Product Review (August 2002) - Parasound HCA-2205AT
THX-Ultra Five-Channel Power Amplifier
Parasound 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.

Construction
Conventional linear amplifiers have always been somewhat judged by their weight. After all, linear high current designs require large power transformers for continuous power needs as well as large capacitors to hold huge power reserves for peak transients. In addition, when you add five channels to the unit, you're talking about some serious weight. As expected, the HCA-2205AT is a back-breaker at a hefty 85 pounds. The build quality of the amplifier is impressive and far better than many amplifiers we've seen in this class. Given a list price of less than $2000, we were surprised to see this level of build quality. Handles located on both the front and back are essential when moving the unit around. The front panel is made from a hefty chunk of aluminum and large heat sinks occupy most of the outer perimeter of this well made chassis.

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.

Setup
The Parasound AVC-2500u was used to drive the HCA-2205AT amplifier. Six UltraLink Platinum Ultima Mk II cables provided the link to the amplifier. The HCA-2205AT drove our three M&K THX-Ultra certified S-150THX front channel speakers and two rear SS-250 Tripole® surrounds. A pair of M&K MX-350 MkII THX-Ultra subwoofers was used to handle the low-end with their built-in 350 Watt amplifiers. All main and surround speakers are rated at 4 ohms and require a substantial amount of current to drive them at high levels. The huge 2kVA toroid power transformer, large filter capacitors, and 8 output transistors per channel are the main reason why this amplifier had no problem pushing large amounts of current into these low impedance loads.

Performance
We tried a variety of source material with this amplifier including our high resolution multi-channel SACDs and DVD-Audio discs. There are also plenty of high-impact movies with Dolby Digital and DTS 5.1 audio. Our system is currently using a THX processor and an M&K BMC mini 5.1 bass management unit for the analog 5.1 inputs, so the main speakers have a crossover frequency set at 80 Hertz. Therefore, the amplifier was spared the task of driving our main speakers below this frequency.

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.
- Kevin Nakano

Review System

Preamplifier/Processor: Parasound AVC-2500U THX-Ultra DTS/DD Preamp/Processor
Front Speakers: Miller & Kreisel S-150THX (L+R) and S-150AC (Center) Speakers
Rear Speakers: Miller & Kreisel SS-250 Tripole® Surround Speakers
Subwoofer: Two Miller & Kreisel MX-350THX MkII THX-Ultra Push-pull Subwoofers
Room Treatments: Echo Buster panels and Bass Buster towers
Display: Pioneer Elite PRO-610HD 58-inch HD-Ready TV (ISF calibrated)
Scaler: Focus Enhancements CenterStage2
Set-top Box: RCA DTC100 HDTV/DSS Satellite Receiver
DVD/CD/SACD Player: Sony DVP-NS900V DVD/CD/SACD Player
DVD Audio/Video Player - Kenwood Sovereign DV-5900M 400-Disc DVD Changer
Laserdisc Player : Pioneer Elite CLD-99 and CLD-D704 Laserdisc Players
D-VHS VCR: JVC HM-DH30000U D-VHS High-Definition D-Theater VCR
A/V Cables: Ultralink Platinum and Advanced Performance Series Cables
Audio Analyzer: Sencore SP295 Audio Analyzer
Video Generator: Sencore VP300 SDTV/HDTV Video Pattern Generator
Color Analyzer: Sencore CP288 ISF Certified Color Analyzer

Review at a glance
Parasound HCA-2205AT Ultra THX Power Amplifier

Features

  • Circuitry designed by John Curl
  • Lucasfilm Home THX Ultra-certified
  • Direct Coupled - no capacitors or inductors in signal path
  • DC Servo and relay protection circuits
  • High bias Class A/AB operation
  • 2 kVA Toroid power transformer with independent secondary windings for each channel
  • 150,000 µF power supply filter capacitance
  • Independent power supplies for each channel
  • Hand matched complementary JFET input stages and MOSFET driver stages
  • 40 beta-matched 15 amp, 60 MHz bipolar output transistors
  • AC present, standby/normal, current overload, temperature indicators
  • Rear mounted gain controls and rear handles
  • 12 volt DC automatic turn-on circuitry
  • Tiffany-style RCA input jacks
  • Gold-plated 5 way speaker binding posts
  • Color coded, gold plated brass banana plugs included
  • 4 rack space height front panel

    Specifications

  • 220 watts RMS x 5, 20 Hz - 20 kHz, 8 ohms, all channels driven
  • 300 watts RMS x 5, 20 Hz - 20 kHz, 4 ohms, all channels driven
  • Current Capacity: 60 amperes peak per channel
  • Slew Rate: 130 V/µsecond
  • Power Bandwith: 5 Hz - 100 kHz, +0/-3 dB at 1 watt
  • Total Harmonic Distortion: < 0.03 % at full power
  • IM Distortion: < 0.03 %
  • TIM: unmeasurable
  • Dynamic Headroom: > 1.5 dB
  • Interchannel Crosstalk: > 80 dB at 1 kHz; > 60 dB at 20 kHz
  • Input Sensitivity: 1 V for 28.28 V, THX Reference Level; 1.5 V for full output
  • Input Impedance: 33 k ohms
  • S/N Ratio: > 118 dB, full power; > 96 dB, THX Reference
  • Level Damping Factor: > 1000 at 20 Hz
  • Power Consumption: 1500 watts

    Company Information
    Parasound Products, Inc.
    950 Battery Street
    San Francisco, CA 94111
    Ph: 415-397-7100
    Fax: 415-397-0144

    Source: Manufacture loan
    MSRP: $1999
    Size: w 19" x h 7" x d 19 1/2", h 7 5/8" with feet (WxHxD)
    Weight: 85 pounds
    Warranty: 10 years parts and 5 years labor
    URL: www.parasound.com

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