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Poor man's transformer volume control?

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#41
pooge said:
But a transformer will break ground loops, and easily allow for a mix of single-ended and balanced inputs and single-ended or balanced output (the best feature, IMO), with no additional conversion circuitry.
Click to expand...

I think I'd disagree about the "best feature". The best feature is the improved sound quality over a resistive volume control. The autoformer volume control has this feature.
 
#42
The S&B 102 mk 2 has the reputation of being less exhalted than the 102 mk 3 so I was probably not starting with the best TVC in the world......but, when I wired it as an ATVC ( or AVC ) the improvements were considerable - more speed, detail, bass, treble & dynamics....🙂

I am making a 102 mk 3 pre-amp for someone else now so I can do a comparison and I will post my findings.

For now, I wanted to make the point that at least in some cases AVC mode can sound better so the disadvantage of losing ground isolation is only one consideration.

mike
 
#43
Konnichiwa,

Steve Eddy said:
I seem to recall something about wanting to keep the primary a single winding rather than two.
Click to expand...

Absolutely. The Bifilar wound TX-102 had a single primary, WITH A 50% Tap. The current MKIII is back to dual windings IIRC.

But any version of the TX-102 has had the +6db passive gain option.

Sayonara
 
#44
another poorman's MVC

Hi,
My friend have customarily made a few magnetic Volume Control. Due to the budget he didn't made a case as S&B to shield it. The lamitation is Nickel.

The transformers are marching in :
An externally hosted image should be here but it was not working when we last tested it.


Look closer:
An externally hosted image should be here but it was not working when we last tested it.


After receiving the trans and selector, I spent about total 8 hrs to assemble them in my old passive chassis. The result is excellent!

Octopus!!
sw01.jpg


a closer look:
sw02.jpg


The MVC with indication:
trans01.jpg


These two are matched pair:
trans02.jpg

trans03.jpg


Upper look:
trans04.jpg


Mounting selector on chassis:
swwiring.jpg


Hard-wired with heat-shrinked silver bared wire the selector and MVC:
wiring.jpg


The MVC with selector
wiring02.jpg


Whole view:
finish.jpg


The music thru the MVC is shockingly with feeling and fidelity!

cheers

Coffin
 
#57
Kuei Yang Wang said:

If you have a very low source impedance and you use very few turns you can quite easily wind your own with good results, be it an autoformer or a true transformer (place the tapped secondary between two layers of 1/2 primary each), however the nominal impedance will be low, usually in the region of a few 100 Ohm and level handeling tends to be shitty.
Click to expand...

What if I need more than one layer ?

500 turns primary : 1000 secondary

not more than 15 ohm dc : 60 ohm dc could become big.
 
#60
Hi everyone, I'd love to get this thread back to life as I'm thinking about upgrading my Audio Note L2 Phono kit with a transformer volume control, like the mentioned Sowter 9335 or S&B TX102. I'm wondering if this would be a simple exchange job from the 100K attenuator I currently use to the transformers on a switch.
The schematic of the preamp can be found on the last sheets of this document: Manual

Thank you very much!
 
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