Parasound Halo A51 Amplifiers

Parasound Halo A51 Amplifiers 

DESCRIPTION

Halo A51 Five-Channel Amplifier

  • Power output: 250 watts RMS x 5 continuous, 20 Hz - 20 kHz at 8 ohms; 400 watts RMS x 5 continuous, 20 Hz - 20 kHz at 4 ohms
  • Current capacity: 60 amps peak per channel
  • Frequency response: 5 Hz - 100 kHz, +0/-3 dB at 1 watt
  • Total harmonic distortion: <0.2% at full power, <0.03% at typical listening levels
  • IM distortion: <0.04%
  • TIM: Unmeasureable
  • Signal-to-noise ratio: >112 dB, input shorted, IHF A-weighted; 102 dB, input shorted, unweighted
  • Dynamic headroom: >1.5 dB
  • Interchannel crosstalk: >78 dB at 1 kHz, >63 dB at 20 kHz
  • Input impedance: unbalanced 47 K ohm, balanced 94 K ohm
  • Input sensitivity (for 28.28 V output into 8 ohm): unbalanced 1 V, balanced 1 V per leg
  • Slew rate: >130 volts per microsecond
  • Damping factor: >1100 at 20 Hz
  • DC trigger requirements: +9 VDC to +12 VDC, 2 mA
  • Audio trigger requirements: 50 mV AC - 250 mV AC
  • Power consumption: standby, 25 watts; full power into 4 ohms, 3000 watts
  • Weight: 77 lbs.
  • Shipping weight: 92 lb.
  • Dimensions: 17.5" wide, 20" deep, 7" high (7.625" with feet)
  • Manufacturer''s limited warranty: 10 years parts, 5 years labor

  • USER REVIEWS

    Showing 1-2 of 2  
    [Dec 22, 2007]
    Harry_SF
    Audio Enthusiast

    Strength:

    Controlled bass, doesn't add color to the sound, lots of power in reserve, quality build.

    Weakness:

    Tight space for speaker cables in rear; tough to get big spades in. Also had a problem with ground loop hum (which my a/v tech told me was a problem he had noticed with a lot of Parasound amps he had installed). However, this problem was totally eliminated with a product called Hum X by Ebtech (another highly recommended product).

    I really didn't need to upgrade my amp (Outlaw Audio 7100, 7X100 watts), but I had a case of upgrade-itis and I wanted a more powerful amp for my planned purchase of bigger floor-standing speakers. Normally, I would buy the speakers first and then find the amp to match, but I didn't want to pass up a great price for a 6-mth old dealer demo. The speakers I ended up buying are very efficient (91db sensitivity), so I could have made do with the Outlaw, but I am still very happy I got the A51.

    Before I replaced my speakers, I hooked up the A51 to my existing Soliloquy monitors, which I thought was overkill, but, boy, was I surprised to hear a noticeable improvement in the Soliloquy's sound. I love the Soliloquys but they were too small for my new room after a recent remodel. They sounded way smaller and bass-shy when placed in the new room. When I hooked up the A51, the Soliloquys seemed to firm up, the sound, especially the bass, was tauter and the speakers just sounded more fluid. For me, the best indication of an improvement was when I put on Holly Cole's rendition of "I Can See Clearly Now," which has the double bass thumping in the background, as well as some solo piano riffs. This piece proved to my ears that the bass was definitely tighter and more defined with the A51 than with the Outlaw (which I really like and is a great value). As I was enjoying my music, I wife commented that the speakers sounded better -- and she has a very good ear. When I was reviewing cables, I used her to do double-blind tests and she kept picking the same one as the one she liked best.

    I haven't done the same review (Outlaw 100-watter vs the A51's 250) on my new speakers, but I'm happy to report that I love my new speakers (Focal BE 1027) and they have wowed everyone who has heard them. Two-channel music sounds close to live, and the movies at home feel just like the theater. After hearing the amp, in hindsight, I would have had no problems paying full price for it. Highly recommended!

    Similar Products Used:

    Outlaw Audio 7100, Audio Refinement Multi 5

    OVERALL
    RATING
    5
    VALUE
    RATING
    5
    [Sep 25, 2006]
    jwh2323
    AudioPhile

    Strength:

    See above.

    Weakness:

    It's big - I mean, what do you expect? This is not a weakness, of course, but the sucker will need air and the back has to come off of my synergy s40. However, in the rack with the door closed it works fine and I can hold my hand to it after Wagners "The Ring" or Gladiator and it's warm and toasty but not hot.

    I haven't written a review in awhile, but if there's any product that will bring a guy out of hiding it's the A51. If you're wondering, "Man, is that the 5 channel of my dreams...", well, it probably is. I told my wife, "This will be the last amp we ever buy." And after our demo she believesme. Perhaps a slight exaggeration, but you get a five year all in/TEN year parts warranty. I have my A51 hooked up to a pair of NHT T5 towers. I use two channels off the A51 for the B5 sub bases and two channels on the M5s, rightly or wrongly as the M5's are rated RMS below the Halo's 250. My system is two channel - downgraded for the wife two years ago and am going to stay low for awhile; but if the opportunity arises, sir, I'll be ready. Sound: the A51 is pitch dark, stunningly natural - takes my Music Hall MMf 5/Cambridge 640 pre to a ridiculous level - and shows, if you will, in all genres and with SACD, CD, DVD and LP absolute power and absolute finess. Total channel separation and absolutely - yes, I give the term great levity - solid stereo imaging: tall, wide and deep. I am using a NAD c372 for a preamp, bipassing the amp section, for now, with a Marantz SA8260, and the supplied X1 crossover with the NHTs. Wire: Audioquest T8 for the M5s, Audioquest Bedrock for the B5s. When my wife and I sat down and started spinning wax - we could not believe our ears. She's an Alias addict, so when we hit the first season dvd set she wouldn't stop smiling. Two channel stereo image was wide, unflinching, and to the NHTs credit, totally smooth from hi to low. When I played the two for the road cd/bela fleck, Edgar's double bass was powerfully rendered, air all around, and in terms of resolution it rivaled sacd. Peaks, sticato, it's all amazing. Did I mention the peaks? Everyone who sits with us and watches a dvd comments that the two channel set up we have blows their surround sound away - ah, stereo. I cannot stop listening to my stuff and the best complement I can give this thing is that I have been upgrading since 2000 and this is the first time I have ever sat down and thought, "Well, we're done." I never think of new wire or hardware to buy, only music. Wish I had time, I'd write on this amp for a week. Add up the bucks you'll drop on receivers and upgrades in the next five years and see if you shouldn't just save time and, in the long run, money and scoop this thing up. When I read Tellig's review of the JC 1 monoblocks, I just hear him talking about the a51. It's an unbelievealbe work of art. See the website. I used RCAs.

    Similar Products Used:

    Denon AVR 2803 - similar, no, yet I list it
    Harmon AVR 520 - bless its little heart!
    Rotel RB981
    Soundcraftsmen
    Carver

    Save up, folks, and just get one. You'll never look back. Look at that list there and add up the costs and I'm staring a second one in the face. Take my father's advice: get the component you want, wait until you can afford it, and then use it for fifteen years. You'll be spending all that time on the .coms and ebay reading great works of literature or stereophile or sleeping to nacht music.

    OVERALL
    RATING
    5
    VALUE
    RATING
    5
    Showing 1-2 of 2  

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