Jansen little brute mark 2

[Vinnie500]

Hello, I am looking for different ideas on a project I am working on. I am going to modify a practice amp into a bass pedal for a bass playing friend. There are a few reasons why... this particular amp has nostalgic value from his younger punk days, it is a good way for me to learn while mucking around with something reasonably complex but not that vaulable, and this particular bass player has a habit of wandering around the rehearsal space with boutiqe or vintage pedals bouncing along the floor while being dragged behind him. I figure the amp will be heavy enough to remind him of it's presence.

The three sounds he want's/uses in a pedal are; a very simple low pass filter, a distortion overdrive with dry blend or just not much loss of low end punch, and an over the top feedbackie gitchy noisy fuzz.

I have finished drawing up a schematic (due to the country being in lock down) and it has really hurt my brain. Hopefully the errors (which I am sure there are many) are obvious to spot and easy for me to solve. If not I will redraw it in Xcircuit to learn something else during this project.

Anyway thanks in advance for any thoughts or corrections people may have.

[Vinnie500]

I started tracing this to xcircuit so it was readable and thought I might just email Jansen (a New Zealand audio company) and ask if they kept their old schematics and turns out they do.

[iainpunk]

how about using the headphone out as the output of the pedal, going to a 3pdt switch to be mounted on the top of the amp.

in what extent were you planning to modify the actual circuit of the amp? just a bypass switch, or a full overhaul of the preamp?

[Vinnie500]

More of an overhaul. Like overdriving the second stage of that op amp or clipping diodes. Not sure yet I am hopefully going to get some time in the garage today. So I will try a few things and see.
I just thought more expericed people may be able to suggest some ideas, but I'm happy to experiment.

[PRR]

> a habit of wandering around the rehearsal space with boutiqe or vintage pedals bouncing along the floor while being dragged behind him. I figure the amp will be heavy enough to remind him of it's presence.

So what do you want? If you condense the Brute you get just another 1-chip 2-jack 3-knob floorbox which is easy to drag around. The stock Brute is heavy because it has a 10 Watt power amp and speaker; but you could as well nail a Hammond box to a concrete brick and get a drag-resisting pedal.

Wireless??

[Vinnie500]

I take your point. I guess what I'm saying is yes it will be just another three knob... but it will be in an akward and iinconvenient enclosure with a unnecessary 8" speaker. So I guess I just like the idea of it... others probably won't.
Anyway I will learn some stuff while doing the mods, already have, but anyway nevermind I'm sure I will work it out.

[PRR]

[Vinnie500]

Well while trying to add a clipping diode circuit I cooked the 556 transistor. On the way to working that out I replaced the opamp to a opa2312 and the bc550's to bc508's. And by happy accident now I have fuzz, so cool.
I do wonder about why I get fuzz now? is it the transistors or the opamp, or both? if anyone has time to give me a quick explantion that would be appreciated.
I will keep trying to figure it out myself in the mean time.

[Vinnie500]

I put clipping leds from pin 1 to ground and got the distortion I was after when playing through the mini brute power section. However when I plugged into to the preamp out as PRR described I get no distion from that output. Just thought  I would see if someone my be able to point out why, while I try to figure it out.