Passive Preamps? Anyone?

There is a long thread on DIY forum on the Lightspeed passive attenuator, which is sold commercially by georgehifi (indentified throughout the thread.) His design is based on optocoupler resistors, as formerly used in the Melos photentiometer volume control and more recently, apparently, in a Dart Zeel $20K preamp. The design is not easily adaptable to a balanced system, but if you are running single ended, this may be the most transparent(and inexpensive) passive.

http://www.diyaudio.com/forums/showthread.php?s=ec5a46642aff33baa33bfcf39e01cf07&threadid=80194&perpage=25&pagenumber=61

I think all the information above is very good, not mentioned (unless I missed it) is the music forst which is a TVC and is very nice

I recently did something of a passive shoot out using the Music First copper, Promitheus Ref with Double C-Core, Placette, and both balanced and unbalanced EVO nude attenuators.

I could have lived with any of them happily preferring the Promitheus.

Ultimately I have choosen a tube distinctions soulmate and a TRL battery unit as the ones I will keep. But this is not purely for sonic reasons but some convenience and aesthetics as well.

IMO, the use of passives is very system dependent....if you have the right output from your front end and the right gain structure throughout, can keep the IC's short and preferably use unshielded IC's so capacitance is not an issue the results can be terrific. Now these are important conditions and not easy to meet without other issues popping up.

I run a Canary Audio CA-200 Passive Preamp between a modified Music Hall Maverick CD player and a Spectron Musician amp. I have experienced none of the negatives you usually hear about using a passive preamp. There is nothing fancy about the design and I run it using very short Wireworld gold/silver Eclipse cables.

Are you still using the Paradigm Reference Active 40 speakers? If so and I read the amp specs correctly the line in input impedance is 15k ohms. That is something to take into consideration when selecting a passive preamp. That being said the other posters have covered the gamut on the different brands. Personally I prefer the TVC models over the resistor models as impedance matching is less of an issue.

Another consideration would be the new Pass B1 buffer preamp. It is a zero gain design with a buffer output that offers all the benefits of a passive but eliminates impedance matching issues. It's listed here on Audiogon for about $875 new IIRC.

With that 15kohm inout impedance I would only go with the Pass B1 Buffer, not quite passive, but awfully close. For some reason the GON consensus seems to be that TVC and AVCs (I've owned both from Bent and K&K, as well as the Placette Active and RVC)are always better than resistor based passive. With my Cardas GR IC (very low capaitance) and Music Reference RM9 Special Edition I find the Gold Point Volume Attenuator SA1 works just as well to my ears. Plenty of soundstage, dynamics, and clarity. The technoids can proabably explain it better, but I get the sense that TVC and AVCs are also problematic, though they do provide a partial solution to impedance mismatches. To my ears, with properly matched source and amps, the resistor-based attenuators are undeniably simpler, purer, and capable of even lower distortion - but they do have to be in the "right" system for them to perform their best.