stupid big muff trick

[pinkjimiphoton]

hey, if you've tried bypassing the tone stack and didn't like the volume/mudd increase, try using a switch and say, a 4.7m resistor in parallel with the bypass...

adds a huge squishy gargantuan creamy sustain that gets brighter as it breaks up and is stupidly phat. the tone control still works either way (if ya just short around it with a switch) tho one way it works less... more like a notch for the sustain. when in bypass, you get a heavily distorted dry signal padded down some in parallel with the tone control, which makes it more "80's" sounding to my ear. antiparallel diodes between center pole and resistor yielded some very interesting results too. i tried 1n4001's and felt a little... ummm... wiggle..very hendrixy long blooming distortion, blooming into pure noise... be still my heart...

not gonna keep it i don't think cuz i don't feel like wasting the switch, but the tone bypass thing is kinda cool at some settings. the parallel distortion and tone tho subtle is WAY more metallic.

anyways, just results of some experimenting on a ram's head style bmp i built yesterday...

using darlington for the output stage, mpsa13

using germ npn's for the clipping stages (with my noise reduction mod, a ge 1n34a in parallel with d4... knocks out most of the "ocean")

still undecided on q1... leaning towards a really low gain bc108, hfe about 60... tho the bc547 hfe 360 sounds pretty good, too..

asym clipping on stage 3 with 1n914/4148

changed the input resistor to a voltage divider, 4.7m to ground and 15k instead of the 33k stock. seems to make it play better with the guitar knobs.

dunno if i'll keep the tone bypass.. almost did a double tone wicker, i have some center off  3p3t toggles... put 470p on side a of each switch and maybe a 100p on the other, tie the free ends of the caps to the pcb, and connect each to the middle but i figured it would be a lot more noise than it was worth... would have stock bmp, tone wicked, and slightly brighter (or darker, depending on the cap size of course) at the flick of a switch.

i also added a pretty standard power supply, polarity protection.. surprisingly, adding a 100r resistor in line with v+ was enough to prevent the circuit from working. so i took it out.

anyways, just some ideas, if'n you gets bored!

[bwanasonic]

I have three OSHpark BMP boards. I'm still finishing the first "stock" triangle version, and if my layout works I'll try some these ideas on the next two.

[pinkjimiphoton]

kerry,
breadboard it first.. like, you can pop the boards, but don't pop where the mods will connect, run leads to your breadboard so you don't have to commit.

i ended up doing away with the tone bypass.. i already have enough loud sludgy fuzzes, and the difference was so extreme in volume/mud  i said screw it.

i kept the power supply filter/polarity protection and assym clipping on stage three (and my noise reduction mod)  and other than that it's within a 10% tolerance of whatever was listed for the rams head version.

the 15k input resistor opened it up some, it's not as dark as the 33k, AND the guitar cleans up better. i think the 15k is great for humbuckers, bit the 33k is better for say a strat with single coils.

for transistors i decided the tonal advantage of the germanium wasn't all that important in this circuit (sounded nice tho) and went wit two bc547's for stage one and two, hfe about 400 and two mpsa13's with gains off my meter's charts. i gotta play with it some to make it a little less hissy, but man,, it sounds great.. used it live last nite and really enjoyed it on the floyd tunes.

[jonnyeye]

I built a muff with Mark Hammer's modded Shin-Ei FY-2 scoop control in place of the stock tone control; it sounds great.  Another option.

[pinkjimiphoton]

i just finished drilling another hole, and adding a midrange control.. there's a 33k resistor to ground in the tone stack in parallel with a .004(7, in mine) cap. what i did after a little experimentation (cuz i don't care for having to unsolder vero, sometimes it gets unstable after a while.... i think melting plastic pollutes the joint and makes a weak node all too easily...)
i took a 10k resistor to the wiper of a 100k pot and connected the free end of the resistor to pin 3 (i think... pins facing right from the back of the pot) of the tone pot, and  pin 3 of the 100k to ground. easy beazy.

instant midrange cut/boost control without having to desolder anything. you can go up to 1meg if you want to on the midrange control and get some serious girth, but it's harder to get as good a sweep that's really useful.. 100k works really well. the 10k resistor sets the filter where with the knob all the way to the left it's very scooped and earwiggy, and to the right, "boosted" somewhat from the stock muff.. it's interactive with the tone control, almost like the they are verniers for each other.. if ya start with both half up, sweep the tone knob to your preferred setting and set your volume so it's good, then sweep the midrange. all the way down makes for a fairly decent metal tone, and all the way up gets nice and phat.. you can dial in that cello/violin sweetness. i tried it with my single coil'd black n nekkid strat and my 335 and i could dial in some nice sweetness on either guitar with just the mid sweep. i'm digging it..
the lowered input impedance seems to open up some more high end dynamics, especially at different settings  of the mid and tone control. and ya can do it to pretty much any muff without having to molest the circuit.

i suspect ohm's law is at work here <g>, but as it's a moving target i cower in fear at the understanding of it.. i just acknowledge that it works. i figured 33k was the original resistor... so 100 divided by 3 is 33....  that would give me the original value and less, or more, depending on how the pot was turned. like i said i can't explain the math, but it lets ya i think get the original value as well as more, or less resistance, giving you more or less mids. i found that at about 3k it seemed to hit cutoff and was very bright by trying a pot wired in and sweeping it.. i tried 10k and it seemed like a good value for the top range of the control and left it at that.

i am REALLY diggin it. i can dial in whatever amount of filth or sweetness i need.  if ya use a dual concentric 100k pot, you can mod your muff without even making any holes.

highly reccomend the midrange control.

if you wanna do it right, take out the 33k resistor and put a 50k pot there. will probably still need a series resistance to keep it from reaching cutoff.

but i think the parallel thing sounds better.. the sweep of the pot is weird, but very nice and useful.

if ya breadboard this, somewhere in the future .... give it a try.