Help me improve this amp

[anotherjim]

I don't think you will fry this particular chip. It lowers volume if it gets too hot. It can get very hot, 150c according to the data. The data is assuming a clean sine wave signal, which a guitar amp can't always expect with distortion pedals around.

As I said, there is a power rating given with a 16ohm speaker on 6v supply. Amp power is approximately 0.7 (Vsq/R). 0.7 * 36/16 = 1.5W. Clearly, that's more power than the datasheet claims, so it can't be able to swing the full 6v -  probably more like 5v. There is no spec for the output voltage swing that I can find.

Let's suppose at 9v supply it can do 8v swing and with a 4ohm load...
0.7x(64/4)=11W! It cannot possibly produce that much power so either...
Your power supply is actually giving less than 9v.
Your speakers are actually higher resistance than 4ohm.
The chip is already thermal limiting and lowering the volume to protect itself as the datasheet promises.

[taviii]

Let's suppose at 9v supply it can do 8v swing and with a 4ohm load...
0.7x(64/4)=11W! It cannot possibly produce that much power so either...

let me know if i got this right, the ic being 1W would never reproduce any input surpasing that?
so if i wire the speaker in series to get 16ohm i will get - 0.7x(64/16)=2.8W?
will it be better?

The chip is already thermal limiting and lowering the volume to protect itself as the datasheet promises.

this could be it

The maximum gain of the amplifier is fixed at 35.5 dB. The
DC volume control stage has a logarithmic control
characteristic.
The total gain can be controlled from 35.5 dB to −44 dB. If
the DC volume control voltage is below 0.3 V, the device
switches to the mute mode.

i extracted this from the chip datasheet,maybea fuzz produces more gain than what the amp can handle?

[anotherjim]

You can use the volume to lower the gain though. So at some range of control, the amp is clean and under the temperature limit. Wiring for 16ohm might still give the same maximum volume but without the thermal limiting.

[taviii]

Wiring for 16ohm might still give the same maximum volume but without the thermal limiting.

Thats correct, ive almost finished it, wiring the speakers in series was a great change.
I have also moved the volume pot to the output, and replaced the 470nf cap for a 100nf ceramic.

I'm really happy with how it performs.

[taviii]

Wiring for 16ohm might still give the same maximum volume but without the thermal limiting.

Thats correct, ive almost finished it, wiring the speakers in series was a great change.
I have also moved the volume pot to the output, and replaced the 470nf cap for a 100nf ceramic.

I'm really happy with how it performs.

I've also learned that the open/closed cabinet back has quite an effect on the tone.

[taviii]

Update. Been using this amp quite a bit and I'm really enjoying it, but i would like to know if there is a way to add a Bluetooth module to it so i can use it to play music from my celphone as a portable speaker.
The amp is currently running on a 12v 2ah lithium battery and it gives many hours of playing.




I understand the signal would be stereo and the amp is mono, is there a way this could work?
Or would i need to build a stereo amp .

Also this modules work with 5v so i would need a dc dc step-down to run it

[11-90-an]

Well you can do some rewiring to make your amp stereo (as you have 2 speakers)
But if you don't want to bother, that's fine. You can just put 1k resistors on both left and right inputs and connect them afterwards.