[Electronics] Potentiometer Ohm range for audio limiter

[sorex]

Hello,

This goes out to the electronic guys/girls.

A few years ago I placed a small amplifier right after my ADSL based digital tv receiver.
The purpose is to have the radio playing without the need to have my TV on.

While this works fine there is still an issue I want to get rid off.

The sound volume coming from the "TV box" is too loud and can't be controlled by the remote.
So I have to adjust the volume somewhere between 0-5% if it ain't less than that.
The problem is that the beginning of that potentio knob is so sensitive that it is hard to control
and sometimes a channel that shuts down or louder than the other.

When you go beyond that point it's flawless in control but then it's way to loud to keep it like that.

Now I asked the electrician at work who used to be an electronics engineer for airplaines what could be done about it.

He mentioned some bridge with a few resistors or even better for less skilled persons a stereo potentio meter instead of 2 seperate ones.

Now I wonder what kind of Ohm range I should pick for this.

according to the link below I could pick from 1K to 500K.

https://nl.aliexpress.com/item/3294...chweb0_0,searchweb201602_3,searchweb201603_53


1K might be enough but gives me a very small adjust range.
500K might be overkill and leading to too less sound volume and might be the opposite of what I have now with my knob.
Should I just go for something inbetween knowing that it's still adjustable on both ends?


Can anyone give me some hints?

 

[Cableguy]

The Potenciometer value will "set" your variation range...

Imagine you use a 1K pot, your "steps" would then be of 0 to 1000 to go from 0 to 100%, giving you a resolution of 0,1%, but would be also very sensible and hard to find the sweet spot you want.
if you use a 10K pot, your steps go from 0 to 10 000 to go from 0 to 100%, giving you a resolution of 0,01%... and so on...
The trick is to find a pot you feel confortable using...
Stereo pots are expensive, so buying a couple may not be doable, but you can buy a few "normal" pots, 1K, 500K, 1M, and try them out on one chanel… then buy the stereo one of that values.

 

[sorex]

Hey Cableguy,

less than €1 including p&p can't be called expensive

The problem is that I don't know if 1K is flexible enough already.
on the other hand 10K might be better and if it's too much the amp just has to be put higher
and if this means at 20% we are way beyond that problematic part in the beginning of the pot and this is just what I want to achieve.

I believe the bridge my colleague drew was with 5K & 10K resistors. maybe I'll just go for the 10K one and see what that gives.

 

[Cableguy]

If you have a multimeter at hand, you can try to set the existing potentiometer to your sweet spot, and then mesure the set value from the middle leg the ones on he sides, and take the higher value as reference… it should do the trick.

 

[sorex]

indeed, if I can reach it easily.

thanks for the hint!

 

[sorex]

the 10K pot arrived today.

after some soldering and wiring it was time to turn on the amplifier.

first I didn't hear anything but it was the pot that was completely at 10KOhm.

after some knob tweaking of the pot I had some sound. now the sound is reasonable with the amp around 15% and past the problematic zone

I notice that the pot knob needs to be around 70-100% open to get sound.

When I connected the wires I noticed the notification about 8 Ohm so in theory a pot of 1K Ohm
would've giving me a bit better control but hey my problem is gone so me happy

 

[agraham]

Have you got a linear or a log pot? Audio normally uses log pots as the human response to sound is not linear.

 

[Cableguy]

Have you got a linear or a log pot? Audio normally uses log pots as the human response to sound is not linear.

Most Pots are linear...

 

[agraham]

Not in my (quite extensive) experience for audio work. Farnell, a components supply company here, list 57 audio log potentiometers, though surprisingly no stereo ones now though they used to have them. There are plentiful mono and stereo linear and log potentiometers offered on eBay here.

 

[sorex]

yes, it's a linear stereo pot. I got it from aliexpress with screws and knob for like half a euro incl. shipping (was 0.2 without shipping or so)

 

[agraham]

An audio log pot will be less 'sudden' at the lower volume settings. and should give a more perceptively linear increase in sound level.as the volume is increased.

 

[f0raster0]

guys ahah
then Can this be the next step:

B4x App < - > Bluetooth-uC + digital Pot

ahah
(don't know Audio Pot)