Help a noob to design a guitar pedal!

[henrebotha]

(Apologies if this is in the wrong section – I wasn’t quite sure where to put it.)

I am a near-total noob when it comes to the theory and design of circuits, but I know my way around a soldering iron and my lead singer builds robots for a living so I’m pretty sure he can help me out. :P Basically, I want to build a pedal for my electric guitar that houses the following effects, in order:

1. High-pass filter
- Bypass toggle switch
- Around 12 or 24 dB/octave cut
- Internal frequency adjust (trim pot/cap/whatever, range of roughly 20 Hz to 400 Hz)
2. Semi-parametric midrange boost
- Bypass footswitch
- Frequency pot (maybe around 200 Hz to 12 kHz)
- Preset gain (around 6 dB)
3. High shelf boost
- Bypass toggle switch
- Frequency pot (maybe 4 kHz to 12 kHz)
- Preset gain (around 6 dB)
4. Compressor
- Bypass footswitch
- Attack, release, threshold, ratio internal adjustment
- Output gain pot

I’d also like a “master EQ bypass” footswitch that bypasses the HPF, mid boost and high boost all at once.

I’m looking for a relatively simple circuit (so that I can actually build it), but I also want it to sound decent. I’ve got a good amp and a good guitar so it’s not like I need to rely on superb pedals to get a good sound, but I don’t want to build complete junk either. I’ve located good suppliers of electronics components and they sell things like enclosures and footswitches, so all I need now is someone to help me design the actual circuit – in other words, you fine folk.

Before you guys issue the usual warnings against DIY: I live in South Africa, and while electronics components are cheap, guitar pedals are not. The cost for components (including a casing and everything) to build a Boss DS-1 is roughly 1/8th of the retail price to buy one.

So am I totally crazy, or can you guys help me come up with an actual circuit to build?!

Again, I don’t understand circuits very well, so here comes a noob question: can I just build all four of these modules as separate circuits and just connect the output of one to the input of the next? In other words: can I just scour the internet for a HPF, semi-para EQ, high shelf EQ, and compressor, and wire them all together and shove them in a box?

Thanks in advance for any help you guys are willing to give me! I wouldn’t have posted here if the welcome thread didn’t make you lot seem incredibly helpful.

[firechief]

Do you know about these guy's "freestompboxes.org" The are heavily into it.
Perhaps you could identify some existing design's/circuts that claim to do what you need and combine them into one unit. The combining of the individual circuts is something I could help with, but first research each individual function, and see how others have done it.

[neutron7]

For the filter parts, i would get a breadboard and some op amps, and download a copy of TI "filterpro" and try out how some of the different filter types sound to you. the parametric part might be a bit more tricky, try modeling some filters that use 2 resistors of the same value, then you could use a dual gang pot.

for the compressor part, i would look for a clone of a popular one. (just watch out for obsolete/weird Japanese parts) and also have a switch so it can be pre/post filters.

[Cassiel]

DIYstompboxes.com - Index