Parasound HALO A 21 Amplifier Review
Reviewer: Shane Mattson
Review Period: 10/20/05-->11/30/05
Product Description:
250w/ch 2 channel amplifier
A 21 Features:
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Circuitry designed by
legendary John Curl |
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THX Ultra 2 certified |
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High bias Class A/AB
operation |
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Balanced inputs with
discrete circuits and XLR connectors |
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Direct Coupled - no
capacitors or inductors in signal path |
| |
Complementary MOSFET driver
stage and JFET input stage |
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16 beta-matched 15 amp, 60
MHz bipolar output transistors |
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1.2 kVA encapsulated toroid
power transformer with |
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independent secondary
windings for each channel |
|
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100,000 µF power supply filter capacitance |
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DC Servo and relay
protection circuits |
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AC present, channel status,
high temperature indicators |
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Gold-plated RCA input jacks,
loop output jacks |
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Heavy-duty 24k gold-plated
5-way speaker binding posts |
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Auto turn-on by 12v trigger
or audio signal, 12v trigger out |
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Rear panel gain controls;
ground lift switch |
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4u Chassis; carry handles;
rack mounting adapter included |
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Parasound’s 10 years
parts, 5 years labor warranty |
A
21 Specifications:
| |
Continuous power output: |
|
 |
250 watts RMS x 2, 20 Hz - 20 kHz, 8 W,
both channels driven |
|
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400 watts RMS x 2, 20 Hz - 20 kHz, 4 W,
both channels driven |
|
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750 watts RMS x 1, 20 Hz - 20 kHz, 8 W
|
| |
Current capacity: 60 amperes peak
per channel |
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Power bandwidth: 5 Hz - 100 kHz,
+0/-3 dB at 1 watt |
| |
Total harmonic distortion: <
0.2 % at full power |
| |
IM distortion: < 0.04 % |
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Slew rate: >130 V/µsecond |
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Dynamic headroom: > 1.5 dB |
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Interchannel crosstalk: > 80
dB at 1 kHz; > 63 dB at 20 kHz |
| |
Input sensitivity: 1 V for 28.28
V, THX Reference Level |
| |
Input impedance: 33 k W
unbalanced; 66 k W
balanced |
| |
S/N ratio: > 112 dB, input
shorted, IHF A-weighted |
| |
Damping factor: > 1100 at 20
Hz |
| |
Voltage: 110V – 120V |
| |
Dimensions: 17-1/4" w x
7-5/8" h x 19-1/8" d, 7" h without feet |
| |
Net weight: 60 lbs. |
About Parasound:
Everything you
want to know about the company can be found here.
Evaluation
System
Meridian 565Z3
(Software version 6.2a) Surround Processor/Preamplifier
Denon DVD-2900 Universal Player used as an audio transport
Mirage M3-si Loudspeakers
Bi-wire run of TMC Gold Reference speaker cables
PS Audio Xtreme Statement single-ended Interconnects between 565 and A 21
Wireworld Gold Starlight 5 digital coax interconnect between 2900 and 565Z3.
Source components are plugged into a PS Audio Ultimate Outlet.
Element Cable power cord & 20 amp high current PS Audio Ultimate Outlet used with the
A 21 during the review.
Build quality, first impression:
I could tell by the less than enthusiastic
expression on the delivery man's face as he carried the mammoth box up my driveway that
this was going to be a fun product to install. Parasound ships the A 21 in two
boxes, one extremely large outer box with a smaller more lightweight inner box that
contains the amplifier. As I peeled open the layers of cardboard I started to
salivate...yes, I always get this way when opening up a box containing a new piece of
equipment. There it was, this massive piece of audio jewelry waiting to be unpacked,
plugged-in and put into service. Thankfully, there are two carrying handles on the
back of the amplifier which made transporting much easier then I had anticipated.
After hauling the amplifier to its resting place behind the right channel M3-si
loudspeaker I connected the speaker cables, interconnects and power cable. The back
panel consists of balanced and single-ended connections, low-level signal-ended
pass-through for connection to another amplifier/subwoofer, channel gain controls
(normally set to max), DC trigger in/out for remote power-on/off, ground lift toggle
switch, bridging switch and speaker binding posts.
The A 21's build
quality is outstanding. The new look of the Halo line is extremely refreshing
compared to the fairly sterile look of older Parasound products. A soft blue light
glows behind the power button and the "P" logo on the front panel dimly glows
red when the unit is connected to AC. When the amplifier is powered on (by pressing
the power button), the soft blue light behind the power button intensifies as does the red
light behind the logo. The left and right channel status indicators also glow blue
indicating no detected faults. It's hard not to judge a component by its appearance
in the world of high-end audio and the new HALO line truly holds its own against the
sexiest amplifier designs currently on the market. The A 21 looks like a parked
Aston Martin DB7...more on this later.
Performance,
first impression:
I asked the Founder/CEO of Parasound, Richard Schram if there
is a recommended burn-in period for the A 21. Mr. Schram recommended approximately
100 hours to obtain the lowest* level of detail the A 21 is capable of producing.
Based on Mr. Schram's recommendation, my approach to this review was to listen to the
amplifier right out of the box (had to...could not wait 100 hours!!) to obtain a first
impression and then begin the grueling burn-in process by playing satellite radio
continuously for several days until approximately 100 hours had elapsed.
Out of the box the A 21 sounds wonderful. I sampled
several Red Book CD's of different recording quality and musical genera's and quickly came
to the realization that the A 21 was indeed a very special amplifier, and could not wait to begin the serious evaluation after burn-in.
Having owned a few Mark Levinson amplifiers in the past including the No.27 and No.332,
I've become quite familiar with the sonic characteristics of low level detail and
transparency. Did the A 21 convey those same sonic characteristics? Not
quite.....however let's burn the amplifier in for 100 hours before passing any critical
judgment.
*By 'lowest' I'm referring to the amplifier's
ability to dig out every ounce of low-level detail from a recording.
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