Big Muff / Fuzz Moo tremolo modification issue

[moid]

Hello everyone

Yay, I have a week off work, and in the Spring time a young (well middle aged) man's thoughts turn to... effects pedal construction of course! So I've built a big muff variant (a Moen Fuzz Moo) because the one I own has died and my son loves that one for it's ridiculous sustain so it seemed a good idea and I'd never built a big muff before so why not? I built the stock design and it worked first time amazingly enough. Then before I could box it I thought maybe I should see if there are any easy mods to add to it and I found one that takes one of the switches off the Big Muff Pi Tone Wicker (it's a 2PDT ON/ON/ON that has a mids scoop, mids boost and flat response option). I wired that in and it worked for the mids boost and the flat response, but did nothing for the mids scoop. The capacitor recommended for mids scoop was a 4n7, so I tried smaller values - 3n3, 2n2, 1n and finally dropping all the way down to 470pF - all they seemed to do was make the entire audio spectrum drop in volume, with perhaps the bass being cut a bit more... I could not get a mids scoop to function. Not the end of the world because I'm not bothered by that sort sound (and I have a Boss GE7 I can attach if I really need to scoop mids) but a bit irritating...

So I'm left with two poles of this 2PDT doing nothing, and, like nature, I abhor a vacuum so I thought, I know, lets run some cables from different parts of the circuit to other parts via this switch and see if there are any interesting sounds to be had? I discovered that Tone 2 to the collector of Q3 makes a cool synth drone that can be adjusted to be an octave below whatever note I'm playing, however it never fades away and so is rather annoying after a while. So I skipped that one. Next I hit gold - a pseudo tremolo that is rather good. Connect the Emitter of Q4 to the Collector of Q3 and you've got a pseudo tremolo! It's an interesting one - the attack of each note is unaffected, and then as the note starts to decay the tremolo kicks in and lowers the volume, then rises up and repeats (and being a big muff with a lot of sustain) this process goes on and on for a while The speed of the repeats seems to be determined by the pitch of the note - high notes being much more rapid, and low notes a lot slower. In other words, an excellent addition to any effects pedal. I couldn't work out how to control the depth (putting pots of different sizes into the cable just turned the effect off regardless of size (I tried 1K to 100K). I discovered that if I added a booster pedal before the big muff the increased volume reduced the tremolo effect, so I dropped that idea. Turning the guitar volume down just reduced the volume of the entire signal so wasn't worth trying.

Here's where things start to go wrong. I soldered the respective points on the transistors to the two spare lugs on on 2PDT switch and then connected them together to form a bridge. This worked, but when testing the pedal with the other settings on the switch (mids boost and flat response) they still worked but also had the tremolo effect as well. Bummer. I cannot work out how that happens, because in my mind that should be impossible... anyway I desoldered the cables from the switch and attached them to an SPDT switch (ON/ON) so I was using lugs 1 and 2  (with lug 3 attached to nothing), and lo and behold this works! tremolo when I want it, and none when I don't. Yay.

My simple brain can't work out how this is different to putting the circuit into the 2PDT? I can live with it not doing that if that's the easy solution, but I need to add something to that 2PDT switch with two empty lugs. Anyone have any thoughts? Maybe a low pass circuit so I could make the big muff really soft and woolly?

Here's the original schematic and layout I followed:




I took the 2PDT switch from this layout (connected the same way)


Hope you are all well and surviving being quarantine restrictions.

[duck_arse]

moidys - if this is true:

(it's a 2PDT ON/ON/ON that has a mids scoop, mids boost and flat response option). I wired that in and it worked for the mids boost and the flat response, but did nothing for the mids scoop.

I presume you know that an on-on-on switch has an up and a down, and won't wire correctly upside down.  check your switch.

[moid]

Aloha your duckness

moidys - if this is true:

I presume you know that an on-on-on switch has an up and a down, and won't wire correctly upside down.  check your switch.

You presume that I know what I'm doing, and that I am not, in fact, a conglomerate entity composed of thousands of monkeys all hammering away at an infinite number of components in an attempt to create something that actually works, but is more likely to fail tragically. I appreciate your presumptions about my intellect. I apologize for ruining your preconceived notions of the development of human intelligence in this part of the Northern hemisphere.

I was about to say que? and you is doin' me a confuzzle, when what you said made me look at the switch I installed... in daylight. And if I take my glasses off and squint under sunlight there is a small plate on one side that says ON OFF ON... so, let me guess, I put the wrong switch in? I thought I had bought ON-ON-ON switches but it looks like I didn't Bummer. That *might* explain the lack of functionality. Having said that I've no idea whether I should be using ON-OFF-ON or ON-ON-ON switches for this circuit. The vero diagram does not say. Do I need to buy more switches?* Also ON-OFF-ON appear to be available in type 1 and 2 (type 2 cost three times as much!).

From there I also looked at some wiring diagrams for 2PDT switches... which makes me think that I really don't know what I'm doing with that switch (Or for that matter how the switch in the diagram I was working from actually works in the first place!) How does one tell which way up the switch is? I can't see any tiny marks on the surface...oh @#$% there is a small white dot on one face of the switch, would that denote UP?

Here's a picture of what I think of as the bottom of the switch (with 10nF) cap attached, modelled by my own fair hands:


It does have a dot on it that I assumed was just a mold mark... but is perhaps something more important... like UP... or DOWN... or SHAKE IT ALL AROUND?

and also just noticed (but not visible in this picture because of fat fingers in the way) - there is a slot cut into the metal shaft of the switch, facing the same direction as the white dot, and from looking at this datasheet,  I guess that is up? http://www.fk-industrie.de/downloads/T80Ts.pdf

And here's a lovely photo of the switch in its current state, this time in focus (just for kicks of course):



That's a 10nF capacitor at the (what I was thinking of) bottom of the switch (but which is probably the top) as shown in the vero diagram I took it from, and this part works - flip the switch up (away from) the 10nF Capacitor and the mids get louder. If I put the switch in the middle position nothing changes on the circuit (good), but if if I switch the switch down (so nearer the 10nF) whatever is in the top two lugs appears to do not much - putting capacitors across those two empty lugs like it shows in the EHX Civil War Big Muff vero layout (it's a 4n7) just gives me an overall volume drop, not a mid scoop... so I'm thinking I've not read the diagram correctly... merde merde merde as they say in London, Manchester and some parts of Basingstoke**.

It now looks like middle position is the scooped sound, and the top position is flat... hmmm they both sounded the same to me. So perhaps that's why changing the capacitor (the 4n7) to something smaller just lowered the volume of all the audio? Should I put a cap across the middle two lugs to make things more scooped? I am most confused, especially when I find wiring diagrams that show that the switch doesn't behave at all like I thought it did... (insert a selection of exotic, but highly offensive oaths from a country of your choice)

Well the switch works in two positions, can I use those last two lugs to do anything with, and if so should I wire things differently? I'd like to send the spare two lugs out to a passive RC lowpass filter (a 1M pot and a 1NF cap) which would allow me to remove a lot of high end and leave me with just bass sounds and a bit of high frequencies depending on where the 1M pot is turned to. Mind you, I'd also like to win the lottery, but it looks like neither of these two aims is likely at the moment.

I think I'll go and build a new planter for my son's tomato plants; planks of wood generally behave themselves in ways that electrical components don't!  Thanks for any advice you can give.



*ahhh if only all of life's problems could be solved by buying more switches...

** the French speaking enclave of Basingstoke of course. I mean you wouldn't expect to hear those tones in the docks, or the Mexican quarter, or the Mongolian campsite and grill would you?

[duck_arse]

strewth. also, strike me pink.

your first post contains no circuit diagram with a switch, so I will not conject as to what or how many it might have or be. circuit diagrams - they're great, aren't they? them and datasheets .....

so. your switch, if it is a [latching both ways] centre-off type, SHOULD have markings on the side plate like ON ON. the presence of the centre position tells you, well, that it is centre off. IF instead, it was an on on on type, it would side plate stamp with ON ON ON, and would have minimum 6 lugs. (if any of the ON stampings were (encased in brackets) it would indicate that position was momentary, sprung-return if you will, but that is not the topic du jour, pierre.)

and data sheets - if you skip ahead to your quoted switch one, to page A-16, it shows the orientation of the switch, with regard to the uppedness and the downingswise, AND the keyway. which you spotted. and which on near any other switch has no meaning [of use in this topic].

it seems "T-80" is the common standard for these types of toggles. your manuf calls the on on on type "3-way toggles". which is nice.

any clearer? and yes, buying switches does indeed solve all the problems.

[moid]

Curiouser and curiouser!' cried Alice (she was so much surprised, that for the moment she quite forgot how to speak good English)

This evening I bolted the low pass RC circuit to the spare two lugs and hey presto, it works! 1nF was too subtle so I went up to 3.3nF with a 1M log pot. The only issue is that the sweep of the pot from off to on is quite narrow; about a quarter of the turn (I tried a lin pot and the travel seemed even narrower). Perhaps that is one of the issues with a passive low pass filter? That and the slope of the effect is rather gentle; presumably to get a steeper slope to the effect (and therefore a more pronounced drop in volume of high frequencies) I would need some sort of powered filter or something more complex? Anyway with the other switch that adds the tremolo on, I can now get a very synthy quavering sound that is very un big muff, but really interesting! Tomorrow I'll solder this lot properly and get it into a box!

Thanks for your help!

[moid]

Well surprise, surprise, the beast actually works! Downsides are the low pass filter is no way near as fabulous as I would like it; it clearly should be a powered filter of some kind with a steeper slope and maybe some resonance. The rest works fine, and the pseudo tremolo is fun Which is more than can be said for my fingers - I was trying to get access to a panel in our dishwasher (which conveniently decided to spring a leak last night / early this morning across the kitchen floor) when I slid the inspection panel off to discover is it razor sharp thin metal that slices through the pads of your fingers really easily... so no playing guitar for a few days! A curse on anyone who designs sheet metal panels without rounded off edges.

Edit I forgot to say I switch the pot and capacitor on the low pass filter to a 100K log and a 15nF cap and got the same frequency range but with a sweep on the pot that is actually useful!

[thetragichero]

your method of tinkering with the circuit reminded me of many many moons ago before i even got into pedals and amps: circuit-bending children's toys. basically i would purchase electronic children's toys and poke around inside seeing what cool sounds would be created shorting various parts in the circuit together. find a cool sound? run an spst switch between those points and mount it to the case. some spots would sound neat being touched by human skin. those I'd run a bolt to the case and solder to the bolt. obv was really popular in high school tearing apart children's toys to turn into noise makers for weird music

[moid]

I think tinkering is a polite term for blundering around with crocodile clips on the ends of cables, but sometimes it comes up with some lovely results (sometimes it kills pedals, but I have since learned not to connect 9v power supplies with digital ICs whoops).

If it helps anyone here's a layout of what I did should you wish to do the same.



I hope to get my son to play a demo of this, and if so that will appear too