Author Topic: Is this ShredMaster Correct?  (Read 4253 times)

Phorhas

Is this ShredMaster Correct?
« on: March 28, 2005, 05:20:35 PM »
Hello every body,

Does anyone know if the Marshall ShredMaster schematic found here:

http://users.chariot.net.au/~gmarts/pix/a_msm.gif

is correct?

and BTW, what tapers should the Bass, Treble, and Contur be?
Electron Pusher

cd

Re: Is this ShredMaster Correct?
« Reply #1 on: March 28, 2005, 05:34:18 PM »
Quote from: Phorhas
Hello every body,

Does anyone know if the Marshall ShredMaster schematic found here:

http://users.chariot.net.au/~gmarts/pix/a_msm.gif

is correct?

and BTW, what tapers should the Bass, Treble, and Contur be?


Yup, it's correct.  Tapers lin, log, lin as per the schem.

Phorhas

Is this ShredMaster Correct?
« Reply #2 on: March 28, 2005, 05:49:07 PM »
Thanx a bunch.

The reason I asked for the taper type is because I get a funny "feel" to the pots... oh well... more debugging :)

Again, Thank you.
Electron Pusher

ryanscissorhands

Is this ShredMaster Correct?
« Reply #3 on: March 28, 2005, 10:09:09 PM »
Hey, there. Let me know how your Shredmaster goes. I've wanted to build one for a while, but want to start simpler. In fact, it was one of the pedals that I wanted to build first that got me intereted in DIY'ing.

What layout are you using?

Phorhas

Is this ShredMaster Correct?
« Reply #4 on: March 29, 2005, 12:25:05 PM »
Well, I built it on a breadboard. It sounds really muddy and dull...

I guess it needs some more testings
Electron Pusher

Psych0F0x

Re: Is this ShredMaster Correct?
« Reply #5 on: August 28, 2006, 10:32:23 AM »
Apologies for digging this older topic up but I'd like to know where the TL072s connect here? What goes to which number? Are there PCB's for this schem? TIA

Mark Hammer

Re: Is this ShredMaster Correct?
« Reply #6 on: August 28, 2006, 11:52:33 AM »
I'd old off a bit on that build.  The 2n2/220k network in the feedback look of the op-amp after the tone stack is going to roll off the highs above a rockin' 329hz.  Don't know about your tastes, but that doesn't sound particularly shred-ish to me.  The feedback cap in the last op-amp seems suspect as well.  A 1nf/100k combo gets you a rolloff of 1590hz.  That's a bit better, but not by much.  More appropriate values that may have simply suffered from typos are 220pf (instead of 2n2) and 100pf (instead of 1nf).  These will produce rolloffs at about 3290hz (in 2nd last stage) and 15.9khz (in last stage), something more appropriate to the mission.

Nope, some things look a little suspect there.  The design looks alright in terms of what's connected to what, but the component values seem questionable and unlikely to live up to the what the name implies....not unless the pedal is actually called the "Shredmaster in a large cardboard box stuffed full of pillows".

Psych0F0x

Re: Is this ShredMaster Correct?
« Reply #7 on: August 28, 2006, 03:35:36 PM »
Not really what I meant with my question but thanks anyway.

This one is correct right? http://www.handmades.com.br/media/arquivos/pdf/shredmaster-HM.pdf
I'm getting a lot of parts for other pedals including parts for this one, but I just realised I forgot to order all the resistors  :icon_frown:

Oh well, guess I'll have to go find an electronics store around here.

Mark Hammer

Re: Is this ShredMaster Correct?
« Reply #8 on: August 28, 2006, 04:22:05 PM »
That one seems to have the same strange values that I mentioned about the other posted schematic.  C18 might be correct, but C13 just seems wrong.

Incidentally, looking at the Contour control, it seems like an excellent sort of control to have on many distortions.  C14/C16, and R18/R19 form a wide notch mid-scoop filter that bleeds mids to ground through R23.  As the resistance between C16 and ground increases, the scoop becomes less severe.  At the same time as the resistance to ground through R23 get bigger at one side, the resistance between C15 and ground gets smaller.  When it is small enough, R17 and C15 behave like a 1-pole lowpass filter, bleeding highs to ground.  So, in one direction the Contour control can act like a mid scoop, and make the treble and bass seem more pronounced.  In the other direction, the scoop goes away and the circuit attenuates some of the highs while letting the mids and lows through easily.

I haven't used the Shredmaster, or worked out the math, but it seems like this is an excellent candidate for a very flexible EQ section that accomplishes a number of EQ-ing tasks.  I like those sorts of circuits.  This one looks like it has lots of potential.  I can see it being an exellent addition to just about any of Joe Davisson's high gain pedals.  The parts values seem to need some reworking (R17 seems a little low to do any "rounding" of the tone, 1k is probably better), but it has a lot of promise.

Mihkel

Re: Is this ShredMaster Correct?
« Reply #9 on: August 28, 2006, 04:30:55 PM »
http://img238.imageshack.us/img238/8844/marshredwp5.gif

I used that one and it worked, sounded great.

Psych0F0x

Re: Is this ShredMaster Correct?
« Reply #10 on: August 28, 2006, 05:27:58 PM »
http://img238.imageshack.us/img238/8844/marshredwp5.gif

I used that one and it worked, sounded great.

hm, that one looks almost exactly like the one I posted, same values n such. Now i'm really confused?