Problem with QSC GX5

[Dmadmadma]

Greetings,
Before anything I would like to state that I have no idea about how electricity works.I am currently building up a rack system for bass and guitar. So far as a power amp I have the aforementioned QSC and a Yamaha PB1. Unfortunately the power amp shuts usually shuts down when I turn it off and even turned off a switch in the fuse box. The amp is plugged into a power strip, which is connected to a wall plug. According to PA/HiFi forums this is a general problem on this power amps, given that the amp draws a lot of current for an instant (a spike maybe?) while switching on, an inrush current problem, which apparently could be solved with a limiter that goes between the wall plug and the power cord.

Does any of you have an idea how to solve this? Would a Furman (or similar) power conditioner solve this? Many thanks beforehand!

Cheers!

 

[Al Kraft]

I'm not sure I fully understand your problem, but don't agree with that PA/HiFi forum's claim that QSC amps have problems like this - at least not in my experience. However, I do agree that whenever anything is turned on there is a change in current flow/demand and some items have a much larger "start-up curent draw/spike" than others - an air conditioning compressor for example.

Hopefully TB member Bob Lee can offer some simple product specific troubleshooting advice to help you see if it is a problem with the amp. Personally, I would plug the amp directly into the same wall outlet you have the power strip on, power it up, and see if you have the same problem with the amp. If not, it may be the power strip and/or the combination power strip and Yamaha component. If the problem still exists, I would try another outlet on a different circuit (i.e. one that is not on the same fuse/circuit breaker in your home). You might have a bad circuit breaker or too much connected load already on that line from something on that circuit elsewhere in your house (like a dehumidifier or a refrigerator) and the amp coming on line is just the straw that breaks the camel's back.

In any event, troublehooting involves simple steps and isolating individual components so you can discover exactly what the root cause of the problem is. Folks like Bob can be more help, but I think the steps above would be a safe way to start.

 

[Mingo Sanders]

Unfortunately the power amp shuts usually shuts down when I turn it off and even turned off a switch in the fuse box.

It's difficult to understand the problem you're describing. Did you buy the amp new from an authorized QSC dealer? If you did, contact the dealer for support. Otherwise, contact QSC for out of warranty support in your area. QSC amps work. Don't believe the forums.

 

[Dmadmadma]

Sorry! I didn't proof read it and somehow translated it from german. So here I rephrase:

I am currently building up a rack system for bass and guitar. So far as a power amp I have the aforementioned QSC and a Yamaha PB1 as a preamp (I had used an Ampeg before and the same happened). When I turn on the power amp it usually shuts itself down and switches down a breaker in the breakerbox of the room. The power amp is plugged into a normal power strip, which is connected to a wall plug. According to PA/HiFi forums this is a usual problem of the GX line of power amps (QSC's low budget line, although no one complains about their sound), given that the power amp draws a lot of current for an instant (a spike if you will) while switching on, from the translation an inrush current problem. The forums say this could be solved with a limiter that goes between the wall plug and the power cord.

Do you have any idea how to solve this problem? Would a Furman (or other brand) power conditioner solve this?

Better now? I also messaged Bob Lee on Facebook since one cannot message him here.

 

[agedhorse]

Is this an amp that was converted from 120V to 240V (or 115V to 230V)? There may be additional parts needed for the conversion other than the power transformer (or rewiring of the primary).

Generally this is not a problem with the GX series, I have installed many in pro audio installations with absolutely no issues. Everything I have installed has been 120V.

Beware of what you read on the internet, there are a lot of blanket statements made by "internet experts" that are completely false.

Bob Lee is the guy who can get this answered for you.

 

[Dmadmadma]

Is this an amp that was converted from 120V to 240V (or 115V to 230V)? There may be additional parts needed for the conversion other than the power transformer (or rewiring of the primary).

Generally this is not a problem with the GX series, I have installed many in pro audio installations with absolutely no issues. Everything I have installed has been 120V.

Beware of what you read on the internet, there are a lot of blanket statements made by "internet experts" that are completely false.

Bob Lee is the guy who can get this answered for you.

it doesn't seem like it is one of the transformed ones, right?

I'm usually skeptical of these internet experts, but there I have found at least five people with the same problem. I doesn't mean that this is a problem of the QSC per se, but rather of how I am powering it. Maybe all who have no problem with it are using a power conditioner, which I am not. Would that a power conditioner solve this?

 

[agedhorse]

No, generally a power conditioner won't have any effect on this.

Since I don't have any personal experience with the 240V version of the amp, I don't know what might be happening. Bob will know.

 

[Passinwind]

Bob Lee is the guy who can get this answered for you.

Let's ping him: @Bob Lee (QSC)

 

[Zooberwerx]

it doesn't seem like it is one of the transformed ones, right?

I'm usually skeptical of these internet experts, but there I have found at least five people with the same problem. I doesn't mean that this is a problem of the QSC per se, but rather of how I am powering it. Maybe all who have no problem with it are using a power conditioner, which I am not. Would that a power conditioner solve this?

Doubtful as we haven't identified the culprit. First thing I would do is move the rig to another location in your residence on a separate circuit and re-trial. As mentioned, avoid anything that shares higher-consumption appliances.

Riis

 

[BassmanPaul]

If the amp id blowing a breaker in the distribution panel it should not be turned on again until it is repaired. There is something definately wrong.

 

[S-Bigbottom]

My GX5 has been plugged in with and without racks, powerstrips with other gear on it, in different rooms of houses, on stages, outdoors and even in old buildings where we had to hunt down a grounded outlet.
Never had an issue with powering up.

I wonder if these on HiFi forums are plugging in too much gear into their circuits zone. There is usually not far they can go from their TV listening area so everything gets plugged into the two outlets near it, which are likely on the same circuit. Many think just because it is not all plugged into the Same Outlet it is not overloading.

 

[Al Kraft]

My GX5 has been plugged in with and without racks, powerstrips with other gear on it, in different rooms of houses, on stages, outdoors and even in old buildings where we had to hunt down a grounded outlet.
Never had an issue with powering up.

I wonder if these on HiFi forums are plugging in too much gear into their circuits zone. There is usually not far they can go from their TV listening area so everything gets plugged into the two outlets near it, which are likely on the same circuit. Many think just because it is not all plugged into the Same Outlet it is not overloading.

That was my first thought...a dozen things that run steady-state at or very near circuit capacity all plugged into a single power strip so they have one switch turn on conevenience. In that situation I could easily see start-up current tripping a sensitive breaker and the blame instantly and foolishly goes to the last thing they addded or biggest power user as having some type of problem. Sort of a "post hoc, ergo propter hoc" fallacy.

IME many audiophiles are not nearly as engineering savvy or well groundned in science as their purist approach to sound reproduction would have one believe. No offense intended and I'm certain the same could be said of me in some areas of life.

 

[seamonkey]

What else do you have plugged in on the same breaks circuit?
If you have several things plugged in you overload the circuit the breaker blows. If the loads are dropping the voltage the amp may have built in protection. No power conditioner could help.
Read the manual on the supply voltage range and check the wall socket for this voltage range. Read the manual on the current draw, QSC list many, and check the circuit can supply supply this. Try another isolated circuit with no other loads attach.

 

[Al Kraft]

What else do you have plugged in on the same breaks circuit?
If you have several things plugged in you overload the circuit the breaker blows. If the loads are dropping the voltage the amp may have built in protection. No power conditioner could help.
Read the manual on the supply voltage range and check the wall socket for this voltage range. Read the manual on the current draw, QSC list many, and check the circuit can supply supply this. Try another isolated circuit with no other loads attach.

Good point! I'm sure many amps have both over and under-voltage fault detection and protection features.

 

[Dmadmadma]

so apparently the amp is not the problem, but the power of the room or rather the circuit I'm plugging into, right? My question now would be, what can I do to avoid this to happen every time I plug into a different room?

 

[Al Kraft]

so apparently the amp is not the problem, but the power of the room or rather the circuit I'm plugging into, right? My question now would be, what can I do to avoid this to happen every time I plug into a different room?

First, it's only the problem if you've plugged the amp into a different circuit, turned it on, and everything is fine, but when you come back to that original circuit it fails again. Next step would be to have an electrician check your house wiring to be sure you don't have a more serious issue than the amp not working in that room.

I'll let my EE colleagues have the final word, but in my opinion you cannot come fully prepared to every gig to fix the house power, other than to bring your own power source (e.g. generator or batteries) or a commercial grade power conditioning system that can run off most anything as an input and provide pristine uninterruptable power. There is a reason designers provide operating specifications for power and build in self-protection against operations outside acceptable/safe limits.

 

[TOOL460002]

I've practiced in storage spaces where, if other bands were playing nearby, I would have power down issues, and this is also a QSC amp (PLX1804), and I have a 1U Furman, so, ya, it's probably not your particular setup. This seems like a call an electrician thing.

That said, if you're building a rack, I would get a Furman and a long power cable so you can search the venue and find an outlet not shared by, say, another amp/PA/any high draw gear.

Also, I am far from an expert, but I have dealt with what you describe and it was the outlet (but no breakers went off; just powered down and was fine after that. QSC is good stuff.

 

[agedhorse]

I do not recommend using power amps with "power conditioners". Power amps (such as the GX-5) already have all the necessary protection built in.

I suspect (this is not a 100% diagnosis) that there is a problem with the branch circuit supplying the receptacle. This is something that a qualified electrician can test for.

 

[CryingBass]

Always practice safe power!

 

[byacey]

I do not recommend using power amps with "power conditioners". Power amps (such as the GX-5) already have all the necessary protection built in.

I suspect (this is not a 100% diagnosis) that there is a problem with the branch circuit supplying the receptacle. This is something that a qualified electrician can test for.

Most panel breakers will easily handle the inrush current during the split second that the caps charge. I agree that there is most likely other loads on the same circuit pulling considerable current that is already heating the circuit breaker. I don't know what a typical branch circuit breaker rating is at 220 volt, but I doubt its more than 8 or 10 amps.