[baco99]

I just purchased a very nice, nearly professional, DIY build of a BOSOZ, Balanced Zen Line Stage, preamp from Nelson Pass. 
Literature here:
http://www.firstwatt.com/pdf/art_bosoz.pdf

I'm wondering what amp would be best suited for this preamp.  I have some amps on tap already that I could employ, but not sure any of them would be the best match for the BOSOZ.  I have an Amherst Audio A-2000 (Early Steve Kieser design similar in topology to the Luminance LST-150).  I also have an Adcom GFA-545 Series II.  And a pair of Tube Audio Design "Hibachi" solid state mono blocks.


Wondering if I should avoid any of these three or embrace them.  Ideas? Thoughts?

[DaveC113]

It should be able to drive most any amp, but the issue is gain, and the fact you'll have too much of it for most amps if it was built for 20 dB gain. You can adjust the gain down to 10 dB, I'd either do that or increase it to max, around 30 dB, and use it as a driver circuit for a power buffer amplifier like an F4.

[baco99]

That's what I suspected.  However, it seems the output voltage at 20 dB gain is about 1V, which for the Adcom anyway is within the range (max input voltage recommended is 1.25V).

[poseidonsvoice]

That's what I suspected.  However, it seems the output voltage at 20 dB gain is about 1V, which for the Adcom anyway is within the range (max input voltage recommended is 1.25V).

Don't forget to take into consideration the output voltage of your source. Most digital sources are a minimum of 2V RMS. So even at 10 dB gain, you are talking about ~ 6V, which is plenty for all amps IMHO. Of course if you are using P1, P2 to attenuate the incoming signal then forget what I just said!

I would go with lowest gain version, which will provide you with the lowest noise as well. A differential source and a differential amp will also help given that this preamp is differential. The output impedance of this preamp is 1000 ohms if I recall. This preamp has decent CMRR, take advantage of it.

If you are into DIY, play with different output cap types, I believe they are 10uf here. There are many other tweaks to this design, pm me if interested. I agree with Dave, it would be nice with a follower circuit like the F4.

Best,
Anand.

[TomS]

With the voltage rails this preamp can swing, it would be sweet with one or two FirstWatt/DIY F4's, as Dave said. They have zero voltage gain, but the preamp should provide plenty.

[baco99]

I'll look this up.  Another amp choice would be a NAIM 120 clone.  I have the kit, just need to piece it all together.

I may also look into the 10 dB gain version to see if this pre can be brought back "down" to that spec and make it more accepting of other amps.