input potentiometers

[infobot]

What is the difference sonically between using different value input potentiometers ?


I have an LM3886 gclone, have to get a 100k ohm stereo pot for another amp, it got me wondering.

[AndrewT]

Hi,
the pot will interfere with the operation of the filters and the input offset of any amplifier tacked on after the pot.

The Pot and what follows must be designed to operate as required.

The pot also interacts with the source component and this too becomes part of the design exercise.

[Vautrin]

Peter Daniel's comparison of potentiometers from several manufacturers was an eye-opener for me:

So I did try all those different potentiometers


David in SW FL

[YFW]

The volume control VR shoud match the impedance.I think 10K A type is your choice.

[infobot]

Thanks Andrew and that sounds good to be aware of besides too. Yup link very helpful to me too. Think I'll try the 10K soon.

Got curious - am a gainclone newbie, didn't know if folks gravitated toward various potschoices. Like if were softer vs more analytical, or if some would favor certain pots to better match components, speakers, etc.



Got a 50K ALPS coming (Parts Connection.com didn't have 25K) with a 100K for another amp- very nearly got the 10K sounded good but got last minute unsure. Peter's and Brian's kits list 25 and 50K, thought start there then eye upgrades.

Also am curious to hear ALPS and NOBLEs. I'll try a 10K when I get a long enough parts list to make up a decent size order.


PS
Additional impressions (varied always useful), posts always welcome too certainly.

[sharpi31]

It's best to pick a pot/attenuator with an impedance below the input impedance of the amp. My non-inverted amps have around 20Kohm input impedances, so the best choice is a 10Kohm pot/attenuator.

After trying many pots (Alps, PEC etc.) I've settled on cheap ebay stepped attenuators. Far better sounding (to me) than any pot and often cheaper too:

10Kohm Dale stepped attenuator

There are also smd attenuators on ebay from time to time - these are my first choice.

[AndrewT]

I prefer to see an Zin:Rs ratio of around 20times.
But certainly >=10times.
I consider 10k pot for Zin=50k, 5k pot for Zin=20k and 2k pot for Zin=10k.
Provided, that the source can properly drive these low resistance pots.

[infobot]

How about tweaks ?

I mean off the top of your head, common quick fix types - not so much like calculating and fine tuning a stepped attenuator.

Like if once you've got it calculated is there a "fiddlin' " range around that value ? Swap up or down a bit to alter the sonic character ?

Or is there no such animal best to get it as close to carrect as possible ?

Don't get me wrong, the above info great, helped. Just as I'd said getting a 100K replacement for another amp go me to wondering.

[infobot]

Got the 50K yesterday, sounds pretty good. Little constriction, very slight (had no pot before). I'll try the 10K soon.

See, the past couple of years I built a bunch of single coil pickguards for a guitar. 250K was standard value for single coil pickups. Using 500K brightened up the sound, 250K or less emphasized the bass some.

Didn't know if gainclones had similar tweaks. I realize it's not the same as guitar pickups and am using the gainclone for stereo, not instruments. Again the replies were perfect, fine for what I asked and are helping me better be able to choose pots. Just reclarifying if that sounded weird, everyone's going for closest matching.

Think the pickguard projects and other component tweaks matching's got me to wondering if there were similar things tried with gainclones.