Advice needed. Problem with PA/Desk at last Saturday nights gig.

kennedydream1980

After some advice folks.

So at this last weekends gig on Saturday night we had a problem with our gear, which I think was down to a dodgy power source, Venue was a marquee on a village green, power source provided was one 2 way extension running from a village hall next door.

The gear being used was a Presonus Studiolive 16.4.2 desk, 2 KV2 EX12 tops and to KV2 EX2.2 bass bins. 2 Guitar amps and a bass amp were also running, as well as a laptop, and various rack gear (Singers wireless Mic, Wireless In ear monitors)

We set everything up as normal, went to start the background music from the laptop and the output level on the desk was really low. Checked all the channels on the desk and it was the same for all, we were using the right side out of the stereo output on the desk to the speakers, I switched it to the left output and also to the mono output it was still the same. Also tried a Microphone in all inputs with the same results, really low output.

If you increased the gain on the channel to compensate for the volume drop the volume would increase slightly but it was distorting quite badly. 

The lead guitarist in the band was also having problems with his amp (Marshall JVM), the distortion channel was very weak and fuzzy.

My question is could this be down to a dodgy mains power source or do you think our desk has developed a fault?. We ended up having to use the singers little 4 channel Yamaha analogue desk which worked fine and got us through the gig.

Would a dodgy mains power source effect a digital desk more so than an analogue desk? It's the first time something like this has ever happened so I'm just after some possible causes.

Cabicular

You didn't accidentally press the 4db button at the back ? Don't know if the presonus mixer has the same line level switch but if I had a penny for every time it happened with the Mackie ...

Cabicular

In the presonus it is a tiny pot by the output jack which lets you vary the output Someone maybe turned it by accident ?

kennedydream1980

No it doesn't have that, it has level knobs round the back for the stereo out and mono output but these were both full up.

Cabicular

the trim pot would be my first port of call Bearing in mind Marque gigs need double the pa of a normal gig and sound weird due to the lack of solid surfaces ... So the sound beams away However if it was alright with the Yamaha desk then barring the trim pots I don't know what else it could be It's unlikely power would cause those symptoms it either would work or drop out

kennedydream1980

Mmm that's what I feared, I think there may be a problem with the desk :-(

Danny1969

We had a similar problem with our Studiolive 16:4:2. After soundcheck we lost all control of the faders, pulling down or pushing up the faders did nothing, there was just the same low level going through and not even controlling externally via the laptop connected to the firewire or ipad could change anything level wise

I fixed ours myself. It's been a few years but basically it uses ordinary faders as voltage dividers rather than digital encoders and it assigns a digital level from that. Because ours had a couple of worn faders it couldn't read the level and the software basically was hanging. I stripped it down, changed a couple of the faders, did a couple of other things like glue'ing some caps to the board (vibration had also broken a cap leg) and checked the SMPU joints and caps and it's been fine ever since 

Here's the basic sections showing the faders in groups, pretty easy desk to work on

And the motherboard 

And here's the smps unit

http://www.thesuperheroesonline.co.uk/sl5.jpg

If your only using the desk in standalone mode, not using using it firewired up to a laptop and running universal control and it plays up level wise then I would suspect your desk had a similar fault to mine. Now you may get away with cleaning the faders, that is something you can do fairly easily 

ICBM

Set up the whole rig somewhere you know the power is good and test it before assuming there's a problem with any of the gear.

It *could* be just a coincidence that the JVM wasn't working right as well, or it could be because of a bad power supply.

Take the 2-way extension cable (if it was yours) and compare the rig with everything going through that vs plugged in normally.

maltingsaudio

Interesting the Yamaha desk worked yet the Prosonus didn't, First port of call in this is always check the cables, if you used the same one to check left right and mono do you know this one was good?

I agree with ICBM's thinking, 

Did a festival on saturday and the genie went down seems like the day for it! We ran sound from the rugby club whilst the lampies sorted the genie out, funny crowd didn't complain about lack of lights bet they would if it was the other way round!

Danny1969

I hope it's a cable issue but if you swopped desks and suddenly the same PA and cables worked fine then it doesn't sound like anything other than the desk

I still suspect the desk simply because that's what the Studiolive does when it goes faulty. The only control your left with is the gain because that's the only analog control on the desk .... trouble is too much gain there and you clip the input of the analog to digital convertor as you heard. Ours lost control of  every fader including Aux A and Aux B stereo in

If you haven't already make sure you have flashed the desk to the latest firmware and then load a zero'ed out patch and see what you have. You can check using the headphone out as all the problem will be before the digital to analog conversion 

kennedydream1980

Cheers guys for all the help, I'm gonna get the gear setup in my local working men's club, and see if I can locate the problem using the suggestions put forward.

BigMonka

Could the issue be due to voltage drop on using long extension leads? I'm not sure how a desk would behave with too low a voltage, or whether they've now all got SMPS units that'll take pretty much any voltage?

kennedydream1980

That could be it, the extension reel running from the mains in the village hall must have been about 30-40 feet long. Could that have caused the problem?

Danny1969

The Studiolive use's an SMP unit which uses pulse width modulation to keep the output voltage constant despite the load, it does this my comparing the output voltage to a known reference voltage and vary's the width of the pulse to compensate. It can be affected by off \ on \off \ on mains type faults but is very unlikely to be affected by a small drop in mains voltage 

You may well find the next time you turn it on all is well. That is the nature of digital desk faults, sometimes for no reason my QU loses audio in channel 7. Give it a reboot and it's back. The digital Tascam DM we were using used to have a funny 5 mins every 20 or so gigs. These things do become known and are generally fixed in firmware updates .... which is why I said make sure your on the latest firmware ...... If you need to flash it download and use the Universal control software from Presonus's site 

Unfortunately our own Studiolive lost the plot until nothing could be done except strip it down and repair it. Even now though we still carry an 8 channel Soundcraft Spirit just in case. 

Let me know how you get on and I hope it is something simple but if it's not there's still options for fixing 

kennedydream1980

The singer in the band has checked it and says it's working fine now. I'm going to update the firmware regardless, just to be on the safe side.

I think we may pickup another desk as backup though, possibly the smaller presonus board.

ICBM

kennedydream1980 said:

That could be it, the extension reel running from the mains in the village hall must have been about 30-40 feet long. Could that have caused the problem?

At only 30-40', not because of the length itself. But -

What gauge cable was it? Many extension cables are only 6A-type cable (0.75mm²) when they should be 16A (1.5mm²). The thinner the cable, the higher the resistance. Although unless the current draw of your equipment was well over 1KW continuous average (not that likely unless you were running lights too) it still shouldn't make much difference.

Were the connections at both ends really secure - wire stripped properly and preferably folded back on itself, screws really tight? Were the plug pins and the socket contacts clean? This can be important. A poor connection can introduce enough resistance to cause trouble.

When you say 'reel', was it unwound fully or was a large amount of it left on the drum?

Was the electricity supply in the building OK?

I know you probably won't know the answer to at least one of these questions, or more if the cable wasn't yours - but it could be the cause, and if the gear seems to work fine now there's a better than evens chance I think. The fact that two completely unrelated pieces of equipment were playing up at the same time makes me think so.

kennedydream1980

@ICBM

The extension reel in the marquee was provided for us, the bass player in the band just reminded me also that they ended up plugging that extension reel into the pub on the other side of the marquee, just to rule out the village hall power being the problem. (I'd forgot all about this as it was a bit manic at the time) The problem was still there with the power coming from the pub.

So I would guess it could be down to their extension reel.

We have another gig this Saturday in a similar kind of scenario, however by the sounds of it the Marquee is in a remote location so I guess the power will be running of a generator.

Is there anything we could buy which would regulate the power to avoid this happening again. Would a Power conditioner do the job?

 

ICBM

kennedydream1980 said:

@ICBM

The extension reel in the marquee was provided for us, the bass player in the band just reminded me also that they ended up plugging that extension reel into the pub on the other side of the marquee, just to rule out the village hall power being the problem. (I'd forgot all about this as it was a bit manic at the time) The problem was still there with the power coming from the pub.

So I would guess it could be down to their extension reel.

We have another gig this Saturday in a similar king of scenario, however by the sounds of it the Marquee is in a remote location so I guess the power will be running of a generator.

Is there anything we could buy which would regulate the power to avoid this happening again. Would a Power conditioner do the job?

Maybe. I would be concerned about running a digital desk from a generator anyway though, even with a power conditioner unless it was something really effective - hence large and expensive. Power fluctuations can cause all sorts of trouble…

Old analogue solid-state gear is your best bet for situations like this.

For the places where you can use mains power, what you need is you own really decent, full-thickness extension cable which a proper electrician has made or checked (if you don't do this sort of stuff yourself) and which you never leave partially coiled up on a reel.

kennedydream1980

I've suggested to the guys in the band it might be a good idea to buy an analogue backup desk. Only problem is we would need at least 4 aux sends, we play with a click track so the drummer needs his own mix, plus 3 of us use in ear monitors. Any suggestions @ICBM

ICBM

I'm not really up on desk specs but big old analogue desks with that sort of feature set should be fairly cheap now, even if they're annoyingly big and heavy.

Is there any way you can simplify the set-up for this sort of gig?

kennedydream1980

That's exactly what we had to do at the last gig (simplify), as we only had the singers little Yamaha 4 channel analogue desk, we ditched the click track and played as a straight up 5 piece band, backline amps providing the sound, only the  kick drum mic'd up on the kit. The singer went in a bit of a sulk as he is very pro click track, but my attitude was just make sure the show goes on however that may be.

So the backup desk would have to have at least 12 XLR inputs and 4 aux sends to accommodate the click and the individual monitor mixes, the only thing I can see that would fit the bill would be an Allen & Heath Mix Wizard.