distortion project - G-Drive

[Branimir]

greets everyone!

well, finally my exams are coming to an end.. and after friday i'll have a month and a half time to work on my pedals and amps... hehe...

story goes like this...
two years ago my dad (electronic tehincian) got a bunch of used/unused electronic parts... resistors from 0 ohms to couple of Mohms... all sorted in boxes and stuff.. similiar thing with transistors and capacitors...
from an 70 year old electronic diy-er who apparently quit it's hobby due to poor eyesight and such....

and i remember i had a few boxes (matchbox boxes) of germanium transistors... i think AC 12x-something...

and couple of minutes of ago i got an idea...
why not try to make a Ge-project... 4 or more amp stages without diodes for clipping, just an idea to drive every of those transistors into distorted area... dunno how many stages since i have to check out how much hfe do those little critters have - and to compare with, for instance 2N5089...
to make a interesting, somewhat unique - distortion pedal that can deliever good rythm/crunch tones with a - what i like to call... a FAT lead tone... with lots of overtones, not too trebly but full a well rounded...
it's really abstract to define it how it sounds in my head  

anyway...
the trick is - i'll put probably somekinda of a dual pedal system - like you can have pedal set to a bit of crunch and stomp it to get a full drive (for those like me who don't like clean - really clean  :lol: ) .
simple tonestack - one pot system, dunno what type of filter yet (ideas very welcome!)

i would like to get somekind of fuzzface/mesaboogie type distortion wierd crossover...
to manage to get palm mute come out crunchy'metally' and when hit a power chord, it has that amp breaking kind of rumble in it...
anyway, somewhat out-of-control pedal with fat bottom...

heh...
ideas VERY VERY welcome...
i think i'll try with the AC128 transistors (i think i have those) a work later on the number of gain stages...

i would like to get some feedback from all of you since i never tried a - from the scratch project - and this one seems odd enough to try (there are distortion pedals made on the C4049!!! hehe)
is this thing possible as i think it is, or Ge's are unrealiable (mine are quite old!), i prefer not to use diodes for clipping, or at least not make a whole thing diode clipping device.

..
geez.
i'm spazing of now and dreaming... sorry!

greets from croatia!

[Peter Snowberg]

Greetings from Sausalito, California Branimir! (my apartment is in the middle of photo8.htm)

If you have not built any of the 4049UB based pedals, give them a try. They're a lot of fun.

It sounds like you have a sonic destination in mind and that may be hard to reach if your transistors don't have the magic hFE combination, but you'll probably end up in a place just as nice regardless of the selection of transistors.

I would start with a fuzzface and also build a Tone Bender Professional Mk II, and a simple single transistor booster. See what each sounds like in combinations with each one first, second, and third. That would give you everything from simple boost to a chain of stages that should totally wreck the signal.

You might want to try mixing Ge stages with 4049UB stages too . Hehehe.

Take care,
-Peter

[stm]

Here are my thoughts for your interesting project:

1) I second Peter's idea about the "building block" approach. It is easier and faster to go that way and try different combinations of distortion/gain blocks.

2) Also, building blocks for TONE controls can help. I came up with this idea (I'm sure I'm not the first, though) of having several tone controls in a protoboard and be able to use them when designing overdrive/fuzz effects.  Basic blocks would be like: BMP tone (with mid cut), RAT style tone (treble cutting), and perhaps a Fender and Marshall full tone stack.

3) In addition, I would make a test rig to verify the transistors. I would identify those with too muck leakage and discard them (or leave them for use as Ge diodes), and also would classify good transistors according to gain. Then when testing the circuit it would be easy to try-out different gain combinations.  I think GEOFEX had a suitable circuit for testing Ge trannies for leakage and gain.

4) Ge transistors have poor temperature behaviour. It is well known that fuzz faces change their sound with temperature. Once you have a good sounding circuit, you should see if it is possible to improve bias temperature dependence, like using universal polarization instead of a single resistor from Vcc to the base of the transistor, or by using other Vbe cancelling/compensating scheme.  I saw an article of a guy that made a self-biasing fuzz face!

5) Good luck!  


of making some building blocsk

[Branimir]

hey everyone!!!  

after a night sleep and after reading your posts i think i'll use a similiar approach to this build.

i doubt i'll be using a marshall/fender tonestack since i want this pedal to operate on it's own sound signature and putting an amp tone stack in it i think it would make too much of an impact of the sound. (i imagine putting all the way bass, 0 mids and all the way treble on marshall type tone stack BOTH on the pedal and the amp :shock: :shock:  - i would like to minimise that kind of effect of the Pedal's tone stack on the whole sound.

I'll attempt to reduce the certain harshness'es 'on the spot' instead of making them tweakable via pot or something.

anyway..
some thoughts that came across my mind...
let's say i'm to make a 6 stage distortion.
and to make all stages distort at a ... let's say at a lower amount..
and to make the whole distortion sound rise a bit and a bit through the every next amp.stage.
rather than making a 3 stages at full distort.

or make a 2 stages low distort and 3rd high and then next 2 again low and the last one higher...

anyway...
that's an idea..
now back to the schematic drawing and reading other similar projects for ideas, roll of caps and such..

transistors that i consider using are AC550.

cheers!