Fionn Posted June 21, 2014 Share Posted June 21, 2014 I've got a Marshall Shredmaster, it's a classic old high-gain distortion, made for guitar. It's a great pedal and I very much like the scope and functionality of what it does. However, it wasn't designed for bass, and the inevitable loss of low-end (at most settings) is why I don't use it ... although I would really like to. I was wondering if anyone could recommend a modification that would give me the required bass fat out of this thing? Any help would be most appreciated, although I'm an electronics numpty, so I'll be baffled by talk of capacitor values, etc Marshall Shredmaster Overview... http://www.blamepro.com/marshred.htm Marshall Shredmaster, schematic diagram ... [attachment=165393:zshred.gif] Quote Link to comment Share on other sites More sharing options...
topheteatwo Posted June 21, 2014 Share Posted June 21, 2014 Maybe just an EQ pedal would do to bring out the low end, I've used one on bass before however and I was actually pretty surprised by how well it sounded on it's own. Quote Link to comment Share on other sites More sharing options...
chrismuzz Posted June 21, 2014 Share Posted June 21, 2014 Maybe get one of those bypass looper pedals with a blend knob on it? Maybe even stick an EQ pedal after it in the loop. It would make it incredibly versatile and would save you having to open up the pedal! Quote Link to comment Share on other sites More sharing options...
Fionn Posted June 21, 2014 Author Share Posted June 21, 2014 Thanks guys. I don't want to add anymore pedals though. I just want to mod this one, if possible. Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted June 21, 2014 Share Posted June 21, 2014 The generic mod for increasing bass response on many pedals is to increase the value of the input capacitor. That would be the 10nF capacitor next to the input. You could perhaps start by trying something in the 100s of nF, maybe 220nF like the output capacitor. Be warned this may also change the character of the distortion though. Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 21, 2014 Share Posted June 21, 2014 (edited) [quote name='Beer of the Bass' timestamp='1403374548' post='2482246'] Be warned this may also change the character of the distortion though. [/quote] This is very often the case and in my experience, often for the worse. The design of many guitar pedals is such that they cut a lot of bass - before, during and after distortion to focus the sound in a particular frequency range (the RAT is a good example). Putting more volume in the low end means the pedal is overdriving a lot harder and in the wrong place, so the tone changes. I've modded quite a few pedals to 'improve' bass response by upping cap values in various ways and it's never got me what I liked about the pedal before with more bass - I got a different pedal. YMMV, but I'd really consider a blend pedal. After years of tweaking I mostly use a Turbo RAT and a Boss LS-2. Edited June 21, 2014 by ahpook Quote Link to comment Share on other sites More sharing options...
paul_5 Posted June 21, 2014 Share Posted June 21, 2014 Blend pedal - handful of components and it's real game changer. I recently added a LPF to mine so that just the low frequencies are kept unaffected, and the mids and top get messed up. Score! Quote Link to comment Share on other sites More sharing options...
Fionn Posted June 22, 2014 Author Share Posted June 22, 2014 Could the eq controls (Bass, mid-shape contour, and treble) be tampered with to increase the bottom end? Quote Link to comment Share on other sites More sharing options...
ahpook Posted June 22, 2014 Share Posted June 22, 2014 (edited) [quote name='Fionn' timestamp='1403429731' post='2482524'] Could the eq controls (Bass, mid-shape contour, and treble) be tampered with to increase the bottom end? [/quote] You could revoice the EQ to give more bass, but i'd imagine you'd still have to look at the input and coupling caps as there's a lot of high-pass filtering going on before the tone controls. I'm not saying it's impossible - others may have more luck in tweaking cap values ! Edited June 22, 2014 by ahpook Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted June 22, 2014 Share Posted June 22, 2014 (edited) The tone stack could be worth looking at, and because it comes after the clipping diodes it shouldn't affect the character of the distortion too much. It looks like a standard Marshall/Fender amp type tone stack but with the values scaled down from what you would see in an amp. With that in mind, the 6.8k resistor in between the two 22nF caps is often referred to as the "slope" resistor. Changing the value tilts the response of the tone stack towards the bass or treble. If I've remembered this correctly, reducing the value of the resistor will tilt things towards the bass end. You could try replacing that 6.8k resistor with a 10K preset pot so that you can try different values. Although as ahpook points out, there may not be enough low end getting through for this to give the desired result and a clean blend might get you what you want more effectively. If you've got space inside the box for another pot and you don't mind drilling a hole, you could add a clean blend circuit inside the Shredmaster box with one of these kits: [url="http://shop.pedalparts.co.uk/Blender_-_signal_mixer/p847124_8681943.aspx"]http://shop.pedalpar...24_8681943.aspx[/url] I've used one of these before in another pedal, it works nicely and would save you from having to carry an extra pedal. Of course, if you're feeling frugal you could build a similar circuit on perfboard rather than buying the kit, but the little pot-mounted PCB is tidy and convenient. Edited June 22, 2014 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
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