marshall shredmaster volumeknob works till 9.5 then cuts out

[strassercaster]

hello i just built my first shredmaster. its modified to be a  visual sound Hyde pedal. same exact layout except about ten component  values are slightly different and as per the hyde. all the pots are  100b linear except the treble 20ka log everything works all the tones are there . if the gain is past noon and  i turn the volume all the way to 9.5 and i here a click before ten and it goes too 1 and out of phase all but dead. i tried changing out the pot no difference. im stumped. any advice would be appreciated. thanks  in. advance.its bad to the bone but this is bugging me

[strassercaster]

ok well got home swapped out vol pot tried 100ka and 100kb. discovered it only does it when i have the sharp 100pf /blunt 1N switch on the blunt setting. i replaced switch for cap selection and both caps still does it? gain has to be past 7/8 for this to happen as well. i doubt it will ever be set that high but its driving me crazy

[strassercaster]

on the above schematic the hyde is labeled jekyll.

[strassercaster]

well i talked with some pedal buddies . they seem to think it is oscillating. idk how to fix that ha ha

[Frank_NH]

Wow, what a coincidence.  I just finished a Shredmaster build based on the vero layout here!  I'm not sure why your build is oscillating (I didn't see that with mine - check your circuit for the usual problems), but here is my experience.

[EDIT:  Check your volume pot wiring.  I made a mistake on mine by accident while testing and was seeing the same behavior you report.  Perhaps some wires on your volume pot were switched around?]

I've always wanted to try this circuit out, so I checked the available schematics online and made some initial mods to try to make sure my build wasn't dull due to lack of treble (one of the frequent complaints about Shredmaster clones).  So built it and fired it up and...disappointment!  The overall sound was dull, the tone stack didn't do much of anything(!) and the contour control was way too sensitive.  [EDIT: I found a wiring error - actually the contour control is OK as is, though it does scoop the midrange a lot]
 
What to do?  After probing the circuit for awhile, I realized that the tone controls were the main culprit.  So I fired up my copy of the Duncan Tone Stack calculator and went to work.  With the existing cap and resistor values, there wasn't and treble enhancement, just roll-off.   And the bass control was somewhat ineffective.  After playing around with it, I came of with the following mods to enhance the tone controls (I'll use the VS Jeckyll schematic below as a reference):

* Change C9 from 22 nF to 2.2 nF
* Change R12 from 6.8K to 22K
* Change the Treble pot from B20K to B100K

The other mods I made, based on research, were:

* Change C3 to 470 pF (I don't have a blunt, sharp switch and this value is a good compromise)
* Change C4 from 10 nF to 150 pF (the original value was 2.2 nF based on the schematics).  However, fter playing with it like this, I think it may be a bit trebly, so you may want to increase this to 330 or 470 pF.
* Change the Gain pot to B100K (the Jeckyll already does this, the original Shredmaster was A100K).

One other mod I did was to simplify the network consisting of C6, C15, R7, R8.  You can use a single cap and resistor here (e.g. 68 nF, 8.2K).  I also used some diodes which had forward voltages around 1 V versus 1N914s, but that's a matter of taste.  You could add a diode switch and experiment here.  LEDs would be a nice option.

It would be interesting to try modding the contour notch filter circuit, perhaps reducing the bandwidth of the midrange cut, but I'll save that for another day.  Right now, my modded Shredmaster sounds great!

Let us know if you use any of these mods.  Rock on!



[NOTE:  I found a wiring error in my contour part of the circuit.  The B100K for the contour is fine after all.]

[strassercaster]

thanks for the great tipa. ya i changed about 7-9 components to match the hyde to the tee as best i could.  i replaced the blunt sharp switch and the two components that were on it.that didnt help once i finished painting and boxed it no problem at all  i gues the switch needed to be grounded. it only did it when it was dimed on volume and drive which ill hever do anyway. isnt this a wicked circuit? the way it handles the bass and mid lows is really tight. i havent heard any other pedals do it so well. i like mine with the treble all the way off and the countour all the way off as well.  if you go the other way it sounds like pantera  or metalica i prefer the acdc sound  on the contour. you can put this in front of a solid state amp set clean and BAM instant  MARSHall . the best part is that tight mid and low eq but still a little spongy

[strassercaster]

strange that people feel this lacks treble . i use a 1977 jmp 50watt when i put this in the low input with all tone knobs on the amp at noon its simply amazing to my ears. i turn the treble off  ha ha. i use a strat so i get pleanty of treble already i guess ha ha. . You guys rock thanks for the help

[Frank_NH]

Yeah, the Shredmaster rocks!  One thing I really like about it is the Contour control.  It allows you to dial back the level of mids, which can give you a "cleaner" distortion (if that makes sense).  Very different than a tube screamer.  Anyhow, here's my modded version for anyone who wants to build a vero like mine.  Have fun!  

[strassercaster]

hey thats really cool Frank. i am in love with mine the way it is. however when i get a few few more done i will build a second one and try these mods . This circuit mixed with the hyde mods is awesome. i have a son of hydeon loan  but this is more open and and grainy . less refined as well but that not what i am going far. i do miss some of the compression that a real hyde delivers but thats not up my alley either. sometimes things work out really well . in a sentence what is the overall difference between the hyde/master and your killer mod? the contour all the way one way is acdc the other is pantera . i slam mine all the way acdc ha ha.

[strassercaster]

hmm i changed the 2.2 the other way to a 10nf. i also use the 100pf on the sharp setting. this pedal can get real creamy ha ha