Passive preamps - differences between technologies


I have been wondering what are the main differences in the way some passive preamps are designed. 

Some have resistors, some are transformer based.. What are the pros/cons?

More specifically, I'm looking at Music First Classic/Baby Reference V2 vs Hattor the Big or a Tortuga.

I'm looking for an upgrade from Audio Research LS16, considering looking for ARC Ref3 or a nice passive. My amp is ARC Ref150 (which is a lovely thing and I feel like the LS16 is holding it back) and phono pre is RCM sensor2 mk2 - so there's enough gain from the phono, the power amp has 300k ohms input, my DAC can output 1-3V rms, I use interconnects up to 1m so a passive could be an option. 

Thank you. 

Greetings from Prague with the first snow



Hello filipm!  If your speakers are sufficiently efficient, and your amp is sensitive enough, you are wise to skip unnecessary electronics. That's what I do in my demonstration/lab system. Why put money into something you don't need. Mine is a simple volume control with six sets of dual RCA plug inputs chosen by a switch with silver contacts. Enjoy the music!

Yes, the Hattor passive with discrete shunt attenuator is quite good. I have/had 2 of them, the pure passive and the dual mono buffered. The buffered version requires some discrete OA rolling to get the best results (of course). Industrial OA just don’t cut it IME.

Transformers/magnetics do also impose a signature IME. I’ve also had AVC and TVC passive pres. IME, resistor shunts much less so, with wonderful organic naturalness. But alas, the dynamics can be boring unfortunately.

Nor do the magnetic pres solve the issue of coloration vs needing buffering. They might couple the signal a little better than a resistive passive, and I say "might". But the coloration imposed in the process doesn’t cut it IME. OTOH the passive shunt atten definitely needs buffering in most cases.

But that raises the question of exactly how to buffer such that it works the best with 0 ~ coloration. A tall task, and have been working on it personally for years.. But lately that has been solved very nicely via a) an optimized impedance shunt attenuator, b) utterly amazing, no distortion, no coloration, no global feedback discrete buffers that can also drive pretty much anything and c) the topology, ie where exactly do you place the buffers (and where not).

What we need is, the glorious organic, uncolored naturalness of the passive shunt attenuator with say, Z foils. But also the perfect dynamics of a (properly) buffered version. Eureka, it’s been solved and it’s a game changer.

I said "had" the Hattor above because the passive was converted to the above eureka buffered pre a few months ago and my high end audio bud in Dallas wouldn’t let me return home with it. Sold already, the first day of its premier demo lol. And he can use anything; it displaces an expensive Esoteric setup (and a few others). Yes, it really is that good.

Just sharing my experience. Not trying to step on any toes here. YMMV.



The Luminous Audio has the shortest signal path of them all. Just saying. Enjoy, MrD.