Recently I picked up a couple of these workhorses for $169.00! They list for about $459.00.

I have used this model in my hobbyist multitrack studio for several years now and it has held up quite well. I am powering a pair of Behringer 2031P's with it. Since they are a 4 ohm speaker, I chose the Alesis RA500 for the price per watt value. Initially there were issues with one channel failing, due to a relay not coupling, but after time, it "healed" itself. I did get good service from my local Alesis dealer who kept an amp in stock in case I needed a back up.
It is a very quiet amp and I have driven 4 ohm speakers with no trouble. It is very stylish and looks very nice in a rack with the LED output display on the front.

Details of the product can be found at: http://alesis.com/ra500

Alesis also offers the RA100 and the RA300.

Specs from manual:

Size 18.9" W x 5.63" H x 10.71" D
(480mm x 143 mm x 272 mm)
Rack units 3 RU height
Weight 28.5lbs = 13.0Kg
Rated output, per channel
4 ohms @ 1kHz, .02% THD+N 250 watts RMS per channel
8 ohms @ 1kHz, .05% THD+N 150 watts RMS per channel
8 ohms, bridged mono mode 500 watts RMS
Signal to Noise Ratio 105dB, 22Hz-22kHz bandwidth referenced to rated output
Frequency Response 10Hz – 70kHz +0, -3dB
Damping Factor 200
Slew Rate 60 V/µs (two channel), 120 V/µs (bridged mono)
Input Sensitivity +4dBu (1.23 V) for rated output with input control at maximum
Maximum input level +26 dBu
Input impedance 20k O, balanced, 10 kO unbalanced
Crosstalk -85dB, 1kHz
All measurements done over a 20Hz-22,000Hz range with 1KHz sine wave at Full Scale, except for the dynamic range which was done with a -60dBFS 1KHz sine wave.

Comparable products include Behringer's Reference Amplifier A500, which is a 2 rack space whereas the Alesis is a 3 rack space. While the Behringer is a comparable in specs, it is not as hefty as the Alesis.

A good preamp is a necessity to any good sounding system. This amp will only "repeat" what is put into it.

I would recommend this amp for anyone whether or not they are looking for a quite pro amp(no fan) or not.
I have purchased these to bi-wire/bi-amp a pair of Infinity Kappa 7.1 Series II. Plenty of power to keep them safe from distortion.

Good overal frequency responce
250 watt/4 Ohm more then you wan't to use on a nearfield monitor (lot of headroom!)
Balanced XLR input for long lines when the amp is in a remote area
Jack and RCA input connectors
NO FAN NOISE, no noise at all....
Good looks

It's heavy with +/- 13 Kg (if you wan't to use it for recording sessions on location)
Speaker clamps could have been bigger, if the amp is in a remote area, you wan't to use big diameter speaker cable, for short distance 4 mm will do fine!

This amp is worth every €/$! I was looking for a quiet amp to drive my Dynaudio BM6 monitors, and the RA 300 of Alesis was my first choice. As it was not in stock, I decided to purchase the RA 500. More then enough power to drive the
BM6 at a good mixing level. The sound is natural, no over exporure in any frequency, and the bottom end is amazing! It gives me a tight sub and bass, normaly provided by amps with a far higher damping factor!

Similar Products Used:

Alesis RA100
Samson Servo 260

Wide frequency response and excellent midrange and highs. Quiet given the target market for this amp.

Bass is not as solid or tight as with many Crown power amps, but for the money, it's quite good.

Got a new, factory sealed RA500 on eBay for $250 plus shipping. Couldn't pass it up. It's currently connected to a nice tube preamp and frankly I can't quite believe how good it sounds. Mid and highs are sweet and transparent. Bass is better than I thought it would be given the low damping factor.

Similar Products Used:

AMC 2100, Crown D-150A, Crown DC-300A, NADY 2250 power amps

Clear and transparent and sounds good across all frequencies and across a wide volume range. No fan (big heatsink) so silent operation is granted for such a powerful Amp. The price of £189 was very good value for money too.

None from an audio point of view. Just the annoying 3 Amp fuse blowing.

Great looks and the LED display is useful showing power output to each chanel. Construction appears to be rugged. I would question the suitability of the packaging for such a heavy Amplifier and strongly suggest an inspection of the unit in the shop if you can. I am on my second unit as the first one kept blowing fuses when switched on. The unit is fitted with a 3amp fuse in the moulded plug and this is the one which repeatedly blew over the first two weeks of ownership. The second unit has been in occasional use for the past week and so far has only blown one which was earlier today. I am concerned that there may be a short circuit which makes contact or arcs within the Amp when cold. I have not had a fuse blow when the Amp is at normal working temperature. The sound is extremely clear with a transparency hich is undeniably aeal bonus. The build quality appears to be solid. With the exception of the fuse issue I would not hesitste to recommend this Amp. I do not want to return it as a replacement which sounds as good will cost a lot more than I have paid. Alesis may need to consider what might be causing the 3 Amp fuses to blow though.

Very quiet and well balanced. Good highs lows and clean mids. Great price$$$. Cool design very streamlined.

Only a one year warranty and I've heard horror stories about getting Alesis products serviced (obsolete parts and the like). But like I said if your on a budget it's a good amp.

I just got this so my review is based souly as a new purchase. I have yet to find a review on these so I thought I'd post one just to give a rough idea from what I've heard so far. This is a great amp for the price very even, nothing stands out so far and I can't hear any kind of noise as of yet. Considering it is about half the price of any of it's competitors in the same category (power, frequency, etc.) I think it holds up pretty well. If you are on a budget and looking for an inexpensive yet good sounding amp I would recomend this. Specs are as follows Size 18.9"W x 5.63"H x 10.71"D Rack units 3 RU height Weight 28.5lbs = 13.0 kg Rated output per channel 4 ohms @ 1kHz .02% THD+N 250 watts x 2 8 ohms @ 1kHz .05% THD+N 150 watts x 2 8 ohms, bridged mono mode 500 watts RMS Signal to noise ratio 105dB,22Hz-22kHz bandwidth referenced to rated output Frequency responce 10Hz-70kHz+0,-3dB Damping Factor 200 Input sensitivity +4dBu(1.23V) for rated output with input control at maximum. Maximum input level +26 dBu. Crosstalk -85dB, 1kHz