S&B TX102 and preamplier stages

[KT]

Did you guys see the glowing review of the TX102 in Hi-Fi News and Record Review?

Given how great the TX102s sound just as a stand-alone attenuator, I'm wondering whether this renders the active preamplifier superfluous. Has anybody tried TX102 both as a stand-alone attenuator AND as the volume control for an active preamplifier? If so, which did you prefer?

I understand that one would need preamplification for vinyl and to drive amplifiers with very low sensitivity. But for sources such as CD and SACD, does the TX102 perform well enough that you wouldn't want to use a preamplification stage after it?

This is related to the resistive attenuator vs. active preamp question. I myself prefer using an active preamplifier over a stand-alone resistive attenuator because I find that it fleshes the sound out and provides a richness and body that the attenuator alone does not provide. This is with sources with sufficient gain.

Is the TX102 a different enough creature that this is not the case?

Love to hear some opinions.

Thanks,
KT

 

[KevinTams]

I have an Alps blue pot connected to one input and output phono pair of connectors (no switching) in a small housing. The interconnects are DIY specially made for length, i.e just long enough.

I compared this directly, to the latest £800 Quad valve amp and a meridian pre amp and preferred the passive for clarity and transparency. No difference in the bass except possibly a tad more musicality in the passive but nothing exceptional.

Have you seen the WIKI for S&B TX102's, if you fancy a pair get your name down quick

Kev

 

[ThorstenL]

Konnichiwa,

Given how great the TX102s sound just as a stand-alone attenuator, I'm wondering whether this renders the active preamplifier superfluous. Has anybody tried TX102 both as a stand-alone attenuator AND as the volume control for an active preamplifier? If so, which did you prefer?

I prefer to avoid the added colorations from an unnecesary active stage, I have tried both options and various resistive passive preamps, buffered and unbuffered.

for sources such as CD and SACD, does the TX102 perform well enough that you wouldn't want to use a preamplification stage after it?

Absolutely.

This is related to the resistive attenuator vs. active preamp question. I myself prefer using an active preamplifier over a stand-alone resistive attenuator because I find that it fleshes the sound out and provides a richness and body that the attenuator alone does not provide. This is with sources with sufficient gain.

Same here.

Is the TX102 a different enough creature that this is not the case?

Yes.

Sayonara

 

[Gregm]

Further on the subject I saw a pic of the belly (inside) of Kuei's TX102 volume control at Ardumann's site:

Kuei, you have a smal circuit connected at the output rca's but I can't figure out the "connection" from the photo.

Would you be willing to give a few hints?
Cheers

 

[ThorstenL]

Konnichiwa,

Kuei, you have a smal circuit connected at the output rca's

No, I have NOT. All I have is a switch that connects either RCA Ring or XLR Pin1 to the main Preamp ground, or floats both.

On the Input Connectors there are Series RC terminators (2n2 & 51R) for RF to preamp ground from the shield termination (Ring on RCA, Pin1 on XLR) the input is otherwise treated floating, with the exception of one RCA input (for TV sound) which has a 100 Ohm to preamp ground selected by a spare contact of the input relais as otherwise things hummed a little too much.

The thing that you should be asking about is the RC circuit on the switch. This was a (sucessfull) attempt to stop the MKI TX-102 from having as large an untrasonic peak at low volume settings as it showed. It was simply an RC Circuit across the top of the secondary (0db Tap) and the Wiper of the switch, which allowed the unconnected windings to be terminated corretcly.

From the MK II TX-102 these where not neccesary to stop ultrasonic peaks and even on the MK I I preferred the sound without them.

Sayonara

 

[andyjevans]

Hi there, Thorsten - is this TVC unbalanced or can it be used balanced in and out? If it can be used balanced, is there a need for a coupling capacitor into it if the signal comes from, say, a diff pair? I'm not sure the answer I got from S&B is correct - they seemed to imply you needed a coupling cap in all cases. Is this true, and if so why exactly? Andy

 

[ThorstenL]

Konnichiwa,

Hi there, Thorsten - is this TVC unbalanced or can it be used balanced in and out?

A TTVC (True Transformer Volume Control - as opposed to AVC's often called TVC's) is a transformer. A competently designed symmetrical audio line-level transformer is just that. The input and output is "differential floating". The concept of "balanced" or "unbalanced" does not exist.

It will pick up the signal between the two ends of the primary coil and output a signal between the two (selected) ends of the secondary coil. The one possible snag is a bifilar wound transformer (eg TX-102 MK II) which can cause in certain conditions problems with the balance at high frequencies.

If it can be used balanced, is there a need for a coupling capacitor into it if the signal comes from, say, a diff pair?

The signal must be free of DC. You can ahieve this easiest and safest with a coupling capacitor. Using other methodes is of your perogative, but remember, NO (material) DC CURRENT in the primary or secondary.

Sayonara

 

[Gregm]

Thanks, Kuei