While starting some Cherry Bomb not-quite-a-repair NPNs, I got to thinking…

[jessenator]

There are a few projects I'm thinking about (much later) and a Cherry Bomb a friend lent me to take a look at, so thought I'd ask. I've seen the recommendations in the Cherry Bomb build doc, as well as the meatqlaw, include a number of alternatives and hints at favorites.

The current one has two BC109s in Q1-Q2, and a 2n2222 can at Q3.

In the realm of silicon fuzzes, overdrives, etc. where does BC reign end and 2N/PN dominion begin? I suppose the easy answer is "whatever the original / new build doc prescribes"

[greysun]

I built 2 of these and use them sporadically, but always wish the distortion wasn't so... bit-crusher-y? lol. The EQ is actually really great and the pedal adds really nice color when used with other pedals (especially muffs and rats), but on its own the distortion is a tougher sell...

I used a mix (as the 2015 doc said) of BC108 in Q1 and Q2 and BC109 in Q3. I've been meaning to swap them out with others to see what happens (thank GOD for sockets, right?), but with a couple green beans and eggheads (and soon, husky boys), I've always had backups of other overdrives. The Greenbean sounds great with some guitars, not so much with others, and the egghead works great with an amp that has a lot of treble (I have an Allen Accomplice) but not with a lot of bass (I also have a JTM45). obviously everyone's mileage will vary depending on their settings, tubes, other pedals, etc., but that's been my experience.

If I could tame the distortion, the cherrybomb might be my go-to pedal because the treble/bass controls for whatever reason work better than any other pedal in my chain. If I could go back, I'd just buy a bunch of the transistors and test them all... maybe this summer.

[greysun]

... And now I'm down the rabbit hole hehe...

From what I'm reading, anything that contains a 300-400 hfe range will work, but some might require new resistors (?) for biasing.

I guess my question would be what happens if you don't change the resistors, but find transistors that sound good to your ears? Are there long-term consequences for the transistors, or is it just how the sound is generally affected? Or would the transistors just not work at all?

[jimilee]

The resistors are for biasing, so it wouldn't make any long term issues. I'd drop a trimmer in there and experiment.


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[jessenator]

Nice that we have all of these fun toys to help these days. 


Shouldn't be hard to match the working ones. I measured the two working BC109s with an hFE of 270/271; the reason I replaced the 2n2222 can with a TO-92 one I had on hand is it was registering as a thyristor on the TC7—had a few do that, with only about 5% from the lots I've purchased failing in that way. Sometimes I can test it in rapid succession and I'll finally get it showing up as an NPN, but that 5% are complete fails.

That said, it's got to be more than just its current gain that makes a transistor do what it do. I mean, yeah, germs have their own eccentricities, what makes us claw for the silicon R@RE? I suppose it's how it's being used in a circuit?

Not having EE training, where is it most critical? Descriptions and build docs for things like a Horde Howler (TS/SD) indicate that its NPNs are buffers and don't significantly color the tone. Tangentially/analogously, you have circuits that depend on an op-amp for its tone (Rat), while others it does bugger all (TS/SD).