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Editors' Choice Award Winner 2013 - The Absolute Sound Magazine
"Best Solid-State Amplifier" 2008/2009 - The Absolute Sound Magazine
250-Watt THX Ultra II Amp Hits a 'Home Run'
Parasound's Halo A21 two-channel power amplifier has the brute force you need for ultra-realistic musical reproduction and hair-raising movie soundtracks. Its raw power is matched by elegant circuit design from audio guru John Curl in collaboration with CTC Builders.
"Highly Suitable for Driving Anything"
The Absolute Sound magazine rated the Halo A21 as the "Best Solid-State Amplifier" in the Winter 08 / Spring 09 issue, praising it as "highly suitable for driving anything from power-hungry planars like Maggies to low-sensitivity acoustic suspension cones."
The A21 is the two-channel version of Parasound's benchmark A51 five-channel amp, which the May 2003 issue of DVD Etc. magazine said hit the "proverbial home run." Matched JFET inputs, MOSFET drivers, and high-current bipolar outputs contribute to its exceptional performance.
"Close Enough to the Very Best"
The Absolute Sound magazine awarded the Halo A21 its "Editors' Choice" recommendation for 2012. "Though not the last word in solid-state amplification, the A21 comes close enough to the very best, at such an affordable price…"
"Its luxurious appearance is more than skin deep. Parasound’s A21 dispensed truly sumptuous sound," notes England's Hi-Fi News magazine for November 2011. "Demonstrating the control and grip of the Bryston and Anthem but with the velvety midband richness of the ATC, the Parasound’s ability to resolve detail, while remaining composed and easy on the ear, proved the equal of my ‘reference’ Levinson amplifier."
Balanced Inputs and Discrete Circuits
The A21 boasts balanced inputs with discrete circuits and XLR connectors. Beautifully implemented high-bias Class A / AB operation makes the most of an impressive 250-watt-per-channel power output at 8 ohms and 400-watts-per-channel at 4 ohms. The 1.2 kVA encapsulated toroidal power transformer with independent secondary windings for each channel and 100,000 µF power supply filter capacitance delivers an impressive current capacity of 60 amps per channel. The direct-coupled design uses no capacitors or inductors in signal path. The complementary MOSFET driver stage relies on the firepower of 16 beta-matched 15 amp, 60 MHz bipolar output transistors and works in combination with a JFET input stage.
'Instant Warm-up' Feature
Like all the other amps in the Halo product series, the A21 has Parasound's exclusive bias circuit, which permits the amplifier to sound perfect from the instant it's turned on, rather than having to wait for bias to gradually build up as the amp warms up over time. Very high bias allows greater Class operating range than others. Even Halo's implementation of its automatic turn-on feature is exceptional. Special relays bypass the AC "soft start" circuitry after it's done its job for the purest AC and the purest sound.
And That's Not All…
AC present, channel status, and high temperature indicators team up with DC Servo and relay protection circuits to keep this powerhouse running safely at peak performance for years of reliable service. Auto turn-on by 12-volt trigger or audio signal simplifies home theater and multi-room operation. Other features include heavy-duty 24k gold-plated five-way speaker terminals, gold-plated RCA input jacks, and a rear-panel ground lift switch.
Editors' Choice Award Winner 2013 - The Absolute Sound Magazine
"Though not the last word in solid-state amplification, the A21 comes close enough to the very best, at such an affordable price."
"Its luxurious appearance is more than skin deep. Parasound’s A21 dispensed truly sumptuous sound from Maxwell’s ‘Everwanting…’ with oodles of bass grunt and tight precision. The singer’s soulful multi-tracked vocal lines were depicted exquisitely within the track’s myriad percussion details. Demonstrating the control and grip of the Bryston and Anthem but with the velvety midband richness of the ATC, the Parasound’s ability to resolve detail, while remaining composed and easy on the ear, proved the equal of my ‘reference’ Levinson amplifier."
- Hi-Fi News magazine, November 2011
Audio Advisor - Parasound Halo A 21 Power Amp - Overview
Audio Advisor - Inside the Parasound Halo A 21 Power Amp
Audio Advisor - Parasound Halo A 21 Power Amp - Rear Panel
Audio Advisor Insight - Parasound High Value to Price Ratio
Audio Advisor Insight - Parasound in Hollywood
Audio Advisor Insight - Parasound Customer Service
Audio Advisor Insight - Parasound Amplifier Power
|Product Reviews Click here to review this item|
|First impressions- Parasound Halo A21|
The amplifier arrived in a huge box made extra heavy duty with plastic straps and handles built into the sides. Inside that box was another box which housed the A21. Large pieces of styrofoam held the amp away from any contact with the exterior box. I wanted to describe the packaging to remove any concerns about your A21 arriving safely. Making the connections was pretty straight forward on the A21. I noticed Parasound included 2 wires for 9v to 12v DC triggering the amplifier on/off via your preamp/surround reciever. One was the smaller sub mini 2.5 mm wire which has the male 2.5mm connector on both ends. The A21 uses the 2.5mm for its trigger input. The other wire included has a male 2.5mm connector on one end and a slightly larger male connector on the other end which is what my setup required. I planned on using the auto on/off feature on the A21 which turns the amp on when an audio signal is present and turns the amp off within five minutes of no audio signal- unfortunately that didnt happen. The auto on/off has a nob to adjust the sensitivity but when the volume was not up fairly loud the A21 would shut off like it wasnt receiving a audio signal. This occured even with the sensitivity on maximum. The issue was solved by using the 12v trigger on/off with the extra connection wire Parasound included mentioned earlier. I prefer the quick on/off the 12v trigger provides over the auto on/off triggered by a audio signal or lack of one. *That was the only issue ,if you can even really consider it one, as far as set up. Performance- I was impressed with how quiet the A21 is even at high volumes. When the music pauses during changes in a song or when certain instruments are being played gently I hear no background noise at all. In between tracks it is completely silent. Not even the slightest hiss. This amp provides plenty of power, punch, and headroom for even the most demanding music/changes therefore improving sound quality as well. Even at lower volumes this amp sounds fantastic. At this point I have only had the A21 Halo hooked up for a couple days but already I am very impressed. Perhaps in 30-60 days I can give an updated review and go into more detail on the Parasound A21 Halo amplifier.
|- Linda R, FL|
|Obvious power, authority, control, speed, punch, slam, and refinement|
Hello, My wife and I listened to the Parasound A21 power amplifier along with the Parasound JC-2 preamplifier with the Usher Be-10s last weekend March 7th, 2009 with MIT speaker cables and interconnects. Sadly, the system only had a Rotel CD player for its source, so it was limited by that. However, this amplifier made it instantly clear that it has massive power to tap into at any moment and for long periods of time. It sounds as easy on the ears at very soft listening levels as it does when cranked up and then some. The abundant authority, control, punch, slam, speed, timing, pace, and drive were just downright visceral and intense. The bass tightness and impact were outstanding as well as offering terrific pitch definition and tracking of a bass line with the percussion without cluttering them together. The midbass was strong and tight too, yet musical and not overbearing one bit; just as the bass can be described. The midrange and treble were fluid, flowed like good red wine at an Italian dinner, and lavished our ears with sensuous saxophones, open and sonorous strings of plucked guitars, the epitome of intimate allure as the jazz singers wove their spells of song as if slinking around right in front of us with every breath and gasp for the next one rendered so realistically it was beguiling. The presence of the component was an asset to this system and listening experience as it allowed, and made, the speakers come to life with a palpable bloom and airiness that let our song by John Denver warm our hearts like never before due to how lifelike it sounded. This amplifier offers depth of soundstage and solidity to the foundation of bass that is exemplary and easily equal to other components many times its modest cost. We were thoroughly impressed and would gladly invest in one, or two, of these without any doubt at all. Richard Schram of Parasound told me in an Email from last summer that the A21 will offer about 15 to 20 wpc in full, legitimate class A mode when bridged mono. The class A high biasing comes through in stereo mode, as we listened to it, for about 7.5 wpc, and makes this amplifier very smooth and easy to listen to with no harshness or listener fatigue at all. It is extremely neutral and does not muffle, veil, dull, or slow down the sound at all. It breathes performance into your system so that you can enjoy your favorite music so easily. This system, with this Parasound A21 in it, is one of the most emotionally engaging systems that I, and now we, have ever heard; be it solid state, tube, or both, and regardless of cost or brands included. That says a lot for those who really know about and have heard what is out there to audition. I have auditioned 130 brands and sold 78 brands in addition to those, so I have a pretty good idea of this stuff, along with doing it since I was 16 and am now age 40, so theres two dozen years of experience to hopefully lend credibility to this personal review. The amplifier is also very visually appealing in general appearance, fit and finish first rate, and my WAF Wife Acceptance Factor is 100% positive. There are no perceivable flaws or shortcomings of any kind. You would have to, and I do mean have to, invest much more money to get noticeably better sound. We are planning on getting two of them and running them in a vertically bi-amplified manner at first or bridging them and having fun with that sheer power. Keep in mind that Mr. John Curl, formerly of Mark Levinson, is the designer of this product. That in itself says a great deal about the technical competency that this amplifier was conceived with. Bravo for a job very well done !! Sincerely, Tom & Erin near Allentown, PA.
|- Tom F, PA|