Small, sound good for the price, $100.

Fans get annoying after a while.

I have had 2 of these amps for a while and they run a system with 2 speakers that dont need much power, they sound pretty good considering they aren't that great of speakers. I just purchased some MMG's I am going to see if I can get them to run them (this will be fun), if it works good, I'll check back in later. I give the 5.1's a value rating of 5 because you can't beat the price for what you get, and overall rating of 4 because I think there could have been atleast 1 more feature to them.

Balanced/unbalanced inputs, "daisy-chain" capable, detachable power cord, high current, mono-block design, gain control, phase control, price, indicator lights (signal presence, protection, and peak), low-cut, headphone out-put (for one channel like an airplane style), and 5-way binding posts (hurray for spades).

Noisy cooling fan (noticible during quiet passage), slight hum for the first 30 minutes of operation, lacks a low-pass filter, lacks auto-on, and most likely a small power storage capacitor.

This is maybe the one of the most effective cheap tweeks you can do for your HT system if you have a center channel pre-out. This amp is usually on sale at Spidergear.com for less a $100 before shipping (get someone like JandR to price match since at least they answer your Emails). I bought this used on the marketplace at this particular site for the intention of using this for a passive car sub for HT. Unfortunately the peak light keeps lighting up during action packed scenes at theater reference levels though you wouldn't notice this as the sub never distorted.

The main thing I use it for currently is the Center channel of my HT which is far superior to amp in my Denon 2400 (this is a very good AVR but still it's trying to compete with a pure amp). The separation and detail of this amp is phenomenal and definately took the center channel to a higher performance level (Optimus CS5). I advise anyone who uses an AVR with a good center pre-out (the lower end pioneer I had couldn't do this) to use this only if you have a setup to put this in an enclosed area as the fan is noticible during quiet passages and the fan is on constantly from start to finish. Mono-blocks are definately the way to go.

Some concerns, this thing lacks an auto-on switch and draws enough power using a 3-prong outlet that you can't use an accessory outlet of your AVR to switch it on or off. This also lacks a 12v trigger as well though it has a front rocker switch toggle to turn on/off with. This thing is also setup where you can "daisy-chain" the power cord (not a conventional type socket just like what is on the computer) but I don't know if you can turn on/off all the amps hooked-up in a series with one flick of the switch (instruction book or the web site doesn't state this). The cut-off switch for the high pass doesn't indicate whether the cut-off is in the depressed or out position (sorry can't remember off hand one way or the other). The amp also produces a slight hum for the first 30 minutes then after that there's no problems (I think this might have more to do with a flourescent light being on the same circuit).

How does this compare to the other amps listed above? First of all I would rather own two of these over just the Amp-1a as these seem to more power in the two-channel setup and are far more flexible for most usages. The Adcom is far brighter though it does possess more control in the bass department but it lacks the resolution of details these mono-block possess (in fact it was demoted to driving the passive sub). Though the Denon is a good AVR it doesn't compare to the sheer performance of an amp that only has to do one duty and one duty only (neither does a friends Denon AVR95 or another friends Yamaha 1105). This definately a good product if used for the purpose of driving one-channel though I would consider the 5.3 if you want to drive a sub. I just wish this had a low pass filter as well as this also pushed the slight leak that the Denon, a friends Yamaha, and my Technics decoder allow to bleed thru their respective sub-outs.

I will give this a 5 for value since it is the cheapest new high current amp availible (wait til hopefully Outlawaudio try something like this). I will knock down a speaker for the continous running fan, and another speaker for not having a low-pass filter as most people will most likely try this out for a sub (which was my original reason for purchasing this). This does make it where I will definately buy a pair of their 5.3 for my future system.

Similar Products Used:

AudioSource Amp-1a, Adcom 535 (Nelson Pass design), and a channel on the Denon 2400.

Detachable power cord, ability to daisy chain. Stable to 2 ohm loads.

The High Pass filter is reall a waste of time as is the phase button. Noisy continuosly running fan.

I bought this amp to power a sub for my computer room sound system. In that regard it does a really good job.

I compared its sound quality against a Marantz MA500 and a Mackie 1400i . I actually preferred the sound of the AMP 5.1 over the other two in terms of sound quality, with the MA500 a close second followed by the Mackie.

The comparisions were made using a DIY sub with 2 different drivers tested in the same enclosure. One of the sub drivers was a car audio Soundstream USA12 DVC which had 4 ohm voice coils wired in parallel. The AMP 5.1 never even hiccuped with the 2 ohm load! Pretty impressive for a 100.00 amp! The MA500 would play it but not very loudly before shutting down, of course the mackie had no problems with the 2 ohm load either.

I only gave a 3 star rating for overall for 2 reasons, the continuos fan that does get annoying, and the useless high pass filter that should have been a low pass! Come on Audiosource... you could have sold a lot more of these amps with a fixed 80hz or adjustable low pass filter!!!!

Similar Products Used:

Marantz MA500

Got the Amp 5.1 monoblock at J&R Music World for $149.00. It delivers 100 watts into a 4 ohm load and the maufacturer claims stability into 2 ohm loads. Audiosource also makes the similar Amp 5.2 (150 watts/4 oms) and Amp 5.3 (250 watts/4 ohms). The Amp Five series monoblocks are perfect for driving a passive subwoofer, multichannel use or whole house distribution of music. You just buy the number of monoblocks you need.
Audiosource also sells a chassis that will hold a number of monoblocks in various configurations. The Amp 5.1, like its siblings comes in a solid, ribbed metal case which at 2 3/4" wide x 5 1/2" high x 11 3/4" deep, approximates the size of a Webster's dictionary. Its listed weight of 7 1/2 lbs. feels much heavier in one's hand.

Features include balanced and unbalanced inputs, very good quality gold 5-way output binding posts, detachable power cord, phase button that selects zero or 180 degrees out of phase, low cut button, cooling fan (the tiniest cooling fan I've ever seen -- looks like it belongs on a PC board), signal, protection and peak output LEDs, etc., etc. The input and power connections are daisy-chainable.

Inside, there is a surprisingly large toroidal power transformer, which together with the metal case, accounts for most of the unit's weight. There are what appear to be two output transistors bolted directly to the metal case, the entire surface of which acts as the unit's heatsink. The unit's low cut button cuts the low bass for small speakers which can't handle low bass or in cases where a separate powered subwoofer is used and you don't want the Amp 5.1 to reproduce low bass, such as if driving a satellite. A much better or additional feature would have been a high pass cutout that would have let through only low bass. My surround preamp, the Harman Kardon PT-2500 passes only a full range signal from its subwoofer outputs. It would have been nice to be able to cut out everything above low bass at the input of the Amp 5.1. Another feature that would have been useful is automatic turn on of the unit when an input signal is sensed.

This monoblock compared favorably in output level and bass potency to one channel (80 watts) of my Harman Kardon PA-5800 home theater amp. That primarily how I evaluated it because I bought it strictly for subwoofer use. It runs pretty cool and I was not able to get the tiny cooling fan to come on at any time. Overall, not bad for such a compact and inexpensive unit. I give the AMP 5.1 three stars for quality and value, which in my book is still a quite good score. The inclusion of automatic power on with an input signal and a high cut filter would have earned it four stars.

great price..129 at j and r music world

can hear slight fan noise, but no big deal

for 129 dollars you cant beat it. sounds great, much more powerful that 100 watts would seem. very satisfied

Similar Products Used:

amp3, audiosource

Cooling fan runs continuous. There is not an auto on feature to turn amp on when a signal is received.

Hook up was very easy. It works just fine for my center channel in my home theatre setup. I wish this amp had an auto-on feature. Never runs hot or overloads when playing movies at high volume levels.

This seems to be a very good deal for the $99 + shipping I spent at Spidergear.com. You can't go wrong if you need the 70 watts at the 8 ohm rating.

Someone should buy this if you're center channel amp is having problems in you're H/T receiver like mine !

Similar Products Used:

Kenwood amp , not sure what model.