Big Muff not Fuzzy enough

[bdevlin]

Just finished a Big Muff PI from the GGG layout.  I used half 5088's and half 5089's. 

In comparison the some of the sound samples I have heard on line and the EH Lil' Big Muff demo on Comcast, mine seems to be lacking a bit in the Fuzz character.  All of those quirky little artifacts that you'd expect to hear from picking noise and two note bends is not there. 

Any suggestions?  As I write this I am wondering if a compressor in front of it might get me what I want.

[petemoore]

  I always test the voltages for bias...BMP should be able to get pretty fuzzy..
  So if it's actually working right and you want more...
As I write this I am wondering if a compressor in front of it might get me what I want.
  ...try an OS or Ross Comp...or booster of some type...that should 'hyper' it.
  Back in the 70's...Bill had the BMP, the LPB [and some other Leetle EH box with a phono jack sticking out of it]...Very Fuzzy through Fender Quad..Youch !!

[Mark Hammer]

I've made  3 of them. Same schem, same trannies (5088), same everything.  And they all sound different.  One adds a bit of grind but nothing that would earn it the label of more than an overdrive.  One sounds like you'd expect.  And the other is insane as if you've stuck 2 boosters ahead of it.

It happens.  Just too many things in there with 5% (and greater) tolerances.

[oldrocker]

You could try the Yun mods for the Creamy Dreamer.  This mod is pretty much just removing the emitter resistors with jumpers on the first three trannies.  My Big Muff wasn't at unity and was quite lame before I tried Yuns' mods.  I also removed some caps [470p or 500p] that went across the diodes but I'm no sure that was required because I read that some disagreed with that.  But my Big Muff now has a huge sound.  Fuzzy overdrive is very pronounced but I don't know how it compares to stock or other BM pedals.  But hey it's an easy tweek.

[bdevlin]

It happens.  Just too many things in there with 5% (and greater) tolerances.

That just makes all too much sense and speaks volumes for the benefits of breadboarding which I don't have the patience for.  I think I will first try a booster or compressor in front of it, then I might socket the bias resistors and the diodes and experiment. 

[petemoore]

  I like the pre-boost technique on a switch on pretty much anything that sounds good that way, because I use it.
  ...And...because I opted for 'em early...it's an easy way to get a pre-settable amount of boost on a switch.
  Another non-followed option would be to alter the internal gain structure via SPST, SPDT, DPDT, or 3PDT switching, say from about what you have there, to Yun specs or what.
  What being the operative word for my opting for the extra gain stage w/volume control and often a voicing cap/mod.

[Rick Hardslab]

If you socketed your transistors, try using four 2n5088s.  To my ears they seem to have a bit more dynamic range than the 89s.  Some more 'artifacts' might get through if the signal isn't so gargantuan all the time. 

[bdevlin]

Switching out the transistors did not do too much.  I think I have 5088' in there now.  One thing that I did do that seemed to get me closer was change out the Sustain pot.  The one I had on there measured at only 84k Ohms.  I went and slapped in a 500k.  Does the extra 400k do anything?  I can't answer why it might but it seemed to help.

[brett]

Hi
Yun also suggests adding extra diodes so that there are 3 antiparallel instead of 2.  That could also be achieved by converting to 1 LED.

A large source of difference in BMPs will be the base current and input impedance of each section.  This will vary with transistor hFE and a few other things.  It can be controlled by changing those 100 ohm resistors.  Yun replaces then with trimmers, but I'd be tempted to simply replace them with 47 ohm resistors if my BMP didn't have enough "kick".
cheers

[Meanderthal]

 I have built 2 of these(and owned several more!), and Have to agree with Mark. Both (well all) sounded different. One was instant Sabbath- a real monster for palm mute stuff. Very much a distortion. The other was all "American Woman" sounding but not very interesting on chords. Very much a fuzz. Both perfed. Neither one did that "Hendrix" out of control kind of thing. I think one of the differences between my builds and commercial ones is that I used all poly film caps, and the commercial ones used ceramic(disks for old, dipped for new). The advice is usually to avoid ceramic caps, but I suspect in the case of a bmp the ceramics may be preferable... All of the commercial ones did the "Super Hendrix" stiff in their own way. By "Hendrix" I may mean the artifacts you mentioned.  Not sure, but that's what both my builds were missing.
Wouldn't you k now, someone bugged me every day until I sold him the "fuzz" one. Now I regret it, I may never get that super smooth "creamy" fuzz sound again.(don't ya just love the descriptions?) Each bmp is an individual, with its own personality! And yet, as different as they are from each other, they all have an indescribable component to their sound that instantly identifies them as a BMP. Call it the wool or something, I don't have words to express myself here...
The Distortion one was 5089's, the Fuzz one was 5133's, minor differences otherwise.

[alfafalfa]

Reading these replies about fx pedals sounding different , well I completely agree !!
After having built about fifteen pedals of which 7 distortion boxes , a few Ts clone , 3 bsiab's and some other pedals I now know the use of certain caps is of vital importance for the sound you want.
In my BSIAB's, ceramic caps gave a more grinding sound and sometimes this is preferable to a smoother sound. In another one I used styroflex caps and this sound is more flutelike in the upper regions. But the "better" caps gave also more bass !!
So I suggest keep experimenting not only with different transistors or fets but certainly tr y diffrent caps.
It makes a world of difference .

Alfalfa

[Mark Hammer]

I think you may want to actually measure the value of the caps involved before attributing things to the type.

A common error is to grab parts out of a bin that have the same nominal value (say, .01uf) and assume that any resulting sonic differences must be because of the material/composition of the cap because, after all, the value is the same, right?  Wrong.  Unless you spend large sums of money, tolerances on caps are much wider than those on resistors.  Consequently, while you may think that the sonic difference between a ceramic and plastic .01uf cap is because one is plastic and the other ceramic, you first have to rule out the possibility that the one is really .0089uf and the other is .0124uf.  That kind of stuff happens, and if often where rumours and legends start.

The sonic quality of a great many distortion units is heavily iinfluenced by how much bass they let in and how much treble they let out.  Variations in actual cap values can produce such tone-shaping differences, despite the fact that it says the same thing on the component.

[Meanderthal]

 While I agree about the tolerance issue I tend to disagree about capacitor type. Ceramic capacitors can induce distortion and harmonics all by themselves. This is measurable.
At least according to this:

http://www.diyaudio.com/forums/showthread/t-5107.html

With the cumulative effect of the numerous voicing caps in a bmp circuit this should become very noticable.

But it could possibly be misinformation, however many people report  exactly the same thing in layman's terms by HEARING a huge difference.

I also once saw a page where a guy used graphs and charts to show the measurable differences between ceramic and most other types. Ceramics came up with completely different "curves". I tried, but can't find that page now. I know I should back up what I say with evidence and all...

But my point is that this is more than just mythology- the differences are measurable and repeatable. If you can measure the differences you should also be able to hear a difference.

Also, why even bother with poly and metal and paper/oil caps if ceramic are so much cheaper and the only real difference is value/tolerance?

[Meanderthal]

Found it! :

http://members.aol.com/sbench102/caps.html

[petemoore]

Switching out the transistors did not do too much.  I think I have 5088' in there now.
  I've read this elsewhere, 2n3904's aren't enough gain, anything 2n5088 or 5089 should supply enough gain.
   One thing that I did do that seemed to get me closer was change out the Sustain pot. The one I had on there measured at only 84k Ohms.  I went and slapped in a 500k.  Does the extra 400k do anything?
  Both values will divide like volume pot and allow 'sustain' to be controlled [on the BMP the name 'sustain' seems applicable IMO].
  Being a fixed resistance between signal path and ground, this pots wafer shunts some signal to ground.
  Smaller resistances will allow more signal to be shunted to ground.
  Not surprizing that 500k pot allows a bit more signal through,

[petemoore]

  I re-opened the BMP today a few times..good thing too.
  I did "Yun's mod" to Q's 1 and 2 emitters to ground. 'opened up' is correct.
  A little cap to ground at Q1's output, switched...
  Q1 was a Ge, but I guessed the weakness I heard was it's position, I swapped that with Q2 so now I have
  Q1 is 5088
  Q2 is an NPN Ge I got from Aron
  Q3 is 5088
  Q4 is 5089
  This BMP Morphed into a real burner compared to what it was doing yesterday..
  Oh...and added an LED indicator...
  Tone knob is slightly elevated, I can turn that with my foot for a bit more bite and boost during solo's...and mahn does it 'does' solos well..

[Meanderthal]

 Was that Ge tranny an OC140? I bought 10 of those and never used any... they just sit in a drawer...

Thanks for sharing the info on the mods!

[bdevlin]

I tried going with 50 Ohm resistors from Q1 and Q2 emitters and then even just tried shorting them.  Neither made a noticable change.  Definitely not worth trying if you are expecting a dramatic change.  Just wanted to point this out for future builders.  Overall I am happy with the pedal.