Yeah, I made my first CMOY
May 19, 2002 at 10:50 AM Post #16 of 26

tangent

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Rolling op-amps isn't hard at all. You just have to make sure you get dual DIP-8 op-amps with standard pin-outs. (That's what your 2134 is now.)

Many very good op-amps are available only in single-channel varieties or in surface-mount packages, so check first. If you just gotta have one of these chips to plug into your amp, there are adapters available. Do a search here -- they've all been mentioned recently. All of the adapters take up more space than a bare chip, some more than others, so make sure you've got the spare space.

I've reviewed a lot of op-amps in recent months. Those reviews link to other good reviews I've found here at Head-fi and at Headwize, so you don't have to take my word alone about these chips. Remember, this is all subjective, so take my reviews with a grain of salt. Also, don't overlook the fact that I'm deliberately torturing these chips: I use low-impedance headphones, a portable CD player, difficult music, and then (after all that!) start ramping the voltage down! If I say a chip sucks when given less than 10V, that doesn't mean you can't drive it from a 9V battery under some conditions. It just means that in my torture test, that's where it started failing.
 
May 19, 2002 at 10:58 AM Post #17 of 26

millerdog

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Man, now I got a lot of questions...but I think I'll just save em until the tip gets hot and solder starts to drip!
This is getting deeper than just schematics and morse code!
thanks tangent and mkyy,
md
 
May 19, 2002 at 11:34 AM Post #18 of 26

Jeff Guidry

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the AD832 seems to be the only direct replacement that will yield sonic benefits, but I use exclusively low impedance headphones with my CMOY. I have no interest in sticking buffers in (wouldn't know what they were or where to put them
wink.gif
) and your info indicates that this chip would be a bad match with low impedance headphones unbuffered.

I didn't see any other chips on your list that would fit my configuraton without an adaptor that would yield any sonic benefit. Yes?
 
May 19, 2002 at 11:55 AM Post #19 of 26

tangent

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Yes, the 823 is a touch weak with low-impedance headphones. I think it's still enjoyable, but I've not spent a whole lot of time listening to one with Grados. I'm a Sennheiser guy, mainly, and for that the AD823 is just fine alone, IMHO.

It does seem that you get into single-channel-only chips beyond a certain performance level. There are probably still some nice duals I haven't discovered yet, though... There are several nice duals in SO-8 form, but that's just a different kind of adapter, no help to you there...

I guess you're probably stuck with pioneering some new-to-us chips or getting adapters.
 
May 19, 2002 at 12:33 PM Post #20 of 26

Jeff Guidry

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I may be getting the Beyer 770's soon, so I may just be doing some chip rolling to optimize it's sound.

Anyway, thanks for the info.
 
May 19, 2002 at 8:20 PM Post #21 of 26

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What op-amp does JMT use in his CHA-47's?
 
May 19, 2002 at 8:24 PM Post #23 of 26

tangent

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I think he uses the OPA2134 most often, based on the posts about JMT amps I've seen. I'm sure you could talk him into using something else, if you wanted.
 
May 19, 2002 at 8:26 PM Post #24 of 26

tangent

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You are indeed lucky, mkyy! I've killed four op-amps in the past few months by fiddling inadvisedly with the rails.
eek.gif
 
May 20, 2002 at 12:52 AM Post #25 of 26

jarthel

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Quote:

Originally posted by mkyy
oh yea, made my first CMOY.
biggrin.gif
biggrin.gif

too excited! Just wanna share the joy!!!!
Thanx tangent for you excellent tutorial.
man, this is addictive, I'm already planning my next project.

What your suggestion for my next project?

Cheers


Try Kevin Gilmore's Pure Class A amp. It's a discrete design. Very nice sound! I have build one myself and few other people.

Go to Headwize for project article.

Jayel
 

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