Crest repair center needed

Re: Crest repair center needed

Alan Sledzieski said:
JR,

Why does this line of amps put more power out when bridged into 8 ohms vs. 4 ohms? Whats different about them?

Thanks

Macro-Tech i Series
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It Looks like a design decision, to not provide the extra power supply current output and heat sink dissipation required to support 2 ohm operation longer than 20 mSec.

With unlimited current and heat sinks, the 5000i's 2500W 4 ohm power would increase to roughly 5000W, but per the data sheet it only increases to 3000W, so that is current limited. Further it is dissipation limited to only do that for 20 mSec. The 9000i comes closer to a double (2800 increases to 4700), so puts out more current than the smaller amp, but still for only 20mSec.

In bridge mode, you are getting the power output of both channels combined together into one load. While the 5000i spec looks straightforward with 2500+2500=5000, the 9000i and 12000i 8 ohms bridged data looks a little funny. The 9000i 8 ohm bridged power is probably time limited similar to their 20 mSec peak power spec, and the 12000i's 9000W number also suggests a short term burst power spec.

Note: Burst power can be useful for reproducing full range material, only with a band passed sub amp, being driven hard might you bump into the 20mSec limitation, but to do that you would have to be working it very very hard (less than 3 dB crest factor), so I suspect they work OK for "most" sub applications too.

JR
 
Alan Sledzieski said:
JR,

so I suspect they work OK for "most" sub applications too.

The ok scares me, lol.
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Base on my extensive experience with the new MacroTech HD amps, I strongly believe if you think that the amplifier is the sound quality problem in your signal chain you are probably not very good at troubleshooting and systems analysis. Or you have a wicked case of confirmation bias.
 
Re: Crest repair center needed

Bennett Prescott said:
Base on my extensive experience with the new MacroTech HD amps, I strongly believe if you think that the amplifier is the sound quality problem in your signal chain you are probably not very good at troubleshooting and systems analysis. Or you have a wicked case of confirmation bias.
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What are you talking about? I never said I had a sound quality issue, I'm having reliability issues.
 
Re: Crest repair center needed

Alan Sledzieski said:
What are you talking about? I never said I had a sound quality issue, I'm having reliability issues.
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My "OK" comment was not referring to reliability which is only loosely associated with program material, but whether the short term nature of the burst power would be apparent in use on subs. I had to qualify my response to "most" since A) I am not personally familiar with the crown amps, and B) some program material is silly bass-heavy (dance/trance/nuance).

There is a mild association with heat and reliability. MTBF (mean time between failure) doubles for every 10'C drop in operating temperature, but I suspect most amp failures are not remotely near end of life general deterioration.

Reliability of power amps is dominated by design rigor. Most amp brands with recognizable names have tons of experience with where the weak links are in their designs (from decades of service experience) and every new generation gets stronger in an rational world.

Secondary effects that can impact reliability, are execution of that design, that can be compromised by inferior components or workmanship, and conditions in use. Elevated ambient temps, or out of tolerance mains voltage could have an impact.

I am not smart enough to know what your particular amps are suffering from, if they are suffering from anything more than normal wear and tear. If they are out of warranty, this isn't exactly infant failures.

Again good luck with your drama.

JR
 
Re: Crest repair center needed

The couple of times that I have sent Crest amps in for repair out of warranty they were taken care of quickly and the costs were reasonable to return them back to service. I always prefer to send amps in directly to the mfg whenever it makes sense. No one knows the product better.

I'd suggest biting the bullet and sending the amp/s in need of repair to Crest directly and then off-loading the whole lot afterwards in order to move to something with a warranty still in effect.
 
Re: Crest repair center needed

Josh Ricci said:
The couple of times that I have sent Crest amps in for repair out of warranty they were taken care of quickly and the costs were reasonable to return them back to service. I always prefer to send amps in directly to the mfg whenever it makes sense. No one knows the product better.

I'd suggest biting the bullet and sending the amp/s in need of repair to Crest directly and then off-loading the whole lot afterwards in order to move to something with a warranty still in effect.
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Yes. This.

If you don't like the amplifiers, I'd recommend sending any broken ones in to Crest and getting them fixed.

Then sell them all and get something you feel like you can trust.

Or, you can just keep bitching about it on an internet forum... whatever you think is going to help you the most.

Incidentally, I've still not received any messages from anyone who has been having reliability issues. However, I did speak with a couple associates over the last weekend and I know that there are a couple good sized sound reinforcement companies around here that have invested quite heavily (I'm talking about literally hundreds of amplifiers) into the Pro 200 series Crest Audio amplifiers and have not been having any problems with them at all. In one case I know they have displaced racks of Crown MA5000 and MA5002 amplifiers to provide lighter sub racks. Also, they have threatened to replace the Lab.gruppen FP6400's in another set of racks...

I guess the bottom line here is that you need to have gear that you feel like you can trust. If your current gear doesn't do that for you, you should probably look into what you need to do to get gear you can trust. If you are using this equipment to make money, it needs to be reliable and trustworthy above all else.
 
Re: Crest repair center needed

Alan,
Josh pretty much sums it up in his last post. No offense meant, but I don't have much patience with someone who comes on the interweb crying about poor performance from their chosen tools when they haven't exhausted the resources available from the manufacturer in an effort to get things on track.
 
Re: Crest repair center needed

Got 1 amp back today, both amps had the same tracer in the power supply section blistered, along with no connection from melted solder. 1 amp was worse then the other so he removed some parts and tested them, they checked ok, will assemble on wed.

My other 8200 that went a while back, same issue, along with a few more 8200's that he repaired, same area blistered and lifted.

All these amps were being run bridged into 4 ohms or stereo 2 ohms, so, lots of current and heat on a small tracer.

You can say I'm bitching, but there seems to be a problem here, wouldn't you say?
 
Re: Crest repair center needed

Alan Sledzieski said:
Got 1 amp back today, both amps had the same tracer in the power supply section blistered, along with no connection from melted solder. 1 amp was worse then the other so he removed some parts and tested them, they checked ok, will assemble on wed.

My other 8200 that went a while back, same issue, along with a few more 8200's that he repaired, same area blistered and lifted.

All these amps were being run bridged into 4 ohms or stereo 2 ohms, so, lots of current and heat on a small tracer.

You can say I'm bitching, but there seems to be a problem here, wouldn't you say?
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Well there is a problem if its happening to a lot of people, So far this is the only complaint I have read about with your issue. What we need to find out is what is causing this issue for you. Again did you call crest and ask them if they have had others with the same type of problem as you? or even ask josh, I am sure he will give you a straight up answer.
 
Re: Crest repair center needed

Jack Keaton said:
Well there is a problem if its happening to a lot of people, So far this is the only complaint I have read about with your issue. What we need to find out is what is causing this issue for you. Again did you call crest and ask them if they have had others with the same type of problem as you? or even ask josh, I am sure he will give you a straight up answer.
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I have not talked to any one at crest, I just deal with the authorized dealer by me, the amps come in with the same problems in the same area. As far as it goes for me, I don't need to talk to crest, they need to talk to repair shops and see what the failures are, I just post facts that I have, I'll get a pic up of the area, crest can go from there.

I said it before I like the way they sound, I just have no faith on a switching amp on bottom end I guess, they can't take the heat??
 
Re: Crest repair center needed

Jack

This issue is not only happening to me, other 8200's have come in, same area has this issue, 4 ohm bridged or 2 ohm stereo. I have not had a issue with these amps on my horns, mids, or monitors, just on bottom end. According to my repair man, thats his findings also, just when pushed on bottom end. Poof.
 
Re: Crest repair center needed

Vinny D'Agostino said:
I just received a brand new 8200 the other day, we will see how it goes!
I do not run my amps bridged, and on subs only to 4ohms per channel, so maybe they will fair better...
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4 ohms is a lot easier on the amp, I would say you will be fine, plus you have a warranty!!!

These amps sound great, just that issue on the tracer and the bridge going out at times. Your biggest fear is when the warranty is out and you burn the board, being that the whole thing is on one board, you basically throw it away. If at least crest made it in 2 seperate sections, power supply on 1 board and amp section on another.
I picked the other amp up today, I talked to the tech for a while, he did comment that there are good components being used in this amp, said there is the common issue where my amp had the issue. But the biggest complaint is, everything on 1 board, when its out of warranty and it burns up, your into a very expensive repair. basically, buy a new one.
 
Re: Crest repair center needed

Alan Sledzieski said:
Josh,

Anyone else having these issues?
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Hi Alan,

You are the only person I've heard from who is having this kind of problem.

However, please note that I am NOT "Crest Audio Factory Repair"... I work for MediaMatrix Technical Services... the repair guys are on the other side of town. So, I don't really have a very good database of information to pull that statement from. Really, the best feedback I get is in forums, like this one, where people, like you, express their frustrations. I like to try to help these people when I can because I know how irritating and frustrating it can be when trying to deal with a large "face-less" corporation.

Anyway, after asking, in this very thread, for people to get in touch with me if they are having trouble with their amplifiers, I didn't receive a single PM from anyone. I even asked some friends that I have who have racks of their own amplifiers if they were having trouble with them and all of them indicated that they were essentially worry free. But, knowing how a lot of these guys run their systems, I don't think there are very many people who are actually running their amps bridged into 4 ohms. I fully agree with you that if the amps are rated to do it, they should be able to do it all day, every day and it shouldn't be a problem. However, most of the guys I know will run their amps at 4 ohms stereo (or 8 ohms bridged), thus providing the opportunity to switch to 2 ohms stereo (or 4 ohms bridged) in the event that they have an amp die.

I'm going to take that photo you posted in message #54 and show it to some people and ask them why that trace would possibly be problematic on the Pro8200 amplifier. I will be glad to let you know what I find.

Please forward to me in a PM who the Crest Audio service tech is that you have been using. If he has been experiencing a lot of this kind of failure, we would like to know about it.

Thanks!
Josh
 
Re: Crest repair center needed

Josh,

Please tell me what the crest techs say about that trace. Also ask them about the bridge. I'm pretty sure my tech said that trace sees the most current, right from the power supply to the bridge.
 
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