DIY test tone generator

[PaulRich]

Hi, Ive been thinking about picking up a function generator
However, I was wondering in the meantime if I could use my Novation bass station to create a sine or square wave test tone to use on my audio circuits
I was thinking about using an mic cable, with one core going to a probe and one core going to a croc clip as a ground
Will this work or would it load the synth in some way?
Also how about using a software generator in my computer then having the same cable coming out of my soundcard?
Thanks
Paul

[James Perrett]

I used to use the self resonating filter on my Juno to generate sinewave test tones. You could almost certainly do something similar on the Bass Station although I don't know if the filter self resonates enough to generate sine waves so you may be restricted to using the waveforms supplied by the oscillators.

As you suggest, you could also use a computer to do this.

If you are using this to inject signals into an unknown circuit then you should use a resistor in series with the output to avoid damage.

Cheers

James.

[PaulRich]

Cool, thanks K=James
COuld I just put the resistor into the cable, and if so what value?
Thanks
Paul

[ef37a]

Most sequencers have a tone generator in them including the free Audacity.

Word of caution. It is all too easy to get "deaf" to a pure tone and find an amp smoking or a tweeter o/c!

Dave.

[Martin Walker]

Indeed - do be careful with continuous test tones. I once burned out an expensive ATC woofer/midrange unit doing this!

Martin

[Adam Inglis]

Indeed - do be careful with continuous test tones. I once burned out an expensive ATC woofer/midrange unit doing this!

Martin

Why does this happen?

[ef37a]

Morning Adam,

At least a couple of reasons. We are very insensitive to very low and very high frequencies, below say 100Hz and above 8-10kHz (pretty much doesn't exist for me at all now!). Plus, LF sine will be heard in one place in a room and almost not at all a few feet away. Thus you crank things up to hear it. Woops! no cone!
HF is very directional and if you are not on axis, again, w.t.f?...crank...smoke! That's transducers.....

Amplifiers: Despite their paper specifications (and the B silly "rms"watts!) many* will not handle extended sine testing at their rated output (whatever you work THAT out to be!). Then again a power amp will be connected to a dummy load because even a few tens of milliwatts at 1kHz is excruciating, so unless you slap a 'scope on the output you won't know when you are overdriving or driving for too long.

Finally, as per my original statement, you quickly "learn" to ignore pure tone and the crank it reflex kicks in once more!

*Very high spec' "pro" amps, Crown come to mind, are virtually indescructable but do not take this for granted with other designs no matter what their tweakybeardy, "Hi End" credentials.

Dave (aka Cynical Old Sod, but I've binnned me share of 2N3055's Ah tell thee!)