Transformer volume control

I have two. One, a Promitheus is excellent, the other, a Ming Da MC-9 is amazing!

I own a nice little Quad 306 and finding a matching (non Quad) pre-amp was tricky, but the Promitheus suits it just fine.

The MC-9 is used with my EL34 valve monoblocks and is the most lucid pre-amp I've come across. It outperformed the VTL Deluxe and Forte Model 2 I'd been using.

Neither TVC is lacking in body, dynamics or bass extension and both are very open and detailed with no top end nasties at all.

A friend had one in his system, I can’t recall which one it was right now but it will come back to me. It’s always hard to be sure when it’s nit your system, but I do know his room well and ive heard a lot of stuff there. The system with ten TVC sounded “alive”. The opposite of what I find from passives the majority of the time.

I’ve used a couple of AVC’s. First I had was pair of the Slagles-

www.intactaudio.com/atten.html

Scroll down the page a bit, a pair of the bare autoformers are $200, which I reckon are one of the biggest audio bargains around as these sound great. I built mine into a normal passive pre I already had. Good thing with these is you can restack the laminations to alter the inductance if it’s not sounding quite right in your system.

I now have a set of Tributes, which I got my mate Ant of BTE designs to put in a nice box for me. Don’t have the Slagles any more to compare, but Tribute make some of the best transformers on the planet, this sounds superb.

Thanks Andrew and Ali.

I will have a read of your aos thread. Are tribute transformers available to buy anywhere ?

And anyone know what the hifi collective ones are?

Cheers, Stu

I've heard a few including the Slagel one Ali built and the Music First ten grand job.


The Music First I couldn't distinguish from the NVA P90SA so where the additional 9 grand goes I've got no idea.


The Slagle had a different character and stood out a bit from the other passives we tested. It seemed a little sharper and brighter, not in bad way, more attack on the leading edges so acoustic guitars, cymbals, snares had a bit more bite to them. I'd like to have bought it when Ali sold it but I was having a moratorium on buying kit at the time (too much piled up) so I missed it.


On paper sticking a traffo in there will increase distortion over a traditional stepped attenuator passive, but in practice this was not noticeable at all. The thing about matching a passive to a power amp is mostly horseshit. You get the occasional amp that isn't sensitive enough to get enough volume but that is very rare IME. So I'm not sure what the advantages are really and they do tend to be pricier than an SA passive.

'one theory is that it's because an autoformer doesn't attenuate by wasting energy'

Okay, but then they don't go on to offer anything tangible to back that up at all except a car analogy. Nowt wrong with a car analogy but I need more than that.

'The simple answer is that most people find that the autoformer volume control sounds significantly better than even the best potentiometer or stepped attenuator. And it's not a subtle difference.'

I agree it is not subtle difference, it is pretty obvious from bar one of the music, but have to say I didn't find yours 'significantly better'. Just different. Which I'd prefer I don't know, would have to live with an autoformer passive for a while in my own system before I could answer that. 

I'm not sure how an autoformer is different from a transformer. I should probably look that up except I spent most of the afternoon trying to understand Sigma Six and my brain is a bit fried.