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.



I ended up purchasing the icOn 4PRO balanced unit, which has four Slagle autoformers (copper). It is supposed to arrive tomorrow and I look forward to trying it in my system, both as a stand-alone preamp and also as a volume control in front of my SMc unity-gain buffer.

I have been using a Hattor passive preamp (Amtrans AMRG resistors) in front of the SMc buffer for a pretty good sound, and recently tried swapping the Hattor for a Goldpoint passive (SMD resistors) I still have here. Both sound good with the Goldpoint providing a bit more precision and the Hattor providing a bit more body and smoothness - maybe due to the carbon film vs. SMD resistors?

An equipment manufacturer I know has stuck with resistive preamps and told me, in his opinion, "TVCs sounded excellent with simple material, but started getting a bit irritating and “confused” with complex, dynamic music. Ymmv." I notice he said "TVCs" and not "AVCs" so I don’t know whether there will be a difference between the TVC units he has heard and the AVC icOn unit. I also don’t know whether he used the units alone, or in front of an active buffer, or both, and whether that even makes a difference. I will give it a try.

I’m in the process of building a simple avc attenuator with the budget autoformers from Slagle. To be used with my Sayes SET and Omega single drivers.

2 inputs with a switch and 2 outputs

vintage 16 step rotary knob

progress pic HERE  and FRONT

Really looking forward to finally being done with it.

Still need to put in the rca connector and wire it up.

@j_andrews I use slagle passive in front of oliver sayes with omega speakers! Your build looks nice 😊 

@j_andrews - Nice work!  I like the use of a stepped switch.  Thanks for sharing.
I wish I had the knowledge, then I would do a similar but balanced unit - very simple with one input and two parallel outputs.  The main complication would be that I have come to like having a remote and display, which would add complexity to the build.

@jmolsberg That's great, how do you like it?  What is your amp?  Do you feel the autoformers have a sound or not?  Can't wait to wrap this thing up..just need to set aside some time to inhale some soldering fumes.

@mitch2 , Yes all the Slagle autoformers would require a stepped switch as you're actually connecting to different taps on the autofomer,  As I mentioned, I purchased the most basic units which are only 16 not a lot of resolution between volume steps but I think I'll be OK with that as I usually set it and leave it alone.

At one point, he did offer some sort of collaboration with Bent where there was a remote control unit but I don't think that's available anymore.