P50 Stepped attenuators

[karatestu]

Deos a stepped attenuator have a single ohmic value. Wouldn't it change as you stepped the volume from resistor to resistor.

Yes. I think 10k would be the least resistance or the volume would be at max all the time.

The resistor in series with the signal is the value given for the attenuator (10k, 20k, 50k etc). The volume is changed by changing the value of the resistor to 0V. That is how my volume setting resistors are wired up - 10k in series with the signal and 768R to 0V . There are other ways of doing it but that copies the way the hifi collective ones are wired up. To increase volume the resistor value to 0V gets larger.

Here is a diagram of the situation i have from Dac to input stage of the power amp(s).

[Alfi]

Nice explanation there Stu.

Would that 10k be the shunt resistor?

Cheers.

Best wishes.
Alfi.

[karatestu]

Nice explanation there Stu.

Would that 10k be the shunt resistor?

Cheers.

Best wishes.
Alfi.

The resistor in series with the signal (10k) is called the "series resistor". The resistor to 0V is called the "shunt resistor".

[Alfi]

Thanks m8!

Alfi.

[_D_S_J_R_]

I always thought carbons were 'noisier' and also inclined to drift. Metal films are usually much closer tolerance these days (1% or less) and that's what NVA amp boards are made using. Still, it's fun to try different things.

[Ali Tait]

True in the old days, but the modern carbon films measure as well as the metals now and don’t drift.

Comes down to personal taste I suppose, but I built a steppper with metals and found it setting my fillings off on occasion. Couldn’t live with it so swapped to carbons. Much better to my ears.

[_D_S_J_R_]

Thanks for the info Ali :D

[Ali Tait]

Some blurb here, specs show 2% matching-

https://www.hificollective.co.uk/compon ... stors.html

[karatestu]

Some blurb here, specs show 2% matching-

https://www.hificollective.co.uk/compon ... stors.html

Might give them a go. Certainly a lot easier on the wallet than the charcroft bulk foils that i was also thinking of.

[Hannes-Gregor]

I only have two of the Charcrofts as load resistors, so still affordable. The rest is Takman metal.