Is an autoformer (AVC) always superior to pots and resistors ?

This is an argument some of my friends made to me. AVC is always the best volume control, better than anything else such as rk50 or resistor based volume controls. Have you found this to be the case?

I am also curious why AVC is not implemented more often in high end audio preamps / integrated amps.



no softened transients here with my slagle autoformers. wonderfully impactful at low level listening, which is my preference.


@sns - Your Coincident Statement MkII pre may use autoformer volume control pots but it is an active gain preamp using DHTs to provide 13dB of gain.  That is a whole different kettle of fish than what those report hearing from “passive” autoformer preamps such as the Bent Tap X, JaySho, or icOn Pro4 where the only gain(if any) comes from the autoformer transformers themselves.  I am not surprised you like what you hear from the active Coincident Pre.

@sns, Mitch is correct, it is not the same. I am speaking unity gain, and my experience is exactly as stated. @mitch2, with a unity gain passive device, the gain is provided by the source, your last statement is unclear to me. sorry....... 


I think the semantics can get tangled when discussing this stuff.  Plus, I do not have that much experience with TVC or autoformer preamps.  My SMc buffer is designed as an active unity gain buffer.  The input voltage is very close to the output voltage but the active stage prevents impedance mismatches and helps control the interconnect cables. 

My buffer does use output transformers to provide balanced operation, and the designer could have set those for up to 6dB of gain instead of the unity gain that I chose.  I believe the older Bent Audio Tap X was set up for +6dB gain, resulting from the transformers.  I assumed it may be possible to set up autoformers the same way, but I am not sure.  I still wouldn't consider that an active stage but others might.  Below is a quote about transformers and gain from a review of the Music First TVC preamp:

The transformers have dual primaries, allowing them to be connected in series as a step-up device offering the +6-dB option, or parallel as a 1:1 transformer.  Bear in mind that selecting the +6-dB option does cut the range of attenuation by an equivalent amount, but it also allows pairing with older components with lower outputs. It can still drive your power amplifier to full output, and sound quality is not compromised in the least by selecting this option.

If your question was about my comment about the Coincident preamp, I would not be surprised if an autoformer volume control in front of a low'ish gain active stage could sound quite good.  That is what I am considering doing with the icOn 4Pro in front of my buffer.

@mitch2 I apologize for my misunderstanding. I commented based on your statement " where the only gain ( if any ) comes from the autoformer transformers themselves ". If designed with +6 db gain, yes, but we are talking unity gain, so the source creates the gain. My best ! Always, MrD.