Hi am building a mudbunny and have a few questions while I'm waiting for the PCB
The partlist recommends film capacitors for most of the caps in this build, all I could get from the local supply store was green caps like this (http://www.electronic-life-forms.com/wp-content/uploads/2010/07/Big-circuit-board-with-green-capacitors-150x150.jpg)
but I figured they would be okay didn't have any of the plastic rectangular film ones I see in most Big Muff builds.
Also am putting in a tone bypass switch (like the tone wicker on the new big muffs)
and was also wanting to be able to switch between green russian and triangle and possibly rams head tonestack specs. Since the only differences in the tone stack are two resistor values, could I just use a switch with two sets of 3 terminals to switch between the 3 different modes (russian, tri & rams head)
What's that like a DP3T? Sorry for noobness, I'm sure there's a simpler way than how I'm describing it.
Welcome! A great choice I must say :)
Green film caps will work perfectly fine. People claim to hear differences in using different caps, I've haven't tried yet but nothing that's really gonna change the uniqueness of the circuit.
Here's a thread where I've done a diagram for the tone stack lift. I made a small mistake but if you read the post I noted the corrections. There's also info for a mids knob in there too if your interested.
http://www.madbeanpedals.com/forum/index.php?topic=1872.0
I understand what your saying with the tonestack switch but I can't think of anyway off the top of my head that you could do all three on one switch. There are DPDT ON/ON/ON switches but they still combine the middle with either top lugs or bottom lugs so its not 3 independent choices. Here's what I'm saying..http://3.bp.blogspot.com/_hWtqqQxBsDs/Sctkoll7-tI/AAAAAAAAAFY/V7jHQnasuFA/s400/DPDT_switches.jpg I can think of a way using 2 switches, but honestly I recommend the mids knob as a great mod. It will add tons of versatility by letting you adjust from the scooped mids to flat mids to boosted mids! Along with jumpering the emitter resistors of Q1-Q3 you'll have a tone/gain beast!
Quote from: bigmufffuzzwizz on July 13, 2011, 06:54:00 AM
Welcome! A great choice I must say :)
Green film caps will work perfectly fine. People claim to hear differences in using different caps, I've haven't tried yet but nothing that's really gonna change the uniqueness of the circuit.
Here's a thread where I've done a diagram for the tone stack lift. I made a small mistake but if you read the post I noted the corrections. There's also info for a mids knob in there too if your interested.
http://www.madbeanpedals.com/forum/index.php?topic=1872.0
I understand what your saying with the tonestack switch but I can't think of anyway off the top of my head that you could do all three on one switch. There are DPDT ON/ON/ON switches but they still combine the middle with either top lugs or bottom lugs so its not 3 independent choices. Here's what I'm saying..http://3.bp.blogspot.com/_hWtqqQxBsDs/Sctkoll7-tI/AAAAAAAAAFY/V7jHQnasuFA/s400/DPDT_switches.jpg I can think of a way using 2 switches, but honestly I recommend the mids knob as a great mod. It will add tons of versatility by letting you adjust from the scooped mids to flat mids to boosted mids! Along with jumpering the emitter resistors of Q1-Q3 you'll have a tone/gain beast!
I thought about the mid knob but I really only want two or three subtle differences, a mid knob is just gonna be more tweaking and less playing for me, I might just go with green russian specs and then a different setting with the toggle switch which has a less pronounced mid scoop. I've been playing round with the tonestack calculator program with this anway so will probably just find my two favourite sound before I commit to PCB
I need to play around with that tonestack calc more! I usually just do it by ear. You can easily socket those two spots and have a hay-day trying different values.
I have breadboarded the circuit but am getting just a buzzing sound when the effect is both on and disengaged, LED lights up, but nothing but a loud hum. This is the 2nd time I've breadboarded the circuit and I'm almost certain I've done it right, does this sound like a wiring issue?
More than likely. If it was an open you'd be getting nothing. Can you post some pictures?
that's what I thought, would it be a problem that I followed the GGG schem but am using the madbean wiring diagram? I'll eventually be putting it on a mudbunny PCB anyway.
If it still doesn't work after I've redone the wiring I'll post pics.
Just had a thought, at this stage I'm just wanting to do some component swapping and modding, so could I just hook up input and output with 9v wired in and forget the switch and LED for now just for simplicity, so I'd have an always on circuit?
ok so the input/output/9v idea didn't work, no signal not even hum.
Re-did the madbean wiring, this time grounding the sleeve of the output.
Signal when bypassed AND signal when the switch is pressed, however it doesn't sound much different to the bypassed sound, and fiddling with the pots does nothing, so it seems like either the GGG circuit doesn't like the Madbean wiring, or I've done something wrong with the wiring, although it looks fine to me (albeit a little messy) and I'm certain I did everything right this time.
(http://a1.sphotos.ak.fbcdn.net/hphotos-ak-snc6/283523_1957335608177_1086351958_31821350_5518861_n.jpg)
(http://a7.sphotos.ak.fbcdn.net/hphotos-ak-snc6/284553_1957335968186_1086351958_31821351_3896183_n.jpg)
(http://a3.sphotos.ak.fbcdn.net/hphotos-ak-snc6/281633_1957336568201_1086351958_31821353_6227364_n.jpg)
(http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/282703_1957336688204_1086351958_31821354_329918_n.jpg)
I had the same problem try- standard wiring for madbeanpedals.
It worked for me sound great!
another question while I'm waiting on the PCB how important is the separate part of the circuit (C14,15 D5 etc) It's not on a lot of the other schematics for the muff I've seen, what does that actually do?
Quote from: druz15 on July 24, 2011, 02:25:58 AM
another question while I'm waiting on the PCB how important is the separate part of the circuit (C14,15 D5 etc) It's not on a lot of the other schematics for the muff I've seen, what does that actually do?
Your right, those aren't on all BM schematics. D5 is polarity protection in case you plug in the wrong power, only the diode will blow. I know C14 is for filtering and C15 is probably the same. That would be a good question to ask Mad Bean why he uses those two caps there. :)
well I put them in there anyway, figured why not. Have wired everything up on the PCB, but still getting no signal when effect engaged and no LED lighting up.
I think it may be the way I've wired the power supply up, since I excluded the battery snap I may have connected it so when you plug in the power it just shorts the whole pedal
http://www.beavisaudio.com/techpages/PedalPower/
if you read down a bit it mentions how plugging in the power shorts the battery out, but since there's no battery there I may have made it short out the circuit instead, will have a look and see if reversing the red wires helps
If you have alligator clips try connecting the two positive spots together and see if that gives you signal. Also you could attach the battery positive lug on the power jack to the ring of the input since your not gonna use a battery. Can you verify that your getting 9v into the circuit?
yeah I was right, followed someones advice in the wiring thread about not using battery clip and it's all set. Still had the ring of the input jack wired up.
Is it normal to have weird intermittent signal when the pots aren't in the enclosure?
I was testing it out outside the box but the signal kept breaking up and the controls kept doing weird things, then I screwed the three pots into the enclosure and it goes sweet. I'm guessing they need to be grounded to each other or something.
Sounds really nice with the russian specs, have R18 and 19 socketed, so gonna play around with Rams Head/ Triangle tone stack values also. It'll have a DPDT switch to go between Russian specs and Rams head, and also a SPST between R18 and C11 with ground to cut the tone control altogether
Good work! Glad you got it going. All you had to do was reverse the wire on the power jack?
I find that things do work intermittently when tested outside of an enclosure. It's not always the case but it's quickly solved by moving things around.
I'm confused what you mean by putting a SPST between R18 and C11? Are you not trying to skip the whole tone stack, just the tone control knob?
How does it sound?
didn't really explain it that well. Basically C11 and R18 run from the tone put to ground, and the tone pot bleeds off frequencies to ground. An SPST connecting the ends of C11 and R18 together, with the other lug connected to ground means when the contact is broken, the tone doesn't bleed the frequencies to ground, essentially bypassing the tone control altogether. If done properly, the muff should be boosted slightly, have a fuller sound, and the tone knob should do nothing when turned.
Basically the same idea as the tone switch on the big muff wicker pedal.
Interesting. I always assumed you needed to skip the whole tone network to effectively do a tone bypass. This way is a whole lot easier. I'll have to give that a try!
idea stolen from here basically
http://www.muzique.com/lab/tbypass.htm
except I also have the DPDT switching between different values of R18 & 19, with one lug of the 18 resistors going to the ground switch with C11. Have yet to test it out yet as I'm re-wiring with everything in the enclosure
cool druz... you'll have to bring it to the next gearfest 8)
Now I realize that I wasn't fully bypassing the tone stack with my original attempt. This way is much more straight forward, just lifting that part from ground. I think the only way to do this to a mudbunny/gruntbox would be to actually remove R18/C11 and solder it directly to the toggle switch, is that how you did it? I can't think of any other way since those components other pads are straight to ground.
yeah R18 and C11 directly on one lug of the SPST, wire going to ground pad, wires going from the legs of R18 & C11 to their non-grounded connections on the PCB