Live Sound Question for all of you Signal Path Gurus...

[Gregg Juke]

Hey All,

I'm putting together a pretty complicated DJ rig (I'll try to post some pictures when I'm done re-wiring in a few days), and I had a question (and perhaps several follow-ups) for the TOMB peeps, to wit:

I have two CD players and a bunch of samplers/pads/effects running into a rack (Furman power, some more mix FX, and a DOD compressor), before the mix ultimately exits the rack from compressor outs and goes to the PA (Mackie box head mixer, not a simple power amp; plus, there's quite a bit of sub-mixing going on). I'm planning on doing some more performance-oriented stuff (sampler routines, effects, some live instruments/vox looping, etc.), and sometimes it would be nice to be able to do a hands-free volume fade (for example for a microphone talk-over... I know I could use side-chain ducking, but I hate the sound of ducking, I prefer a simple fade up/talk/fade down). Anyway, I know there are some slight possibilities of problems with mix compression live, but I've been testing it out and it sounds OK, and I don't think I'll have any amp/speaker issues in the long-run (very light compression-- like 3:1 or less). I'd like to put a volume pedal as the last thing in the chain before the PA, so I can accomplish said hands-free fades. I did try that out, and so far it works fine, but there is a significant volume drop, regardless of where I have the volume knob set on the pedal (wide-open or not). So I'll have to increase the volume again with make-up gain to get the system pumping (turn it up either before the pedal or after at the PA amp stage).

Soooo, all of that to say this: Do any of you foresee any issues with impedance, taxing of amp or speakers, or any of that with all of these signal ins and outs and volume stages, plus compression and a volume pedal?? I'm assuming that as long as I gain-stage everything properly, I'll be OK, and so far everything has sounded good in my tests, but are there any facets of Ohm's Law I'm blanking on here? I'm not going to hurt any of the gear this way, right? If I'm doing a wedding, the system may be running continuously for four to six or more hours at a time. Just checking. I think I might have a few more questions, but let's start with this (since in all of the hub-bub I forget whatever else I was going to say)...

GJ

[Snarl 12/8]

You're using a guitar volume pedal on a line level signal? That volume drop tells me there's a mismatch somewhere. You might want to try a reamp into the pedal and then a DI out of the pedal and see how that performs. Or do a DIY volume pedal (or mod) that takes into account the levels and impedences that you're really running at.

[Gregg Juke]

Not a guitar pedal per se Carl; I believe it's a stereo keyboard volume pedal (two-in, two-out, so the mismatch may not be as bad as guitar signal to line level), but your suggestions are exactly what I'm looking for, so thanks and "keep 'em comin'!"

GJ

[Nick Sevilla]

Not a guitar pedal per se Carl; I believe it's a stereo keyboard volume pedal (two-in, two-out, so the mismatch may not be as bad as guitar signal to line level), but your suggestions are exactly what I'm looking for, so thanks and "keep 'em comin'!"

GJ

It is still probably a +10 (250 or 500K pots) pedal.

I'd either get a super cheap Behringer or Mackie 4 or 5 channel mixer.

http://www.mackie.com/products/vlz4-ser ... ct-mixers/

Cheers

[Gregg Juke]

Oh, I've got mixers out the ying-yang, Nick. I'm looking for a foot-controlled/hand's-free solution.

GJ

[Nick Sevilla]

Oh, I've got mixers out the ying-yang, Nick. I'm looking for a foot-controlled/hand's-free solution.

GJ

Then you could modify your stereo pedal for line level signals.

Change out the pots for less resistance ones, 25K for 250k ones, or 50k for 500k ones.
Whichever you find inside the pedal... Long live soldering!

Cheers

[The Scum]

When devices have active, buffered outputs (as almost anything will), the impedance isn't such a problem, as long as it doesn't get too low. It should be able to drive 10K without a problem. And 250K or 500K are smaller loads, so it'd have to work less hard to drive them.

Is the pedal hooked up properly? You haven't transposed the input and output?

I'd sooner suspect that the volume pedal introduces some sort of balanced/unbalanced mismatch. There are times that a balanced output does wacky things if not unbalanced properly.

[Gregg Juke]

Nick-- Great idea if I get gutsy.

Scum-- Pretty sure ins and outs are correct. It's a passive pedal (no power plug or battery, just ins, outs, and pedal). I forget the model number, but it's an old Boss unit.

GJ

[C_R_J]

i am just a bit confused. are you just looking for a way to turn everything down so you can talk over the mic? or am i missing something? i do the same sort of stuff as you do, so im just trying to figure out exactly what your end game is here (ideal situation)

[Gregg Juke]

Yeah CRJ, just looking for a hands-free solution for volume control.

GJ

[Gregg Juke]

PS-- After thinking through this answer a little more, I'd like to know:

a) If anyone has any concerns about using compression live (as described in my original post); I know some soundmen and DJ's use compression, and I have heard others warn strongly against it due to possible damage to speakers and amps. I am talking light compression (3:1) for limiting and a bit of punch.

b) If there might be any real issues (damage to amp and speakers) when using a volume pedal inline (especially if there seems to be an impedance mismatch as described above), or if I should just use it and "turn everything up."

and

c) Is there another/better way to get hands-free volume control than what I'm describing; have I missed anything?

That's what I'm looking for (see a, b, and c above)...

GJ

[Snarl 12/8]

I just lost about a page of ideas for you thanks to a spontaneous reboot after running windows update. Yay, it must be Wednesday!*

I came back because I thought I had a good idea for you. What if you had a continuous sound source (like a simple signal generator, or perhaps a loopback of your program material) going into a simple momentary foot switch and then into the sidechain input of a compressor strapped across your music buss. Then, you could press the pedal, wait a beat, and start talking. You wouldn't have to find the exact right volume with the pedal every time once you had it dialed in. I bet there's some sort of device (probably in the conference, retail, etc. pro-audio world) that is designed to do this without the external sound source, but I can't seem to find it for you.

*I used to fantasize that it would be cool if every time Windows crashed, (this was years ago, when Windows crashed more) someone would come and just pluck a single hair off of Bill Gates' head and/or body. Then, every time you'd see him on TV or in pictures his completely hairless head (and you'd know it was every hair, everywhere) would remind you that you weren't alone with your Microsoft problems. This was when I worked for the government and it dawned on me that you get big problems when the pain of fucking up isn't felt be the people that fucked up.

[Gregg Juke]

Hey Carl,

I love your Bill Gates idea... I wonder how that could be implemented?

Thanks for thinking of the 101 ideas anyway; maybe a few will come back to you.

On the compressor thing, if I read you right, it sounds like a form of ducking. This can be accomplished fairly easily and is used by a lot of mobile DJ's and some radio people; I just hate the sound of ducking and prefer a simple fade-up, fade-down. It always sounds too stilted/abrupt (whatever precipitous adjective you want to throw in there).

GJ

[vvv]

OK, so I'm trippin' here but Snarl's inspired me to be creative (imagine, Snarl, sitting in front of his re-booting computer, dreaming of a plucked and hairless Bill Gates ), but mebbe you could work up a way to use a Theremin as a controller?

Or one of those movement or light-based controllers you see in the tech sections of geek sites?

Or even a touch-screen, perhaps with a fader?

I suppose it would be kinda complicated and require VCA's and mebbe MIDI or some such, but ...

And of course, to be hands-free you'd have to use some other appendage.

Aiighty, where's the black light and fluorescent posters?

[Gregg Juke]

That would be cool, trip-v (just to have more flashing lights). But I'm really looking for hands-free. I know it seems odd, because I'll have sub-mixes (2-4) going into a PA mixer, so I'll have faders and volume controls all around me, but I'm looking for a way to do it while I might be doing something else-- adjusting the mike, holding/moving a cue sheet with names of people in the wedding party or upcoming songs or requests or whatever, fading something up/down, or even doing some more intricate type of "DJ routine" stuff (adding some live percussion, maybe some rhythmic volume cut-offs with my foot while juggling something else; I've got three samplers and some Kaoss pads and outboard effects and other stuff, and I'm trying to keep things interesting as a musician spinning CD's, without going overboard on the effects/mixing techniques). I eventually want to add my drum machine and some synths to be able to switch over to some "live" dance music, so I might be tweaking with my hands when I need to do a fade-- hands-free is the way for me.

Also, anybody who has done a mix under pressure with all kinds of faders and volume knobs around knows that invariably and inevitably, you're going to grab the wrong one. If I have one volume pedal with the whole music mix going through it, I've got a fail-safe right under to my feet...

GJ