Hi,
anubisgrau said:
T, do you maybe know if transformers in bent NOH are the original S&B, or they are made by john chapman according to S&B specs?
Bent Audio is an OEM Customer of S&B who gets his own specification. They principle winding geometry is the same but some materials used etc. vary between Bent Audio Spec Transformers and others.
Read Sarjans review (6moons.com) of the Audio Zone Passive Preamp compared to MF Audio to get an idea what sort of differences apply in sonic terms.
In electrical terms the main differences are between the different "Mark's", there was the original MK I (very rare), the MK II which changed the winding system substantially for better measurements sadly loosing a little bit of sound quality in the process, the MK 2.5 which clawed back some of the losses and finally the current MK III whcih uses a completely new and unusal methode of winding transformers JB cam up with.
As John Chapman said, there are audible differences between the "Mark's", but not large enough to warrant changing transformers. The reviews in HiFi World (David Price) and HiFi News (Andrew Harrison) of the Music First Passive Pre used MK II versions of the TX-102....
anubisgrau said:
and does it really matter?
Depends. I had originally a hand in getting Sowter to make the first TVC's (this was a very sad story, but anyway). We (as in associates of mine and myself) found the original Sowter TVC to be significantly better in several key performance areas, over resistive attenuators of varying types, but attended with a slight softening at the audio band extremes, somewhat source dependent.
When I got to meet and know Jonathan Billington I originally merely commisioned him to make me a trial set of Moving Coil Stepups and also of Transformer volume controls, derived from the TX-101 Line transformer, which had mightly impressed me and which I felt would cure the problems experienced with the Sowter Transformers.
In fact, my original sets where swiped by a very famous and contentious manufatcurer who is a major OEM customer of S&B, by the time my own stuff arrived JB had already asked if I really minded if he started making both the MC Stepup (now the TX-103) and TVC (now TX-102) commercially, which I did not (of course).
Based on experiences among my associates quite a few TX-102's where sold to DIY'ers (in preference to Sowter's early versions despite the much higher cost of the TX-102) in the UK and John Chapman (who I know somewhat from the Days of Sound Practices) also picked up on these.
The rest I guess is history.
You can find a number of comparison tests between Sowter and S&B TVC's, in addition occasionally to others. In addition S&B undertook a quite substantial program of development on from the origianl TX-102 which has lead to the current 102 MK III. In that process (in which I had some small input) all sorts of angles where evaluated. The current MK III is probably about as good as S&B can manage without a major breakthrough in winding or core technology.
As the BBC used to say, "other options exist".
Ciao T
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