The next Big Muff question topic

[manson]

I recently got myself an old black russian big muff. Not the newest one, but more like a green army muff in a black case. I think I've read all big muff topics by now, but still have a few questions:

- How does the 2N5088 sound compared to the Smallbear 2N5133 transistor?
- I read that Q4 determines most of the gain. Will it be effective to swap trannies there and keep Q1-Q3 stock?
- What will a BC239 in Q4 do? Will it give the whole effect some less gain?
- Will a 0.0033uF in the tonestack give some more mids (compared to the standard 0.0039uF)?

Thanks, I hope you can answer these questions

[slacker]

The Q4 stage sets the amount of volume boost, it's there to make up for the volume lost by the tonestack. Changing the resistor values of that stage will probably alter the volume boost more than changing the transistor.
Most of the distortion/fuzz comes from the Q2 and Q3 stages.
I think using a 0.0033uF instead of a 0.0039uF slightly changes the mid scoop, you probably won't be able to hear any difference.
Have a look at the Ducan Tone stack calculator http://www.duncanamps.com/tsc/ that lets you play around with cap values and see the differences.

[manson]

Thanks slacker. So with the transistors it's really all or nothing for it to have some effect.

What about my first question I read the 2N5133 is the 'vintage' EHX transistor. Is it worth to put these in? How will it alter the way it sounds? Right now the standard trannies are still in there. I don't know which ones, cause they're unmarked. Except for a white and a green dot of paint.

[Unclerny]

Good luck with finding what went in the originals because I have a Triangle Muff and it doesn't sound anything like anything else I've ever heard called a Big Muff.  I can't find xter one for this thing and I can't speak for the 2n5133.  I guess you could install sockets so you can play with various xters and resister values.

Just bread board one, that's easier.

UE

[Meanderthal]

 The thing about the BMP is that changing the trannys makes much less difference that fiddling with the cap and resistor values. The 2n5133 makes a difference, but it's subtle. A little more grit, also described as a "less refined" sound. Slightly less sustain, a bit farther from the 'violin' sound EH likes to advertise. It does not change 'tone' at all, rather they tend to be a little lower gain than 5088. Change one cap, and you hear a bigger difference in tone.
That being said, I settled on 5133 for mine... but it's probably never going to be noticed by anyone but me. Mojo. You'll hear a bigger difference in their smaller parts count builds like a LPB or Axis/Foxey lady.

We can't tell you what you are going to like. Use sockets and compare different trannies. Some people don't like what the 5133 does!

[manson]

Thanks guys. Well I don't want it to be 'gritty'. I'm more looking for a somewhat smoother sound with just a little more mids. I'm thinking about changing all 0.1 caps and the 0.01 tone cap to metal film ones.

The tone stack in my particular BM is: 20K / 0.01uF bass, and 22K / 0.039uF treble. I already upped the 22K to 27K just to try.

[Mark Hammer]

The cult-like beliefs about transistors in the Big Muff really need to be shelved.  Indeed, when you sit back and consider just how many transistors can readily substitute for each other, how many can sub for the 5133 or 5088 and how many those two can sub for, AND how much variation there is in just those two transistor types, the odds of simply whipping the one out and installing the other in its place transforming any BMP from ho-hum to magic tone monster are pretty slim.  Especially when you consider the 5% tolerance of the emitter and collector resistors, variations in voltage drop of the 4 clipping diodes, etc. etc.

I'm not saying that NO productive improvements in subjective tone can be attained by subbing transistors.  Rather, I'm saying there will be a lot of hit and miss, and a lot of other things to play with in the formula.  As has already been noted, cap changes in the tone network can have a substantial impact. You will note that those caps themselves have an even wider tolerance than the resistors do, and that the region in the spectrum where the notch is generally created tends to be where the most noticeable frequencies are situated.  Consequently, simple unit-to-unit variation in tone-section caps can have an impact on output volume and voicing.

Certainly keep experimenting, and looking for the tone you like best.  The BMP is an extremely hospitable beast for experimentation.  Just don't expect the solution to be a simple straightforward replace-this-with-that one.

[manson]

Certainly keep experimenting, and looking for the tone you like best.  The BMP is an extremely hospitable beast for experimentation.  Just don't expect the solution to be a simple straightforward replace-this-with-that one.

Hmm that's both fun and a pity I'll try some things a keep you updated.

[manson]

Oh one more thing.. the 3 pots in my russian tank are of the most crappy kind I've ever seen. What values do I need to replace them with? Are they all 100K? And should they be audio or lin?

Thanks again!

[soggybag]

There are a lot of interesting BMP variations to build. The twentytwo sevenths is a BMP built around 4049 inverters and Jack Ormans FET  Muff, a BPM built with FET's.

[Yun]

Hey manson, just add a mids control, man.  look in my layouts gallery for my Super-Muff schematic. 

[petemoore]

  Anything HG/LN. Like 2n5088 or, MPSA 18's or...any darn HG Si with enough gain and noise characteristics you desire.
  Something like 2n3904...too low gain too high noise, not good candidate, will work but not the samem tried 'em because I didn't have better candidates available at the time.
  BC's just have a different tone to them, I forget the xxx numbers but they sounded interesting in it.
  I ended up back with HG transistors because they sounded good, and LN transistors because they're lower noise...2n5088 or whatever..