Transformer volume control preamps

[Philidor]

A number of expensive passive preamps use transformer volume controls instead of stepped attenuator controls.
The Music First Audio Pre Amplifier and the Townshend Allegri preamp cost over 2 grand.
Do transformers or autoformers have any real sonic benefits? Or are they an over engineered waste of money?

[Dr Bunsen Honeydew]

They work and some people like them. I tried and I don't like them. Any transformer in the signal path has a sound, basically because a transformer is a coils so is also an inductor. And each of the separate tappings (change volume) have different inductance and in smaller quantities capacitance and resistance. So it is the old LCR problem again.

A stepped attenuator passive and a pot passive both just have resistance in the signal path so do not influence the sound in terms of tonality, transformers do.

[Philidor]

Does your P50sa preamp use the Glasshouse shinkoh/elma 24 step attenuator?

[_D_S_J_R_]

All audio transformers add distortion and band limit to a degree. My Micro Seiki CD player sounds better when outputted from the transformer coupled balanced outputs (a separate board with the four op-amps, two transformers and some poly caps fed and powered from before the Philips/Marantz audio outputs), but I believe this has as much to do with the transformers absorbing rf and/or 'digital nasties' as putting ferrites on stock interconnects from the basic L/R RCA outputs closes the gap somewhat.

Re the stepped attenuator used by NVA. Not sure which one, but it's well made and bloody expensive!

[Dr Bunsen Honeydew]

Does your P50sa preamp use the Glasshouse shinkoh/elma 24 step attenuator?

No, the P90 uses mono ones of that. The P50 use a cheaper switch (as good to my ears) and Takman metal film resistors.

[zebbo]

Well the Doc's ears are better than mine.
I owned a Music First when I first got my A80's. I played it off against the P90sa and couldn't really split the two so sold the MF for more than the P90sa cost and pocketed a few hundred quid.

[Dr Bunsen Honeydew]

I think that MF one is supposed to be the best of the bunch. I bought a couple of transformers to try from Hi-Fi Collective, I think they are same ones they use but not sure.

[zebbo]

Well considering that the Music First Classic is £1700 plus VAT, I think the fact that I couldn't split it on sonic grounds from your P90sa says it all really - nice one Doc.

[jammy395]

A passive is a fukin passive........

wtf......Discuss

How much in yer face ya dont want.... it depends on yer fukin wallet.

VW v Skoda

[paskinner]

It's not so simple....there's a reason why sales of TVC preamps have risen steadily in recent years. They will drive any power amp, assuming adequate sensitivity. They don't have the impedance matching issues which plain passives have in some mismatched systems. Often tvcs do sound better, but not always. People don't buy stuff like MF because they are dumb. And Mf don't sell their main transformers to other suppliers, they do sell rather cheaper, smaller, ones.
I sometimes us a Tisbury, which sounds fine...but a good TVC sounds quite a lot better in my particulat system. Overall, I still prefer an active preamp , again, in this specific system. There's no 'one size fits all'' guarantee here.
So, try it and see. A basic passive may be fine, and a lot cheaper, but you might find the TVC is a better match. Depends.
BTW Philador..are you a chess fan by any chance? The Modern Philador is my favourite opening. Trouble is, I lose a lot....