# Eddie Current DIY amplifier "Monolith"



## compuryan

Just saw this while browsing Eddie Current's website. Does anybody know anything about this? How long as it been out?
   
  http://www.eddiecurrent.com/Used_Stuff.html


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## nikongod

I'm curious to see a schematic, as always.


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## bala

One more curious soul!


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## nikongod

Rumors floating around the rumor mill make this sound very intriguing, particularly as a replacement for the dork-star.


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## amcananey

I was wondering the same thing. Just saw it. I've been to the EC website many times and never noticed it before...I assume it is relatively new?


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## amcananey

I like how on the website it is marked "DIY", but the URL is "Used Stuff"...


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## skeptic

Subscribed!


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## amcananey

nikongod,
   
  Where did you see the rumors you mentioned?
   
  Best regards,
  Adam


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## nikongod

Quote: 





amcananey said:


> nikongod,
> 
> Where did you see the rumors you mentioned?
> 
> ...


 
   
  A different headphone site. 
  There is not really much you can do with OPA541 (same chip as in the commercial joke) so the rumors seem to follow logic... 
   
  The option of input transformers is incredibly cool upgrade, BTW. Ignoring the cost I would much rather have this, just for that. Considering the difference in cost, its no contest.


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## amcananey

By commercial joke, I assume you are referring to what you dubbed the "dork-star"?
   
  Can you describe what input transformers do, and what their advantages are compared to coupling caps?
   
  Best,
  Adam


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## nikongod

Quote: 





amcananey said:


> By commercial joke, I assume you are referring to what you dubbed the "dork-star"?
> 
> Can you describe what input transformers do, and what their advantages are compared to coupling caps?
> 
> ...


 
   
  Yes, that is the amp. Thousands of dollars for a gainclone in a fancy box with dodgy anodizing. 
   
  Anyways, transformers are fricken awesome. They do all sorts of neat things. Some of them are similar to coupling caps, others totally pwn. 
  So on the similar things: a transformer WILL block DC from the source from hitting the amp and blowing up your junk. This is kind of a 50/50 point, because the kinds of transformers you would use here are not designed specifically to do that, but in an unusual gear failure they should save your butt. 
   
  Now, for what they do every day that is sooooooo cool. 
  Transformers make it VERY easy to make your system ground loop proof. Coupling caps don't help you here. 
   
  Transformers don't require a power supply. This is not an issue when you will be building them into something that already has a power supply for the active bits further down the chain, but you could easily build a little box to *just* convert SE to balanced (or the other way, or whatever) that sits on your desk all alone and will do its thing for 50 years or more with no intervention or complaints. 
   
  Transformers convert single ended or balanced inputs to single ended or balanced outputs. There are opamp-looking chips that do this, but they require power supplies and don't do anything for ground loops or accidents like a transformer does. 
   
  Transformers add (basically) no noise to the system. Even quiet op amps have more random noise than a nicely shielded transformer. 
   
  And finally: Although it is quite subjective there are people who just prefer the sound of transformers to the sound of caps. 
   
  Since this kind of diverged to include op amp based phase splitter chips:
  The downside of the transformer compared to those op amp thingies is that the transformers are an order of magnitude more expensive - particularly when you will be putting them into something that already has a power supply. The little op amp thingies are also likely to measure better under ideal conditions, which makes the measurements first brigade very happy, but when you get into the real world what happens is anyone's guess. Considering that the difference between 0.1%THD and 0.0001%THD is inaudible but a ground loop is not, um, yea.


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## amcananey

Cool, I appreciate the explanation. Thanks!


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## lextek

Subscribed too....


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## recstar24

+1 for input transformers. On my custom dsha1 they operate as voltage gain too, and I have a switch that can go 1:2 or 1:4. Something about noise free voltage gain is pretty special.


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## palchiu

Anyone purchased already?


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## amcananey

Anyone? Any updates? Anything?
   
  Best,
 Adam


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## CEE TEE

Thanks for reminding me...I need to order one!


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## FraGGleR

Intrigued by this as it looks like a reasonably compact way to build a balanced amp with enough power (in theory) for something like the HE-6s.  I sent a couple questions to Craig at EC.  Won't be a cheap build (not when compared to the cost of something like an Emotive X-100) as the OPA541s are about $20 a pop.  Although the build will be cheaper than a balanced B22.


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## nikongod

If you are considering building something with input transformers odds are good you have long ago placed a higher value on quality than how cheap something is.


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## spritzer

Plenty of other chips out there that are better in most aspects and cheaper too.  Just build a 4 channel gainclone and call it a day.  If you want to use a SE input, want it to be cheap and don't care about the quality you can wire up some simple DRV134 stage to do that.


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## FraGGleR

Quote: 





nikongod said:


> If you are considering building something with input transformers odds are good you have long ago placed a higher value on quality than how cheap something is.


 
   
  I very much appreciate, desire, and will pay for high quality, but I am also a cheapskate.  This is a very tough hobby for me to be in because of that   
   
  I'll focus on finishing my B22 for now.  I also have project ADD.


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## palchiu

If someone still interesting, the monolith is ready.


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## Zashoomin

I would love to know the results as well as some pictures


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## DutchGFX

Same I'd love some info


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## FraGGleR

Still tempted, but looks like it will be $300 before casework if you need the input transformers.  $200 without them.  Then again, this is similar to a $3500 amp.  Then again, that $3500 amp gets ridiculed by many.


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## DutchGFX

Quote: 





fraggler said:


> Still tempted, but looks like it will be $300 before casework if you need the input transformers.  $200 without them.  Then again, this is similar to a $3500 amp.  Then again, that $3500 amp gets ridiculed by many.


 

 May I ask what $3500 amp? lol


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## nikongod

Quote: 





dutchgfx said:


> May I ask what $3500 amp? lol


 
   
   
  The Dorkstar.


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## DutchGFX

Well does the Darkstar sound good? Lol i dont care if its ridiculed, just has to sound good


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## FraGGleR

Quote: 





dutchgfx said:


> Well does the Darkstar sound good? Lol i dont care if its ridiculed, just has to sound good


 
http://www.head-fi.org/t/565779/review-ray-samuels-audio-dark-star-solid-state-headphone-amplifier
http://www.headfonia.com/voltage-monster-ray-samuels-dark-star/


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## nikongod

Quote: 





dutchgfx said:


> Well does the Darkstar sound good? Lol i dont care if its ridiculed, just has to sound good


 
   
  The ridicule is because the Dorkstar could have been made better by a bad designer.


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## palchiu

Received
   

   
  Waiting for parts list...


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## mcluxun

Interested.
  Subscribed.


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## steel

me too


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## shipsupt

I've got one on the way as well... but I'm in the UK so shipping takes longer.  I've got no need for it, but I want to build it anyway!
   
  I've got the schematic, BOM, and instructions already.  I've asked Craig if he's OK with me posting them (out of courtesy), of course I fully expect we'll see it all up here soon.
   
  The BOM makes things super easy, essentially everything for the boards is available from Mouser except the transformers, complete with part numbers. Other than casing things up this should be a pretty straight forward build for a beginner.  
   
  I'm definitely going to go transformer coupled on my build.


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## Lil' Knight

Way to go, Chris.


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## shipsupt

Actually I just ordered everything it turns out to be about $195 for parts *including transformers,* excluding case work.  
   
  YMMV in the US, I used Mouser UK, but that should be a pretty good ballpark.
  Quote: 





fraggler said:


> Still tempted, but looks like it will be $300 before casework if you need the input transformers.  $200 without them.


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## DefQon

Subscribed.


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## CEE TEE

Would like to build this but am thinking that a Crack for my HD600 would be a better idea for me to start at DIY...*unless this amp + HE-6 = awesome value/awesome rig!!!*
   
  Somebody please try it.


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## DefQon

Crack + HD600 is awesome but like yourself waiting for first impressions on the Monolith.


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## shipsupt

Here are the schematics, BOM, build instructions and input transformer specifications.
   
  The amp schematic shows the two ways the amp can be built with the same circuit board. It can either be made as a cap coupled amp, or as a transformer coupled amp.  R5, R12 are not used if the amplifier is wired with cap coupling.


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## DefQon

Is Craig ok with the BOM and such released for those that don't/haven't purchased the board's?


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## shipsupt

Yes.  As per my previous message I checked with him prior to posting it.


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## DefQon

Ahk cool. It'd be really cool if Craig offered an enclosure for sale that matches his other amp's.


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## shipsupt

I'm shopping for an enclosure now... beats working.


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## palchiu

Quote: 





shipsupt said:


> I'm shopping for an enclosure now... beats working.


 
   
  I plan use two Hammond 1455 series, one for amp and another separate power/transformer.


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## FraGGleR

shipsupt said:


> Actually I just ordered everything it turns out to be about $195 for parts *including transformers,* excluding case work.
> 
> YMMV in the US, I used Mouser UK, but that should be a pretty good ballpark.




How much did the transformers end up running? I shot an email to Cinemag but they never responded.

Also, does the kit come with the actual amp chips? Because I cant see them on the BOM. I think they run around $20 a piece unless Im being an illiterate idiot.


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## shipsupt

I like those. 
   
  I thought about separates, but now I'm thinking of using the 1444 series and putting it all in one box.
   

   
   
http://www.hammondmfg.com/dwg21CWW.htm


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## shipsupt

Transformers are $55 each.  They responded to me in a day so I'd expect them to get back soon.
  Quote: 





fraggler said:


> How much did the transformers end up running? I shot an email to Cinemag but they never responded.
> 
> Also, does the kit come with the actual amp chips? Because I cant see them on the BOM. I think they run around $20 a piece unless Im being an illiterate idiot.


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## shipsupt

I think they did... checking.
   
  They should be more like $10 ea. I would think.
   
   
  Quote: 





fraggler said:


> Also, does the kit come with the actual amp chips? Because I cant see them on the BOM. I think they run around $20 a piece unless Im being an illiterate idiot.


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## palchiu

Quote: 





fraggler said:


> Also, does the kit come with the actual amp chips? Because I cant see them on the BOM. I think they run around $20 a piece unless Im being an illiterate idiot.


 
   
  Not with kit.
   
  Craig miss them in BOM, 4xOPA541.


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## shipsupt

595-OPA541APG3 OPAMP from mouser.

You can get them cheaper from ebay.


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## FraGGleR

Quote: 





shipsupt said:


> 595-OPA541APG3 OPAMP from mouser.
> 
> You can get them cheaper from ebay.


 
  Ok.  I'm not crazy   That is what I had found.
   
  I have too many projects on the table right now, but this really intrigues since it looks like a pretty simple build for a very powerful amp.


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## jcx

from the datasheet the industrial OPA5xx power op amps show evidence of crossover distortion - the usual suspect audio power chip amps all have much better dynamic specs, THD vs Level sweeps
   
  for headphone use any of these could be Class A output biased with a ccs or power resistor - which would remove the possible crossover distortion issue
   
  elsewhere when I mention this I keep getting uninformed push back that "THD is meaningless" - which is wrong in this specific case - increasing THD as output level decreases is audibly bad
  Geddes GedLee Metric is peer reviewed controlled listening evidence that this is true
  AP regularly runs seminars with stepped amounts of added distortion in listening demos: clipping - not so bad, slew rate limitning - nearly inaudible, crossover deadband - immediately obvious
  the audiophile  "1st watt" principle, preference for Class A amps is also evidence that this low level distortion is audible and bad
   
  just don't use the opa5xx for audio without added output bias


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## shipsupt

You are not, and your original estimate wasn't all that far off when you throw in another $50 for opamps.  
   
  All parts are incoming, so it shouldn't take long to get this one up and running.
   
  Quote: 





fraggler said:


> Ok.  I'm not crazy   That is what I had found.
> 
> I have too many projects on the table right now, but this really intrigues since it looks like a pretty simple build for a very powerful amp.


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## palchiu

Quote: 





shipsupt said:


> I like those.
> 
> I thought about separates, but now I'm thinking of using the 1444 series and putting it all in one box.
> 
> ...


 
   
  Sweet!
   
  More classical looking.


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## spritzer

Quote: 





jcx said:


> from the datasheet the industrial OPA5xx power op amps show evidence of crossover distortion - the usual suspect audio power chip amps all have much better dynamic specs, THD vs Level sweeps
> 
> for headphone use any of these could be Class A output biased with a ccs or power resistor - which would remove the possible crossover distortion issue
> 
> ...


 
   
  That's pretty much why we never understood why this particular chip was used in the first place.  The favorite Gainclone chips are better and easier to use.  Add to the limited current on tap and this amp is a crap choice for the intended use (HE-6).  It makes them go crazy loud though which 95% of the users here think means "moar powah!!!"
   
  I thought about ordering some Dorkstar boards last week (we've had the design for over a year now) but I ordered some Krell KSA-5 prototype boards instead.


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## shipsupt

Who said anything about "moar power" and the HE-6 as "the intended use" anyway?
   
  Seriously dude, not every build needs to meet your particular set of priorities and preferences!  Not every build has to end up in being the next coming of Jesus. 
   
  Sometimes we do a build just for the fun of it and/or to learn something.


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## FraGGleR

Quote: 





spritzer said:


> That's pretty much why we never understood why this particular chip was used in the first place.  The favorite Gainclone chips are better and easier to use.  Add to the limited current on tap and this amp is a crap choice for the intended use (HE-6).  It makes them go crazy loud though which 95% of the users here think means "moar powah!!!"
> 
> I thought about ordering some Dorkstar boards last week (we've had the design for over a year now) but I ordered some Krell KSA-5 prototype boards instead.


 
  Do you know of some relatively inexpensive (few hundred dollars) and fairly simple kits for a simple board stuffer like myself that might give me better audiophile performance with enough power for something like the HE-6 or K1000?


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## spritzer

If you are comfortable with ordering parts from the likes of Mouser then there are plenty of options.  There are some full kits out there but they are thin on the ground.  There is also whether you want to deal with AC wiring, large heat sinks and the like. 
   
  We have something new coming soon (as in I've already ordered prototype PCB's) and it's a variation of the circuitry found in the Headamp GS-1/X/Glite amps aka the Dynalo.  So fully discrete and only two opamps per board to drive the servo which makes sure no excessive DC voltage ever sees the headphones (as it would kill the drivers).  The design moves in the same direction as Justin's GS-X Mk2 though very different at the same time.  The aim was to move closer to the Dynahi while using easy to find parts.  No heatsinks, minimal matching needed and one Mouser order takes care of all of the parts for the amp boards.  It's also phase splitting so it can take either RCA or XLR inputs and output a balanced signal with no extra parts. 
   
  Quote: 





shipsupt said:


> Who said anything about "moar power" and the HE-6 as "the intended use" anyway?
> 
> Seriously dude, not every build needs to meet your particular set of priorities and preferences!  Not every build has to end up in being the next coming of Jesus.
> 
> Sometimes we do a build just for the fun of it and/or to learn something.


 
   
  This is just a DIY RSA Darkstar and it's intended use was for the HE-6.  Massive amount of voltage swing (a bit less than 160Vp-p) which means very, very, very loud but since this is Ray it's not thought through.  Ortho's are insensitive but they really need current, not voltage, something this amp can't deliver.  All show and no go... 
   
  I have a shelf full of amps that make no sense to anybody but me, improved RSA A-10, fixed WES, too many Egmont type amps to even count and the list goes on.  All of them are terrible designs but I always improve on the clusterf*** that the original manufacturers left us with.  That's why I'd follow JCX's advice and fix the amp and make it better than any of the RSA units ever were.  Either that or build a normal gain clone which is cheaper and will sound better.


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## shipsupt

Quote: 





spritzer said:


> I have a shelf full of amps that make no sense to anybody but me, improved RSA A-10, fixed WES, too many Egmont type amps to even count and the list goes on.  All of them are terrible designs but I always improve on the clusterf*** that the original manufacturers left us with.  That's why I'd follow JCX's advice and fix the amp and make it better than any of the RSA units ever were.  Either that or build a normal gain clone which is cheaper and will sound better.


 
   
  And it's in this same spirit that some of us want to build, listen, learn, then modify.  It's not that we question your knowledge or imply that you're wrong, it's that we want to take the journey ourselves, not just hear about it from others.  Everyone one of those amps was a step in your journey and I'm sure you learned something from each. Why do you discourage people from doing the same thing?  I don't get it. 
   
  As for following JCX's advice, it's what YOU would do.  Great, but that doesn't mean that's the only thing to do!  I for one might follow his advice after I've built what I want to, listened to it, then modify it so I can hear for myself what can be done.  I have other reasons for wanting to build this particular amp, they are mine.  Is that so wrong?
   
  There a better, cheaper, more expensive, bigger, smaller, simpler, more complex amps to build.  I will eventually build some of them, but for now in addition to a few other projects I'm working on, I want to build the Monolith.  I'm sure I will be better for it when I'm done, and I'm having fun while I do it.  
   
  Maybe it will end up on my shelf, is that so bad?


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## DefQon

I think what spritzer is saying is why waste money on thousands of dollars on an amp not designed properly, not following proper engineering when you can build a similar amp following the right principles, that uses the base schematics of what that other amp is based on, save heaps of money and have good sound as well.


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## shipsupt

Quote: 





defqon said:


> I think what spritzer is saying is why waste money on thousands of dollars on an amp not designed properly, not following proper engineering when you can build a similar amp following the right principles, that uses the base schematics of what that other amp is based on, save heaps of money and have good sound as well.


 
   
  I'm happy to wait for Birgir to reply, thanks... but I appreciate your interpretation.
   
  A couple of hundred dollars is a far cry from thousands, and luckily I am not constrained by budget.  I am lucky to be able to not have to restrict myself to a single amp, or building project for that matter.  
   
  After I try this amp both cap coupled and transformer coupled and see what can be done with other changes like those that have been suggested I will likely give it away or use it to drive some little speakers in my kitchen or garage.  It will get used, or it will become a source of donor parts for other little projects.  
   
  After I've gained more building experience and learned a lot about what this amp topology will deliver (and won't deliver) I won't feel like I've wasted my money, even if it's not the best sounding amp in the world. 
   
  I'm not sure if you're speaking about the Darkstar or the Monolith when you make the accusations of improper engineering and improper design?  I can only speak about the Monolith.  I certainly did not see Spritzer make that accusation. Being critical of OPAMP selection or encouraging addition of output bias in the design are critiques encouraging improvement to the circuit, but simply implying that Craig is not following proper engineering practices is a more serious accusation that's not warranted here, or at the least a little extreme.
   
  I was reading a thread from 2009 last night where Birgir was being questioned for why he was doing something.  His reply was simply that he should be able to prove things for himself with his own ears and not follow whatever is written by the masses in threads here.  That's all I'm really wondering, why doesn't that apply to us all?
   
  It's all been done before.  None of this is novel.  Why bother to build anything when I can just ask about it here and have the results explained to me?  
   
  I don't want to keep killing this thread with this BS.  With any luck a moderator will see it and delete it all.  It's passing some time while parts are on order and we can get back to building, but i've got another three boards that I want to stuff this weekend and that's what I should be doing instead of wasting everyones time here.  Sorry for the distraction.
   
  Hopefully those of you with good technical advice will continue to help here, but please leave the discouraging words for another thread.


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## DefQon

I was referring to the Darkstar not this.


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## shipsupt

Thanks, sorry I misunderstood.
  Cheers,
 Chris


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## spritzer

The Monolith is the Darkstar, no doubt about that.  Some small changes here and there but nothing that will make it suck any less than the RSA version.  Now I do think it's a good idea for Craig to offer this to people as debunking the myth of "magical" amps is very much required.  We did a similar board last year but the real intention was not to use it as an audio amp.  That said, I think it is well worth the effort when doing this stuff to improve on the original design to show just how wrong it was. 
   
  Ift's fine that you are building this for **** and giggles but people might think it is a high quality amp. which it clearly isn't.  jcx's post clearly stands then as to what's wrong with the general design and how it can be improved.


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## DefQon

Yeah given shipsupts price so far for the BOM parts and boards is so far at $200, this amp will be a good one to play around with. Interested but how much would need to be changed with the schematics to make it sound best?


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## shipsupt

I'm hoping less than the Dark Star!


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## Hutnicks

I guess what the gist of this all comes down to is.
   
  With so many good designs out there, why would anyone willingly chose to build a bad one?


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## DutchGFX

Well is this a "bad one" lol, what constitutes a "bad one". Is a CMOY bad because is pretty much sucks? No, cause it has its purpose, and its funny in airports. This might not be the best sounding, but replicating a $2700 amp for under $300 is pretty funny.


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## shipsupt

Found a small error on the BOM.

The 4 ea. 5.5k 1/4 W resistors listed on the amp board need to go into R2, R9, R16, and R22

NOT R18

Schematic is right. Order quantities are ok.


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## shipsupt

Waiting for the transformers now.  Hoping customs doesn't hang on to them too long so I can get on with testing.


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## DefQon

Looks smaller than I thought it would. When are the balanced ports going on?


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## shipsupt

I'm pretty tempted to throw some caps in there and run it while I wait for the transformers to be delivered.  Anyone else making progress?
   
  I did test the PSU, all good.


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## palchiu

Should start soldering my this week.


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## shipsupt

I threw a couple of caps and resistors in to get up and running tonight while I wait for the input transformers.  Wired up some balanced in and outs, mounted everything on a temporary wooden base and fired up without a hitch.  
   
  It was sounding pretty good, right up until I pushed the gain up hard.  C7 (10uF 16V cap) on the -15V input side of the OPAMP blew in spectacular fashion, including a nice pop and fire.  
   
  I don't see anything else damaged, but I'll have to do some poking to see what might be going on.  
   
  For the LED I put a 24V green LED in with a 10k resistor (R23).  
   
  I did get a chance to cut the input and raise the gain and it was absolutely silent.  I hope I can keep it that way when I add the coupling transformers and move it from the wood test base to the chassis!
   
  Always good to get one running (sort of), but always frustrating to have to figure why we had a little arc and spark.


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## kevin gilmore

you either had the cap in backwards, or a bad cap.
  tantalums do things like that.
   
  or your power supply was way over 15 volts.


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## shipsupt

Thanks Kevin. 
   
  Checked the cap, it was in correctly, + towards the ground.
   
  I had checked the rails several times before connecting the PSU and during operation and I didn't see any really high voltages, so unless it spiked for some reason I'm hoping that wasn't it.  I did see some voltages around 16V but assumed that was OK?  Those caps are only rated for 16V so not sure what they can take...
   
  So, hoping I just had a bad cap.   Unfortunately I didn't have spares and also took out a resister in the power supply (which hopefully saved the pass transistor).
   
  Parts should be in hand in just a few days.
   
  Still no word on the transformers from CineMag!


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## spritzer

If you followed the BOM then it was a tant.  Personally 'd never use them as when they fail, they really do fail properly.  I'd get some Wima MKS2's if they fit.  Even the 10uf is surprisingly small...


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## shipsupt

It was an impressive failure for such a little part!  
	

	
	
		
		

		
			




   
  Craig mentioned I could increase the size, I'll see what I can find from Wima that might fit in there.


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## spritzer

What is the pitch?  If it is 5mm then even the 10uf/50V MKS2 cap will fit given enough clearance around it.  You could use a much larger electrolytic for this (100uf) but I prefer film caps for this role given how quick they are.


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## shipsupt

I think it is less than 5mm, but plenty of room.

I went with slightly larger tants and changed the Zeners to get my rail voltage down a little. I'm still at slightly over 16V on each side, but everything is running fine now. 

Bad cap, maybe...?

Cap coupled until the transformers show up.


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## palchiu

How about Oscon or polymer? 
	

	
	
		
		

		
		
	


	




   
  I think 16V is too tight, 25V+ for safty.


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## kevin gilmore

Personally I would go with 35v rated tantalums and run 30v rails
Much more fun that way


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## DefQon

Let's hope the whole amplifier doesn't catch fire this time.


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## spritzer

Quote: 





kevin gilmore said:


> Personally I would go with 35v rated tantalums and run 30v rails
> Much more fun that way


 
   
  Yeah, +/-15V is a bit low for the MOAR POWAH function.


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## shipsupt

My Cinemags showed up and the pin spacing is off and the diameter is a little large.  I'm working with Dave (and Craig) to see if we asked for the wrong transformer configuration or if he sent the wrong one. So if you haven't ordered yet, you might hold up for a day or so while we confirm the BOM etc...


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## shipsupt

[size=medium]It looks like the right transformer should be the CMLI-15/15PCA. http://cinemag.biz/line_input/PDF/CMLI-15-15PCA.pdf  [/size]
   
  [size=medium]The pin spacing and diameter looks right.  [/size]
   
  [size=medium]Cinemag is sending a few over to replace those that they already sent, awesome customer service BTW.[/size]
   
  [size=medium]I'd expect Craig to update the BOM accordingly soon.[/size]


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## mcluxun

Ive received my BOM 2 days ago, it said [size=medium]CMLI-15/15PCA on it.[/size]


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## shipsupt

Cool.  That's the right one.  It's been updated.


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## DutchGFX

Anyone got any impressions and or comparisons to dark star?


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## DefQon

lol darkstar.


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## shipsupt

The correct transformers arrived yesterday and I got them into the amp tonight.  Whoa, what a difference.  I'm not sure I'd even recommend building this amp cap coupled.  Much, much better now... 
   
  Time to start fitting everything into a chassis.


----------



## Lil' Knight

Pics please.


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## DefQon

lil' knight said:


> Pics please.




+1


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## palchiu

Transformers is better sound?


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## shipsupt

Much better.  Most notably the bottom end.  I'll post some pics when I'm back in the shop this weekend.
   
  Quote: 





palchiu said:


> Transformers is better sound?


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## mcluxun

Quote: 





shipsupt said:


> Much better.  Most notably the bottom end.  I'll post some pics when I'm back in the shop this weekend.


 
  Hey shipsupt
  I found one place online selling the transformers $88 for 2:http://www.tech-diy.com/Store/TubeStuff.htm
  did you get a better deal from cinemag?


----------



## shipsupt

If that is 2 for $88, that's a good deal.  They were $50 ea. direct from Cinemag.


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## mcluxun

Started soldering.
  shipupt how did you do Q1 and Q2? does polarity matter here?


----------



## shipsupt

Yes, polarity definitely matters on those.  I used a tester and confirmed the pins.  I made sure that the emitter pin was towards R7/R8 appropriately.  it's also important to get the right one on each side, Q1 is NPN and Q2 is PNP.
   
  If you can't confirm the pins on the component you can likely cheat a little using this picture.  The heat sinks clip to metal side of the component.  You can see how they will get aligned in the photo.


----------



## NateH

Just out of curiosity can you wire this amp to be balanced or not balanced input and balanced or not balanced output with the transformers in? I talked to Craig and I know that I can do balanced or not for the input but will it cause a problem on the output if I just plug in a regular old not balanced pair of headphones to the R+ and L+ and leave the R- and L- untouched?


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## DefQon

Looking shipsupts pictures, this amp looks pretty small size wise.


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## holland

Quote: 





nateh said:


> Just out of curiosity can you wire this amp to be balanced or not balanced input and balanced or not balanced output with the transformers in? I talked to Craig and I know that I can do balanced or not for the input but will it cause a problem on the output if I just plug in a regular old not balanced pair of headphones to the R+ and L+ and leave the R- and L- untouched?


 
   
  It's fine.  Do note, you must use the transformer input if your source is single ended.  The volume control relies on a differential input.  You could also use R- and L- for a phase inverted output, it could be interesting to listen to it.  Also, note this on his page.
   
  Quote: 





> -- The amplifier will drive headphones balanced, or single ended


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## mcluxun

Quote: 





holland said:


> It's fine.  Do note, you must use the transformer input if your source is single ended.  The volume control relies on a differential input.  You could also use R- and L- for a phase inverted output, it could be interesting to listen to it.  Also, note this on his page.


 
  That's an interesting idea. I bought 2 neutrik combo jack for output (3pin XLR/ 6.5mm TRS).
  So I could have 2 single end output with inverted phase, and a balanced output too.


----------



## holland

Quote: 





mcluxun said:


> That's an interesting idea. I bought 2 neutrik combo jack for output (3pin XLR/ 6.5mm TRS).
> So I could have 2 single end output with inverted phase, and a balanced output too.


 
   
  Yeah, I don't think anyone would notice.  Besides, some amps invert phase and nobody notices.


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## mcluxun

Power supply problem
  I got +12.54 from the + side and -15.56 from the - side.
  Is there any test point I could measure to debug the problem?


----------



## shipsupt

Sounds like something on the + side only, the - voltage seems about right.
   
  I had some voltage questions when I was building the power supply, Craigs directions:
Check the voltage drop across the series resistor to the zener to see if the Zener is working. Then measure the voltage at the zener. The output from the transistor emitter should be .6 volts less than the zener voltage.


----------



## holland

^
   
  You probably have a 14V zener installed.
   
  1) Also check the voltage at the top of the big cap, just after the rectifier/bridge.  You should measure over 16V, and under 25V.  It should be around 20-22V with a 15VAC transformer.
  2) Measure the voltage drop across the 1ohm resistor.  If the drop is disproportionately large, compared to the negative rail, you have something wrong in your amplifier build and it's pulling lots of current.  I would be surprised if something didn't fry if this is the case.
  3) If you remove the amp from the PSU, you should have similar voltages on the positive and negative rail.
  4) If that's all OK, the zener voltage drop is OK, then the transistor in the PSU is likely borked.  Make sure it's installed correctly.


----------



## amcananey

I just checked my copy of "The Art of Electronics"...I can't seem to find "borked" in the glossary....Can you provide a technical definition?


----------



## kevin gilmore

see Swedish chef.


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## holland

Quote: 





amcananey said:


> I just checked my copy of "The Art of Electronics"...I can't seem to find "borked" in the glossary....Can you provide a technical definition?


 
   
  It's in the unreleased 10th edition.
   
  But, I can provide a visual definition. 
   
  http://youtu.be/br2s0xJyFEM


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## shipsupt

That's nothing like an Icelandic Baker, right? 
	

	
	
		
		

		
			




   
  Quote: 





kevin gilmore said:


> see Swedish chef.


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## DefQon

Quote: 





shipsupt said:


> That's nothing like an * Viking* Baker, right?


 
  Fixed ~


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## kevin gilmore

Quote: 





shipsupt said:


> That's nothing like an Icelandic Baker, right?


 
  not a muppet fan??


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## shipsupt

Actually he was one of my favorites!
   
  And Animal on the drums of course.


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## holland

I liked Kermit and Fozzie.  Statler and Waldorf were up there too.  Waka waka!
   
  BTW, since you're on the thread.  How do you like the amp?  It looks meh, but perhaps it sounds better than one would think.


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## mcluxun

Well
  It looks like my R2 is borked.
  I replaced R2.
  Then the output on the + side is 32 something.
  Ive got following measures
  c6 15.36v
  d2 15.87v
   
   
  c5 32.04v
  d1 32.07v
   
  Is my d1 borked too?


----------



## holland

Quote: 





mcluxun said:


> Well
> It looks like my R2 is borked.
> I replaced R2.
> Then the output on the + side is 32 something.
> ...


 
   
  Resistors don't normally fry, but it does look like d1 is borked now.  Double check that the transistor is working too.  There should be a 0.5V-1.0V drop from D1 to the part of R7 that points toward the transistor (or the output of the emitter).
   
  Your DC voltage is awfully high.  What's the AC you're feeding it?  What size caps are in those positions?  According to the schematic and BOM, those are 25V caps.  You'll likely be replacing them soon.  25V is marginal there, as an unloaded 15V transformer can reach that limit, but 32V is way high.  Your AC is about 23V.  Is that transformer really 15VAC?


----------



## mcluxun

Quote: 





holland said:


> Resistors don't normally fry, but it does look like d1 is borked now.  Double check that the transistor is working too.  There should be a 0.5V-1.0V drop from D1 to the part of R7 that points toward the transistor (or the output of the emitter).
> 
> Your DC voltage is awfully high.  What's the AC you're feeding it?  What size caps are in those positions?  According to the schematic and BOM, those are 25V caps.  You'll likely be replacing them soon.  25V is marginal there, as an unloaded 15V transformer can reach that limit, but 32V is way high.  Your AC is about 23V.  Is that transformer really 15VAC?


 
  R2 is fried for sure. It's charred and resistance is way greater than 100.
  I used the transformer in the BOM it yields 35vac or 17vac.


----------



## mcluxun

Weird transformer problem.
 I dont know if it's unlucky me or everyone else.
 I bought the exact transformer according to BOM, wired as 30vac.
 The output is 38Vac! And my home voltage is ~125Vac.
 The first time I thought it's a defective product so I get another one free from mouser.
 Guess what it's the same thing!! 38Vac.
 Anyone else ran into this problem?


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## shipsupt

Are you taking the voltage with the transformer loaded or unloaded? 
  
 The voltage will be higher when there is no load on the transformer.


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## fzman

you have to look at the percentage regulation, and whether you are measuring rms or peak voltage at the secondary.  Are you measuring the voltage under load, or just by hooking up the transformer with nothing connected to the secondary?


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## mcluxun

It's measured with RMS and not under load.


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## spritzer

With no load that would be normal.  The actual voltage depends on how much current the transformer can handle though.


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## mcluxun

Last time I tried to hook up to some load R8 started to make BBQ.


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## holland

mcluxun said:


> Last time I tried to hook up to some load R8 started to make BBQ.


 
  
 because you probably hooked it up wrong, or your circuit was assembled incorrectly.


----------



## Zashoomin

I was contenplating building this or a Beta 22.  I will be powering LCD3's with it. Has anyone done a comparison by any chance between the two amps.  What is turning me toward the B22 more is the discrete design vs using opamps.


----------



## DefQon

I would avoid the B22 for the LCD3's or any other ortho. PS. I own a B22.


----------



## Zashoomin

defqon said:


> I would avoid the B22 for the LCD3's or any other ortho. PS. I own a B22.


 
  
 May I ask why?


----------



## DefQon

Sounds crap off the B22. B22 + high z headphones is a better match. Although it isn't a problem with the amp delivering inadequate loads just that it doesn't sound delivering it.


----------



## kozmos

Has no one finished the monolith, i wanna see pictures of it


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## shipsupt

I finished everything but putting it in a chassis. I lost interest as I didn't keep any balanced dynamic headphones and had a bunch of other projects.  I've recently grabbed some so I'll have to dig the boards back out and put them into a case.  I've still got one to use that I had originally marked for the project.


----------



## DutchGFX

Debating between this and crack. I have T1's so I know crack would be better match, and I do want an OTL amp, but this just has a certain appeal. How much does everything on BOM cost, including boards. I can do the casework at school for free so that's not an issue. 

So if anyone has total pricing please post


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## DefQon

$200-250 depending on where you source your parts. Think Chris's bom rounded up to about tad bit below $200.


----------



## amcananey

dutchgfx said:


> Debating between this and crack. I have T1's so I know crack would be better match, and I do want an OTL amp, but this just has a certain appeal. How much does everything on BOM cost, including boards. I can do the casework at school for free so that's not an issue.
> 
> So if anyone has total pricing please post




I know you know this, but the Crack is a perfect match to the T1s (even better with the HD800s, but I won't get into the T1 vs. HD800 comparison), whereas the DIY community doesn't really think much of the "Monolith", which was almost created as something of a practical joke. Build what you want, of course, but... 

:rolleyes:


----------



## shipsupt

If you build it cap coupled it would be cheaper still.  That said, I don't think it would do well with the T1's as cap coupled... to me the highs were bit troubled with the cap coupled build which wouldn't seem a good match with the hot treble on the T1.  Transformer coupled it might do pretty well!


----------



## mcluxun

Ive solved the PSU problem. It's pretty dumb I connected +out to +in, -out to gnd and gnd to -in.
 I wired outputs to 2 XLR/TRS combo jacks and tested with a single end earbuds.
 I dont have a balanced output dac so I made my own RCA-XLR cable connecting 1 and 3 to gnd, 2 to pos (my monolith is built with transformer).
 In the testing I got little bit music from the L channel on the + phrase, no sound otherwise.
 And the right side of the earbuds gets hot pretty fast.
 Any hint where should I start debugging?
  
  
 updates: I swapped earphone out and put two 10ohms 25w load on each channel. Im getting 6v dc on each. And the op near L+ gets hot others are pretty cool.


----------



## mcluxun

Got mine finished and running.
 WIDE sound stage!!!


----------



## shipsupt

Two box solution!  Nice.
  
 What headphones are you trying with it?


----------



## mcluxun

Balanced Thunderpants
 some old SE planers as well


----------



## shipsupt

I've been waiting on a balanced cable for my HD-800's to give them a try.  Otherwise I've only used the DT-990, which I sold.  Wondering if I need grab another ortho to try with it as well.


----------



## shipsupt

I finally started laying things out on the chassis getting ready for the mill... but I managed to try the 800's.  Pretty impressive.  I have to agree, super wide open, very precise and clean.  Definitely not for anyone looking for "warm and syrupy". 
  
 Pics as soon as the chassis is done.


----------



## mcluxun

Got a knob for mine.
 I'd like to call it done for now.
 I've noticed my 2 channels were not well balanced at low volume. Same thing happening to u?


----------



## shipsupt

Nice knob!  The whole deal is looking good.  Where's your Eddie Current badge?  
  
 Yes, I'm noticing some channel imbalance at the very bottom, but I think it's below volumes I would want to listen at.  I also don't seem to ever get full attenuation, there is always a little something bleeding through, even with the pot all the way down.
  
 I am looking forward to having it boxed up, it does better with the HD-800 than I expected!


----------



## kozmos

I'm considering building it too, was it a fun build?


----------



## shipsupt

It was fun. It is pretty straight forward/easy putting the boards together.  
  
 Not a lot of options to play with, but plenty of options on casing it up. In fact, it's a great beginners build except that you need to figure out how you want to box it up, but that's not too hard.
  
 I definitely recommend going with the transformers, even though it pushes the build cost up a little, and while you can set it up for singled ended it's best suited for balanced.  IMHO anyway.


----------



## Ony38

Is it possible to have balanced and single ended output on the Monolith?


----------



## mcluxun

Yes
 Monolith has 6 outputs headers L+ gnd L- R+ gnd R-
 you can use L+ R+ for one SE and L- R- for another.
 And when you use SE output do ground them to the board ground.


----------



## kozmos

How much did the parts run you?
 Without enclosure and pcb.


----------



## mcluxun

kozmos said:


> How much did the parts run you?
> Without enclosure and pcb.


 
 Depending on how you build it (transformer input or not)
 And where you get you components
 I ll say ~$200


----------



## shipsupt

Finally got around to boxing up the Monolith this weekend.  Single box.  I only set it up for balanced in, and balance out.  Happy that it stayed dead quiet after boxing it all up.


----------



## DefQon

Internal pr0n shots


----------



## shipsupt

Coming!  I'm done for tonight... time to head to bed!  Work day tomorrow.


----------



## GourouLubrik

defqon said:


> Internal pr0n shots


 
 Week-end incoming : UP for internal pr0n shots


----------



## shipsupt

Here is the general layout.


----------



## Ony38

Nice pics!
  
 How it sound's on your set up?
  
 I starting soldering the resistance on the PCB tonigh and I also plan  to build a buffaloIIIse to match with the Monolith. I will use it with a LCD3 and a TH900 
  
 I will compare it to my actual set up Eddie Current Super 7 + Auralic Ark MX +


----------



## shipsupt

I really like it with the HD800.  Very open and dynamic, if just a bit on the bright side.  I've taken to adding just a slight touch of EQ with this set up.  
  
 I'm looking forward to getting the Slant I ordered to try it with an orthodynamic.


----------



## Ony38

It will suit well with Audeze I think so!

I will buy an Hammond enclosure like yours but in black, which size did you buy?


----------



## shipsupt

I think I went with the largest size available, but I need to check it to confirm that.  I'll post when I get home over the weekend.
  
 You could fit it in a smaller version, but it's not all that big and I didn't want to cramp everything in.  
  
 The only thing I don't like about this enclosure is that you have to wire up with a decent amount of "slack" in the wiring to the top part to allow you to lift it from the bottom where the boards are mounted.  Not a big deal, but it makes it harder to keep things neat.


----------



## Ony38

With the BuffaloIIIse, if I will go for the dual mono version, I definitly need the bigger enclosure. Dimension: 432x254x76mm (ref 1441-32BK3CWW)
  

  
  
 It will be a nice set up with the same enclosure for the dac and the Monolith


----------



## GourouLubrik

@shipsupt Many thanks for the pics
  
 Quote:


ony38 said:


> With the BuffaloIIIse, if I will go for the dual mono version, I definitly need the bigger enclosure. Dimension: 432x254x76mm (ref 1441-32BK3CWW)
> 
> 
> It will be a nice set up with the same enclosure for the dac and the Monolith


 
 Before you order the case ...
  
 Considering that your buffalo build will have AT LEAST 2 trafos, Placid HD, Placid BP, Buffalo Board, Legato, Amanero... I Wonder if the monolith (PSU + PSU Board + Amp Board) will fit... seems big...
 Also:
 Considering that you may go dual mono 
 Considering that you also ordered OPC wire SE-SE, BAL-BAL and 3 PSU 
 Considering that you will want a NTD1 v2 when I got mine that could ruin your legato stackability.
 Considering that you may upgrade buffalo PSU (let's say Salas SSLV instead of placid, OPC shunt instead of trident)
  
 You won't fit il all !!!
  
 You could optimize trafos with a custom big one that will handle everything (from audi*ph*nics)
  
 You should plan it seriously with some paper canva at real size. And consider a big box for your dac alone until you reach the end of DIY upgraditis 
  
 PS: I'm well informed about what Ony is planning


----------



## mcluxun

buffalo+ntd d1+salas+ian fifo
 that's what im working on right now


----------



## Ony38

gouroulubrik said:


> Before you order the case ...
> 
> Considering that your buffalo build will have AT LEAST 2 trafos, Placid HD, Placid BP, Buffalo Board, Legato, Amanero... I Wonder if the monolith (PSU + PSU Board + Amp Board) will fit... seems big...
> Also:
> ...


 
  
 Tsssss, you talk too mutch 
	

	
	
		
		

		
		
	


	



  
 I want the same design of enclosure for the dac and the amp, not putting the amp and the dac in one enclosure !


mcluxun said:


> buffalo+ntd d1+salas+ian fifo
> that's what im working on right now


 

 Nice set up!
  
 I just have two question, for R23, it's only a resistance for the led because I can't find it on the schematic? And for the jumper?
  
 Thanks


----------



## mcluxun

ony38 said:


> Tsssss, you talk too mutch
> 
> I want the same design of enclosure for the dac and the amp, not putting the amp and the dac in one enclosure !
> 
> ...



Id like to know how's the case handling weight.
I was considering having two transformer on the outside like a tube amp.
R23 seems to be the resister for led.
I shorted the jumper.


----------



## shipsupt

R23 is the resistor for the LED, size accordingly for the LED you choose.. You could jump it if you wanted to do an incandescent. 

The jumper should be closed.

That case is strong enough for a few transformers to be mounted on top. That could be an interesting look!


----------



## Ony38

Thanks!

  
 I have to wait for the opamp and the input transformer for ending the amp!
  
 shipsupt, do you already compare the monolith with an other amp?


----------



## kozmos

Has anyone compared this to amb m3?


----------



## mcluxun

oops
 The household voltage in my place has been always on the high side.
 Victim No.1 is one of the diode on the psu. After replacing both of them neither channel is working.
 Hooked up with a oscilloscope every channel looks like this with 1k sine wave input.
 Did I broken all the OPs?


----------



## DefQon

That's nice looking O-scope looking for one myself these days.


----------



## mcluxun

Well, I have to share how I fixed it.
 The amp is oscillating, it appears as output wave when turned on, but soon output straight dc keeps increasing until it's 13v(L- L+ R+ R-) to the ground.
 As I trace the signal with osocpe probe I realize everytime the probe connect to anything along the signal path feeds into the opamp will zero the dc offset.
 Considering the oscope probe as a 1m resistor to the ground I added 4 100k resistors to ground on each signal path before R6 R7 R13 R14. Problem solved.


----------



## Ony38

My Monolith is done but when my potentiometer is at 0, I have sound and I have a difference of 1V between my left and right channel. Someone could check the voltage on the headphone output?


----------



## flying baboon

shipsupt said:


> I really like it with the HD800.  Very open and dynamic, if just a bit on the bright side.  I've taken to adding just a slight touch of EQ with this set up.
> 
> I'm looking forward to getting the Slant I ordered to try it with an orthodynamic.


 
  
 The Monolith is a little bright with the LCD-3 Fazor so I'm pretty sure it's the same with the HD800... But yes it probably sounds really good with the Sennheiser, with a nice soundstage.
 I want to hear it with a LCD2.2 !!!
  
 As discussed with Ony, the next step is to try a better PSU. But firstly, time to order an enclosure...


----------

