PPA v1.1 Finished, Very happy!
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bubbamc119

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Well I finally finished my ppa today and steps power supply. It has black gates all round and glassmans diamond buffers with ad8610 op amps. I'll post pics soon. I love this thing.
 
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ppl

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Glad you have your amp working great for you and Yup Glassmans Buffers sound pretty good IMHO
 
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saturnine

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Exactly like my PPA
Damn nice amp, please post pics!
 
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Stephan

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What difference in sound do the glassman diamond buffers make?
 
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bubbamc119

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Here's some pics for your evaluation, this being my first serious audio diy project (Have put together many a kit though in highschool).

I am enjoying this amp very much, the AD opamps seem very well suited to classical music and high res recordings (DVD-A) IMHO. I now know what people mean when they say that the AD8610 sounds analytical!

I have been comparing the sound from the ppa to the headphone out on my 1980 Marantz PM-6 Esotec integrated, and I actually like the Marantz sound better for the most part with CDs - it seems more lush and rich than the ppa and has fuller extended bass, except that it has an annoying low level buzz. I imagine it would cost me an arm and a leg to fix the Marantz - the filter capacitors on it cost over $500US! Hence the reason for building this ppa in the first place.

I'm going to try burr brown opamps in the ppa soon to see if I like them more. That said I'm going to let the ppa burn in for a while and re-evaluate. What I do love about the ppa though is dead silence when the music is silent, with no hum or buzz whatsoever.

Does anyone have any advice on which other opamps to try to get a richer sound and if burn-in is an issue with the ppa?

Thanks for looking!
 
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Glassman

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I really enjoy AD744 with bypassed output stage in my own amp, really wonderful and works great with my buffers.. and they don't cost a fortune also..
 
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Voodoochile

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My PPA also uses the 744s configured that way. I like them a lot.

Otherwise, my preference is for 637s in L/R and 627 in the ground channel, gain of 6 overall.
 
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ppl

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Well this makes three with the AD744 comp pin set up yes why have an output stage droving another output stage when you dont have to, Just simply bypass the opamp's internal output stage using the comp pin and you have a Pure class A Voltage gain stage driving the PPA's buffers. BTW i like the AD8065 Better than the AD8610 in sound but YMMY
 
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bubbamc119

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2 questions,
Are the glassman diamond buffers class A ?
Are there any other opamps available with the internal buffer bypass feature that are suitable for the PPA?
 
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Glassman

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although not a classical class A circuit, they fulfill class A by it's definition, the outputs never shut down at any time.. there is a constant current load in addition to classical (very open) class AB biasing..

other opamps exist, not easy to get though as they are discontinued for a long time now I believe..
 
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steinchen

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Quote:

Originally Posted by ppl
Well this makes three with the AD744 comp pin set up ...


4

got it running in my second PPA v2, nice clear analogue sound, definitely one of the best opamps available
 
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__redruM

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Are the Glassman buffers still available? I assume that they would be hard to find with PPA v2 out, but I would be interest in 3...
 
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Glassman

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there's a whole bunch of them still available, contact bg4533, he has them all with him in US and unlike me he can use PayPal..
 
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