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Which way is right?
MUFF WIGGLER Forum Index -> Guitars, Basses, Amps & FX  
Author Which way is right?
insomniyack
I'm using a Kurzweil Rumour reverb unit on one of the auxiliary sends on my analog mixer. There's a switch on the back of the unit for -10 or +4 and in the one mode I hear much more hiss and white noise but the sound is louder. I switch it the opposite way and it's about the same volume with less hiss...this is the way it should be set correct? The more white noise version would be the WRONG setting right?
Scottzilla
Prosumer/Pro gear is usually +4. You're going to compensate for whichever you choose with the knobs on your mixer though. +4 *should* give you a hotter signal compared to the hiss, so that when you turn down the gain on your mixer input you have normal sound but less noise.
insomniyack
Sorry but I'm still confused. When I turn the volume to max on the mixer I get a hiss from the effect channel and it's not a bad channel...I've already tried that. So I tried switching the +4/-10 switch on the back of the unit and suddenly most of the hiss went away but the volume did drop a little. HOWEVER if I turn up the volume on the processor past the 0dB point it's louder but doesn't seem to hiss as much as it being switched the other way.

The switch is on the back of the unit and I can't see if I have it on +4 or -10 but I know that by switching it the hiss has lessened but the signal has gotten a little quieter too.

So do I use the quieter mode and turn up the gain or do I switch it to the louder mode and bring down the volume on the mixer channel?


Ugh...I hate hiss!
insomniyack
Anybody have this unit that can see the back to see which one I have it set to? It seems to do quite a volume drop when I switch it but so much less noise but it's in a rack where I can't see the back.

Anybody know which way is which on the switch? I can't seem to find any pictures online that you can actually see it.
Pockets McCoy
I checked the manual, you're at +4db when it's switched to the right (well, switched to what would be your left if you're facing the front of the unit, but the right if you're facing the back). -10db means unity gain, assuming the input signal is also -10db. Same story with +4db, unity assuming an input of +4db. Feeding a -10db signal to a +4db input will result in a volume drop, and +4db into a -10db input will result in positive gain.

The switch on the unit is tied to the analog output, which is being fed to the aux. return on your mixer. It sounds likely that the mixer's expecting a -10db signal (you might want to check if there's a switch on it too, if you're not sure), meaning that the Rumour switched to -10db is sending it the signal the mixer is expecting. Switching the output to +4db (obviously) boosts the output level up to what other +4db gear is expecting. It sounds like your mixer is built to work with -10db signals, so when you're using the aux. send/return, here's what's happening:

-10db aux. send to Rumour input gets processed and then boosted up to +4db levels at the Rumour's output, which is feeding the mixer's -10db aux. return and amplifying any noise present because the signal path is set up for positive gain at the output of the Rumour in this particular configuration.

So to sum it all up, the less hissy way is the right way. For maximum signal levels and the best signal-to-noise ratio possible, make sure you've got everything gain-staged correctly. You may already be very well aware of this, but just in case you or anyone else reading this thread isn't, set the output of everything as high as it'll go without clipping the input of the next device in the chain. Basically, keep your outputs as hot as you can and your inputs as attenuated as necessary to keep your hot-as-satan's-testicles signals at reasonable listening levels. thumbs up
insomniyack
Thanks!! It sounds much better that way!!
insomniyack
One additional question...

Should the input gain be at zero (typically) or should it be turned up past that? Thinking that gain + any amount would be boosting it up too much and adding hiss but maybe instead the gain is like a volume and I should have it higher than zero to get a strong signal.

What do you think?


(This all began cause I was muting channels and heard a reasonable amount of hiss on the Rumour and figured maybe I had something set wrong)
Pockets McCoy
You've basically got it figured out. The input gain control (as opposed to input level or something like that) on most gear is a bit of a double-edged sword. From nothing to 0db it acts as an attenuator, and from 0db onwards it acts as an amplifier; 0db is right in the middle, unity gain, the neutral point between attenuation and amplification. The amplification past 0db is provided to boost lower-level input signals up to the optimal level for use with the gear in question, but it's incredibly likely that the mixer send outputs at a level in the range of what the Rumour's looking for, so there should be very little gain necessary at the input, if any at all.

Maybe I'll revise what I said in the last post...rather than "set your outputs high and your inputs low", let's go with "keep your inputs at unity gain or lower (unless your input actually requires pre-amplification to get it up to the proper level for the device, but pre-amping should only happen once in the chain unless there's a level drop somewhere along the line or you're deliberately trying to introduce distortion) and your outputs at unity gain (or as high as they'll go if they're not as hot as unity in your chain, and that would be a case where the greater-than-unity input gain control would come into play).

Happy gain-staging! The Chewbacca Defense
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