Active Stereo Preamp , OPAMP VS TRANSISTORS , which on would you prefer ? - diyAudio
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Old 9th May 2012, 08:02 PM   #1
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Default Active Stereo Preamp , OPAMP VS TRANSISTORS , which on would you prefer ?

Hi all , Preamp is very important and has critical affect on the amplification and sound quality .
which topology would you prefer to build(buy) a stereo preamp ?
with OPAMP ?
or maybe Transistors ? ( bipolar ?fet ? class A ? class AB ? )
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Old 9th May 2012, 09:24 PM   #2
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Originally Posted by WhiteRhino View Post
bipolar ?fet ? class A ? class AB


Class AB in a preamp? You can't possibly be serious. Even opamps usually stay within class A in preamps.

IMHO topology in a preamp is not nearly as important as implementation: attenuator type and quality, raw power supply, regulation, etc.
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Old 9th May 2012, 10:14 PM   #3
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of course implementation is very important .
but which preamp topology would you prefer ?

or you are just saying that can be wonderful preamp in opamp and in transistors as well
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Old 9th May 2012, 11:26 PM   #4
Simon B is offline Simon B  United Kingdom
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Originally Posted by analog_sa View Post
.....Even opamps usually stay within class A in preamps....

Do they?

Not that I think the OP need worry about it, and certainly class A for any discrete devices.
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Old 10th May 2012, 02:53 AM   #5
adason is offline adason  United States
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Active Stereo Preamp , OPAMP VS TRANSISTORS , which on would you prefer ?


tubes...

Last edited by adason; 10th May 2012 at 03:01 AM.
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Old 10th May 2012, 06:18 AM   #6
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Originally Posted by WhiteRhino View Post
or you are just saying that can be wonderful preamp in opamp and in transistors as well
Absolutely. Provided both are built with sufficient care and appropriate parts selection. They will certainly not sound the same though.

Fwiw mine is a tube pre as i find tubes deal more gracefully with digital sources. If i have to i could switch to an AD797 or AD815, or even an opa627 based pre without losing too much sleep. Otoh, switching from a Shallco stepped attenuator down to an electronic pot or a simple Alps would be much more traumatic.
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Old 11th May 2012, 07:05 PM   #7
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Originally Posted by analog_sa View Post
Absolutely. Provided both are built with sufficient care and appropriate parts selection. They will certainly not sound the same though.
Fwiw mine is a tube pre as i find tubes deal more gracefully with digital sources. .
I've got a legendary tube pre, a dynakit PAS2, and a disco mixer (op amp) that I heavily modified to stop hissing and humming. The 100 watts it takes to run the PAS2 is not worth the very slight improvement in hum. The mixer has the advantage, I can leave all the inputs on at the same time and not switch around. Also, on the disco mixer I don't have to turn the volume pot with vise-grip pliers, as mil-spec 250k log stereo centralab pots are no longer available.
Within the limits of my 40 db down on 2nd harmonic distortion speakers, both sound the same on the CD player, except the disco mixer has a little more hum. I'm using ST33078 op amps now. For the next act, next winter, I'll change the RIAA network on the disco mixer from .0033 cap and 1 meg feedback resistor, to .033 cap and 100k feedback resistor. Will take a shoehorn to make the cap fit, though.
The cheapest I've seen a PAT4 transistor pre on craigslist (used, not refurbished) around here has been $100. I bought the disco mixer for $15 and put $20 in parts in it. And 9 months of experimenting. Improving a "Disco mixer" to mid-fi performance
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Last edited by indianajo; 11th May 2012 at 07:07 PM.
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