# eXStatA Build Thread II



## runeight

Starting this thread for all of the new builders who are getting eXStatA boards through the latest group buy.
   
  One piece of technical info for you new builders. On the website there is a fix to kill oscillation in the first beta run. This fix entails wiring two of the heatsinks to ground. A diagram is provided on the website.
   
  The new boards, however, already have this grounding built into the traces. All you have to do is to be sure to solder the two CCS heatsinks on each board to their pads. I'll try to add this info to the webiste.
   
  This applies only to the SS board. I recall that the hybrid board did not need this fix. But I may remember wrong. If so, then the fix is still to wire the heatsink pins to the ground point at the input terminal block.
   
  In addition, all of the heatsinks now have metalized pads so that you can solder them in place.
   
  In all other respects the new boards are the same as the original betas, all of which worked when built correctly.


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## HeadphoneAddict

Thanks Alex!


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## audionut

Alex, The hybrid boards need the heatsinks grounded, too, or at least mine did, to keep the amp from oscillating.


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## runeight

Shoot. I couldn't remember. 
	

	
	
		
		

		
		
	


	



   
  Well, sorry folks, those of you who got the hybrid boards, you'll probably have to wire the CCS heatsinks to ground. Several previous builders can help with this.


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## rbarth

Hello Gents.  I have populated everything on my PS board except for the C1 – C2 caps and the heatsink/transistor assemblies.  I need to ask a couple of questions about them before proceeding:
   
  (1)  Why are there two sets of mounting holes for the C1 and C2 caps?  I see on the underside of the board that the two negative holes for C1 and the two positive holes for C2 do not seem to lead to anywhere.  Anyway, does it matter in which sets of holes I mount these guys?
   
  (2)  I have collected most of the photos posted on the threads to help me with this build and see (I think) that the heatsinks on some of the PS boards have been shimmed before mounting:  i.e., there is a space between the bottom of the heatsinks and the top of the board.  Is that the way to go or should I mount them flush?
   
  (3)  Also, I understand that the WIMA caps do not have directional or orientation requirements for mounting.  (I hope I understand this right.)  If that’s the case, what are those “equal signs” printed on the board inside the outlines of where those caps are mounted?
   
  (4)  Finally (for now), I see that the BOM lists an R10 and R11 150K ohm resistor together with the R9 and R12 ones.  I found and mounted the R9 and R12s, but if there really is supposed to be an R10 and R11 resistor on my board, somebody’s gonna have to tell me where the holes for those critters are hiding.
   
  Thanks.


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## pabbi1

1) IIRC, there were differing pitches for C1/2 for different caps, and it makes no difference which set you use, so long as you get +/- correct.
   
  2) Those may be my heatsinks, and are just a function of the ones I used, where  the pins have a bit of a shelf to seperate them from the board. No real functional reason.
   
  3) Wima are indeed not polarized. Just a WAG, but maybe that "=" is just the universal symbol for capacitor (some labeling requirement)?
   
  4) Sorry, I don't have a current board.


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## rbarth

Thank for your response, Al.  I should have waited with my post, however, as I now have another question.  It's about the Q5, Q6 and Q7,Q8 transistors.  All four of them have some sort of ID printed on one side.  When I mount them to the heatsinks with this ID facing out (i.e., away from the surface of the heatsinks), their pins are too far apart to fit into the PS board.  If I reverse them and so that the printed ID sides are both facing towards the headsinks, their pins are too narrow to fit into the PS board.  (I checked this twice and believe I am right about this.)  So, how do these transistors get mounted? 
   
  EDIT:  Also about transistors.  The mounting surfaces of some are made entirely of plastic and the special washer that comes with the Aavid mounting kit does not fit into their mounting holes.  Should I place a regular flat washer between the screw and outside surface of these transistors?  Also, I believe I heard somewhere that you don't need to use the Thermasil pads between the insid" surface of these plastic transistors and the heat sink.  Is that true or should I use the pads no matter what?


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## pidesd

when you rotate 180 degrees a mje350,340 the distance between the pins is not supposed to change. look to see if you have the right part at it s right place on the board. pics would help.


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## rbarth

Quote: 





pidesd said:


> when you rotate 180 degrees a mje350,340 the distance between the pins is not supposed to change. look to see if you have the right part on it s right place on the board. pics would help.


 
  I ordered the parts straight off the BOM from Mouser and have double checked the part numbers.  So, I'm sure I have what was specified.  Do you want pics of just the transistors or mounted to the heatsinks to show the incompatibilities I'm talking about?  BTW, when you look at these transistors from the bottom, you can see that the pins are not connected to the body directly in the center.  They are more to one side.


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## pidesd

unless there is an error on the PCB or the mje350 is not an mje 350, it should fit., even if the pins are not centered. a picture of the transistor next to the pads might enlighten.


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## les_garten

Pictures just add to the FUN!


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## rbarth

Quote: 





pidesd said:


> unless there is an error on the PCB or the mje350 is not an mje 350, it should fit., even if the pins are not centered. a picture of the transistor next to the pads might enlighten.


 
  I'll be happy to post that but it probably won't be right away.  Thanks for your input. (The two Mouser envelopes definitely say MJE340STU and MJE350STU.)


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## pidesd

what is important is what the device look like not the envelopes.
   
  take your time for pictures. if this amp turns out to be a success, some of us will still be here to help (i hope) in a couple years


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## TimJo

There is no R10 or R11 - you are correct. 
   
  My memory is that an earlier version had them, but they where replaced by the zener strings in order to provide better regulation (Z3 thru Z8).
  
  Quote: 





rbarth said:


> (4)  Finally (for now), I see that the BOM lists an R10 and R11 150K ohm resistor together with the R9 and R12 ones.  I found and mounted the R9 and R12s, but if there really is supposed to be an R10 and R11 resistor on my board, somebody’s gonna have to tell me where the holes for those critters are hiding.
> 
> Thanks.


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## rbarth

OK, juggled some things around to be able to send these pics ASAP.  You can see in PIC1, shooting straight down and aligning one set of pins directly over the holes that the other set of pins are too wide to fit.  If I were to turn each transistor 180 degrees and mount it that way, the pins would be too narrow.  In PIC2, you can see how the pins themselves are mounted off-center to the transistor.  This is Mouser Part No. 512-MJE340STU.  PIC3 shows the part, which has “FY K39 MJE340” printed on it.
   
  Now, my son got involved, bent the pins and was able to subsequently insert this transistor/heatsink assembly into the board.  This was done with the printed ID material to the outside on both transistors, away from the heatsink.  Is this OK?  Is this, in other words, the right orientation and is bending it like this OK?  (I hope I haven’t made a big deal out of nothing.)


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## TimJo

Re: the thermasil pads - yes you should use them even though the transistors have a plastic body. They help transfer the heat from the device to the heatsink.
   
  Use a flat washer between the tran and the lock washer & nut.
   
  Starting towards the side next to the big WIMA caps, it should be a sandwich as follows:
   
  screwhead
  transistor
  pad
  heatsink
  pad
  transistor
  flatwasher
  lockwasher
  nut
   
  NOTE: Don't mount C3 & C4 until after you get the trans and heatsinks in place, or it may be difficult to keep the screwhead from spinning when tightening the sandwich of parts.
   
  As far as orientation of the trans goes, you need to pay attention that the dot on the transistor is on the same side as the little dot on the silkscreen.  
   
  Quote: 





rbarth said:


> Thank for your response, Al.  I should have waited with my post, however, as I now have another question.  It's about the Q5, Q6 and Q7,Q8 transistors.  All four of them have some sort of ID printed on one side.  When I mount them to the heatsinks with this ID facing out (i.e., away from the surface of the heatsinks), their pins are too far apart to fit into the PS board.  If I reverse them and so that the printed ID sides are both facing towards the headsinks, their pins are too narrow to fit into the PS board.  (I checked this twice and believe I am right about this.)  So, how do these transistors get mounted?
> 
> EDIT:  Also about transistors.  The mounting surfaces of some are made entirely of plastic and the special washer that comes with the Aavid mounting kit does not fit into their mounting holes.  Should I place a regular flat washer between the screw and outside surface of these transistors?  Also, I believe I heard somewhere that you don't need to use the Thermasil pads between the insid" surface of these plastic transistors and the heat sink.  Is that true or should I use the pads no matter what?


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## TimJo

Looks like we posted at the same time. 
	

	
	
		
		

		
			




   
  Okay, things look good. Bending pins is fine.
   
  What's important is the orientation of the part is correct with regards to the dots on the part and the dots on the silkscreen.


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## rbarth

Very, very helpful..  Many thanks.  (C3 and C4 are already mounted but I should be OK with a pair of needle nose pliers holding the screw while I tighten the nut.)  So, I can finish the PS.  On to the amp!


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## runeight

Yes, lettering to the outside and away from the heatsinks. You don't need the pads for plastic devices but if you don't use it then you need the thermal grease. Don't use the shoulder washer on the all plastic parts.
   
  Sorry about the R10/R11. These indeed went away and are still in the BoM.
   
  The two sets of pads for C1/C2 are to give you some choice for the lead spacing and size of these caps. Just use the pad spacing that fits with the caps you have.
   
  Looks like you are just about finished. When you mount the mosfets pay attention to the leads of R1/R3/R5 and make sure that they are not contacting the heatsink. Push them away a little if you need to.
   
  Edit: I see that my response is a little bit late.


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## rbarth

If I align the dots on the transistors so that they are on the same side as the little dot on the silkscreen, the printing on Q5, Q6, Q7 and Q8 is facing the heatsink, not away from it.  I can only see one dot on each transistor, which is on the side opposite the printing on the upper left hand corner.  So, I guess I'm still confused.  Right now, the transistors are mounted with the printing facing the heatsinks.


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## runeight

Yes, this is correct. Printing away from the heatsinks. Smooth side to the heatsink.
   
  Check the MJE data sheets if you're not sure.


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## runeight

Maybe this will also help.
   
  If you look at the devices from the bottom you'll see that the pins are closer to one side than the other. At least the should be.
   
  The side that is farther away from the pins should be the blank side of the plastic and this goes against the heatsinks.


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## rbarth

Thanks Alex.  That makes it crystal clear.


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## TimJo

Sorry if I added to the confusion.
   
  I'm back at my computer now and after googling the datasheet, I see the emitter doesn't have a dot. That's what i get for going on memory. 
   
  Glad to see you have it sorted out. Just wait 'till it starts making music!


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## rbarth

Not at all a problem. All is well now.  On to the amp!


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## runeight

Does this mean that your PS is up and working? Or just assembled?


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## rbarth

It's just assembled. My thought was to do all of the construction first and then return to the PS. Would you prefer that I test it first?


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## runeight

No. I just like hearing about when things work. Take your time.


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## pidesd

-


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## pidesd

nothing


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## rbarth

Hello again,
   
  I am now matching J271s prior to populating my amp board.  Unfortunately, it is not yet obvious to me how to test for IDSS from a schematic and so, in my search for a guide, came across Tangent’s  instructions at  http://tangentsoft.net/audio/opamp-bias.html  ( bottom of page), which I followed.   Below is a pic of my matching setup.  I am using a brand new Energizer A23 12V battery with the positive side connected to the jumper.  When I measure, I connect the positive lead of my DMM to the JFET’s drain and the negative lead of my DMM to the negative side of the battery.  I am certain that my DMM leads are connected properly to the meter and that the meter's settings are correct.  However, I’m telling you all of this because I'm surprised at my results and so wonder if I've done this right. Out of 20 J271s, I only have 6 whose IDSS measured above 10.  Their readings are:  20.75, 14.18, 12.76, 12.72, 11.13 and 10.48.  (I subsequently used the second new battery that came in the pack to do another reading of all of JFETS.  The results were all very close to the first readings --  generally within  5 to 15 one hundredths of a milliamp.) 
   
  So, gents, am I good to go with 12.76 and 12.72 on one side and 11.13 and 10.48 on the other?  Or have I done something wrong to get so many low readings?
   
  Thanks.


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## pidesd

that seems ok. datasheet says the idss range is 6 to 50 ma. also when you test the jfet the gate must be conneced to the source. dont know if you have done that properly. just be careful not to blow them because it s your only quad from what i can tell.
   
  also there is a very good website i use sometimes, full of informations: 
	

	
	
		
		

		
			




   
  http://www.cavalliaudio.com/exstata/main.php?page=matching


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## runeight

The fets need to be matched better if you want the two channels to have similar gain. Not absolutely necessary, but would help unless you are using two separate volume controls.
   
  It is useless, of course, to say that generally with 20 fets I get one good set. But, statistically, your result has some probability.


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## rbarth

Thanks.  I will buy more to get a better match.


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## rbarth

My additional J271s will arrive tomorrow.  In the meantime, I have a couple of unrelated transistor questions pertaining to my amp board:
   
  (1)  On the board, the sides of the outline for Q3 and Q4 show a taper.  The parts also have an ever so slight taper to them.  If I use this as my guide to insert these transistors, the printing on them is on the opposite side of the wider white line that indicates the width on the outline on the board.  Yes?  No?
   
  (2)  Opening up my package of Q11-12-13-14s woke me up faster than my cup of coffee this morning.  The Mouser P/N printed on the envelope is identical to what is specified on the BOM:  512-KSC5042FYDTU.  Fairchild’s P/N, also printed on the envelope, says KSC5042FYDTU.  But – these transistors do not have their three pins aligned in a row as the board indicates.  Rather, when you look up at them from below, you see that the pins form a triangle:  all three pins come out of the body the same way, but then the center pin bends out and then down.  The printing on the transistor says C5042F and then J11 below that.
   
  Finally, since I’m posting (I’ll try to shorten these things in the future), let me ask one more question, please:  Does the heatsink wiring image on the eXStatA website apply to my hybrid amp?  If yes, am I right in saying that you simply connect two wires to the heatsink pins from underneath the board and run them to the ground of the terminal connector?  If this isn’t right, what should I do to ground my heatsinks?
   
  Many thanks.


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## rbarth

Nearly an hour on the phone with Mouser has answered my question #2 above.  KSC5042FYDTU came to me from Mouser in the shape I described because a customer ordered 5,000 in that configuration and Mouser has some extras that they are passing on to a guy like me to get rid of their inventory.  The reason I didn’t get the straight-pinned version is because the part is now obsolete in all of its forms: http://www.fairchildsemi.com/obsolete/obs_result.jsp
   
  Mouser shows limited stock on hand:  67 pieces of KSC5042FTU (not the version specified on the BOM but the same transistor) and 56 pieces of the KSC5042FYDTU that I got.  The tech I spoke to (whose comments and manner inspired confidence in me) is not sure whether the “FTU” also has the triangular configuration on the pins.  (TU just refers to the packaging =  “tube”), but he is certain that both are the right transistor and was confident that if I were willing to straighten out that center pin to resemble the shape of its neighbors I’d be good to go.
   
  I apologize for not having checked this out before posting the above.  Hope no one has been inconvenienced.   (Still need an answer to my other two questions, guys.)


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## rbarth

My mother used to tell me, “Look before you leap!”  Apparently she knew me very well.  I have found among the photos I have collected one with sufficient resolution (by the designer, no less) that clearly shows that the orientation of the Q3 and Q4 transistors do indeed go on the board the way I asked about above.  Sorry again, gents.  Guess I only need the answer to my heatsink question.


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## TimJo

#1 - Yes. The tapers should match up.
   
  I grounded my heatsinks exactly as you described.
   
  That's interesting about the other transistors. Sounds like they will run out soon then...
  
  Quote: 





rbarth said:


> My additional J271s will arrive tomorrow.  In the meantime, I have a couple of unrelated transistor questions pertaining to my amp board:
> 
> (1)  On the board, the sides of the outline for Q3 and Q4 show a taper.  The parts also have an ever so slight taper to them.  If I use this as my guide to insert these transistors, the printing on them is on the opposite side of the wider white line that indicates the width on the outline on the board.  Yes?  No?
> 
> ...


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## runeight

Yes, the triangular pad shape is standard now, but it is very easy to straighten the middle pin into alignment with the other two. I think most everyone has had to do this and all works ok.
   
  I probably should have changed the pad spacing on this new rev but I didn't think of doing so.
   
  The heatsinks that you want to ground are the ones where Q11/Q12 are attached as in the diagram.
   
  On the SS board, even though the ground traces are built-in, you still have to solder the heatsink pins to their pads to make this work right.


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## rbarth

Here are the results/groupings of my “good” IDSS measurements after getting my second shipment of J271s.  (My son will be building an SS eXStatA and, in light of the poor results I got from my first set of 20, I went ahead and ordered an additional 50 to ensure we would both have really good matches.)
   
  10.00, 10.11, 10.29, 10.34, 10.39, 10.40, 10.51, 10.52, 10.56
  11.09, 11.11, 11.12, 11.36, 11.98
  12.40, 12.72, 12.84, 13.27
  20.34, 20.39, 20.41, 20.75
   
  So, how do I pick from these?  Is a higher IDSS better?  Or, are those J271s whose IDSS values vary the least across four pieces better?   Also, are there any guidelines or rules for how to select which should be Q1L, Q1R, Q2L and Q2R once the quad is chosen?


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## Beefy

Many excellent potential quads in there. I would go for the 10.29 through 10.40 and the 11.09 through 11.36.


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## BoilermakerFan

Just one amp?  I'd grab the quad of 10.39, 10.40 / 10.51, 10.52 and pair them that way. 
   
  Sell off a couple of the other close quads like the 11.09, 11.11, 11.12, 11.36.  I know a peep who could use them.  I'll have him send you a PM.


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## runeight

If it were me, I would take the ones in the 20s and then the 12s.


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## rbarth

I would like to learn as well as just build this amp.  Why the 20s and then the 12s?


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## TimJo

Well, Alex can chime in here with his reasoning, but _I think_ it's because the jfets are the principal component providing gain in this design. Again, _I think_ the better the idss of the jfet, the better the transconductance. On the matching page Alex recommends 10mA is the absolute minimum.


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## bidoux

Do you mean "the more IDSS" ? Better can be lower, it depends on what you plan to build.


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## runeight

Quote: 





> Well, Alex can chime in here with his reasoning, but I think it's because the jfets are the principal component providing gain in this design. Again, I think the better the idss of the jfet, the better the transconductance. On the matching page Alex recommends 10mA is the absolute minimum.


 
   
   
  Yes, that's the reasoning.


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## rbarth

I built a wooden case for my eXStatA but can’t tell from the pics of other wooden cases how the grounding should work. The only metal in the case is a 1/8” thick perforated aluminum base.  Can/should I star wire the ground to this?  Also, the pics of some wooden cases that also have perforated metal bases show another, usually smaller solid metal plate mounted above it on which the boards, transformer, etc. are connected with spacers.   Is this just because it’s easier to drill precise mounting holes and make connections on a solid metal plate or does this second, solid plate serve some other function?
   
  Also, if I set up/test  the power supply outside of the case, what do I connect the ground tab on the IEC inlet to?  And, is a 1 amp 250 volt slow blow fuse the right one for the switch specified on the BOM?
   
  Thanks.


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## pabbi1

Here are a couple extra pics of my current amp... you can see the earth ground just bolted to the plate with a just the PSU ground.


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## TimJo

Quote:


rbarth said:


> Also, if I set up/test  the power supply outside of the case, what do I connect the ground tab on the IEC inlet to?  And, is a 1 amp 250 volt slow blow fuse the right one for the switch specified on the BOM?


 

 You can just connect it to the star ground on the connector between C3 & C4. 
   
  When you do test the PS, just don't forget to connect the dummy load resistors! 
   
  And beware that they get screaming hot - hot enough to melt the tips of my clip on DMM leads. 
	

	
	
		
		

		
		
	


	



   
  Oh, and a 1 amp slo-blow should be just fine....


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## BoilermakerFan

Quote: 





timjo said:


> Quote:
> 
> You can just connect it to the star ground on the connector between C3 & C4.
> 
> ...


 

 Time to upgrade to Silicone jacketed tips!


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## Beefy

Quote: 





boilermakerfan said:


> Time to upgrade to Silicone jacketed tips!


 


 I sat my dummy loads on top of two 440x90x4mm pieces of aluminium (weighing two pounds) to help soak up the heat. The resistors still broke 100C


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## rbarth

On the website, after the Power Supply Setup instructions tell you to set P1 and P2 to their halfway positions, it says to do all of the rest as quickly as possible so as not to overheat the transistors in the regulator.  Several bullets down from this, it tells you to measure T1 and T3 after the rails have "eventually stabilized".  So, can somebody give me an idea of how long it should take for the rails to stabilize so that I know what to expect? 
   
  Also, should I measure each rail by touching my probes to the exposed wires coming out of the terminal connector or can I measure this by touching the screws on top?
   
  Finally, the Keystone Test Points specified in the BOM seem too big to plug into any of the “T” or  “Bias” ports on the board.  So, just stick the probe into them, right?


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## runeight

I think the website needs some changes. If the load resistors are connected you can take as long as you need to set the biases. I'll try to fix this soon.
   
  The test points do fit if you squeeze them together before pushing into the hole.
   
  You can measure by touching the screws on top.


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## rbarth

Well, gents, my PS is up and running!  My rails read +304.9 and -301.8 after adjusting P1 and P2.  Measuring T1 and T3 with respect to ground gives me readings of +313.5 and -311.3 – obviously not greater than +/- 320V.  So, am I in trouble or are these readings OK?
   
  The power LED works fine and the high bias has been set to 580 for my Stax 404LEs.  I have no low bias headphones.  Right now that reading is 195.  I’m assuming it’s OK to just leave it at that.
   
  My son is certain he hears a faint hum that I cannot detect even with my ears nearly touching the PS and the transformer (with all air conditioning and other household noisemakers turned off).  If my son is right, should I be concerned?


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## runeight

Great.  It would be better to have over 320V, particularly since your + rail is almost 305V. But there is still 8-9V across the mosfets and this is good enough.
   
  The biases don't care where you set them. 
	

	
	
		
		

		
		
	


	



   
  If the hum is the transformer, this is normal. If the hum is from the board, it may or may not mean anything.
   
  Try the amps first and if they are quiet then you can probably ignore the hum.


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## pabbi1

AC beat me to it...
   
  What tranny are you using? The Hammond and Triads can make some noise, and depending also how they are mounted. But, I had some hum-a-saurus Triads in a Sun case that had all sorts of vibtratory noise, that never came through the amp... YMMV.


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## runeight

Meant to ask, which transformer are you using?


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## rbarth

I’m using a Hammond 269JX.  It has, among other things, the following printed on the top: 
   
  PRI:  WHT-GRY: 115V 60HZ
  PRI:  WHT-BLK: 125V TAP
   
  I called Hammond about this and the tech told me that it was a newer model that was being offered because people around the country were complaining that their house current was higher than 115VAC.  I measured mine in several places and it was consistently over 120VAC and so I used the BLK live and WHT neutral connections.
   
  I asked my son if he could tell where his hum was coming from and he wasn’t sure.  I’ll ask him to listen again later today to see if he can tell whether it’s from the transformer or the PS.  One other thing about this:  Al, you mentioned how the PS was mounted.  Right now it isn’t.  It’s sitting unattached directly on top of a 1/8” thick perforated aluminum base inside a wooden case.  I intend to mount the boards and transformer on 1/8” thick solid aluminum plates with 3/4” plastic spacers and screws and then mount the solid aluminum plates to the perforated base with 1/2 “aluminum spacers and stainless steel hardware.  IF there is a hum, could it be caused by the perforated aluminum base that the PS and transformer are now sitting on?  (Ground from the IEC is connected to the center terminal on the PS where the dummy load resistors are also grounded.  Nothing is connected to the base.)


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## Beefy

Quote: 





rbarth said:


> My son is certain he hears a faint hum that I cannot detect even with my ears nearly touching the PS and the transformer (with all air conditioning and other household noisemakers turned off).  If my son is right, should I be concerned?


 

 Erm, please don't stick your head too close to the high voltages.

  
  Quote: 





rbarth said:


> I’m using a Hammond 269JX.  It has, among other things, the following printed on the top:
> 
> PRI:  WHT-GRY: 115V 60HZ
> PRI:  WHT-BLK: 125V TAP
> ...


 

 If you were to use the Wht-gry connections instead, that would boost your T1/T3 voltages.


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## runeight

Yes, this would be the right thing to do.


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## rbarth

OK, so it's desoldering time.  Happy to do so, actually, as it seems that I will be close to +/- 320V with the WHT-GRY connection.  Thanks.
   
  (I will watch my head, Beefy....)


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## pabbi1

You might just be hearing some vibration because the tranny isn't bolted down. I use the McMaster-Carr PVC mounts, but any dampening should be fine (teflon or fibre washers, etc), but I bet when everything is bolted down, you won't hear it.


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## rbarth

Yesss!  You guys are good.  With the WHT-GRY 115V 60HZ connection, I now have the following  readings:  Rails are +306.3 and -303.0.  T1 is +351.2 and T3 is -349.6.  Thank you very much! 
   
  So, why is there an increase in these values when using less voltage from the transformer?
   
  My son is certain now that his hum (I still can’t hear anything) is coming from the transformer.  So, I guess we’ll wait and see what happens once it’s bolted down and the amp is connected.


----------



## Beefy

Quote: 





> Originally Posted by *rbarth* /img/forum/go_quote.gif
> 
> So, why is there an increase in these values when using less voltage from the transformer?


 

 Transformers work as on 'fixed' ratios of how much they change the voltage.
   
  A transformer with a 125V primary and a 250V secondary will increase the voltage 2x. So if your line voltage is 120V you get 240V out.
   
  A transformer with a 115V primary and a 250V secondary will increase the voltage 2.17x. The same 120V line voltage becomes 261V out.


----------



## rhester

Where did the stax connectors get sourced from or were they a custom bui;d?


----------



## ujamerstand

http://www.vacuumtubesinc.com/Products/SocketsAdaptersParts/NewOldStockTubeSockets.aspx
   
  I'm guessing the 5-pin version would work? Otherwise you could try to contact woo audio for their jack.


----------



## pabbi1

The teflon and gold pin connectors were definitely a custom build from Luvdunhill, and Kerry has emulated this somewhat.
   
  I have 22 of the original Amphenol connectors (now made by WPI) which I 'found' after shipping all the tubes while looking for some other parts. These were graciously donated by Frank Cooter, and I will pass them on (limit 2 each)... SHOULD have sent a pair with all the tubes, but had honestly forgotten these.
   
  My (very) bad.
   
  Please PM me for the connectors - but, customs forms really, really suck.
   
  Again, my bad guys.


----------



## neob

Can you suggest another connector (brand, type and where)?
   
  Can I still buy custom connector from Luvdunhill as you mentioned above?
   
  Thanks


----------



## Forte

Quote: 





neob said:


> Can you suggest another connector (brand, type and where)?
> 
> Thanks


 
   
   
  These two look to be correct 
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=7190012&MPN=78-S6S&R=7190012&SEARCH=7190012&DESC=78-S6S
http://www.surplussales.com/Connectors/Microphone-6.html   (6 pin version at bottom of page)
   
  I emailed www.vacuumtubesinc.com and they are out of stock and don't know if or when they will have them again.


----------



## pabbi1

Those are correct - if you can source locally, that is your best bet. Looking at a package to OZ (and East) if we can work out logistics of a single ship from here. I have about 16 left, as of this morning, and will hold all other requests until we sort the Oz builders, as they asked first, and I should have sent some there with the tubes.


----------



## neob

I believe that you have sent my tubes... 
	

	
	
		
		

		
		
	


	



   
  If you have not sent my tubes yet, i'll be so glad to get the connector from you.


----------



## rbarth

I am now wiring and need some help with the following:
   
  (1)  I understand that the positive and negative signals connect to the input pins on the pot and then go from the output pins on the pot to the corresponding terminal blocks on the amp board.  What I’m not getting is how to connect the two input ground wires coming from the XLRs to the common pins on the pot and then to the two input ground terminals on the amp board. (I’m using a quad pot so obviously there are four common pins.)
   
  (2) There is an fourth, unnumbered pin on the XLRs that I’m also uncertain about.  Is this the ground for the XLR connector?  If yes, where I do ground it to?


----------



## runeight

Are you using two 3-pin xlr connectors? Or 4-pin jobbies?
   
  If 3-pin there is a wiring diagram on the exstata website that shows this wiring.


----------



## rbarth

I used the one specified on the BOM   It has three pins in a triangular shape numbered 1, 2 and 3 and one smaller, unnumbered tab on top of them that has a small hole in it.  I have checked the wiring diagram and regret to say that I am not experienced enough to determine whether the answer to my question is there.  I have never wired a balanced connection before.  In the past, I have wired the ground from the inputs to the the pot I was using and then ran it from there to the amp board.  Is this the same case with balanced inputs?  If yes, I have two ground wires and four common tabs on my pot.  How do I connect this?


----------



## pabbi1

Ok, sending 15 Stax connectors to Oz, with 4 passing through (2 to Bangkok for Chinsettawong, and 2 to Indonesia for noeb). Hope that will be enough, but...
   
  .. there __may__ be more free connectors available, so there should be plenty for everyone.
   
  I'll follow up on this tonight (can't get email during the day).


----------



## runeight

Quote: 





rbarth said:


> I used the one specified on the BOM   It has three pins in a triangular shape numbered 1, 2 and 3 and one smaller, unnumbered tab on top of them that has a small hole in it.  I have checked the wiring diagram and regret to say that I am not experienced enough to determine whether the answer to my question is there.  I have never wired a balanced connection before.  In the past, I have wired the ground from the inputs to the the pot I was using and then ran it from there to the amp board.  Is this the same case with balanced inputs?  If yes, I have two ground wires and four common tabs on my pot.  How do I connect this?


 

 OK. I can help, but it might have to bit later. Hang on.


----------



## rbarth

I really appreciate that and would be happy to hang on as long as necessary.  BUT:  I've decided at this 11th hour to add the 4PDT switch and RCA connectors.  So, if that changes things (I assume it will), I can get back to you when I have these added parts installed on my case -- probably in a few days in light of my current schedule.


----------



## studeb

Go to cavalliaudio.com > wiring > input wiring
   
  There is a image there showing how to wire up the switch with an SE and a balanced input for a single channel
   
  I agree the unnumbered tab on your XLR jack is a grounding tab for the connector/shield of the XLR plug. You do not need to do anything with that for now, or you can ground it to the star ground. Check to see if your source has a grounded plug, or you may generate a ground loop.


----------



## paxeaxe23

Thanks Alex for the Hybrid boards. I'm actually on holiday so won't start building till the end of August, but I have a question regarding use of a stepped Attenuator.
   
  I have two 4 deck 24 step "make before break" rotary switches similar to the ones that you see when googling "vishy Dale Stepped attenuator"  I Could use a ladder design, but I am considering building it as a balanced stereo attenuator and would then need an 8 deck switch if I wanted to go down that route. SO... I am wondering if I could build it as a shunt Attenuator.
   
  Any thoughts on the pros and cons between Balanced/single-ended Ladder/shunt ?
   
  Which of the two routes is likely to give the best result. I do intend to use good quality resistors and am ignoring the price difference and work involved with double the number of resistors to stuff onto the ladder version.
   
  Or should I talk to Beefy about his solution!
   
   
  Francis
   
  [edit: with two 4 deck switches I suppose I could build both versions, but that would be a lot of soldering!]


----------



## Beefy

Quote: 





paxeaxe23 said:


> Or should I talk to Beefy about his solution!


 
   
  That sounds like a really bad idea.
   
  *
   
  If you have a 4-deck attenuator, just build it series and use one of them. IMHO, the drawback to steppers is the granularity between steps, while series vs ladder/shunt is just e-peen.


----------



## paxeaxe23

Thats interesting. I'll try one in series and mount it into my SS amp when I get home and see if its any better than my ALPS Blue (which is only SE of course.) Not really had a lot of experience with the different options for stepped Attenuators, so thanks for the input!. I have been getting a lot of "stick" from my audiophile buddys about steppers and they all say under 48 steps is no use, but I have noticed that I only use a very small range on my SS amp and reckon if I calculate the steps right I can give myself a fairly good set of steps to listen with comfortably and safely!  I still have a spare ALPS if it all goes pear shaped. My main aim is to build the Hybrid Balanced all the way! Then I'll have to build a Balanced DAC.


----------



## Beefy

Quote: 





paxeaxe23 said:


> Thats interesting. I'll try one in series and mount it into my SS amp when I get home and see if its any better than my ALPS Blue (which is only SE of course.) Not really had a lot of experience with the different options for stepped Attenuators, so thanks for the input!. I have been getting a lot of "stick" from my audiophile buddys about steppers and they all say under 48 steps is no use, but I have noticed that I only use a very small range on my SS amp and reckon if I calculate the steps right I can give myself a fairly good set of steps to listen with comfortably and safely!  I still have a spare ALPS if it all goes pear shaped. My main aim is to build the Hybrid Balanced all the way! Then I'll have to build a Balanced DAC.


 


 I probably agree with your buddies, because I can't imagine myself ever using a default DACT, for example. Consider my M3, which is set at a gain of 2 (the lowest it can feasibly go) and I never go higher than 1/6 of a pot rotation. That would be just 4 steps for the whole range of what I listen to, and I would be literally stuck between steps 3 and 4.
   
  But a custom jobbie could be very useful.


----------



## pabbi1

Ya mean, like one of these (yes, two different units):
   

   
   

   
http://home.swbell.net/pabbi/Atten_chart.jpg
   
  Only 42 steps, but, whatever.
   
  Ok, Oz and Far East (Thailand, Indonesia, etc) ping me and let me know who needs Stax jacks - I have 15, with more incoming (graciously being provided by a fellow builder), so if 15 are enough, I'll send them now... if not, it will be a week or so. I'd like to send one package with customs forms.
   
  Canada guys, I'd like to send one package there as well, if need be.
   
  The tubes FS are all enroute - let me know of success (or failure - occasionally a tube doesn't quite make it intact).
   
  Finally, where the heck are the builds - needs to be some fire in the hole!


----------



## gilency

are the parts list in Cavalli audio updated or does anybody have a newer SS parts list?
  Better yet, does anybody have a parts list with the mouser or digikeys numbers?


----------



## ujamerstand

Quote: 





gilency said:


> are the parts list in Cavalli audio updated or does anybody have a newer SS parts list?
> Better yet, does anybody have a parts list with the mouser or digikeys numbers?


 

 The parts lists are outdated? But I built a BOM already!


----------



## gilency

sorry. Did not imply they are. I am merely asking if they are the ones to use or whether somebody has one with the Mouser or Digikeys list.


----------



## runeight

The excel BoMs on the website have part numbers, mostly from Mouser. They should be fairly current. Is this what you were asking?


----------



## gilency

yes. thanks.


----------



## rbarth

I got ahead of myself when I raised the subject of input wiring last time and need to put that on hold as I am having a problem bringing up my amp.  There is no smoke when I turn on the PS but the tubes don’t go on.  I left the power on for about five minutes and there was no glow at all. The amp is getting power, however:  -300 rail is measuring -170VDC; +300 is+ 420VDC.  All eight heater terminals are measuring between 168 to 170VDC.  P1 and P2 are not adjusting the offsets because the tubes are not working.  The tubes were advertised on eBay as a matched quad set of GE 6S4As.  Could they all be bad?  Any ideas?  If pictures would help I can post them early tomorrow.


----------



## pabbi1

Good pics would help, for sure.


----------



## TimJo

Just curious, but what are they measuring in AC? No glow sounds like no power to me. 
  
  Quote: 





rbarth said:


> there was no glow at all. All eight heater terminals are measuring between 168 to 170VDC.


----------



## runeight

Yes, that would be my question. Are you supplying heater power for the tubes?


----------



## runeight

Also, don't let the system run very long if the tubes are not lit.


----------



## runeight

Also, do you have RH1 and RH2 on the board?


----------



## rbarth

RH1 and RH2 are on board.  AC measurements for the two output terminals are .10mA and .08mA.  Output terminals to ground are .12mA AC and .11mA AC. (Please excuse the sloppy wiring.  Things will be much neater after I'm up and running.)
   
   .


----------



## TimJo

Yeah, it's your heater wiring. 
   
  Don't fire the amp up anymore until we help you rewire, because it'll hurt the tubes if the heaters aren't on.
   
  Give me a second and I'll see if I can describe how to wire the terminal block for the heaters...


----------



## Beefy

And the grounding doesn't look right either......?


----------



## BoilermakerFan

Each heater terminal block needs one leg of the heater secondaries.  As it's wired now, you have only one side of the heater winding coming in to each tube.
   
  http://www.cavalliaudio.com/exstata/images/eXStatAHybridBalancedWiring.gif
   
  You would need two of those 4-position insulated term blocks.  One for each lead of the heater secondary.  Bring the lead from the heater secondary into a block, then jumper it down to hit the other three positions.  Then one lead from that term block goes to the same side of each heater term block on the amp boards.  Repeat the procedure for the other secondary heater wire and you will have complete heater circuits.
   
  EDIT:  Beefy is also correct, the grounding is not correct.  Ground from the PS goes to the main SG point at the top of your chassis.  The two SG points on the amp boards need to be brought to that star ground point too.


----------



## TimJo

Disconnect the purple twisted pairs from the central terminal block. What you want to do is connect one side of each pair to one of the green wires from the transformer, and the other side of each pair to the other green wire.
   
  Right now you have the extra little loops of green wire in the terminal block which is providing two connection points for each side of the AC heater winding, but those are not really necessary unless you can't fit all four purple wires into a single connector.
   
  Basically you want the heaters to all be connected in parallel.
   
  Yes, Beefy is correct. The grounding needs to be fixed up as well. You need to have a green ground wire on each board all going to your 'star ground' connection with the screw. Right now you have a ground wire going from the power supply to one amp board. Each ground connection on each board should go to the screw in the upper right.
   
  I hope this makes sense.


----------



## TimJo

Looks like BMF responded as well. 
	

	
	
		
		

		
			




   
  Ask us questions if you don't follow...


----------



## rbarth

The grounding error and how to fix that seems clear.  It also seems that BoilerMakerFan and TimJo are telling me essentially the same thing:  I should have two pairs of four gang interconnects with one of the secondary transformer wires connected to each interconnect and then three jumpers from it to the other three ports on that side.  Wires on the other side of each interconnect go to the heater terminal connectors.  All wires from one interconnect go to the same side of the heater terminal connectors (say, the right connector looking at the side where the wires are inserted).  The wires from the second interconnect then get inserted into the other side of the heater terminal connectors (left in my example).  Yes?


----------



## TimJo

Yes. 
   
  It could be done with fewer interconnects if you want to double up some of the purple wires, but it sounds like you understand.


----------



## BoilermakerFan

Quote: 





rbarth said:


>


 
   
  TimJo is right, you probably don't need a new term block.
   
  Using your pic I quoted.  Let's number the top heater points in the term block 1-4, L-R.
   
  Take the wires out of point 1 and separate them.  One wire goes back into point 1 and one needs to go into point 3.  The wires from 2 need to be split and go into 2 and 4.  The wires from 3 need to split and one goes to point 1 and the other goes back into 3.  The last wires are pulled from point 4 and split then individually inserted into point 2 and 4.  This will put 2-wires in each term block point, but they are split and the heaters are complete. 
   
  If that makes sense, it will get your heaters up and running. 
   
  EDIT:  One final observation, and this is just me, but I would use metal screws and nuts to mount the transformer.  Just in case it ever developed an internal short, the frame would be grounded and it will blow the fuse and not be a shock hazard.  Also, the tops of the PS caps are live, so if your arm or a tool rests across them with power, it will bite you.  I think Beefy or somebody else recommended putting electrical tape over the metal end caps to protect you while doing the testing and such.


----------



## rbarth

Simpler to me is always better.  I will stick with the four gang interconnect, rearrange the purple wires, fix the ground and get back to you all.  Thanks very much, gents!


----------



## rbarth

Appreciate your EDIT, BoilermakerFan.  Right now I have a rubber grommet that I cut in half and placed on both sides of the base of the transformer.  Screw/washer  above the top grommet half and spacer below the bottom grommet half.  Should I leave them when I reconnect transformer with metal hardware or should they go?  (I put them there to absorb vibration....)


----------



## BoilermakerFan

Quote: 





rbarth said:


> Appreciate your EDIT, BoilermakerFan.  Right now I have a rubber grommet that I cut in half and placed on both sides of the base of the transformer.  Screw/washer  above the top grommet half and spacer below the bottom grommet half.  Should I leave them when I reconnect transformer with metal hardware or should they go?  (I put them there to absorb vibration....)


 

 The grommet should be fine. since you will have metal to metal contact from the top through to the washer and nut below.  It's not required, but I like the extra protection when using a metal cased or uncased transformer.  their failure rate is low, but transformers can short out, especially if a large surge or spike came through the power line.


----------



## rbarth

Made the changes.  The tubes are working and all of the offsets are very close to 0 (0.25 to 0.65).  Now waiting for amp to stabilize.  Will take readings again in half hour.  Again, many thanks to you all!


----------



## runeight

Check your rails again too to make sure that they are still at 300V.
   
  If the rails are good and the offset/balance are good, I guess you can plug in headphones.


----------



## rbarth

Right.  As soon as I figure out how to wire the inputs. 
	

	
	
		
		

		
		
	


	




  (Working on it....)


----------



## ujamerstand

About the hybrid boards heatsinks not grounded, I do see traces connecting one side of the heatsink mounting pins that leads to the SG terminal on the hybrid boards. This means we don't have to wire the heatsinks to ground manually, right? Or are we suppose to ground the heatsinks for q13 and q14 as well?


----------



## runeight

You know, you're right. It appears that I did put them on the hybrid boards and I didn't even look at the boards before sending them out. 
	

	
	
		
		

		
		
	


	



   
  You don't need to ground the heatsinks for Q13/Q14 IIRC, Others may remember differently with their hybrid builds. I say don't make these ground connections and see if it all works.
   
  But, remember to solder the heatsink pins to the pads for the grounded heatsinks to ensure that they are grounded.
   
  How's your input wiring going?


----------



## JimP

Hi, trying to find and commission an experienced DIY builder to build a SS exstata for me.  I have procure the boards (plus some parts) second hand.  I will compensate.  Relaxed about timing, even if it takes a year.  Please let me know, or if you could guide me to someone.
   
  (mods, please remove if it's inappropriate to post something like this here)


----------



## cat6man

hi folks,
   
  after missing out on the 1st and 2nd round of the board purchases, i was fortunate enough to get
  2 responses to my request for an unneeded hybrid set of boards (i took a 2nd purchase since it also offered
  a full BOM which saves me a lot of time ordering).
   
  now i have a "hybrid" board set to pass on, at my cost (heck, i'll pay the $1.25 shipping, i'm so happy to have
  boards to build an eXStatA) to the first responder.
   
  i'll be out playing tennis so i won't be responding until tonight, but i'll go with the first request to message me.


----------



## BoilermakerFan

I think there was another member or two who wanted hybrid boards in the board GB thread...


----------



## cat6man

thanks, i'll post the offer there as well


----------



## cat6man

boards taken


----------



## rbarth

Well, gents, it’s the end of the hybrid build road for me and the beginning of a journey into a phenomenal listening experience.  (I can already tell:  I  pulled some Miles and Keith Jarrett trio CDs off the shelf and they never sounded better!)
   
  Thanks to all of you who responded to my posts and so helped me get this done.  Special thanks go to TimJo, who via a bunch of emails on Saturday, came up with the clearest and most comprehensive guide imaginable for how to wire the inputs.
     
  Photos and impressions will follow after listening for a while.  (Should I post them here or on the new builds thread?)
   
  Finally, thanks Alex very much for your generosity.   Your eXStatA is truly a gift that I will enjoy for a long, long time.


----------



## wink

Boards and tubes showed up
  Many thanks to Al and Al.


----------



## jjinh

Quote: 





wink said:


> Boards and tubes showed up
> Many thanks to Al and Al.


 

 That's good news!


----------



## pabbi1

Ok, I have heard from 5 Oz (and PacRim) folks regarding connectors -
   
  Wink - 3
  Noeb - 2
  Chinsettawong - 2
  Chaotic Angel - 2
  Rolotube - 1
   
  I am sending 15 to Rolotube, and all can ping him with how to get them from there (well, if Tony is still up for it). I was afraid there wouldn't be enough to go around, but it looks ok so far. I'll box them tonight, but will have to see when I can post (certainly in the next couple of days). Customs forms... ugh.
   
  Now we have another member, what is everyone else waiting for?


----------



## pabbi1

Quote: 





rbarth said:


> Well, gents, it’s the end of the hybrid build road for me and the beginning of a journey into a phenomenal listening experience.  (I can already tell:  I  pulled some Miles and Keith Jarrett trio CDs off the shelf and they never sounded better!)
> 
> Thanks to all of you who responded to my posts and so helped me get this done.  Special thanks go to TimJo, who via a bunch of emails on Saturday, came up with the clearest and most comprehensive guide imaginable for how to wire the inputs.
> 
> ...


 


 Congratulations - hope the revelations keep on coming.
   
  There is an impressions thread that is woefully underutilized - and I think we all owe AC feedback, good and not. There are no perfect designs, only choosing the tradeoffs most important to you.
   
http://www.head-fi.org/forum/thread/462138/first-impressions-exstata-diy-electrostatic-amp


----------



## rolotube

pabbi
   
  No worries, happy to help out with distribution of connectors down here & in the region.
   
  PM me with details at your convenience.


----------



## chinsettawong

Quote: 





pabbi1 said:


> Ok, I have heard from 5 Oz (and PacRim) folks regarding connectors -
> 
> Wink - 3
> Noeb - 2
> ...


 

 Thank you, Al.  I'm looking forward to receiving them soon.  I'll ping Rolotube.  
   
  As for the build, I'm still waiting for some transistors.  I'm having a difficult time finding the high voltage PNP tr around here.
   
  Wachara C.


----------



## ujamerstand

The tubes from Al has safely arrived. Thanks! I would love to trade one of my RCA disc-getter tube with somebody else's RCA d-getter tube though, I just need one more and I will get 4 d-getter tubes!


----------



## paxeaxe23

Quote: 





rbarth said:


> ...Special thanks go to TimJo, who via a bunch of emails on Saturday, came up with the clearest and most comprehensive guide imaginable for how to wire the inputs.
> 
> Photos and impressions will follow after listening for a while.  (Should I post them here or on the new builds thread?)...


 
  Might be useful [assuming TimJo doesn't mind] if you posted some of that Clear and comprehensive guidance here in this forum for reference.
   
  There is a first impressions thread in existence  started by Pabbi1 if I remember correctly


----------



## ujamerstand

Quote: 





ujamerstand said:


> I would love to trade one of my RCA disc-getter tube with somebody else's RCA d-getter tube though, I just need one more and I will get 4 d-getter tubes!


 

 Anybody? 
   
  Anyways, the most important component for this project has arrived. 
   

   
  brings a little tear to my eyes...


----------



## jjinh

Quote: 





pabbi1 said:


> Ok, I have heard from 5 Oz (and PacRim) folks regarding connectors -
> 
> Wink - 3
> Noeb - 2
> ...


 
   
  If it's not too late I'd also like some stax connectors. Just stick a few more in Wink's package and they'll get to me. Thanks!


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> Anybody?


 

 Pabbi is probably the only one who could help you out...


----------



## ujamerstand

I remember all of them has been sent out... I'm hoping that at least one other person who got the RCAs from pabbi would have a D-getter tube that they are willing to trade.


----------



## runeight

Gentlemen, in the last week several of you have emailed me about failure conditions if one tube goes out in the hybrid. Most of you were concerned about the PS.
   
  In this situation, there isn't any risk to the PS because the current demand from the tubeless channel is not much lower than a working channel and the additional heat in the PS will not be severe nor damage it.
   
  However, these questions forced me to look at the hybrid amp again just to explore this failure condition more.
   
  Most of you would probably power down quickly if one side of the amp went out, but if the amp is left on with one (or both) tubes not lit then resistors R31 to R34 will exceed their power dissipation. If you want to be safe against losing these resistors, if you don't turn the amp off right away or it is left unattended, the easy fix is to use 1/2W resistors instead of 1/8W.
   
  You can use 71-CCF55-75K or 273-75K-RC. They are longer than the RN55D but they should still fit if you tilt them at an angle.
   
  There are quite a few hybrids out there in service and no one has reported this problem yet, but it will surface when tubes start to die during operation.
   
  I'd like to have caught this a while ago gents, but just didn't see this corner case.
   
  Thanks to everyone who asked the question.


----------



## les_garten

Quote: 





runeight said:


> Gentlemen, in the last week several of you have emailed me about failure conditions if one tube goes out in the hybrid. Most of you were concerned about the PS.
> 
> In this situation, there isn't any risk to the PS because the current demand from the tubeless channel is not much lower than a working channel and the additional heat in the PS will not be severe nor damage it.
> 
> ...


 


 Hi Alex,
     Any possibility of changing this in the BOM online?


----------



## pabbi1

Well, I am completely out of anything other than (NFS) Tung Sol, so I'm no help there. You might ping one of the eBay sellers, though shipping for a single tube is always excessive. You might also ping one of the internet sellers (http://www.vacuumtubes.net/ comes to mind, or www.Tubedepot.com ), This looks like a good candidate. 
   
  Pity I am chasing different glass at the moment, so doubtful I buy any more 6s4a tubes.
   
  On a far happier topic, a box with 15 Stax connectors left Dallas today heading for Oz. I *think* 13 are spoken for, with Jin getting 2 (or 3), so:
   
  Wink - 3
  Noeb - 2
  Chinsettawong - 2
  Chaotic Angel - 2
  Rolotube - 2
  Jinh - 2 (unless you are doing two builds, then 3)
   
  So, there are one or two left unclaimed, and I will leave it solely at Tony's discretion as to how they get distributed, SO, everyone ping Rolotube to arrange postage out to you, as he should see the box this time next week.
   
  Should be some building frenzy about now, eh?


----------



## jjinh

I suppose it's 2 then. Thanks!


----------



## runeight

Quote: 





les_garten said:


> Hi Alex,
> Any possibility of changing this in the BOM online?


 


 Yes. I'll try to get to it tonight or tomorrow night along with adding something on the website to draw attention to it.


----------



## runeight

BoM is changed on the website.


----------



## les_garten

Quote: 





runeight said:


> BoM is changed on the website.


 


 Thanx Alex, Top notch as usual!


----------



## ujamerstand

One less check before mouser order reveals MJE340STUs are out of order. would 863-MJE340G be an adequate substitute? its VEBO rating is 3V rather than 5V.
   
  Nevermind. Answered my own question.


----------



## rbarth

Quote: 





runeight said:


> Gentlemen, in the last week several of you have emailed me about failure conditions if one tube goes out in the hybrid.


 

 How long are these tubes supposed to last?  Or is there too much variability to answer that question meaningfully?


----------



## runeight

Depending on the operating conditions, tubes last in the range of thousands of hours. Power tubes have a shorter life, preamp tubes, on average, can last longer.
   
  Generally, tubes rarely die because the filament dies and stops heating the cathode. Good manufacturing tries to ensure that the filament will outlast the ability of the cathode coating to emit electrons. So, the failure mode that we're accounting for here is pretty unlikely, but possible.
   
  The most common way that tubes die is that their current emissivity slowly drops. This alters the operating point conditions and, usually, the amp just starts to sound bad.
   
  The other common way is that they get gassy and the getter simply can't keep up with the gas. You'll see this when the silver getter starts to turn white.
   
  Another way that tubes are damaged is by applying high voltage before the heaters are warmed up. In the good old days this was handled by using tube rectifiers which caused the HV to come up slowly because the recitifier was also heating up along with the rest of the tubes.
   
  With modern sand rectifiers the HV comes up almost immediately and applies voltage before the tubes are conducting. The common solution, as you all know, is to first turn on the heaters and then turn on the HV. Although we haven't discussed this much on the thread, it wouldn't hurt to power up the hybrid this way. We haven't made a big deal over it in order to keep things simple.


----------



## paxeaxe23

Anyone know a source for 6S4A Tubes in Germany (or anywhere in Europe)  I have only found one source and I do have a set of 4 tubes, but he charges a whopping 14 Euros each. I regularly see these tubes on eBay in the US for 3 - 4 Dollars and it looks like Pabbi1 has had fun stock piling them (well some of those photos do look great, almost as exciting as a pile of gold bars!) 
   
  Still, I haven't come across a ready supply here in Europe at reasonable prices, and it is probably a good idea to get hold of at least one more set (and a matched one too, mine isn't) .  Any suggestions?


----------



## rolotube

Quote: 





pabbi1 said:


> Well, I am completely out of anything other than (NFS) Tung Sol, so I'm no help there. You might ping one of the eBay sellers, though shipping for a single tube is always excessive. You might also ping one of the internet sellers (http://www.vacuumtubes.net/ comes to mind, or www.Tubedepot.com ), This looks like a good candidate.
> 
> Pity I am chasing different glass at the moment, so doubtful I buy any more 6s4a tubes.
> 
> ...


 
   
  Thanks pabbi.  They will go to good homes.


----------



## BoilermakerFan

Quote: 





paxeaxe23 said:


> Anyone know a source for 6S4A Tubes in Germany (or anywhere in Europe)  I have only found one source and I do have a set of 4 tubes, but he charges a whopping 14 Euros each. I regularly see these tubes on eBay in the US for 3 - 4 Dollars and it looks like Pabbi1 has had fun stock piling them (well some of those photos do look great, almost as exciting as a pile of gold bars!)
> 
> Still, I haven't come across a ready supply here in Europe at reasonable prices, and it is probably a good idea to get hold of at least one more set (and a matched one too, mine isn't) .  Any suggestions?


 
  I'm checking with a secret source in Europe.   Dropped him and email and sent you a PM.


----------



## pabbi1

Yes, PM also sent - for a known honey hole - good luck!
   
  Oh, and I bought a Koss ESP-950 today (impulse buy off CL)... just a pity it has to be reterminated, so I can now see if there is the same synergy as he60 and 404LE... at the proper bias


----------



## BoilermakerFan

Quote: 





pabbi1 said:


> Yes, PM also sent - for a known honey hole - good luck!
> 
> Oh, and I bought a Koss ESP-950 today (impulse buy off CL)... just a pity it has to be reterminated, so I can now see if there is the same synergy as he60 and 404LE... at the proper bias


 
  Al, do you just want a whole new Stax cable?  I have one for ya'.   
  
  I don't think it will quite as nice as the HE60s, especially if the custom HE60s really improve over the stockers, but I bet it will sound pretty sweet and a few mods to the 950s later can raise it up a notch too.


----------



## sachu

I think I am now very very interested to do a direct comparison with an O2MK1 + Exstata versus a nice LCD-2 system. Had a chance to listen to an exstata i built for a friend months ago with the O2Mk1 today and I was blown away. While the Wharfie zebs edge out the O2 in some very specific areas the stat system around the O2 annhilates the wharfie zebrawoods + Liquid gold setup. The effect is similar to the LCD-2 for me. 
   
  Wish I could spend some serious time with an O2 + Exstata system. Sadly the O2 wasn't mine, nor is the exstata. But you guys who managed to grab boards are a lucky lot. Lots of enjoyment to fill these forums shortly i suspect.


----------



## HeadphoneAddict

Quote: 





sachu said:


> I think I am now very very interested to do a direct comparison with an O2MK1 + Exstata versus a nice LCD-2 system. Had a chance to listen to an exstata i built for a friend months ago with the O2Mk1 today and I was blown away. While the Wharfie zebs edge out the O2 in some very specific areas the stat system around the O2 annhilates the wharfie zebrawoods + Liquid gold setup. The effect is similar to the LCD-2 for me.
> 
> Wish I could spend some serious time with an O2 + Exstata system. Sadly the O2 wasn't mine, nor is the exstata. But you guys who managed to grab boards are a lucky lot. Lots of enjoyment to fill these forums shortly i suspect.


 

 If you really think you would use an eXStatA for yourself, I have a set of Hybrid boards that I could pass on to you so you could build your own amp.  This offer is for you only, so I don't want PM from other people about them right now. I did offer them to Paxeaxe but he found another set.  Otherwise I planned to build a hybrid amp for myself someday, since I'm giving the completed hybrid to my son.


----------



## BoilermakerFan

I also have two SS boards sets, matched quads of the J271s, and PS iron kits still available.  Posting here, then they'll posted in the FS forum next week.


----------



## HeadphoneAddict

Quote: 





headphoneaddict said:


> If you really think you would use an eXStatA for yourself, I have a set of Hybrid boards that I could pass on to you so you could build your own amp.  This offer is for you only, so I don't want PM from other people about them right now. I did offer them to Paxeaxe but he found another set.  Otherwise I planned to build a hybrid amp for myself someday, since I'm giving the completed hybrid to my son.


 
  Quote: 





boilermakerfan said:


> I also have two SS boards sets, matched quads of the J271s, and PS iron kits still available.  Posting here, then they'll posted in the FS forum next week.


 

 It looks like Sachu wants to take my hybrid set.  If he does, I would like to buy one of your "SS set with J271's and PS iron kits".  I'll know by this afternoon.


----------



## BoilermakerFan

Quote: 





headphoneaddict said:


> It looks like Sachu wants to take my hybrid set.  If he does, I would like to buy one of your "SS set with J271's and PS iron kits".  I'll know by this afternoon.


 

 Works for me Larry.  Saachi emailed me, but we can take it to PMs as you have two options on the iron I need to help you with.  I'll pass the boards on to you at the GB cost and the iron at cost too.  Marc just mailed the J271s so they'll be here early next week.


----------



## ujamerstand

For those of you who worked on par metal cases, does par metal provide 6mm thick panels? Also, for those of you who made CAD drawings of the panels, how did you find out the locations for the mounting screws? Anyone has a measurement?


----------



## sachu

measurements for the mouting screws was just that measurement. A tip, if you are planning on an FPE panel for a par metal chassis (looks very very good btw) i'd suggest buying the par-metal chassis sans the front and rear panel, just get the chassis with the mounting brackets for both front and back. It is cheaper that way.


----------



## ujamerstand

So buy the chassis and measure? not sure if I'd have an accurate measurement.... The only thing I don't like about FPE is that the edges of their panels are not anodized. But then again, I do save the efforts of shipping the panels to them.
   
  I remember another place that does front panels, but cannot recall its name right now. Starts with a c or something...


----------



## sachu

Camexpert.
   
  Well if it is the 20-12124 case you are looking at, then let me know and i'll forward you the mounting hole measurements for it.
   
  edit: a quick shout out to rbarth for the set of quad Jfets he sent me for the last SS exstata build that has been languishing for close to 8 months now. most appreciated. I will hopefully get to test the boards out today.


----------



## MashBill

sachu,
  Please send me the mounting hole measurements.
   
  I didn't know that the cases could be ordered sans front and rear panel.
   
  Thanks for sharing the info!
   
  Bill


----------



## jlefley

I recently bought an enclosure from Par-Metal for use with panels I had Cam-Expert machine.  Cam-Expert was cheaper than the same panel designed in FPE.  As stated, you can order the Par-Metal enclosure without a front panel and with an additional frame instead of the standard back if you want a custom machined rear panel as well.  The mounting hole dimensions should be pretty easy to measure once you have the frames in front of you.  I used a 20-12123 (12" x 12" x 3") and the holes were 11.2" x 2" apart, centered on the frame.  I would imagine the 11.2" dimension would be constant for all 12" wide cases and maybe you just subtract 0.8" from the case width to get the dimension for any case width?  and maybe take an inch off the height to get the vertical dimension for any case height.  This is just a guess but it might be something to think about when you take a pair of calipers or a ruler to your case frames.  Also FWIW, I sized my panels at 12.25" x 3.25".  This left an 1/8" overhang over the front profile of the enclosure which looks good when the panel is installed.  (These cases/panels were for a different amp; the actual case and panel dimensions probably wouldn't work for an eXStatA but the 1/8" overhang would probably be appropriate for a variety of case sizes) 
   
  If you are thinking about getting a panel made from the pre-anodized aluminum that Cam-Expert and FPE uses, the edges will be raw aluminum.  Its not really an issue if you are using a silver case with a clear anodized panel but if you want black then it might be of concern.  I wanted the edges on my black panels to be anodized which meant that they had to be anodized after milling.  I contacted FPE and they do not offer this service.  Cam-Expert quoted me $150 total for 4 panels.  I checked with some local anodizing companies and ended up getting the panels machined be Cam-Expert from raw aluminum and then had them anodized locally for $60 for all 4.  This is another option to consider if you want the edges to be finished.


----------



## ujamerstand

Right, that's another thing I like about Cam-expert, they could mill your panels, then anodize your panels afterwards. I didn't see the price on the website though. $150 seems a little high for just a little more visual effect on the over all finish. How much did FPE's quotes (on milling) differs from Cam-expert?


----------



## sachu

[size=medium]As i won't really be building any more amps in the foreseeable future, i'd like to submit my FPE files for anyone to use as they wish. Please donot use the Cavalli Audio logo without express permission from Alex Cavalli.
   
   
  here are links to download the fpe files. You can use them as templates. Will save you a ton of work.
   
http://web.pdx.edu/~savyak/exstata/
   ​[/size]


----------



## ujamerstand

This is most useful. Thank you very much!


----------



## BoilermakerFan

Quote: 





sachu said:


> As i won't really be building any more amps in the foreseeable future, i'd like to submit my FPE files for anyone to use as they wish. Please donot use the Cavalli Audio logo without express permission from Alex Cavalli.
> 
> 
> here are links to download the fpe files. You can use them as templates. Will save you a ton of work.
> ...


 

 The CA label should really be removed from the front panel since Cavalli Audio is now MOT.


----------



## sachu

Updated front panel template for use with WPI jacks. The earlier one was for the ones made by luvdunhill. Am guessing more folk are using the WPI/Amphenol ones.


----------



## jlefley

Quote: 





ujamerstand said:


> Right, that's another thing I like about Cam-expert, they could mill your panels, then anodize your panels afterwards. I didn't see the price on the website though. $150 seems a little high for just a little more visual effect on the over all finish. How much did FPE's quotes (on milling) differs from Cam-expert?


 

 They don't list the price on the website.  I asked about it when I was getting a quote on my panels and that what it was.  I went through a local company and it was less than half of Cam-Experts price.  I had my panels made from 6mm material and Cam-experts price was about the same as FPE's price for 4mm as quoted by their software.  I never got a quote from FPE for 6mm panels but it would have obviously been more than the 4mm price.


----------



## HeadphoneAddict

Quote: 





sachu said:


> [size=medium]As i won't really be building any more amps in the foreseeable future, i'd like to submit my FPE files for anyone to use as they wish. Please donot use the Cavalli Audio logo without express permission from Alex Cavalli.
> 
> 
> here are links to download the fpe files. You can use them as templates. Will save you a ton of work.
> ...


 

 Just curious, since I can't open these - are these the same design that I had you develop for my eXStatA?


----------



## sachu

well the design that I developed for someone else prior to you was changed and modified as per your requests. The front panel template i had earlier was the one used in your design.
   
  But i took that down and put up the original front panel design that I modified to suit your needs without the CA logo as it was made for the WPI jacks and figured that would be more handy to folks here..
   
  The rear panel template is the one used in your amp but is now being replaced with a more general template as yours was quite specific.


----------



## HeadphoneAddict

Quote: 





sachu said:


> well the design that I developed for someone else prior to you was changed and modified as per your requests. The front panel template i had earlier was the one used in your design.
> 
> But i took that down and put up the original front panel design that I modified to suit your needs without the CA logo as it was made for the WPI jacks and figured that would be more handy to folks here..
> 
> The rear panel template is the one used in your amp but is now being replaced with a more general template as yours was quite specific.


 

 That makes more sense.  You anticipated my concerns exactly.


----------



## sachu

Aye Larry.
   
  Wish I could post pics of the amp here as this is one sweet looking amp if I may say so and am rather jealous of you now lol.
   
  I wrote off the exstata after listening to the proto version with the ESP950 and O2.. but once i heard the final version it became clear to me what a big step up the addition of the output CCS made to the amp.
   
  For now am loving the SR-003 with this amp, damn impressive for the baby stax.  
  wish the colorado meet was after the portland meet so the guys in PDX could listen to it.


----------



## BoilermakerFan

Whose 003s are they?


----------



## sachu

Larry's
   
  Right now grooving to the Liquid Fire and the Liquid Gold here at 32 Ohm Audio. Ken's taken both his LCD-2s and Immitbiker has Kevin's LCD-2..so bummed, have to settle for some T1 something headphones


----------



## BoilermakerFan

Quote: 





boilermakerfan said:


> I also have two SS boards sets, matched quads of the J271s, and PS iron kits still available.  Posting here, then they'll posted in the FS forum next week.


 

 Both sets of SS boards and iron are sold.


----------



## ujamerstand

Got the 6-pin sockets from allied electronics today. All I gotta say is wow, what crappy construction.
   
  Anyways, for the bias wiring, what would be an appropriate AWG? One bias wire carries ~580V and the other ~230V, but neither have current load on them, is this correct? Does this mean that we don't have to care too much about the gauge of the wire except for its voltage rating?


----------



## TimJo

Quote: 





ujamerstand said:


> Got the 6-pin sockets from allied electronics today. All I gotta say is wow, what crappy construction.
> 
> Anyways, for the bias wiring, what would be an appropriate AWG? One bias wire carries ~580V and the other ~230V, but neither have current load on them, is this correct? Does this mean that we don't have to care too much about the gauge of the wire except for its voltage rating?


 

 That's my understanding. I used 22 ga rated for 600 volts, but you could probably use 24 ga as well.


----------



## ujamerstand

^^Excellent, thank you.


----------



## spritzer

You can use 30AWG or even smaller but the voltage rating is the main point here and that the wire isn't fragile enough to break.


----------



## pabbi1

I usually use Mil 16878/5 in 22awg, but 600v rated is fine. I just use what I happen to have.
   
  So, one build is finished out of 50 board sets?


----------



## ujamerstand

Another one is on the way. Got my mouser package today.
   

   
  Everything else should slowly arrive within the next 3 weeks or so... I'm going through the package right now to see if I missed anything. Unfortunately, the C6 I got was too wide. I didn't like the plastic xlr inputs I bought either. So another mouser run for me.


----------



## sachu

^^ That logo is wicked nice!!


----------



## HeadphoneAddict

Here are a couple of photos of my solid state eXStatA that Sachu cased up for me.  I should have it here in a couple of days.  It has a digital attenuator and teflon stax jacks from luvdunhill, and FPE 6mm front panel to allow mounting the jacks from behind.  Alex sold his spare stuffed SS boards to Blutarsky who passed them on to me, and Alex gave permission to use his logo in this DIY amplifier.


----------



## krmathis

ujamerstand said:


> Another one is on the way. Got my mouser package today.


 

 Really clean looking logo. An official one, or something of your own design?


----------



## ujamerstand

Quote: 





sachu said:


> ^^ That logo is wicked nice!!


 
  Quote: 





krmathis said:


> Really clean looking logo. An official one, or something of your own design?


 

 Thanks guys, I designed that logo. But I must thank n_maher and his exstata build for the inspiration. That build kicks ass!


----------



## ujamerstand

Well... I've been looking for replacements for C6. I could not find a suitable 100nF 1000v film cap with 22.5mm lead spacing at mouser, and the one in stock at digikey is slightly too wide. Newark is out of stock for the cap value, and farnell lists them as expecting shipment but does not list the date. The only place that has possible replacement right now is an ebay seller in Hong kong (http://cgi.ebay.com/WIMA-MKP10-Polyproplyene-Capactor-0-1uF-1000V-
	

	
	
		
		

		
		
	


	




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" width="" />-PCS-/320573786201),which is probably going to take forever to arrive. What are my options here? Anyone have a spare cap lying around?
   
  Worst comes to worst I can always wire the one I've got (which is too long) off board I guess...


----------



## Beefy

Perhaps try these guys: http://www.ttiinc.com/page/home
   
  I'm pretty sure that there was a group buy for Wima caps from them way back during the first beta run.


----------



## ujamerstand

They don't have the 22.5mm lead spacing version in stock right now.


----------



## pabbi1

Vishay - BFC246860104  (Arrow North America)
   
http://www.arrownac.com/
   
  May be a bit thick, but perhaps Runeight could provide a waiver?
   
  I use a lot of Panasonics (kinda like these), which require just a bit of bend to fit well - worth a shot, and a bit closer to home.
   
  Oh, and I do love the logo. Pure win.


----------



## ujamerstand

BFC246860104 is just slightly larger, I think it would obstruct d5 and d6 unless I bottom mount those. Those panasonics looks good though, I'm grabbing a set just in case. I'm going to guess that the polyproplyene cap is there to provide that a little bit more performance over polyester cap? 
   
  btw, nice DP


----------



## BoilermakerFan

Quote: 





pabbi1 said:


> Vishay - BFC246860104  (Arrow North America)
> 
> http://www.arrownac.com/
> 
> ...


 

 I love the new custom title!  I need Nate to give me a Cavalli Audio title too.


----------



## TimJo

Actually it was these folks. Give them a call. They were very helpful in supplying us the WIMA caps on the original group buy. 
   
  http://www.tawelectronics.com/wima_film_capacitors.htm
  
  Quote: 





beefy said:


> Perhaps try these guys: http://www.ttiinc.com/page/home
> 
> I'm pretty sure that there was a group buy for Wima caps from them way back during the first beta run.


----------



## ujamerstand

I tried ordering online using their shop before, but I couldn't get access to the cart for some reason...


----------



## sachu

Only postingto give you an idea of what's under the hood of HeadphoneAddict's eXStata. Not the neatest,but it a lot of wires in the rear of the amp.
  There's a Placcid PSU for the volume control board.
  Teflon jacks (very sweet btw), and Volume control board and control software by Luvdunhill.
   
  Boards were stuffed and tested by Alex Cavalli.


----------



## HeadphoneAddict

Quote: 





sachu said:


> Only postingto give you an idea of what's under the hood of HeadphoneAddict's eXStata. Not the neatest,but it a lot of wires in the rear of the amp.
> There's a Placcid PSU for the volume control board.
> Teflon jacks (very sweet btw), and Volume control board and control software by Luvdunhill.
> 
> Boards were stuffed and tested by Alex Cavalli.


 

 I had popped the hood and took photos tonight, but you beat me to it.  I'm packing up for the Colorado meet, but will hook this up in the AM to my CDP-8 on the kitchen table and give it a listen.  Thanks!
   
  In comparison, here is my Hybrid amp:


----------



## Beefy

Quote: 





timjo said:


> Actually it was these folks. Give them a call. They were very helpful in supplying us the WIMA caps on the original group buy.
> 
> http://www.tawelectronics.com/wima_film_capacitors.htm


 


 I knew it was T-something, and TTI came up first on a Google search. Thanks for clearing it up!


----------



## marcus1

Hi all
   
  Finally got my act together and started building the tubed eXStata a couple of days ago.  I've finished the power supply and decided to test it before going on to assemble the amp boards.  All looks well with the following readings:
   
  Line AC: 237V
  Secondary AC: 252V
  T1 to gnd: 328V
  T3 to gnd: 327V
  Rail voltage: approx 299V -/+
   
  Most of the components are mounted on the amp boards and I'm now testing the Jfets.  Out of the 20 I bought I got the following groups >10mA:
   
  10.9
  11.0
  11.2
  14.3
   
  and:
   
  18.8
  19.7
  19.8
  20.9
   
  I guess the 2nd group is my best bet but the quad range is above the recommended 10% at around 11%.  Is this OK to use these (I hope!) and if so would I combine the 18.8 with the 19.7 and the 19.8 with the 20.9?
   
   
  Tim (marcus1)


----------



## wink

marcus1,
  You did well,
  I got 40 of 'em and got 1 set of 4 within 10% and 3 lots of 3 within 10 percent.
   
  13 out of 40 above 10mA  - not so good
  Half of them were 7mA and lower.
  None were over 17.5mA.


----------



## marcus1

Just trying to make sure I understand the 10% range recommended for the J271 jfets. 
  As far as matching the jfets within the 10% parameter goes, does this mean that (for example) Q1L/Q1R must be within 10% of each other or that the four jfets together must be within the 10% range?
   
  cheers
   
  Tim
   

  
  Quote: 





marcus1 said:


> Hi all
> 
> Finally got my act together and started building the tubed eXStata a couple of days ago.  I've finished the power supply and decided to test it before going on to assemble the amp boards.  All looks well with the following readings:
> 
> ...


----------



## ujamerstand

In this case, all four jfets should be matched within 10% to minimize channel imbalance.


----------



## marcus1

OK, thanks ujamerstand. I've ordered some more jfets to try and get a closer grouping.
  Quote: 





ujamerstand said:


> In this case, all four jfets should be matched within 10% to minimize channel imbalance.


----------



## rolotube

Quote: 





pabbi1 said:


> Ok, I have heard from 5 Oz (and PacRim) folks regarding connectors -
> 
> Wink - 3
> Noeb - 2
> ...


 
  Connectors have arrived.  Many thanks to pabbi for providing these hard to get parts.  I will be sending on to those who have pinged me in the next day or so.
   
  Eleven have been accounted for so there are four remaining for Oz & PacRim builders.


----------



## jjinh

Quote: 





> Originally Posted by *rolotube* /img/forum/go_quote.gif
> 
> Connectors have arrived.  Many thanks to pabbi for providing these hard to get parts.  I will be sending on to those who have pinged me in the next day or so.
> 
> Eleven have been accounted for so there are four remaining for Oz & PacRim builders.


 
   
  I should also be on that list you quoted... send me a couple of connectors (i.e. two) in wink's package. Thanks!


----------



## ujamerstand

Today I've built the attenuator circuit for this build. Its a dantimax relvol3 balanced relay attenuator. It works beautifully. I also like the way it clicks as I turn the knob.  There's even a built in IR receiver, which I'll need to grab a remote for from fleabay. 
   
  Here is a bunch of things in there for comparison. I'll need to slap a heatsink on that regulator, its getting hot.


----------



## luvdunhill

I have a bag full of JFETs that have been selected to be greater than 11mA Idss measured at 12v. Is there need for more matched JFETs? I could either sell the lot to a single person that would then match them up, or I could do the matching myself I guess.


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> Today I've built the attenuator circuit for this build. Its a dantimax relvol3 balanced relay attenuator. It works beautifully. I also like the way it clicks as I turn the knob.  There's even a built in IR receiver, which I'll need to grab a remote for from fleabay.
> 
> Here is a bunch of things in there for comparison. I'll need to slap a heatsink on that regulator, its getting hot.


 

 Ah cool.  Let us know how it sounds.  I might go for a kit too simply because the iR receiver would be super helpful in my new home office/listening area arrangement.  I didn't even know that kit was out.  Did you get a 25K, 50K, or 100K kit?


----------



## ujamerstand

I bought the 10k resistor kit. No high Zo tube sources for me. A short listening session told me that it was functional.  Otherwise I'll have to setup up a simple amp/buffer stage to test whether I could tell a difference between the kit and a rk27.


----------



## bidoux

Hello,
   
  I'm currently building a eXStata solid state with two VPS230-110 from Triad Magnetic. I would like to start building a case but I need to know first what dimensions would be appropriate (I don't have finished the build yet).
   
  So what dimensions should I go for ? I'm not using a fancy volume control, only a ALPS blue.
   
  thanks


----------



## pabbi1

The cases in my sig are approximately 11" square (inside, net), and it will also fit in a Sun 911 external SCSI case. Note I have the huge Acoustic Dimensions stepper, which is 2" square, so you could probably get by with 9"x 11", where it will be tight.


----------



## BoilermakerFan

Quote: 





bidoux said:


> Hello,
> 
> I'm currently building a eXStata solid state with two VPS230-110 from Triad Magnetic. I would like to start building a case but I need to know first what dimensions would be appropriate (I don't have finished the build yet).
> 
> ...


 
  Bigger is generally better.  The more space you can put between the AC and the signal wiring the less likely you will have noise issues.  More space means cooler operation too, but a highly vented small case is better than a non-vented large case. 
   
  A 75mm height would be the minimum height with 100mm being better for cooling.  I stuffed an eXStatA in a 31cm x 18cm area case that was 17cm high with 5cm space under the sub chassis to leave me room to hang an R-core transformer underneath, but I might have been able to get a 75mm^3 sized transformer on top too, but wiring was at risk of being compromised with wall AC or HV AC near signal wires.


----------



## bidoux

Pabbi1, your cases (http://home.swbell.net/pabbi/eXtube.jpg and http://home.swbell.net/pabbi/xstat.jpg) look like there is enough space in it. So I would go for a square box, 28cm long and, as Boilermarkerfan suggested, 10cm high.
   
  I think it will be enough for the interferences with the AC line. Furthermore someone said that with the extremely low sensivity of the stax earphones, noise-sensibility is not as a problem as with IEM
   
  I'm going to try to build a wood box, inspired by rbarth's and macm75's work. It will be of course much more modest, I'm not good with casework.


----------



## pabbi1

Boy, I wish I could do dovetails like rbarth... so much so that I am takig a class tomorrow at the local Rockler... hopefully without spending $$$ to make it happen. He uses a Leigh jig (good stuff), and I have a Delta. Maybe I'll settle for box joints, as I'm torn for whether to use purpleheart, marblewood or cocobolo, all just waiting in the shop.
   
  Oh, this is for a new proto build... update in a few weeks.
   
  So, like, OY! Where are all the other eXStatA builds?


----------



## HeadphoneAddict

My SS eXStatA that we had at the Colorado meet last weekend + Nuforce CDP-8 as source, and SR-003 + SR-Lambda normal bias:


----------



## les_garten

HPA,  Sweet Lookin' STAX  setup


----------



## gilency

I also need a Stax connector (or 2): if anybody has a spare one to sell please pm me. Pabbi?
  Thanks.


----------



## bidoux

Gilency, Frank Cooter sent me 5 stax connectors. They are the allied plastic ones. I can send you one or two if you want.
  PM your adress and I will do it (but I'm not sure when).
   
  Quote: 





			
				pabbi1 said:
			
		

> Boy, I wish I could do dovetails like rbarth... so much so that I am takig a class tomorrow at the local Rockler... hopefully without spending $$$ to make it happen. He uses a Leigh jig (good stuff), and I have a Delta. Maybe I'll settle for box joints, as I'm torn for whether to use purpleheart, marblewood or cocobolo, all just waiting in the shop.


 
  That is what I was thinking : really serious skills and good machines, as his work was amazing. Really good photographer too. I'm not going with exotic wood like you do, too fancy for me. Much more something like pine should do it, cheap and easy to work on.


----------



## FrankCooter

If anyone still needs 5 pin output connectors, then pm me. They are free to exSTatA builders. They are however, the Amphenols. I'll also replenish pabbi1's supply if there's the need.


----------



## BoilermakerFan

Quote: 





pabbi1 said:


> Boy, I wish I could do dovetails like rbarth... so much so that I am takig a class tomorrow at the local Rockler... hopefully without spending $$$ to make it happen. He uses a Leigh jig (good stuff), and I have a Delta. Maybe I'll settle for box joints, as I'm torn for whether to use purpleheart, marblewood or cocobolo, all just waiting in the shop.
> 
> Oh, this is for a new proto build... update in a few weeks.
> 
> So, like, OY! Where are all the other eXStatA builds?


 
  Call me old fashioned or an old Japanese woodworker soul, but I like cutting dovetails by hand with a Japanese pull saw, chisels, and great dovetail knives.  Of course, my saws, knives, dovetail guide, and chisels probably cost as much as a lower end router jig, but I like the slow process.  My first few were not tight, but they fit!  Getting better at them and I'll eventually have some worthy of pics.


----------



## ujamerstand

Quote: 





> Originally Posted by *pabbi1* /img/forum/go_quote.gif
> 
> So, like, OY! Where are all the other eXStatA builds?


 

 On vacation. 
	

	
	
		
		

		
		
	


	




 But I could benefit from some opinion on some panel designs.
   


   
  First design or second design? Of course, the dimensions of the holes are temporary right now, I still need to measure them once I get back from vacation. I need to fix up the hpgl of the logo as well, its not filling in completely right now. Also, I would like to mount the IR sensor in a way that is not obtrusive, any opinion on how I should go about to achieve that?


----------



## pabbi1

Nice designs... I'd go for the former, mainly because I'm a sucker for that font, though might get AC's input.


----------



## pidesd

the first deisgn is pretty nice, but the pro and low jacks are too close to the ''exstata'' IMO


----------



## cat6man

finally got some free time and spent a couple of hours soldering passive components today.
   
  still need to do some transistor matching though...........and decide on a box


----------



## wink

Stax connectors arrived safely.
  Many thanks to FrankCooter, Pabbi1, Rolotube.


----------



## FrankCooter




----------



## cat6man

Making some good progress now stuffing the boards, with a couple of questions embedded below (questions are #3,4,6):
   
  Hybrid board to be done:
  1) need to match q1/q2 to get quad
  2) need to assemble q11-14 heat sinks
  3) need to sfuff q3/q4 [orientation question:  i see one dot on the silkscreen, does that align with the 1 dot side of the device? - other side has 3 dots]
  4) need to stuff z1r/l [orientation question:  for tombstoned devices, i see circle with bar on silkscreen - i assume that is cathode?, i.e. end of device with bar/line]
   
  Power supply board to be done:
  5) need to assemble q3/4 and q5-8 heat sinks
  6) need to  stuff z3-14 [same orientation question as #4 for tombstoned device]
   
  Also, I ordered replacements for r31-34 to get 1/2W resistors, but order shows 1/4W and Mouser web site
  says 1/4W RATED at 1/2W.  I assume those are fine, but what does this dual 1/4 and 1/2 W rating mean
  and how does it differ from a 1/2W resistor?
   
  Thanks


----------



## FrankCooter

Somehow the text didn't go through with the photo. This is my first attempt to post a picture on this forum. Definitely still in the learning process. Anyway, the above photo is my solid state eXStatA in a repurposed case originally intended for a small DHT amp. I left the '20's era meter on because the front panel looked naked without it. Actually, I kind of like it as it adds a touch of whimsy. Thanks again Alex and Al! Great DIY project and great "bang for the buck"!


----------



## TimJo

Wow, that is a sharp looking build Frank!
   
  I love the look of the meter as well...


----------



## Beefy

Quote: 





frankcooter said:


> Anyway, the above photo is my solid state eXStatA in a repurposed case originally intended for a small DHT amp. I left the '20's era meter on because the front panel looked naked without it. Actually, I kind of like it as it adds a touch of whimsy. Thanks again Alex and Al! Great DIY project and great "bang for the buck"!


 


 That is freaking awesome Frank. Absolutely love it!


----------



## pidesd

hey guys. got a question:
   
  i d like to have a single custom heatsink per hybrid board in my build for q11,12,13,14. i know q11,12 have to be grounded. do you think it ll be ok if i just ground this heatsink?


----------



## cat6man

Quote: 





frankcooter said:


> Somehow the text didn't go through with the photo. This is my first attempt to post a picture on this forum. Definitely still in the learning process. Anyway, the above photo is my solid state eXStatA in a repurposed case originally intended for a small DHT amp. I left the '20's era meter on because the front panel looked naked without it. Actually, I kind of like it as it adds a touch of whimsy. Thanks again Alex and Al! Great DIY project and great "bang for the buck"!


 

 beyond awesome frank!  i love it.  i wonder if there would be sufficient ventilation for a tube/hybrid version?
  can you share anything about dimensions, design plans, etc?


----------



## pabbi1

Frank, what is that wood - solid or veneer? Just wild - is the bottom self cotnained, and just slides into the top cover?
   
  Just depresses me again about my casing skills.


----------



## les_garten

Quote: 





pabbi1 said:


> Frank, what is that wood - solid or veneer? Just wild - is the bottom self cotnained, and just slides into the top cover?
> 
> Just depresses me again about my casing skills.


 


 I think that depresses most of us about our casing skills.
   
  The SUN drive box ain't bad though!


----------



## cat6man

Quote: 





cat6man said:


> Making some good progress now stuffing the boards, with a couple of questions embedded below (questions are #3,4,6):
> 
> Hybrid board to be done:
> 1) need to match q1/q2 to get quad
> ...


----------



## luvdunhill

If you're unsure of the orientation of any part, pull out the schematic and trace each pad to some other component or signal on the board. Then compare to the schematic. This way, you don't rely on the silkscreen or forums, both of which have been known to be wrong at times.


----------



## FrankCooter

I appreciate all the positive comments! I'm as much or more a woodworker as an audio hobbyist. In answer to a few questions, the case is solid quarter sawn zebrawood with wenge accents. I'm very fortunate to be friends with a local hardwood supplier who specializes in artisanal grade lumber. The zebrawood came from a single 7" wide board that was glued into a panel and then surfaced in a wide belt sander. The joints are spline mitered. External dimensions of the case are 8"wide by 11" tall by 17" deep.
  The amplifier itself is a separate assembly that slides into the case like a drawer. A lot of materials and work, but a lot of satisfaction in the end result.
   
  Heat has not been an issue so far. The bottom of both the case and the amp is open. The amp boards are mounted on 1/2" offsets. There is generous air space around the boards, and the back is also open. Eventually I intend to convert the amp to the tubed version. If heat becomes a problem ( I don't think it will be), I'll add some more ventilation slots or inlay some sort of grill into the top.
   
  I like to view casework as a completely separate project, rather than an afterthought to the amp. I have, however, built plenty of "Bud Box" projects in my time and there's nothing wrong with that. I greatly enjoy seeing all your amps!


----------



## cat6man

Quote: 





luvdunhill said:


> If you're unsure of the orientation of any part, pull out the schematic and trace each pad to some other component or signal on the board. Then compare to the schematic. This way, you don't rely on the silkscreen or forums, both of which have been known to be wrong at times.


 

 thanks.........that in fact, is what i did (trace vs. schematic) and all the devices are now mounted.
   
  my next issue is heat sinks...............i have seen mention of grounding heat sink pins but my heat sinks have no pins, so i am confused here.
  also, are the heat sinks mounted with screws through the board?  i have some screws from the BOM but they don't seem to fit the heat sinks.
  i'll have to recheck the part numbers when i get home.


----------



## digger945

Quote: 





frankcooter said:


>


 


 Reminds me of something from Dune. Very nice.


----------



## cat6man

i also see arrows silkscreened next to each heat sink and what looks like a point for grounding (?) near a couple of them.
   
  can someone tell me what those are for?


----------



## runeight

cat6man, if you are using the newest boards, from the July board run, then all you have to do is to solder the pins of the heatsinks to their pads. If the heatsinks don't have pins, then you'll have to tap them and screw them to the board to make good metal contact between the heatsinks and the pads. It might be easier though to just get heatsinks with solder pins.


----------



## cat6man

any recommendations for size of tap and screws?
   
  if i get new heatsinks, is there a different part number for the pinned heatsinks?


----------



## runeight

Hmmm. Now that I think about it, tapping will require you to drill out the holes for a 4-40 screw. And this will damage the pads.
   
  It looks to me that this particular part in the BoM has the wrong part number. They are Wakefield heatsinks and they don't have pins. I wonder if anyone else is having this problem?
   
  Looking through Mouser I can't find an Aavid heatsink that has the right size.
   
  Let me check on this further.


----------



## TimJo

Unless something has changed, we used  Wakefield 637-20ABP in the last run of boards and they did have pins.


----------



## runeight

Yes, and this is why I am a bit confused. The Mouser catalog now seems to show them as pinless and the data sheets from wakefield don't come up.
   
  Has anyone else ordered these parts from Mouser?


----------



## pidesd

yes i did 4 days ago and got the right ones.


----------



## pidesd

is it a good idea to put a switch on the secondary 6.3V of my power transformer in order to power up the tube heater before applying voltage 300V, so to increase the chances of longer tube lifetime? or if i want the delayed power up, heater should have it s own transformer?


----------



## bidoux

I finished my eXstata today and it works fine.
   
  I just wanted to thank Alex Cavalli for designing and supporting it, you made a great and really easy to build project (the well-designed boardd help a lot). Thank you Frank Cooter for the Stax jacks, I would have had trouble finding them (great solid-state build by the way). And of course thanks to the others who have helped me during the build and help creating the amp !


----------



## cat6man

this looks similar with pins
   
  http://www.aavidthermalloy.com/cgi-bin/stdisp.pl?Pnum=530002b02500g
   
  just ordered these from digikey, part @
   

 HS380-ND      HEATSINK TO-220 POWER W/PINS BK
   
   
   

   
   
  edt:  i'm an idiot............these heatsinks are too large (wrong size, duh, but at least they have pins)


----------



## pidesd

Quote: 





cat6man said:


> this looks similar with pins
> 
> http://www.aavidthermalloy.com/cgi-bin/stdisp.pl?Pnum=530002b02500g
> 
> ...


 
  someone correct me if i m wrong,  but these are not needed for the hybrid build. those are the good ones.
   
  http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=HS382-ND


----------



## bidoux

Before I close the case of my eXStata : what kind of ground wiring is recommended ? I simply wired the earth to the common ground, is it correct ?
  This is less important as I can change it whenever I want : what size of fuze should I be using ? I am using 500mA quick-acting fuses. Before, I tried 315mA quick-acting ones but they blew each time I powered the amp on. Is it because of inrush-current (big caps) ? Should I try smaller fuse with a delay ?


----------



## cat6man

Quote: 





pidesd said:


> someone correct me if i m wrong,  but these are not needed for the hybrid build. those are the good ones.
> 
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=HS382-ND


 
  you've lost me now...................pins are not needed for the hybrid (which i am building)?


----------



## ujamerstand

Pins are preferred for q11&12 heatsinks because you can solder the pins to pads (which are connected to ground) to avoid oscillations.


----------



## pidesd

bidoux:
   
   fast blow fuses cant tolerate every kind of in-rush current. i d try a slow blow fuse first mon ami


----------



## cat6man

progess continues and my luck turned a bit..........while awaiting heatsinks with pins (to arrive later this week) and some more 2 position terminal
  connectors (somehow i'm short 4), i got my daughter to help me see if i could get a matched quad of J271s.
   
  i set up with a little experimental test board and used an old 9V wall wart supply to generate the 12V (came in at about 12.2V, while a 12V wall wart
  was over 15V).........another example for my wife why we should never throw out old electronics..........never know when an old wall wart will come in handy.
  i had 25 devices and was getting pretty concerned when only 6 devices measured over 10mA, but within those 6 i got lucky with the following:
   
  12.3
  13.4
  14.2
  13.1
   
  so those are now on-board.
   
  [also a good science experiment for kids, collect data, identify mean and maximum delta of quad]
   
  guess i'm on hold for a few days awaiting remainder of parts
   
  cheers


----------



## TimJo

Quote: 





bidoux said:


> Before I close the case of my eXStata : what kind of ground wiring is recommended ? I simply wired the earth to the common ground, is it correct ?
> This is less important as I can change it whenever I want : what size of fuze should I be using ? I am using 500mA quick-acting fuses. Before, I tried 315mA quick-acting ones but they blew each time I powered the amp on. Is it because of inrush-current (big caps) ? Should I try smaller fuse with a delay ?


 
   
  Yes, you're grounding sounds correct. The earth connection coming from the outlet should be attached to star ground. 

 I've been using 1 amp slo-blo fuses with 120 a.c., so I'd say 500ma slo-blo should be fine especially if you aren't having any problems with the fast ones.
   
  I can't remember what the recommended values were to tell you the truth, and haven't bothered to play around with it. Maybe someone else will chime in...


----------



## pabbi1

I always use 1A slo-blo, and still have in the same one from first power on last fall.


----------



## bidoux

Thank you all for your answers. I'm going to try less than 500mA slow fuse, the smallest, the more protection, right ?
   
  Last night, I managed to shorcut the AC live to ground with a screwdriver. It made some stuff melt 
	

	
	
		
		

		
			





 I have to close this case fast so I don't blow anything else.


----------



## cat6man

alex,
   
  i've been wondering about the volume pot................i have a TacT rcs2.2xp (used for room correction to speakers and for re-clocking all digital inputs)
  and a wadia 27ix, both with high quality digital volume controls as well as a logitech touch with digital output set at max.
   
  i typically run the wadia at max and use the TacT as my (remote) volume control.  i'm thinking of installing the volume pot but not wiring it in right now
  and replacing it with a fixed resistor, with the digital part of my audio system providing the volume control (or maybe wiring it up both ways with a mode switch).
   
  any thoughts on the value of the resistor(s) to replace the volume pot?


----------



## runeight

Use something like 47k. Big enough to be a good load, but small enough to keep noise down a little.


----------



## cat6man

heatsinks with pins just came in today from digikey.
   
  just to confirm, only Q11/Q12 heatsinks on the hybrid amp board need to be grounded?
  none on the power supply board?


----------



## cat6man

good news, heat sinks came from digikey
  bad news, the heat sinks are too large (how did i do that)
  good news, i found a work around
   
  at home depot stores, in hardware department, they have 'tension pins', 3/32" x 1/2" which are perfect.
  a small hammer and these are nicely inserted into heat sinks, and voila, pins!
   
  back to the soldering as soon as my wife gets off a phone call and i can have the air conditioned kitchen
  table area back
   
  update:  find i'm one short on heat sink mounting kits...........i checked the BOM on arrival, so i must have
  accidentally disposed of one.............i have one local option to try tomorrow..............oh, so close!


----------



## pabbi1

So quiet - listening to my eXStatA while building a new prototype. And waiting to hear some responses... certainly there are more than a couple of builds almost done?
   
  OY!


----------



## ujamerstand

Quote: 





pabbi1 said:


> So quiet - listening to my eXStatA while building a new prototype. And waiting to hear some responses... certainly there are more than a couple of builds almost done?
> 
> OY!


 

 Built a epsilon24 power switch unit today.  Still need to make a mouser order for some caps, but I need to create a mouser BOM for EHHA rev.A as well. Hoping to get a working exstata hybrid by the end of next week.


----------



## marcus1

I'm almost done and have just tested the amplifier board but seem to have a problem with the right amp so would greatly appreciate some help trying to solve the problem.
   
  Using the procedure from Cavelli Audio web site to test the amp board, I've come up with the following readings:
   
*Rail Voltages*: both +/- are 308V
   
*Left Amp:*
 * Voltage between output terminals adjusts OK using P2: varying between 0V to 0.15V
  * Output+ to gnd: varying between 0V to 0.15V
  * Output- to gnd: varying between 0V to 0.13V
   
  Heatsink of Q14L hotter than Q13L
   
*Right Amp:*
  * Cannot adjust voltage between output terminals to lower than around 15V (P2 at it's limit). Voltage is varying between 14.5V to 15.5V
  * Output+ to gnd: varying around 15.5V
  * Output - to gnd: varying between 0V to 0.5V (??)
   
  Heatsink of Q13R hotter than Q14R (opposite to left amp)
   
  Also:
  My input jfets readings are paired at 10.6 & 10.8 and 11.2 & 11.49 but didn't note which side got what.
  The heatsinks at Q11/Q12 L&R are grounded.
  I'm using a 369JX transformer which is quite warm to the touch - don't know if this is normal.
   
  Is it a clue to whats wrong with the difference between Out+ to Out- (to gnd) on the right board (15.5V and 0.5V respectively)?
   
  cheers
   
  Tim
   
  Quote: 





pabbi1 said:


> So quiet - listening to my eXStatA while building a new prototype. And waiting to hear some responses... certainly there are more than a couple of builds almost done?
> 
> OY!


----------



## chinsettawong

Hi,
   
  I am having a very hard time finding P Channel 500V Mosfet around here.  This is the only component that I can't find.  Can someone who has some extras share with me? 
   
  On the other hand, can I run the amp without using regulated supply?  How many mA does this amp draw in total?
   
  I would really appreciate any help.
   
  Wachara C.


----------



## tomytank

Wanted to say thanks again to all and Alex.  
   
  I've had the SS eXStata running since last Friday, waiting on some hook-up cable to replace what I'm currently using and a better attenuator before it's finished. Still need to build the final case. 
   
  I think I prefer the SS to the Hybrid-not sure why, still listening to both. But I like the SS sound.  
   
  chinsettawong - I have one P-channel 3P50 500V spare if you PM me your address, I'll send it to you.


----------



## pidesd

chinsettawong:
   
  i think it s 30ma and 35ma. you can check on the website
   
  marcus1: what is the voltage drop across the PSU s resistor R1?
   
  what about adjusting p1 on the amp boards?


----------



## noobula

I agree.


----------



## ujamerstand

Quote: 





noobula said:


> I agree.


 
  Dear sir, I find your opinion deeply insightful, and I wish to subscribe to your newsletters.


----------



## chinsettawong

Hi tomytank,
   
  Thank you very much for your generousness.  I will send you a PM.
   
  Wachara C.


----------



## ujamerstand

^^you could always use a MTP2P50EG in that position, people had success with them. Farnell has some in singapore.
   
  Actually, or this: http://cgi.ebay.com/Power-Mosfet-P-CHANNEL-FET-3P50-500V-3A-18nC-9-5pF-x2-/180509125144


----------



## gilency

You guys are great. I received the connectors from Frank today. Everybody helps...  I am just amazed at this community.
  BTW, I just started my first Cmoy (actually 2 of them)......in between 120 + hours of work last 14 days.
  I figure I'd try that before going with the eXStatA build..I am starting to look for parts and having Pabbi's proto will help me a lot by comparing while I build my own
  Sorry it is going to take me much longer than you guys. 
	

	
	
		
		

		
			





     _*hides his face in embarrassment*_


----------



## runeight

Quote: 





marcus1 said:


> I'm almost done and have just tested the amplifier board but seem to have a problem with the right amp so would greatly appreciate some help trying to solve the problem.
> 
> Using the procedure from Cavelli Audio web site to test the amp board, I've come up with the following readings:
> 
> ...


 


 First thing would be to check that all the right parts are in the right places on the bad channel. Your fets are not that far apart, but there has been one other case that I know about where the tolerance accumulation in all of the part required replacing fets.
   
  If all parts are correct then we might need to take a few measurements.


----------



## tomytank

Chinsettawong,
   
  Sent this morning, please look out for it.
   
  Quote: 





chinsettawong said:


> Hi tomytank,
> 
> Thank you very much for your generousness.  I will send you a PM.
> 
> Wachara C.


----------



## chinsettawong

Hi Tomytank,
   
  Thank you so much.  I really appreciate it.
   
  Wachara C.


----------



## pabbi1

If anyone is still needs 6s4a, I have another batch - just have to sort and test, along with a bunch of other triodes.
   
  Oh, and a little pron, just for good measure.


----------



## sachu

nice going Al!!
	

	
	
		
		

		
		
	


	



   
  I brought out the a set of exstata SS boards I needed to test out as well today.

 Going to try and test them out later tonight. Which reminds me..Brian..you get those SS boards out to me yet?!


----------



## ujamerstand

That does not look like an exstata. "Purple Haze", is that the name of the commercial electrostatic amplifier by Cavalli Audio?


----------



## pabbi1

No, this is a prototype of something quite different... just letting you guys know I'm not slacking. Pics with the purple case tomorrow after my finish dries. Don't think this ever sees the light of day as Commercial nor DIY - mainly because the tubes are already really scarce.
   
  But, this is the origin of 'Purple Haze' (purpleheart):


----------



## les_garten

Pretty sweet Kewlio!


----------



## Beefy

Quote: 





pabbi1 said:


> If anyone is still needs 6s4a, I have another batch - just have to sort and test, along with a bunch of other triodes.
> 
> Oh, and a little pron, just for good measure.


 


 New power supply?


----------



## wink

Love the Stax 5 pin socket.......


----------



## ujamerstand

I need an opinion sort of thing again. This time is about the way to mount R31~R34 for the hybrid version. I see three choices here:

   
  To all the hybrid builders out there, how are you mounting your R31-R34?


----------



## cat6man

good progress tonight.........power supply came up perfectly, LEDs lit when they were expected to and outputs measuring
   
  311 and 305 V output
   
  and
   
  327.4 and 328 volts at t1 and t3 testpoints.
   
  bias adjusted high to 580 for stax pro and 230 for stax normal. i have a little more wiring to do on the hybrid board (6.3v heaters, heat sink ground wires, input and output signals, volume control) so i probably won't get to music for another day or two
   
  question #1: my antek toroidal transformer has dual set of 6.3V output wires. should i use one set for 1/2 the tubes, 2nd for the other tubes?
   
  question #2: for the star ground, should this also connect the A/C ground wire/chassis?


----------



## Beefy

Quote: 





cat6man said:


> question #2: for the star ground, should this also connect the A/C ground wire/chassis?


 


 Yep. Good idea to connect it through a ground loop breaker though.


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> I need an opinion sort of thing again. This time is about the way to mount R31~R34 for the hybrid version. I see three choices here:
> 
> 
> To all the hybrid builders out there, how are you mounting your R31-R34?


 

 I go vertical on the resistors, then angle the leads down.  Opposite of your #2 sketch.  I also use a round set of needle nose pliers to hold the lead near the resistor to keep from cracking it.


----------



## cat6man

oh, so close......... hooked up the power supply to the hybrid amp (no connection to either inputs or outputs though) and no smoke, which is a good start.
   
  rails are at or above 300V, as they were with the dummy load on power supply, and all tubes are biased and glowing nicely.
   
  however:
   
  measuring each amp board i get 12v and 20v between each of the two output pairs, no way adjustable to below 1v with P2
   
  measuring one output side to ground i get over 100v on each, which convinced me something is definitely wrong.
   
  any ideas?
   
  do i need to load either the input or output before making these measurements?


----------



## cat6man

oh, so close......... hooked up the power supply to the hybrid amp (no connection to either inputs or outputs though) and no smoke, which is a good start
   
  measuring each amp board i get 12v and 22v between the two output pairs, no way adjustable to below 1v
   
  measuring one output side to ground is get over 100v on each, which convinced me something is definitely wrong.
   
  any ideas?


----------



## cat6man

i can make measurements or send pix if needed
  thanks


----------



## ujamerstand

Quote: 





boilermakerfan said:


> I go vertical on the resistors, then angle the leads down.  Opposite of your #2 sketch.  I also use a round set of needle nose pliers to hold the lead near the resistor to keep from cracking it.


 

 Too late.  I've tombstoned them yesterday.


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> Too late.  I've tombstoned them yesterday.


 

 No big deal.  I just do the angled lead to minimize the lead length.


----------



## gilency

Closer and closer to start my SS. My first ever amplifier (a Cmoy of course) went without a hitch. Building a better one next (JDS labs) before I start my eXStatA.
  Many thanks to Frank Cooter for the Stax connectors.


----------



## rhester

Anybody have a WIMA MKP10 100n 1kV cap they can sell (out everywhere) and a matched qaud of J271 (bhought 25 and only got 2 with I above 10 Ma). Really want to finish this amp and play with stax.


----------



## pabbi1

Beefy: Yes, new PSU, well, and new everything else as well.
   
   
  Finally tested all the tubes, discarding anything not 100%, and setting aside the 6s4 (free to anyone that wants them - just pay shipping).
   
  There are the following quantities of 6s4a, all with boxes:
   
  15 Sylvania
   7  Westinghouse
   8  GE
   
  Any quantity of the above: $3 each plus shipping.
   
  17 RCA - $3.75 each plus shipping.
   
  Note that some (not all) are dirty, which may require cleaning pins and glass.
   
   
  Catman6: Were that I could offer assistance, but troubleshooting is my greatest weakness.


----------



## ujamerstand

Just want to drop in and say I hate chassis work. Been wasting the whole night rearranging the components inside the chassis to a sane layout...
   

   
  Still need to reinstall CorelDraw on this computer to finish the logo too.


----------



## cat6man

Quote: 





pabbi1 said:


> Catman6: Were that I could offer assistance, but troubleshooting is my greatest weakness.
> 
> yikes..............i'm an electrical engineer but my background is math and communication theory (i'm working on next generation
> LTE mobile phone systems) so i am out of my depth with circuits that include more than resistors.
> ...


----------



## marcus1

I checked all the components and they seemed to be correct so, after checking with another eXStata builder (thanks Wil) who had similar problems, I swapped the jfets in the bad channel to another matched pair of jfets and thankfully this seemed to fix the problem 
	

	
	
		
		

		
			





.
  Prior to the swap I couldn't adjust the voltage between output terminals to lower than around 15V (P2 at it's limit) - now, with the new jfets, I can get it down to 0V.  It still doesn't seem as stable as the good left channel (the voltage can vary from 0V up to 2V even after being on for a few hours), but I'm happy because it is one excellent sounding amp!
   
  Cat6man:  Here are some posts that helped me when I was having similar problems:
   
  Offset/balance voltages incorrect: http://www.head-fi.org/forum/thread/447950/exstata-diy-electrostatic-amp-for-intermediate-diyers/2445
   
  Offset testing: http://www.head-fi.org/forum/thread/447950/exstata-diy-electrostatic-amp-for-intermediate-diyers/1380
   

   
  Quote: 





runeight said:


> First thing would be to check that all the right parts are in the right places on the bad channel. Your fets are not that far apart, but there has been one other case that I know about where the tolerance accumulation in all of the part required replacing fets.
> 
> If all parts are correct then we might need to take a few measurements.


 




  Quote: 





marcus1 said:


> I'm almost done and have just tested the amplifier board but seem to have a problem with the right amp so would greatly appreciate some help trying to solve the problem.
> 
> Using the procedure from Cavelli Audio web site to test the amp board, I've come up with the following readings:
> 
> ...


----------



## FrankCooter

cat6man, did you ever resolve your problems? Do you still need help?


----------



## wink

Quote:cat6man, did you ever resolve your problems? Do you still need help?
  We all need help .... badly.
   
  If only I knew more bank managers and benevolent billionaires......


----------



## HeadphoneAddict

Quote: 





wink said:


> We all need help .... badly.
> 
> If only I knew *ANY* bank managers and benevolent billionaires......


 

 FIFY


----------



## ujamerstand

After double, no, triple checking each solder joint, I've wired up the power supply for testing and successfully biased the power supply to +300V and -300V on each side of the rails. Quite happy right now. There is one thing I want to mention though, while measuring T1 to ground, epsilon24 would trip and turn the amp off. This does not happen with T3 in respect to ground. (both measurements are around 350~354V) What might have caused the relay to trip?
   
  Edit 1: heater and the tubes are ready to go. Wiring up the amp section and soon everything will be wired up.
   
  Edit 2: It is working! ugh. The reading between the two output terminals changes between 2.3V and -1.9V... Is this oscillation I'm looking at right now?


----------



## ujamerstand

Well, now I have everything wired up and running. However, I cannot get the offset to stabilize around 0V. The offset between the two terminals still oscillates between +3.2V 5.2V and -1.8V in around a minute. It slowly increases and slowly decreases. I've grounded the heatsinks already. Any Idea whats going on? How fast does the offset drift for all the other builders out there? 
	

	
	
		
		

		
		
	


	




" class="bbcode_smiley" height="" src="http://files.head-fi.org/images/smilies//http://hfimage.head-fi.org/smilies/frown.gif" title="
	

	
	
		
		

		
		
	


	




" width="" />
   
  I should mention that I am using quad SJ74BL fets matched at 10.91, 10.91, 10.91, 10.93 Idss for the input and 2sc3676s for the output devices. All the heatsinks are warm to the touch.


----------



## sachu

if it settles between +/-2V from 0 after a minute or two, you are fine.


----------



## ujamerstand

Oh. Well, let me plug it in!


----------



## runeight

If the voltage is fluctuating slowing then it is just thermal drift and shouldn't be a problem if it stays within that range. Once the amp has some burn-in time it should be a bit more stable.
   
  What relay is tripping?
   
  Edit: Alas, the rule is always check for newer posts before you make your next post.


----------



## ujamerstand

Well, the power switch is powered by an epsilon24, which controls a relay that delivers mains to the powersupply.. Epsilon24 would trip the relay when I am measuring the voltage between T1 and ground, and when I am adjusting the boas voltage. I asked amb about this, and he replied that the relay would trip if DC offset is created as a side effect of taking measurements. 
   
  Anyways, I've plugged in the headphones. It works like a charm! Tonight marks the first time that I'm able to listen to my Stax SR-404. Perhaps it's because I haven't been listening to headphones a lot recently, but this setup sounds REALLY good to my ears right now. Boards of Canada has never sounded better! I should probably start fixing that logo right now, but I think I'm going to leave that and clean up till tomorrow, this stuff is too good to be shut down right now.


----------



## sachu




----------



## ujamerstand

Bah. I'm experiencing tracking issues with the dantimax relay attenuator. The attenuation jumps in volume as I turn the pot from time to time. I remember going through each and every level of attenuation and checking the resistance of the cable for shorts. This is not cool at all. This thing is not going into my exstata.


----------



## runeight

Quote: 





ujamerstand said:


> Well, the power switch is powered by an epsilon24, which controls a relay that delivers mains to the powersupply.. Epsilon24 would trip the relay when I am measuring the voltage between T1 and ground, and when I am adjusting the boas voltage. I asked amb about this, and he replied that the relay would trip if DC offset is created as a side effect of taking measurements.
> 
> Anyways, I've plugged in the headphones. It works like a charm! Tonight marks the first time that I'm able to listen to my Stax SR-404. Perhaps it's because I haven't been listening to headphones a lot recently, but this setup sounds REALLY good to my ears right now. Boards of Canada has never sounded better! I should probably start fixing that logo right now, but I think I'm going to leave that and clean up till tomorrow, this stuff is too good to be shut down right now.


 


 DC offset where? I'm sorry, I just want to get this right.


----------



## ujamerstand

Actually, what he said was AC voltage spike. It was late last night, and my mind was unraveling at that point. Sorry about that. I'm guessing that measuring the bias voltage caused a voltage sag that in turn, caused epsilon24 to trip. Does measuring T1 or T3 to ground on the PS cause a AC voltage sag as well?


----------



## runeight

Quote:


ujamerstand said:


> Well, the power switch is powered by an epsilon24, which controls a relay that delivers mains to the powersupply.. Epsilon24 would trip the relay when I am measuring the voltage between T1 and ground, and when I am adjusting the boas voltage. I asked amb about this, and he replied that the relay would trip if DC offset is created as a side effect of taking measurements.
> 
> Anyways, I've plugged in the headphones. It works like a charm! Tonight marks the first time that I'm able to listen to my Stax SR-404. Perhaps it's because I haven't been listening to headphones a lot recently, but this setup sounds REALLY good to my ears right now. Boards of Canada has never sounded better! I should probably start fixing that logo right now, but I think I'm going to leave that and clean up till tomorrow, this stuff is too good to be shut down right now.


 

 You know, I was so concerned about a possible problem I forgot to say congrats on getting the amp to work!!! Glad you like it. Maybe you can give us more reviews on how it's doing with your favorite music.


----------



## rhester

Is the KSC5042FTU a suitable substitute for KSC5042FYDTU? Only thing left at Mouser.


----------



## runeight

Yes, You can also use KSC5027.


----------



## ujamerstand

Quote: 





runeight said:


> You know, I was so concerned about a possible problem I forgot to say congrats on getting the amp to work!!! Glad you like it. Maybe you can give us more reviews on how it's doing with your favorite music.


 
  Thanks! Couldn't have built it without the community support. 
	

	
	
		
		

		
		
	


	




" width="1" />
	

	
	
		
		

		
		
	


	




 It is not entirely finished yet though. I really should clean up the bird nest of a wiring job inside the amp, drill pcb mounting holes into the chassis, finish designing the front panels, and organize everything into a neat package... As of now, I'm hearing a very slight hiss with the dantimax attenuator, while this does not happen with a RK27. I think the dantimax is out of the equation until I replace its power supply with a better one, and debug the attenuator section to figure out whats causing the jumps in volume. I don't think a review for this amp at this stage is really fair, I think I should do that after I've everything sorted out. 
	

	
	
		
		

		
		
	


	







" width="1" />


----------



## ujamerstand

made some progress on the logo.


----------



## HiGHFLYiN9

Nice looking plate there Umjamerstand!
   
  I'm in the process of putting together this BOM and, of course, Mouser seems to be completely out of all the required parts from Fairchild Semiconductors  Guess I'll be checking out Digikey.


----------



## gilency

DigiKey doesn't have either. Where else can you get the Fairchild from?
  They don't have the Trimmer Resistors either (3296W-1-101LF)


----------



## runeight

Looking quickly, the J271 and KSA1156 are both in stock. I haven't checked the PS mosfets, but there should be subs in the Mouser catalog.
   
  You can sub KSC5027 for the KSC5042 (although  there appears to be 10 of these in stock right at this moment).
   
  So, all is not lost at Mouser.


----------



## sachu

mouser is out of  http://www.mouser.com/ProductDetail/WIMA/MKP10-1-1KV-10P22/?qs=sGAEpiMZZMuj6GhJEt2K7cL0RNaHDjHIskovCh85sRY%3d
   
  Do we have a replacement for this or does anyone have extras??


----------



## ujamerstand

I bought mine from TAW electronics. Give them a call or email, they respond quickly and the people there are quite friendly. MKP10 .1/1000/5%-22.5MM is the part number I believe.


----------



## sachu

thanks buddy. will do.


----------



## studeb

TAW has the 10% version in stock


----------



## cat6man

@wink
  @frankcooter
   
  hi,
  i still have problems but am going to try to learn some transistor 101 first (it has been a long long while) and see
  if i can figure it out. (wishful thinking?)
   
  i may ask for some voltage measurements from someone with access to a hybrid for comparison.
   
  i'm sure the facts that a) both sides behave the same and b) i'm getting 100V from output to star ground
  are pretty big clues........either something was done wrong on both boards identically or something
  similar died (poor handling of static sensitive devices??) but 100V at each outputs to ground should be a biggie.
   
  another option is to bring it into one of our labs at work and have some 'transistor' buddies look at it..........they
  build high power transmitters and low noise preamps for a living, so this should be easy for those folks
   
  thanks again for asking, and i'll let you know how it goes and if i need more help here.
   
  best


----------



## studeb

i saw that mouser seems to be out of all fairchild parts, esp for this amp.
  Are they available elsewhere?


----------



## ujamerstand

cat6man, let me know if you need any voltage measurements from my hybrid.
   
  studeb, mouser has MPSA92 from other manufacturer in stock. digikey has MJE340 and MJE350 in stock. You can find the N channel mosfet on ebay.


----------



## chinsettawong

Hi,  
   
  I've finished putting everything together.  When testing the amp, sometimes I can adjust the two output terminals down to zero, but once in a while the voltage on these terminals jumps up to around 190V.  I noticed that if I touch the input terminals using the probes of my multimeter, the voltage on the output terminals go back down to where it should be.  I'm confused.  Is this oscillation?  Do hybrid boards require grounding of the heatsink?
   
  Wachara C.


----------



## HiGHFLYiN9

Quote: 





studeb said:


> TAW has the 10% version in stock


 

 Looks like they're fresh out of both now. I may have to wait a month for mouser to restock as I can't find it elsewhere.
   
  Boy, that TAW website is about as unintuitive as they come.


----------



## sachu

^^ buggers..for real?? Are there no other alternates for this part? Can we use this cap instead?


----------



## ujamerstand

^^ I've got that one. It was too fat.
   
  Did you try emailing them? The website may not reflect their real inventory...


----------



## sachu

i should be able to mount the two diodes on the bottom of the board and slot it in somehow. I called TAW..no dice on the ones on the BOM. In any case, i just ordered 4 of the fatty ones..all i got now is hopes and dreams that I will be able to fit tem on the board unless there is some other alternative. Should possibly check other vendors. Vishay and kermet are out of these caps too.


----------



## sachu

I should think we might be able to get away with a polyester cap in this position eh? Something like this maybe?


----------



## sachu

hmm some serious diggin in my parts bin and i came up with one of the BOM capacitors..anyone got another?  And i went ahead and cancelled that TAW order for the fatty MKP10 ones.


----------



## ujamerstand

I think I got 2 lying around... I was going to use them for a T2 style bias supply, but since the onboard one seem fine after listening to it for days, I don't think I'll need them anymore. I'll see if I can find them when I get home.


----------



## sachu

^^ sweetness!!..thanks dude


----------



## ujamerstand

It turns out I got 4 of these things lying around. 3 5% and 1 10%.  This cap is for the C6 position on the power supply. If anyone needs them I'll gladly pass them on.


----------



## HiGHFLYiN9

Can I trouble you for one ujamerstand? ygpm.


----------



## drclaw

YHPM ujamerstand.


----------



## ujamerstand

All caps have been spoken for. I'll ship them tomorrow.


----------



## ujamerstand

All caps have been shipped. Good luck on your porjects guys.


----------



## rhester

Anybody have any spare 6 pin connectors or know where to get them besides Allied (out of stock for a while)? And does abybody have a matched quad of J271 to sell - I have bought 50 and could not get 4 over 11mA and 10% tolerance?
   
  Any help appreciated. I can't wait to listen to this amp.


----------



## sachu

Just use 2 3 pin connectors.
  Hit up Luvdunhill for a set of matched JFETs.


----------



## ujamerstand

Remember that new york guy I talked about? I found him. http://www.leedselect.com/ go to connector section and search for stax.


----------



## pabbi1

Quote: 





rhester said:


> Anybody have any spare 6 pin connectors or know where to get them besides Allied (out of stock for a while)? And does abybody have a matched quad of J271 to sell - I have bought 50 and could not get 4 over 11mA and 10% tolerance?
> 
> Any help appreciated. I can't wait to listen to this amp.


 

 Mayhaps I'll have some connectors to distribute - more on the weekend.
   
  Still a few tubes left.


----------



## steven2992

Quote: 





rhester said:


> Anybody have any spare 6 pin connectors or know where to get them besides Allied (out of stock for a while)? And does abybody have a matched quad of J271 to sell - I have bought 50 and could not get 4 over 11mA and 10% tolerance?
> 
> Any help appreciated. I can't wait to listen to this amp.


 

  
  If you're in europe I have some connectors for you.


----------



## cat6man

Quote: 





ujamerstand said:


> cat6man, let me know if you need any voltage measurements from my hybrid.


 

 hi there,
   
  i would be very grateful if you could measure
  1.  the dc voltages you see on the heatsinked transistors which should be accessible from the top of the board (q11-16)
  2.  tube voltages which connect to (R21/25, R22/28), (grid at R37 and R38), collectors of Q5/Q8
  3.  any Q1-10 voltages that are accessible
   
  my V=I*R skills should get me around the rest of the circuit if i know what is going on with the transistors
   
  thanks in advance for the help!
   
   
  and the


----------



## ujamerstand

Cat6man, talk about bad timing. My exstata currently sit disassembled as I do work on the chassis. I should have everything back and running next weekend... In the mean time, could you elaborate more on what you wanted to measure?
   
  1) From which pin to which reference?
  2) You want the measurements of the plate to the collectors of Q5/Q8, and the gride to the collectors?
  3) Again, which pins to what reference?


----------



## cat6man

Quote: 





ujamerstand said:


> Cat6man, talk about bad timing. My exstata currently sit disassembled as I do work on the chassis. I should have everything back and running next weekend... In the mean time, could you elaborate more on what you wanted to measure?
> 
> 1) From which pin to which reference?
> 2) You want the measurements of the plate to the collectors of Q5/Q8, and the gride to the collectors?
> 3) Again, which pins to what reference?


 

 no rush............i'll elaborate more (and better) later this week......basically looking for transistor measurements (all 3 pins) so i can check if the active devices
  are working properly, shorted, open, etc.


----------



## chinsettawong

Hi,
   
  I've been having this weird problem and I can't really find the reason.  Could you please help?
   
  On my PS board and Hybrid amp boards, I've managed to make the adjustments as per the instructions.   But sometimes, when I fire up the PS, one of the red led would not light up.  I have to use the probe of my multimeter to touch on T1 or T2.  The moment I touch it, the red light lights up.  Another similar weird problem that I have is on the Hybrid board.  Upon fired up, sometimes the voltage accross Out+ and Out- just isn't at 0V.  The voltage would measure at around 190V.  But once I use the probe of my MM to touch the In+, In-, and Ig, the voltage then comes down to 0V.  Can someone help me please?  What could have been done wrong?
   
  Wachara C.


----------



## gilency

I will be buying parts and start my SS soon. I would like to have 2 jacks, one for Pro and one for normal bias.
  Which other supplies do  have to buy? 
  Frank Cooter already  graciously sent me the 2 jacks.


----------



## ujamerstand

^^Stax headphone related stuff? That's about it. Other than that you might want to consider a 4-gang pot if you have a balanced source (something like the quad RK27 sold by ebay seller familygate is nice and cheap), xlr input connectors or rca connectors (or both controlled by a 4PDT switch), hookup wires rated over 600V, an enclosure from hammond, par-metal, hifi2000, vt4c... etc etc. Go nuts with it.
   
  @ Chinsettawong, its tough when you're experiencing issues. 
	

	
	
		
		

		
		
	


	




 I might not be much of a help. You asked if the heatsink on the hybrid needs to be grounded on the last page, the answer is yes. There are already traces on the amplifier section that links the heatsink pins to ground. If you haven't done so, try solder the pins to the board and see if the issue still occurs?


----------



## gilency

LOL.I meant, what else do I need to have 2 phone jacks. One of each, Pro and normal bias.


----------



## ujamerstand

You got the 6 pin WPI jack right? Pull out the center pin for pro bias, fill it up with epoxy so somebody's normal bias phones won't get damaged from accidental plug in. Then wire it up and stick it on the panel. Normal bias uses all 6 pins. I guess if you want something fancy you can do what audiocat did. http://www.head-fi.org/forum/thread/494097/tuitorial-how-to-make-a-wood-case-friendly-stax-socket-with-silver-plated-neutrik-contacts
   
  Edit: What the hell am I saying, you have both the sigma pro and sigma low bias. Honestly I'm not sure what you're trying to ask here. Sorry. You have the jacks already right? That's all you need. lol The board has two adjustable bias supplies that could be wired individually for normal and pro bias.


----------



## chinsettawong

Hi Ujamerstand,
   
  Thank you very much for your reply.  I really appreciate it.  It's weird that I have this problem alone out of so many people who have made them.  
	

	
	
		
		

		
			




   
  I had soldered the heat sink, but the problem didn't go away. 
   
  Wachara C.


----------



## ujamerstand

Hmmm.. The led would not turn on only when there are no current through it. You mentioned that the led lights when you touch T1 or T2, so this is on the positive rail, and the L1 does not light? 
   
  Also, does the two problem occur concurrently? I mean, is it the case that 190V offset occurs only when L1 does not light?  
   
  We should get somebody more experienced here to help debug your problem...


----------



## gilency

Quote: 





ujamerstand said:


> You got the 6 pin WPI jack right? Pull out the center pin for pro bias, fill it up with epoxy so somebody's normal bias phones won't get damaged from accidental plug in. Then wire it up and stick it on the panel. Normal bias uses all 6 pins. I guess if you want something fancy you can do what audiocat did. http://www.head-fi.org/forum/thread/494097/tuitorial-how-to-make-a-wood-case-friendly-stax-socket-with-silver-plated-neutrik-contacts
> 
> Edit: What the hell am I saying, you have both the sigma pro and sigma low bias. Honestly I'm not sure what you're trying to ask here. Sorry. You have the jacks already right? That's all you need. lol The board has two adjustable bias supplies that could be wired individually for normal and pro bias.


 
  As you can see, I am a real noob. I do have the jacks. For what you are saying, I just go ahead and wire them to the board. I was thinking I needed some extra parts (diods, resistors, etc).


----------



## studeb

Gilency,
   
  Are the wiring diagrams no longer on the Cavalli Audio website?
  Where in SoCal are you?


----------



## ujamerstand

Quote: 





gilency said:


> As you can see, I am a real noob. I do have the jacks. For what you are saying, I just go ahead and wire them to the board. I was thinking I needed some extra parts (diods, resistors, etc).


 

 You do need resistors and diodes for the bias supply, but that's already in the BOM. 
	

	
	
		
		

		
		
	


	




 If you didn't know already, this thing CAN kill. Getting zapped hurts REALLY bad. Please keep that deep in your heart somewhere. But do enjoy the build.


----------



## cat6man

Well, I finally found some time this afternoon to go down to the basement and make some measurements.
  I will post them later tonight when I have them in a more friendly format.
   
  However, I think I may have found the (a?) problem.  Q3 and Q4 are mounted per pcb silkscreen that shows one side of the device thinner
  than the other, looking from the top.  On the other hand, it is the wider side of these devices that shows a single dot in the upper left hand corner, which then does not match up with the silk screen.  So, what do you all think?  Is the dot location key for identifying the correct orientation or the taper as seen from the top?  Since both channels are misbehaving, I feel I'm looking for something common to both R and L boards, and this would fit the bill.
   
  On the other hand, this is in the differential input circuit, and it isn't clear to me that this could/should cause -100V to ground at Out+ and Out-
  so perhaps there is more than one problem.


----------



## studeb

Q3 and Q4 are not mounted facing the same way.
   
  Looking from the top, one long side is shorter than the other.
  That shorter side (with the marking IIRC) goes toward the close edge on Q3 and away on Q4.
   Look at the old thread posts 1266 and 1271, you can sort of see the orientation there.


----------



## gilency

Has anybody built the power supply in separate enclosure?


----------



## sachu

why do you need a separate enclosure for the PSU?


----------



## gilency

Quote: 





runeight said:


> Yes, You can also use KSC5027.


 

 did you mean the 512-KSC5027OTU ?


----------



## gilency

[size=medium] [size=10pt]I am missing the Fairchild FQP3P50. Any idea of where I can get it? is there a substitute?[/size][/size]
 [size=medium] If anybody has a spare, I'll be happy to buy it.[/size]


----------



## ujamerstand

I've got 2 lying around. But that's because mine is running fine with MTP2P50EG. So the spares from ebay are not used.


----------



## gilency

If you are willing to sell me one, please PM me. Thanks.


----------



## cat6man

Quote: 





studeb said:


> Q3 and Q4 are not mounted facing the same way.
> 
> Looking from the top, one long side is shorter than the other.
> That shorter side (with the marking IIRC) goes toward the close edge on Q3 and away on Q4.
> Look at the old thread posts 1266 and 1271, you can sort of see the orientation there.


 
  well, that is how i have them inserted, so off to look for another theory.
  i'll post measured voltages soon and maybe they'll provide the clue


----------



## gilency

my SS proto exstata has 2 triads that are kind of noisy.
  I am looking for a more quiet transformer  for my SS exstata build. Which one do you guys recommend? 
  I know I could use the 269JX just want to make sure is quiet.


----------



## ujamerstand

How noisy are the triads? Do you have to put your head near the transformer to hear a buzz? If so, I've got the same thing on my exstata. (using 269JX) You really have to place your ears in a certain angle to hear it... Some people would probably suggest 369JX, it should be less noisy, runs cooler, and you could configure it for 230VAC power line if you move to EU; but it is bigger, and cost goes up as well...


----------



## BoilermakerFan

Quote: 





gilency said:


> my SS proto exstata has 2 triads that are kind of noisy.
> I am looking for a more quiet transformer  for my SS exstata build. Which one do you guys recommend?
> I know I could use the 269JX just want to make sure is quiet.


 


  I assume you mean mechanical vibration noise.  I'm biased, but a shielded and fully encapsulated toroid from SumR is silent.


----------



## gilency

yes. do you have a specific one in mind?


----------



## BoilermakerFan

Quote: 





gilency said:


> yes. do you have a specific one in mind?


 

 They're all custom.  IIRC, The eXStatA is 480VCT @ 70mA.


----------



## gilency

Never mind. I think I will use the triads. They are cheaper.
  I ordered the rest of my BOM today.
  Already have all the Fairchild's.


----------



## sachu

Be prepared for a sizable jump in performance from the proto version. 
   
  You might want to consider using the Sanyo 2SC3675 instead of the fairchilds.. I plan to use them for my own build.


----------



## ujamerstand

I've had good luck with 2SC3676s. Thanks to boilermakerfan for suggesting them to me. 
	

	
	
		
		

		
			





 Be prepare to spend more than the default devices though.


----------



## gilency

Quote: 





sachu said:


> Be prepared for a sizable jump in performance from the proto version.
> 
> You might want to consider using the Sanyo 2SC3675 instead of the fairchilds.. I plan to use them for my own build.


 


  That is good to hear. Are you talking about the input JFETs? Where can I buy them?


----------



## ujamerstand

he's talking about the output devices, though you could replace the input JFETs with J74BLs. You can get them at http://www.mcmelectronics.com/ or http://www.bdent.com/


----------



## gilency

Started my SS tonight. So far uneventful soldering of resistors after careful matching within 5% of each other, checking and double checking before soldering. I am able to work on it only every 3 weeks so it will take me some time.


----------



## HiGHFLYiN9

I had a question regarding the diode direction. They sit up straight; with one end sitting on the circle on the PCB and the other lead in the air, which is bent and then fed through the other through hole. I didn't see any indication on the PCB for which end the black line is facing. Is it the end sitting on the PCB, or is it the end up in the air?


----------



## ujamerstand

http://www.cavalliaudio.com/exstata/main.php?page=instructions/assembly
   
  The diodes sit on the circle with the marked side facing upwards.


----------



## gilency

Hey guys, can I use:
   
71-RN60D-F-681 (http://www.mouser.com/ProductDetail/Vishay-Dale/RN60D6810FB14/?qs=sGAEpiMZZMu61qfTUdNhG33BaVfMIgUsntcPuWg9g24%3d)
  instead of 71-RN55D-F-681 (http://www.mouser.com/ProductDetail/Vishay-Dale/RN55D6810FB14/?qs=sGAEpiMZZMu61qfTUdNhG33BaVfMIgUsMM7ecPUkgRU%3d)?
   
  Is this dual Alps OK?: 688-RK27112A0A16 (http://www.mouser.com/ProductDetail/ALPS/RK27112A0A16/?qs=Xb8IjHhkxj7yFzrECyPQoA%3d%3d)? 
   
  Thanks!


----------



## sachu

yes on both accounts.
   
  That ALps will work if you are using the amp with SE inputs.


----------



## gilency

Thanks. How about the Alps RK27112 quad 50KA if I decide to go balanced?
  This thread http://www.diyaudio.com/forums/vendors-bazaar/168999-fs-alps-rk27-series-rk27112-dual-20k-b1-rk27114-quad-50k-balanced.html has them cheap.


----------



## gilency

double post.


----------



## sachu

sucks..mouser seems to be out of a lot of parts lately. They d have the mica insulator version which will work as well but you will need to apply thermal compound for each one of them. 
   
  I'd just go with the thermasils..Newark seems to have them in stock.
   
http://www.newark.com/jsp/displayProduct.jsp?sku=10M7230&CMP=KNC-OTH-SKU-OTH&s_kwcid=TC|14641|4880sg||S|b|5199945741


----------



## gilency

OK, I have 30 J271's but don't know how to match them with a multimeter. 
  how do you do this?


----------



## ujamerstand

I would recommend reading the exstata site throughly. All the information is there. Google is your friend as well. Search for J271's data sheet and look for its pin-out.


----------



## gilency

I read the exstata site and have googled for this, as I always do. I would appreciate some help. Thanks.


----------



## sachu

http://www.amb.org/audio/beta22/
   
  Look at device matching and you need the info listed under JFET matching.
   
  Alternatively, PM luvdunhill to see if he has any matched J271 quads left over.


----------



## gilency

Well, I managed to measure the J271's. It wasn't that hard once you understand what you  read 
	

	
	
		
		

		
			




  Thank you Sachu and Ujamerstand.
   
  Of the 30 purchased at Mouser, 20 had values below 10 mA, therefore useless.
   
  The rest were as follows:
  10.1:  1
  10.5:  2
  12.5:  1
  13.3:  1
  14.5:  1
  14.6:  1
  15.5:  1
   
  So I guess I better buy a hundred next time?
  On the other hand, if anybody has a few within the range of the ones I mentioned, or better yet, has a quad of matched J271's to sell me, please shoot me a PM.


----------



## wink

Isn't there something else we could use instead of this total waste of sand, the J271?


----------



## ujamerstand

2SJ74BL or LSJ74A I guess. Though you'll be hard pressed to find quads over 10mA as well. I simply got lucky and got a quad off a diya member.


----------



## gilency

So, are both 2SJ74BL or LSJ74A acceptable substitutes for the J271's?
  Are they any easier to match?


----------



## gilency

I ended up using the KSC5027 instead of KSC5042 for Q11-Q16 next to the heatsinks. I did not see a dot in it like in the silkscreen.
  Could you guys please tell me whether the orientation is correct or not?
  EDIT: upon reading the second page of this thread, runeight mentions thta the 5042's lettering should face aways from the heatsinks, so I assume this is also correct for the 5027's although would still like some reassurance. Thanks


----------



## ujamerstand

That is the correct orientation.


----------



## BoilermakerFan

Quote: 





gilency said:


> So, are both 2SJ74BL or LSJ74A acceptable substitutes for the J271's?
> Are they any easier to match?


 


  LSJ74s aren't released yet.  LS should have a few samples at Burning Amp 2010 in S.F. this year, but we'll see...  Definitely can't buy them on the LS web site that I could see.
   
  No, they are harder to match because most SJ74BLs are in the 7-8mA range.  Very few will be above 10mA and even far fewer above 11mA.  Plus they are more expensive since they are harder to get.  I ordered 120 out of China on diyAudio for the F5s, DACs, and phono stages.  I bought a matched quad that measured 10.8mA for my eXStatA that is now going to my Liquid Lightning design study instead...


----------



## gilency

I ended up using the 71-RN60D-F-681 instead of the 71-RN55D-F-681 because the latter one wont be available for months. I ended up tombstoning them however because they are a little bigger than the originals. I hope that is OK.
Ordered 100 J271's today. The only missing component of the amp boards. Otherwise is finished. PS is next, then the wiring. 
Anybody knows a good supplier in ebay for 600V rated  PTFE/Teflon wire?
One more thing, I have been using 91% IPA to clean the board because I can't find the 99% anywhere at home. It leaves an opaque coating on the PCB. Is that a problem?


----------



## gilency

I can't seem to be able to solder without R20-R21 or R17-!8 touching each other in the power supply (249k resistors).
  I did notice they do run in series in the schematic so assume it's fine.
  Could anybody tell me if that's OK or not?
   
http://www.cavalliaudio.com/exstata/images/eXStatA%20PS%20Rev%20B%20100.png
   
http://www.cavalliaudio.com/exstata/main.php?page=schematics/powersupply
   
  And why do R13 and R14 have a diode symbol if they are resistors?


----------



## Forte

Quote: 





gilency said:


> One more thing: why does the power supply silkscreen has R13 and R14 with a diode symbol? I thought it should be a resistor instead, since that is what the PS schematic shows (47K R)


 


  Have a look here http://www.cavalliaudio.com/exstata/main.php?page=schematics/maxedsupply


----------



## gilency

OK thank You. I did not read the maxed out power supply because I did not think it applied to what I have, but it is an easy enough option I'll go ahead with it.


----------



## sachu

^^ yes its fine..however, you asking such questions makes me nervous for you and this build.


----------



## gilency

Quote: 





sachu said:


> ^^ yes its fine..however, you asking such questions makes me nervous for you and this build.


 

 Don't be. Yes, I am pretty new to this but I can assure you I am double checking and triple checking every step of the process.


----------



## ktm

Here's a casing option for some of the new builders. A Nabu box with a cheap piece of wood from Lowes and a grate cut into the cover to vent.


----------



## gilency

The wood really dressed up the case. Very nice!
  Could yo post the H-W-D of the enclosure?


----------



## ktm

It was linked in one of the other exstata threads.
 Here's the info and where to get it.
 http://www.surplussales.com/cab-rackshardware/encl_2.html


----------



## gilency

I finished populating both the PS and SS boards, except for the darn J271's. I had to order 100 of them Hopefuly I'll get a matched quad.


----------



## gilency

Have any of you used these switches? 
  http://www.mouser.com/ProductDetail/Bulgin/MP0045-1E2GN012/?qs=sGAEpiMZZMvxtGF7dlGNplr9LVjb3l8KS%252bIz5FPAvA0%3d


----------



## BoilermakerFan

Quote: 





gilency said:


> Have any of you used these switches?
> http://www.mouser.com/ProductDetail/Bulgin/MP0045-1E2GN012/?qs=sGAEpiMZZMvxtGF7dlGNplr9LVjb3l8KS%252bIz5FPAvA0%3d


 

 Sachu and I use the non-illuminated version.  My only gripe is that the "off" position is with the button in and flush, not extended.


----------



## sachu

Not this one Brian. I use this.
   
http://www.mouser.com/Search/ProductDetail.aspx?R=MP0045/3E0NN000virtualkey15070000virtualkey117-MP0045/3E0NN000


----------



## gilency

After testing 130 J271's,
	

	
	
		
		

		
		
	


	




 I (finally) have 4 sets of matched quads:
   
  a) 10.0-10.43     b) 10.58-10.90       c) 11.32-11.86        d) 12.50-13.36
   
  Which ones should I use?


----------



## BoilermakerFan

C or D.  D is better since it's the highest group but the range is a little wider.


----------



## runeight

Quote: 





gilency said:


> After testing 130 J271's,
> 
> 
> 
> ...


 

 Sorry about this. We actually did test this some during the proto. IIRC everyone was able to find at least one quad in 20 jfets. Not a perfect statistical sample, but it seemed to hold pretty well for everyone. I was able to get several quads in two separate buys of 20 each.
   
  130 jfets is a lot to say the least.


----------



## pabbi1

Now I remember why I buy matched quads... it is good to have friends that do that sort of thing. Sounds like you are closing in on it Enrique...
   
  Ok, last call for 6s4a - I have about 20 odds and sods (RCA, Sylvania, GE and Westinghouse) - $25 shipped US.All NOS.
   
  I also have a half dozen 6s4, postage only.


----------



## gilency

Thank you, but mine is a SS. And BTW, your proto SS build has been invaluable as a visual guide.


----------



## pabbi1

My poor communications skills strike again - the tube issue was to any and all eXStatA builders.
   
  Still loving my eXStatA - just wondering where all these builds are, since it has been quite a while...


----------



## sachu

Al, I should have my personal exstata complete here in about 3-4 hours and will post pics once it is done Another SS exstata am building for my good friend Devin (dewild) in Portland will also be ready once the power switch comes in tomorrow. It will look identical to mine except mine will be using the luvdunhill digital attenuator while Devin's will use a quad quad Alps pot.
   
  Now I need to start saving up for an O2 ...or better yet the C32


----------



## sachu

Well just got done with my personal exstata..Al mins is running with the Sanyo 3675 that you generously donated to me, in lieu of the fairchild KSC5042/5027s...will post if i hear any differences as i got exstatas running both here.


----------



## sachu

Here are some pics of my amp that i just completed. Sounds pretty sweet..but now i find myself in the situation where i have no stat headphone to call of mine. Will need to start saving up . Currently am using an SR-404 on loan from dewild to help test his and my own exstatas.


----------



## BoilermakerFan

Normal bias Lambdas have an amazing synergy with the eXStatA.  Just saying so you can save $1K or more...


----------



## HiGHFLYiN9

Nice work Sachu! Looks like those conical bumpers work well with the design.


----------



## sachu

Thanks...yeah got those feet from Justin over at headamp. I used them on my EHHA build as well. Most excellent and a steal for the price. Brian, I would need to get one of the normal bias lambdas on loan and test them out before I invest in a pair.


----------



## gilency

The power entry I have is to be used with a 250 V fuse. Is that OK?
   
  http://parts.digikey.sg/1/1/786132-mod-pwr-entry-fuse-hldr-10a-pnl-4304-6090.html 
   
  I also want to connect  a Bulging switch to it: http://www.mouser.com/ProductDetail/Bulgin/MP0045-1E2GN012/?qs=sGAEpiMZZMvxtGF7dlGNplr9LVjb3l8KS%252bIz5FPAvA0%3d
   
  Any problems doing it?


----------



## gilency

Well, I have a problem: the -300V rail reads 300V and the LED turns on. The dummy load resistor gets hot. I get 410 mV after adjusting P2.
  The +300V rail reads 4 V and the LED wont turn on. The dummy load resistor stays cold. I get 360 mV after adjusting P1.
  The voltage from the transformers reads 250 on both.
  Why is the high rail not working?
  The instructions for testing the rails state to use the dummy resistors in parallel only for the negative rail, and only the 10K/25W for the positive rail. That's what I did.


----------



## sachu

hmm sucks..
   
  well disconnect it first, double check to see all solder joints are goood on the positive rail side. 
   
  Check to see if the components are in the right places against the BOM and the schematic. I am assuming at this point that none of the magic blue smoke has been released. 
   
  Then bring up the PSU agian with the dummy loads on both rails and see what you measure on the positve rail.


----------



## gilency

The positive rail measures 47 volts only. The negative rail measures 300.
  I had one diode backwards on the positive side, everything else looks OK. I will try again tomorrow.
  I am using MTP2P50EG instead of FQPF3P50 at Q3 and the maxed power supply.
  I checked all the solder joints, they all seem fine, and no, no blue smoke, both LEDs light up now.
  Any ideas?


----------



## runeight

Which diode was backwards?


----------



## runeight

Also, what's the voltage from T1 and T3 to ground?


----------



## gilency

Diods Z10 and Z11
  I'll measure T1 and T3 to ground right now


----------



## gilency

T1 to ground: 332V
  T3 to ground: 326V
  High rail: 48V
  Low rail: 291V
  T1-T2: 360mV. It drifts down slowly a few mV.
  T3-T4: 410.
  For what is worth, the LED in the high rail looks a little brighter than the low rail.
  I changed R15 because it was reading 1.5 instead of 475 ohms. The replacement measured 475 before I soldered it, now reads 1.5 ohms again. why?


----------



## runeight

Measure from the cathode of Z9 to ground.


----------



## gilency

Z9 to ground = 54V
  Z14 to ground=203V


----------



## runeight

First guess is that the z9,z10,z11 string has blown zeners. Try replacing all of them.


----------



## gilency

I replaced Z9, Z10 and Z11.
  Still get 48V in the high rail.
  All other measurements (low rail,T1 to ground, T3 to ground) are fine.
  z9 to ground is 45v.
  z14 to ground is 198v


----------



## runeight

The 198V makes perfect sense given where you are measuring it.
   
  We're going to have to replace components one at a time. If you are sure that the zeners are working then the next step is to replace Q9 and Q10.  I don't think that Q5 and Q6 would have been damaged by the two backward zeners, but Q9 might have been and it's just safer to swap out Q10 while you're at it.
   
  The mosfet should be ok providing that its protection diode Z1 has the correct orientation.


----------



## runeight

While you're at it, what is the voltage from Z3 to ground?


----------



## runeight

gilency, how are you doing?


----------



## gilency

Fine, just need to order some parts. Unfortunately it will take a few days for them to ship and I get a few days and have to get back to work. I will let you know when I am able to work on it again.


----------



## gilency

Can somebody point me towards a specific 4PDT switch in Mouser? Thanks


----------



## BoilermakerFan

Quote: 





gilency said:


> Can somebody point me towards a specific 4PDT switch in Mouser? Thanks


 

 For the inputs it can be a simple On-On switch:
   
  http://www.mouser.com/ProductDetail/Mountain-Switch/10TC290/?qs=sGAEpiMZZMvudeGI7i40XMiFOdVKce2XfPMzx0bS%252bxY%3d
   
  But, for a few bucks more you can have one of tthe best 4PDT, a TOCOS, from Michael Percy Audio.


----------



## gilency

OK. Thanks.I am itching to start working on my PS but waiting for parts. 
  One more question, How do I wire a loop out? I want to have balanced and SE in with a switch, but would like to have an RCA loop out.


----------



## spritzer

You parallel connect the RCA sockets so center pin to center pin to the switch.  With a 4PDT switch you are using common ground so don't worry about that, just connect them all together.


----------



## gilency

Thank you Spritzer.


----------



## ujamerstand

Finally able to case up my exstata hybrid:
   

   

   

   
  This one uses toshiba 2SJ74BL as input jfets, 2sc3676s as output devices. Special thanks to BoilermakerFan for making the parts suggestions!


----------



## sachu

very nice Yun!!


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> This one uses toshiba 2SJ74BL as input jfets, 2sc3676s as output devices. Special thanks to BoilermakerFan for making the parts suggestions!


 


  Your welcome, but I can't take credit for the 2SC3676s, mine came from pabbi1 and he received the recommendation or confirmation the substitution would work from luvdunhill and probably others.  I just like the 74BLs over all other small signal transistors, so I have a nice stash of them for all of my Cavalli and Pass builds. 
   
  I'm just glad you decided to go through with the build and are enjoying it.


----------



## ujamerstand

A stash of 74BLs? You lucky person! 
	

	
	
		
		

		
			





 I recently bought a bunch off ebay, I suspect that they are fakes, but for the price along with buyer's protection I couldn't resist. I'll have to take them to the ece lab to do some testing once they arrive...


----------



## pabbi1

2sc3676 are easy to recommend when you have a bunch in the parts box...  -)
   
  So, it's pretty and all, but how does it sound?


----------



## ujamerstand

I'll tell you that it sounds very good to my ears.  But honestly I don't have any other electrostatic amplifiers to it compare to. I have heard the T2 before, but that was during a meet, and I spent too little time on it to be able know the difference.


----------



## gilency

Can these (Cornell 5989-630V0.1-F):
_http://www.mouser.com/ProductDetail/Cornell-Dubilier/DME6P1K-F/?qs=sGAEpiMZZMvOcEq4GH1AApI0TQn9XbqdZEhD3ZtjwwM%3d_
   
  be used instead of these (Wima 505-MKS4.1/630/10) on C5,C7?
_http://www.mouser.com/ProductDetail/WIMA/MKS4-1-630-10/?qs=sGAEpiMZZMvOcEq4GH1AAhexF5Ptk22/AogD0VKT928%3d_
  What worries me is the load life of 1000 hours on the Cornell. Does not sound like much when compared with the Wima's.
   
  On second thought, these ones I think should work I think. Am I correct?
http://www.mouser.com/ProductDetail/WIMA/MKP4-1-630-10/?qs=sGAEpiMZZMukHu%252bjC5l7YeioJxFs256siSVBMhVrtjk%3d


   
  The MKS4-.1/630/10 is out of stock.
   
  BTW, still waiting for parts.


----------



## HiGHFLYiN9

Very nice work Ujamerstand! I'm using the same Par Metal Case for my build


----------



## HeadphoneAddict

I've gotten my eXStatA back from Sachu after having the digital attenuator repaired, and loving it with my SR-Lambda tonight. Unfortunately I think I killed my hybrid eXStatA PSU by running it without a proper load on the PSU because the wires between PSU and amp boards were loose. That's why the PSU LED would alternately go on and off for a while. Fortunately I've got a new PSU board and parts to stuff it coming soon.


----------



## sachu

nice..glad you got it back safely and everything is well with the world again..well apart from me having to debug the failed PSU. Should have it fixed this weekend hopefully.


----------



## gilency

Gentlemen:
  Success powering the PS!
  T1-T2: 360 mV
  T3-T4: 410 mV
  Both rails: about 315 V
  T1 and T3 with respect to ground: approx 331 V each.


----------



## runeight

gilency, I replied to a PM, but I see that you are past that now. Glad you got this far.


----------



## Music Daedalus

Hi, just wondering, How can I get the PCB for the ss version of exstata now...
   
   
  I tried to do some search but comes up with nothing


----------



## sachu

post a wanted ad..and hit up people who bought boards in the group buy but haven't yet posted any thing aboiut their builds..meaning they are sitting on their backsides doing nothing with it..or don't know how to sniff solder.


----------



## gilency

Thank you Alex. I am happy I have come this far. And messing up the PS was the best thing it could have happened. I learned a lot.
  I already started working on the enclosure (Lansing B style 16.73 x 12.00 x 3.47 inches), but need to finish wiring the amplifier.
  I am afraid I wont be able to do much for the month of december due to an extremely busy work schedule, but will try here and there.


----------



## gilency

Pardon the mess.
  Here is where I am at now. Testing amplifier tomorrow.


----------



## pabbi1

You are so almost there... it will be really interesting for you to compare the two amps.


----------



## gilency

...


----------



## gilency

..


----------



## paxeaxe23

I find myself in the position that I can't build my Hybrid and don't really see a time soon when I will be able to.
   
  Therefore I am offering my Boards and components (including Hammond Transformer and 2 Stax connectors, but no case and no Pot)
   
  I live in Germany, so it would probably be easier to post within Europe if anyone outside europe is interested I would have to find out what shipping would cost.
   
  PM me for further information, and list of what I have
   
   
  Francis


----------



## pedefede

Hi All
   
  Finally had time to finish my PS and amp modules.But the PS has trouble:
  LED:  light at power on
  T1-2 can be adjusted to 360mV (and T3-4 to 410mV)
   
  +rails: 20,8V
  -rail: -19,8V
   
   
  everything seems pretty symmetrical:
  measurements:
  T1: 314V
  T3: -318V
  Z1 anode: 309V
  Z2 cathode: -309V
   
  [added 6 jan:]
   
  Z3 cathode: 20,4V
  Z8 anode: -19,3V
  R13 (1N5294): 10,8V
  R141N5294): -9,8V 
  Z9 cathode: 21 V
  Z14 anode: -20V 
   
  V across Z1: 3,99V
  V across Z1: 4,04V
   
  Anyone got an idea?


----------



## pedefede

Ok - triple-checked the components, and found the error:
  I switched the MJE340's and 350's  
   
  Dont drink while stuffing in components  ...


----------



## sachu

bummer dude..


----------



## SteveA

I just bought an Exstata from Skullguise (thanks!) and am in the process of purchasing a pair of 407s to mate with it.  Meanwhile, I would like to ensure that I have all the updates for this unit as I understand it has gone through several iterations / stages.  From the mostly crappy photo below, can anyone tell me what vintage this is and what if anything I should do to make it as good as it possbily can be?
   
   
  Thanks!
  Steve


----------



## padam

It is the prototype version (at least I think so, mine looked different), I am not sure if you can upgrade it easily.


----------



## pabbi1

That is a prototype that I built with the CCS mod, which is all but identical to the current version. Nothing you need to do - except get those phones.


----------



## SteveA

Pabbi - Thanks for the info. Yes I'm looking forward to hearing it!

Best regards,
Steve


----------



## ting.mike

Hi,
  I've assembled the PSU completely using the parts from the BOM. In initial check up, everything measures up correctly to the values that are specified on the Cavalli website. The only issue I have is setting the bias voltage. The bias voltage maxes at around 535V, and it won't go any higher (trimpots are already making clicking noise). Any idea what's wrong?
   
  I'm getting +300V and -300V rails, T1-T2 360mV, T3-T4 410mV, T1 and T3 to ground measures ~330V.
   
  I'm using the 369JX Hammon travo, which is the universal version of the 269JX.
   
  Thanks.


----------



## sachu

Quote: 





pabbi1 said:


> That is a prototype that I built with the CCS mod, which is all but identical to the current version. Nothing you need to do - except get those phones.


 


  oh right...that pic doesn't hsow the heatsinks hanging off the sides well


----------



## pabbi1

Nope, you are thinking (perhaps) of my monster power caps on my personal build... here is a better pic of that build:


----------



## pertube

[size=medium]Hi folks,[/size]
  [size=medium]Today I checked Mouser online for KSC5042 transistors it seem to be an End-of-Life-Product any suggestions for replacement? Can we take KSC5026 - a bit high output capacitance probably![/size]
  [size=medium]Thx[/size]


----------



## sachu

Use this
   
http://www.mouser.com/search/ProductDetail.aspx?qs=2V4k6Hs0nQk9VCKsIWmecw%3D%3D


----------



## ting.mike

Quote: 





ting.mike said:


> Hi,
> I've assembled the PSU completely using the parts from the BOM. In initial check up, everything measures up correctly to the values that are specified on the Cavalli website. The only issue I have is setting the bias voltage. The bias voltage maxes at around 535V, and it won't go any higher (trimpots are already making clicking noise). Any idea what's wrong?
> 
> I'm getting +300V and -300V rails, T1-T2 360mV, T3-T4 410mV, T1 and T3 to ground measures ~330V.
> ...


 
   
  Alex,
  can you help me out on this issue? Looking at the schematic of the PSU, the input from the travo is 250-0-250, then after going through the two diodes, is it possible to get the voltage to be higher than 500V on the high bias terminal?
   
  If instead I use a 300-0-300 secondary voltage on the travo (I do that by hooking up the primaries on 200V, instead of 230V), then I didn't have any problem getting up to 600V on the high bias terminal. A friend I talked to recommended changing C5 to the mylar type (I think this is what Al used on his built, looking at the pictures he posted) to help get a higher voltage.


----------



## chinsettawong

I just finished my amp this past weekend.  The amp sounds wonderful.  
   

   

   

   

   
  Wachara C.


----------



## sachu

wow..very nice compact build. Kudos!


----------



## dBel84

From your comments about sound, I am assuming that the ExStata drives your DIY stats well too. Congratulations, I think you now own the first complete DIY stat rig - headphones and amp , quite an achievement..dB


----------



## runeight

Quote: 





ting.mike said:


> Quote:
> 
> 
> 
> ...


 


 Are you measuring the voltage at the test point or at the terminal block?


----------



## ting.mike

Thanks, Alex. I measured at the testpoints, exactly as instructed on the website:
   
 Bias Supplies  Bias voltages are measured at the testpoints NOT at the terminals on the block.

 Turn on the PS.
 Measure from either test point to ground. The instant you touch the DMM to the testpoint is the correct voltage. If the DMM lead stays in contact with the testpoint it will pull the voltage down. Therefore, get the measurement at the moment you touch the testpoint.
 Adjust the associated trimpot to change the voltage, repeating the process of momentarily touching the testpoint until you have the voltage you want.
 Do the same for the other bias supply.
 Power down.
 You're ready to attach the amplifiers.


----------



## runeight

OK. Just checking the simplest thing first. Might you kindly post a close up photo of the bias section of the PS both top and bottom of board? If you have already, just send me back to the right post.


----------



## chinsettawong

Quote: 





dbel84 said:


> From your comments about sound, I am assuming that the ExStata drives your DIY stats well too. Congratulations, I think you now own the first complete DIY stat rig - headphones and amp , quite an achievement..dB


 

 Hi dBel84,
   
  Yes, eXStatA drives my DIY headphones well.
   
  This isn't my first DIY stats amp.     I've built an all tubes version of stats amp which sounds pretty good too.
   
  Wachara C.


----------



## jcx

Quote: 





sachu said:


> Use this
> 
> http://www.mouser.com/search/ProductDetail.aspx?qs=2V4k6Hs0nQk9VCKsIWmecw%3D%3D


 


 ksc5027 datasheet shows 60 pF typical Cob, and a low current hfe <20 in the graph,  I realize the Cob will go down some with the high working Vce but it really is at "game changing" levels compared to the original ksc5042 part 
   
  with that much change in output C I'd want to double the output stage current bias to be able to drive both the transistor parasitic C and headphone load
   
  Sanyo 2sc3183 has the same low hfe but much lower Cob - and is current production
   
   
  if the ksc5027 added Cob is acceptable then why not mosfet fqp2n80 (or 90, or fqpf insulated case) - similar C on the output - looks like a possible "drop in" - but needs to be checked with a fast scope to see if gate stopper R is needed for stability
   
  ixys ixtp01n100 is attractive with ~1/2 the added output parasitic C but would need a couple of LEDs in the source lead of the ccs, mirror Qs to overcome the depletion mode negative gate bias - other ixys parts are lower output C but not in TO-220 and harder to get
   
   
  plus how many will just prefer the idea of mosfet output vs bjt
   
   
  if the "project owners" want to keep the SS version alive then I think they should select/validate a better output Q replacement part


----------



## runeight

Yes, agreed. This is one of the reasons that the KSC5042 was chosen in the first place. As the project owner, I don't expect that there will be any more board runs or group buys. This particular design has served its original purpose.
   
  A good solution for anyone who can't find the KSC5042 is to use the Sanyo device.


----------



## studeb

i cannot find the 2sc3183, where should i look?


----------



## ujamerstand

bdent, mcmelectronics.


----------



## ting.mike

Sorry been busy these two days. Here it is:
   


   
  I also need to add that I'm using a 1000V version for the C5 and C7 (couldn't get the 630V version). One diode and one resistor are soldered under the board since there is no space left.


----------



## runeight

Thanks. Sorry to ask for more pics, but you take a close up of the bias section on the underside? As close as you can get with focus.
   
  The top side looks ok. If I may ask, what is the white thing that goes from one of the pads on D7 toward the resistor?


----------



## pedefede

I messed up my PSU, so I tried build a salas SSHV instead. It came alive (after some trouble with dead mosfets) last night 

Then connected the SS-amp modules.
One of them works!, and i could adjust difference in output Voltage to 0V with P2

The other one dont :mad:
Anyone has some good input?
I tried measured the voltage (with reference to ground) around the circuit:

voltage on good amp in ()
out- +285V (11)
out- -295V (11)
P2/R36 -18,9V (-1,52 on good amp)
P2/R35 -19,3V (-1,53 on good amp)
R36/Q2 -18,8V (-1,57 on good amp)
R35/Q1 -19,4V (-1,56 on good amp)
R26/R27 297 (201)
R27/R28 291 (106)
R23/R24 100 (202)
R24/R25 -91 (106)
R33/R34 130 (5,4)
R32/R31 -156 (5,0)
Q4/R6 -300 (-243)
Q3/R5 -300 (-243)
R11/R12 -160 (-160)
R6/Q7 -300 (-300)
R5/Q6 -300 (-300)

Then my child woke up from sleep ... 
I might try to check the transistors tonight ...
[[EDIT: 14/2]]
All KSC5027 (replaced 5042) measured ok on both amps (HFE around 25 in circuit)
both 1156 is hard to measure in circuit (HFE around 2 in circuit ... :confused_face: ) But the same on both amps.

Q1 and Q2 (sj74 bought on ebay, matched quad with Idss around 15,9)
- both has a drain-to-source resistance about 75ohm on good amp
- on bad amp Q2 has 75 ohm as well, but Q1 is 88 ohm. 
Is that enough to change the pair? i'd suspect a bigger deviance, if the fet was blown....

the BC550's is hard (impossible) to measure in circuit ...

Anyone got some tips??
]] 





Peter


----------



## sachu

hey Peter,
   
  Any progress?


----------



## pertube

Quote: 





runeight said:


> Yes, agreed. This is one of the reasons that the KSC5042 was chosen in the first place. As the project owner, I don't expect that there will be any more board runs or group buys. This particular design has served its original purpose.
> 
> A good solution for anyone who can't find the KSC5042 is to use the Sanyo device.


 

  
  [size=10pt]I have found a Sanyo 2SC 3676 device is TO 220 packaging, has Cob 5 pF, Hfe 30 and Vceo 900V think it is a real good replacement part - what do you think? [/size]
 [size=10pt]Hope it is still in production, can somebody advice a source for Europe especially Germany [/size]
  [size=10pt]THX[/size]
  [size=10pt]pertube[/size]


----------



## pabbi1

Well, I can speak to that. Having had (past tense) a bunch of 2sc3676, all my builds have them, and they work very well. I had mine from having used them in the Blue Hawaii, and needed a bunch...   
   
  No sourcing ideas, as mine were purchased years ago.


----------



## chinsettawong

HI,
   
  My eXStatA Hybrid is having a little 50Hz hum.  The hum is louder on the left side.  I've checked the DC offset and balance, and everything seemed fine.  What can I do to fix it?
   
  Wachara C.


----------



## FrankCooter

This design doesn't seem particularly susceptible to induced power supply hum, but you've got your power transformer pretty tight against your amp boards. If the louder left side is the board that is closest to the transformer it might be an indication some interaction is going on.  If there is interaction, extra space or perhaps physical reorientation of the transformer would be the answer. Or if you want to keep your nice tight build , try an R core or toroid.


----------



## chinsettawong

Hi FrankCooter,
   
  Yes, I thought about that too.  I will try to confirm if the hum indeed comes from the power supply.
   
  Wachara C.


----------



## chinsettawong

I just took out the power transformer and put it further away from the left channel board and the hum did really go away.  I tried to rearrange the transformer, but, unfortunately my enclosure was just too small.  I guess I just have to live with this little hum.  
   
  Wachara C.


----------



## HiGHFLYiN9

Hmmn, Perhaps you could try mounting a piece of metal between the board and the transformer that's connected to chassis ground.


----------



## cfcubed

Quote: 





chinsettawong said:


> I just took out the power transformer and put it further away from the left channel board and the hum did really go away.  I tried to rearrange the transformer, but, unfortunately my enclosure was just too small.  I guess I just have to live with this little hum.
> 
> Wachara C.


 

 I've come around to making my builds 2-case ones at this point (e.g. wallwart or DIY power brick in small headamp cases).  IIRC the only ones that are really happy w/transformers in their cases are using (expensive) potted toroids, or others as Frank suggested.  Might not be feasible/desirable for this project or this build but I've taken to putting the transformers in their own cheap case (fused, etc) that can sit on the floor w/multiple-conductor output wire + DIN connectors & such depending on load.  This is a HV project, so it'd be trickier & more expensive I guess.
   
  From what I've read & from playing around with metal shielding plates is that they may help but electromagnetic fields are stubborn.  I've had some success rotating transformers but distance (e.g. 6"+) is your friend.


----------



## jcx

iron (low carbon steel) is a cheap magnetic conductor - but there is no "magnetic gnd"  you have to think in terms of spatially "shorting out" the field
   
   
  you also have to avoid creating a hazard with electrical shorting to the added metal or causing over heating with a closed box - perforated heavy gage low carbon steel was used in the classic Lambda linear supplies
   
   
  sometimes twisting (the right pairs), moving signal wiring relative to power can help - as does twisting power wiring to minimize magnetic field radiating loop area


----------



## holland

Why not just modify it to use 2 cases?  You can connect the chassis/earth with an earth wire strapping the 2 chassis together.  In that way, you've more or less built a faraday cage for the transformer.  Use the appropriate connectors for the power feeding into the amp section.  It'll be more expensive, but I wouldn't live with a hum like that.  You can keep the PSU in the amp case, but move the transformer out.
   
  A piece of iron shielding the transformer may help, but it looks too tight in your chassis to really attach it anywhere.  You can try bisecting your case between the power and amp boards, but try not to short anything out.
   
  Use an isolation transformer with a fuse, and fuse your circuit, just in case things do short out.


----------



## jcx

chinsettawong,
   
  now I see the pics, - reroute wiring! - "best" would be put inputs on front panel (output too usually but at esl V levels, balanced output it won't make any hum difference)
   
  looks you can't get to far from the xmfr but get signal wires as far away as possible - more uniform mag field at a distance mean twisted pairs (even coax) work better at rejecting hum
   
  you also want to stay away from ps rectifier current loops which give "buzz"  - this probably means running input wire signal/gnd pairs along top edge of case on the side away from the xfmr
   
  heater wiring doesn't look like tightly twisted pairs - these carry the highest line frequency current in the box and should be twisted in +/- pairs (for each heater) to cut radiating loop area to the min
   
  pwr entry wiring to any sw, fuse, iec to xfmr should all be twisted pairs of line/neutral or hot/switched -  any current loop should be made small by twisting the wires and their "returns" and they should be moved as far from the signal wires as possible
   
   
  but the biggest improvement should be expected from properly using the balanced input on each amp board
   
  it looks like you're not taking advantage of the amp board's differential inputs, the minus input shouldn't be jumpered to board gnd - it should be the signal gnd from the RCA input - the (tightly twisted pair, 3-wire flat cable gnd-sig-gnd, star quad or gnd shield of RCA/coax) signal gnd wires for each channel should be carried from the input connector to the pot and from the pot gnd to each amp minus input individually - as closely following each channel's signal wire as possible - it looks like you already have isolated the RCA from the case
   
  with RCA near the power end of the box you really want spatially "balanced" signal gnd - don't leave a asymmetric mag field sampling loop where the signal enters the case - at least bend ring washer tab closer to the RCA central axis - better still to use a couple of identical washers evenly spaced and tease out pigtails 180 degrees apart on a nice RCA coax braid (or again 3 wires in flat cable evenly spaced gnd-sig-gnd gives a type of mag field rejecting cable, star quad is great too)
   
  somewhere each signal gnd will need to connect separately to board/chassis/safety gnd with 10-100 Ohm resistors - to limit the input common mode range - but you don't want any differences between the signal and signal gnd wiring from RCA connector to the +/- input of the amp board to take advantage of the balanced input's common mode rejection ability


----------



## chinsettawong

Hi,
   
  Thanks a lot for giving me good advices.  I'll try to see what I can do and report back.  
   
  Wachara C.


----------



## pedefede

sachu said:


> hey Peter,
> 
> Any progress?




Found the problem. (With some help from Alex .. thanks!)

I changed the 2 FETs (2sj74), and it works now 

I suspect, it was Q1, that was too "open", and got all the current. I measured Idss to around 30 (!!) and a bit fluctuating - it was suppused to be matched with the other one at 15,9mA

Now i "just" need to wire, and assemble the cabinet ... 

peter


----------



## sachu

oh excellent news..congrats!!
   
  I think i might have an extra pair of JFETs lying about..will pop those in and see what comes off of it on this board i am fixing.  THe symptoms seem identical so i am hopeful replacing JFETs will cure it.


----------



## HeadphoneAddict

Quote: 





sachu said:


> oh excellent news..congrats!!
> 
> I think i might have an extra pair of JFETs lying about..will pop those in and see what comes off of it on this board i am fixing.  THe symptoms seem identical so i am hopeful replacing JFETs will cure it.


 

 Fingers crossed.


----------



## ting.mike

I have some extra quads in case anyone needs them. I have a few quads in the 10s and 11s and a decent quad in the 14s. 
   
  The Exstata is alive and is making sweet sound. I can't listen to it for too long yet, as I'm still having trouble with DC-offset and Bias settings. I used a 12.0, 12.3, 12.3, and 12.6 set of J271.
The Bias is still unnaturally low (520+V is maximum, 260-0-260 input on PSU) though surprisingly the O2 sounds quite good out of it. The DC-offset is impossible to nail down correctly. It jumps anywhere between the range of 200mV to -200mV, likewise the output to ground measurement on the amp also jumps around. Reading on the other thread, I found Alex saying that offset within 1V is okay, so I that problem is solved. 
   

_If you get offsets, at temperature, that are less than 1V that's the best that this amp will do and it is plenty good enough for headphones that thrive on hundreds of volts across their stators. And, the offsets will wander around due to various thermal fluctuations. This is normal too. _
  http://www.head-fi.org/forum/thread/447950/exstata-diy-electrostatic-amp-for-intermediate-diyers/1380#post_6205632
   
  The only problem is getting the bias voltage to reach 580V. Right now I'm wiring the primaries on 220V, and secondaries at 265-0-265 gives me a 530V max bias. I can play around with different primaries (say primary at 200V, and get 300-0-300 secondary and it'll give me a 600V max bias, but I will be stressing the travo).
   
  Here is a shot of the wiring. I took out the output and input wiring for the photograph.
   

   
  Here is a shot of the PSU underside: (The resistor and diode are put down there because I am using larger 1000V caps and have no space on the top side)

   
  And the two amplifier boards:


----------



## Alex_O Rules

Hi all!
   
  My first Exstata build.  Does anyone have any Stax connectors left?  Also, in the panel templates from Sachu, I noticed they are 106mm x 310mm.  Which enclosure does this correspond to?  I have a parmetals 20-series case that is 12" x 12" x 5".  It would seem that Sachu's FPE templates would not fit.  Also- can someone provide me with the part numbers for each panel component (i.e. XLR females, IEC input, etc) that fit in Sachu's template?  Is there a preferred potentiometer resistance for the Exstata?  Any issue if I do away with the normal bias output?
   
  Thanks so much!!!
   
  Alex_O


----------



## HeadphoneAddict

Quote: 





alex_o rules said:


> Hi all!
> 
> My first Exstata build.  Does anyone have any Stax connectors left?  Also, in the panel templates from Sachu, I noticed they are 106mm x 310mm.  Which enclosure does this correspond to?  I have a parmetals 20-series case that is 12" x 12" x 5".  It would seem that Sachu's FPE templates would not fit.  Also- can someone provide me with the part numbers for each panel component (i.e. XLR females, IEC input, etc) that fit in Sachu's template?  Is there a preferred potentiometer resistance for the Exstata?  Any issue if I do away with the normal bias output?
> 
> ...


 

 I think the 106 x 310 is the 12 inch panel (that is what 310mm is), and the 106mm is a little over 4" which is about right on my 12 x 12 x 4 par metal case.  Are you sure yours is 12 x 12 x 5?
   
  Unfortunately I don't think I have any part numbers.  I can look at my emails from Sachu though.


----------



## Sathimas

Why has it become so quiet here?
   
  Are the boards sold out ?
  Nobody else building the amp at the moment?
   
  I used mine only rarely over the last weeks since I moved to a new place
  but I'm still very happy everytime I turn it on and enjoy the sound.
   
  What are the future plans for the exstata?
  (If there are any atm, I think Alex is busy with the ehha and cth revisions and the liquid fire ...)


----------



## sachu

Quote: 





alex_o rules said:


> Hi all!
> 
> My first Exstata build.  Does anyone have any Stax connectors left?  Also, in the panel templates from Sachu, I noticed they are 106mm x 310mm.  Which enclosure does this correspond to?  I have a parmetals 20-series case that is 12" x 12" x 5".  It would seem that Sachu's FPE templates would not fit.  Also- can someone provide me with the part numbers for each panel component (i.e. XLR females, IEC input, etc) that fit in Sachu's template?  Is there a preferred potentiometer resistance for the Exstata?  Any issue if I do away with the normal bias output?
> 
> ...


 

 The files were for a 12 x 12 x 4 par metal chassis. 
  These XLR jacks should fit
   
http://www.mouser.com/ProductDetail/Neutrik/NC3FD-L-B-1/?qs=sGAEpiMZZMv0W4pxf2HiV0%252bKdhvD8lQRjG7MHFl3694%3d
   
  This IEC should work i believe
   
http://www.mouser.com/ProductDetail/Schurter/61003200/?qs=sGAEpiMZZMv1TUPJeFpwblxZ%252bgbqW48rXGwWN2q2RkE%3d
   
   
  And this should be the fuse holder i use.
   
http://www.mouser.com/ProductDetail/Eagle-Plastic-Devices/441-R314A-GRX/?qs=sGAEpiMZZMukmSYeDOiaDI%2f%2f6RnPbptRBNrw2pwyBDA%3d
   
  Double check everything though with their individual datasheets.
   
  Course, feel free to change the template to do your own thing.
  Quote: 





sathimas said:


> Why has it become so quiet here?
> 
> Are the boards sold out ?
> Nobody else building the amp at the moment?
> ...


 

 Yup. Boards are sold out.
   
  Don't believe there are any more plans for the exstata. Think it has served its purpose with  more than 150 board sets made.


----------



## Alex_O Rules

Thanks everyone!
   
  Do any changes need to made to accommodate the Cooper 78-S6S jack?  If so, can I get a hand with it?  I've never done anything with FPE, and given how expensive the panels are I don't want to mess up.


----------



## Sathimas

Quote: 





> Yup. Boards are sold out.
> Don't believe there are any more plans for the exstata. Think it has served its purpose with  more than 150 board sets made.


 
   
  Sorry to hear that - the exstata was fun to build and as far as I know the cheapest way
  to enter the stax-world - on a high level I think. But nonetheless, 150 units is much more
  than I expected.
   
  Does anybody have a clue how often the EHHA or Bijou have been built?


----------



## pabbi1

Jeff @GlassJar would most likely know, as he is the sole source of boards, AFAIK, or certainly the greatest majority of them, as there may have been some rogue boards on the EHHA (we'll let the sleeping dog lay). It is sad that the 150 eXStatA units don't testify more, and, just maybe, won't be the end of that lineage.  I still use mine on an almost daily basis.


----------



## BoilermakerFan

I know of at least 6 sets of boards that haven't been built yet.  Most due to their builders lack of time.  Seems we all became busy at once.  I've sold all of my sets off to others with two sets going to existing who previously sold off their amps then had sellers remorse so they bought new boards.  Three others went to new builders.  I've only sold off all of mine since I have the other prototype to build so I felt I should let somebody else have the open source DIY boards.


----------



## Lou Erickson

I have a set of boards from the run in late 2009, and have every intention of building them.  I believe I have all the parts as well.  I'll probably be here in a few weeks asking questions.  Just as I got the parts in, I also started classes to finish the degree I dropped out of fifteen years ago, and that consumed all my time.
   
  I'm done with that in a week.
   
  I have a couple of little warm-up projects to build - a Cmoy, a Starving Student, and an odd card for the Apple II - but then I'll dive right in to the eXStatA.
   
  I have a nabu case to put it into to get started with and may do something fancier if I am that motivated.


----------



## Alex_O Rules

Hey all.  I thought I had more time for this project, but it looks like my work life is going to attack me for a few months.  If anyone has an eXStatA (or 717 or KGSS) they are not using and wishes to sell, please drop me a PM.


----------



## gooky

I was told I should make a post here if I'm interested in commissioning an eXStata amp.  Please pm me if you are able to build one, or have parts that you would like to sell, thanks.

 Hanson


----------



## drclaw

It's been taken. Thanks!


----------



## HeadphoneAddict

Quote: 





drclaw said:


> I have had the amp board stuffed for some time now and waiting to get the parts for the ps; however, it looks as if I will not be able to for the foreseeable future.  So, I would like to pass this project on to someone else who can give it the life it deserves.  It is the tube version, and I have the amp board stuffed.  The power supply board is not, and I don't have any parts for it except a cap, I think its position is C6.  I also have 5 RCA tubes and 4 other tubes.  Also I have several connectors.  I figured it would only be fair if I charged what I paid for it all, it's not negotiable.  PM me if you have any questions, want pics, the price, etc.


 

 I have a hybrid eXStatA with a bad right channel.  I have the complete BOM to build SS amp boards to go in it, but I can't stuff them.  I would be very interested in your stuff, where I would take the built amp boards and transplant them into my broken amp (and then sell my SS boards and parts)
   
  I'll PM you now.  Thanks!


----------



## Keithpgdrb

Hey all. I am embarrassed to say that I am one of those builders who has been sitting on his exstata boards. But, having recently finished restoring a fisher 500c tube amp, I feel a bit more confident in my DIY skills, and am ready to start planning and gathering for the exstata.
   
  At this time, I have:
  -1 set of exstata hybrid boards
  -luvdunhills plugs for both normal and high bias
   
  Are there things from the BOM that i should get from members here?  I'm thinking specifically of the matched items. Tubes, jfets, etc.  
   
  I have been out of the loop for a while. We're there any tweaks to the hybrid boards that I need to be aware of?
   
  Over the next month or so, I will be reading all of the exstata threads to avoid asking questions that have been addressed already.  I will be back for help without question.   I'm very excited about finally getting it together on this. I hope to start building by January at the latest.


----------



## UKToecutter

Hi
   
  If anybody has a board set (SS or Hybrid) that they would like to sell, a PM would be appreciated.
   
  Many Thanks
   
  Andy


----------



## loserica

Hi,
  This is my amplifier. It's the "SS" version. I am very pleased the sound!


----------



## sachu

Quote: 





keithpgdrb said:


> Hey all. I am embarrassed to say that I am one of those builders who has been sitting on his exstata boards. But, having recently finished restoring a fisher 500c tube amp, I feel a bit more confident in my DIY skills, and am ready to start planning and gathering for the exstata.
> 
> At this time, I have:
> -1 set of exstata hybrid boards
> ...


 


   I might have some parts that you could use and taht i need to get rid of. Let me know and its yours. 
   
   
  Quote: 





loserica said:


> Hi,
> This is my amplifier. It's the "SS" version. I am very pleased the sound!


 


  Nicely done!!!


----------



## Keithpgdrb

geez, would you believe I just found this.  pm incoming.
  Quote: 





sachu said:


> I might have some parts that you could use and taht i need to get rid of. Let me know and its yours.
> 
> 
> 
> ...


----------



## Keithpgdrb

not much action here anymore.  I must be the last one who hasnt built his amp yet.  how humiliating.


----------



## Lou Erickson

I haven't built mine either.  I keep thinking, "Sometime when I'm not so busy" and that never happens.
   
  Last time I checked, I had all the parts.


----------



## AmarokCZ

Before I built my own electrostatic amp I improved eXStatA ... I increased Iq (which was originally quite low), but (for me) with no significant step forward. For me EXStatA is just badly designed amp, because I'm a fan of low distortion amps.
  If you are looking for more accurate amp try another one. If you are (as I call it) "distortion lover" try higher Iq.


----------



## Keithpgdrb

​


amarokcz said:


> Before I built my own electrostatic amp I improved eXStatA ... I increased Iq (which was originally quite low), but (for me) with no significant step forward. For me EXStatA is just badly designed amp, because I'm a fan of low distortion amps.
> If you are looking for more accurate amp try another one. If you are (as I call it) "distortion lover" try higher Iq.




What?


----------



## Sathimas

Is there any link or proof to that measurements?


----------



## AmarokCZ

*Keithpgdrb: *you maybe misunderstood me, I am not saying that eXStatA is bad in general. It's just bad for me, because I prefer low distortion, neutral sound,... Many other people like amplifiers that intentionally adds distortion, so from their point of view it's great amp!
*marcus1:* those numbers are roughly similar to my measurements.


----------



## Beefy

Quote: 





sathimas said:


> Is there any link or proof to that measurements?


 

 Yeah, the evidence can be found if you know where to look. The Exstata pushes some pretty high distortion at even 100V P-P. Still sounds great with the Lambda to my ears.


----------



## Sathimas

Quote: 





> Yeah, the evidence can be found if you know where to look


 
   
  Well, this is worse than no answer ...
   
   
  I just saw that kevin gilmore himself showed these values, so I think it's reliable.
   
  As far as I could see the "improvements" mentioned where never concretely discussed?


----------



## Beefy

Quote: 





> Originally Posted by *Sathimas* /img/forum/go_quote.gif
> 
> I just saw that kevin gilmore himself showed these values, so I think it's reliable.
> 
> As far as I could see the "improvements" mentioned where never concretely discussed?


 

 Well, by the time you tack on all the extra bits required to bring the distortion down, you lose all the benefits the Exstata had anyway - low power usage, small footprint, etc. So why jazz up the Exstata when you can just start with a more robust base design?


----------



## spritzer

As with so much of the stuff we do, Kevin and I don't spend a lot of time discussing it in public.  Boards for the improved version were ordered and the improvements are nothing short of drastic, bringing the sound much closer in quality to the KGSSHV.  Here is a (rather large) picture of the populated boards:
   
  http://img833.imageshack.us/img833/4126/exstatav2.jpg
   
  As it happens they are sitting on my desk now since I finally got a chassis for them and the PSU.  I will use most of the same parts as in my other Exstata so I can easily compare the two.  This build used 2SA4686A's and 2SA1831's for the CCS (I ran out of 2SA1968's). 
   
  Granted the boards are larger than what Alex drew up but that's just because I had the KGSSHV layout and modified it to fit plus I decreased the board size a bit.  In reality this version is just a little bit more expensive to build while being much superior in every way.  Far higher voltage swing with +/-400V rails, more standing power for the output stage and distortion a few orders of magnitude lower.  We won't make any more of these boards though since we have a new "poor mans" ready for testing.  Same power supply as the KGSSHV but all tube, balanced from input through to output.


----------



## Sathimas

Quote: 





> We won't make any more of these boards though* since we have a new "poor mans" ready for testing.*


 
   
  Sounds interesting 
   
  Not that I have time or money for another electrostatic amp at the moment (building an EHHA)
  but nonetheless I'd like to stay informed - is there any website where I can find more information?
   
  By the way - those distortion measurements - were they done with the hybrid or the SS version?
  I know next to nothing about the circuits or whatever devides a good one from a bad one - so please
  excuse my naive questions.
   
   
  Quote: 





> So why jazz up the Exstata when you can just start with a more robust base design?


 
   
  It sounded like with small improvements (e.g. changing few parts) a much better performance could be achieved.
  (And I don't have _that _much money to spend on audio gear, at least not at the present time.)
   
  If that's not the case, I'll just live him as he is and enjoy the sound since it (with Lambda Pro) still sounds better to me than
  for example a HD800 / Lehmann BCL  or AMB M³ combo did.


----------



## spritzer

Quote: 





sathimas said:


> By the way - those distortion measurements - were they done with the hybrid or the SS version?
> I know next to nothing about the circuits or whatever devides a good one from a bad one - so please
> excuse my naive questions.


 

  Both versions were tested, the tube version tested slightly better but we focused on improving the SS version as I never saw the point with the hybrid.  Same improvements can be done to that as well.


----------



## Keithpgdrb

I have the exstata hybrid boards here, unbuilt.  is there a link to where the improvements are documented.. meaning what parts are changed out, and the improvements?  Or would it be better to wait to build the new poor mans amp, whatever that is.  I dont think I want to build more than one amp for my stats, so I have to make it count.


----------



## spritzer

Sorry about that, not enough sleep for months now...  
	

	
	
		
		

		
			




   
  You could never fit the updates to the circuit on those PCB's unless you get very creative with the chassis you put it in (i.e. for extra heat handling).  It also needs a new PSU for the higher rail voltages. 
   
  I would build them all but then again I'm a compulsive amp hoarder.


----------



## Keithpgdrb

spritzer said:


> Sorry about that, not enough sleep for months now...
> 
> 
> 
> ...




Hmm. I was getting ready to start this project. Maybe I will put it on hold till more information comes up on the poor mans amp. I generally only watch head fi. And there isn't much on any exstata problems. I had no idea improvements were being made. I'll do some more research before I proceed with anything.


----------



## marcus1

With the new "poor man's amp", any idea what the distortion measurements are as yet - better than the exstata?
   
  thanks
  
  Quote: 





spritzer said:


> Both versions were tested, the tube version tested slightly better but we focused on improving the SS version as I never saw the point with the hybrid.  Same improvements can be done to that as well.


----------



## AmarokCZ

He wrote _"...and distortion a few orders of magnitude lower." _so the distortion will be surely lower. Even my electrostatic design (see signature) has lower distortion (0.05% @ 450Vrms/1kHz) which is quite something considering its simplicity.


----------



## Forte

Quote: 





amarokcz said:


> He wrote _"...and distortion a few orders of magnitude lower." _so the distortion will be surely lower. Even my electrostatic design (see signature) has lower distortion (0.05% @ 450Vrms/1kHz) which is quite something considering its simplicity.


 


  Mind sharing how you made the DIY Stax sockets?


----------



## AmarokCZ

Basically it is: 2x 3pin XLR sockets => disassemble to get 6 pins and one jack body => make 2x round PCB with six (or five for PRO jack) holes (one PCB inside of jack; second larger PCB for connecting wires) => solder all together and isolate body from PCBs and pins with thick plastic foil and isolating paint (or just any paint) = brand new "STAX Jack"


----------



## Lou Erickson

It's the "make 2x round boards" that's the hard part, to get the layout right.
   
  Way back in 2010, luvdunhill made some Stax jacks out of teflon which he cut on a CNC machine.  I know he wasn't interested in making more, as it was a hassle, but I wonder if he'd share the files for the jacks.  I have a set and they are nice.


----------



## AmarokCZ

lou erickson said:


> It's the "make 2x round boards" that's the hard part, to get the layout right.


 
   
  It wasn't hard for me - I had two original jacks and one headphone plug, so I just copied it.
  I made holes in PCB according to this pic a it fits my SR-3 very well...

   
  BTW ... radius 9 is just radius of old Stax Jack, those two PCBs are bigger (first ~R10, second ~R15)


----------



## spritzer

The Stax jack design Kevin did for the T2DIY (milled piece of solid teflon) has been circulated so anybody with a CNC machine can make them.  The pins are available on ebay. 
  
  Quote: 





marcus1 said:


> With the new "poor man's amp", any idea what the distortion measurements are as yet - better than the exstata?
> 
> thanks


 

 Orders of magnitude referred to the Exstata V2 no amp we'll release will have a distortion figure of 1%+.  The BATE is indeed a bit of a compromise as my goal was an amp that anybody could build.  That means a bog standard tube amp which could have been built easily in the 50's so no SS parts in the amp section.  No CCS anywhere, no LED's to set the current through the tubes or any such modern stuff.  Just resistors used for everything and, yes there are a bunch of interstage coupling caps but no output caps.  This means it will never reach the vanishingly low distortion figure of the KGSSHV but more than good enough.


----------



## kevin gilmore

This is known to be exactly correct, and matches the original specification for the plug.
  I made something like 75 of them. Maybe more. All gone now.
http://gilmore.chem.northwestern.edu/staxout3.pdf


----------



## jaycalgary

If anyone wants boards for the SS build at cost pm me.


----------



## dude_500

Does anyone have boards for a hybrid + PSU build? Interested in buying if so, not sure when the next group buy will be.


----------



## cat6man

contact me via IM


----------



## HeadphoneAddict

One of these days I'll get my stuffed hybrid boards installed in my case.  After that then I'll have an SS amp board set and full BOM of parts for the amp section for sale (but I think the PSU board was used to fix my old amp - I have to check).  If the hybrid boards don't work then EVERYTHING might have to go, since I can't build the SS amp.


----------



## Sathimas

It's been too quiet arround here for too long 
   
   
  My exstata is making trouble since yesterday.
   
  I took out the boards to change some of the input wiring in the case.
  (Source selector and loop out stuff)
   
  I also cleaned the boards softly with a soft paint brush to remove some dust.
   
  The I installed everything back and began with the initial check.
   
   
  Power supply is ok - but the two boards are showing high offset values!
  Everything worked perfectly before, now I'm unable to get the voltages
  down close to 0V before the end of the trimpots is reached.
   
  One board is showing ~40V between + and -, the other one
  shows more than 150V and rising (I switched off then).
   
   
  So what the H*** is going on here?
  I can't imagine having destroyed something with a paint-brush!


----------



## Sathimas

*push*
   
  I'll dismount the boards again today and clean them with some isopropanol.
   
  Maybe that helps.


----------



## Sathimas

We'll  -fixed it 
   
  One board defenitely had a problem - maybe due to dirt or whatever.
   
  The other part of problem was me!
  I mixed up the two trimpots - so this could not work.
   
   
  Now it's sitting here at my desk, warming up and the voltages are ok.
   
   
  Now let's hope I have not mixed up L / R channels somewhere im my wiring :-D


----------



## bidoux

I took my solid state exstata out to do some measurements and now I am a bit worried about what I saw. I have been using a function generator which has a bigger output voltage swing than the ipod I usually use (around 1V for one, 2,5V for the other). At full output (which was something like 40 or 50V peak to peak) the red diodes in the power supply aren't lit as they should ; One goes blank while the other oscillates.

 So here are my two questions. How normal is it for the diodes in the power supply to act this way ? And secondly, how come the amp starts to behave  weirdly at only 50V peak to peak ? Have other builders experienced this (should I question my own building skills ? ) ?
   
  (I might to have to check again, but I really think it is 50V peak to peak. Coming from a ±300V powered amp it seems a bit low. Should the exstata be powered with something like a 10V source ? )


----------



## Beefy

From memory, those LEDs light up when current is running through the shunt regs. So I wonder whether as the output voltage goes up, current consumption increases, and your PSU is dropping out of regulation.

If this is the case, increasing the current through the first stage of the PSU by a small amount might help.


----------



## bidoux

Thank you Beefy. So toying with P1 and P2 in the power supply it is 
	

	
	
		
		

		
			





 I hope it is going to be tough enough to handle it.
   
  Edit : I checked T1-T2 and T3-T4 in the power supply. It is in the range Alex Cavalli suggested. Another thing, I plugged the eXstata into my otl tube amp to have moar input voltage (up to 6VAC) so that the output delivers around 600vac max. The red diodes in the power supply are not oscillating as I described before. I have not a clue of what is going on ... maybe the fact of the function generator being a monochromatic source plays a role ?
   
  edit2 :  I am pretty sure I wasn't careful enough with ground sharing.I probably shorcut one of the output while measuring with the oscilloscope which lead to stupid results ... I will have to try again to make sure it was indeed my own stupidity ...


----------



## Sathimas

My exstata is showing some strange behavior this evening.
   
  I have a kind of humming/buzzing sound, changing in toneheigt over time.
  It disappears are becomes at least almost unhearable when I touch
  the case or the metal parts of the cinch connectors.
   
  It's only the right channel.
   
  What might that be?


----------



## Sathimas

Push


----------



## holland

Either the case is not grounded or you've got a ground loop.


----------



## funch

Does anyone here have the 'phone jack pinout diagram used for this amp? I checked the wiki, but the pix there contradict themselves. I'm finishing up the build of
  an eXStaTa for a friend, and don't want to wreck his 950's. Thanks.


----------



## sachu

Fairly straight forward buddy.
   
http://wiki.faust3d.com/wiki/index.php?title=ImageinOut_ESP950.jpg
   
   
http://wiki.faust3d.com/wiki/index.php?title=Image:Stax_Headphone_Cable_Connectors.jpg


----------



## funch

Thanks sachu. I just traced the wiring on the 'phones (ESP 950's), and found that the amp jack diagram in the second link has the L- and R- reversed.
  Pin 4 should be R-, pin 5 L-. That's what had me baffled. I had to use a very small needle to pierce the cable so I could verifiy that they were switched
  on the diagram.


----------



## funch

I just found out that the lower part of the cable is an adapter. It seems, then, that two of the wires were switched. Mystery solved. Thanks again Sachu.


----------



## funch

This is a weird one. Maybe. I fired up the amp with the top off, turned on some tunes, and everthing was sounding great. Then I reached my left hand in to touch
  the PS heat sinks and zappo! Turns out that the exposed metal can portion of the negative rail filter cap is at -315V. Would that indicate that the cap is
  somehow shorted internally. I removed it, and all seems normal. Any thoughts?
   
  BTW, no problem with the positive rail cap.


----------



## dude_500

Quote: 





funch said:


> This is a weird one. Maybe. I fired up the amp with the top off, turned on some tunes, and everthing was sounding great. Then I reached my left hand in to touch
> the PS heat sinks and zappo! Turns out that the exposed metal can portion of the negative rail filter cap is at -315V. Would that indicate that the cap is
> somehow shorted internally. I removed it, and all seems normal. Any thoughts?
> 
> BTW, no problem with the positive rail cap.


 
   
  Capacitor cans are always somewhat hot, and you can definitely get shocked by them. They end up floating somewhere between the two poles of the cap, but they actually have some energy to them (in fact the can of a cap can pass limited DC to at least one of the terminals, I forget which)
   
  If you want some laughs, google "captret free energy" where people invented a three-terminal component called a captret, which is an electrolytic capacitor with the can as the third terminal. They claim you can extract infinite free energy from the tret terminal.


----------



## sachu

Quote: 





funch said:


> This is a weird one. Maybe. I fired up the amp with the top off, turned on some tunes, and everthing was sounding great. Then I reached my left hand in to touch
> the PS heat sinks and zappo! Turns out that the exposed metal can portion of the negative rail filter cap is at -315V. Would that indicate that the cap is
> somehow shorted internally. I removed it, and all seems normal. Any thoughts?
> 
> BTW, no problem with the positive rail cap.


 
  yeah.. i always tape up the top of the rail caps with insulation tape just for this reason..especially so on HV builds before even firing them up to test.
   
  You should be reading over -300V on the negative rail caps. This is normal and fine. seems like you are good to go. If its working, don't mess with it. Have a listen and enjoy the tunes brotha


----------



## Beefy

Quote: 





funch said:


> This is a weird one. Maybe. I fired up the amp with the top off, turned on some tunes, and everthing was sounding great. Then I reached my left hand in to touch
> the PS heat sinks and zappo! Turns out that the exposed metal can portion of the negative rail filter cap is at -315V. Would that indicate that the cap is
> somehow shorted internally. I removed it, and all seems normal. Any thoughts?


 
   
  Not sure what dude_500 is saying, because the can of the cap is connected directly to the negative terminal. On a single rail power supply this naturally sits at ground and there is no problem. On a dual rail power supply it sits at the negative voltage below ground, which is a problem.
   
  Life lessons well learned, eh?


----------



## duncan1

Just like to add in 20s/30s/40s/50s tube  radios many smoothing/reservoir  caps were like that NEG attached  to cap case . Also came across them in Tex    tube scopes I used to repair. Some had insulators     stopping the case contacting the chassis . Still have some spare ones.Split rail is mainly a newer invention[although there are some specialized usually government equipment that is older]  .allowing removal of the output cap in an amp and larger voltage swing at the output. Multiple capacitors in the one case were popular to save money. Many went faulty[interaction].  Do not  use those types  in audio.


----------



## dude_500

Quote: 





beefy said:


> Not sure what dude_500 is saying, because the can of the cap is connected directly to the negative terminal. On a single rail power supply this naturally sits at ground and there is no problem. On a dual rail power supply it sits at the negative voltage below ground, which is a problem.
> 
> Life lessons well learned, eh?


 
   
  Interesting, I've tested quite a few caps and never found one that was electrically connected to the negative terminal. You can do cool stuff with the case like connecting it in a certain configuration with all three terminals to make a dead 9V battery have a higher voltage the next day (no I don't claim it's free energy, some chemical reaction probably but still interesting none the less).


----------



## duncan1

The old caps  had cases that that WERE connected to the negative. I hold in my hand as I type one taken from  a 50s UK tube  radio I repaired  25yrs ago. =HUNTS-capacitors[well known UK  capacitor company] cap-1-32UF-275V-DC --2-16UF--275V-DC -3-25UF-25V--max ripple=250MA---CAN NEGATIVE. I have 100s of them !! You want the makers serial no?=KDQ 854G -    THH -.The casing of ALL those  types of caps have soldering tags ALL round them for the NEGATIVE connection and ALL are CASING NEGATIVE. Things arent different in the US I also have many US caps with identical working connections.Yes the same isnt done in modern times but I was hard  put to find a cap relating to those eras without saying -casing negative.


----------



## funch

Thanks to all who responded.
   
  After I posted the question, I got curious and did some research and discovered that the can is in fact connected to the negative
  rail. I went one better than sachu and painted the top of the cap. This amp is sort of a second-hand commission. The original builder backed out on the owner
  who is local, so he asked me if I would build it. This the first build I've done with a hi-voltage dual supply, so the hot cap kinda' surprised me.


----------



## Beefy

Quote: 





funch said:


> so the hot cap kinda' surprised me.


 
   
  Huh, that is a very diplomatic way of describing the cursing that follows a 300V+ electric shock.


----------



## funch

That's when you know that it really hurt; when you can't even curse.


----------



## ChrisCaubin

Hey Guys,
 Sorry if I'm resurrecting an old thread. I have my first three DIY projects on their way. I would like to build this someday, but have read that this should only be attempted by someone who has a reasonable amount of experience in DIY audio. Could anybody recommend some sources that I could use (esp. video tutorials) to help me get better at this, so I can do it in around 6 months time, maybe less? I need to get better at everything, from soldering to reading schematics. 
 Thanks,
 Chris


----------



## loserica

Hey Guys,
 I sold my eXStatA in USA. To me (in Europe) it worked without problems, but in USA he can only hear some "static noise" when he plug in the Stax headphone and there is no sound. I know, eXStatA* it can be set to any voltage* (including 220V).
 Can you give us a suggestion in this regard? how to set the whole thing?
  

  
  
 Thank you!!


----------



## UKToecutter

Hi Loserica,
  
 I guess you wired the transformer for 220V like below?
  

  
 For 110V I believe it should be wired as below
  

  
 Please pitch in somebody if I'm wrong.
  
 Cheers


----------



## funch

Here is the wiring diagram.  Scroll down to 'Wiring Table' and study the 120VAC diagram.    http://www.hammondmfg.com/300series.htm
  
 Separate the Brown and Black/Red wires. Tape the ends for safety.
  
 Disconnect the Blue/Yellow wire from the power inlet. Tape the end for safety.
  
 Connect the Blue and Black wires together, then connect the pair to the Line connection on the power inlet.
  
 Disconnect the White wire from the power inlet and cut off the connector.
  
 Connect the White and Brown wires together, then connect the pair to the Neutral connection on the power inlet.


----------



## nonamodnar

So I'm the one who was fortunate to get this unit from loserica. As of now, I haven't touched the internal wiring of the amp yet. The amp is now functional with the SR-404LE despite not being rewired for 120v. Is there something I should worry about, as far as safety and performance go?


----------



## loserica

nonamodnar said:


> So I'm the one who was fortunate to get this unit from loserica. As of now, I haven't touched the internal wiring of the amp yet. The amp is now functional with the SR-404LE despite not being rewired for 120v. Is there something I should worry about, as far as safety and performance go?


 
 I think it is VERY important to set the proper voltage!! There is a risk of burn something using the 220V setting, instead of 110V!? Personal, I wouldn't risk using an improper voltage, I don't think it is safe. 
	

	
	
		
		

		
			




 We waiting for other opinions. Thank you.


----------



## UKToecutter

Sorry for my diagram.
 I thought the US was on 110V.


----------



## nonamodnar

funch said:


> Here is the wiring diagram.  Scroll down to 'Wiring Table' and study the 120VAC diagram.    http://www.hammondmfg.com/300series.htm
> 
> Separate the Brown and Black/Red wires. Tape the ends for safety.
> 
> ...


 

 Thanks funch. I changed the wiring with minimal issues. The amp is now functional at 120v.


----------



## nonamodnar

So I have been having a minor issue with the eXStatA and SR-404LE system and I hope I can find an answer here (I'm still new to the e-stat world).
 I normally have the source and the SR-404LE plugged prior to powering on. When I turn the switch, I hear a moderate screeching (more on the left driver) for 3-5 seconds before it dies down. I can hear music throughout the whole process. I'm wondering if it's an issue of my rewiring or my power condition. I'll take a picture and upload it when I get off work today.
 When I searched eXStatA build thread in the past, there was one mention of the screeching issues but it doesn't seem like the origional poster posted an update.
 Thanks a million.


----------



## funch

Just sounds like the tubes powering up. You might try leaving the 'phones unplugged until the tubes have warmed up.


----------



## nonamodnar

My eXStatA is a solid state built though.


----------



## funch

Ah, I stand corrected. Still, try leaving the 'phones unplugged for a bit after turn on, until things stabilize.


----------



## nonamodnar

I see. And by stabilize, do you mean for the amp to finish warming up?
 I tried it that way today and there was no screeching but then I had some static from plugging in the earspeakers. I guess I can't win it all.


----------



## funch

Static indicates dirty or slightly oxidized contacts. Use some contact cleaner very sparingly and see if that helps.


----------



## nonamodnar

Thanks funch, I'll try it and report back after work.


----------



## dmkbox

HI!
 Where is source of PCB for this amp?
 Or maybe pcb design?
 Interesting to build.


----------



## Sathimas

The exstata is discontinued.
  
 You will not get any boards and Mr. Cavalli will most likely not share the PCB-data.
  
 You could contact him throught his website.


----------



## funch

You could post a wanted ad in the For Sale forum.


----------



## HeadphoneAddict

dmkbox said:


> HI!
> Where is source of PCB for this amp?
> Or maybe pcb design?
> Interesting to build.


 

 I have the first hybrid eXStatA amp that wiatrob built as a prototype, but with newer boards.  It's mention in this thread, and should have pics here (dual volume controls, XLR and RCA input, normal and pro bias jacks).  
  
 The issue is that something happened to the PSU and it was rebuilt by a member here, but then the right channel went out two weeks later.  To replace the current amp boards I bought a complete set of new stuffed hybrid boards a few years ago from another forum member, but I never found the time to install them.
  
 I'd be happy to consider selling the amp as is, and all you have to do is remove the current amp boards and install the new ones.  PM me.


----------



## Sathimas

Waking the thread from the dead ...
  
 My exstata gave me a shock some days ago!
  
 I was listening to some music (moderate levels) with my Lambda Pro when
 suddenly the sound started distorting on the left channel and I got some
 deep hum too.
  
 Unplugged the phones of course and tested them on my srm xh where
 they worked properly - so the extata seems to be the problem.
  
 I ran through the setup again today and checked all the voltages and
 found nothing too alarming. Offset was about 5V on one channel, what
 does not seem to be critical (adjusted back to below 1V nonetheless).
  
 Now I'm kind of scared to plug in my phones again since I don't have
 any clue where the problem might have been.
  
  
 Any Idea?


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## crazychile

Thanks for reviving this thread. I'm an owner of an Exstata that I bought from Mjolnir Audio last year which is solid state and has an upgraded power supply. I've never been able to find out much info about it, and bought it as an upgrade for my stock Koss ESP energizer.

i was wondering how this model compares to the stock Stax amps and some of the Kevin Gilmore designs, as I'm probably going to buy L700s at some point and want to get an idea of what kind of improvement I might get with something like a KGST, etc.

Sorry to threadjack Sathimas. i'm hoping enough people see this thread again to answer both our questions.


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## Gregss

Hello,

Have been thinking of making one of these amps for a while.  Now have the time and would like to do so.  Perhaps I am missing it, but haven't found yet where I can purchase the PCB's.  Are they still available?   If not, does anyone have the gerber file so I could have some made? 

Currently have the Koss ESP950 headphones with a much better than original power supply. 

Any information would be appreciated.
Regards,
Greg


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