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Eddie Current DIY amplifier "Monolith" - Page 4

post #46 of 172
Quote:
Originally Posted by shipsupt View Post

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.
post #47 of 172

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

post #48 of 172

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

Quote:
Originally Posted by FraGGleR View Post


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.
post #49 of 172

I think they did... checking.

 

They should be more like $10 ea. I would think.

 

 

Quote:
Originally Posted by FraGGleR View Post



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.
post #50 of 172
Quote:
Originally Posted by FraGGleR View Post


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.

post #51 of 172
595-OPA541APG3 OPAMP from mouser.

You can get them cheaper from ebay.
post #52 of 172
Quote:
Originally Posted by shipsupt View Post

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. 

post #53 of 172

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


Edited by jcx - 5/17/13 at 1:38pm
post #54 of 172

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:
Originally Posted by FraGGleR View Post

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. 

post #55 of 172
Quote:
Originally Posted by shipsupt View Post

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

 

Sweet!

 

More classical looking.

post #56 of 172
Quote:
Originally Posted by jcx View Post

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

 

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. 

post #57 of 172

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. 

post #58 of 172
Quote:
Originally Posted by spritzer View Post

 

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?  

post #59 of 172

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:
Originally Posted by shipsupt View Post

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. 

post #60 of 172
Quote:
Originally Posted by spritzer View Post

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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