Hi all.
I used the (1) for Audio Amplifier from ESP32 RADIO. The minimum volume is kind of too high, how to do with this?
and is it OK to replace the green potentiometer by a smaller one like (2)?



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No. Leave the green pot where it is. Put a voltage divider on the inputs to the amplifier.

 

Something is wrong. The minimum volume should be inaudible. Is there possibly a bad solder connection?

 

The circuit uses a dual 10K volume control, so I would attenuate the inputs with two 10 K presets , then you can adjust the level to suit.

The inputs are grounded on the minimum setting, so maybe it's wired wrong.

 

I am going to guess that the grounded side of the pot is not connected.

 

The circuit uses a dual 10K volume control, so I would attenuate the inputs with two 10 K presets , then you can adjust the level to suit.

The inputs are grounded on the minimum setting, so maybe it's wired wrong.

View attachment 324547

I used TEA5767 + Amp and ref. circuit:
https://www.hackster.io/mircemk/linear-scale-5767-fm-radio-on-ili9341-tft-display-e45fb4

I'll test inputs with two 10 K presets.

 

Something is wrong. The minimum volume should be inaudible. Is there possibly a bad solder connection?

I'll check and test again.

 

No. Leave the green pot where it is. Put a voltage divider on the inputs to the amplifier.

I used 4.7K+4.7K made it.
Thanks.

The green pot is kind of too large for my design.
I saw a LM386 amp used normal pot?

 

The green pot is kind of too large for my design.
I saw a LM386 amp used normal pot?

You can use a physically smaller pot but, since the PAM8403 is a stereo amp, you need a dual pot.
They are all "normal" pots.

The LM386 is a mono amp so needs only a single-gang pot.

 

The simple and safe way to reduce the minimum output level requires TWO resistors per channel. At the tree input connection points that I see in post #1, connect a 10K ohm resistor between the input and the center "G" point. Then, connect another 10K ohm resistor between the input point and your signal source. That should provide a good reduction.

As for a suitable replacement control, you need to show us the underside of the PCB.
A second option is to add an external variable control that is the size you choose , and then use that control to adjust the output level.

 

The simple and safe way to reduce the minimum output level requires TWO resistors per channel. At the tree input connection points that I see in post #1, connect a 10K ohm resistor between the input and the center "G" point. Then, connect another 10K ohm resistor between the input point and your signal source. That should provide a good reduction.

As for a suitable replacement control, you need to show us the underside of the PCB.
A second option is to add an external variable control that is the size you choose , and then use that control to adjust the output level.

The question is why the original control is malfunctioning.

 

The question is why the original control is malfunctioning.

First, for some applications, a volume control that will reduce to zero is a very poor choice. An alarm announcement system is an example of that. The communications system in a police car is another example. so is a baby monitor receiver.
So the ability to reduce the level may be very intentionally limited.
I asked for a view of the solder side of the PCB because that is where we could see if there were series resistors added at the "bottom" of the gain control. That would be the common way to set the minimum level.

One more thing: comparing the variable pot installed on the circuit board with the proposed replacement, do you see any possible way that could be done without it being a really "cobbled" job???

 

The datasheet for the PAM8403 amplifier says when it is powered from 5.0V and drives 4 ohm speakers its output is 3W per channel when it is clipping like crazy with 10% distortion.
Its output is 2W per channel into 4 ohm speakers when it is hifi with no clipping distortion and is 1.2W per channel into 8 ohm speakers.

I agree that your volume control or its wiring is defective. It should produce no output signal when turned down.

 

The datasheet for the PAM8403 amplifier says when it is powered from 5.0V and drives 4 ohm speakers its output is 3W per channel when it is clipping like crazy with 10% distortion.
Its output is 2W per channel into 4 ohm speakers when it is hifi with no clipping distortion and is 1.2W per channel into 8 ohm speakers.

I agree that your volume control or its wiring is defective. It should produce no output signal when turned down.

If you choose to reduce the output to zero, SWITCH IT OFF!!!
Either sounds are to be heard or switched off. Playing sound to "drown out the silence" is often rather irksome to those who find the really awful, horrible junk passed off as "beautiful music" because it includes violins really bothersome.
The TS has never mentioned how loud the minimum level actually is, and the fact is that not everybody has perfect hearing, able to hear a mouses heartbeat from ten feet away, thru a closed door.
And still, the amplifier maybe designed to produce minimum level.

 

The LM386 is a mono amp so needs only a single-gang pot.

Thanks.
learned it.

 

you need to show us the underside of the PCB.

Thanks.
I just put resistors on breadboard for now:

 

The question is why the original control is malfunctioning.

do you mean the "original" is the TEA5767 Module, which don't have a control, just output signal.

 

Thanks.
learned it.

The amplifier in post #1 uses a 16 pin IC, which is certainly NOT an LM386. Also, the volume control pot is not even slightly similar in appearance to the proposed replacement.
Besides that, at least in battery powered systems, turning the volume down to inaudible is a certain way to waste battery power. So not being able to leave it powered but not delivering any useful sound is not a malfunction at all.

 

I asked for a view of the solder side of the PCB

Thanks.

and ref.:
https://www.aliexpress.us/item/3256803303005421.html?src=google&gatewayAdapt=glo2usa

do you see any possible way that

I am not familiar it well.

 

when it is clipping like crazy with 10% distortion.

Its true that any lower than original input volume which is kind of too high got bad noise till turned off.

It should produce no output signal when turned down

There is no output till turned off. I'll try other speakers.