Advice needed on levels - solo acoustic

Longtallronnie

I played my first solo acoustic gig the other week and had some trouble with overloading the guitar channel. I know where I went wrong but would appreciate some advice on how to avoid it in the future.

I use a looper to layer guitar parts but when I sound checked, I only levelled one layer with my vocals, ensuring a good signal was going into the mixer. Unfortunately when I began looping, this predictably overloaded the signal and caused distortion.

I have the following volume/gain controls in order from guitar to PA:

Guitar volume > looper > channel gain > channel level > mixer master volume > power amp volume.

My question is what is the accepted method of adjusting these controls?

I'm guessing I should adjust the guitar volume to get a good signal into the looper then adjust the channel gain with the max number of loops. Adjust channel level in conjunction with vocals, then master volume into power amp and finally PA volume?

ESBlonde

The chain should be set from source and then on through.
If you want clarity in these devices get a piezo horn from an old Disco/PA cab and wire it to a jack/XLR. The Piezo crystals are there own 'crossover' device so only respond to hi freq which for our purposes is clipping/distortion.
Now plug guitar into the first active device (looper) and the piezo into the output. You should hear nothing until the looper distorts at which point the piexo horn can be heard, back off the level on the looper/guitar whatever until the horn falls silent. You have optimum clean signal/gain set. Add the next active device, and move the piezo to it's output, repeat the process finding the optimum signal to gain at each 'knob'. Finally set the volume for the gig and the amps master volume.
This process used to be used for aligning big PA systems when fancy oscilascopes weren't on site, it's cheap, reliable and road worthy.

Longtallronnie

Cool, cheers for that.

ICBM

A quick rule of thumb in an emergency situation where it's hard to identify where the problem is coming from is to turn the earlier gains down (ie in your case the channel gain and possibly the channel level) and the later ones up (ie the power amp volume and possibly the mixer master volume). This will widen the headroom between the input signal and the maximum power output (which is where clipping will always finally occur if the level is high enough, even if the system is perfectly optimised) - but at the expense of signal-to-noise ratio, ie more hiss and hum.

Ideally you want each stage to have a clipping point *just* above the headroom of the following stage, so you don't get any distortion but the signal is as loud as possible relative to the noise. Easier said than done sometimes though!

Longtallronnie

That's pretty much what I was thinking but hadn't allowed for the overdubbed guitar parts!