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[Amin Tobin]

I was working a 4 day music festival this past week running...

2x - EAW AS690i Dual 12" Main Full Range Speakers
4x - Martin W8CS 15" Subs
2x - QSC PLD 4.5
1x - DBX DriveRack PA2
1x - Furman PL PLus II Power Conditioner

3-4 times each day, with no obvious rhyme or reason, the QSC amps would set themselves to standby mode. The amps themselves were running extremely modestly. No peaks whatsoever. Pushing the power button would remove them from standby mode and get things going again. They'd go for 3-4 hours and do it again. I don't understand what could be triggering this. Anyone have any experience?

On a side-note, the sound with this setup with absolutely stunning. I just wish I could walk away from it without having to worry about the standby triggering. 

[Steve-White]

Could be a power quality issue.  Is it on utility or generator?

[Tim Weaver]

The PLD amps don't have the best reliability record. Even ones that sit in a clean install tend to fail pretty early, failing to boot. YMMV, but most of us have moved on. QSC is still a great manufacturer, but everybody lays a turd every now and then.

[Steve-White]

I'll give ya the two turds in a punch bowl.  But, failing in a synchronized manner is unusual.

[Bob Faulkner]

We use 4 x of the PLD 4.2 (mostly for monitors).  Have never experienced any issues. 

Sounds like an issue with power (as referenced before).  What is the firmware level of the amps?

[Kevin Maxwell]

I never use a power conditioner on Power amps. I would remove the amps from that and see if you still have problems. 

[Steve Eudaly]

I never use a power conditioner on Power amps. I would remove the amps from that and see if you still have problems.

I don't see that being the issue. It's pretty much just a rack mount power strip with a voltage meter.

I like where Steve White was going with this. Where is your power coming from? Did you happen to check it under load with a proper meter?

Electronics dropping in to stand-by on their own does seem like a potential side effect of voltage dropping below a certain threshold.

Were the two amps doing this at the same time?

[Steve-White]

I was working a 4 day music festival this past week running...

2x - EAW AS690i Dual 12" Main Full Range Speakers
4x - Martin W8CS 15" Subs
2x - QSC PLD 4.5
1x - DBX DriveRack PA2
1x - Furman PL PLus II Power Conditioner

3-4 times each day, with no obvious rhyme or reason, the QSC amps would set themselves to standby mode. The amps themselves were running extremely modestly. No peaks whatsoever. Pushing the power button would remove them from standby mode and get things going again. They'd go for 3-4 hours and do it again. I don't understand what could be triggering this. Anyone have any experience?

On a side-note, the sound with this setup with absolutely stunning. I just wish I could walk away from it without having to worry about the standby triggering.

"Power conditioners" in that price class are useless in that sense.  They are however useful as plug strips in a rack.  As has been noted, they are not to be used for high current draw items like power amps.  If you have a single AC feed to the Furman and both amps are connected to it, without further analysis that's a 95% probability of the issue.  Depending upon power source, length of run for the AC feed and gauge of wire, and condition of all connections.

What say ye for the electrical feeds and power source?

[Steve Eudaly]

If you have a single AC feed to the Furman and both amps are connected to it, without further analysis that's a 95% probability of the issue.  Depending upon power source, length of run for the AC feed and gauge of wire, and condition of all connections.

But I don't think the Furman in and of itself caused the issue. If the current draw was too high for it, the Furman's circuit breaker would've tripped.

I do agree that the power source upstream or the "feeder" cabling being used could be the culprit.

[Steve-White]

But I don't think the Furman in and of itself caused the issue. If the current draw was too high for it, the Furman's circuit breaker would've tripped.

I do agree that the power source upstream or the "feeder" cabling being used could be the culprit.

I don't write well.  Not suggesting it was the Furman itself.  A single power feed to the Furman is what I suspect.  The Furman itself "could" be an issue if something inside were defective, and that would be about 1% probability.  The gaps in my comments cause Firestorms at times.  Not my intent brother.

I am thinking the issue to be a single feed AC line to the amp rack - or, power quality at the source.

There's a problem, both amps are exhibiting the same symptoms.  99.375% probably it's not the amps, but a common denominator being power.  Another problem could be HEAT.  Are they in an un-ventilated rack sitting in the sun?  90 degree plus day?

For a setup like that, I would be using 2x 12 Ga feeds for AC up to 50', then 10 Ga.  Those are pretty big amps.

[Brian Jojade]

If both amps are failing at the same time, chances are, you're dealing with something impacting both amps.

Possible common causes are AC power, input signal, or USB signal.

AC power is probably the most likely.  While a full power outage will cause the amp to reset and it SHOULD come back on in the same state that it was in, partial shutdowns, or sudden voltage swings could cause the CPU to get confused and do weird things.

An input signal that has an issue, such as DC bias on the signal might cause a problem, although I've never seen that with this amp.

If you have the devices connected with USB, you could be remotely triggering a shutdown.  If you don't have them connected to a computer, go ahead and do that. Then you have detailed monitoring that could help determine what the problem is.

The power conditioner you are using is only a fancy surge suppressor. It will clamp down voltage if it goes above 140v. It doesn't 'condition' in any way other than that.  It's only rated for 15 amps, so if you pushed the 4.5's hard, you'll be well above that.  Still, you'd simply trip the breaker. The conditioner itself shouldn't be a cause to this problem, unless for some reason the circuitry inside is creating some weird harmonics messing with the amp. (very unlikely)

If heat were the issue causing this, it seems extremely unlikely that both would fail at the exact same time.

[Amin Tobin]

First off, thank you all for taking the time to reply.

The power was coming from the grid at the festival/venue but there were others on the same source so we were impacted by them, I'm sure.

I don't know much about the Furman but we did have an artist crank the output by mistake and tripped the Furman fuse. For that reason alone, I'm keeping it in the chain. Although another solution may be to remove it out of the chain and just set the limiters on the amps to something a little more conservative.

The amps weren't returning back to their original state after cutting the signal. They definitely always turned back on in standby mode. To be fair, I don't even know if they really turned off or just went into standby mode.

Thanks for the tip, Brian Jojade, about keeping a computer connected. I'll do that from now on and keep things monitored. I would be awesome if the amp itself kept some type of log that I could download after though. What screens do you think would be helpful to monitor?

I did consider that heat could be an issue since the rack was in direct sun at some points in the day but I came to the same conclusion that they both wouldn't turn off exactly at the same time.

It was the first time I was able to run the system as loud as we did so that why there were so many new variables but I'm feeling like the theme here is the AC power at the venue. I had a feeling but I appreciate the support!

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