Build Your Own Clone Message Board

Okay, one for the BYOC old timers. I've got one of the old OC44-based Rangemaster kits, wired like so for negative ground:



I've added a 6-way input cap selector and I'm planning to add 1M resistors to ground at the imput and output to eliminate the loud BANG that I get turning it on! My question is this. If I want to add a power diode like an 1N4002 to protect against reverse polarity (like the one on the Ultimate Fuzz), where would I put it?

Hi Palladin

You had the good grace to answer my post so hopefully this'll help!

Check out the link below on Fuzz Central. It gives the schematic for a NPN Rangemaster with the diode in parallel with the power supply.
Fuzzcentral

Is this diode really essential? I was on building the Rangemaster myself but was going to leave this mod out.

Here's a Rangemaster PCB from GGG that I put together for a guy I know. I used two 2.2M pulldown resistors that can be removed if not needed. I've heard some folks say that they hear an increase in overall brightness of the sound when pulldowns are used. I've never needed them myself since I don't have any popping issues. One thing you might want to consider adding is the Ge diode across the emitter and base of the GE tranny. This provides thermal stability for the tranny so that heat won't have an adverse affect on the sound. Something Ge devices are known for. I've also socketed the input cap so you can either use a rotary switch to dial in more or less lows or to directly insert a value not used in the rotary switch.



This is the rotary switch used to change input caps. The values I chose to go with are .002uf, .003uf, .005uf (stock Rangemaster value), .01uf and .022uf

_________________
"It’s your soldering."

Thanks for that! Unfortunately mine is PNP wired negative so I'm still a bit confused because it's sort of a mix between the two. What I really need to know is what direction the diode needs to face to ground, and where in the circuit to stick the other end.

It's definately not an essential mod, mine has been running for years without it and most clones don't seem to have it but my understanding is that it would be better to have it than not so I thought I'd stick it in while I had the box open.

Stephen - Nice work, I hadn't considered putting a diode there. Does it affect the sound? Can you use it on similar Ge devices (fuzzes) without messing things up?

I think a little extra brightness in a treble boost won't be a bad thing, so I'll use the pulldowns. The pop really is quite bad in my unit so I'll accept it as a tradeoff.

My input cap values are, rolling back: 0.0047 (stock), 0.0068, 0.01, 0.022, 0.033 and 0.047 (full range). I think it gives a nice spread. I didn't go for anything smaller than stock because I found the stock value too piercing to use with my tele and the original idea was to have more lows to even things out a bit when changing guitars.

The added diode makes no audible difference that I can hear. As for using it with other Ge devices I don't see any reason why it wouldn't.

I went with the lower cap values strictly for use with humbuckers. These values thin out the sound giving humbuckers a quasi single coil kind of sound. Sort of the way the higher values fatten up single coils to an almost humbucker kind of sound.

_________________
"It’s your soldering."

Right, according to that fuzzcentral article the power diode should be parallel to the power supply. In the diagram in my post above, it looks like it should go from ground, point towards the circuit and go in at the bottom left of the board (POS).

Does that sound right?

Okie-dokie, I've made my mods. Replaced all resistors with metal film, added input/output pulldowns, a power diode, and at Stephen's suggestion a germanium thermal stabiliser diode. Here's the pic:



Yes, yes, I know it looks like electronic butchery but this was my very first pedal and it went through a bunch of mods before I discovered solder braid. The Ge diode looks like it's crossing the emitter and collector, but that's a trick of the camera - it really goes between emitter and base. The power diode is under the board, parallel to the lower cap and pointing right -> left; there was no room to top-mount it on the board.

Results: Excellent! That little OC44 has never sounded sweeter. The metal films have greatly reduced the noise level, and the pulldowns have totally eliminated what used to be the loudest pop on my pedalboard. Obviously I can't see the electronic effect of the diodes, but they don't seem to have had any adverse effect on the tone so I guess they're working properly.

Very happy with how this turned out!

It's right at the top of the thread in the first post.

If you're looking for the unpopulated PCB, you can still use the one above. This kit was originally intended for use with positive ground, it's just been wired up differently.