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  #1  
Old 02-21-2009, 07:12 PM
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My new passive preamp: S&B TX-102 transformer volume control

doucanoe asked for pictures, so I thought a thread might be in order. This is new to me, but not new. It's a passive preamplifier, a transformer volume control built around a pair of Stevens and Billington TX-102 transformers. Single input, single output with a mute switch.

The previous owner bought it new, purchased from K&K Audio. They built it, and they certainly did a nice job!

That's a Seiden switch. High end Vampire RCAs. Check out the nice knob, too!

How does it sound? Pretty phenomenal, I think.













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Old 02-21-2009, 07:53 PM
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Very nice work!
Where did you get the case?
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Old 02-21-2009, 08:05 PM
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Nice.

I assume you are giving it a test drive. In your pic you have two sources.

Where or how do you think you will use it?

Someday in my hifi journey I expect to give a passive preamp a try.
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Old 02-21-2009, 09:17 PM
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Sweet, what does the double toggle on the back panel switch?
If it is only1 ea. In and Out? Thanks, they did a nice build, I like 'm clean
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Old 02-21-2009, 09:18 PM
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I'd say that it's beautiful!
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Old 02-21-2009, 10:18 PM
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Very cool and great photos. And I have no real understanding of a passive preamplifier or what it does.
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Old 02-21-2009, 10:23 PM
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Nifty!
I'm going to have to get over and hear it sometime soon. It will be interesting to compare with the Promitheus.

RC
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Old 02-22-2009, 05:03 AM
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Very nice. I've been curious about transformer-based volume controls - I'd be interested if you could elaborate on "phenomenal" as a description of the sound
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Old 02-23-2009, 10:04 PM
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I'm a pretty big fan of simple. I'll have to give one of those TVC's a try one of these days.
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Old 02-24-2009, 08:25 AM
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I admire this apparatus, and certainly the quality of workmanship. But I seriously question the nomenclature.

Could it perhaps be called a volume control?

Passive Preamplifier seems a trifle oxymoronic....dontcha think....? Amplification is usually an active step. Transformers can indeed improve transmission, but amplify seems kinda extreme in describing what this inline variable attenuator does.... Mebbe I'm missing something here....

The English "language" is always intriguing to me....

Oh don't mind me; I know I'm a certified left-handed nut!

At any rate it must sound great.
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Old 02-24-2009, 09:33 AM
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Very nice Nate! Very simple. Is it going to be a problem that it only has one set of inputs?

TC
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Old 02-24-2009, 11:07 AM
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Very cool!
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Old 02-24-2009, 11:39 AM
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Quote:
Originally Posted by Old1625 View Post
I admire this apparatus, and certainly the quality of workmanship. But I seriously question the nomenclature.

Could it perhaps be called a volume control?

Passive Preamplifier seems a trifle oxymoronic....dontcha think....? Amplification is usually an active step. Transformers can indeed improve transmission, but amplify seems kinda extreme in describing what this inline variable attenuator does.... Mebbe I'm missing something here....

The English "language" is always intriguing to me....

Oh don't mind me; I know I'm a certified left-handed nut!

At any rate it must sound great.
It may help to think of "pre" as "before" amplifier.
Besides, the transformers have a 6 db boost option making them amplifiers.
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Old 02-24-2009, 01:08 PM
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Simple is where it's at. That looks like a high quality pre. I can't imagine it sounding bad!
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Old 02-24-2009, 02:44 PM
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Quote:
Originally Posted by rsfmotoman View Post
I assume you are giving it a test drive. In your pic you have two sources.

Where or how do you think you will use it?

Someday in my hifi journey I expect to give a passive preamp a try.
One of the first things I will do is rewire this thing to have two sets of inputs. I'll do away with the mute switch, I think, and make that a selector switch.

Quote:
Originally Posted by golana View Post
Sweet, what does the double toggle on the back panel switch?
If it is only1 ea. In and Out? Thanks, they did a nice build, I like 'm clean
The back panel switch selects between "connected" and "isolated" ground. So far I'm not hearing a difference between the two.

Quote:
Originally Posted by RichPA View Post
Very nice. I've been curious about transformer-based volume controls - I'd be interested if you could elaborate on "phenomenal" as a description of the sound
Rich, I've been a fan of simple potentiometer-based volume attenuators in my system. This one has similar characteristics, but the sound is somehow "fuller." There seems to be more detail at lower volumes especially, and resolution overall is excellent. I'm not very good at describing sound in general, but this is the best I've heard here.

I like the idea of as little as possible between me and the source. I know these things are quite system sensitive, having to do with input impedances and other things I don't understand. I hoped for a good fit based on my experience with other passives, and it has played out well so far.
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