Building Class-D 50-100W guitar power amp as a beginner

[newprint]

Hello ! I have to premise this message by saying that I'm a beginner DYI electronic hobbyist with a software engineering background.

I want to build a portable, 50-100 Watt class-D amplifier (i.e. amp head) for playing jazz guitar, on top of that I also intend to build a cabinet with EVM12L or a similar speaker for a clean sound. Some of you could say this is terrible idea, since class D guitar amps and amplifiers are cheap & readability available. Fender Rumble 40, class -D, has a very clean jazz sound for a bass amp, on the secondary market goes for about $150 used/ $200 new. Also, I already have guitar combo specifically designed for jazz : Ibanez Wholetone WT80, Class-D, 15" speaker, but I want something different.
Here are my parameters:
- A simple board that I can wire-up and put in the simple metal case. Doing some online research, Icepower & Texas Instrument boards are are popular choices. But I have no idea what boards will fit my needs. There are number detailed DYI projects on YouTube for home audio (not guitars) using Icepower boards, but those projects used boards that handle 1000W+, which is an overkill for what I need.
- I have no issues if boards is for PA or HiFi as long as it gives me clean signal to drive the EVM12L.
- Pref. build in power supply.
- Pref. no preamp or eq on board. Just a volume knob, line level input (external pream & eq will be used) and a speaker output.

Any suggestion or critique are welcomed.
Thank you !

 

[Matador]

Why class D? You can get that wattage pretty easily through a class AB MOSFET power amp.

 

[abbey road d enfer]

Any suggestion or critique are welcomed.

There are many boards using TPA3116D2, capable of 2x50W into 4 ohms.

 

[rogs]

I'm with Matador on this one..... building a class D amplifier as a 'one off' hobby project is going to be a challenging task.
It is possible to build a class D amp using discrete 'thru hole' components - I've actually done it - but it's not something I'd ever do again !

There are lots of modules available as building blocks - like the one Abbey has linked to in post #3 - but creating a decent SMD layout for a complete one off project is not for the faint hearted. Getting noise down to acceptably low levels - and making a reliable amplifier - will likely involve several prototypes.

For a 50 - 100 watt 'clean' guitar amp, a class A/B Mosfet amp... using lateral mosfets... has got to be a simpler solution as a 'one off' hobby amp build.
Take a look at Rod Elliot's page here: https://sound-au.com/project101.htm as an example.
There are fewer lateral mosfet choices these days - I don't think there are any T03 lateral mosfets still in production? - but Exicon still make T0247 style devices..

If you do want to go Class D, then I think buying a complete amp module and simply adding power supplies, enclosures and connectors will likely produce a better result, as a one off hobby project...
I've used Hypex amp modules before, and found them excellent, but they're not cheap.
I'm sure others will advise on different types of class D module they've used, and can recommend?...

....Just my 2 cents

 

[daschnoz]

50-100W --- Do you have any idea how loud 30W can be? Don't let the marketing fool you. Unless your amp is your only amplification and you need to fill the arena with no help from the house system, you can get by with much less power. I played gigs for years with a 30W head that I built (2-channel, single ended class A with parallel 6L6 power tubes). I was often told to turn down (volume knob was at ~6, full stack with Weber Signature 12 speakers). The other guitarist in the band had a 100W Marshall head. He was always too loud, even with the volume at barely 1, and his tone sucked.

There are many boards using TPA3116D2, capable of 2x50W into 4 ohms.

If you are planning to go in this direction...
Instrument watts and program watts are 2 very different things. Try pushing 100W of a single instrument through that 100W rated living room speaker cabinet and it won't last long before the voice coil is toast.

In another small amp build that I built, I used a 30W class D board from Amazon. I was sure to design the pre-amp such that I was not overloading the input or clipping the power amp. Pushing a heavy distortion guitar through it, the amp pushed about 20W into 4 ohms for about 5 minutes, then it made some weird noises and died. I ended up replacing that board with a 100W board and it is still running fine, pushing about 35 watts max. So if you do go this route, make sure to oversize the class D board.
100W board - https://www.amazon.com/gp/product/B082F7P184/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

For these boards, you will need a +24V power supply (another $15-20 board from Amazon).
Power supply board - https://www.amazon.com/gp/product/B07PS9M4DJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Most of these power amp boards don't have enough gain for an instrument level signal to reach full power output, but if you oversize the power amp board, there may be enough gain for what you need. Some of the reviews on these that I have read note that a pedal with some gain is usually sufficient to get full power out of them.

You will lose the class A/AB power amp "mojo", but if all you're looking for is something to drive current through the speaker, there's nothing wrong with class D. It's just a different way of getting the job done. Keep in mind, all of your tone will come from the preamp, so that part of the signal chain will carry more weight. Unless you're in a studio using a high $$ gear, it's likely that you'll never hear the difference, especially if you're in a crowded space with background noise.

 

[DFischer]

I've "built" several amplifiers with IcePower boards and I can recommend them. I'm currently using a 50ASX2BTL for my main bass amp at 170W. I've also used a 125ASX2 in BTL mode for 500W. I can tell you that the extra wattage is completely unnecessary for my needs. The 170W is plenty clean for most bass applications. I'm also currently boxing up a 100AS2 as a stereo power amp for a pair of Auratones I recently built. One advantage of the AS2 is that you don't need to provide input buffers. There are already balanced input buffers on-board. However the design manual for the ASX series has a schematic with the recommended buffers that is pretty easy to build. A small perfboard will hold the buffer opamps and a voltage regulator for the buffers.

From what I can tell, the AS series is much more straight-forward to drop in a box and wire up to switches and connectors. However, I haven't actually done mine yet. For your application, the 100AS1 might be right. It's 100W at 4ohms in mono, with onboard power supply and input buffers.