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will this damage my pedal? question for pedal builders

BEMUSofNrthAmrca

Senior Member
Messages
448
I have a treble booster with a socket where the transistor is. I'm able to switch between germanium transistors, it came with an AC188, but I put a NKT275 in it.

I recently pulled 6 silicon BC239C transistors from a flatbed film editor amplifier and want to see what they sound like.

Is it safe to put a silicon transistor in a pedal designed for a germanium transistor?

I won't try it unless I know it's safe, I have no way to measure them, I'm hoping someone has some experience.

I'm dying to know whether I can use these silicon trannies to make a muff clone.

Thanks
 

analogmike

Platinum Supporting Member
Messages
6,988
The Problem is the germs are PNP and the silicons NPN so it won't work, without circuit mods, sorry!
 

BEMUSofNrthAmrca

Senior Member
Messages
448
Bummer.

I just read that BC239s were in some of the early Big Muff pedals. Is there anything I can measure or look for to determine if they will be suitable for the Muff circuit? They came out of an amplifier for a Steenbeck flatbed film editor from 1970s east Germany. I got a whole load of caps and resistors from it as well.

Can I get values from all these components with a multimeter?
 

BEMUSofNrthAmrca

Senior Member
Messages
448
Cool.

I want accumulate as many of the 46 components from recycled vintage parts or NOS parts from the 1970's.

I think I got a pretty good score with this Steenbeck audio amp.

I need a source for NOS sylicon diodes.
 

bt2513

Member
Messages
859
Bummer.

I just read that BC239s were in some of the early Big Muff pedals. Is there anything I can measure or look for to determine if they will be suitable for the Muff circuit? They came out of an amplifier for a Steenbeck flatbed film editor from 1970s east Germany. I got a whole load of caps and resistors from it as well.

Can I get values from all these components with a multimeter?
Getting exact specs on the transistors will require some additional work to determine gain and leakage (if any). Check out geofex or do a search on germanium transistor values for fuzz faces. Should pull up the relevant article. You'll need to solder up a switch in conjunction with some resistors to get started. There's some math involved as well. Just to be clear, the process is rudimentary at best and subject to many things outside your control.

Edit: I should also add that most builders use dedicated equipment built for this specific type of work to determine if vintage parts are even operable much less within a relatively tight range of usefulness to the BM or FF circuit. The BM may be more forgiving -- I'm not familiar with the specifics of it.
 

BEMUSofNrthAmrca

Senior Member
Messages
448
I confident that they are operable.

With my limited knowledge of components, building the circuit is more than likely the only way I'll be able to tell if they are good enough for a Muff pedal.

I've been looking for a project and this could be a good one. I'm thinking going so far as to make an enclosure out of sheet aluminum to mimic the old Muff ones.

I'm selling my delay pedal, so maybe I'll give the project a decent budget.
 

jdel77

Member
Messages
9,997
Testing transistors as recommended in post #4 won't give you jack squat. That's for testing resistors. You have TRANsistors.
Get a multimeter, and in one of the corners of the face of the meter should be 3, 4 or 5 tiny holes in a line or in a circle. They are for testing hFE, or gain of a transistor.
You need to look up a data sheet on Google for your specific transistor.
Then you need to work out which is your base, collector and emitter. Which of the 3 leads is B, C or E.
Then you need to insert the transistor into the correct orientation of those holes to give you a figure on the multimeter.
Muffs like transistors with high gain. On average, a current production 2N5088 will give you around 500 - 800 hFE. Some silicon BC107's and 108's read much lower in the early 100's or 150.

So test them out to see if they fall into the correct gain range. If not, your muff will sound very low gain and muffled. Like a muff with the gain turned right down.

And to expand on Analogmike's point, not all Germaniums are automatically PNP, or positive ground. There are some Ge transistors that are NPN, or negative ground. For example, the tranny's used in the BYOC Fuzzface are awesome, I grabbed a few and have 2 in my BYOC modded Fuzzface. If you can find the AC127's, get them, but ONLY if they have been verified as being in the correct gain range.

If you need further info, head on over to the BYOC forum, or one of the DIY pedal forums.

Also, the Culturejam/Madbean Gruntbox is the KING of all DIY Big Muff platforms. You can build the pcb up to any of the 4 main Muff iterations, socket the transistor spots and go nuts testing out transistors.
 

BEMUSofNrthAmrca

Senior Member
Messages
448
Testing transistors as recommended in post #4 won't give you jack squat. That's for testing resistors. You have TRANsistors.
Get a multimeter, and in one of the corners of the face of the meter should be 3, 4 or 5 tiny holes in a line or in a circle. They are for testing hFE, or gain of a transistor.
You need to look up a data sheet on Google for your specific transistor.
Then you need to work out which is your base, collector and emitter. Which of the 3 leads is B, C or E.
Then you need to insert the transistor into the correct orientation of those holes to give you a figure on the multimeter.
Muffs like transistors with high gain. On average, a current production 2N5088 will give you around 500 - 800 hFE. Some silicon BC107's and 108's read much lower in the early 100's or 150.

So test them out to see if they fall into the correct gain range. If not, your muff will sound very low gain and muffled. Like a muff with the gain turned right down.

And to expand on Analogmike's point, not all Germaniums are automatically PNP, or positive ground. There are some Ge transistors that are NPN, or negative ground. For example, the tranny's used in the BYOC Fuzzface are awesome, I grabbed a few and have 2 in my BYOC modded Fuzzface. If you can find the AC127's, get them, but ONLY if they have been verified as being in the correct gain range.

If you need further info, head on over to the BYOC forum, or one of the DIY pedal forums.

Also, the Culturejam/Madbean Gruntbox is the KING of all DIY Big Muff platforms. You can build the pcb up to any of the 4 main Muff iterations, socket the transistor spots and go nuts testing out transistors.
Thanks for the reply.

You actually helped me out regarding my BC239Cs. If I can make sure the gain is somewhere above 500 Hfe I will go ahead with my build. I've read that BC239s are generally found in the more aggressive sounding Big Muffs. I understand the Resistors and Capacitors have just as much to do with the sound of a Muff as the transistors. Won't most BC239 transistors be fairly consistent? I've read that silicon trannies aren't as inconsistent as Ge ones.

Since I posted this thread, I've gotten my hands on an old GE-1 germanium PNP tranny. I figured what the hey, so I put it into my Treble Booster. Hot damn, if it doesn't sound a bit louder! I'm kind of liking the sound of the GE-1. I've now got the AC188, NKT275 and the GE-1 to play with.

I'm going to head on over to those pedal building forums you recommended, but I have one more question I'd like to ask. I've got a large supply of 60s carbon composite Resistors that I've recycled from various radio and audio circuits. If I measure these with a multimeter and find healthy ones with values fit in the Big Muff circuit, am I okay to use them? Could I benefit from using old parts vs. new ones? Can I get some of that old electronics mojo into the pedal by using recycled and NOS parts?
 

jdel77

Member
Messages
9,997
As for consistency, you can't assume anything :). You pretty much have to hear them or test them first to find out, some could have gains all over the shop, and could change the sound of the circuit. This is why Muffs are so hit and miss, they just grabbed whatever was on the shelf and out it went in the box. But usually, yes, Si transistors are more consistent and stable.

Yep, playing with transistors will yield different results. Socketing them is a must, unless they are matched and measured for gain and leakage.

Regarding the Carbon Comp resistors, measure them with a multimeter first. Values can drift over time, so a 47k resistor could be slightly more or less. Put enough old resistors or caps in a circuit with them all drifting around off mark and the pedal could sound very ordinary. If the component measures up, sure go for it. There are new Carbon comp resistors being made, Allen Bradley do them.

Vintage Muffs used ceramic caps for most of the caps. Guys who are just vintage nuts like Marc Alfs from Skreddy use ceramic capacitors in their muff clones. I;ve built clones with ceramics and regular poly caps, and I will say that I hear a grindy almost grainy midrange in there with the ceramic caps. The Muff tone control by nature really cuts mids out of the circuit, so that extra mids presence is sometimes welcome. Run that through a midrangey amp like a Marshall or a Vox, and Muffs just deliver live.
 

BEMUSofNrthAmrca

Senior Member
Messages
448
As for consistency, you can't assume anything :). You pretty much have to hear them or test them first to find out, some could have gains all over the shop, and could change the sound of the circuit. This is why Muffs are so hit and miss, they just grabbed whatever was on the shelf and out it went in the box. But usually, yes, Si transistors are more consistent and stable.

Yep, playing with transistors will yield different results. Socketing them is a must, unless they are matched and measured for gain and leakage.

Regarding the Carbon Comp resistors, measure them with a multimeter first. Values can drift over time, so a 47k resistor could be slightly more or less. Put enough old resistors or caps in a circuit with them all drifting around off mark and the pedal could sound very ordinary. If the component measures up, sure go for it. There are new Carbon comp resistors being made, Allen Bradley do them.

Vintage Muffs used ceramic caps for most of the caps. Guys who are just vintage nuts like Marc Alfs from Skreddy use ceramic capacitors in their muff clones. I;ve built clones with ceramics and regular poly caps, and I will say that I hear a grindy almost grainy midrange in there with the ceramic caps. The Muff tone control by nature really cuts mids out of the circuit, so that extra mids presence is sometimes welcome. Run that through a midrangey amp like a Marshall or a Vox, and Muffs just deliver live.
Sounds good. Thanks for all the info man. I appreciate it.
 




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