I Did Something Bad

If they were active speakers then you are more likely to have damaged either the Pre-Amp in the speakers (the thing the gain control controls) or the mixer..

Does the interference stay if you bypass the mixer?

Active speakers have limiters in for this reason.. The same reason that high end power-amps also have limiters on them..

bob6397

Stick a signal too hot through anything and you’ll damage it..

BTW, Balanced vs unbalanced cables has nothing to do with how loud a signal you run through them.. Its to do with electromagnetic interference and how it gets rid of it..

bob6397

It might be worth getting a decent electrician to take a look (unless the speakers are still under warranty? The warranty probably won’t cover this but it will be invalidated if someone they don’t know opens them up…

It will probably just be a slightly damaged wire on the amp or the like. If the cones are still working then you haven’t blown them..

bob6397

So.. Gain structure..

0dB is the point at which the pre-amp is neither adding nor taking away any signal. Meaning that it leaves it untouched as it flows through. It is identical on the way in to the way out.

On some (cheaper/Less professional) equipment, Sometimes the point at which no sound is let through is labelled as 0. This can be correct – as long as it isn’t labelled as being in dB. This point measured in dB is actually “-Infinity”. (The way this works is by using a resistor to stop the signal flow). Most gain controls have an indication of where “0dB” actually is however..

About the signal – if you have a stereo signal coming out of the R1, then the Left signal is not necessarily the same as the Right. What comes out of each depends on the mixing engineer for the record. Ever listened to old 60’s recordings through a stereo setup? And heard how some instruments are only in one ear and other just in the other ear? That’s because of what is called panning. Back then, they didn’t have the tech to be able to put audio in both channels at once so you either had a completely mono recording or completely stereo. Nowadays, we can do that but quite often panning is applied to open up the soundstage of the track..

Basically – the mixing engineers use the stereo signal to place instruments in between your ears. This means that you don’t necessarily have the same signal going to both speakers at the same time.

bob6397

Just so we are clear, if you are using MIC channels on a mixer running a LINE signal through them, you are bound to have problems as the input signal for the pre-amps is way too hot, even with the gains practically closed.

The mic preamps are there only for MIC pre-amping. If you use the line in input on a mixer channel it will normally bypass the preamp and go straight to gain then the rest of the chain.

Clearly you can, as suggested by others, isolate the problem by taking a clean sound source (an iPhone would do), inputting it straight into a speaker (active speakers should let you do that) and checking if the noise is there. If not move to the next point by injecting the mixer in the chain. Same thing, use a line input on the mixer, set everything to 0, channel gain (if available) to 0dB, channel fader to 0dB then slowly increase the master level.
Etc. You get the drift.

Hearing this, there is a fair chance that the high end circuitry or the high end speaker itself suffered. If this is the case, the first test should reveal this.

As far as a faulty cable goes, I doubt that is the reason based on the story you told us.

Got lots more to say on the subject but not the energy for all that typing now 🙂