Tiny power amp

[KindCanuck]

Build Rating

5.00 star(s)

I wanted something to be a backup to my tube amps, and something I can easily attach to my pedalboard.

Reading through the thread on the TPA3118 power amp board, I realized I could do it!

I found some tiny simple amplifier boards that run off 5v, so I can use the USB port on my Fender Engine room instead of a 9v port. I was doubtful of them, not thinking it would be enough to power my 8ohm v30.

Boy was I wrong! It is perfect, gets plenty loud, but I doubt that it would be good in a band context, but it is definitely loud enough for any solo practice. Exactly what I wanted!

I use a buffer based on the simple jfet buffer schematic, using a 2SK30 into a B1M pot for volume. I have a power switch with a filter cap and polarity protection feeding it all.

At first I had to enlarge the jack hole, as the odd nut was grounding out on the enclosure. I probably won’t use these style jacks again. I’ll get all plastic ones to eliminate that problem

 

[KindCanuck]

This is the board:

2pcs Robojax Audio Amplifier DIY Board Module XPT8871 Super Mini Digital Amplifier 5W (Mono, Single Speaker) https://a.co/d/63mzcAm

 

[Locrian99]

That is pretty cool. Do you have any issues with it getting dirty at higher volumes or does it stay fairly clean through out.

 

[Elijah-Baley]

Cool! Is this sounds clean is very cool.
Do you think we can use an internal board with a 7805 regulator voltage and supply it with a 9v psu?

 

[KindCanuck]

I haven’t played much with it yet, so I’ll get back to you once I dial it in. I have noticed distortion at higher levels, so I might try to set a max gain from the buffer circuit.

Cool! Is this sounds clean is very cool.
Do you think we can use an internal board with a 7805 regulator voltage and supply it with a 9v psu?

No, this board takes 3.3v or 5v only. I have some other more powerful boards that I’m going to use to build some more powerful amps. One takes 9v and the other is a TPA3110 board.

DKARDU 2 pcs OEP30W Mono Digital Power Amplifier Module DC 8-24V 36dB D Class Power Amplifier Board eplace TDA8932 with Single Head 3.5mm Audio Cable Single-Head DC Female Cable : Amazon.ca: Electronics

DKARDU 2 pcs OEP30W Mono Digital Power Amplifier Module DC 8-24V 36dB D Class Power Amplifier Board eplace TDA8932 with Single Head 3.5mm Audio Cable Single-Head DC Female Cable : Amazon.ca: Electronics

www.amazon.ca

And

https://www.amazon.ca/dp/B09F2XR9MN

I think for the next version, I would change the switch to a short bat and move it next to the power jack. This would allow more space for the pot and LED, so I can use more interesting knobs. I like the horizontal layout, I think it makes it clear that this pedal is different from others.

 

[Elijah-Baley]

No, this board takes 3.3v or 5v only.

I meant, maybe we can use a 9v PSU and use a regulator voltage, like a 7805 to get 5v and supply the amp circuit.
While we can supply the input buffer directly with the 9v getting more headroom and less distortion?

 

[KindCanuck]

I meant, maybe we can use a 9v PSU and use a regulator voltage, like a 7805 to get 5v and supply the amp circuit.
While we can supply the input buffer directly with the 9v getting more headroom and less distortion?

Oh of course, I didn’t even think of that. The volume pot is after the buffer, so it isn’t what is distorting, it’s the board itself. I did try it without the buffer and didn’t notice much volume loss, so maybe I can eliminate it… that would save space in my enclosure!