the (Ninja) Toaster

electric guitar amp

It looks like this

Pictures: new ones added .

What's Toastin' in 2007

First of all, the schematics are seriously out of date now! :-(

Although the design is unique, I realise now that the tone - well the main tone that I spent most time working on - really wasn't. I was inspired a lot by my impression of metal amps like the 5150 and Dual Rectifier. I tried to copy the hard, aggressive guitar sounds on my favourite Soundgarden and Metallica tracks. I was also building on the design of a previous hybrid amp I made with extremely high gain and graphic EQ. So it really ended up sounding and looking somewhat like a baby Dual Recto.

However, it has a basically flat frequency response, and several tone knobs that leave the voicing up to the user. It also has two alternative gain structures besides the metal one. So it ended up versatile enough that it could still be tweaked to sound good in genres other than metal. (mostly a case of not using the EQ to scoop out the midrange!) It makes a good bass amp too. The only thing really lacking is a presence boost, and there's nowhere to put one!

I went on to experiment with a modded Selmer Treble'n'Bass 50 S.V. (the ugly aluminium panel one!) to try and capture the sounds I couldn't get with the Toaster. I might write about this some other time.

The power transformer, output transformer, and some of the tubes came from a Sansui Q-55. This had a handsome blue and gold chassis (which I junked) that looked somewhat like a toaster. Hence, the name. I recently changed it to "Ninja Toaster" when I found out that Matamp make a Toaster amp, and I was (briefly) playing guitar in a band called Ninja Football. My Ninja Upgrade package ;-) changed the power tubes to 6550s (which just about allows driving 8 ohm speakers now) and added a Q control to the parametric mids, and a footswitchable gain boost using H11F1 optocouplers. Not to mention a laser-engraved plexi faceplate that lights up (see Pictures)

I've since found out that the Q-55 is used by some people as a hi-fi amp, and I'm sure they would be horrified at what I did to mine. However the chassis was totally the wrong shape and size to fit guitar amp controls, and since I didn't have a pair of the amps, there was no way I could use them for hi-fi. So too bad if you're a purist!

Finally, I was stoked to hear that Ray Ivers used my regulated power supply design in another project.

design philosophy

I started with the basic idea of being as different as possible to other designs. I checked out schematics of well-known amps on the Net and tried to avoid using any of that stuff. As work progressed some of my silly ideas got thrown out for more orthodox ones, because in A/B testing they were shown to sound worse. Coupling capacitors got smaller and the power amp got more negative feedback. Other ideas, like the dual parametric equaliser and regulated HT, stayed because I thought they were neat.

work in progress

These documents were prepared after the last major revision of the circuitry. It's sounding the way I want and there should hopefully be no more changes. (ed: I wrote that in 1999, since then, I have hacked it considerably. Visit the Toaster diary for details.)

build your own toaster

The Toaster is entirely my own design. I have decided to put it in the public domain so that anyone brave or foolish enough can make one. You might also want to incorporate some parts of it in another amp design.

Note: The schematics do not incorporate the very latest mods. I'll fix this whenever I have the spare time. (yeah right- that was 2 8 years ago)

Baxandall-type pre EQ

Overdrive stage

Dual parametric EQ

Power stage

Regulated HT supply

Auxiliary power supply

other schematics sites


Schematic Heaven

Ken Gilbert's stuff (OMG, he has a little Gilbert now)

if you wish to contact me, e-mail "steve at scopeboy dot com"
Home - Electronics