Parasound R/EQ-150 5-Band Equalizer.

Manufacturer: Parasound Products, Inc., 950 Battery Street, San Francisco, CA 94111; 415/ 397-7100

Price: $145

Source: Manufacturer loan

Reviewer: Howard Ferstler

The last time I wrote anything about equalizers in this magazine was in my "Skeptimania" column in Issue 68, wherein I noted that I had (and still have) mixed feelings about them, even though I am aware of the interesting things they can do. I also noted that my biggest problem with the use of equalizers involves their misuse by typical users.

Usually, this involves this involves trying to use them as "super tone controls" to correct for deficiencies in specific recordings, rather than using them for what they should be mainly designed to do: correct for moderate (not extreme, please note) room and speaker-system anomalies. While correcting for room/speaker problems can often be a tedious process even with a good real-time analyzer to verify the results, attempting to use an equalizer to correct perceived deficiencies in every slightly sub-par recording that comes along will be an exercise in futility.

However, using an equalizer to make modest room/speaker corrections can often result in a good system sounding even better, but only if the system and the equalizer are able to get along together. For example, in Issue 68 I noted that after working long and hard with a ten-band (one octave) equalizer to correct for what amounted to a few fairly modest and narrow-band, frequency-response problems with the biamped center speaker in my main system, I did manage to achieve fairly good results.

However, I also increased the noise level of that channel considerably, because of the rather radical corrections and counter-corrections required to handle the overlap between bands. The more sliders you move off center, and the further you move each of them off center, the more noise a typical graphic equalizer will generate.

In the end I found that I could achieve somewhat better results, and do so more easily, by employing a thirty-band (one-third-octave) unit to smooth out every little dip and peak, without the need to also use a multitude of counter corrections to null out the overlap that inevitably happens when using equalizers having one-octave-wide control settings, with their typically rather broad correction slopes.

So, when I got a chance to review the Parasound R/EQ-150 equalizer, I was both skeptical and curious. This is because it is only a five-band unit, with control points centered at 40, 80, and 120 Hz in the bass range, and at 2.5 kHz and 6 kHz in the upper ranges. Each of those adjustments is capable of applying only a modest +/- 8 dB worth of correction to both stereo channels at once, and supposedly can do so with the bulk of the correction applied to bandwidths only about one-half octave wide. While this somewhat narrow bandwidth-control range might be an advantage when trying to control a typical peak or null centered at or near those specific points, the rather extreme spacing between some of the adjustment frequencies, and the fact that it cannot independently adjust each channel, gave me the impression that the R/EQ-150 might be of very limited use.

This equalizer is an extremely basic looking piece of equipment. For one thing, it is surprisingly small, being only 9.5"W x 1.75"H x 7"D. It is also basic in its hookup arrangement on the back panel: one pair of stereo inputs and one pair of stereo outputs. Other than a robust-looking, three-pin A/C connector for the power cord, that's it. There are no tape-monitor in/out jacks to allow the user to insert the unit into a tape loop and still hook up a recorder, nor are there any kind of set-and-forget, rear-panel switches. This is a basic equalizer, period.

This is the first unit I have encountered in this size/cost category that comes equipped with a detachable, "audiophilegrade," three-prong power cord. This fact becomes even more interesting when you consider that the R/EQ-150 dissipates only 5 watts of power. Although it is nice for the owner to be able to shop around for a replacement cable to better integrate the unit into an installation so that a minimum of cable will be hanging down behind the equipment rack, it does seem a little like overkill to have this kind of formidable A/C connector, and its accompanying, rather thick 18 AWG cord, included with a diminutive, $145 equalizer. Well, it looks pretty darn impressive ...

The front panel, while not as basic as the rear, is still pretty Spartan. From left to right, and lined up in a row, we find the five adjustment controls (these are knobs, not the usual graphic-equalizer-type sliders), followed by a bypass button (with indicator light), and an overall level control. Note that there is no on/off switch. The unit is either left on all the time, or controlled with some kind of external device. I will note that it should be impossible to plug the three-prong power cord into the switched convenience outlet of most preamps, and probably all receivers.

The equalizer comes with an informative instruction manual that tells the user about what the unit can do and what its specifications are. The R/EQ-150 has a two-year warranty that includes parts and labor.

While the frequencies selected for equalization are widely spaced compared to typical equalizers, it is important to remember what kind of anomalies are encountered in typical room/speaker interactions. Each of the R/EQ-150's boost/cut controls are designed to zero in on a specific problem area that might show up in a normal sound-system installation.

For example, the 40-Hz and 80-Hz adjustments can be useful in compensating for the inherent bass limitations of some smaller speakers, particularly when they are positioned in non-optimal locations. In addition, they can at least partially deal with minor, room-induced, bass peak and/or dip problems that might be audible at certain listening positions.

It is not a good idea to try to deal with such artifacts too vigorously, because fixing a standing-wave problem in one area will probably make for a worse problem somewhere else in the room. However, the adjustment flexibility of those controls, the limited adjustment range possible (which minimizes the possibility of overdoing things), plus the existence of the "bypass" switch, should allow careful users to do some reasonably decent fine tuning.

The 120-Hz control can be very handy with stand-mounted speakers, or speakers that must be placed within certain distances of a side wall or front wall. That kind of positioning can sometimes result in a degree of mid-bass suckout. I believe that it is best to correct for such artifacts by repositioning the speakers, but if this cannot be done, or if repositioning can only partially fix things, it is possible that the 120-Hz slider will be of help.

The 2.5-kHz control is one that many owners of two-way speakers, and even some three-way models, might find of use. In many such systems, 2.5 kHz is right at or at least very near the woofer/tweeter or midrange/ tweeter crossover point and in a lot of cases, there will be a power-response notch there that might be audible in some listening rooms. This will particularly be the case if the listener is back some distance from the speaker, where the reverberant field dominates over the direct field. Up close and with the enclosures aimed at the listener, such speakers might sound terrific, because they would be optimized for a uniformly flat direct-field response. However, at a longer listening distance they might have a bit of reticence in the midrange that the 2.5-kHz control can compensate for by means of a slight boost.

Finally, we have the 6-kHz control. I have rarely found a need to boost things at that frequency, but I have found speaker systems that were a bit hot out near that range, particularly in rooms that were somewhat reflective, and with some of them it is quite possible that the 6-kHz control will be able to knock off some of the edginess that might be audible with certain kinds of program material.

Although it can easily be integrated into any system one might choose, the R/EQ-150 is basically designed to be used as a remote unit, working with a remote power amp (such as their own "ZAMP" unit, reviewed by KWN in Issue 70) to drive small box or in-wall speakers in another part of the house. I found that it could hold its own in my main listening room, with some speakers, where it could correct for some of the room-generated deficiencies that even good reproducers sometimes fail to deal with adequately.

However, I also must note that it is going to be difficult in the extreme to make intelligent use of a unit of this kind without a decent measurement device, and I am not talking about a SPL meter, or even a one-octave-measuring, real-time analyzer (RTA). Because we generally will be most interested in smoothing out room-response anomalies, it is almost mandatory that a good 1/3-octave RTA, such as the AudioControl SA-3051, be employed during the initial installation phase. Just because this equalizer is a low-cost item, does not mean that it does not demand respect during the setup phase.

A good dealer should be able to at least loan you a measuring device of this kind, and may also be able to supply an operator to go with it. I cannot stress too much the need to intelligently install an equalizer in a system with the assistance of a proper measuring device. (See my remarks in Issue 68).

Before installing the equalizer in my smaller system, which because of the way the satellite speakers are positioned is in need of full-time equalization, I did some direct measurements of the R/EQ-150's outputs while adjusting each of its controls.

First, I determined that the "bypass" switch is really capable of allowing the signals to bypass the equalizer circuitry. I consider this important, because in a high-quality system -- one that did not need equalization when its main speakers are playing, but which might need help when remote speakers powered by the same amplifier are playing by themselves in another part of the house -- it is nice to be able to completely bypass the equalizer circuitry when engaged in "serious" listening with those main speakers. Some signal processors have a bypass or disable switch that does not really bypass. Congratulations to Parasound for including one here that does.

I next measured the boost and cut abilities of the unit. The 40-Hz control could apply about 8 dB of boost centered at the selected frequency, with the slope beginning at about 80 Hz. This is a very steep adjustment curve, considerably more able to influence the bass in the 40-Hz range than a typical tone control. Indeed, with a smaller speaker, this particular knob as so capable that I would consider using it in place of a tone control to fine-tune the bass sound of a lot of recordings. (So much for my previous admonition about not using an equalizer to compensate for recording deficiencies).

I will note that with the boost applied, the bass below 40 Hz was rolled off rapidly (remember, this is an equalizer control that is centered at 40 Hz, not a full-bass boost control), which will be a good thing with small speakers needing a reasonable amount of boost, but which would not be able to deal with strong boost at extremely low frequencies. I will also note that cutting the bass with the control tends to do a relatively equal amount of cutting to all frequencies below about 60 Hz.

The 80-Hz control did pretty much what it is supposed to do. The boost and cut ranges extended from about 160 Hz on the high side, on down to about 40 Hz on the low side. I realize that this is considerably more width than 1/2 octave, but the range of maximum boost and cut was contained within the prescribed narrow limits. Between about 50 Hz and 80 Hz, an area roughly 2/3-octave wide, is where the maximum effect occurred. This is a considerably tighter area of coverage than what would normally be delivered by typical one-octave equalizers with the same center frequency.

The 120-Hz control was similar in terms of performance to what was delivered by the 80-Hz control. Actually, a bit better. The maximum boost and cut range was somewhat narrower in bandwidth than what I measured at 80 Hz, and the center frequency was just about where it was supposed to be.

The 2.5-kHz control was a bit less tight than the bass controls, with the boost and cut maximum levels being about one octave wide, and the slopes beginning at about 1 kHz and ending at about 5 kHz. I will note that although they were in no way as narrow as what would be possible with a 1/3-octave unit, they were considerably less broad than what I have encountered with some one-octave units.

The 6-kHz adjustment was almost perfect. The peak boost occurred in the range between 5 and 8 kHz, and the boost slopes began at about 3 kHz and leveled out at about 12.5 kHz. This is a useful range and I have no doubt that a lot of speaker systems would benefit from a judicious use of this control, particularly the cut feature.

To test the effectiveness of the R/EQ-150 on a real audio system, I installed the device in my smaller ensemble: the one my wife uses for talk movies and which occasionally we both use for more demanding entertainment, both movie and audio-only.

Among many other things, this system consists of a pair of Allison LC-120 speakers as main left and right units. These are ordinarily very fat-responding speaker systems. However, they are designed for floor positioning and I have stationed them on a 30-inch-high bench, about two feet from either side wall and out from the front wall a bit more than a foot. They are located this way because that is the only way they can be installed in this particular system. (In spite of being designed for floor use, they are actually fairly short, which does not make them tower too high when on the bench). Because of their relationship with those boundaries and the symmetrical arrangement of the speakers, each exhibits a similar-frequency bit of suckout in the midbass, and the low bass is rolled off a tad, too.

Normally, I use an AudioControl Ten Series III equalizer with this pair (this is the same unit that I replaced as a center-channel equalizer in my big system), and it does an extremely good job in this room. Unlike with the bigger system's center channel, where the Ten Series III ran into some problems, the corrections required in the smaller system's main speakers do not require a lot of counter corrections, due to the rather broad nature of the anomalies that result from the less-than-optimal speaker placement. I also normally use a Velodyne FSR-12 to eliminate the above-noted problems in the low bass, but for this little exercise, I did not engage its talents.

It was an easy trick to temporarily replace the Ten Series III with the R/EQ-150, and it was nearly as easy to apply a judicious amount of boost at 120 Hz to nearly eliminate the suckout artifact from the response curve. I was surprised that this could be done so easy with the R/EQ-150, because the corrections required with the Ten Series III were a bit more extreme. The system also displays a mild peak at about 2.5 kHz (no doubt due to the reflectivity of the nearby side walls in this particular room), and the equalizer handled that problem with a very slight cut of the 2.5 kHz adjustment.

Aside from a mild 4-dB peak at 125 Hz, the result (as verified by a series of moving-microphone readouts at the listening couch made by my SA-3051) was a response of +/ -2 dB from 40 Hz to 12.5 kHz. Aside from the peak, this curve was nearly identical to what I could get with the Ten Series III. Given that the latter has twice the number of equalizer controls as the R/EQ-150, is four times its size, and costs about 50 percent more, the Parasound unit's accomplishment was very impressive.

Overall, I would have to rate the R/EQ-150 as a very satisfactory unit. For one thing, its noise level is very low with the controls set at their extremes; lower than that of the Ten Series III at similar boost and cut settings. In addition, it appears to be well made, as is the AudioControl equalizer. There is no doubt that it can deal with any speaker/room anomalies that happen to be centered close to the adjustment centers of its five control knobs, and those anomalies are more common than a lot of people might think.

Individuals with smaller systems that need a frequency-response fix at the specific points that it can deal with will probably find this unit very useful. Even those who have fairly upscale systems, assuming that the installation has similar frequency response problems, might find the R/EQ-150 equalizer quite to their liking. In addition, its bypass function will allow them to integrate the R/EQ-150 into a larger system that may benefit from the ability to equalize any small, "remote" speakers that are connected to the "Speaker B" outputs of the amplifier or receiver. When the higher-quality, "Speaker A", main speakers are playing and the remotes are not in use, the equalizer can simply be bypassed at the push of a button.

Conclusion: At $145, the R/EQ-150 is an extremely good buy, and some dealers may discount it even further into the "true bargain" category. - HF