The 10ohm resistor matches the resistance/impedance of the speaker that has been removed. All you need to know is that without it the sound may be distorted. In some cases it will work fine without. It’s a case by case basis. If it’s distorted, add a 10ohm resistor and it will probably be fixed.
will this modification give me line-level output? I have a Casio SA-65 and I want to drive a fuzz with it, but signal taken directly from the speaker cable has wrong impedance and doesn’t distort much.
I’m not sure what you mean by “taken directly from the speaker cable”. You mean a cable connected directly to the two leads of the speaker while it is active…? Or from the board after the speaker has been removed? The 8 ohm resistor to ground can be helpful and sometimes a limiter resistor in series will help too. The output to the speaker must be hot enough to drive a speaker. That is a lot more signal than a guitar puts out so this will commonly cause problems with certain un-buffered pedals (which distortion pedals often are. Try taking the signal out BEFORE the transistor. This will give you the pre-amplified signal which might be the perfect level for your fuzz.
So mono jacks DO NOT function as switches? In other words, if I want to have the speaker sounding when no plug is in the jack and not sounding when a plug is inserted I have to use a stereo jack that switches it on and off? or can you do this with a mono jack too?
@KLAN It actually has nothing to do with whether it is stereo or mono. If you want to use a jack as a switch you need a switching jack. These are audio jacks with switches built into them. These are available in mono and stereo.
Hi, I’ve been trying to add a jack output to my coleco talking teacher but I either get sound both from the speakers and the headphone or only one of both works. So I can’t get it that either the headphone works or the speakers.. Any ideas/ help?