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Title: Power amp life expectancy
Post by: Scott (Abrahamson) on May 30, 2017, 11:45:40 pm
I have three Crown CE4000's that are around fifteen years old and doing 30 to 40 gigs a year that are in excellent condition and still working great.

Would you trust using them for another five years?

 Is there a practical lifespan for power amps?

Scott

Title: Re: Power amp life expectancy
Post by: Jeff Bankston on May 31, 2017, 12:53:40 am
i have about 50 QSC Series 3 amps. Some were made in 1982 and still work fine. I will use them until the quit and cannot be repaired. The B52 bomber is expected to fly another 25 years and I have flown on DC-9 jets that were made in the 60's. I also have a 65 mustang, a 68 torino and just parked my 1995 ford f250 that is going to be making a 4000 mile trip in august. I also have a 1973 fender twin amp and a 1974 fender twin amp. i dont know what the lifespan would be as long as they are working properly and the ps caps are not leaking , popping or buldging.
Title: Re: Power amp life expectancy
Post by: Keith Broughton on May 31, 2017, 07:30:44 am
I have three Crown CE4000's that are around fifteen years old and doing 30 to 40 gigs a year that are in excellent condition and still working great.

Would you trust using them for another five years?

 Is there a practical lifespan for power amps?

Scott
If they are working well, keep using them.
Even if you have to repair them, it can still be cheaper than buying new ones.
Title: Re: Power amp life expectancy
Post by: Stu McDoniel on May 31, 2017, 08:01:01 am
I have three Crown CE4000's that are around fifteen years old and doing 30 to 40 gigs a year that are in excellent condition and still working great.

Would you trust using them for another five years?

 Is there a practical lifespan for power amps?

Scott
Electrolytic Caps have a shelf life and they start to dry up and change value with age. 
Heat can age them fast.   There are people who completely re-cap everything from amps, to consoles
etc.   Just keep this in mind.
Title: Re: Power amp life expectancy
Post by: scottstephens on May 31, 2017, 09:55:40 am
Scott,

   I have 2 Crown MA amps(1200, 2400) that were built in 1988 and are still kicking hard, but only see limited duty these days. Partly because the rack is so heavy, however. Dust and dirt are the biggest enemies. If you can, remove the covers and give them a good blowing out and if they have them, clean the filters so air flow isn't restricted. But in the end, if you aren't completely happy, replace them one at a time with something on the same level or better. Peace of mind is priceless.

scott
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on May 31, 2017, 10:27:32 am
Trust but verify.... Probably not a bad idea to plan for replacement eventually and carry at least one safety back up...  Use them till they stop, but trust depends on what happens (to you) if they fail?

Amplifier technology has continued to advance, so modern amps are smaller, lighter and cheaper. A cheap back up may be surprising.

JR
Title: Re: Power amp life expectancy
Post by: TJ (Tom) Cornish on May 31, 2017, 10:44:59 am
... modern amps are smaller, lighter and cheaper...
Smaller and lighter maybe, but in my experience they haven't gotten cheaper (at least over the last 5 years - I realize that 30 years ago prices/watt were higher).  Behringer and possibly Peavey/Crest excepted, the newer amps are more expensive than similar products a few years ago, largely because of the "black box" mentality (overall a good thing) requiring you to buy matching amps to speakers.  Even mid-tier amps like the QSC PLD series are more expensive than the prior PLX.

TJ "my amp rack is worth more than my car" Cornish
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on May 31, 2017, 10:51:24 am
Smaller and lighter maybe, but in my experience they haven't gotten cheaper (at least over the last 5 years - I realize that 30 years ago prices/watt were higher).  Behringer and possibly Peavey/Crest excepted, the newer amps are more expensive than similar products a few years ago, largely because of the "black box" mentality (overall a good thing) requiring you to buy matching amps to speakers.  Even mid-tier amps like the QSC PLD series are more expensive than the prior PLX.

TJ "my amp rack is worth more than my car" Cornish
My reference frame is from last century when I was an amplifier product manager. So maybe scrape the cobwebs off my response...

Yes, back in the day $1/watt used to be cheap.  ::)

JR
Title: Re: Power amp life expectancy
Post by: Thomas Le on May 31, 2017, 10:52:29 am
Over at my church; there's a rack of MA2400's for tops, 3600VZ's for subs, and XTi2000's for wedges for the occasional weekend outside pavilion events. Still tickin'.
Title: Re: Power amp life expectancy
Post by: Tim McCulloch on May 31, 2017, 11:22:45 am
Scott, at one point we had over a dozen CE4000.  We sold most of them off to purchase XTi6002 but still have 4, I think.  We use them to power passive monitors and distributed SoS rigs.  We have one unit that needs 'jump start' and in spite of going to our Dr. Amplifier we've never found the cold solder joint.  At this point the memory is a little hazy but I don't recall ever needed to send one to Crown for service.

I suspect your CE4000 still has another 5 years left in it, maybe more.
Title: Re: Power amp life expectancy
Post by: Mike Caldwell on May 31, 2017, 12:21:04 pm
For what it's worth the CE4000 was by far the best one in the CE series. There a completely different amp than the 1000's and 2000's.
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on May 31, 2017, 02:03:05 pm
For what it's worth the CE4000 was by far the best one in the CE series. There a completely different amp than the 1000's and 2000's.
Yes, the CE1000/2000 are just poorly repackaged (using SMD) DC300 designs. I would have advised planting those directly in the nearest dumpster... 

That said carrying a backup for CE4000s that old seems prudent. Amps break, even good ones, and old ones are often harder to fix, or not worth fixing.

JR
Title: Re: Power amp life expectancy
Post by: Scott (Abrahamson) on May 31, 2017, 08:02:23 pm
Sorry, long post.

I have a CE2000 that died about five years ago that I haven't got the heart to pitch or repair.

The CE4000's get blown out but I have not taken them apart to check the capacitors. It sounds like a visual inspection would be prudent.

They got throttled this weekend the most ever since I have had them.

What I had booked was a local kids fundraiser with a local DJ and a couple of MC's with some dancers at a ball room at our local events center.

When I get there I discover it is in one of the main halls at 250'x200'x35'. Oh, and by the way there were two more national Dj acts and a MTV Hip Hop rapper/dancer video award winner. Oh, and I need to provide video feeds for live streaming and video archive.

At this point I am getting a bit nervous. I am by myself. I have a XR18 for foh with an iPad. I have four Community SLS920's over four dual eighteen cabinets powered by three CE4000's all ground stacked for video sight lines.

The promoter knew my system so, oh well, I'll just do the best job that I can.

I have four Eons on one mix across the front of a fifty foot stage and there will be up to seventy five dancers, and the DJ's are 20' behind the monitors. It gets even better, I have two $80 wireless mics for the national talent.

The talent arrives for sound check, and I all ready had the monitors set to stun so they were happy. Everyone was impressed that foh was an iPad and I could easily move from person to person to set levels.

Back 75' at foh with management I bring up the mains and start shaking the platform we are on. The vocals are clear and clean and I am not in the red, but right at my system's limit. Big smile and fist bump and a 'sounds great". So far so good. I have five hours of non stop hip hop dance music to survive.

I am absolutely running the snot out of my system, harder than ever before. I go up and check the power amps and the tops never overloaded, the subs only occasionally.

After five hours of abuse I go to shut down the amps and feel behind them and they are warm, though not as warm as I would have expected.

At the end of the night the national guys were happy as well as the promoter so I dodged a bullet.

If the capacitors in the amps are what goes bad, is there a performance boost by changing capacitors to a better quality or different value?

Thanks...Scott





Title: Re: Power amp life expectancy
Post by: Tim McCulloch on May 31, 2017, 08:21:06 pm
After five hours of abuse I go to shut down the amps and feel behind them and they are warm, though not as warm as I would have expected.

At the end of the night the national guys were happy as well as the promoter so I dodged a bullet.

If the capacitors in the amps are what goes bad, is there a performance boost by changing capacitors to a better quality or different value?

Thanks...Scott

Should original parts be unobtanium the biggest challenge will be finding correct-value replacements that physically fit the space available.

I used a CE4000 to replace a Crest 8001 on subwoofer duty.  The Crests were Pin 3 hot so I cut up a mic cable and wired it to the terminal strip on the CE so I'd get matching polarity with the rest of the Crest amps.  I didn't hear any difference but there were a big pile o' subs so it would have needed a big difference to stand out.  The CE4000 survived subwoofer duty on a 5 hour hardcore/metal show and I think that particular amp may be one of the 4 we still have.

Other than a visual inspection of the PSU caps for swelling or leakage I doubt there's much to worry about at this point.  You might call Kevin Gring at Crown and chat him up about whatever age related failures might await you, but I suspect you'll still be using your CE4000 when I retire...
Title: Re: Power amp life expectancy
Post by: Stu McDoniel on May 31, 2017, 09:04:48 pm
Sorry, long post.

I have a CE2000 that died about five years ago that I haven't got the heart to pitch or repair.

The CE4000's get blown out but I have not taken them apart to check the capacitors. It sounds like a visual inspection would be prudent.

They got throttled this weekend the most ever since I have had them.

What I had booked was a local kids fundraiser with a local DJ and a couple of MC's with some dancers at a ball room at our local events center.

When I get there I discover it is in one of the main halls at 250'x200'x35'. Oh, and by the way there were two more national Dj acts and a MTV Hip Hop rapper/dancer video award winner. Oh, and I need to provide video feeds for live streaming and video archive.

At this point I am getting a bit nervous. I am by myself. I have a XR18 for foh with an iPad. I have four Community SLS920's over four dual eighteen cabinets powered by three CE4000's all ground stacked for video sight lines.

The promoter knew my system so, oh well, I'll just do the best job that I can.

I have four Eons on one mix across the front of a fifty foot stage and there will be up to seventy five dancers, and the DJ's are 20' behind the monitors. It gets even better, I have two $80 wireless mics for the national talent.

The talent arrives for sound check, and I all ready had the monitors set to stun so they were happy. Everyone was impressed that foh was an iPad and I could easily move from person to person to set levels.

Back 75' at foh with management I bring up the mains and start shaking the platform we are on. The vocals are clear and clean and I am not in the red, but right at my system's limit. Big smile and fist bump and a 'sounds great". So far so good. I have five hours of non stop hip hop dance music to survive.

I am absolutely running the snot out of my system, harder than ever before. I go up and check the power amps and the tops never overloaded, the subs only occasionally.

After five hours of abuse I go to shut down the amps and feel behind them and they are warm, though not as warm as I would have expected.

At the end of the night the national guys were happy as well as the promoter so I dodged a bullet.

If the capacitors in the amps are what goes bad, is there a performance boost by changing capacitors to a better quality or different value?

Thanks...Scott
Let me make if perfectly clear that a failure in any electronic device could be a number of components or a component.  My post was to inform that Electrolytic caps in devices 15years or beyond might be suspect.
Caps that are subject to a LOT of heat can change value and lead to failure even sooner.
For all you know it could be output transistors in your amp that failed.
Title: Re: Power amp life expectancy
Post by: James A. Griffin on May 31, 2017, 10:15:41 pm
Would you trust using them for another five years?

Good amps are durable.

Back in the day (Late 70's) when I worked at a recording studio, our monitors were powered by Crown DC150's and DC300's.     I don't think they were turned off for more than 5 or 6 short maintenance periods for the 6 years I was there.  No issues.

When I ran my own studio for 10 years,  some of the speakers were powered by Hafler Pro1200's that I put together from the kit..  Again, no issues for the 10 years they ran.    One of the Hafler's builit in 1982 still sits in the rack in my editing / mixing room and still runs when needed.  (mostly using powered speakers now)

Yea, life on the road is harder on amps than in the studio, but the point is, well-treated amps are durable.
Title: Re: Power amp life expectancy
Post by: Jeff Bankston on June 01, 2017, 12:27:07 am
I know of a major tour sound company that still has some early 80's QSC 3800 amps they use. I have dibs on them whenever they decide to sell them, that is IF they decide to sell them. The head guy told me why would they spend money to replace something that works great and is extremely reliable. They have an in house QSC amp tech.
Title: Re: Power amp life expectancy
Post by: Tim McCulloch on June 01, 2017, 02:01:18 am
Let me make if perfectly clear that a failure in any electronic device could be a number of components or a component.  My post was to inform that Electrolytic caps in devices 15years or beyond might be suspect.
Caps that are subject to a LOT of heat can change value and lead to failure even sooner.
For all you know it could be output transistors in your amp that failed.

His CE4000 is still working, it was his CE2000 that went to Nonfunction Junction.  With that model there are several possibilities but I think your choice of output transistors is a good one.  I don't think the 2k is worth repairing.
Title: Re: Power amp life expectancy
Post by: Tim McCulloch on June 01, 2017, 02:04:06 am
Good amps are durable.

Back in the day (Late 70's) when I worked at a recording studio, our monitors were powered by Crown DC150's and DC300's.     I don't think they were turned off for more than 5 or 6 short maintenance periods for the 6 years I was there.  No issues.

When I ran my own studio for 10 years,  some of the speakers were powered by Hafler Pro1200's that I put together from the kit..  Again, no issues for the 10 years they ran.    One of the Hafler's builit in 1982 still sits in the rack in my editing / mixing room and still runs when needed.  (mostly using powered speakers now)

Yea, life on the road is harder on amps than in the studio, but the point is, well-treated amps are durable.

I built a Hafler DH 1200 for my first "real PA", low section.  I still have it powering my home stereo (Soundcraftsmen CX4000 Preamp, JBL 4408 speakers).
Title: Re: Power amp life expectancy
Post by: Mike Caldwell on June 01, 2017, 02:24:19 am
I built a Hafler DH200 power amp than ran the bullet tweeters in an early system. The amp lives on today in my living room powering the Tannoy DMT10 II studio monitors I use for my stereo. I did need to re cap the amp a few years ago, one channel started sounding really thin. The power supply caps were fine, I just replaced all the electrolytics on the amp boards and re biased the amp.
I use a Hafler DH110 preamp with the amp and I re-capped it at the same time as the amp. Even though the pre amp was fine since I was in the re-capping mode I just did it as well.
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on June 01, 2017, 10:16:36 am
His CE4000 is still working, it was his CE2000 that went to Nonfunction Junction.  With that model there are several possibilities but I think your choice of output transistors is a good one.  I don't think the 2k is worth repairing.
+1

amps used for SR get more physical stress, and dubious mains power quality, than sitting in a living room or recording studio. 

Yes, common fault in bipolar power amps is shorted output devices. If you have more time than money you might try fixing (the 2000) yourself but perhaps open it up and take a look around first. IIRC one weakness in that particular re-packaging job was using modest sized SMD emitter degeneration resistors that tend to burn holes in the PCB when the power devices fail short circuit.  :o The design was similar to old DC300 (quasi-complementary) so reasonably reliable but IMO not very hifi. The well respected CE4000 was an entirely different animal, and why they were all in the same one amp series family remains a head scratcher? 

JR

PS: My living room amp that I designed myself back in the early 70s still works, or did last time I turned it on (yawn).
Title: Re: Power amp life expectancy
Post by: Jean-Pierre Coetzee on June 06, 2017, 05:01:49 pm
All the research I've done has shown that power cycling equipment is about as bad for them as leaving them on so...
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on June 06, 2017, 06:35:58 pm
All the research I've done has shown that power cycling equipment is about as bad for them as leaving them on so...
Research where?

I have actually thought about this over the years. Some products in the fixed instal market are designed to be turned on and left on...In one wall mount amp I made the cooling fan 3 speed, so when it was resting it could really rest.  8) Moving parts like fans clearly have a life related to hours of operation. Solid state devices not so much. There are mechanical stresses related to thermal cycling (heating up when on, and cooling off when off). Reservoir capacitors over time and temperature can lose electrolyte and degrade. Modern capacitors seem a lot better than they were last century, and we can also specify higher temperature caps for hotter ambient applications.  These are all well understood and manageable factors. One wild card in this "on vs cycled on/off" analysis is quality of the mains power... if rouge power surges occur often, like weather related lightning strikes, maybe off is better.   

I actually wrote about this question for my magazine column back in the 80s. As I recall the light bulb on my desk burned out while I was writing the column.  :o  I don't have any incandescent light bulbs left these days.

JR
Title: Re: Power amp life expectancy
Post by: TJ (Tom) Cornish on June 07, 2017, 08:33:10 am
All the research I've done has shown that power cycling equipment is about as bad for them as leaving them on so...
That's not been my experience.
Title: Re: Power amp life expectancy
Post by: Ivan Beaver on June 07, 2017, 04:02:02 pm

I actually wrote about this question for my magazine column back in the 80s. As I recall the light bulb on my desk burned out while I was writing the column.  :o  I don't have any incandescent light bulbs left these days.

JR
I don't think I have ever seen an incandescent bulb burn out while it was on.  But I could be wrong-or just lucky-or unlucky. :-\

They always seem to go out when power is first applied and the filaments are cold-pulling extra current through them.

However I have had florescent and LED lights go out while being on.
Title: Re: Power amp life expectancy
Post by: Ivan Beaver on June 07, 2017, 04:04:45 pm


PS: My living room amp that I designed myself back in the early 70s still works, or did last time I turned it on (yawn).
The old Peavey mixer under my desk top worked the last time I plugged it in-which was right before I put it under the glass.  That was a couple of years ago.-but still in this decade.
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on June 07, 2017, 05:08:06 pm
I don't think I have ever seen an incandescent bulb burn out while it was on.  But I could be wrong-or just lucky-or unlucky. :-\

They always seem to go out when power is first applied and the filaments are cold-pulling extra current through them.

However I have had florescent and LED lights go out while being on.
Just lucky I guess... ;D Actually that has been my experience too, except for the one time I was writing about exactly that.  ::)

 I thought it was an interesting outlier and I mentioned it in my column (30 years ago). Yes, we almost forget how fragile the incandescent lamps are. Remarkable for what they were, but ancient history now.

JR
Title: Re: Power amp life expectancy
Post by: Bob Leonard on June 07, 2017, 05:20:59 pm
I really wish people would stop stating that the "capacitors" in an amplifier are usually what fails. Quality caps almost never fail without a related failure in another component. Electrolytic capacitors dry out with age, but you're usually talking about 10-15 years, and failing electrolytic capacitors will always show an outward sign of failure, i.e. bubbling, swelling, exploding. Caps that are not polarized, Mylar, ceramic, orange drop, etc. will last many more years than a polarized electrolytic, however, they can be easily checked by lifting the grounded leg and checking voltage. There should be no B+.

Anyway, all of the components should be metered and checked starting with the power supply and the caps associated. Then, if the voltage(s) is/are correct and no voltage is passing in the wrong direction it's time to trace further. Good checks mean less wrecks.   
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on June 07, 2017, 06:00:05 pm
I really wish people would stop stating that the "capacitors" in an amplifier are usually what fails.
Who said that?
Quote

Quality caps almost never fail without a related failure in another component.
a shorted diode can cook a cap faster than squat... Elevated ambient temperature (like inside a power amp) can speed up deterioration.
Quote
Electrolytic capacitors dry out with age, but you're usually talking about 10-15 years,
OP is asking about an amp that old...
Quote
and failing electrolytic capacitors will always show an outward sign of failure, i.e. bubbling, swelling, exploding.
How about leaking ? (like from their "bung hole"... actually a pressure relief vent in the rubber bung).
Quote
Caps that are not polarized, Mylar, ceramic, orange drop, etc. will last many more years than a polarized electrolytic, however, they can be easily checked by lifting the grounded leg and checking voltage. There should be no B+.

Anyway, all of the components should be metered and checked starting with the power supply and the caps associated. Then, if the voltage(s) is/are correct and no voltage is passing in the wrong direction it's time to trace further. Good checks mean less wrecks.

In (solid state) power amps the output devices are the most likely suspects (fail short circuit). But anybody spending enough time in the trenches will see many different components fail.

JR
Title: Re: Power amp life expectancy
Post by: Ivan Beaver on June 07, 2017, 07:01:47 pm
I really wish people would stop stating that the "capacitors" in an amplifier are usually what fails.
Totally agreed.

I was a bench tech for many many years.

With the exception of some old (60s) fender amps, and tantalum caps, a capacitor failure is almost non existent.

Yes I have replace a few, but not enough to even worry about-in my opinion.

I think in most cases, the people saying it are just passing it along trying "be smart" because they heard some tech mention it and it sounds cool.

Agreed the JR, the output devices are BY FAR the biggest failure point in amplifiers.

Guess what-they are the things that are working the hardest also.
Title: Re: Power amp life expectancy
Post by: Ivan Beaver on June 07, 2017, 07:03:58 pm
a shorted diode can cook a cap faster than squat...
But if you keep the proper sized fuse in the amp-it will blow, making the strain on the caps to a minimum.

I have replaced a good number of bridge rectifiers in amplifiers also.  Mostly on the cheaper amps-trying to same a few cents.
Title: Re: Power amp life expectancy
Post by: Scott (Abrahamson) on June 08, 2017, 09:49:44 pm
I guess I will give the CE4000's a good looking over and keep them if there are no major issues. I am 62 and I don't plan on schlepping gear around for more than about five more years, so hopefully we both hold out.

If an amp goes down I can easily run on two amps since I am biamping in stereo.

Here is a question for the amp experts:
On most gigs I run four tops over two dual 18's. The four tops are on amp #1 in stereo. The two subs are on channel one on amps #2 & #3. I have my subs wired with NL8's so if I need the second pair of subs I can jumper off of the first pair and pick up power for the second pair from channel two of amps #2 & #3. Each sub on a channel.

My thinking being that I have power supplies from two amps on subs instead of one. And both amps are getting the same amount of use at half the load.

On one hand it makes sense to only use one amp on subs and keep the third in reserve, but my gut tells me three running amps gives me options and security.

My question is, is it better to use one amp with both channels driven or two amps with one channel each driven?

Thanks for all the great responses....Scott
Title: Re: Power amp life expectancy
Post by: Ivan Beaver on June 09, 2017, 07:19:06 am

On one hand it makes sense to only use one amp on subs and keep the third in reserve, but my gut tells me three running amps gives me options and security.

My question is, is it better to use one amp with both channels driven or two amps with one channel each driven?

Thanks for all the great responses....Scott
It depends on how hard you are running the amp.

If you are pounding away at the limits, then use 2 amps.  But if you are not hitting the clip lights, I doubt you would be able to hear the difference 2 amps would make.

But I have not tried it on the CE4000, even though I installed quite a few of them back when they were new.
Title: Re: Power amp life expectancy
Post by: John Roberts {JR} on June 09, 2017, 10:34:28 am
I guess I will give the CE4000's a good looking over and keep them if there are no major issues. I am 62 and I don't plan on schlepping gear around for more than about five more years, so hopefully we both hold out.

If an amp goes down I can easily run on two amps since I am biamping in stereo.

Here is a question for the amp experts:
On most gigs I run four tops over two dual 18's. The four tops are on amp #1 in stereo. The two subs are on channel one on amps #2 & #3. I have my subs wired with NL8's so if I need the second pair of subs I can jumper off of the first pair and pick up power for the second pair from channel two of amps #2 & #3. Each sub on a channel.

My thinking being that I have power supplies from two amps on subs instead of one. And both amps are getting the same amount of use at half the load.

On one hand it makes sense to only use one amp on subs and keep the third in reserve, but my gut tells me three running amps gives me options and security.

My question is, is it better to use one amp with both channels driven or two amps with one channel each driven?

Thanks for all the great responses....Scott
I am inclined to agree that splitting the load between the amps will allow them to operate cooler (a good thing for amps). If one fails you will get better warning than if it failed while waiting to be used as the back-up. 

JR