P.A. weirdness

[irvined]

Hi,

Here's a problem that I just cannot figure out.

We played a gig at a local pub on Friday. I have the P.A. The main parts being a Soundcraft UI16 stage box/mixer and two Alto TS215 powered speakers.

We plugged everything together and ran some recorded music through to check all was o.k. The foldback system worked fine.

When I brought up the FOH only the right speaker responded. I replaced the XLR cable to the left speaker but no difference. At the stage box I swapped the channels and the music continued only from the right speaker. I then connected the left speaker to a spare AUX out channel, copied the FOH mix to it and there was sound from the left speaker. As we had then run out of sound check time (15 minutes) I had to leave things that way. Not a good gig, sound was very bad.

The following day I set everything up in my workshop and all behaved normally, incidentally I had been running everything an hour a day the week before just to ensure it was going to be all-right.

The only thing I can think of is the power in the pub was in short supply. We were show one socket and told "the bands use that" We managed to run another pair of power cables from a toilet and another one from behind the bar. I had everything FOH running from the toilet power except the left speaker and that ran from the bar power. Could that have caused the problem?

Three weeks until our next gig, getting there really early to do a full check and then long sound check..

Thanks.

Regards,

Doug

[Norris]

We usually run everything from a single socket. That's a guitar amp, bass amp, mixer, powered Mackies, foldback wedge and the LED lights plus controller. We've never had an issue. You'd need a fair bit more kit to draw more than 13 amps. We always use an RCD adapter too.

[irvined]

Thanks,

I wasn't thinking that we had drawn too much current, rather that because this is a very old building the quality of power on each different ring may have caused the Soundcraft to do something strange.

Regards,

Doug

[Phil Starr]

The most likely explanation is the leads, though it could be a socket. If there is a poor joint or an invisible break in the cable itself then just wiggling something can re-make the connection. If you've connected it up at home you'll have done a lot of wiggling and maybe swapped leads around. Intermittent faults are a bugger to find. Always carry some masking tape with you to gigs and you can mark the leads in any channel that fails, then you can investigate when you get home. There's also nothing to lose by squirting some switch cleaner into the sockets. Sensibly you could replace all the leads and eliminate them as suspects.

Good luck

[irvined]

Hi,

Thanks for the reply.

I did replace the XLR cable to the speaker that was giving the problem without any change. It only burst back into life when I plugged it into a spare AUX socket and sent a copy ot the FOH mix to it.

Moving the XLR back to the main FOH XLR and it went dead again. Swapping over the XLRs and the sound continued from the right speaker.

Subsequently I tested the cables using my Behringer cable tester and all looked good.

I hope it's not a dodgy XLR on either the UI16 or the speaker, both just over a year old.

Next gig on the 9th, getting in really early to give the entire system a good check out and then a long sound check setting all levels and making new snapshots on the UI16.

Regards,

Doug

[Phil Starr]

Looks like you tried all the right things. If it's all been working OK through the Aux out then it's unlikely to be the speaker end so you are left with the mixer. Could be a connection problem or I suppose a software glitch. You did switch it off and on again! I don't know the Soundcraft, is it possible there's some way of muting the output?

[moonbass]

Although less common on the Soundcraft devices, I find these sort of problems crop up fairly frequently on the stage box digital mixers. Definitely turn off and on again, but I have had to do a reboot on my Behringer XR18 after a particularly buggy soundcheck. Sounds like software is the likeliest culprit here with the checks you made.

[irvined]

Hi,

It may well have been a software glitch. In the time I have used my UI16 (a year from new) it has always behaved itself.

I would have though, if the UI16 had a problem, when I swapped the main out XLRs round the lack of sound would have moved?

Really want to go through the whole system and set levels from the ground up.

I hope to be upgrading to a UI24 next month so that we can record out of the desk and then mix/fix the recording later.

Regards,

Doug

[Si600]

Are you using them directly from the desk, or does one slave off the other? I used my pair of Wharfedale Titans as stage monitoring for the local AmDram panto I did music and lights for this year. They were both working until the last night when one stopped. I tried new cables, swapping the slave/master over. All sorts.

When I got them home afterwards I set them up in the living room and found a button on the back that swapped between CD/Audio in and the XLR in. Just wondering whether you have a similar setup and the button got pressed when you set up.

[EBS_freak]

Are you running the latest firmware on your mixer? I know that the UI16's software has been plagued with it's fair share of bugs. Most seem to have been fixed now though... so worth giving it a shot.

[irvined]

Hi,

I run everything direct out of the UI16 via XLR cables.

So we go main L/H out of the UI16 to one powered speaker and the R/H out to the other.

For foldback we run from two of the aux outs to each of the main powered wedges and then have an extension speaker from each to give more coverage and boost the power (lower impedance)

On the Altos there are two inputs but (as far as I can see) no switching. There's a ground lift switch and an EQ one. Neither made any difference.

I must admit I should have tried slaving the speaker that stopped responding from the working one. That at least would have given me a bit more to go on.

Sadly we were being told by the pub to stop sound checking as the restaurant was about to open.

Regards,

Doug

[irvined]

Hi,

As far as I was aware the latest firmware was only a beta release?

I did upgrade to the earlier firmware release and that has been working fine.

I've never had any wireless problems but now use an external wireless router just to be sure.

Regards,

Doug

[irvined]

Hi,

Well we did the gig last night. I set the p.a. up early. Set some tunes to play from the USB stick and everything performed as expected!

I have no idea why we had the problem at the last gig.

ANYWAY I have now bought a Soundcraft UI24R which is fantastic. More channels, better preamps and the ability to record and send directly to a DAW.

The gig went really well.

I gave the vocalists's wife a 5 minute intro into to the UI24R and she mixed the gig. o.k. I set the levels and we have two tablets onstage for setting the foldback levels but she did FOH.
Just goes to show how easy the UI24R is to manage. The guitarist has taken the USB stick away to mixdown with Sonar and I'm hoping for good things.

The ability to record onto USB and then do your own soundcheck with the whole band is great. Everyone can get a chance to go "ooh I'm too loud". That was the vocalist and I never thought I'd hear that! :-)

So don't know what happened the other week, I really think it was a power issue but I'm really pleased with the UI24R. Got it hooked up to a 32" flat screen in my workshop via HDMI it is great for me.

Regards,

Doug