Ruby Amp For Bass and Guitar mod

[Ofek Deitch]

Hi guys,
Is it possible to mod the Ruby Amp's circuit in order to turn it into an amp that supports both guitar and bass guitar?
Is it an easy cap switching mod, or is it gonna be a little more complicated than that?

Here's the schematic from runoffgroove:



http://www.runoffgroove.com/ruby.html

Thanks!
- Ofek -

[Bill Mountain]

I would up the value of the 47n cap.  The way it's currently set there is a low frequency roll off at around 300Hz.  I would try a 1uF.  That would put the roll off around 15Hz

[jishnudg]

Bill, how does one get around to accurately calculating rolloffs (I'm a complete beginner - - just getting around to learning these things..) and the frequency response of a pedal?

[tubegeek]

f(-3dB) = 1/2πRC

2*3.14*10000 Ohms *4.7e-08 Farads
=0.0029516

1/0.00295
=338.8 Hz

[Gus]

I would try the amp as it is drawn for bass. 

Remember a bass often has a much higher output than a guitar and more lows.

Little amps don't have much headroom.

So the stock high pass might be fine.

[PRR]

I think Gus is saying.... you won't get Chest-Thumping BASS! from a 1-Watt amp (with any practical speaker (but if you have a W-cabinet, try it!)). Considering ear sensitivity at lower levels, you'd best put your power where you can hear it-- the midrange. Even a 42Hz string has 300+Hz overtones, and your ear re-constructs the fundamental from the overtone series. I've followed lots of bass-lines from 300Hz speaker.

Though I sure would want to try 0.1uFd or 0.2uFd at the input, and 470uFd or 1000uFd at the output. Cap at pin 7 really wants to be bigger if only to suck-up power supply crap; 10uFd is reasonable.

But in the end, unless you have a quiet room and a BIG speaker, 300Hz bass-cut may be the most fun you can get for your dollar.