transformer volume control (TVC)

[louie 3]

signal to output

Well, it would, if the output were, indeed, the output....but in this case the input was the output, and the output was the input.

Oh...the left and right are backwards, also...left is right, right is left.

I cobbled together a switch box with an Elna selector switch, an old preamp chassis and some wire and plugs.

The thing is so transparent I can clearly hear the difference between a direct input and the input through the switch box (about 1 db signal loss?), and I used three different types of wire for the three different positions on the switch, and I can hear the difference between the three types of wire.

I thought I had heard transparency...nope, not like this.

Thanks for helping me help it through folks.

Louie

 

[Robert F]

Analog,

The trouble with buying the tx's in their "raw" state is that you are likely getting a can with about 30 wires exiting it either with different colour insulation or coloured heatshrink. So it is unlikely the primary and secondary wires are marked as input and output respectively. Mpore confusing still are those TVC's with dual primaries offering a +6db option. So you have to work out that you wire the primaries in series for no "gain"or in parallel for +6db. Good instructions are paramount, tho' you can work out the taps on the secondary by measuring their respective DC resistance, but this is rather labour intensive.

Rob.

 

[Johnloudb]

Transformer Core

I'm designing/building a transformer volume control, and need some advice on the type of core material is best. Here is a link to the different toroid cores I'm considering:

http://www.surplussales.com/Inductors/FerToro/FerToro-3.html

I'm thinking that a ferrite core with low loss and high permativity would be good, but there seems to be many types to choose from with different applications. Would a powdered iron core be preferable? Or does it matter?

Thanks!

 

[tiefbassuebertr]

I'm designing/building a transformer volume control, and need some advice on the type of core material is best. Here is a link to the different toroid cores I'm considering:

Toroids - Ferrite & Powder

I'm thinking that a ferrite core with low loss and high permativity would be good, but there seems to be many types to choose from with different applications. Would a powdered iron core be preferable? Or does it matter?

Thanks!

I want to know this, too.
Additional I want to know if there are TVC versions, which are to prefer for long leads resp. long wires between 5 and 10 meters to the power amp
(maybe with voltage gain below unity gain, i. e. between 0,2 to 0,8).
Thank you very much for advices.
on post #26 under
passive preamp
I have listed several passive preamps. Maybe some few of them are good for such applications.
And here are an overview on TVC's
Tube and Passive Preamps-Auto Transformers for Attenuators/Volume Control - Overview