V1 Big Muff Q ...

[mikeC]

HA !!!!!!!!!!

i don't know exactly what happened but now Q2:  B .6v, E 10mv, C 3.7v

FRIPP in a box !!!! 200 lb violin and all that !!!!

how do i figure out what was/is intermittent about this thing?

[thermionix]

Try lightly wiggling each component lead with a chopstick or similar.  If you can't find it, re-solder everything associated with Q2.

[Marcos - Munky]

Nice thing you got it working. I believe it's a bad solder point, so do as thermionix said and resolder everything connected to Q2.

On the audio probe, it's exactly like you've descripted. It's easier than it looks, but you won't need to do it with the big muff. Here's a video on how to make one: https://www.youtube.com/watch?v=jWvIfDSxbIk. It's just an idea, you can work with something similar. Inject signal on the input and check the first part on the signal path (just check the schematic, you'll need to check almost everything that isn't connected to ground or V+). Got sound? Nice, move to the next part. Don't get sound? Then you found where's the problem, so you need to check the parts around that point. As a signal generator, you can just use your guitar, but you need to hit the strings and check the parts while the strings are vibrating - so it's a nice idea to build a simple signal generator.

[antonis]

After your official accolade as verified troubleshooter, mikeC, it should be a good idea to re-solder the whole PCB, including wiring, for a long healthy life of your BMπ...

[mikeC]

thank you, fellas'!

that was super fun and i'm sure i learned some things ; )
i reflowed all joints involved w Q2 and muff seems pretty sturdy now ...

this thing has SO. MUCH. GAIN. (and noise too!) ... it's actually a little ridiculous. notes sustain for dayyyyyyyyyyyyyyyyyyyyyyyS

i'm going to poke around and see best way to lower gain a little bit. at lowest "sustain" it'd be nice to have merely overdrive in lieu of flame thrower.

thank you all again and c'mon spring! (he says as Nor' Easter #4 is about to dump another foot of snow on him)
mike

[thermionix]

I don't know if the BMP is really capable of a nice mild overdrive sound.  Too many gain stages, with too many clippers.  Is this an actual vintage triangle Muff?  If so, it's probably worth too much money to modify in any significant way, IMHO.

[mikeC]

it'a a Guild Foxey Lady ..
you're probably right about not modifying it.
i suspect a modern reproduction would sound as good, be more flexible and quieter ; )
best,
m

[thermionix]

it'a a Guild Foxey Lady ..

Cool!  What transistors are in it, 2N5133s?

i suspect a modern reproduction would sound as good, be more flexible and quieter ; )

Do it.

[mikeC]

SPT 87-103s

[GibsonGM]

it'a a Guild Foxey Lady ..
you're probably right about not modifying it.
i suspect a modern reproduction would sound as good, be more flexible and quieter ; )
best,
m

The 'modern reproduction' that you'll be building, right??

You must live near New England if you're worried about a nor'easter burying you (us) again?   I think it's not going to be as bad as the last couple!

[Mr.Kite]

I don't know if the BMP is really capable of a nice mild overdrive sound.  Too many gain stages, with too many clippers.  Is this an actual vintage triangle Muff?  If so, it's probably worth too much money to modify in any significant way, IMHO.

I agree completely: if you'd like a "MuffDrive", build a Muff Fuzz and leave that vintage pedal alone!



I've just breadboard it and it cleans up like a Fuzz Face and sounds like a low gain\dark-ish Big Muff with the volume full up...

Uh, sorry if it's off topic, but anybody has voltage readings of vintage units? I found a couple of versions and I always end up with ~4.5-5.5v at Q2 collector (which seems fine to me) and it sounds good: a little fuzzier towards 4.5v, more overdrive and less fuzz towards 5.5v...

[antonis]

i'm going to poke around and see best way to lower gain a little bit.

Q1 offers about 13db gain (tonestack "recovery") so by totally omiting it should result in too many "little bits" lowering.. 

For some "little bits", you may try to lower R6/R4 ratio value..
e.g. by reducing R6 to 6k8 - reducing also R7 to 270k for proper bias - you lower gain about 5db (from 13 to 8..)

You may also use a 10k pot instead of R6, leaving bias resistors as they are, for adjustable final gain.. 
(or even better/usable, a 5k pot in series with 4k7 resistor..)