Weird problem during gig - Any ideas

[Linus27]

Did a small festival gig today and had a strange moment with my amp. It's a Genz Benz Shuttle 6 running through two Aguilar GS112's. Never had a problem with it before and used it in rehearsals a week and a half ago with no problem. There was a sound engineer there who just mic'ed up the bass so no DI involved. I set up, quick line check and all sounded fine. I used the power cable on the side of the stage to plug into for power. So, started first song and the bass was cutting in and out as if it was clipping. I was probably between 1/2 and 3/4 volume, maybe not quite that so still plenty of room. The harder I played, the more it cut out. I eventually had to go direct through the PA which was not ideal. When I got home, I tried my set up again and not a problem. I whacked the volume up really loud and still no problem. I turned it up so loud that all the red overdrive lights were flashing yet it still did not cut out.

So, anyone go any ideas what this could had been at the gig? Dodgy electrics from the people providing the PA/sound engineer. Like I say, no DI, just mic in front of the speaker and the power coming from the extention socket that was already on stage.

Any thought really appreciated.

[Musicman20]

That screams power supply problem...sounds like it was fluctuating. I doubt it's your setup

Is this a new band you've joined?

[Guest johnzgerman]

sounds like the amp was not getting a constant voltage or current, were they running the stage power off a generator by any chance?

[Linus27]

[quote name='Musicman20' post='878531' date='Jun 27 2010, 12:20 AM']That screams power supply problem...sounds like it was fluctuating. I doubt it's your setup

Is this a new band you've joined?[/quote]

Cool, thank you. I also heard that the keyboards were doing some strange things.

Not a new band as such. It's a U2 tribute band that I dep for when the bass player can't make it. I kind of got recommended as I know all the U2 stuff. Not really my cup of tea playing covers as I find it really hard to draw any emotion from and a bit like painting by numbers. Not a negative comment towards those who do covers but my 23 years of bass playing has always been originals so it feels a little weird playing covers However, a great bunch of musicians and they always go down really well. Encores every time and always people up dancing so still good fun and bonus that you get paid for it Guitarist is also going to play for my originals project.

[Linus27]

[quote name='johnzgerman' post='878535' date='Jun 27 2010, 12:26 AM']sounds like the amp was not getting a constant voltage or current, were they running the stage power off a generator by any chance?[/quote]

Yes, a little generator behind the stage. Is there anything I can do to avoid this happening in the future?

Edited June 26, 2010 by Linus27

[Guest johnzgerman]

[quote name='Linus27' post='878548' date='Jun 27 2010, 12:41 AM']Yes, a little generator behind the stage. Is there anything I can do to avoid this happening in the future?[/quote]

yes, get a UPS (un-interuptable power supply), but thats probably out of must peoples price range and quite unnecessary most of the time. So take a multimeter with you to gigs and check the power before you plug stuff in, that way you will at least know that it is the venue that is at fualt and you will have to use a DI rather than rely on your amp for noise, not ideal but it won't cost you much.

[Jean-Luc Pickguard]

Apart from cutting out and ruining the gig, does anyone have any experiences (or secondhand anecdotes even) where this kind of scenario has killed the equipment - or is it likely to be safe? It sounds like it could have got expensive it had blown up Linus27's rig.

Edited June 27, 2010 by Jean-Luc Pickguard

[Musicman20]

[quote name='Linus27' post='878547' date='Jun 27 2010, 12:40 AM']Cool, thank you. I also heard that the keyboards were doing some strange things.

Not a new band as such. It's a U2 tribute band that I dep for when the bass player can't make it. I kind of got recommended as I know all the U2 stuff. Not really my cup of tea playing covers as I find it really hard to draw any emotion from and a bit like painting by numbers. Not a negative comment towards those who do covers but my 23 years of bass playing has always been originals so it feels a little weird playing covers However, a great bunch of musicians and they always go down really well. Encores every time and always people up dancing so still good fun and bonus that you get paid for it Guitarist is also going to play for my originals project.[/quote]

Sounds great!

[Linus27]

[quote name='johnzgerman' post='878553' date='Jun 27 2010, 12:54 AM']yes, get a UPS (un-interuptable power supply), but thats probably out of must peoples price range and quite unnecessary most of the time. So take a multimeter with you to gigs and check the power before you plug stuff in, that way you will at least know that it is the venue that is at fualt and you will have to use a DI rather than rely on your amp for noise, not ideal but it won't cost you much.[/quote]

Ok, thanks for your help.

[Guest johnzgerman]

[quote name='Jean-Luc Pickguard' post='878556' date='Jun 27 2010, 01:02 AM']Apart from cutting out and ruining the gig, does anyone have any experiences (or secondhand anecdotes even) where this kind of scenario has killed the equipment - or is it likely to be safe? It sounds like it could have got expensive it had blown up Linus27's rig.[/quote]

generators dont tend to do large spikes in power etc but they drop severly if they have too much electrical load put on them like a lighting rig, hence there are normally at least 2 generators at most reasonable size outdoor stages-one for PA/backline and one for the lights.

[Linus27]

[quote name='johnzgerman' post='878561' date='Jun 27 2010, 01:16 AM']generators dont tend to do large spikes in power etc but they drop severly if they have too much electrical load put on them like a lighting rig, hence there are normally at least 2 generators at most reasonable size outdoor stages-one for PA/backline and one for the lights.[/quote]

Any reason why my rig was the first to suffer? Saying that, we did hear that the keyboards were having problems also at the start. Probably cleared up after I was taken out of the loop.

[LawrenceH]

[quote name='Linus27' post='878565' date='Jun 27 2010, 01:34 AM']Any reason why my rig was the first to suffer? Saying that, we did hear that the keyboards were having problems also at the start. Probably cleared up after I was taken out of the loop.[/quote]

Probably your rig was drawing the most power at those moments when you dug in. Plus with amps like the shuttle with Class D operation and a switch mode power supply I bet they're more prone to dofunny things when presented with fluctuating voltage than older, simper amps.

[Phil Starr]

I love Basschat the answers are always so sensible. It looks like the BBC's description of bassists as the responsible organised ones in the band was pretty close.

The other possibility is that the protection circuits in your amp were cutting in. Some amps have a circuit in the power supply that cuts the power in adverse conditions to protect the amp. Again it would be the generators at fault. It does mean that your amp won't suffer any long term harm though.

[thepurpleblob]

The point here is probably "little" generator out the back. Generators are a complete nightmare. If you really want to be worried, go and read about earthing and generators - you may not even have been completely safe. Amps and stuff don't take that much power but it adds up. We've all run the whole band off a single 13A plug but that can supply 13x240 = 3,120 Watts. A typical 2.5KVA generator will only supply about 2,200 Watts - a good bit less than a single socket can supply. And, they are rarely specced to run at full power continuously. If you overload it, the voltage is going to drop and beyond a certain point your amp is going to get unhappy.

EDIT:
For critical applications, generators are available with voltage regulation. I suspect they didn't have one of those.

Edited June 27, 2010 by thepurpleblob

[gary mac]

The same happened to me with my shuttle six, when playing a festival last year. It's the only time I've had a problem when using this amp, so I put it down to the generator.

[xgsjx]

Mr Blob makes a very good point, a small generator putting out @ 2-3 kva isn't the best thing to be running everything off of. Ideally you'd be wanting a 10+ kva silent runner (not cheap to buy, so best to hire).

[quote name='LawrenceH' post='878571' date='Jun 27 2010, 01:53 AM']amps like the shuttle with Class D operation and a switch mode power supply[/quote]

This. If you was using a valve amp your sound probably wouldn't have cut out but just changed in tone. I doubt it would be good for the amp still.

[bass24]

You could get one of these energy monitors from Maplin

[url="http://www.maplin.co.uk/Module.aspx?ModuleNo=38343"]http://www.maplin.co.uk/Module.aspx?ModuleNo=38343[/url]

This will give you the voltage that the supply/generator is giving, should be around the 230v / 240v if its down to say 200v (this would be a bad case) then you will get the probs that you had at the gig.

[Linus27]

Thanks everyone for the really helpful replies. Seems like you have all hit it on the head with finding the fault. Really pleased it was not my amp playing up.

[Toddy]

Sure its not the heat ???,,, had exactly the same problem yesterday,,,line check only,,,all ok....occasional buzz in couple of songs,, then,,,,, silence...

Everything else plugged into the extension was fine,,,,,, ripped out the DI out the amp,,, went straight DI through the floor pedal,,, engineer turned up the bass in the monitor,,,,,,, survived the gig,,,,,,feck it was hot in there,,,, and the 5 hours in the van didnt help...its now working A1 again,,, which worries the hell out of me..........top of the head suggestion was thermal cut out ???,, never had problem with this amp before,,, and its done a lot of work.....dunno......fingers crossed really,,, cos if lose faith in a piece of road gear,,it will end up in the garage !!

[allighatt0r]

[quote name='Jean-Luc Pickguard' post='878556' date='Jun 27 2010, 01:02 AM']Apart from cutting out and ruining the gig, does anyone have any experiences (or secondhand anecdotes even) where this kind of scenario has killed the equipment - or is it likely to be safe? It sounds like it could have got expensive it had blown up Linus27's rig.[/quote]

I've heard of Multi effects pedals and keyboards being wiped of stored settings by this sort of thing, which, of course, is a major issue for people that rely on stored patches.

[dave_bass5]

I had a similar thing happen to me at a rehearsal studio a couple of years ago. Every time i dug in my MB head would shut down. This turned out to be a faulty cab. After 4 or 5 times i plugged in to another cab and all was fine.
I tried the faulty cab again at a much lower level and that to was ok.

Just saying. Might be worth checking both cabs.

[Linus27]

[quote name='dave_bass5' post='879595' date='Jun 28 2010, 09:50 AM']I had a similar thing happen to me at a rehearsal studio a couple of years ago. Every time i dug in my MB head would shut down. This turned out to be a faulty cab. After 4 or 5 times i plugged in to another cab and all was fine.
I tried the faulty cab again at a much lower level and that to was ok.

Just saying. Might be worth checking both cabs.[/quote]

Thanks Dave. I did try my setup when I got home, at much great power and volume than I did at the gig and it was fine, no cutting out. I even ran it pretty much full volume with the overdrive and clipping light flashing away and still no problem.

[dave_bass5]

[quote name='Linus27' post='879638' date='Jun 28 2010, 10:25 AM']Thanks Dave. I did try my setup when I got home, at much great power and volume than I did at the gig and it was fine, no cutting out. I even ran it pretty much full volume with the overdrive and clipping light flashing away and still no problem.[/quote]

Yeah, i read your post, just wasn't sure if you had run both cabs.

Im sure it was the lack of decent power, like the others said. Just thought i'd mention it.

Hopefully a one off.

[Linus27]

[quote name='dave_bass5' post='879651' date='Jun 28 2010, 10:35 AM']Yeah, i read your post, just wasn't sure if you had run both cabs.

Im sure it was the lack of decent power, like the others said. Just thought i'd mention it.

Hopefully a one off.[/quote]

Yeah, I really hope so. Kind of makes you paranoid and worried for the next gig