, possibly. 10uF seems unlikely. It also seems unlikely that they would be available and not cost more than the rest of the kit.


----------



## JamieMcC

I to am unsure if the Teflons will actually fit having just measured one they are 56mm long x 49mm dia. Originally from a batch of 40 (I believe) custom ordered to go in one of Audio Research's reference tube preamps. A mix up in the order resulted in the right uf value but wrong physical size the batch was disposed of via TC tubes who are located close by at substantially below cost. Initially listed as a once in lifetime opportunity at around $80 each but as the stock reduced the price crept up to $120 each. From what I have found on the net RTI are supposedly the main oem manufacture for the US Teflon capacitor market suppling several of the premium makes.
  
 Quiet a few where snapped up by Bottlehead builders as the caps are a perfect substitute for the parrafeed caps in the Mainline. I brought a couple as I thought of them as a investment to keep and try in future projects over the years ahead.
  
 Edit
  
 This the pic I found whist researching on the net that made me wonder, looking at some pics of different caps installed it looks like there might possibly be enough wriggle room either side of the widest spaced terminal holes.


----------



## OJNeg

I was able to get a 57mm cap in there but had to bend the leads under.


----------



## JamieMcC

ojneg said:


> I was able to get a 57mm cap in there but had to bend the leads under.


 
  
 That is super info thank you.


----------



## OJNeg

Just an update for those interested: Out of all the tubes I've tried so far (8 pairs) the E90CC and E92CC are without a doubt the most proficient. The best I've heard for my preferences (neutral) and headphones (HD800/HD600) is the E92CC. The E90CC is good but seems to have a more rounded character. I'm going to try to grab a few more E92CC's (perhaps of the Telefunken variety) to see how the different brands will compare. Other than that, I'm going to try hacking in some high-mu, high-g there soon.


----------



## FishHead

I am currently establishing a baseline with the 6j6 with the mundorf Mcap EVO. Using my AKG 701's I find I am very happy  Simple pleasures for simpe minds.


----------



## Daveze

Which Mcap EVO are you using? I have been considering the Al+Oil as a decent cap that I can get for a decent price (ClarityCaps are tougher to get at a decent price in Oz) and avoid shoehorning a slightly oversized cap in place.


----------



## FishHead

Aluminum / Oil. No bad things to say. The next tube to roll in will be the E90cc but the 6J6 is doing such a nice job that I just have not wanted to change it. I have the clarity caps esa up for audition at some point currently sitting in a box and finally I have the auricap ega to try to get in there. If you find 600v auricaps don't get them as they are too big.


----------



## Daveze

Any feedback on the comparisons?


----------



## FishHead

I am finding the e90cc are more tword the transistor side of the house. They are very detailed yet a little less musical than the 6J6. It is a little early to make any conclusions as I have only 30 or so hrs on the e90cc. I am moving so it will be a bit before I am able to come back to the comparison.


----------



## OJNeg

fishhead said:


> I am finding the e90cc are more tword the transistor side of the house. They are very detailed yet a little less musical than the 6J6. It is a little early to make any conclusions as I have only 30 or so hrs on the e90cc. I am moving so it will be a bit before I am able to come back to the comparison.


 

 Yep, that's more or less in line with my thoughts. At this point, I've heard a few folks also say they like the 6J6 more than the E90CC. I can definitely see why. The 6J6 tends to be more macro-dynamic and have more bass slam. At the same time they also have a more organic texture than the E90CC which is slightly dry in nature. It's going to come down the the headphone in question.


----------



## UKToecutter

The problem is that all listening is subjective.
 Personally, I find the 6J6 type tubes a little 'harsh'.
 The one exception I've found is the Mullard M8081 / CV4031 which I feel is the best of the 6J6 types.
 I've been swapping round between a pair of Valvo E90CC's, SQ (special Quality) Miniwatt E90CC's and a pair of RFT ECC960's.
 For my setup and my ears the Miniwatt and the RFT's are the best.  I can't tell them apart.
  
 The Torpedo is a fantastic amp.  I love it!!!
  
 Many thanks to dsavitsk and tomb for providing us all with hours of entertainment.


----------



## tomb

uktoecutter said:


> The problem is that all listening is subjective.
> Personally, I find the 6J6 type tubes a little 'harsh'.
> The one exception I've found is the Mullard M8081 / CV4031 which I feel is the best of the 6J6 types.
> I've been swapping round between a pair of Valvo E90CC's, SQ (special Quality) Miniwatt E90CC's and a pair of RFT ECC960's.
> ...


 

 Thanks for the kind comments - you've given us a lot!!
  
 I mostly agree with you and understand the impression that the 6J6 gives a better bass slam, but you are correct that they are a little "harsh."  That's because the distortion is a bit higher and you'll hear it on loud and elevated multi-voice passages.  I've also purchased the Mullard CV4031's that you've recommended, but I'm not certain that they're that much better than a good Sonotone 6J6W or similar.  _That's only my opinion, though._  I have some ECC960's but have not got around to trying them, yet.  One other tube that people might try as a somewhat cheaper alternative to the E90CC is the E92CC.  It's almost an identical tube with slightly different ratings.  It has a tad bit more distortion than the E90CC, but is still in a much better class than the 6J6.
  
 That said, a little perspective is perhaps in order: even with the 6J6, the sound quality far surpasses other tube amps in its price range.  Realize that the 6J6 is still available for $1 (ESRC Tubes until tomorrow!) or a bit more at most places.  This final rendition of the Torpedo has taken some time and a lot of work from Dsavitsk - even Morgan Jones and Kevin Gilmore helped along the way to pinpoint/solve the noise issue.  As a result, I can finally brag: the Torpedo is truly one of the finest tube amplifiers available.  The fact that it's available in PCB form as a DIY kit makes it even more valuable and unique, IMHO.
  
 Anyway, I know I'm a MOT, so my motives and opinions are supposedly questionable and biased, but still ... it's wonderfully exciting to be able to supply something from Beezar that performs at this level of quality.


----------



## Punnisher

MOT or not, I totally agree with your last statement. I've listened to a lot of amps that fall on either side of the Torpedo's pricetag and I always favor the Torpedo. It's the best amp for dynamic headphones I've ever used.
  
 I'm so glad the E90CC was discovered because I wouldn't be making that claim otherwise. It brings a whole new level of awesome to the amp.


----------



## dsavitsk

Is now a good time to say that we've been talking about a Torpedo 2 for a while? We've prototyped a few designs. The idea is not to make an incremental improvement, but to make a totally different amp with a different topology and different tube type in a similar form factor while reusing some of the major parts. So it won't render the T1 obsolete which is not going anywhere, and it will likely cost a bit more. Hopefully we'll have something concrete this winter/spring? 

:veryevil:


----------



## UKToecutter

It is a good time to say 
 I await the official and detailed announcement with baited breath.


----------



## JamieMcC

dsavitsk said:


> Is now a good time to say that we've been talking about a Torpedo 2 for a while? We've prototyped a few designs. The idea is not to make an incremental improvement, but to make a totally different amp with a different topology and different tube type in a similar form factor while reusing some of the major parts. So it won't render the T1 obsolete which is not going anywhere, and it will likely cost a bit more. Hopefully we'll have something concrete this winter/spring?


 
  
 Sounds very interesting


----------



## FishHead

dsavitsk said:


> Is now a good time to say that we've been talking about a Torpedo 2 for a while? We've prototyped a few designs. The idea is not to make an incremental improvement, but to make a totally different amp with a different topology and different tube type in a similar form factor while reusing some of the major parts. So it won't render the T1 obsolete which is not going anywhere, and it will likely cost a bit more. Hopefully we'll have something concrete this winter/spring?
> 
> :veryevil:





Happy New Year!


----------



## OJNeg

uktoecutter said:


> The problem is that all listening is subjective.
> Personally, I find the 6J6 type tubes a little 'harsh'.
> *The one exception I've found is the Mullard M8081 / CV4031 which I feel is the best of the 6J6 types.*
> I've been swapping round between a pair of Valvo E90CC's, SQ (special Quality) Miniwatt E90CC's and a pair of RFT ECC960's.
> ...


 
  
  
 I haven't tried these. Did you grab them off ebay or a more reliable vendor?
  


tomb said:


> Thanks for the kind comments - you've given us a lot!!
> 
> I mostly agree with you and understand the impression that the 6J6 gives a better bass slam, but you are correct that they are a little "harsh."  That's because the distortion is a bit higher and you'll hear it on loud and elevated multi-voice passages.  I've also purchased the Mullard CV4031's that you've recommended, but I'm not certain that they're that much better than a good Sonotone 6J6W or similar.  _That's only my opinion, though._  I have some ECC960's but have not got around to trying them, yet.  One other tube that people might try as a somewhat cheaper alternative to the E90CC is the E92CC.  It's almost an identical tube with slightly different ratings.  *It has a tad bit more distortion than the E90CC, but is still in a much better class than the 6J6.*
> 
> ...


 
 I have to ask, are we talking measured distortion here or are you using distortion as a sonic descriptor? I ran RMAA tests on the different tube variants and according to my test the tubes with highest gain (6J6 = 38, E92CC = 45, etc) seemed to measure the best in terms of THD. Although I do agree that the E90CC sound cleaner and more refined, regardless of measurements. Maybe the results change with lower impedance loads though.
  
 Other than that I have to concur that the Torpedo is the best SET amp you can find at the given price. I might differ in that I feel the stock caps are holding it back a bit. Although they're not bad sounding caps in an absolute sense. (Probably way better than your average electrolytic). My experience tells me that a better coupling cap takes this amp above and beyond the competition. The way I see it, after that's taken care of, you can roll tubes to your delight and the Torpedo will respond very well to changes. The chase never ends, sonic bliss is always around the corner of course :rolleyes:
  
 Along the same lines, I'm curious as to what the Torpedo 2 can bring to the table.


----------



## UKToecutter

I got them through eBay.
 The seller was yitry.
 Item number 260747088812


----------



## tomb

ojneg said:


> uktoecutter said:
> 
> 
> > The problem is that all listening is subjective.
> ...


 

 You'll have to ask Dsavitsk.  I think it was a simple matter of mu values that are different when applied to the theoretical circuit calculation.  My listening experience has proven this out, but I suppose that could be a self-fulfilling delusion.


----------



## dsavitsk

ojneg said:


> Along the same lines, I'm curious as to what the Torpedo 2 can bring to the table.




If nothing else, the new one is different for the sake of being different not only from the "1", but also from anything else I am aware of. Beyond that, and without getting into specifics, it has some features to recommend it such as lower impedance for driving the transformer, lower distortion, some nice tube rolling options, lower heater current which translates into lower noise, etc.

As for tube rolling the original, you're asking the wrong guy. I have not played with many different 6J6 variants.


----------



## FishHead

Is it too early to start a T2 thread?


----------



## tomb

fishhead said:


> Is it too early to start a T2 thread?


 

 Maybe ... you guys please remember that it took us over 3 years to get to this point. 
	

	
	
		
		

		
		
	


	



  
 I have every confidence in Dsavitsk, but stuff happens ...


----------



## dsavitsk

tomb said:


> I have every confidence in Dsavitsk, but stuff happens ...




Ha! This is Tomb's very polite way of saying I have been pathetically slow lately  I wouldn't start a thread just yet. We'll announce more when I get my act together.


----------



## NuClear235

Please at new models add space in case in area at pot possition. To be possible to change pot to Attenuator:
 http://www.ebay.com/itm/Dale-23-Step-Ladder-type-Attenuator-Volume-Control-Log-50K-Ohms-Stereo-/321211481302?pt=Vintage_Electronics_R2&hash=item4ac9b23cd6


----------



## JamieMcC

I used the RN55 series Dales in one of my attenuators  (Glass-ware A5) they have been a joy to listen through.


----------



## tomb

I don't want to be discouraging about the attenuator suggestion, but let me offer two points:
  
 1. Dsavitsk used the Alps RK27 for his top-of-the-line, Summit Hi-Fi L-2.  He also used them in the Black Diamonds.  There are numerous other instances of extremely high-level amps, including balanced and electrostatic, using 4-channel versions of the RK27.
 2. The Torpedo PCB has mounting holes all along the perimeter.  Plus, Beezar has always offered the PCB's for separate sale.  So, you could build your own case design and off-wire anything you can dream up.


----------



## HiGHFLYiN9

tomb said:


> I don't want to be discouraging about the attenuator suggestion, but let me offer two points...


 
 Very valid points. There are no limits with your own chassis


----------



## NuClear235

It was just the tip for new future version of amp.
-bigger space around pot
-Add possibility that LEDs under Tubes will start glow after end delayed start of relay.
So will be shown, that amp is ready. 
But Center LED stay permanently powered on to be shown that amplifier is switched ON.
(Maybe is Delay circuit not used because output transformer.)

I have MiniMax not Torpedo. There is really little space around Blue Velvet Pot. 
But Your case is so sexy-make my own I want still not


----------



## jboehle

Quick question: are the build instructions on the Torpedo website all up to date?  I'm about to start my build but it's been a while since I read through this whole thread.


----------



## tomb

jboehle said:


> Quick question: are the build instructions on the Torpedo website all up to date?  I'm about to start my build but it's been a while since I read through this whole thread.


 

 The last page in the series of construction articles is completely up-to-date with the newest PCB's:
http://www.diyforums.org/Torpedo/TORPEDOconstruct11.php
  
 The additional notes at the bottom of the page sum up all of the changes.


----------



## NuClear235

Any rumor or spy photos of T2? :evil:


----------



## JamieMcC

Quick question about the enclosure of the amp and heat dissipation, I was thinking of using a wood veneer to cover the top and sides of the enclosure with apertures for vents but obviously am mindful that this will prevent heat generated from being transferred so effectively through the case for cooling. Might heat sinks mounted on the underside of the base help offset this cosmetic approach or am I being unduly cautious about the amount of heat the amp dissipates through its enclosure and leaving the base and ends as normal might still be sufficient?


----------



## tomb

jamiemcc said:


> Quick question about the enclosure of the amp and heat dissipation, I was thinking of using a wood veneer to cover the top and sides of the enclosure with apertures for vents but obviously am mindful that this will prevent heat generated from being transferred so effectively through the case for cooling. Might heat sinks mounted on the underside of the base help offset this cosmetic approach or am I being unduly cautious about the amount of heat the amp dissipates through its enclosure and leaving the base and ends as normal might still be sufficient?


 

 The Torpedo gets hot.  Before we got the case design down pat, it used to get _very_ hot.  I would have to suspect that veneer would de-laminate over time due to the heat.  The power transformer generates a lot of heat, but the tubes even more.  Things are a little cooler with the E90CC tubes, but the 6J6's are a couple of marshmallow toasters all by themselves.
  
 I'm not sure how heat sinks on the bottom would do anything.  Even the largest heat sink needs to provide heat transfer to the air or radiation to surrounding objects.  If the heat sinks are underneath, it's difficult to see how the heat is going to escape.  Or, maybe I'm not understanding what you're describing?


----------



## JamieMcC

Thanks it doesn't look such a good option if the amp diffuses significant heat through the case work.


----------



## tomb

jamiemcc said:


> Thanks it doesn't look such a good option if the amp diffuses significant heat through the case work.


 

 Yeah, probably ...


----------



## tomb

The Torpedo is temporarily out of stock.  I've had some transformer issues with Edcor and I've gotten hit in-between enclosure manufacturing runs.  New cases should arrive within a day or two, but I have to have them anodized and laser-etched locally.  That may take another 2-3 weeks.  Rest assured, I will get the Torpedo back in stock as quickly as possible.


----------



## OJNeg

tomb said:


> The Torpedo is temporarily out of stock.  I've had some transformer issues with Edcor and I've gotten hit in-between enclosure manufacturing runs.  New cases should arrive within a day or two, but I have to have them anodized and laser-etched locally.  That may take another 2-3 weeks.  Rest assured, I will get the Torpedo back in stock as quickly as possible.


 

 At least that means they must be selling!


----------



## tomb

ojneg said:


> tomb said:
> 
> 
> > The Torpedo is temporarily out of stock.  I've had some transformer issues with Edcor and I've gotten hit in-between enclosure manufacturing runs.  New cases should arrive within a day or two, but I have to have them anodized and laser-etched locally.  That may take another 2-3 weeks.  Rest assured, I will get the Torpedo back in stock as quickly as possible.
> ...


 

 Yes, that's exactly right. 
	

	
	
		
		

		
			





  There's quite a demand for the Torpedo, now.
  
 Good news, though - Edcor is currently working on a new set of transformers.  Plus, a new shipment of cases arrived on my doorstep yesterday.  I'll wash them all this weekend and take them to the anodizer on Monday.  They'll probably keep them a week and then off to the laser-etcher for another week.  If we're lucky, this will all coincide with receiving Edcor's replacements.
  
 Meanwhile, Dsavitsk sent me quite a few new Torpedo designs that I'm currently playing with.  We've always had the Torpedo II, but it used a prohibitively expensive toroid to remove the noise.  That was all before the rectifier changes/snubber caps, though.  Now I have a Torpedo II with a standard Edcor PT and I'm applying the tweaks.  If it works out, we may be ordering PCB's right away. 
	

	
	
		
		

		
		
	


	



  
 Then there's the Torpedo III ...
  
 Lots of exciting stuff happening!


----------



## OJNeg

tomb said:


> Yes, that's exactly right.
> 
> 
> 
> ...


 

 Very cool. If you guys need any feedback or beta testers I'm your guy


----------



## OJNeg

Quick question...what are the ratings on the power transformer for both the B+ and heaters?


----------



## tomb

ojneg said:


> Quick question...what are the ratings on the power transformer for both the B+ and heaters?


 

 200V at 40ma and 8.5V at 1.5A.


----------



## 00940

tomb said:


> 200V at 40ma and 8.5V at 1.5A.


 
  
 Tomb and/or Dsavitsk will confirm/infirm... from memory, Edcor's rating are for DC draw with a capacitor input supply. Most other manufacturers specify their transformers for AC current (which means you have to derate them by a factor of almost 2).
  
  
  
 as an aside: if you guys aren't too far into prototyping: have a serious look at the lm2596 for heaters. A switcher reg gives quite a few advantages: you get less losses and thus less heat and you can use a higher voltage/lower current secondary (easier on the transformer). And be sure to try the 6E5P. It's a great tube for this particular application.


----------



## dsavitsk

00940 said:


> as an aside: if you guys aren't too far into prototyping: have a serious look at the lm2596 for heaters. A switcher reg gives quite a few advantages: you get less losses and thus less heat and you can use a higher voltage/lower current secondary (easier on the transformer).




Interesting thought. The plan had been to use the same PT and OPTs. But I can definitely see your point. If we end up redesigning, that is not a bad option -- I use those for breadboarding all the time. The existing heater reg is an LDO, so we could actually go the other way and drop the voltage a little with likely the same effect.




00940 said:


> And be sure to try the 6E5P. It's a great tube for this particular application.




Looks like a good tube and worth considering. Thanks. For now, the T2 has a totally different topology.


----------



## 00940

dsavitsk said:


> For now, the T2 has a totally different topology.


 
  
  
  
 A good reason to wait a bit  I'm curious to see what you came up with, considering the use of the same output transformers.


----------



## SomeGuy82

Hi all, built the torpedo. Tubes glow, leds light up, but I only get mono sound. Tried everything. Did anybody else run into this problem? If so, any solutions? Please let me know. Thanks!


----------



## dsavitsk

Did you try swapping tubes and/or cables to see if the working side moves? The most likely reason is a bad solder joint -- look them all over carefully.


----------



## tomb

Maybe I'm wrong, but I was thinking that when he said "mono," he meant both channels were working, but he's not getting stereo.
  
 I'm not saying that's impossible, but pretty close to it with the Torpedo.  This is usually caused by messing up the input wiring or on the volume pot: switching a signal wire for ground, for instance.  This is impossible with the Torpedo, though, because not only the volume pot is PCB-based, but so are the RCA jacks.  There are solid traces in the PCB in-between.
  
 Can you supply us with a clear photo of your assembled PCB?  There are some extra pads that are not used and I'm wondering if maybe you soldered something into them?  (This might happen at the headphone jack, for instance.)  Just a guess, but it doesn't make much sense.
  
 On the other hand, my assumption of your problem may be completely wrong.  In which case, please refer to dsavitsk's advice above.


----------



## SomeGuy82

Hey guys. Tried switching both the tubes and the cables. Same problem. I noticed that when I push the head phone jack half way into the input, both sides play but it's still mono. I've attached the pictures of the build below. Any ideas? I guess I may have to reheat all the wiring this weekend to be sure. Thanks a lot for your help! Really appreciate it!


----------



## Punnisher

It's common for headphone jacks to play mono in both channels when partially inserted. This happens when the tip and ring come in contact with the right channel at the same time.


----------



## SomeGuy82

punnisher said:


> It's common for headphone jacks to play mono in both channels when partially inserted. This happens when the tip and ring come in contact with the right channel at the same time.




Fair enough. But when I push the jack all the way in, sound cuts out on the left channel.


----------



## tomb

Well, you supplied excellent photos!  However, I can't see from any of them what might be wrong.  If the sound really cuts out on one channel, then dsavitsk's post is the best.  (He interpreted it correctly whether you described it that way or not. 
	

	
	
		
		

		
			





 )
  
 So, your left channel is not working.  That's discouraging, but you have a great resource - the other channel.  You can start with power off to see if you have an open circuit between any of the parts (measure for zero resistance between parts on the Left side (From the front of the PCB with the volume pot and headphone jack, the Left channel is on the Left side.)  You can reference measurements from the right side to see if they're the same.
  
 Similarly, you can do this with the power on (VERY CAREFULLY) by measuring Ground to PL and PR.  If those are the same (not zero), then turn the amp off again and re-measure the parts and compare them between the two channels (resistance).  Check to see if there's not an open circuit somewhere, for instance, at the parafeed caps, C11 & C12.
  
 Let us know what you find.


----------



## OJNeg

dsavitsk said:


> Interesting thought. The plan had been to use the same PT and OPTs. But I can definitely see your point. If we end up redesigning, that is not a bad option -- I use those for breadboarding all the time. The existing heater reg is an LDO, so we could actually go the other way and drop the voltage a little with likely the same effect.
> Looks like a good tube and worth considering. Thanks. For now, the T2 has a totally different topology.


 

 Interesting. I was halfway hoping the Torpedo 2 would use better (?) scaled up OPTs. Or maybe even roll-able ones for those of us with autistic tendencies?
  
 Any hints on the different topology?


----------



## tomb

someguy82 said:


> Hey guys. Tried switching both the tubes and the cables. Same problem. I noticed that when I push the head phone jack half way into the input, both sides play but it's still mono. I've attached the pictures of the build below. Any ideas? I guess I may have to reheat all the wiring this weekend to be sure. Thanks a lot for your help! Really appreciate it!


 
  
  


tomb said:


> Well, you supplied excellent photos!  However, I can't see from any of them what might be wrong.  If the sound really cuts out on one channel, then dsavitsk's post is the best.  (He interpreted it correctly whether you described it that way or not.
> 
> 
> 
> ...


 
  
 Any luck?


----------



## dpump

Pictures of the bottom of the pcb might show something if you haven't figured it out yet.


----------



## FishHead

I thought I would give some impressions between two caps I have used in the T1 (as we now have multiple devs). My original build used the Mundorf EVO Aluminum Oil 4.7 450VDC cap. Most of my listening was done using the 6J6 tube. I did listen to the E90s but found them to "digital" for my taste. Moving on now, I have replaced the Mundorf with the Clarity Cap ESA 4.7 3% 630 V. While my sonic signature memory is imperfect at best and mildly delusional at worst, I find the Clarity Caps are a richer sound than the Mundorfs while using the 6J6 tubes. I will be spending some time with the 6J6s and have yet to roll the E90s through the T1. PM me if you would like to try the Mundorf's out. Bottom line is that I like the Clarity Caps more than the Mundorfs. You may have a different impression.


----------



## tomb

Beezar Labs testing the Torpedo II:
  

  
 When I can't stand looking at the scope anymore or smelling the solder iron, this is on the other wall:


----------



## Avro_Arrow

tomb said:


> Beezar Labs testing the Torpedo II:
> 
> 
> 
> ...


 
  
 Nice collection of YoYos!


----------



## tomb

avro_arrow said:


> tomb said:
> 
> 
> > Beezar Labs testing the Torpedo II:
> ...


 

 Kind of fitting, isn't it?


----------



## FishHead

Kind of reminds me of following our build thread. Are you as proficient with that wall as you are with ours?


----------



## tomb

fishhead said:


> Kind of reminds me of following our build thread. Are you as proficient with that wall as you are with ours?


 

 Not really (assuming I am proficient with either one. 
	

	
	
		
		

		
		
	


	




).  I barely know how to bind and can do very little of the new tricks.  New top-flight machined, anodized, ball-bearing yo-yo's will not return to your hand unless you perform a "bind."  Most of what's on that wall are Duncan Freehands, but I have a few new ones - both plastic and aluminum.  Of course, the Freehand is still made in a number of iterations.  This is a great site that quickly shows the extent of the current state-of-the-art with yo-yo's (the yo-yo reviews and tutorials, especially):
http://www.highspeedyoyo.com/ (not a commercial site).
  
 But I digress ...  Torpedo II tests continue.  We have some issues, but I have to defer to Dsavitsk on the conclusions and improvements.  I'm no scope jockey, by a long shot.


----------



## FishHead

Great web site.


----------



## OJNeg

I'd like for 4-pin balanced connectors to be an option for the Torpedo II. It would make it easier for those of us who are already rolling with balanced amps. And since the output is going to be transformer coupled (I presume) it should be a cinch. 
  
 On the same note, will this amp sport balanced XLR inputs? I'm guessing input transformers aren't viable unless the price point shoots way up.


----------



## dsavitsk

For now, the plan is to keep the same case and transformers (and thus the same jacks and switches), and to work within those constraints. To do differently will run up the cost considerably which we would need to recoup in the price.

As for output 4-pins, even if we used them, we would need to ground the two negative pins for safety reasons. The benefits of a differential amp are in the circuit, not in the cable to the headphones.


----------



## tomb

Meanwhile, Torpedo I's are back in stock!


----------



## tomb

ojneg said:


> I'd like for 4-pin balanced connectors to be an option for the Torpedo II. It would make it easier for those of us who are already rolling with balanced amps. And since the output is going to be transformer coupled (I presume) it should be a cinch.
> 
> On the same note, will this amp sport balanced XLR inputs? I'm guessing input transformers aren't viable unless the price point shoots way up.


 

 Dsavitsk answered this, but I thought I'd quote you so I could thank you for displaying the Torpedo at Can Jam SoCal!
  
 On Tyll's InnerFidelity: http://www.innerfidelity.com/content/canjam-socal-2015-member-table-ojneg-and-bill-p


----------



## Sopp

When is the expected date for release?


----------



## dsavitsk

I think we are hoping for early summer for the new one. We have done numerous prototypes, and we are now finalizing the design.


----------



## OJNeg

Excellent!
  
 So I'm guessing that current Torpedo owners will be able to move over to this new amp and save a lot on the transformer cost....unless there's a reason we would want both amps


----------



## tomb

Ooh.  I hate the idea of butchering one amp to build another.  Better to sell one if you decide you don't want it.  The current Torpedo is still better than any other tube-transformer-coupled amp at it's price point.


----------



## Punnisher

Yes indeed. Don't ever part out an amp unless it's helplessly broken. I think it's been made clear that the new Torpedo won't necessarily be an upgrade, but rather a different option with a different topology that utilizes a similar footprint to that of the current Torpedo. Correct me if I'm wrong.


----------



## tomb

punnisher said:


> Yes indeed. Don't ever part out an amp unless it's helplessly broken. I think it's been made clear that the new Torpedo won't necessarily be an upgrade, but rather a different option with a different topology that utilizes a similar footprint to that of the current Torpedo. Correct me if I'm wrong.


 
 We're still trying to figure out if the different topology is an upgrade or not. 
	

	
	
		
		

		
		
	


	




  It looks like the Torpedo II is simply not as much an improvement as we thought compared to the Torpedo I, especially with the E90CC's.  It simply doesn't make sense to expend the effort and investment when it might be an either-or choice.
  
 The Torpedo III has the potential to be quite a bit better, but we're in the middle of working out the preliminary prototyping process.  I've been listening to the first one extensively for the last several weeks/months and am mightily impressed, but there are a couple of issues we're trying to lick with it.  Right now, I'm listening to it with 5963's and the response and performance is fantastic.  However, the design goal is to be able to use an entire range of different gain tubes such as 12AT7, 12AU7, etc., but the response suffers a tiny bit on the high end with those other tubes (meaning not as extended as Torpedo I).  Dsavitsk has built the 2nd prototype based on this finding (from the one I've been listening to), but he's found out enough that a 3rd PCB is in the works.  That's essentially where we are right now.
  
 There are also some transformer combinations that may elevate it to near-summit quality, but that option may not be possible in the current casework.  I'm hoping that we have an option for a noticeable improvement over the Torpedo I with the existing transformers and the existing case (but it will mean a price increase) and then an all-out summit-fi option with much higher quality transformers and caps.
  
 Dsavitsk may sell the summit-fi option directly from ECP Audio with that option, but we're not really certain, yet - or whether we can get the current bugs out.  This is similar to what we've already done, because the Torpedo I can be thought of as a lower-grade version of the ECP Audio L-2.
  
  
 Dsavitsk can hopefully correct me if I've stated anything wrong, but I thought it might be useful to further elaborate on what's going on.  Meanwhile, the Torpedo I is still available and will remain so for the foreseeable future. (not so with the MiniMAX, I'm afraid)


----------



## OJNeg

I'll have to get both and then compare on my own time then


----------



## dsavitsk

Not much more to add other than we are working on it and the new circuit seems promising. The II was a 6922 based Beta follower. The circuit is OK, but as Tom said, it wasn't special enough to pursue further, and it would eat rare/expensive 6DJ8s for breakfast. 

I think we both like the III better. We are trying to work out the last remaining kinks, and if it is an easy fix, we'll be ready sooner than later (weeks), and if it is not, then it will take a little longer (a month or two) and cost a little more


----------



## NuClear235

tomb said:


> Dsavitsk answered this, but I thought I'd quote you so I could thank you for displaying the Torpedo at Can Jam SoCal!
> 
> On Tyll's InnerFidelity: http://www.innerfidelity.com/content/canjam-socal-2015-member-table-ojneg-and-bill-p


 
 UUUUuuh, they said, that is excellent with Sennheiser HD800!


----------



## tomb

*TORPEDO III is coming!!*
  
 This is a prototype that I finished this weekend.  I'll let Dsavitsk explain the details.  In my layman's understanding, he's using a differential (balanced) circuit within the amp to cancel all of the common mode distortion and noise, then combining the result using the OPT's (OutPut Transformers).  The result is very similar to his ECP Audio DSHA-1, except that a tube is providing the gain stage.  Yes, this means the Torpedo III is a tube hybrid, but unlike any tube hybrid heretofore available.  Sound is remarkably detailed from deep bass to extended highs and at the same time, no harshness, no tizziness, even with the most complicated of passages.
  
 The tube basis is the ubiquitous and high-quality 12AU7.  However, unlike most amps based on the 12AU7, the Torpedo III can take a wide range of gains.  This means you can use the 12AY7, the 12AU7 and all its numerous variants, and even the 12AX7.  Versatility extraordinaire!
  
 Beyond that, the Torpedo III uses the same planform as the Torpedo I.  That means the same case, the same hardware, and the same Edcor transformers (but with a future upgrade to Cinemag output transformers).  You could even build a PCB-only and then replace it within an existing Torpedo I case.  I guess I'll have to start selling transformers to make that possible, but that's OK.  Edcor and I will have a little discussion, soon. 
	

	
	
		
		

		
		
	


	



  
 So far, I've used the Grado HF-2, AKG K712, KSC-75's, and the Sennheiser HD580 (just for the heck of it).  The Torpedo III handled all of them with ease and with a sound quality like I've never heard before, long-term. Yes, I've heard some very expensive stuff before, but that was only a headphone meet's quick impression - not something I could live with and call my own.  The source I've used is the PupDAC with the DoodleBug, perfectly adequate for great detail and low-noise.  I haven't made measurements yet, but compared to the Torpedo I (already quite good and free of audible hum), the background is very black, with absolutely no noise whatsoever.
  
 Construction is a bit tight in spots, but nothing anyone who's built a Torpedo I can't handle.  You will note the large number of box film caps.  Dsavitsk recommended them - Epcos - from Mouser, so I tried them.  I see no reason to use anything else, but the pads are quite flexible for some very expensive alternatives, for those that are interested.  You may also notice four heat sinks instead of the three on the Torpedo I.  There are several other differences, but all in all, very similar to the Torpedo I - same transformers, same Alps volume pot, headphone jack, Z-switch, IEC inlet, etc.  Just a couple of 9-pin tube sockets and some very special stuff in-between.


----------



## FishHead

Congratulations on the new baby! 

Any comparisons with the T2?


----------



## tomb

As we stated earlier, the Torpedo II does not offer any appreciable benefits over the Torpedo I and it will not be pursued.

That actually means the Torpedo I is pretty d*mn good already. We were only looking for something that would offer an obvious increase in quality over the Torp I. The reason is obvious, because the Torpedo I is not an insignificant investment.

That also means the Torpedo III must really be stupendous. Well, it is! The bad news is that also means it will cost more. However, Beezar Audio and ECP Audio have always tried to maintain a logical correlation between price and performance.

We think the Torpedo III will justify all of this - it's that good.


----------



## dsavitsk

The short answer is that the prototype T2 was OK, but it did not really do anything better than the T1. And it would have cost a little more to build. The T3 on the other hand is really a nice amplifier -- maybe we're not supposed to say that, but we would not make it available if we didn't think that was the case. We put a lot of work into it, and we're very pleased with the sound we're hearing.


----------



## diego

So ... is it an AC coupled series push pull Mosfet mu follower?


----------



## tomb

diego said:


> So ... is it an AC coupled series push pull Mosfet mu follower?




As usual, it's best to let dsavitsk answer the technical questions.

That said, it is a tube hybrid DSHA. However, the differential output devices are BJT, NPN transistors, not MOSFETs. This is the second T3 prototype built (after two T2 prototypes). The first T3 prototype used the MOSFETs. However, we found that the highs were rolled off because the MOSFETs don't present a high enough input impedence to the tubes.


----------



## dsavitsk

diego said:


> So ... is it an AC coupled series push pull Mosfet mu follower?




I looked into the mu follower topology, but for a variety of reasons chose against it. The T3 is a Long Tailed Pair with a CCS tail with differential emitter followers. It can also use MOSFET followers, but I like the BJTs better.


----------



## OJNeg

Thanks to Tom and Doug for letting this guy loose. I'm curious as to how it stacks up.
  
 Also have to say I'm very curious about possible Cinemag OPTs. I still think that even more performance can be squeezed out of the Torpedo I with better parts!


----------



## diego

Thank you for your answers. I am looking forward to see the final result as I have been wanting to build something like that for the last few months.


----------



## FishHead

LEDs under the tubes? I thought I saw one on the board in the pictures.


----------



## dsavitsk

ojneg said:


> Also have to say I'm very curious about possible Cinemag OPTs. I still think that even more performance can be squeezed out of the Torpedo I with better parts!




We are working on making this a possibility. We'll know more soon.




fishhead said:


> LEDs under the tubes? I thought I saw one on the board in the pictures.




Not quite. There is an LED between the tubes.


----------



## tomb

dsavitsk said:


> ojneg said:
> 
> 
> > Also have to say I'm very curious about possible Cinemag OPTs. I still think that even more performance can be squeezed out of the Torpedo I with better parts!
> ...


 
  
 Just an update for those interested and it elaborates a bit on Dsavitsk's post above ...
  
 We decided to wait until the Cinemags come through to make absolutely certain that no other changes are needed on the PCB.   The Cinemags are spec'd to match the pinouts on the Edcors, but you never really know, especially when dealing with two different mfrs.  Of course, the PCB is just fine with the Edcors now.
  
 Also - just an FYI on the LED.  I asked Dsavitsk for this as additional assurance in indicating whether the amp is powered on or not.  The 12AU7 tubes are pretty much completely surrounded by the case lid, even more so than the 6J6's in the Torpedo 1 because the tubes are a larger diameter.  If you have getter flashes on top, then the tubes are almost completely obscured and it becomes fairly difficult to tell if the power is on.  I've accidentally left the Torpedo 2 prototypes running for a couple of days for the same reason.
  
 Anyway, Dsavitsk has eked out every bit of current using the existing Edcor PT.  To do that, he severely limited the current to the LED.  You may find that with cheaper, high-output LEDs, the current is not even sufficient to light the LED.  I put in a cheap pink LED just for the heck of it in building the prototype.  It wouldn't light, so I thought it was in backwards until I tried replacing it and then got the full story.  So, I'll test quite a few LEDs when we release the design and make sure there's a decent selection that will provide reasonable lighting under the conditions described.


----------



## skeptic

Sounds like an awesome amp kit!  Looking forward to reading more about it as you guys approach the release.


----------



## UKToecutter

Ooh,
  
 Not sure I like the sound of that.......
 No headroom on the PT????
 At all??


----------



## tomb

uktoecutter said:


> Ooh,
> 
> Not sure I like the sound of that.......
> No headroom on the PT????
> At all??




A few things:
1. Dsavitsk is very conservative.
2. Current is very limited within the tube circuit anyway. The high-voltage conversion through the OPTs is the real source of current at the output.
3. Referring to #1 again, Dsavitsk is simply ensuring that nothing whatsoever could introduce noise in the circuit, like a PT with too much current load.

"Eke out every bit if current" was poor phrasing on my part. Again, if I've said something technically incorrect, Dsavitsk will correct me.

I don't think you'll be disappointed. It drives Grados, Senns, and AKGs with equal authority.


----------



## dsavitsk

We are running it conservatively to ensure that noise and heat are minimized. In a sense, we are running it more conservatively than in the T1 as the B+ current is similar but the heater current is reduced. If you run a bit more current, nothing will be damaged (which I think is what you mean by headroom) but I don't think much will be gained either. 

Think of it this way, the output portion of the circuit runs at ~12mA per side but that is into a 10K load. As that is stepped down into a 32 Ohm load by a winding ratio of ~18:1, the current available is multiplied by 18 (minus transformer losses). That is to say, power is conserved across a transformer. It is the equivalent of running a bit over 200mA per side. Into 300R phones, it works out to just under 100mA (with the requisite increase in voltage swing). And because the circuit itself has a low output impedance, it does not suck up much of that (which is the big advantage over the T1 and why this amp is a bit more powerful.)

Power transformers are rated not based upon what will make them burn up, but on how much current one needs to draw to make them meet their specs. So a 50W 50V transformer will deliver 1A @ 50V. If you draw a little more current, the voltage will drop, how much depends upon how it is wound. If you draw a lot more it might burn up, but we're not pushing that line.

The LED is at the end of a B+ bleeding resistor and it gives some indication that there is still voltage present. A run of the mill red or green led will light up with no problem. If you want it brighter, you can reduce the resistance, but again, there is really no benefit to doing so. I'll note to that the fact that the LED is not lighting up should not be taken as definitive evidence that there is no high voltage present. You should always measure before touching anything in a high voltage circuit, or really in any circuit.


----------



## UKToecutter

OK, I think I get that.
  
 Tom, yes it was the expression you used.
 I had a squeaky bum moment!!
  
 The thing that popped into my head was 'sag'.
 Something I might look for in a guitar amplifier but not desirable in a headphone amp.
  
 I'm sure it's all good and I look forward to building one as soon as it's released.
  
 Cheers


----------



## dsavitsk

There is a voltage regulator so no sag. And the circuit being differential always draws the same current regardless of signal.


----------



## denogginizer

When do you anticipate the release of the Torpedo 3? My Millet-Max is starting to go on the fritz ;(


----------



## tomb

denogginizer said:


> When do you anticipate the release of the Torpedo 3? My Millet-Max is starting to go on the fritz ;(


 
  
 First - just my humble opinion, but the Torpedo I with E90CC tubes blows away the Millett-MAX.  If it didn't, I wouldn't stop selling MiniMAX kits and there's only one of those left.  Second, there's no way the price is going to be comparable on the Torpedo III.  There is nothing like it on the market.


----------



## JamieMcC

The Torpedo III sounds very intriguing, I am very much looking forward to finding out some more about it.


----------



## denogginizer

TomB
 yes, I realize the MilletMax is outdated but she has served me well  I look forward to the Torpedo III, when do you think it will be available for sale?


----------



## FishHead

Millet Max serving duty driving computer speakers. The stuff you sell just works well.


----------



## tomb

fishhead said:


> Millet Max serving duty driving computer speakers. The stuff you sell just works well.


 
  
 Cool!  Thanks for that kind comment!


----------



## dsavitsk

Just a little Torpedo update -- I have been testing the first prototype of the new output transformers. There are a few small tweaks to make and I'll be testing a second (and likely final) prototype in the next week or two, but thus far the results are extremely promising. By that I mean the thing sounds great.


----------



## Blze001

Quick question: aside from price, would there be any situations where the MiniMax would be preferred over the Torpedo? I'm looking to build a pretty solid amp to act as my audio centerpiece for the next few years while I build up a nice headphone collection. Am I correct in assuming the Torpedo is more flexible in terms of what headphones it'll work with?


----------



## tomb

blze001 said:


> Quick question: aside from price, would there be any situations where the MiniMax would be preferred over the Torpedo? I'm looking to build a pretty solid amp to act as my audio centerpiece for the next few years while I build up a nice headphone collection. Am I correct in assuming the Torpedo is more flexible in terms of what headphones it'll work with?


 
  
 The MiniMAX and more - the MOSFET-MAX - would be better for low-efficiency planars and small speakers.  For all else, the Torpedoes (either one) are superior.  The most noticeable thing with both Torpedoes is the greater transparency of the output transformers compared to output coupling capacitors.  Output coupling capacitors, while pretty good with better quality audio-electrolytics, still puts a bit of a fog over the output of an amp by comparison.
  
 As for the Torpedo III, it probably has another 10-20% improvement in detail, imaging, etc., over the Torpedo I.  That said, you probably won't notice the most important characteristic of the Torpedo III until you switch to another amp or put in some long-term listening.  The ECP Audio DSHA component of the Torpedo III means outstandingly clear and fatigue-free listening.  It's difficult to describe until you've listened to one for awhile.  It has an uncanny ability to render even the harshest recordings into something detailed and musical.  The word "tizzy" is completely alien to the Torpedo III.  At the same time, the highs are even more extended and detailed than the Torpedo I.
  
 I don't know any better way to describe it, but maybe when we get these going, some of you wordsmiths can come up with better descriptions. 
	

	
	
		
		

		
		
	


	



  
 BTW, PCB's should be on order soon.  I hope to get a quote for the production run tomorrow.


----------



## FlySweep

Tom.. any chance you guys will have pre-built TIII's available?


----------



## OJNeg

flysweep said:


> Tom.. any chance you guys will have pre-built TIII's available?


 

 I'll build you one no (extra) charge and send it to you for the cost of shipping if you let me listen to it for 2 weeks


----------



## Blze001

tomb said:


> The MiniMAX and more - the MOSFET-MAX - would be better for low-efficiency planars and small speakers.  For all else, the Torpedoes (either one) are superior.  The most noticeable thing with both Torpedoes is the greater transparency of the output transformers compared to output coupling capacitors.  Output coupling capacitors, while pretty good with better quality audio-electrolytics, still puts a bit of a fog over the output of an amp by comparison.
> 
> As for the Torpedo III, it probably has another 10-20% improvement in detail, imaging, etc., over the Torpedo I.  That said, you probably won't notice the most important characteristic of the Torpedo III until you switch to another amp or put in some long-term listening.  The ECP Audio DSHA component of the Torpedo III means outstandingly clear and fatigue-free listening.  It's difficult to describe until you've listened to one for awhile.  It has an uncanny ability to render even the harshest recordings into something detailed and musical.  The word "tizzy" is completely alien to the Torpedo III.  At the same time, the highs are even more extended and detailed than the Torpedo I.
> 
> ...


 

 MiniMAX for speakers, Torpedo for headphones. Got it. I was planning on buying next week, but it sounds like I may want to hold off a little and wait for this Torpedo III to debut.


----------



## JamieMcC

Do you think there might be a early bird promotion for those enthusiastic and patiently waiting?


----------



## Daveze

blze001 said:


> Quick question: aside from price, would there be any situations where the MiniMax would be preferred over the Torpedo? I'm looking to build a pretty solid amp to act as my audio centerpiece for the next few years while I build up a nice headphone collection. Am I correct in assuming the Torpedo is more flexible in terms of what headphones it'll work with?


 
  
 A situation that I prefer the MiniMax is for office listening. Australia is fairly strict on who can fiddle on the 240V (120V) side of the transformer (for anything at all), so the ability to have a tested and tagged 24V transformer means I can have my handbuilt amp in very safety conscious office environment. Based on a very short listen, I actually prefer my MiniMax to Torpedo for my Grado SR225 (what!? Sacrilege!) or maybe I wasn't as blown away by the differences between the MiniMax and the Torpedo (with the AKG 240 Sextett and Studio...Torpedo, no competition, truly mind blowing).


----------



## Blze001

Alright, turns out my patience couldn't hold out, I decided to go with the Torp I, especially since the Torp I was stretching my budget a little and the Torp III will cost a bit more on top of that. Still, it's not like the Torp I is the "wrong" choice and I can't wait to build it. Then I can start buying a plethora of headphones, since power won't be too much of a concern!
  
 In the long run, my wallet is going to hate this purchase.


----------



## UKToecutter

*what your wallet may hate your ears will love *


----------



## diego

I don´t think Torpedo III will substitute Torpedo I as they will have different sound signatures. Many people will probably want to keep both.


----------



## Blze001

The worst part about ordering a new hifi toy is waiting for it to finish processing so you can stalk it through the mail.


----------



## tomb

blze001 said:


> The worst part about ordering a new hifi toy is waiting for it to finish processing so you can stalk it through the mail.


 
 You will be able to stalk it first thing tomorrow.


----------



## Blze001

tomb said:


> You will be able to stalk it first thing tomorrow.


 
  
 *Sets up lawn-chair next to mailbox*


----------



## Blze001

blze001 said:


> *Sets up lawn-chair next to mailbox*


 
  
 I got the box on Monday.
  
 Two evenings, a burnt hand and a few creative curse words later, my Torpedo is singing away! 
	

	
	
		
		

		
		
	


	



  
 It may or may not have a slightly crooked tube, but I call that character. The important thing is there's no smoke, the house's circuit breakers are intact, my headphones didn't explode and I'm not hearing any oddities. Fingers crossed, but I think she works!
  
 I was really nervous plugging it in, this was my first high-voltage project and I had visions of smoke detectors going off and that lovely acrid smell of electrical smoke filling the house, but Tomb and Dsavitsk have made a largely idiot-proof kit here. I should know, I'm a pretty talented idiot.


----------



## tomb

blze001 said:


> blze001 said:
> 
> 
> > *Sets up lawn-chair next to mailbox*
> ...


 
  
  Dsavitsk is the _only_ reason I've been able to build high-voltage stuff.  I still do things like use a meter to measure the case to ground voltage after I've built a new one - before I touch it.  Dsavitsk knows what he's doing, though, and he's always Safety First.
  
 So, how's it sound?


----------



## Blze001

tomb said:


> Dsavitsk is the _only_ reason I've been able to build high-voltage stuff.  I still do things like use a meter to measure the case to ground voltage after I've built a new one - before I touch it.  Dsavitsk knows what he's doing, though, and he's always Safety First.
> 
> So, how's it sound?


 
  
 Fair warning, I'm still an audio newbie, so these are inexperienced observations.
  
 I was honestly shocked by the change. I knew my Q701s were under powered coming off my DAC directly, but they still sounded pretty stellar. I did notice a lack of low-end and some mids and treb frequencies sounded a little spikey. Just adding the Torp sounded like someone took a smoothing tool to the frequency graph: the few spikes I was hearing vanished and the spots where it was lacking seemed to come back a little and the whole thing felt fuller and warmer. I'm sure a lot of this is simply the Torp giving my headphones the power they crave, I know the Qs are more power-hungry than their specs would make you think, but I've always been able to tell when audio has a tube component and I can definitely hear the tubes in this.
  
 I'm going to run it the rest of the week on the 6J6s just to make sure there aren't gremlins hiding somewhere, then try the E90CCs... I want the cheap tubes in the line of fire if something goes wrong.


----------



## Pingupenguins

I was always a little irked by the Torpedo because of the fat warning that says "HIGH VOLTAGE". But glad they are sounding great on Dynamic driver AKG's! One of these days when I feel courageous enough I'll give the high voltage crowd a crack. Gotta start with the little stuff first though.


----------



## tomb

pingupenguins said:


> I was always a little irked by the Torpedo because of the fat warning that says "HIGH VOLTAGE". But glad they are sounding great on Dynamic driver AKG's! One of these days when I feel courageous enough I'll give the high voltage crowd a crack. Gotta start with the little stuff first though.


 
  
 Well, the biggest concerns were taken into account with Dsavitsk's PCB design.  No other high-voltage tube amplifier has such a complete PCB.  There is no wiring whatsoever except for the ground wire to the pot and the safety ground from the PCB to the case.  That takes away the biggest concerns in building a high-voltage amplifier - there is no wiring of high-voltage, anywhere.


----------



## Blze001

pingupenguins said:


> I was always a little irked by the Torpedo because of the fat warning that says "HIGH VOLTAGE". But glad they are sounding great on Dynamic driver AKG's! One of these days when I feel courageous enough I'll give the high voltage crowd a crack. Gotta start with the little stuff first though.


 
  
 Yeah, my 701s love the amp... my K550s don't really get a drastic boost from it, however. The background is blacker and there is a little less harshness, but otherwise my K550s run the same on the Torp as they do on my cMoy... then again, the K550s are half the impedance of the Q701s.
  
 To put in perspective the difficulty of this build, my experience with a soldering iron prior to this was a cMoyBB kit from JDS labs. That's it. Just take it slow and methodically, and it'll go together just fine. One trick I picked up: find a small alligator clamp and attach it on the component lead between where the lead goes through the PCB and the component itself, the clamp will siphon off a good bit of the heat, so you can stay on the spot a little longer and get a nice joint without worrying about torching the part. Not really needed for the little resistors, but some of the capacitors have seriously chunky leads and take a bit of heat to get the solder flowing properly.


----------



## Pingupenguins

tomb said:


> Well, the biggest concerns were taken into account with Dsavitsk's PCB design.  No other high-voltage tube amplifier has such a complete PCB.  There is no wiring whatsoever except for the ground wire to the pot and the safety ground from the PCB to the case.  That takes away the biggest concerns in building a high-voltage amplifier - there is no wiring of high-voltage, anywhere.


 
 Thats true. It's definitely a lot cleaner than some of the amp builds I've seen. Any comparisons vs the MiniMAX? I've been eyeballing that amp for about 2 years now.
  


blze001 said:


> Yeah, my 701s love the amp... my K550s don't really get a drastic boost from it, however. The background is blacker and there is a little less harshness, but otherwise my K550s run the same on the Torp as they do on my cMoy... then again, the K550s are half the impedance of the Q701s.
> 
> To put in perspective the difficulty of this build, my experience with a soldering iron prior to this was a cMoyBB kit from JDS labs. That's it. Just take it slow and methodically, and it'll go together just fine. One trick I picked up: find a small alligator clamp and attach it on the component lead between where the lead goes through the PCB and the component itself, the clamp will siphon off a good bit of the heat, so you can stay on the spot a little longer and get a nice joint without worrying about torching the part. Not really needed for the little resistors, but some of the capacitors have seriously chunky leads and take a bit of heat to get the solder flowing properly.


 
  
 I basically have the same experience. cMoy and GrubDAC. I've got a "3rd hand" from harbor freight that I use every day. Infinitely useful, I don't know what I would have done without it. Everyone who's any sort of DIY needs to get a "third hand".


----------



## tomb

pingupenguins said:


> tomb said:
> 
> 
> > Well, the biggest concerns were taken into account with Dsavitsk's PCB design.  No other high-voltage tube amplifier has such a complete PCB.  There is no wiring whatsoever except for the ground wire to the pot and the safety ground from the PCB to the case.  That takes away the biggest concerns in building a high-voltage amplifier - there is no wiring of high-voltage, anywhere.
> ...


 
  
 The MiniMAX is being phased out.  I only have 1 kit left.  You will find some that still prefer the MiniMAX for certain things (in this thread, even - just a few posts back).  However, the Torpedo I is superior.*  The parts count is much higher than the Torpedo.  It takes about 3-4 hours just to pack a MiniMAX kit.  I don't have the kind of time it takes to support that anymore.
  
  
 * Torpedo III may be in the Summit-Fi category with Cinemag OT's.


----------



## Pingupenguins

tomb said:


> The MiniMAX is being phased out.  I only have 1 kit left.  You will find some that still prefer the MiniMAX for certain things (in this thread, even - just a few posts back).  However, the Torpedo I is superior.*  The parts count is much higher than the Torpedo.  It takes about 3-4 hours just to pack a MiniMAX kit.  I don't have the kind of time it takes to support that anymore.
> 
> 
> * Torpedo III may be in the Summit-Fi category with Cinemag OT's.




I see. MiniMAX looked pretty fun imo. I also always liked the look and design of the amp. Never really was a fan of the long bodied torpedo on looks alone, but at the end of the day its also about sound quality. I feel like I've become more superficial over the last few years :/


----------



## Blze001

Well, my joy was short lived... now it won't turn on. I don't see any bad connections or anything, but the LEDs won't even come on...
  
 Before I go crazy with the soldering iron, are there any particular joints I should pay attention to? Tube sockets, certain capacitors, etc?
  
 EDIT: I did a quick re-melt on the tube sockets. It came back briefly, then went dark again.


----------



## OJNeg

tomb said:


> The MiniMAX is being phased out.  I only have 1 kit left.  You will find some that still prefer the MiniMAX for certain things (in this thread, even - just a few posts back).  However, the Torpedo I is superior.*  The parts count is much higher than the Torpedo.  It takes about 3-4 hours just to pack a MiniMAX kit.  I don't have the kind of time it takes to support that anymore.
> 
> 
> * Torpedo III may be in the Summit-Fi category with Cinemag OT's.


 

 Uh oh!


----------



## dsavitsk

blze001 said:


> Before I go crazy with the soldering iron




First thing to do is take pictures of both sides of the PCB so we can take a look.


----------



## JamieMcC

tomb said:


> * Torpedo III may be in the Summit-Fi category with Cinemag OT's.


 
  
 Where all right on the edge of our seats leaning forward 
	

	
	
		
		

		
		
	


	




needing more info are we talking Nickel, pin stripe? Come on share a few more details and some pics


----------



## tomb

dsavitsk said:


> blze001 said:
> 
> 
> > Before I go crazy with the soldering iron
> ...


 
  
 Ditto.  Let us help, if you can.


----------



## dsavitsk

jamiemcc said:


> are we talking Nickel, pin stripe? Come on share a few more details and some pics




Solid nickel.


----------



## Blze001

dsavitsk said:


> First thing to do is take pictures of both sides of the PCB so we can take a look.


 
  
 Turns out it wasn't the amp at all. On a whim, I moved the amp to a different outlet and plugged it in and it worked. Turns out my old surge protector's last socket had a wire loose.
  
 And that to my list of things learned: try a different outlet just in case.


----------



## tomb

blze001 said:


> dsavitsk said:
> 
> 
> > First thing to do is take pictures of both sides of the PCB so we can take a look.
> ...


 
  
 Good!


----------



## Pingupenguins

blze001 said:


> Turns out it wasn't the amp at all. On a whim, I moved the amp to a different outlet and plugged it in and it worked. Turns out my old surge protector's last socket had a wire loose.
> 
> And that to my list of things learned: try a different outlet just in case.


 

 Close call, lol!


----------



## Blze001

pingupenguins said:


> Close call, lol!


 
  
 I know, I got that ice-rock falling into the stomach feeling when I flipped the switch and nothing happened, glad it was something else that broke!
  
 Also, I'm impressed the amp can sit this close to computer without picking up any interference from all the electrical goings-ons inside. I'm guessing the tubes being mostly protected by the aluminum case helps?


----------



## tomb

Honestly?  I think you're lucky on that one (interference).  Put it on the top where the computer power supply is, and you'll probably get a lot. 
	

	
	
		
		

		
		
	


	




  In my experience, it's where the OTs are and how close they are to something that might cause interference.  Luckily, we usually have clearance around the business end of an amp, but if you put it on top of something that has line power or a transformer in proximity to those OT's, they'll pick it up.


----------



## Blze001

tomb said:


> Honestly?  I think you're lucky on that one (interference).  Put it on the top where the computer power supply is, and you'll probably get a lot.
> 
> 
> 
> ...


 
  
 Funny you should say that, but the powersupply is on the bottom of the case. It is, however, a small high-efficiency unit, so maybe the higher build quality results in reduced electromagnetic... leakage? Is that the right term? Also the high-voltage parts are towards the rear of the unit, so the OTs are about as far away from those as they are from the amp's own power transformer. My guess is it's elements of both. Either way, I'm glad it's the case, it simplifies my desk layout.


----------



## Pingupenguins

Would I be able to place my amp near my solder station? Don't have much room on the desk, so if interference is an issue with other devices being near by, I should probably ask....


----------



## dsavitsk

pingupenguins said:


> Would I be able to place my amp near my solder station? Don't have much room on the desk, so if interference is an issue with other devices being near by, I should probably ask....




The only way to know is to try it.


----------



## FishHead

Will you put a notice on this thread when you post the new Torpedo III build? 

Is there any new estimates (release date, cost, etc) that you can throw in the cage here?


----------



## tomb

fishhead said:


> Will you put a notice on this thread when you post the new Torpedo III build?
> 
> Is there any new estimates (release date, cost, etc) that you can throw in the cage here?


 
  
 PCB's are here and all parts except tubes.  I hope to get a line on those today.  Most likely, I'll go with new sets of JJ 12AU7's, mostly because they're cheap and new manufacture (better quality control).  The realm of 12AY7, 12AU7, and 12AX7 tone and esoterica is too large for me to compete as a tube dealer.  So, I'm not going to do anything but supply a basic pair with good quality control that works.  Either the JJ's or the EH's are probably the best way to do that.
  
 I hope to make a build-by-photo this weekend and will post something when I do.


----------



## OJNeg

tomb said:


> PCB's are here and all parts except tubes.  I hope to get a line on those today.  Most likely, I'll go with new sets of JJ 12AU7's, mostly because they're cheap and new manufacture (better quality control).  The realm of 12AY7, 12AU7, and 12AX7 tone and esoterica is too large for me to compete as a tube dealer.  So, I'm not going to do anything but supply a basic pair with good quality control that works.  Either the JJ's or the EH's are probably the best way to do that.
> 
> I hope to make a build-by-photo this weekend and will post something when I do.


 

 I take it the Edcor OPTs are going to ship with the Torp3? Any status update on Cinemag OPTs?


----------



## tomb

ojneg said:


> tomb said:
> 
> 
> > PCB's are here and all parts except tubes.  I hope to get a line on those today.  Most likely, I'll go with new sets of JJ 12AU7's, mostly because they're cheap and new manufacture (better quality control).  The realm of 12AY7, 12AU7, and 12AX7 tone and esoterica is too large for me to compete as a tube dealer.  So, I'm not going to do anything but supply a basic pair with good quality control that works.  Either the JJ's or the EH's are probably the best way to do that.
> ...


 
  
 The Cinemags will be an option once they are available, but keep in mind that they won't be cheap.  You'll have to wait for Dsavitsk to post for an update on those.
  
 I haven't heard the Cinemags yet, but the amp is already noticeably superior to the Torpedo I with the Edcors.  The difference is easy enough to notice in a couple of minutes or less.  For long-term listening - due to the nature of the DSHA portion of the circuit - it's much more superior than that.
  
 So, given the cost of the Cinemags, we feel that's there plenty of opportunity to offer both options.  The Cinemags would be a perfect opportunity for someone just starting out with the Torpedo III to buy low, then upgrade high later on ... or something like that.  I could be wrong, though.  It could work out that everyone will want Cinemags and we'll just save the Edcors for Torpedo I, assuming it will still sell, too.  These are all tricky questions from a business perspective - predicting customer reaction, etc.  Just to remind everyone, the proprietary nature of the ECP Audio circuitry involved will mean that the Torpedo III will cost a lot more, anyway.  I hope it doesn't shock everyone.
  
 Anyway, I have quite a bit of work to do before actually selling the kits - maybe a week or two, perhaps.  So, it's quite possible the Cinemags will arrive by that time.


----------



## OJNeg

tomb said:


> The Cinemags will be an option once they are available, but keep in mind that they won't be cheap.  You'll have to wait for Dsavitsk to post for an update on those.
> 
> I haven't heard the Cinemags yet, but the amp is already noticeably superior to the Torpedo I with the Edcors.  The difference is easy enough to notice in a couple of minutes or less.  For long-term listening - due to the nature of the DSHA portion of the circuit - it's much more superior than that.
> 
> ...


 
 TBH I'm more interested in putting the Cinemags in the Torp1


----------



## dsavitsk

ojneg said:


> Any status update on Cinemag OPTs?







ojneg said:


> TBH I'm more interested in putting the Cinemags in the Torp1




What we hope will be the final prototypes of the nickel OPTs should be here within the week. If all goes well with them, we will offer the T3 with either the Edcors or the Cinemags at different price points. I will also offer the Cinemags for sale on their own. As far as we know, they should work fine in the T1, but neither of us have tested that yet.


----------



## OJNeg

Thanks Doug


----------



## Blze001

I was inspired to go back to what got me interested in tube sound to begin with this weekend. Set up an FM transmitter and fired up my dad's old 1960's Grundig radio. Clearly, the Torpedo and headphones reproduce music better across the board, but there's something about jazz coming out of a non-hybrid tube radio in a wooden cabinet that just sounds right. 
  
 So what kind of changes to the sound could I expect to hear if I changed from the provided parafeed caps to, say, the Clarity Caps that Tom used? Not looking for a "better or worse", more a "this part of the sonic signature generally changes if caps are swapped".


----------



## OJNeg

blze001 said:


> I was inspired to go back to what got me interested in tube sound to begin with this weekend. Set up an FM transmitter and fired up my dad's old 1960's Grundig radio. Clearly, the Torpedo and headphones reproduce music better across the board, but there's something about jazz coming out of a non-hybrid tube radio in a wooden cabinet that just sounds right.
> 
> So what kind of changes to the sound could I expect to hear if I changed from the provided parafeed caps to, say, the Clarity Caps that Tom used? Not looking for a "better or worse", more a "this part of the sonic signature generally changes if caps are swapped".


 
 What sort of shift are you looking for exactly?
  
 With the Jantzen Silvers I have in my Torpedo things are just a lot more clear and energetic. I consider it a direct upgrade from the Solens (which aren't bad sounding, but can be improved IMO)


----------



## dsavitsk

ojneg said:


> What sort of shift are you looking for exactly?




I'll throw in that transformer changes are not like capacitor changes. With better caps, we think maybe we hear some subtle differences with better caps offering slightly better clarity, etc. There is some measurement evidence that different caps sound different, but it is fairly subjective and subtle. With transformers, the changes are large and easily measurable. The measurements below are from CH 15 f the Handbook for sound engineers https://books.google.com/books?id=t__vBgAAQBAJ&lpg=PA378&ots=vXxDOk2LAV&pg=PA367#v=onepage&q&f=false


----------



## Blze001

ojneg said:


> What sort of shift are you looking for exactly?
> 
> With the Jantzen Silvers I have in my Torpedo things are just a lot more clear and energetic. I consider it a direct upgrade from the Solens (which aren't bad sounding, but can be improved IMO)


 
  
 Not really a case of me looking for a shift, more me curious about how amplifiers work and my love of tinkering.
  
 So capacitors make small shifts depending on how big the gap in quality is, whereas output transformers will produce the kinds of instantly noticeable changes that changing tubes will? And the Cinemags will sound better than the Elcors because they have a higher nickel percentage and, therefore, less distortion?


----------



## dsavitsk

Capacitor changes make small differences. Sometimes these are worthwhile, but they are objectively small. Tube changes also make objectively small differences. Which is larger is hard to say -- depends on the particular parts. Transformer changes are larger than both because of the lower distortion due to different core material and because how different core material transforms different frequencies. The Cinemags will sound better because they have better material and because the winding technique is better. The Edcors offer extremely good sound for the money. The Cinemags offer extremely good sound.


----------



## OJNeg

I will agree with Doug. Capacitor rolling can give you a slightly different signature but with signal transformers the differences are more tangible. Once I'm able to put those Cinemags in my Torp1 I'll let you guys know in more certain terms


----------



## tomb

blze001 said:


> I was inspired to go back to what got me interested in tube sound to begin with this weekend. Set up an FM transmitter and fired up my dad's old 1960's Grundig radio. Clearly, the Torpedo and headphones reproduce music better across the board, but there's something about jazz coming out of a non-hybrid tube radio in a wooden cabinet that just sounds right.
> 
> So what kind of changes to the sound could I expect to hear if I changed from the provided parafeed caps to, say, the Clarity Caps that Tom used? Not looking for a "better or worse", more a "this part of the sonic signature generally changes if caps are swapped".


 
  
 This is not really a scientific finding or even one from elaborate experience, but I was never impressed with the Clarity caps.  I switched to the Solens for the kits because they either sounded the same or slightly better than the Clarity caps.  The fact that they were much cheaper was a tremendous bonus, but that was not the reason I started using them.  There are Solens in my own personal Torpedo I, not Clarity caps.
  
 The Torpedo III will come with Epcos box caps.  It's not for any particular reason except that Dsavitsk suggested them and I have no complaints whatsoever.  I've since learned that they apparently have a pretty good "sleeper" reputation.


----------



## dsavitsk

tomb said:


> I've since learned that they apparently have a pretty good "sleeper" reputation.




I used them because they were cheap and fit the board  Finding caps is a little tricky as this amp needs 4x 10u 300V caps. Very few audiophile caps will fit (each cap can be up to 21.5mm width/diameter and ~48mm in length if you want to go looking.) I think there is a Mundorf that will fit but I have not tried it. There is also the possibility of utilizing a small bypass (probably 1u or so as a starting point). Neither of us has tried this yet, but it is probably the best option for a cap upgrade. To make up for the lack of cap rolling, there are dozens of tubes that can be used


----------



## FishHead

Between Tunes, Caps, Headphomes and now Transformers I would hope to find the right combination eventually. I have been told it is the journey and not the destination which is important. 

Safe travels!


----------



## HiGHFLYiN9

Very exciting updates. I might ransack my Torpedo I for parts


----------



## dsavitsk




----------



## HiGHFLYiN9

Nice! Has the ECP logo on there too


----------



## JamieMcC

highflyin9 said:


> Nice! Has the ECP logo on there too


 

 ha ha I didn't  notice when I looked earlier, you just got to love those subtle little details...


----------



## dsavitsk

In addition to being used for the T3, these will also be available for DIY use.


----------



## diego

Can you share the specs and price?


----------



## dsavitsk

They are 10K:300 with a center tap on the primary and a 32 Ohm tap on the secondary. Unless nickel jumps again, I think they are going to be $225/pair.


----------



## FishHead

highflyin9 said:


> Very exciting updates. I might ransack my Torpedo I for parts




Didn't you do the steampunk one with the elevated tubes?


----------



## diego

dsavitsk said:


> They are 10K:300 with a center tap on the primary and a 32 Ohm tap on the secondary. Unless nickel jumps again, I think they are going to be $225/pair.


 
  
  
 What is the DCR and how much power can they handle?
 Diego


----------



## tomb

fishhead said:


> highflyin9 said:
> 
> 
> > Very exciting updates. I might ransack my Torpedo I for parts
> ...


 
  
 Yes, he did.  A magnificent build.


----------



## OJNeg

I'm guessing Doug is still running the Cinemag OPTs through the gauntlet. Any idea when the nickel will be ready for the plebs?


----------



## HiGHFLYiN9

tomb said:


> Yes, he did.  A magnificent build.


 
 Thanks Tom, wouldn't be remotely possible without you guys and your EXTENSIVE efforts.
  
 $225 seems pretty reasonable for the Cinemags. They're superbly made.


----------



## tomb

ojneg said:


> I'm guessing Doug is still running the Cinemag OPTs through the gauntlet. Any idea when the nickel will be ready for the plebs?




He estimated two weeks, but stuff like this can vary.

Meanwhile, I built another Torpedo III using the production PCB and the parts I'll be supplying with the kits. It's some of the best headphone listening I've had, even with the Edcors. I've spent several days going back through almost my entire music and headphone inventory for a re-listen. Even after all of that, my ears feel perfectly normal, which is actually unique in my experience.

I also documented the build, so I'll be working on web pages soon and maybe another build thread.


----------



## tomb

highflyin9 said:


> tomb said:
> 
> 
> > Yes, he did.  A magnificent build.
> ...




Thanks for the kind comments!


----------



## dsavitsk

ojneg said:


> I'm guessing Doug is still running the Cinemag OPTs through the gauntlet. Any idea when the nickel will be ready for the plebs?




They have been finalized and ordered. It is just a matter of waiting for manufacturing to be completed. Hopefully just a few weeks more. In the meantime Tom is finalizing the rest of the parts, the instructions, etc.


----------



## JamieMcC

Great stuff I am looking forward to the seeing the builds pics and a finished Torpedo III


----------



## Blze001

So here's a question: I have the chance to pick up a pair of Pioneer SE-305 vintage headphones for super cheap, but I'm really not sure how their 8ohm resistance is going to work with the Torpedo... you guys think there's a chance of damage to either?


----------



## dsavitsk

I don't think damage is a concern. But I don't know that it will sound great.


----------



## OJNeg

You definitely don't want that headphone with Torp 1. I'd guess Zout on Torp3 is lower and might be better match.


----------



## Blze001

Yeah, that's what I thought. It seems like those headphones should be driven by a speaker am with a 1/4" jack on it.


----------



## Misterrogers

Hey Doug - I'm thinking about picking up your L2 MB as a build over winter. Would I be correct to assume that the custom Cinemag OPTs would work with the L2 also?


----------



## Blze001

misterrogers said:


> Hey Doug - I'm thinking about picking up your L2 MB as a build over winter. Would I be correct to assume that the custom Cinemag OPTs would work with the L2 also?


 
  
 IIRC the L2 is discontinued. At least that's what I saw on his website last. Unless there's a different DIY section that I missed.


----------



## tomb

blze001 said:


> misterrogers said:
> 
> 
> > Hey Doug - I'm thinking about picking up your L2 MB as a build over winter. Would I be correct to assume that the custom Cinemag OPTs would work with the L2 also?
> ...


 
  
 He's still selling L2 PCB's.


----------



## dsavitsk

I do have L2 PCBs available and the new Cinemags will fit the boards (as will the Edcors) but frankly I'd build a T3 before an L2 unless one is a glutton for punishment. The L2 build process is non-trivial, and I like the T3 better anyway.


----------



## JamieMcC

How far away currently is the T3 from being available?


----------



## Misterrogers

Hmm, thanks Doug. T3 must be quite an amp - I've heard L2 a few times and really liked it. I'll take your advice though, T3 it is.


----------



## dsavitsk

If there are no more surprises, 2 weeks maybe.


----------



## FishHead

Two days left!


----------



## OJNeg

fishhead said:


> Two days left!


 

 What part of "maybe" don't you understand?


----------



## JamieMcC




----------



## dsavitsk

Nickel transformers have arrived -- I am listening to them right now. Now it is just a matter of getting the first batch to Tom and getting the site ready to take orders. Almost there.


----------



## FishHead

dsavitsk said:


> Nickel transformers have arrived -- I am listening to them right now. Now it is just a matter of getting the first batch to Tom and getting the site ready to take orders. Almost there.




What are your impressions as you listen to them?


----------



## dsavitsk

They sound just like the prototypes, which is to say they sound fantastic.


----------



## FishHead

It is always nice when a production run works the same as a prototype.


----------



## FishHead

Bump . Not that I am VERY interested and check every day or that I would admit to doing so.

Oops! Nevermind. 

http://www.head-fi.org/t/781651/torpedo-iii-build-thread


----------



## Misterrogers

The kit is available.


----------



## FishHead

dsavitsk said:


> Now available: https://squareup.com/market/ecp-consolidated-productions-llc/headphone-amplifier-parafeed-transformers-pair




Are the cinimags a viable upgrade for the T1? If so what would you project the difference being?


----------



## OJNeg

The ones my mate order just arrived. I should get a chance to hear it a bit.


----------



## heku

I made adapters for 6E6P tubes
  

  
 First I tried 6E5P tubes and liked how they sound, but heaters resistance was so low it triggered heater regulators overcurrent protection when tubes were cold.
 To get around this I turned amp on with one tube plugged in and let tube warm. Then turned amp off, plugged second tube in and turned amp on again.
 6E6P tubes dont have that problem and also sound good.


----------



## heku

I have also wired output tranformers as autoformers.
  
 First I moved primary GND tap to unused pin next to old pin.
  

  
 And then used jumper wires to connect it to 300 ohm pin.


----------



## OJNeg

Huh, interesting idea. Would you mind giving us a quick sketch of how you changed the XFMR wiring from the schematic view?


----------



## heku

From this


 To this


----------



## Eigenstated

Am I late to the party? 
Yeah well, I´ll try anyway. Bought the blue Torpedo a while back and want to do some of the tweaks, lots of hum; so I have some questions related to materials.
The BY228GP (DO-201AD) Rectifier 2.5A 20V, I can´t source these in Europe right now; I can get 1N 5822 Schottky Diode, 40V 3A DO201AD from banzai, can anyone give me a few tips?
The zener mod, I got zeners at home, 6.8 and 7.5v, not the one listed though. No RN60 resistors but ordinary 1% metalfilm at 430 and 470r. How crucial are the VDs?
I now it´s an old thread but it´s all I got, very appreciate of any help.
Some pics:


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