Tpa3118 power amp module with eqd tone job strip board as a pre amp

Locrian99

Well-known member
So this isn’t a pedal but it’s intended to go on a pedal board. Also interested in any tips or ideas anyone might have for this sort of thing.

It actually sounds really good and can get plenty loud to play with a drummer etc.

Little background as to what inspired me to do this.

I bought a ehx howitzers several months back to run into a 1x12 cab I have and to just have a little board with the amp right on it if I go to a friends etc. Then I ended up with a boss me-80 at my house and was playing around with it and really liked the headphone with the aux in as well (I realize common features on cheap practice amps). Well the boss me-80 while neat I feel I have a ton of pedals that does everything it does better. But I thought to myself can I get my howitzer to do this. So I looked at the 1wamp schematic over at electrosmash and a a few others to see how they do the aux in and set up a little box with to mix aux in into the signal. Then I made another little box to convert the speaker out to a headphone out using a trs jack and a couple resistors. Worked great but I found the extra boxes to be annoying. So the idea of trying this was born.

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This is one of those tpa3118 modules with a stripboard build of the tone job before it.
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It’s got an input, a power amp input (if you want to bypass the tone job), an aux in, speaker out and headphone out. I also added a master volume control that is right before the aux. both the power amp in and tonejob out meet here. It’s a voltage divider volume control. I realized a little late that my insulated jacks that I had to use for the outputs due to the bridged output of the 3118 needed more space so my jack layout is whacky.

I put this thing together to basically just try it out and see how it goes.

What I’ve learned. Power amp in is really unnecessary, I will remove that for sure. My pre amp pedals all seem to actually sound better going into the tone job rather than without. My laptop power supply I am using adds some noise that I’m not getting from my 12v 3.5 amp wall wart. And i am going to try some smaller resistors for the headphone out, i used 470 ohm and it cuts too much volume and also seems to me that it is cutting some highs. Everything else seems to be working great.

Here’s a gutshot of the disaster lol. 33B5549A-5235-49FF-9DAA-3AEACEF90585.jpeg

I picked up that enclosure off Amazon I think it was called like a 1590c it’s DEEP which was very useful.

My intention is to make another one of these now that I have an idea of what worked and what didn’t, and will do a little more experimenting with the headphone resistors. I will do a pcb build of the tone job for that and I think I may do a little perf or strip board up for my jack and star ground wiring, i literally forgot to ground a jack because the black wire just got lost in the mess. Wishing there was a full pcb layout to do this but I don’t think the power amp projects are coming anytime soon. Also the headphone and speaker outs will be moved to the side I think which will eliminate all stacked jacks and actually work better I think since this will be on the left edge of my board.

Any tips in things to add or make better are appreciated :)
 
Are you sure you TPA3118 is real? Can't tell from the pic in profile. Real ones look almost identical to the fakes. This is a fake one. Note that the chip only has 28 pins, not 32. And these HISSSSSSSSS.
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Also, use a power supply that does not have a ground pin on it's mains. You do need an earth ground, but must only have one from you pedal board to earth. If there is more than one earth ground, you will have a ground loop and that might be why you have noise from the 24V supply.
 
I posted the picture it was a board bought off Amazon. So I mean fake is possible. Most everything I had read said the fakes were 28 so I felt good about it.
Do you have a link to the seller on amazon? I'm trying to identify the real sellers and the fakers.
 
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