Recommended strategy for using two mixers?

LesWilson

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Mar 2, 2012
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South Florida, USA
My private K-12 school employer's venue has a 15 year old Allen and Heath GL2800-48 channel mixer. It's been losing channels and we're down to 38. I purchased a QU-16 for our musical theater program to run our wireless channels. This ensure's we'll have sufficient channels for the orchestra and non theater needs without reconfiguring the board all the time.

I am using the QU-16 as a submixer sending L/R and 4 mixes (one for each monitor in the GL2800). Is there a better strategy for doing this?
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In an ideal world you would have processing that has open channels and go directly in. That is the way we tie in road desks to our PA. But, I doubt you have that capability. I'd probably go in the insert returns of channels, not the pre-amps with your second mixer. Then at least you are bypassing the pre-amp of the channel.
 
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jkowtko

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You might also consider flipping the boards, i.e have the GL as a sub routing into the Qu16 ... I imagine the QU16 might have cleaner sound, plus you can do multitrack recordings of the entire performance.
 

LesWilson

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South Florida, USA
I'd probably go in the insert returns of channels, not the pre-amps with your second mixer. Then at least you are bypassing the pre-amp of the channel.
I was wondering about being able to bypass the GL pre-amps. Thanks. Will have to make some cables.


You might also consider flipping the boards, i.e have the GL as a sub routing into the Qu16 ... I imagine the QU16 might have cleaner sound, plus you can do multitrack recordings of the entire performance.
Yeah, thought about that but I want other people (noobs) to be able to use the existing system without turning on my QU-16. Thanks.
 

TimMc

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I was wondering about being able to bypass the GL pre-amps. Thanks. Will have to make some cables.


Yeah, thought about that but I want other people (noobs) to be able to use the existing system without turning on my QU-16. Thanks.
I'd not use the insert jacks, use the 1/4" line input jacks.

Based on the pic of the QU, you have some gain staging issues. It's not normal to see faders up at full travel.

BTW the issues with your GL2800 are likely ribbon cables and dirty switches. While time consuming to fix, these are not fatal problems. Clever stand you built for the QU, too!
 

LesWilson

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South Florida, USA
Ahh that stand was quite tricky. Thanks. Ignore the QU faders. I had just wrestled the unit into position after pulling it out of its case. When the GL channels are at unity gain, the QU master is at -20. THere's plenty of signal to go around. I'm making some cables tomorrow and will follow up.

The most common behavior with bad channels is intermittant loss of signal during usage. Not completly though ... signal just gets weak and thin. Muting the channel and racing the gain and faders to and fro clears it temporarily. After it happens regularily, I throw in the towel. A couple channels are dead. I'm not adverse to bringing it back to life. Our TD wants to replace it with a Soundcraft analog 48 channel (I'm not enthusiastic about that). Can you describe exactly what you recommend to do to the GL? Are there service manuals available?
 
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FMEng

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This happens with every older, analog console. Switch contacts that don't get exercised regularly get oxidized by pollutants and humidity, and flake out. The insert jacks have switch contacts to close the audio path when nothing is plugged in. Buy a couple spray cans of DeoxIT D5. Spritz it into every channel and buss insert jack, then plug/unplug a connector into the jack several times to exercise the contacts. Unplug each ribbon cable and spray the male and female pins, and then mate them. The buss assignment switches may need to be flooded with D5 and exercised, too.

I take care of an older Soundcraft analog console. It needs this maintenance about every 2 years. I had a Mackie Onyx do the same thing. These days, buying a large, analog console is foolish. The Mackie was given away, and the Soundcraft is slated to be replaced before the next cleaning is due.
 

LesWilson

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South Florida, USA
Thanks @FMEng, I can do the D5 treatment of the jacks easy enough. Can I do the buss assignment switches externally or must that be done from the inside? I'll have to wait till summer to open it up.

We really only need the full 48 when we use all 16 wireless channels for 2 months out of the year. If the GL is replaced by a QU-32, does it lash up with the QU-16 the same way via a set of input channels for the submixer or is there a better setup for an installation with multiple mixers? TIA
 

TimMc

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Multiple mixers are a kludge. The problem for musicals is that you can't easily sync the automation (sure, Qlab and SCS and other cue-firing software can do it, but if you're not using those now.....) and that you burn inputs on the larger console to get left, right, subs, front fills, balcony fills, cry room/lobby/dressing room feeds into it. Of course those all depend on how you're routing signals and what sub-systems you have to drive.

{there went 20 minutes of typing... I should have looked at the QU web pages first)

My suggestion, after looking at the QU ecosystem and the SQ models... is that the QU 16 is limited to 24 input to mix, even if you add a compatible digital snake box and if you're replacing the 2800 anyway, move up to the SQ. All the SQ models are 48 inputs to mix; the primary difference between the 5/6/7 is the number of faders and other physical controls on the surface and the number of XLR inputs on the back. Digital snake boxes can increase the number of inputs if you buy an SQ5, for example, and the box can be at FOH or on stage and connected with CAT5 cable.

Picking consoles is both fun and frustration. Just don't let them install analog. Not that's it evil... but that it represents backing the dying horse.
 

LesWilson

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South Florida, USA
Thanks @TimMc . The QU-16 was a personal purchase to improve my quality of life both in terms of hair loss/headaches and a way to have the functionality in spite of what the GL is replaced with. It's also a way to teach my students digital. We have 16 wireless channels and that's not changing anytime soon. I just burn 6 channels for the QU (L/R and 4 monitor mixes) out of the 16 I'm freeing up. It does make a future 32 board a 26 though. But again, it's just for "play season". Everything else stays put on the GL.

Good points about the future possibilities and issues with automation. Have to think about that. We don't do any from audio right now. A QU-32 is half the cost of the Soundcraft analog but replacing Avioms with ME adds to the total cost. I'll look at the SQ vs budget.
 

TimMc

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Switches need to be done from the inside. Try the inserts first.
Ditto! And the reason is the Rean brand (the cheap division of Neutrik) switching jacks are notorious for eventual intermittent switching operation due to corrosion. DeOXIT is your friend, along with a vigorous "excercising" with a 1/4" plug, inserted and withdrawn multiple times.
 

LesWilson

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Mar 2, 2012
Location
South Florida, USA
Switches need to be done from the inside. Try the inserts first.
I found a Youtube video of a guy overhauling a GL4400. So I see the ribbon cable. These are the boards from it. The switches look like they are fully enclosed. Not sure where to clean them. Thoughts?
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RonHebbard

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Waterdown, ON, CA
I'm not familiar with that particular switch. All you can do is look for some opening to flush cleaner into. Perhaps around the shaft. Failing that, liberally exercising the switch can polish the contacts.
@LesWilson and @FMEng Back when I still had a life, I used to have occasional problems with the Pattern Selector, Pad, and High Pass switches on all four of my AKG 414's (The original 1976 version before they began producing any of the several "Improved" / "Value Engineered" [Cheaper] models.)

I owned four; the first pair were used the most, the second pair were only used when I needed more than 2. This resulted in #3 and #4 seeing appreciably less use. Whenever I wanted to use either of #3 or 4, I'd carefully exercise all three of each mic's switches and they all performed flawlessly for another session; a "session" could be as little as ten minutes or as long as two weeks, simply exercising all 3 of each mic's switches kept the 414's performing WITHOUT having to lubricate, re-lubricate & clean all excess cleaner from their housings only to require repetition the next day.
Toodleoo!
Ron Hebbard
 

Ben Stiegler

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Sf Bay Area
Hate to suggest it, but if you can get a line on someone dumping the same analog console and organ-harvest some modules for backup ...

a school I teach at was terrified of going digital in the theater 8 years ago. I had to promise that we would teach on a smaller analog mixer first. That lasted about 4 months ... the kids instinctively "got" the digital platform and pretty soon I was telling them "I'm sure you can figure that out" instead of rolling up my (mental) sleeves. I learned some neat tricks from a few of them.
Somehow maybe you can decouple the guy with the budget control and analog preference from his having to be able to run it...
 
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DrewE

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Mar 18, 2019
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Vermont
Full Compass lists replacement parts for man Allen and Heath mixers, including the GL2800. They don't list them as in stock so one would have to call about availability. Prices didn't look too out of line to me. My impression, without any actual data or direct experience to back it up, is that in general Allen and Heath is better than average at making available repair parts and service info.

If it's the faders themselves that need replacement, they probably are available from various electronics suppliers such as Digi-key and oughtn't be super expensive. They do wear out with use, like any mechanical device; often a good cleaning/lubrication is all that's required to get them in good shape again.
 

JackyB

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Oct 17, 2019
Location
Newbury Park, CA
I'd not use the insert jacks, use the 1/4" line input jacks.

BTW the issues with your GL2800 are likely ribbon cables and dirty switches. While time consuming to fix, these are not fatal problems. Clever stand you built for the QU, too!
This was the problem with our GL2400 a year or so back. Our district tech replaced some ribbon cables (I think that's what he said) and a few of the dead channels jumped back to life on us.