# Plate amp failing, looking for outboard replacement



## Spork (10 mo ago)

So I have Acoustic Research AR-1's and I've had these forever, still very happy with them. For those that do not know about these, they are "3 way" towers with a 15" powered sub built in (Amp inside is a Sunfire or at least their design, 500 watt). 

Couple of old articles for reference, Home theater review, Stereophile

Short story
I'm thinking of just buying an outboard amp(s) and just bypassing the internal amp.

Looking for opinions. Note about the subs: I've pulled the subs to check and they are 4 ohms each


Crown XLS 2502 - running in stereo, ran to each tower sub.
Good: Good power, good price, saves in space, with a relay I can turn the amp on and off with receiver 
Bad: will not fit in cabinet due to mounting ears unless I modify the amp mounting ears

2, Dayton Audio SA1000 - 1 for each tower sub
Good: greater tuning options, no modification required to fit into cabinet, 
Bad: a little bit more money because I have to buy two

Long story
I travel sometimes and when I do, I typically unplug things to save some electricity. I came home from a trip and plugged in each tower and I noticed I was getting a low volume buzz out of the one of the AR1's. even if the amp was not being used. Unplugging the inputs from the amp would not get rid of it. After 20 minutes of it being plugged in, it would actually go away. This normally is a power supply cap gone bad. 

About the same time I noticed some strange noise during low frequency. hard to explain but audible from the seating position. I tested the sub with a different sub just in a free air and tried the original sub with a different amp and its without a doubt the amplifier producing the other noises.

I pulled the amp, and ordered the filter caps for the power supply section, even though there was no sign of cap failure, I replaced both of them and it fixed the buzz sound but the other issue still remained. I don't know what's wrong with it. I'm thinking bypassing is the only option. 

I don't know if it would be worth sending them out to anyone to fix


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hate to be a party pooper, but it’s possible the sub amps had some built-in processing. If so, it’s going to be lost with an off-the-shelf replacement. Unfortunately, you won’t know until you sink the cash for the new one.

Regards,
Wayne


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## Spork (10 mo ago)

Wayne A. Pflughaupt said:


> Hate to be a party pooper, but it’s possible the sub amps had some built-in processing. If so, it’s going to be lost with an off-the-shelf replacement. Unfortunately, you won’t know until you sink the cash for the new one.
> 
> Regards,
> Wayne


That had crossed my mind, I was thinking about hooking the amp (the good one) directly into my RTA to see what kind of freq curve its putting out. If it's some type of complex curve I might have to get a miniDSP to get it back to AR's spec....or tune it for better performance.


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## Mr645 (Apr 9, 2020)

Just a suggestion, the XLS-2502 is a serious amount of power. Probably get by just fine with a 1502 or 1002. I replaced a blown Dayton SPA 1200 with the XLS-2502 and the XLS-2502 is far, far more powerful.


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## Spork (10 mo ago)

Mr645 said:


> Just a suggestion, the XLS-2502 is a serious amount of power. Probably get by just fine with a 1502 or 1002. I replaced a blown Dayton SPA 1200 with the XLS-2502 and the XLS-2502 is far, far more powerful.


At first I was looking at the 1502 but I guess they were on backorder. That's what made me look at the 2502. I just looked this morning at it looks like the 1502 is coming available some places now.


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## Mr645 (Apr 9, 2020)

Spork said:


> At first I was looking at the 1502 but I guess they were on backorder. That's what made me look at the 2502. I just looked this morning at it looks like the 1502 is coming available some places now.


I was in the same boat, looking for an XLS-1502, willing to accept a 1002 or 2002 but the 2502 became available. I am using it for a DIY sealed 18" subwoofer and recently added a high pass filter at 18 hz to protect the driver that was being driven to excursion limits with some movies


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## marchewd (Feb 6, 2008)

I just had Daveds50 fix my Elemental Designs LT1300 plate amp. He fixes all sorts of amps for all manufactures. Here is his Facebook page: Daveds50 Electronics - Home | Facebook . His email is [email protected]. I found him through AVS Forum. I was in the same boat as you, but wanted it to repair my plate amp, if it at all possible because I couldn't find a drop in replacement to fit the cutout in my sub and I didn't want to discard the processing/tuning that ED put in that amp to match the drivers. He didn't overcharge to fix the amp and repaired it quickly.


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## Spork (10 mo ago)

@marchewd thank you so much, I will reach out to him.

Where is he out of?


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## RobertR (Jan 23, 2007)

This is really weird. When you said "AR-1", I thought at first you were talking about the original Acoustic Research speaker from the 50s. Talk about having something forever!


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## Spork (10 mo ago)

RobertR said:


> This is really weird. When you said "AR-1", I thought at first you were talking about the original Acoustic Research speaker from the 50s. Talk about having something forever!


Ride or Die 😁


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## los153 (Nov 5, 2006)

If you can get a repair for your plate amp, you may want to consider repairing them both, so that they're matched in parts and balanced for lifetime use. If the repair doesn't work out, and if you're handy with light woodworking, you could consider replacing the plate amps with new ones. Parts Express has lots on offer. I once replaced one in a sub and ended up with better performance afterward. I did have to increase the opening a bit for the new amp to fit - with careful use of a sabre saw and accessing the wiring through the hole for the sub driver - but I was very happy with the results!


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## Spork (10 mo ago)

los153 said:


> If you can get a repair for your plate amp, you may want to consider repairing them both, so that they're matched in parts and balanced for lifetime use. If the repair doesn't work out, and if you're handy with light woodworking, you could consider replacing the plate amps with new ones. Parts Express has lots on offer. I once replaced one in a sub and ended up with better performance afterward. I did have to increase the opening a bit for the new amp to fit - with careful use of a sabre saw and accessing the wiring through the hole for the sub driver - but I was very happy with the results!


I asked this same question to Davids50 electronics in a email but I haven't heard back from him yet


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## marchewd (Feb 6, 2008)

Spork said:


> I asked this same question to Davids50 electronics in a email but I haven't heard back from him yet


I found him over at AVS Forum, not sure if mentioning another forum was against the rules.


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