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[Alan Hewlett]

Hello!! Long time reader, fairly new poster.

We our main auditorium sound system is driven by three Crest Audio CA18s, one for the sub-woofers (channel A & B), one for the mid-lows (channel A & B) and one for the mid-highs (channel A) and highs (channel B). These amps are over 5 1/2 years old and get fairly constant use. Over the last 4 months, all three have burned up their power supply sub-assemblies and have been repaired. I do not know how much long these may last, so I'd like replace them. I also like to go with something other than Crest. What would be a comparable replacement that would deliver the same output power (900W per channel), comparable sound quality and also be cost efficient to a church on a somewhat tight budget? Thanks for any suggestions you may have....

[Aaron McQueen]

Quote:

Over the last 4 months, all three have burned up their power supply sub-assemblies and have been repaired.

I would first find out why this happend.  Were the amps in a well ventelated area?  Was there any dust?  Did the fans fail? Power surges? etc.

Once you've found the problem, you may or may not want to stay with what you have.  If you decide to switch I would look at the QSC Audio amps.  Don't forget that all amps are differnt and you will have to reset your gain structure for the new amplifiers.

[Brad Weber]

Can you tell us a little more about how the system is configured and what the amps are driving?  Knowing whether the amps are run stereo, bridged or parallel and whether they are driving an 8 Ohm, 4 Ohm or 2 Ohm load will certainly affect what is appropriate.

I agree with Aaron that you really need to try to determine what caused the failures.  It would be unusual for all the power supplies to simply start failing 5 years after the amps were installed, unless something happened like discontinuing cleaning the filters or changing the ventilation or adding other 'unfriendly' loads on the circuits powering them.  If there is a problem you will probably end up simply transferring the problems to the new amps.

[David Sumrall]

Hey Alan,

A little to add here.

Before anyone can help recommend and amp as said before more info is needed.

You may want to do a little research and find out if there are any known issues with your amps.

What exact boxes are used in what exact configuration?

Do you know for sure that these amps were in fact the correct solution for the boxes, number of boxes and load.

Has the system bin run correctly? Or has it been pushed too much trying to get a bigger sound then it is set up for?

Are you running aux fed subs and pushing the low end level beyond the normal balance?

If they were not that could shorten life cycle.

Do you know that eq and processor settings are correct?

Is the bass eq on a lot of channels boosted? Is it boosted on the graphic or paremetric for the house eq?

Some of these might show systems of not having enough low end in the system originally and trying to boost it or push it etc.

Have you checked your power?? Is it clean? Is it correct? Is is staying with the recommended range for the amps? Some equipment can run fine under 120v but some pieces have lower tolerances. In Florida we have brown outs and voltage drops all the time. Our 4k for example can run fine down to around 107 but lower and it has issues.

Has anything been added to the power that the amps have been using to would cause a draw problem?? ie another amp, stage power.

Have the amps that have been dying on you been in use in the same place all the time? Or have they been shifted around as one dies and then the problem shows up again? For example did another one get moved over to run the speakers that the bad one used to run?

Do you know for sure that your system after the amps are fine?
Cables, in speaker crossovers, connections, and drivers. Something else may be busted down the line and causing you a problem that you did not know about, with the only symptom you know so far being the amps issues.

Ok you asked for amp recommendations..

This list is not complete, and replacement will be more expensive then repair.

Lab Gruppen, d&b, etc on the high end side-

The Labs are light and sound awesome. Many companies in the states and around the world have been copying them for a bit.

d&b- great sounding, tons of head room, built in dsp(delay, crossover, eq etc built in) can run with settings for their boxes or in linear mode for others.

Crown-Macro Techs if you can find them

Yamaha- their new amps a much more in line with their really old stuff in robustness.

QSC- good too as are others not listed.

Good Luck!

David Sumrall
Technical Director/A1
First Baptist Orlando

[Alan Hewlett]

Thanks for the suggestions! After talking to several repair techs locally when I had the amps fixed, and a tech at the Crest Service center, it appears that this particular power module "burn out" may be a fairly common problem with the CA18. We have six CA12s and two CA4s for stage sound in the same area, same power feeds, same maintence, etc. Not a bit of trouble with any of them. That's why I'm a bit suspicious of the CA18 and why I'm leaning towards another supplier. I've only been working at this facility a bit over six months, so I need to crawl up in the rafters and see what types of specific speaker cabinets, impedence, etc I'm dealing with (they're EAW cabinets, but don't know the models). Thanks again for the info, I appreciate it......

[Ira White]

I've been real happy with the Yamaha P7000S models I've used with 1100 watts per channel @4 ohms. If you want to go network, they have the Tn series but the smallest is the T3n at 1400 watts per channel.

[Gary Creely]

 

[Brad Weber]

Gary Creely wrote on Sat, 23 June 2007 01:14

Alan, I noticed many replies hesitate to give recommendations before they know exactly what you are doing, how cautious of them. I will put caution to the wind and actually give you a direct answer.

Coincidentally, it also appears that those being cautious are consultants and church representatives while those recommending specific models seem to be dealers for the models they recommend.

I would suggest looking at some of the other forums here at PSW and search for threads regarding some of the current options.  Also keep in mind that some newer amps incorporate internal DSP, a benefit if you do not currently have signal processing but possibly a liability or unnecessary expense if you already have signal processing.

As an example of the impact of the specific configuration, the I-T4000 does match well against the CA18 for many, but not all (such a 4 Ohm bridge), modes.  So it may or may not be a good option.

[Gary Creely]

Brad,

Are you suggesting that I recommend only amps that I deal? The truth is I select the dealership based on there offering. I deal both crest and crown (I may be adding QSC in place of Crest),so I am not trying to hype a specific line because I deal it. As far as consultants having some sort of pure unbiased view of gear, I would suggest that is false. In fact some of (not all)the most under informed people on gear people I have met have been consultants(because knowledge in some cases is all theoretical). I am a design build guy, I am both behind the screen as well as the occasional install. I use amps I don't deal when the application calls for, so I take a little offense at that insinuation.

As far as the I-T4000 matching up, modern current switching amps are not going to perfectly match up with an old amp, but you and I both know a couple watts one way or the other is not a significant issue.

The DSP issue is an interesting one. My contention is DSP on board is going to be the standard( if nothing else for compression). In crowns line up less and less of their offerings lack DSP on board. I would say the cost factor is not a big deal, and can not think of why it would be a liability (unless it fails).

[Aaron McQueen]

Quote:

The crown I-tech amps are arguably the best amps on earth.

This comment is probably why Brad responded the way he did.  After reading it, I then click on your website, saw that you were a Crown dealer, and came the same conclusion as Brad.  Just be carefully when recommending products that you are a dealer for.  It makes it worse when you make generalizations like the one above.  I put Ira's post in the same category.

Quote:

The DSP issue is an interesting one. My contention is DSP on board is going to be the standard( if nothing else for compression). In crowns line up less and less of their offerings lack DSP on board. I would say the cost factor is not a big deal, and can not think of why it would be a liability (unless it fails).

I think Brad was saying that the OP may already have a DSP in place.  Adding an amp with DSP cost more and creates another point of failure and/or possible confusion.

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