Product Review

Product Review - Rotel RSP-980 Surround Sound Processor and RDA-980 AC-3 Processor - March, 1997

By J.D. Moretti

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Rotel RSP-980 Surround Sound Processor; Dolby Pro Logic; THX; Frequency response 5 Hz - 20 kHz ± 0.5 dB; S/N Front/Surround 100 dB; Input impedance 47 kOhms; Output impedance 500 Ohms; THD 0.03% @ 1 kHz; Maximum output 6 V; Video input impedance 75 Ohms; Controls: Power on/off, Master volume (motorized), Listening (six inputs), Recording (six), Surround mode - 2 ch, mono, Music 1,2,3 and 4, Dolby Pro Logic, THX, Bass, Treble, Movie Filter, Tape Monitor, 5.1 Channel (for selecting the RDA-980 or other outboard processor); On-screen display; Remote control; Inputs: Six sets of audio (RCA), Five video (RCA), Five video (S-Video), one DB-25 female; Outputs: Three sets of audio (RCA), one set 5.1 (RCA), one DB-25 male, one tape loop, one pair in/out remote jacks, one zone 2 pair of audio; Size 5"H x 17 1/2"W x 13"D; Weight 16.5 pounds; Black metal chassis; $1,300.

Rotel RDA-980 Digital (AC-3) Surround Sound Adapter (outboard processor); Frequency response 5 Hz - 20 kHz ± 1.0 dB; S/N 90 dB @ 1 kHz; Input impedance 75 Ohms; THD 0.008% at 1 kHz; Output impedance 1 kOhm; Output 1.4 V; Inputs: one coax AC-3 RF, two digital coax; Outputs: 5.1 analog line level coax (RCA), one DB-25 male; Controls: Power on/off, Center time alignment (delay) - Center - Rear, Test (volume in each channel), Dynamic range, Input selector (3), Speaker configuration - Front/Center/Surround - Large, Small, None (Center), Subwoofer - yes/no; Size 3"H x 17 1/2"W x 10 1/2"D; Weight 10 pounds; Black metal chassis; $1,000; Rotel of America, 54 Concord Street, North Reading, Massachusetts 01864, Phone (508) 664-3820.

Home theater is just getting better and better. AC-3 (Dolby Digital, DD) has been out for a year or so, DTS is here now, and DVD in April. I can't wait to have it all. The problem is, so many cool new audio/video sources are hitting us . . . boom, boom, boom, . . . it is difficult to buy components that won't be obsolete before the VISA card is paid off. That REALLY scares me, because I don't have the buckaroonies to keep replacing things with the next technology.

The answer to this dilemma is to (1) buy separates (main processor, outboard processor, amps), and (2) make sure that whatever you buy (all-in-one receiver or separates) is forward compatible, namely, extra inputs for future signal sources. There are some receivers out there that have AC-3 built-in, but no provision for DTS, and there are some separates that don't have inputs for 5.1 (AC-3, DTS), so you have to be careful.

The Rotel package we reviewed here consists of a Rotel RSP-980 Preamplifier with Dolby Pro Logic built-in, and a set of 5.1 inputs (RCA and DB-25) for outboard digital surround processors. The Rotel RDA-980 is the AC-3 processor designed to work with the RSP-980, but any 5.1 processor will work with it. One of the things I love about this pair of components is the use of the DB-25 connector. It is a connector commonly found on the back of computers, so cables are available at any computer supply store (one cable comes with the RDA and we bought another one to connect to the amplifier). The DB-25 eliminates having to use 5 coax cables. This makes a huge difference in the ease of connecting the whole thing together. Take a look at this photo of the back of the Rotel package, showing the DB-25 cables plugged in [click here]. Now compare that to a picture I took over the top and looking down at the back of one of our receivers that was being used for another 5.1 setup [click here]. And that receiver photo doesn't even show the mess of wires connected to the AC-3 processor. Look familiar? A double blind test would fail to show any difference between that photo (the mess) and my system at home. Wow! Gimme more DB-25 stuff. You know, I just thought of something. There are a lot more conductors in the DB-25 cable than are necessary for 5.1. Suppose they used the other conductors for two-way communication between the components. Like having a signal that the power amp is overheating sent from the power amp to the main processor, and a message flashes on your TV, or on a digital readout. Or maybe the status of the outboard processor could be displayed through the main processor to the TV or digital readout. This has potential!

OK, I connected the Rotel RSP-980 and RDA-980 together with DB-25, then the output of the RSP-980 to a Rotel RB-985 five channel power amp (100 w/ch) using another DB-25 cable, and to Velodyne F-1500 or M&K MX-5000 subwoofers. Input was from a Yamaha laserdisc player and Audio Alchemy CD player.

The sound of the Rotels was great! The only problem I had was playing CDs in surround modes. Unless the TV was on, I couldn't adjust the levels of the various channels easily. The "Balance Check" button on the remote control is used for this, but on-screen display is the only way to see which channel is being adjusted. You can hear the pink noise coming from the individual channels, but still, there should be an indication on the processor. I consider this to be an oversite at the design stage . . . definitely an inconvenience. But, the sound is really what matters, because I can find fault with any component as far as user friendliness is concerned. So could you. So could anyone. The instruction manual states that the balance between channels is done by using the balance check during the initial set up. For two-channel stereo, this might work, but not for movies or CDs being played in surround sound (Pro Logic and DTS). Time and again, I want to adjust the volume of the center channel with respect to the front left/right or the front with respect to the rear. The "Ctr Fcs" button (Center Focus) on the remote control adjusts the center channel volume one notch, but adjusting the rear is not so obvious. This has to be done with the balance check control. Not all movie sound tracks are balanced the same, and not all CDs either. Hey, just put 6 small LEDs on the front, and a button to select channel volume, left and right arrows to move to the channel you want, and adjust the volume. Or how about just buttons on the remote for master volume, center volume and rear volume, with a left/right balance. Simple. On the other hand, I did like the fact that I could adjust the right rear volume independently from the left rear. Many processors don't let you do that. Even the subwoofer volume could be adjusted with a constant rumble coming from that channel when selected, using the balance check. Cool. Also, the on-screen display works with both standard coax (composite video) and the S-Video connections.

There was some hiss coming from the rear speakers with Pro Logic. The RSP produced a little less than I have heard from other units, but it was there nonetheless. That is typical of suround sound processors.

I was especially impressed with the AC-3 sound quality of the RDA into the RSP. Some of the other units I have heard sound harsh. I used to think it was just the relatively low bit rate of AC-3 that was responsible. Not so. A good AC-3 processor like the RDA-980 makes a big difference. It sounded very smooth . . . no listening fatigue. There are various delay possibilities with both components. Pro Logic delay is 15 - 30 ms, Music has 15 - 90 ms depending on which music mode (Music, Jazz, Concert, and Stadium), and the RDA-980 has its own set of delay times for the center channel and rear, since it plugs into the 5.1 input of the RSP and bypasses the RSP delay functions. Delay for the center is available so that the sound from all three front channels will arrive at the listener's position at the same time. I didn't find the music modes very useful. I have not come across a stereo movie sound track or stereo CD that doesn't have some surround info, so I like the Pro Logic mode with THX when playing any stereo movies or music.

The THX mode adds some "decorrelation" to the rear speakers. Basically, this means that the sound between the two rear speakers is slightly out of phase rather than just simple mono. It makes the rear sound more diffuse. I found the THX mode preferable to straight Pro Logic, and once I heard it, I used it all the time. THX shuts off when 5.1 is selected (for the RDA).

The subwoofer setup was a little tricky. I had to play around a bit with the speaker size selectors on the back of the RDA to get significant amounts of bass to go through to the sub. You can also set switches on the back of the RSP to remove <80 Hz sound from the front (Front Hi-Pass) or rear (Surround Hi-Pass), and speaker size selectors will remove < 100 Hz info from the center and send it to the front left/right. With the subwoofer in use, 100 Hz - 80 Hz will go to the front left/right and <80 Hz goes to the sub. This is very flexible, but can be confusing. It sure was to me. However, after a lot of fiddling, and some cussing, I got the system just the way I wanted it, and everything was fine. Compared to one of our all-in-one receivers, the Rotel was a lot harder to use, but better sound. Guess it depends on what is more important to the user. In the middle of all the cussing, I might have been persuaded to take the easy route, but now that I have it all in check, sound quality . . . definitely. The difference could be due to lot of things. Better circuit parts, the RF demodulation in a separate chassis from the main preamp/processor. Who knows? It was better, and that is what counts. The two Rotel components weigh 26 pounds together. That's more than some all-in-one receivers, with power amps. I would suspect the Rotel package has more substantial (clean as well as strong) power supplies than the average receiver.

All in all, I think the Rotel RSP and RDA components are cool. Not easy to use, but hey, you know? . . . many separates are like that. As soon as we have a DTS processor, it should plug right in, and we won't have to throw anything away. That's really important to me.

J.D. Moretti

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