Is there such a thing as a stereo trimpot?

Thread Starter

djryanash

Joined Feb 1, 2017
6
Hi all,

This is my first time here.

I want to add a PCB trimpot to an audio input design I'm doing. But I don't want to trim each side - left and right - individually. I want to trim both left and right together with 1 trimpot. I have only and wasn't able to find 2-gang (or 2-pole) trimpot. What is the usual solution to this situation? I'm sure it's been done before.

How can I use 1 trimpot to trim left and right without making the signal mono?
 

Alec_t

Joined Sep 17, 2013
12,249
Welcome to AAC.
You can get SMD trimmers which are adjustable from both sides. Perhaps you could find a way to fix two together so that a single shaft would enable both to be adjusted at the same time.
 

dl324

Joined Mar 30, 2015
13,293
Welcome to AAC!
I want to trim both left and right together with 1 trimpot. I have only and wasn't able to find 2-gang (or 2-pole) trimpot. What is the usual solution to this situation?
For audio, you probably want audio taper because our hearing is logarithmic.

Mouser lists over 400 items for dual audio pot. Some mechanical, some IC's.
 

ian field

Joined Oct 27, 2012
6,539
Hi all,

This is my first time here.

I want to add a PCB trimpot to an audio input design I'm doing. But I don't want to trim each side - left and right - individually. I want to trim both left and right together with 1 trimpot. I have only and wasn't able to find 2-gang (or 2-pole) trimpot. What is the usual solution to this situation? I'm sure it's been done before.

How can I use 1 trimpot to trim left and right without making the signal mono?
There were stackable trimpots, but they're much harder to find nowadays.

Most manufacturers are designing trimpots out of their products, the settings are now a code in flash memory fed to a DAC.

With less incentive to stock them - many suppliers don't.
 

kubeek

Joined Sep 20, 2005
5,763
Depends on what you want to trim, but you could possibly ground the viper and use the two ends to balance out the L and R for example.
 

ian field

Joined Oct 27, 2012
6,539
Depends on what you want to trim, but you could possibly ground the viper and use the two ends to balance out the L and R for example.
Any resistance at all from the track through the wiper to GND introduces crosstalk - but it is the usual standard for the balance control on most stereos.
 

MrAl

Joined Jun 17, 2014
8,500
Hi,

Some good ideas here.

I would have to ask, what is this going to be used for and why is a dual trimmer pot so important?
In other words, what is holding you back from using two trimmers and doing each channel separately.
Slight differences in channels could then also be compensated for instead of being stuck with doing both at once.
 

Thread Starter

djryanash

Joined Feb 1, 2017
6
Hi,

Some good ideas here.

I would have to ask, what is this going to be used for and why is a dual trimmer pot so important?
In other words, what is holding you back from using two trimmers and doing each channel separately.
Slight differences in channels could then also be compensated for instead of being stuck with doing both at once.
It's for "ease-of-use". When designing for the end-user, every additional variable exponentially increases the possibility of something going wrong.

I think maybe going the IC route would be better. I mean, two opamps in a single package with gain pins (controlled by a single trimpot) similar to the LM386 - but with two opamps and better THD stats.

I'd still like to do it without the opamp - to save on costs.
 

GopherT

Joined Nov 23, 2012
8,012
It's for "ease-of-use". When designing for the end-user, every additional variable exponentially increases the possibility of something going wrong.

I think maybe going the IC route would be better. I mean, two opamps in a single package with gain pins (controlled by a single trimpot) similar to the LM386 - but with two opamps and better THD stats.

I'd still like to do it without the opamp - to save on costs.
Op amps can be cheaper than trim pots. Depends on your specs (for both parts).
 

kubeek

Joined Sep 20, 2005
5,763
It's for "ease-of-use". When designing for the end-user, every additional variable exponentially increases the possibility of something going wrong.

I think maybe going the IC route would be better. I mean, two opamps in a single package with gain pins (controlled by a single trimpot) similar to the LM386 - but with two opamps and better THD stats.

I'd still like to do it without the opamp - to save on costs.
I guess this is a thing that is set once and then forgotten, and the gain will be the same for both channels? You could simply use a bunch of jumpers that set the gain, three jumpers per channel can give you 8 different gain levels.
 

GopherT

Joined Nov 23, 2012
8,012
But how do you change the gain of an op amp without a pot? :confused:
I should have said, a dual op amp is cheaper than a trim pot.

He'd either need one dual op amp and one trim pot or two trim pots (or an apparently rare dual trim pot (that may be the most expensive option based on rarity if it even exists).

Although I am not immediately visualizing how a two op amps amd one pot will control his volume without a schematic.
 
Last edited:

ian field

Joined Oct 27, 2012
6,539
It's for "ease-of-use". When designing for the end-user, every additional variable exponentially increases the possibility of something going wrong.

I think maybe going the IC route would be better. I mean, two opamps in a single package with gain pins (controlled by a single trimpot) similar to the LM386 - but with two opamps and better THD stats.

I'd still like to do it without the opamp - to save on costs.
Trimmers may not be any cheaper than op-amps - I think you can still get variable gain amplifiers, the LM13700 may be an option.
 
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