THX-Ultra Five-Channel Power Amplifier
amplifiers have received much attention over the years primarily because John
Curl has been a key designer of their flagship models. Mr. Curl's reputation in
the area of power amplifier design has been highly regarded in the audio industry.
One such design is Parasound's HCA-2205AT, which is a five channel THX-Ultra certified
amplifier. This multi-channel amplifier has the ability to drive difficult loads
while still providing enough current to easily meet the THX-Ultra requirements.
The signal path has no capacitors or inductors to degrade the sound. In addition,
the amplifier is designed to operate in a high-bias Class A/AB mode to minimize
crossover distortion. The massive toroid power transformer has independent secondary
windings for each channel. A total of 150,000 uF of capacitance is used to store
the large power reserves that supply the output transistors. The design uses hand
matched complementary JFET devices for the input stages, MOSFETs for the driver
stages and a total of forty beta-matched, 15 amp bipolar transistors on the output
stages. That's eight dedicated high-current bipolar transistors for each channel.
Heatsinks cover both sides of the unit and a good portion of the rear panel providing
completely conventional cooling without the need of a noisy fan. As a result,
the amplifier is capable of driving five channels with 220 Watts per channel into
8 ohms or five channels at 300 Watts per channel into 4 ohms. The front panel
indicators provide status including AC Present, Standby/Normal Operation,
Current Overload and Over Temperature conditions.|
The rear panel of the HCA-2205AT has the two additional handles that help distribute the weight during a move. The left side has five gold-plated unbalanced RCA connectors for each channel. In addition, level controls are provided for adjusting the sensitivity of each input independently. A THX reference mark is indicated for setting the proper THX reference level. There's also a 12 volt trigger input that we used with our Parasound AVC-2500u to remotely turn on the power amplifier. The center of the back panel is largely taken up by one of the three massive heat sinks. The right side of the rear panel holds the five pairs of speaker outputs on gold-plated 5-way binding posts. The detachable heavy gauge power cord plugs into the unit just below the speaker terminals.
One of our favorite 5.1 surround mixes is a track called Fire from the Studio Voodoo release. The aggressive African-style compilation features Swahili voices in various channels along with a gradual increase in volume and makes for a wonderful test track. In addition, when things get warmed up, a deep descending bass exercises the transition between the main speakers and the LFE (low frequency effects) channel. This artistic piece is highly recommended for 5.1 surround enthusiasts. Another interesting recording on DVD-Audio is the multi-channel 24/96 Brazilian Jazz disc in the MLP format. This high resolution, percussive mix is a real treat and certainly exercises the dynamics of your surround system. The sonic attributes of the HCA-2205AT were that of a high-end amplifier. The wide soundstage impressed us along with the pinpoint imaging between channels. The sound was neutral and free of harshness while still providing plenty of power to our speaker system.
Our M&K S-150THX main speakers
and SS-250 surrounds are not easy to drive for most amplifiers. In fact, with
our system a total of 33 individual drivers (15 in the three S-150's and 18 in
the pair of SS-250's) can be running at any given time and that's not including
the subwoofers. This requires a huge amount of power and the HCA-2205AT handled
it with ease. The amplifier never showed any signs of being strained, even at
very high levels. We have had this amplifier in our system for nearly six months
and it has performed flawlessly while still sounding wonderfully open and smooth.
Parasound AVC-2500U THX-Ultra DTS/DD Preamp/Processor
|Review at a glance|
Parasound HCA-2205AT Ultra THX Power Amplifier
Source: Manufacture loan
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