Hi all,
I'm making a guitar "pedal power amp" as a bit of an experiment after years of making Bluetooth speakers using the commonly available eBay class D boards.
For this project I'm looking at this XH-M542 board:
https://www.ebay.co.uk/itm/194520940446
I know it says 100w, and it likely isn't, but that doesn't matter. As long as I can get say 30w at least from a 24v/3a PSU, it'll be fine.
My first conundrum was adding a volume control. I can't remember which thread I read on here, but I arrived at a simple 10k log pot on the input. I think that was chosen as the input impedance of the amp is also 10k? I could be wrong.
My next hope is to be able to add a couple of extra switches to the pedal to give a couple more sound options.
I'm thinking a bass cut switch to roll off some low end and tighten up the sound a bit, and then a bright switch that allows some treble to pass the volume control when the volume is turned down. These are also called "treble bleed" circuits and are found on guitar volume controls a lot, as you may know.
So my question is what values will the components required need to be, and how they will be connected up in relation to the volume control.
Any help/suggestions will be most appreciated!
Jim
I'm making a guitar "pedal power amp" as a bit of an experiment after years of making Bluetooth speakers using the commonly available eBay class D boards.
For this project I'm looking at this XH-M542 board:
https://www.ebay.co.uk/itm/194520940446
I know it says 100w, and it likely isn't, but that doesn't matter. As long as I can get say 30w at least from a 24v/3a PSU, it'll be fine.
My first conundrum was adding a volume control. I can't remember which thread I read on here, but I arrived at a simple 10k log pot on the input. I think that was chosen as the input impedance of the amp is also 10k? I could be wrong.
My next hope is to be able to add a couple of extra switches to the pedal to give a couple more sound options.
I'm thinking a bass cut switch to roll off some low end and tighten up the sound a bit, and then a bright switch that allows some treble to pass the volume control when the volume is turned down. These are also called "treble bleed" circuits and are found on guitar volume controls a lot, as you may know.
So my question is what values will the components required need to be, and how they will be connected up in relation to the volume control.
Any help/suggestions will be most appreciated!
Jim
To clarify, I sort of know how these circuits would work in a guitar - I can get schematics for those online already. However, I am assuming that the values chosen will be specific to a circuit with a guitar pickup and the typical 250k or 500k pot. What I'm wanting to know are the values needed in a line level circuit that uses a 10k pot (if indeed that is the correct selection). 🙂
You will need a buffer amplifier with 500k input impedance.
The 24 V power supply must provide a current of 6a \ 4 ohm or 3a \ 8 ohm. But TPA3116 can also work from 12v with less power.
Im not going to be plugging the guitar straight into the power amp - there'll be a preamp pedal in between the guitar and the power amp - does that help?
For less power, you can use a PCB with 3110 or 3118 chips for $2.
You can use a 10k pot at the input of the power amp to turn down the volume. If the volume is not enough, pre-amplification is required. Only you can know about it.
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