well that's wierd....

Shane Presley

Shane Presley

Senior
Jan 12, 2011
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Ottawa, Ontario, Canada
www.bssproductions.com
I had a show this past weekend, where I had to pull my soundcraft MH-2 -48 out of the corner of the shop ( nobody puts baby in the corner - lol)... Anyway, I fired up the desk and the pa, and the left side sounded "crusty",over driven and distorted. So I ran the fader up and down a couple times, and it did nothing to alter or change the sound. We were all in a hurry so I asked the BE if she would run in mono and she didn't have a problem, so we went off the right. Now in hind sight I should have taken the eq out of line, but does anyone have any idea what make a master bus sound over driven. I was working on the trouble from the truck - was actually seeing "bad distored signal" at the amp rack (lab G 10Q) at low volume. From the off position I'd get one green light showing signal then as I slowly turned up the volume, orange/red. I would then take the right send from the console, plug it into the signal path and have clean sound.
at first I thought it was a bad amp, then a bad crossover channel, and then finally traced it to the left side of the console send...

BTW I was using both a microphone source on a channel, and then an ipod on a stereo return - same result.
 
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Re: well that's wierd....

Shane Presley said:
soundcraft

Anyway, I fired up the desk and the pa, and the left side sounded "crusty",over driven and distorted. So I ran the fader up and down a couple times, and it did nothing to alter or change the sound.

finally traced it to the left side of the console send...
Click to expand...

Sounds like the bus not getting enough voltage from the power supply.

I had a Soundcraft do something similar with it's preamps. They would clip "early" PFL'ing the channel showed input levels around -6 would sound OK, but trying to get anything more than that ran them into distortion. Preamps couldn't get the voltage to reproduce the signal at a higher amplitude.

Chris
 
Re: well that's wierd....

What Chris said wouldn't shock me. Soundcraft's have a bit of a history of bad power supply's. Have a Soundcraft Spirit at home (Original series, before they fixed the powersupply) and it will have randon LED's light up, and start humming all the time. Our old Venue II's at the shop usually don't leave because of problems like this, and they're heavy as hell. Have another "Venue" at one of the Venues I do occasional work at, and although its a monitor console, left right outs sometimes do the same thing your's is doing. I did find one quick fix to that problem
though, if your console has any matrix outs on it, try paralleling them with the main outs, and running it through them. If it doesn't have a matrix, send everything through a sub-group and run out of the sub group out. Always worked for me. May not always be an ideal fix, but will get you through the show.
 
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Re: well that's wierd....

Nick Latkowski said:
What Chris said wouldn't shock me. Soundcraft's have a bit of a history of bad power supply's. Have a Soundcraft Spirit at home (Original series, before they fixed the powersupply) and it will have randon LED's light up, and start humming all the time. Our old Venue II's at the shop usually don't leave because of problems like this, and they're heavy as hell. Have another "Venue" at one of the Venues I do occasional work at, and although its a monitor console, left right outs sometimes do the same thing your's is doing. I did find one quick fix to that problem
though, if your console has any matrix outs on it, try paralleling them with the main outs, and running it through them. If it doesn't have a matrix, send everything through a sub-group and run out of the sub group out. Always worked for me. May not always be an ideal fix, but will get you through the show.
Click to expand...

Thanks great ideas to start. Just some more detail... Albeit it was a 12 gauge cable, I was running 200ish feet to foh and I was only getting 115v to begin with at the distro, so maybe lack of power might have been the culprit... I'm opening the console up in the shop tomorrow night(I only do this part time) to see if I can replicate the issue (or not). Funny the console always seems to give me grief using the outboard psu as opposed to the on board psu... I would have thought the inverse... Oh well I'll get a chance to run it up tomorrow, thanks for the ideas... Yeah about re routing, had I not been the only guy onsite I might of had more time to get things sorted...(no I wasn't the only guy onsite, just the only one that could trouble shoot)...
 
Re: well that's wierd....

Shane Presley said:
Thanks great ideas to start. Just some more detail... Albeit it was a 12 gauge cable, I was running 200ish feet to foh and I was only getting 115v to begin with at the distro, so maybe lack of power might have been the culprit... I'm opening the console up in the shop tomorrow night(I only do this part time) to see if I can replicate the issue (or not). Funny the console always seems to give me grief using the outboard psu as opposed to the on board psu... I would have thought the inverse... Oh well I'll get a chance to run it up tomorrow, thanks for the ideas... Yeah about re routing, had I not been the only guy onsite I might of had more time to get things sorted...(no I wasn't the only guy onsite, just the only one that could trouble shoot)...
Click to expand...

Only guy on the job that knows what he's doing? We've all been there plenty of times. Haha. I don't remember the last time I had a crew sent out with me that knew anything.

Also, I'm sure you know already, but just in case, even on a time crunch, always check your voltage after any length of cable over 100 ft. Most power supplys will run on anything between 100v and 125v (Though not always well) but any lower, or any higher can damage equipment with costly repairs.

Although, the 12 Gauge cable should've easily carried the voltage providing you weren't running to much amperage through it. Actually, even at 20amps (max 12 guage is rated) you should still be around 102V if you started at 115V.
 
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Re: well that's wierd....

I'm guessing that power had nothing to do with it. The right bus sounded fine, right? Why wouldn't it be affected by this power issue?

Analog consoles get cranky when they aren't used regularly. I'd bet that if you cleaned her up real good and ran the insert jacks, and lubed some faders she would come back to life.

And if anything like this happens in the future, just run on a pair of busses, or a matrix out. No need to give up stereo!
 
Re: well that's wierd....

Tim Weaver said:
Analog consoles get cranky when they aren't used regularly. I'd bet that if you cleaned her up real good and ran the insert jacks, and lubed some faders she would come back to life.
Click to expand...

Insert jacks are a particular problem with Soundcraft consoles - the normalling gets crusty and you start getting problems like this. Usually you can crank up the gain for a couple seconds and "blast through" the oxidation to get a clean signal for a while.
 
Re: well that's wierd....

Well i opened it up, removed everything from the main bus signal path. Started up an iPhone through stereo return 2. And a mic cable from L into a powered speaker. Left sounded weird and weak in comparison the right. So then i tried what you suggested and brought the matrix level up and went out matrix 1 and 2 , left and right.... The issue switched sides... Right was now bad and left was weak(from the matrix send). Im going to try to video the difference but the best i could say is its the difference berween am radio and fm radio. Less to no low end content out of the "bad side". So i suppose I could run left as left and right out of matrix two. But id really like to know why and fix it. Anyway, still no happening. Console was plugged into my shop direct using the rear internal psu on a 10' a/c. So different psu that the rack mount unit so negates power malfunction. Also tried a 58 into a random channel with the same result. 1,2 1,2 in left. Sound big. Hot swap to right xlr out. Weak 1,2 1,2.... Stumped!
 
Re: well that's wierd....

Shane Presley said:
Well i opened it up, removed everything from the main bus signal path. Started up an iPhone through stereo return 2. And a mic cable from L into a powered speaker. Left sounded weird and weak in comparison the right. So then i tried what you suggested and brought the matrix level up and went out matrix 1 and 2 , left and right.... The issue switched sides... Right was now bad and left was weak(from the matrix send). Im going to try to video the difference but the best i could say is its the difference berween am radio and fm radio. Less to no low end content out of the "bad side". So i suppose I could run left as left and right out of matrix two. But id really like to know why and fix it. Anyway, still no happening. Console was plugged into my shop direct using the rear internal psu on a 10' a/c. So different psu that the rack mount unit so negates power malfunction. Also tried a 58 into a random channel with the same result. 1,2 1,2 in left. Sound big. Hot swap to right xlr out. Weak 1,2 1,2.... Stumped!
Click to expand...

just out of curiosity, did you try switching the matrix outs? (Left to 1;right to 2) to (right to 1; left to 2) just to see if the bad side still switched? Could be possible to have a bad main bus, and a bad matrix? Our venue II has an intermittent problem like that. I realize you just want the source of the problem fixed, but that could help to point out the issue better.
 
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