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Author Topic: QSC 3602 Reliabilty Issues-Anyone?  (Read 13833 times)

Bob Lee

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #30 on: May 06, 2011, 01:27:34 pm »

like a old linear supply with a 30 lb transformer.

No such thing as a "linear" supply, except for maybe a battery.  ;)
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Bob Lee
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"If it sounds good, it is good." óDuke Ellington

Mike Diack

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #31 on: May 06, 2011, 04:55:02 pm »

Repair techs see 100% failure rates on every model.  Users should not.

Ha ha - but repair techs also do work for distributors, so they also get a good idea of the ratio of failures to total number of units sold (close to 100% in the case of iTechs in the first year...the situation has latterly improved) and they also get to know all the local sound reinforcement companies (so get an idea of how things fare in the field). They also get to know how the manufacturers handle the inevitable infant mortalities (unimpeachable in the case of QSC). ***ALL*** amp manufacturers have some failures - it's how these things are handled that really counts.
M
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Bob Leonard

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #32 on: May 07, 2011, 01:42:02 am »

like a old linear supply with a 30 lb transformer.

No such thing as a "linear" supply, except for maybe a battery.  ;)

I've built linear amplifiers for HF that use 3600 volt power supplies. Does that count?  ;D
 
Good to see you post Bob. Hope my dislike of the 3602 isn't upsetting you. And, as a matter of fact the world should also know that all of my ampliers are QSC and that I have used QSC since the product line was conceived. Failures in the past 16 years? ONE.
« Last Edit: May 07, 2011, 11:17:49 pm by Bob Leonard »
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BOSTON STRONG........
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I did a gig for Otis Elevator once. Like every job, it had it's ups and downs.

Alan Sledzieski

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #33 on: May 07, 2011, 08:05:19 am »

No such thing as a "linear" supply, except for maybe a battery.  ;)

Thanks, I don't know how power supplies work, but I was reffering to the amps with big old transformers.
Just picked up a ca18 yesterday I'm happy.
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Todd Rasmussen

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #34 on: May 07, 2011, 08:39:01 am »

If a repair tech sees an amp, it's broken.  So, 100% of the amps the repair tech sees are broken. 
100% failure rate (in his eyes)  He doesn't see the the ones that are working.

If the company sells 10 times as many of a new amp than the old one and the repair tech sees 5 times as many of that amp,
The tech may think they suck because he's seeing 5 times as many, but reality would be that the new ones are twice as reliable as the old ones.


If one considers the reliability of an amplifier with MTBF of "X" hours, adding just one new part that is less than 100% reliable decreases the MTBF of the amp.

I think the point Alan is making, and I tend to agree, is that newer amps tend to be more complex with the switching designs and the DSP stuff. So, merely by the (likely) addition of more parts and more complexity, the reliability inherently decreases if these additional parts/systems are anything other than 100% reliable. The only way to maintain (or grow) reliability then is to make reliability improvements in other areas to offset the new content's failure rate.

That said, I don't know what the numbers are but I do know that individual reports of failure don't necessarily imply the overall reliability experience of the entire population. MTBF of 10,000 hours doesn't mean every amp will last 10,000 hours, it means only that it is the average of the population. On a population of two, amp A fails after 1 hour use and the other fails after 19,999 hours means MTBF = 10,000 hours. Of course, such a small population is merely for example.
« Last Edit: May 08, 2011, 09:53:28 am by Todd Rasmussen »
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Alan Sledzieski

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #35 on: May 07, 2011, 10:27:27 am »


If one has an amplifier with MTBF of (for example) 10,000 hours, adding just one part that is less than 100% reliable decreases the MTBF of the amp.

I think the point Alan is making, and I tend to agree, is that newer amps tend to be more complex with the switching designs and the DSP stuff. So, merely by the (likely) addition of more parts and more complexity, the reliability inherently decreases if these additional parts/systems are anything other than 100% reliable. The only way to maintain (or grow) reliability then is to make reliability improvements in other areas to offset the new content's failure rate.

That said, I don't know what the numbers are but I do know that individual reports of failure don't necessarily imply the overall reliability experience of the entire population. MTBF of 10,000 hours doesn't mean every amp will last 10,000 hours, it means only that it is the average of the population. On a population of two, amp A fails after 1 hour use and the other fails after 19,999 hours means MTBF = 10,000 hours. Of course, such a small population is merely for example.

The gentleman I bought the ca18 from tried 2 pro 9200's, they both went down in the first year, or second. his friend bought 6 9200's, 3 or 4 of them went down in the first 2 years.  I'm the not so proud owner of 4 8200's, I use 1 bridged on a double 18, I run 4 double 18's.  If I loose 1 double 18 do to a amp going down, no big deal, the show goes on.  If I put a 9200 on my 4733's and it goes down, its a big deal.  That's why I bought the ca 18.
 Whatever the case is, between crest, qsc, and crown, the new light weight amps fail much more often then the old big transformer amps, I can count and do the math, lol.  Problem is, there heavy.  Imagine lifting 5 ca 18's and 2 ca9's into the back of a pickup.  I'm to old for that.
 Wish crest was still crest.
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Chuck Simon

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #36 on: May 07, 2011, 11:44:45 am »

So, did anyone happen to see the title of this thread?  Man, it's hard to get a straight answer around here!
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Bob Leonard

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #37 on: May 07, 2011, 11:21:00 pm »

So, did anyone happen to see the title of this thread?  Man, it's hard to get a straight answer around here!

I read the post, and I think I gave you more than one answer. I have some more if you like.
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BOSTON STRONG........
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I did a gig for Otis Elevator once. Like every job, it had it's ups and downs.

Jeff Bankston

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #38 on: May 08, 2011, 12:16:07 am »

So, did anyone happen to see the title of this thread?  Man, it's hard to get a straight answer around here!
Mongos straight !
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Doug Maye

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Re: QSC 3602 Reliabilty Issues-Anyone?
« Reply #39 on: May 08, 2011, 10:30:55 am »

So, did anyone happen to see the title of this thread?  Man, it's hard to get a straight answer around here!
There are probably better than 20 of them in this area being used on sub duty. To the best of my knowledge none have had problems due to the amp itself. Power in the venues yes, amps no.
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ProSoundWeb Community

Re: QSC 3602 Reliabilty Issues-Anyone?
¬ę Reply #39 on: May 08, 2011, 10:30:55 am ¬Ľ


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