Are there any low-power class D amplifiers that are not crap for guitar amplification

[indoubt]

When ordering on Ebay patience is a virtue

I think that for this application the TPA3116 PBTL is advantageous as it is a mono board. If you take a 4 ohm speaker it can deliver quite a lot of power for such a little amp.

Note that if you want to use 24 volts supply you might be very close to the edge as most capacitors are only rated for 25 Volt. A little lower voltage might be advantageous for that reason.

In the guitar cabinet I have an 8 ohm speaker so it is limited to 18-20 watts of power on the 15Volt computer power brick and slightly more on the Battery (which is about 16,8V when completely full). This is more then enough as the speaker is only rated for 15 watts. Nevertheless it goes very loud bevause of the high sensitivity. Not for large venues of course but for cafe sessions it is more than enough.

Bottom end is acceptable too but not as good as a full sized 12" speaker cabinet or a good 10" of course

Note that most of the TPA3118 PBTL boards have high gain. That is not bad but requires extra care of the cabling. Signal wires should be shielded or twisted.

Electric guitars like amplifiers with high input impedance. I do not know what the input impedance of this board is so that is why I took the precaution of the distortion pedal/line driver. If I would have to do it again I would probably look for a low gain with high input impedance pre-amp circuit.

My brother liked the idea and is now building (with my help) something similar but for accordeon/microphone. In that situation we have the problem that the preeamp is driving the TPA3118 board into oscillation so not all pre-amplifiers are suitable.

I also made a design for a 10" speaker 60-70 watts cabinet but have no use for it currently

 

[mnesarco]

TPA3118 PBTL board has just arrived. It works out of the box with the same preamp. No oscillation, not motor boating. It just sounds great. I will try it with different speakers just to experiment.

Thanks for the suggestion guys.

 

[indoubt]

Great!, happy building!

What pre-amp do you use?

 

[mnesarco]

Great!, happy building!

What pre-amp do you use?

Nothing special, just two channels (Clean, Dist) basic Op amp Stages.

 

[Gnobuddy]

TPA3118 PBTL...works out of the box...sounds great.

Congratulations! Glad to hear that we were on the right track, and the problems you were experiencing are gone.

I assume you're running the TPA 3118 direct from the 19.5 volt laptop brick (no DC-DC converter to drop it to 12 volts)?

-Gnobuddy

 

[mnesarco]

Congratulations! Glad to hear that we were on the right track, and the problems you were experiencing are gone.

I assume you're running the TPA 3118 direct from the 19.5 volt laptop brick (no DC-DC converter to drop it to 12 volts)?

-Gnobuddy

It works with 19V Laptop brick very nice (direct). But I have tested it with a 12V PSU and it works too, very clean sound.

 

[dotneck335]

Milkman Amplifiers use an IcePower Class-D power section in their Half and Half designs and many rave about the great sound they achieve.

 

[AquaTarkus]

I would strongly recommend using a valve!/tube preamp to give some had jazzy warmth to your amp's superclean sound. Doesn't need to run at super-high village either.

I also strongly reccomendg using guiyar speakers both for their warmth and high efficiency / sesitibity, typical in the e tag geez of 96-1000 dB!/ watt @ 1 metre . Look around for suitable speakers and prices made by Celestipne, Eminence or Warehouse Guitar Speakers. I'm thinking that Eminience's Swamp Thang is probably close to the sound you want.

Sent from my phone with Tapatalk. Please excuse any typpos.

 

[mnesarco]

Milkman Amplifiers use an IcePower Class-D power section in their Half and Half designs and many rave about the great sound they achieve.

Wow, those IcePower modules are impressive. But too big for this use case. I am building a small portable Amp. The TPA3118 PBTL board Fits just enough. But I will consider IcePower Modules for my next project

Thanks!

 

[john65b]

I had a blown Crate Powerblock that previous owner really buggered up trying to fix...I pulled the circuit boards and just dropped an ICEpower 200ASC into it - and works even better than the original. I used the +/- 12vdc on Icepower module to power the Crate Powerblock Preamp section and worked a treat. I use my homebuilt tubeamp exclusively, so this sits unused...I just posted it on swap meet if anyone was interested...

 

[Blue777]

I know this thread is a few years old but I am making a guitar amp with the 3116 class D chip. I hooked up a guitar straight into the board and powered it with a 12v hard drive transformer. It of course was not a good sound. Brittle and thin. I presume I need a pre amp and probably with tone and volume controls but i don't know what kinds of specs to look for that would work with my amplifier board. And I was curious if anyone thinks I need more than 12volts for the power for that amp board? My speaker is 4 ohm by the way.

 

[Printer2]

So you went straight from the guitar into the board? What speaker and guitar are you using? What kind of music do you want to play?

 

[leadbelly]

Link for board information?

 

[rongon]

The input impedance on my TDA3116 based amp is 10k ohms. That's way too heavy a load for a guitar pickup. If you went straight in from the electric guitar to the TDA3116 amp, then I think that's why it sounds wheezy and thin.

Yes, I'd use a preamp in front of it, with tone controls. You won't need very much gain, because the typical TDA3116 amp board comes configured for something like 26dB gain (that's 20X gain). Maybe a single 12AX7 and a Fender-style tone stack would do it? Make the first 12AX7 the input tube, using a 1M ohm grid leak resistor and a 10k grid stopper. Then comes the tone control stack, and then the second 12AX7 could be a cathode follower. Or even a 12AT7 might work well for guitar (more harmonic distortion than a 12AX7, a bit less gain).

I'd also put a low pass filter in there somewhere, since electric guitar has zero frequencies above about 5kHz (and that's stretching it).
--

 

[jjasniew]

Do you use effects pedals? As was said the input of that 3116 is too low for a direct connection to guitar, but if you put your pedal-board in front of it, the output of any one of those should drive it better.

By pedal board I mean perhaps a graphic EQ pedal, a compressor pedal, a Wah pedal, a distortion pedal, a phasor / reverb / echo multi-effect pedal - all mounted on a board at your feet (with its own power supply). Plug your guitar into that chain, then your 10K input class D amp.

 

[Blue777]

Reply to All above and below:

I WILL TRY to efficiently address all questions and clarify for All of you:

1- This will be all solid state. 2- Super small to fit in backpack. 3-See photos for lots of questions answered. 4- I play weird rock & roll but positive in nature. 5- No tube pre amps needed. Looking for correct solid state version with 3 tone knobs and volume and headphone jack. 6- Speaker is 4 ohm rated at 40 watts (I presume up to 80 watts rms) 86 Db. Seems good and I don't mind a bit of distortion. 7- EQ pedal/pre amp OUT is 1K ohm. 8- Guitar is shown but I use many. 9- Having a hard time finding schematic for amp board but i know it's a 3116 and photo attached has all the info I have. --- GENERAL INFO: This is a super small travel rig that will get MIC'd into a PA to get the warmth and lows that aren't right out of the speaker (works great like this for me and has a compression i like). This amp will act as my monitor but also feed into a PA system via microphone. I wanted the 100 watt board to have this thing be loud enough on live stage for my monitor but mic'd too for house sound. --- (MUSIC DEFINED: Mature but a bit strange and intellectually stimulating and even some spiritual insight. But also with roots rock & roll. Think if Morphine met Tom Waits in a circus tent for a strip show and invited Leonard Cohen to riff then the stripper comes out and puts clothes ON and then Neil Young comes in to remind all that ROCK & ROLL WILL NEVER DIE, with good heart and GROOVE!)

 

[PRR]

A 4-inch speaker with no box/baffle WILL be wheezy and thin.

Even my $9.95 KENT has a "box". (cardboard)

 

[Blue777]

Yes, I understand sir, but I test first without a box. Box comes when i know the elements i must mount. UPDATE: I realized yesterday that the main problem was with the first guitar i used (borrowed). Now it works fine but I would love to have some help with grounding issues. In photo attached you will see I have grounded the power wire with the ground of the guitar plug. It sounds perfect. Zero hum. But when i unplug the guitar input (with or without pre amp EQ) there is noise, not just hum, pretty bad noise. So, is there a rule of thumb on how to ground everything appropriately? Attachment:

 

[Printer2]

All guitar amps use a switched input jack. When there is nothing plugged in the switch shorts out the signal lead to ground. When we ask what kind of music you want to play (my fault not specific) we really mean what range of sound you want out of the guitar. The graphic EQ shows that you like the mid scoop of some guitar amps but that make be also due to no cabinet around the speaker.

Speaking of, is this your intended speaker? Do you play with a band as it may not cut it at those levels. Also you are not getting 100W on a 12V supply.

Speaker is 4 ohm rated at 40 watts (I presume up to 80 watts rms) 86 dB

The speaker is not a guitar speaker I take it. Depending on your volume it may not take the power it is rated for. You will not be getting 100W, 50W will require a 24V supply that is regulated as this is the maximum the chip takes. Get a 19-21V laptop power supply.

Basically find yourself a distortion pedal you like the sound with the type of guitar you intend to use and see if you can find the schematic for it.

 

[Blue777]

PRINTER 2: "Also you are not getting 100W on a 12V supply."- I understand. Thanks.


I think it not efficient to reply to your other points but I hear you and am paying attention.


I THINK what i need is a rule of thumb or exacting comments for GROUNDING APPROPRIATELY the board and all else and FINDING SPECS FOR THE LOUDEST 4 INCH SPEAKERS i can find. The amp says it goes down to 2 ohm.