Help with guitar pedal...how to mod it for bass?
 

Hi and sorry for my english. I have build 2 Dr Boogey pedals for my friends guitarist. I like sound of this pedal and have parts for one more. So wana build one for me, but im playin bass guitar. Can u help me what mods i need to runing pedal with my bass? Im beginer in electronics, but can try. Maybe can change some caps and resistors in scheme? Use gaussmarkov sheme, and playing PJ passive instrument.
Thanks!

More info on the pedals you're building please.

Im sorry. Here is pedal i build
http://gaussmarkov.net/wordpress/circuits/dr-boogey/
There is a schematic, layout, pcb. I just make pcb, solder elements, bias fets and pedal running without problems. I build only this pedal, twice, for my friends guitarist. I havent nessesery knowledge to modify this pedal for bass guitar, but like sound and wana make one for me, but moded for bass. Maybe must change caps in tone stack, but search in google and cant find solution. So if u can help me what part to replace ill be gratefull.
Sorry again for my bad english. Sometimes i use google translator.
Thanks

i'm not sure about the details of this particular pedal, but any guitar pedal will work on bass. generally, the main problem is that guitar pedals don't keep the low end that we need on bass.

you could add a blend knob so that you can have a mix of the effected sound and the clean sound (with good low end).

hopefully the effect gurus will have more specifically helpful info.

Yes,its work good with my bass,but no lows i need, and cant distorted as bass disters. But i like sound and hope i can find help here
Thanks

The easiest thing to do would be drop all the tone stuff by an octave. Doubling the values of any Capacitors in the tone sections could very well do that. Without a schematic it's hard to give anything much more specific, though.

If there's a biasing capacitor on the input (one in series, not between the input and ground), halve it. Same on the output.

http://gaussmarkov.net/layouts/drboo/drboo-schem.png
This is schematic. If i understand u right i must double caps 10, 11, 12, (double from 220 to 440pf), but cant understand for biasing caps. Maybe this is c21, or im wrong? And where is output cap, output for every one fet maybe?
Thanks

Double 10, 11, 12, and 13. Those are your EQ/tone style controls, and that change should shift them down an octave to match back up with a bass. There might be benefits to changing a few other caps, but these are the simple and obvious ones to change.

Yes, C21 is the biasing cap. It converts the voltage around ground (both positive and negative voltages) to a signal that will work between 0 and 9V. You can make that one half its current value to allow more low frequencies into the circuit. You may decide you don't want to do that, though, I think distortion sounds better when less low frequency enters the circuit.

actually C21 is the input coupling cap. not the biasing cap. a larger value there allows more bass thru the entire circuit.

Thanks for answers,
When change caps in tonestack what i get? Distortion in low freqs, or tone control good for bass guitar?
Need i change values of pots because of new cap`s values?
Thanks

the pot values remain the same.

Everything is clear on tonestack. But dont know what to do with other caps - to double it, or to halve it, and wich caps
Thanks

Here is a list of caps that are in the signal path, mostly coupling caps. Doubling the value of the caps will allow them to pass more bass signal, but beware, there's a trade-off. Too much bass will make the distortion sound 'flubby', 'muddy' or 'farty'.

C21, C2, C3, C4, C7, C8 are the coupling caps in the signal path.

C1, C6 and C9 are the bias by-pass caps, increasing the value of these will increase the gain of lower frequencies.

Thanks for the quick reply. I will try to increase the value of all its capacitors indicated, but not twice, but a little until I get a satisfactory sound. Sorry for my bad English, but im not wrong, right? Must increase all caps u indicated?
Thanks

I agree, double the caps in the tone stack, and increase the bias caps. I'd try 4.7uF or 10uF for the bias bypass caps.

Making changes should be done one at a time, listening to the differences. There may be a point where increasing the low end might make the effect too farty and flubby. I'd start at C1, then move to C6 and C9, then try increasing the tone stack caps. You may want to keep the treble cap (C10) the same.

You should also use socket for the caps, so you can swap them them until you find the values that work best. I would be interested to hear how this works out for you. Please post your results.

+1. that's what I did with quite a few components (transistors, coupling & tone stack caps, and a few resistors on my Dr. Boogie build:



I didn't like it very much stock with a bass, but after the mods it sounds pretty darn good. ;)

Ill post results, but now have problem, cant find J201 fets. In ebay is full with J201, but from China and dont know is they work corectly (fets).Here in Bulgaria cant find.
johnk_10, are u use J201 in your Boogey? I see your fets is on the sockets, maybe u using other fets or im wrong? And if your PC is ready now can u share values of caps u used?
So sorry for my english
Thanks

i'll look at it tomorrow for the values of the caps, but yes, I used J201's in it. I got about 60 of them from a seller on ebay. tayda electronics also carries them.

Ill be very grateful if u share what elements u used in your Boogey. Of course ill try and other values, but still searchin for fets now