Optimus MPA 250???

analog addict

Glory or Death!
Is this thing usable at all in audio applications? Does anyone have any experience with them? Here's some additional info from the web...

MPA-250 250-Watt Stereo Public Address Amplifier
(320-2004) Features Faxback Doc. # 51679

Your Optimus MPA-250 250-Watt Stereo Public Address Amplifier gives you
the versatility and power you need in a professional sound system. Its
wide frequency response easily handles amplification of voice and music.
Use it in meeting halls and auditoriums, at sports events, in schools, and
in the office for paging systems - anywhere you need to deliver special
announcements with excellent sound.

The amplifier (if bridged) produces up to 350 watts of clean, powerful
sound with minimum distortion.

Your amplifier includes these features:

10-50,000 Hz Frequency Response

Built-In Cooling Fan - helps protect the amplifier by reducing its
internal temperature.

Two Mounting Options - you can mount the amplifier in a standard
sized audio equipment rack or on a desk,
shelf, or table.

2 lighted VU Meters - measure the amplifier's output for each
channel in decibels.

Left and Right Output - lets you adjust the overall sound level on the
Level Gain Controls left and right channels.

Clipping Indicator - lights if a sound source signal overdrives the
amplifier.

Phones Jack - lets you connect headphones so you can listen
privately.

Bridging Capability - you can combine the amplifier's two channels
and use the amplifier with only one channel,
producing a total of 350 watts.

Meter Range Select Switch - lets you control the meter's sensitivity.

Input Jacks - lets you connect a variety of audio input
sources for music and special effects.

A/B SPEAKER Switches - lets you select the speakers you want to use
with the amplifier.

STEREO/MONO Switch - lets you select the output type; stereo or
mono (bridged).

Binding Post Terminals - lets you easily connect wires directly to the
amplifier.

Switched AC Outlet - lets you power other devices by plugging them
into the back of the amplifier.

Thanks....
 

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I had one of them, WORKS great, The reason i got one is because during sound check to a dance i was about to deejay for i lost my jbl amp (it died). and the only place around to buy anything for a amp was radio shack. So i bit the bullet and bought one. I used it for 2 years with out a problem. Then i bought a new amp a Yorkville CR 5.

Pyle audio is the company that makes these amps for radio shack

http://www.pyleaudio.com/itemdetail...=Pro Audio&cat2=Power Amplifiers&model=PT2000


This is common for radio shack to have a more stable company build pro audio gear for them, here another example of them doing it.

The silver one is PYRAMID and the black one is a Radio shack (nexxtech)

i own a mixer that was made by pyramid but has realistic stamped on it. and that was back in 1988
 

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I wouldn't count on it being a worldbeater, but it's probably a solid amp. 125WPC, 1% THD, $299.99 in the 2002 catalog.

One advantage it has over most live audio amplifers is RCA jacks, so you don't have to worry about fussing with input levels and and balancing.
 
oh it a solid amp, I pounded 4 hour a night, 3 times a month for 2 years not one singal problem. BUT it's no yorkville or JBL amp...it all depends on what your using it for. I only deejayed small to med size venues when i had it.


P.S you must be in the U.S.A Analog Addict, because Optimus is no longer sold in radio shacks here in canada (The source by circuit city) I know my amp was the same thing you got, by mine had Nexxtech on it instead

As for the rca jacks, ya it great for home audio use and all and also for deejays. But people like me who use their's for both deejaying and live audio have to use the XLR or 1/4 plugs, because of the lenght of wire from the mixer board to the amp, i know mine runs about 150 feet, from the stage to about middle part of a school gym (example here)
 
I had one those a few years back. I drove some hpm 100's with it for about a year. I was not dissapointed in the least. It will run hard all day long without breaking a sweat. The sound quality isn't a world beater for sure but it sure made my hpms sound nice.
 
I use two of them for my home stereo in bridged mode with a pair of 79 cv ch504r speakers and not the best but i like them and at 250 per amp they rock
 
OK, old thread, but I have another 'Just scored one of these" story, and a question that is not specific to this amp.

I picked one of these up at a hamfest for $35. (Original no-suffix model with analog VU meters) The seller said it worked, but...

Well, it worked after it took me several hours to troubleshoot it and clean it up.

The original problem was no sound at all -- not even a pop or hiss at full volume. Skipping 2 hours of troubleshooting and searching for schematics... I found out that it was the protection relay. As they say in England, I "prised" the top off the relay, and there was a significant amount of visible, raised corrosion on the contacts.

About half a can of CRC contact cleaner later (a lot also went on each volume pot, which were very noisy/dirty), I had a working amp. (The house smelled better than usual, too.)

Other than the CRC Contact Cleaner, I only used a paper towel on the relay. I didn't scrape it with anything, and trust me, I used enough CRC so that there are no little fibers of paper towel in the relay.

But now I am not sure if I can trust it not to grow corrosion again. I am in humid Florida, and I only use the amp for an occasion volunteer DJ job.

So here is the question(s):

Can I trust this relay? Amp out of rack, Lid off of Amp, Cover off of the relay, trying to clean contacts with shirt tail -- is not something I want to be doing an hour after I was supposed to be set up for a gig.

What can I replace it with that might be better? There is enough room in there for a small power company switching station, so I am not too worried about mounting it.
 
Hopefully its a common type. Get the number off of it and try Mouser or Digikey. I have a pair of mono blocks I restored and I was able to find replacement relays, however it did include opening them up and swapping a wire in the relay. But I'm talking about a relay from 1971. Omron may make what you need. If you can get the brand and part number from the old one you should be able to find a data sheet. Then try to match one from Omron.
 
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