Parasound

John Curl brings his art to home theater with this award-winning amplifier. With over 1200 total watts on 6 channels, this is one of the most powerful and popular THX-certified amplifiers in the world.

SPECIFICATIONS

Continuous Power Output
  > 135 watts RMS x 6, 20 Hz - 20 kHz, 8 Ω, all channels driven
  > 200 watts RMS x 6, 20 Hz - 20 kHz, 4 Ω, all channels driven
Continuous Power Output - Bridged
  > 350 watts RMS, 20 Hz - 20 kHz, 8 Ω, each bridged channel, 3+4, 5+6
Current Capacity:
   30 amperes peak, per channel
Slew Rate:
   > 130 V/盜econd
Frequency Response:
   12 Hz - 120 kHz, +0/-3 dB
Total Harmonic Distortion
  < 0.07% at full power
  < 0.03% typical levels
IM Distortion:
   < 0.04%
TIM:
   Unmeasureable
Dynamic Headroom:
   > 2 dB
Interchannel Crosstalk:
   > 75 dB at I kHz > 56 dB at 20 kHz
Input Impedances
  50k Ω per channel, without looping inputs 1/2 to Ch. 3/4 or Ch. 5/6
  25k Ω per channel, if looping inputs 1/2 to either Ch. 3/4 or Ch. 5/6
  17k Ω per channel, if looping inputs 1/2 to both Ch. 3/4 and Ch. 5/6
Input Sensitivity:
   1.0V THX Reference Level
S/N Ratio:
   > 118 dB, input shorted, IHF A-weighted
Damping Factor:
   > 800 at 20 Hz
Dimensions:
   19" wide x 7" high x 18.5" deep (7-5/8" high with feet)
Weight:
   71 lbs. net
The Parasound HCA-1206, designed by the well-known circuit designer John Curl, is an exceptionally powerful and versatile high-performance power amplifier certified by Lucasfilm for use in Home THX surround-sound systems. It is also suitable for multiroom audio systems or any other application requiring as many as six independent high-power amplifiers.

With all channels driven, each channel of the HCA-1206 is conservatively rated to deliver 120 watts into 8 ohms, or 180 watts into 4 ohms, from 20 Hz to 20 kHz with less than 0.07 percent total harmonic distortion (THD). Although all its channels are identical, Channels 1 and 2 are designed specifically for the front channels of a multichannel sound system and cannot be bridged. Channels 3 and 4 and Channels 5 and 6 can be switched to bridged mono operation, in which each bridged pair is rated at more than 300 watts into 8 ohms.

Each output channel is rated for operation with loads as low as 4 ohms, although a pair of bridged channels should not be used with loads of less than 8 ohms. That limitation is not due to any lack of current-delivering ability for short intervals, but prolonged high-current operation could create excessive temperatures in the amplifier, which does not have an internal fan.

The HCA-1206 is a large, very heavy amplifier, weighing more than 70 pounds. It is equipped with handles on the front and rear panels. The output circuitry is located along the inner sides of the cabinet, and exterior heatsink fins cover the full depth of each side. The heavy steel top cover is also extensively perforated for ventilation. The output stages use a total of twenty-four 60-MHz, 15-ampere output transistors in matched complementary pairs.

A huge power transformer (which surely supplies a good share of the amplifier's weight) is located in the center of the HCA-1206 just behind the front panel. It is rated at 1.7 kVA (kilovolt-amperes), consistent with the amplifier's potential for delivering more than a kilowatt of clean audio power. Parasound says that the power supply contains more than 120,000 microfarads of computer-grade capacitors. Although the power supply and related components, plus the actual output transistors (four per channel), occupy most of the HCA-1206's interior, there is also a single fairly large circuit board containing the low-level amplifier stages and no fewer than fifteen fuses of various types.

Numerous other circuit and construction features contribute to the unusual character of the HCA-1206. These include cascode Class A input stages, complementary MOSFET high-voltage drivers, and Class A/AB biased output transistors direct-coupled to the speakers without intervening phase-correcting networks. The amplifier also contains a number of temperature sensors and protective relays.

The front panel is comparatively stark. Besides the two massive handles, there is a rocker-type on/off switch, an adjacent LED power light, and six LED's to indicate instantaneous current overload in each of the six channels.

The rear apron actually serves some of the functions usually allocated to a front panel. Six pairs of multiway binding posts, which accept stripped wires or banana plugs, are along the bottom, plainly marked to show their function. Channels 1 and 2 are labeled non-bridgeable, and the others are marked MonoBridge. Small toggle switches above Channels 3/4 and 5/6 are normally set down for separate channels, up for MonoBridge operation.

Across the rear apron, just above the switches, are three pairs of gold-plated phono-jack inputs with small toggle switches between each pair. These inputs are used to "loop" signals from the inputs of Channels 1 and 2 to either or both of the other pairs. That simplifies multiroom stereo installations, allowing the routing of stereo programs to other zones without external jumper cables or Y adaptors.

Finally, across the top of the rear apron are six level-control knobs to balance the volumes in different rooms of a multiroom installation. When the knobs are turned to the dot marked THX (the maximum clockwise setting), the amplifier meets Lucasfilm standards for playback amplifier gain.

Our bench tests of the HCA-1206 were limited to its functions as a two-channel stereo amplifier, although we also applied its preconditioning phase (1 hour at one-third rated power into 8 ohms) to Channels 1 through 4. The top cover of the amplifier became very hot-not enough to bum, but uncomfortable to touch for more than a couple of seconds. During our other tests it ran comfortably cool.

The Parasound HCA-1206 is certainly one of the most powerful and most versatile power amplifiers we have seen in its price range. For Home THX setups or a top-quality multiroom installation, it should be hard to beat (or match, for that matter). After we overcame our initial wariness about pushing the amplifier to its limits, we found it to be as rugged as it feels, looks, and weighs. Perhaps not "bulletproof," but certainly a far cry from some amplifiers we have tested that required kid-glove treatment to avoid self-destruction.

A final note: Parasound's manual for the HCA-1206 is quite specific in respect to do's and don'ts, and on using its operating versatility to best advantage. It is one of the few power amplifiers we have seen that is actually versatile enough to require such information, and it was reassuring to find it provided in a well-done owner's manual.

Obviously, an amplifier of the caliber of the Parasound HCA-1206 is going to do an absolutely first-class job in any home music installation. In my view, this amplifier is about as good as they come.