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Potentiometer choices.

Posted: Wed Nov 25, 2015 1:56 pm
by Abminor
I have to replace the pot on my passive amplifier as I recycled it from old equipment and despite cleaning, it is scratchy. Does anyone have thoughts or advice on the following options?

1. Buy a good quality replacement from Radionics e.g. http://ie.rs-online.com/web/p/potentiometers/2369604/

2. Make a stepped attenuator soldering resistors on to an attenuator switch such as http://www.hificollective.co.uk/switche ... lated.html . What is the sonic advantage? I'm not sure I buy the idea that different resistors have different sonic charms and this approach is somehow better than the slider in the ALPS pot above. (It's doubtless more satisfying for the hobbyist in me to work out the correct resistor values and solder it up - but will it be better?)

3. One problem with either the above is that there is no remote control. If going down the discrete resistor path, I'm tempted by the idea of interfacing an arduino with some relays that switch appropriate resistors in and out.

4. But rather than relays, what about this beastie at radionics: http://ie.rs-online.com/web/p/digital-p ... s/5405270/ , a digital pot where the 'relay switching' is presumably done by semiconductors on the chip. My question here is to the quality of this approach and whether it presents a genuine resistance on the output pins without associated noise from the switching electronics. Spec claim low distortion, so is this the holy grail of a cheap pot that I can quite easily make into a remote using an arduino?

Any thoughts or experiences of this are most welcome.

Re: Potentiometer choices.

Posted: Wed Nov 25, 2015 2:29 pm
by sbgk
For best quality, work out the volume you most frequently use and select a resistor that gives that volume.

Re: Potentiometer choices.

Posted: Wed Nov 25, 2015 2:43 pm
by nige2000
I'd imagine you could have three or four good resistor's you could plug in the front to get the desired volume
I'd imagine most people listen within +/-10db
Resistors do sound different

Re: Potentiometer choices.

Posted: Wed Nov 25, 2015 6:07 pm
by randytsuch
A volume control project I've looked at uses the Muse 72320 chip for volume control. It's supposed to be very transparent, Pass uses it in their really expensive preamp.

Over in Europe, this place sells boards with it.

http://www.akouo.at/serie-45-modulsystem.html

At a minimum, you need a 72320 board, a power supply and a controller.

Since my dac has built in volume control, I'll probably use that instead of the 72320, although one of these days I'd like to try the 72320 and see how it works. There is a place over here that sells a board I'd like to try.

Randy

Re: Potentiometer choices.

Posted: Tue Dec 01, 2015 9:48 pm
by rickmcinnis
Consider using Dave Slagle's autoformer volume control. http://www.intactaudio.com/atten.html - I am using the one that is ready to use. Too lazy to wire it up to a switch. Not enough time ...

Easy to install. You will have a variety of levels with very low distortion.

At the highest levels there is a possibility of the loss some high frequency output. I do not notice it but Dave said it is possible.

Someone found the on-board volume control has problems, even with the new firmware.

I am stuck with it until I get a line stage built.

I use the autoformer as an attenuator on the output of my phono stage.

I figure this is something I will never discard. It is something you can use for the rest of your audio life.