Index to Articles

 

Product Review - March, 1995

By John E. Johnson, Jr.

Divider


Parasound P/SP 1000 AV Processor/Preamplifier Parasound HCA-1206 Six Channel Power Amplifier.
Surround sound processor/preamplifier. Stereo inputs (all line level) for three audio/video sources (including three S-Video as well as coaxial - RCA jacks) and two audio sources (coaxial - RCA). One stereo pair of audio inputs which are connected to the processing circuitry when the P/SP 1000 is on, and directly to a pair of "bypass" RCA output jacks when the unit is off so that a separate preamplifier can be used for non- surround sound music if desired. Outputs include two S-Video and three coaxial RCA video, one stereo pair of audio "bypass" RCA jacks, one each of front left, front right, center, rear left, rear right, and subwoofer RCA jacks. Rear panel switches for center channel - small, large, and none. Rear panel switch for subwoofer crossover rolloff of 12 dB/octave at 80 Hz, 120 Hz, or full range. Front panel switch for Power, input selector buttons for Laserdisc, Video 1, Video 2, Tape, Line (for use with "bypass" outputs), and Preamp Direct (routes all audio inputs through preamp circuitry but not through surround processing circuitry). Signal processing options include Dolby Pro Logic, Stadium, Hall, and Club. Special function options include Unified Surround Field and Bass EQ. Frequency response 20 - 20 kHz plus or minus 1 dB, harmonic distortion less than 0.06%, depending on mode and channel. Size 3 1/2"H x 19"W x 13"D, weight 16 pounds. Black metal chassis, grounded AC. $850. Parasound Products, Inc., 950 Battery Street, San Francisco, California 94111, (800) 822-8802.

Divider


Parasound HCA-1206 Six Channel Power Amplifier
Six channels of power amplification, 135 watts rms per channel at 8 Ohms, all channels driven simultaneously. When bridged, 300 watts rms per channel are available for two channels, and 135 watts per channel are available for two channels (bi-amping configuration). Looping switches feed input signal to additional channels. Frequency response 20 - 20 kHz plus 0/ minus 3 dB, harmonic distortion less than 0.07%, input impedance 50 kOhm, slew rate 130 V/microsecond, damping factor 900. Size 7"H x 19"W x 18.5"D, weight 71 pounds. Black metal chassis, grounded AC. $1,950. Parasound Products, Inc., 950 Battery Street, San Francisco, California 94111, (800) 822-8802.

The P/SP 1000 is Parasound's first surround sound processor/preamplifier. Long known for the high quality of their preamplifiers and power amplifiers, Parasound has entered the home theater market as a major contender with this electronic component. It is a "separate", meaning that you will need a power amplifier with at least five channels of amplification to use the processor in surround sound modes. We obtained the Parasound HCA-1206 six channel - 135 watts rms per channel THX certified power amplifier for exactly this purpose, and report the results on both units here.

One of the drawbacks of using a surround processor that is not integrated with the power amplifiers is that you need five interconnect cables. This can not only be expensive, but it creates a literal telephone exchange-look to the backside of the equipment rack. However, notwithstanding the positive aspects of having the power supplies and circuitry of the sensitive preamplification side separated from the high current carrying power amplification side, there is another, perhaps just as important factor: flexibility. All surround sound processors have controls for the individual channels. We found that being able to control the channels (volume) in a general way from the processor, plus fine tune the volume of, say the left and right rear speakers individually, using the volume controls of the power amplifier (in this case, the HCA-1206 has input level controls for all six channels), we could obtain a balance of surround sound that was all but impossible with standard integrated surround sound receivers.

The P/SP 1000 has a rack mount styled chassis with the controls laid out simply on the front. No alphanumeric readout displays or complex programming: just power on/off, input selector, signal processing, and special functions. Although the processor has the usual "stadium" and "hall" modes that are found on most processors, surround sound is present on enough television programs, as well as practically all VHS tape and laserdisc movie material, that Dolby Pro Logic is the processing mode of choice. However, the other modes sound very nice if you are listening to a stereo non-surround sound source and want to liven it up, or just have a little variation.

We tested the P/SP 1000 with several sources, including broadcast TV programming. We utilized a good subwoofer in all our tests, and the processor has a subwoofer output that is controlled on the back with a switch for crossover frequency (80 Hz, 120 Hz, or flat, i.e., full spectrum). Since our subwoofer has a built-in crossover network, we switched to "flat" so that the low frequencies would not be passing through two crossover networks.

In spite of the spurious noise contamination that can be injected between the broadcasting studio and the input jacks to the processor, the P/SP performed quite well with television programs. Vocal information (dialogue) was centered, stereo left and right front had good depth, and the rear surround added the head turning sounds that gives surround sound the impressive effect for which it is intended. The P/SP 1000 utilizes the PMI 2126A chip for decoding.

When fed a pure mono signal, we found that there was a slight crosstalk of the sound - which, if surround processors were perfect, should only be coming from the center channel speaker - to the front left and right channels. This occurred at all sine wave frequencies that we tested: 16 Hz, 24 Hz, 50 Hz, 100 Hz, 1 kHz, 5 kHz, 10 kHz, and 15 kHz to about the same degree. However, we had to turn the center channel volume all the way down, and the main volume control up to hear this. The crosstalk did not occur to any significant extent into the rear surround channel speakers. When we fed the system an out of phase voice, it came strongly from the rear channel, as it should, and again, there was a slight crosstalk into the other channels. A certain amount of crosstalk is normal.

You might be interested, but perhaps not surprised, to find that science fiction programs had the best surround sound, followed by the commercials (wouldn't you know they would scramble to make use of surround sound), and then regular mundane programs that don't have any engine room sounds or explosions.

We can't overemphasize the necessity of having a good subwoofer. That is why the P/SP 1000 has a flexible output for this signal, and the HCA-1206 has a sixth channel of amplification, just in case you don't have a self powered subwoofer.

Speaking of bass, there are several features of the P/SP 1000 that affect this. Setting the center channel selector switch (on the back) to "small" diverts some of the low frequencies of the center channel to the left and right front channels. With the setting on "large", the center channel receives all the information intended for it, while a setting of "none" (phantom) sends most of the center channel information to the left and right front channels. "Bass EQ" boosts the 40 - 70 Hz region of all channels (except the subwoofer output) by 6 dB, in case all the speakers are of the small, compact design that is so popular right now.

The USF (Unified Surround Field) switch blends some of the center channel information into the left and right front channels for a "seamless soundstage".

The rear channel delay can be set to 15, 20, or 30 ms depending on the preferences of the listener and size of the room. We preferred 15 ms, as the room we tested this system in was small.

For testing purposes, the P/SP has an internal pink noise generator that is accessible from the remote control. When activated, pink noise is generated in the following order: front left, center, front right, both rear surrounds, then off. According to the schematics, the pink noise is inserted before the decoding chip, so it can be used not only to set volume levels, but as a diagnostic tool for testing the surround sound steering. The remote control unit also activates power on/off, volume (motorized), the various inputs, and processing modes.

There are two modes for the audio purist group: one is the preamp direct, in which all audio input signals are shunted past the signal processing and are only preamplified; the other requires the use of the line/audio inputs and bypass outputs, where the audio signal merely passes through the processor inputs to the outputs without going through any of the processor or preamplifier circuitry. The unit must be turned off to activate this, and it is a feature that would be used if one has another preferred preamplifier for audio use, with the P/SP 1000 being used only for surround sound processing. In our opinion, the P/SP 1000 preamplifier sound quality is of a high level, such that another preamplifier is unnecessary. Utilizing various CDs with upper register violin solo lines, female voices, piano, full orchestra, and so on, we found that the P/SP 1000 and HCA-1206 make a definite "high end" kit with the corresponding sound that goes with this terminology. Sibilants are clean; accuracy and sound stage are excellent. The 135 watt rms per channel delivery is sufficient for just about any sound level that could be wished for, even using speakers of modest sensitivity.

The HCA-1206 is very solidly built, weighing a hefty 71 pounds, with a rack mount style chassis. MOSFETs are used for the driver stage, while bipolar devices are use in the output stage. It can be configured for full six channel operation, or for just a few channels by bridging with switches on the back. Besides a power on/off rocker switch on the front, there are overload indicators for each channel. However, we did not see them activated even once, a testimony to good power supply construction. The binding posts will accept bare wire, banana plugs, and spade lugs. The RCA jacks on the HCA are gold plated, as they are on the P/SP. The instruction manual states that the HCA can get very warm, but we did not find this happening at all during our tests. This is probably due to the massive heat sinks which are on the sides of the unit, plus we did not place the amplifier in an enclosed cabinet where there would have been shelves above it.

Although Dolby Surround AC-3 (TM) is just becoming available, it will only be encoded on laserdiscs for the time being. Television broadcasts will not incorporate this type of surround sound until HDTV is marketed, and VHS movie rental tapes will continue to be encoded with standard Dolby surround rather than AC-3. Therefore, the answer to the question that everyone asks as to whether to buy a Pro Logic processor now, or wait until high quality AC-3 decoding processors are available, depends on (1) how long you are willing to wait, and (2) whether laserdiscs are the primary TV viewing format in your home theater.

In sum, the P/SP 1000 and HCA-1206 are state of the art home theater electronics with very high quality sound which should satisfy just about any home theater aficionado. We highly recommend that you audition both of these products.

John E. Johnson Jr.
Editor-in-Chief


Copyright 1995, 1996, 1997 Secrets of Home Theater & High Fidelity
Return to Table of Contents for this
Issue.