Experiences with S&B102 TVC

[analog_sa]

http://www.audioasylum.com/audio/twe...ges/77989.html

[Bas Horneman]

Hi Peter,

The TVC has some issues..apparently it needs the right application to sing.

On a different note. I have seen many posts by people that have heard both...i.e. Sowther and S&B prefer the Sowther..

Anyway, thanks for saving me some bucks! ;-)
Cheers,
Bas

[analog_sa]

I keep on wondering how much has the mu-metal shielding got to do with the pronounced sonic character. Might even try to take it out.
The concept of TVC will become genuinely interesting when someone manages to get sufficient performance combined with an airgap. Even if it's a 5mA airgap.
After this experience i am not likely to look at an even more compromised design as the Sowter. Even if the price/performance is very likely better. It's amazing how quickly the S&B raised their price with the increase in popularity. Especially taking into account that even their greateast apologist Sayonara-Thorsten admits the old cheap ones sound better.


regards

peter

[jeff mai]

I really like what my autotransformer attenuators do for my system. It was the single biggest improvement I have ever made in my system. It does seem very system dependent. It hasn't impressed at all in other people's systems.

Have you tried wiring up yours as an autotransformer with the windings in series? If you don't need the isolation of a transformer, an autotransformer offers some advantages (no interwinding capacitance or coupling issues.)

[analog_sa]

No, i haven't. I briefly compared a common i/p-o/p ground to see what benefits the isolation will bring and was happy to confirm that isolated sounds better. To emulate autotransformer i need to put primary and secondary in series?
My main gripe is the 'filtering' and 'slowing down' effect. Doesn't every transformer do that to a certain extent? Permalloy/amorphous cores are probably less guilty.


cheers


peter

[Bas Horneman]

I wish I could say this from experience. But alas. Mostly transformers have some vices but lack of speed is not one of them.

[jeff mai]

I'm assuming the S&B uses one secondary with multiple taps. If so, then wiring the primary in series with the secondary will result in an autotransformer. You then just pretend like it is all one winding. Input and output common attach to the free end of the secondary, input signal at the free end of the primary and attenuated output signal off the taps.

BTW, my attenuators do have an 80% nickel core. What is the core material for the S&B?

[Brett]

Hi Peter,

I like my 102's a lot, but it's hard to give a comparison between them and the stepped attenuator I had previously. The SA was between the phono and line stages (just after source selector) and the 120 is at the output of the linestage, which was also changed to a lower gain one in the process for different reasons.

I agree about the S&B pricing policies, but I bought mine early in the peice at a very good price, so I could always resell it at small loss if I wanted to. In fact I may do just this as I'm thinking about adding a delay network to my horns (mainly for the sub) so I may need 3 volume controls, and I'm definitely not buying another two pairs of the S&Bs. Note my system is balanced throughout.

I find it difficult to accurately describe in writing so another person readily understands the differences as i percieve them, so I wont evem bother. Within the context of my system, they are fine sounding, and excellent value, all considered. I also disagree with your assertion that iron in the signal path is always bad. I find almost every capacitor I've ever heard is more obnoxiously coloured than a good piece of iron, whenever I've done the comparisons.

TVCs are a bit too hyped for my taste too.

[Steve Eddy]

Originally posted by analog_sa
The concept of TVC will become genuinely interesting when someone manages to get sufficient performance combined with an airgap. Even if it's a 5mA airgap.

Performance and airgap are rather mutually exclusive, no?

Any air gap will only decrease your coupling and increase distortion. Largely odd order distortion. Not that a little distortion is necessarily bad, but I assume by "performance" you're infering objective performance.

Instead of an airgap, why not run a few mills through the secondary? This would cancel the effects of the current in the primary.

se

[analog_sa]

Brett

Sorry if i wasn't clear. I don't find iron at all objectionable as i use IC and O/P transformers and plate chokes. So far i haven't been able to find a MC step-up iron that i like but that's another issue.
You're lucky not to be so compulsively obsessed with comparisons as i am Just curious: do you like PIO caps? I find the 102 strangely reminiscent of a good PIO - it gives tone a priority but certainly closes the window a bit. I can see that long term life with those can also cure my cable neurosis as a lot of these differences are now masked. Very likely my hearing is also not what it used to be and i have a strong reaction to devices limiting it even further


SE

I was never aware that airgaps cause distortion. In fact i thought they linearised the core inductance. Of course my desire for an airgap has a lot to do with that unnecessary coupling cap. Deep in my memory is buried some objection to the primary/secondary flux cancellation idea, but if i don't remember it i'll probably try it. Thanks.


peter