Hello all, just got the dev board and registered. Been through a good deal of documentation, but yet to write to the dev board. Need a windows machine for that, I use Linux, but there should be a laptop with a Windows partition on it around here somewhere.
Apart from practicalities I've a Hardware question for the FV-1, but it's pretty much a general question, which would apply to all guitar effects pedals. Part of my problem is to do with the vagueness of the definitions of audio signal levels. Starting at the beginning, instrument level, even if we limit ourselves to electric guitar/Bass, depends on a number of factors. At the lowest signal level is probably single coil pickups, followed by humbuckers and finally active pickup systems. The FV-1 is limited to 3v3 so I'm fairly sure it would have no problem with the first two I'm not sure about active pickups. I don't have anything here to check out, even if I did that'd be a fairly limited sample size.
So FV-1 can more or less do 'instrument level' but if I put a clean boost, overdrive or pre Amp before it in the signal path, or even multiples, which ain't uncommon I think I'd pretty soon hit the 3v3 limit of AVdd. Even worse would be the effects loop of an Amp. In that case the signal has been through the Amp's preamp and is then sent to pedals. In that case we're at the mercy of the Amp's design. There are no rules about the levels in the effects loop, this appears to vary from Amp design to Amp design.
Obviously protection circuits are required on the inputs of the FV-1 I guess a Zenner Diode would do the trick (although as a SW Head I hate zenners as a 3v3 Zenner diode doesn't seem to mean that voltage is limited to 3v3. From my previous encounters it's there abouts, but could be a fair amount above 3v3.
Protection is one thing but the other issue is that if the FV-1 is plugged into the effects loop and clips the signal then the result is a very distorted output from the FV-1. Although the FV-1 has the possibility of adding the 'clipping' diode this will only tell you if there's clipping after the circuit protection. So if you have a zenner in as circuit protection which is clipping you don't know. I can't think of a guitar effects pedal which has a 'clipping LED' so don't know if I'd expect a user to see that and actually know what to do.
I guess the only thing to do is put in a zenner, (if anybody has a recommendation be grateful) and if the signal is clipped it'll sound like shite, which ain't unheard of in the effects loop of an amp.
OK there's not much of a question in the meandering rubber dicking, but I'd appreciate other people thoughts on this topic. I have no solution just let it clip. I guess like any chip the FV-1 has it's limits and if you hit them there's no a lot you can do, apart from hope that the user recognises clipping and can take action. I'd imagine people who use effects loops are aware of the problem, but even if you're 'going in the front of the amp' given multiple boost, overdrive or preamps in the signal path, generally before the reverb, you'd possibly have issues.
Levels, Protection and Effects Loops
Moderator: frank