Infinity RS-4.5 loudspeaker system
Infinity has rarely played the modification game. Only when a new product developed production gremlins and started pooping out all over the map has Infinity taken it back to the drawing board, for purposes of increased reliability' rather than improved sound. The RS-4.5 is the only exception here that we can recall.
Our first pair were among the first off the production line (serial numbers 1002580 and '81). Our immediate reaction was that they had superb bass and high-treble performance but lacked lower middle range and were quite hard-sounding. We expressed our dissatisfaction to Infinity, and were informed shortly thereafter that some changes were being made in the crossover network. Several weeks later, Infinity's chief designer, Bascom King, paid us a visit to make the modifications and assess the results. We agreed that there was a dramatic improvement. The hardness was gone, but we still felt that the lower-midrange performance left something to be desired. There was still, to our way of thinking, not nearly enough gutsiness to the sound of trombones and bowed cellos.
Two weeks later, Infinity informed us that another crossover modification was in the works and asked that we not review the speaker until we had heard the results of that change. We agreed. (We must point out, though, that a number of RS-4.5s had already been shipped to dealers, and that most of them were the second version we auditioned—the one with the tamed hardness but the deficiency of fatness and lowermid-range bite.)
The third version was finally set up in our main listening roam, and we have been living with it for two weeks now. The review which follows is of that version—which is the one Infinity will shipping to dealers as this is being written.
The RS-4.5 comes with an accessory black box—a speaker control center which serves the dual purpose of electronic crossover and equalizer. A front-panel switch selects either mode of operation (while a rear-panel one enables the entire unit to be bypassed, although the input buffer stage remains in-circuit). In either of its in-circuit modes of operation, the control provides eleven different crossover frequencies for the low end of the midrange drivers and the upper end of the woofers. These can be set independently either for overlapping crossovers or for separated crossovers to provide (in theory at least) a slight overall boost or dip through the crossver region, as well as "flat" response. In addition, there are level controls for the woofers and for the tweeters—both providing shelved rather than sloped adjustments—and a level control for overall signal, providing unity gain (no gain, no loss) at its mid setting.
The speakers can, if desired be used without the control center, there are level adjustments on them for midrange and tweeter drivers, as well as a switch that gives flat or tapering response from the woofers.
We tested the speakers in all three operating modes. Without the control center, we found the level-set adjustments on the speakers to be adequate, but barely. There is more than the necessary adustment range on the midrange potentiometer, but the two-position tweeter switch did not give enough range or precision of adjustment to meet all exigencies. With a slightly "hot" input source, for example, it was not possible to reduce the tweeter level to the point where the sound could be listened to without annoyance. Using Infinity's own HCA amplifier and neutral signal sources, the sound from the full-range 4.5s without the control) was generally very good but not outstanding in all respects. Bass was superb—awesomely tight, very deep (measuring flat to 27Hz in our listening room), and very smooth.
The high end was exquisite—very open, and silky-smooth, yet as super-fast as the best electrostatics but without their high-end sizzle (resulting from treble beaming). There were numerous times, though, when the listenability of the sound could have been improved by a slight high-end rolloff (few microphones, disc cutterheads or cartridges are free from high-end peaks)—something it was not possible to obtain without the use of tone controls or an octave equalizer. The high end of the 4.5s is best described as highly analytical (ie, accurate), which is fine for program-evaluation purposes but frequently a liability when listening to recordings that have more going for them musically than sonically.
Many instrumental timbres were only moderately well reproduced. High percussion was rendered flawlessly, but massed-violin sound was judged to be very slightly on the bright side, while lower-pitched instruments were distinctly lacking in warmth. Like the two earlier versions of the system, although to a lesser degree, the ones we ended up with seemed unable to quite cope with the sounds of trombones and bowed cellos. The hackle-raising roundness and blat of the trombone were markedly deficient, as was the gutty bite of the cellos. Woodwinds and violas were less affected, sounding merely a little thin. No further adjustment of the speaker balance controls, or the room placement, could improve matters.
With the speaker control box in-circuit (and the speaker leads reversed—the box is phase-inverting), there was a subtle deterioration in high-end accuracy, characterized by a very slight roughness, but there were gains made in other areas. The ability to overlap the lower crossovers made it possible to bring up the lower-middle range, to the benefit of trombone and cello reproduction, while the tweeter-level control bestowed enough range of adjustment to mate the system to a wider variety of associated components, including hot-top signal sources. With all adjustments optimized, there was now only a trace of brightness, but we were still not happy with what the system was doing to trombones (which are the guts of symphonic and big-band sound) and cellos. At no time did the system have the richness and roundness which is characteristic of live-music sound.
This should not be too much to ask of a speaker costing this much. We have heard systems costing as little as $100 each that rendered cellos and trombones more convincingly (although they did many other things rather badly). It occurs to us in fact that very few of the large and costly systems we have heard in recent years have done a better job of reproducing those instruments than do the Infinitys, but this hardly excuses any of them. We would be inclined to wonder if low-end and high-end range aren't in some way inimical to natural midrange performance, were it not for the fact that we have heard an occasional monster system which could pull off all three with disarming aplomb (and Infinity's SS-1A was one of them).
Other observations: The RS-4.5s will produce very high listening levels in the home—up to 107dB—without strain, but they are not recommended for high-level public-address work because, when they overload, they do it in a rather ungraceful manner, sounding suddenly as though their voice-coils are rubbing. (This, we would guess, is because the midrange diaphragms, which do not have voice-coils anyway, can move just so far and no farther. When pushed beyond that, they just clip the signal in a manner similar to that of a cleanly overloading amplifier.)
The speakers are quite neutral insofar as perspective is concerned. They reproduce sounds at the proper apparent distance, being neither up-close nor backed-off. Stereo imaging is excellent but not superb, as a result of some very slight phasing-interference effects between the tweeters and the midrange drivers. (A slight vertical-venetian-blind effect is audible with pink noise and, to a lesser extent, with program material.)
Biamping the system, with the Infinity HCA and an Audio Research Dual 150, brought about the expected improvements in low-end detail (moderate) and overall cleanness and definition, but could not change the speaker's basic attributes. (Highs or lows were slightly degraded, depending on which amplifier was handling the upper or lower range, but we only had one HCA on hand. And we wonder how many people are going to shell out $8000 for the relatively small improvements incurred in going from full-range to bi-amp operation with that amplifier.)
The RS-4.5 has a lot going for it, and is already good enough that many audiophiles may never again feel the need for upgrading to something "better." But the fact that some systems that are vastly inferior in other respects (and a lot cheaper) are nonetheless more accurate reproducers of certain musical timbres does justify, to our way of thinking, some rather strong reservations about the RS-4.5. (See the "Audio Verity" in Vol.4 No.3.)