DIY low power guitar amp

[Domin]

I was thinking about it too, but it dont have oversrive or distortion channel, so i would need to use pedals for that and eq has some weird spots for guitar...but i was thinking about separating amp and speaker so i can connect something different to it https://blackstaramps.com/product/fly-103/ I try to make it firstly on breadboard and then ill see what i like the most
As a preamp i can use this too

[GibsonGM]

That looks pretty cool, but req's a lot of J201's, which are like silicon gold these days   For a little practice thing, I'd prefer to just cascade some Tillman-type gain stages....essentially, a distortion pedal with a hi cut or "SWTC" at the end of it, to feed what follows.   YMMV. 


The FLY103 certainly seems to be a powered ext. speaker, meaning it has an internal amp.  Since it's used with MP3 players, I can't see any reason a small FET preamp wouldn't work with it, tho the output levels are different  (there are topics here about that, about how to match the levels properly).   Of course, it will cost some money, where a real DIY thing would be CHEEEEP, ha ha.    The up-side is being able to use it fast, and pretty much guaranteed to have no/few problems.

[Domin]

I have bunch of 2N5457 so Im not worried about it I cant decide... Ill try to breadboard something and ill see. Or ill do separate preamp and poweramp thing

[GibsonGM]

That's what I'd do (and have done!) - the preamp and separate power amp...you could do a 'line out' from the preamp and use that with a DAW or what have you, too...

[mac]

I have a small amp on the breadboard right now.
It is a push pull BD139 & Bd140, both hfe 175, running at 9v.



R1 and R2 are 2k2 and I added two 2.2 ohm resistors between emitters. Output cap is 1000u into the HH 12" of my LC30.
Made a small heatsink for the BDs with zinc stainless sheet, but I guess only a screw, washer and nut can do the job at 9v.

Before the amp:
10k -- 100nf -- Big Muff input stage -- 10k -- 100nf -- a buffer which is wired to the diodes junction.
I set half Vcc by tweaking the buffer base voltage. The emitter resistor is 1k, and the base resistors are a 220k from B to Gnd, and a 250K-B pot from Vcc to B. It is near 100k or so.

Flat and clean even with HB.
But the fun starts when I put a Tube Screamer or Graphic Eq to drive it hard. 

As mentioned earlier, the push pull and the buffer alone gives versatility. One can build a lot of differents preamps to drive it.

I also ran it at 19v using a laptop PS. Just increased R1 and R2 to 4k7 and minor change to the biasing.
If you need more watts you can go higher voltage and/or increase the idle current. Maybe some Tip41/42.

mac

[Domin]

And if I dont want buffer before or is it needed?

[antonis]

And if I dont want buffer before or is it needed?

It depends on input signal source impedance..
(which impedance should be pre-amp stage output..)

[mac]

And if I dont want buffer before or is it needed?

It depends on input signal source impedance..
(which impedance should be pre-amp stage output..)

+1

I'll be posting it shortly.

mac