Yamaha RX-1100U Stereo Receiver
Of all the audio-video receivers we've tested to date, the Yamaha RX-1000U is arguably the most sophisticated. It is certainly a far cry from the typical models that combine mediocre audio behavior with basic video switching, all in the hope that the novelty of the combination will obscure the lack of high fidelity performance and features. Instead, Yamaha has taken an essentially no-compromise audio receiver and built into it not only the switching for video and its associated audio, but for a video processor as well.
The only major function that is omitted is TV tuning. But many audio-video installations these days depend on a cable decoder to select and tune stations, while the tuners built into VCRs perform the same function during recording. Therefore, the absence of a TV tuner in the RX-1100U cannot be considered a loss.
The back-panel audio-video connections are groups of three pin jacks: one each for left and right audio and one (with a yellow insulator) for composite video. There are sets of inputs and outputs for two VCRs, and an input for a videodisc player. A lone composite-video output feeds a TV receiver or monitor. As for audio components, connections are provided for two tape decks, a CD player, and a turntable. The phono jacks have a pushbutton nearby to choose between the MM (fixed-coil) and MC (moving-coil) modes.
A supplied loopstick antenna mounts on the back panel and feeds the AM inputs, which are the insert-and-lock type intended for bared wires. For FM, there's just a 75-ohm coaxial input- which, unfortunately, is the incompatible slip-on type rather than the threaded F connector common on other U.S. equipment. However, a slip-on male RF-cable plug (a pseudo-F connector, to coin a phrase) will mate to the unthreaded female chassis socket. Yamaha supplies a slip-on balun transformer to match a 300-ohm twinlead to this input, and the usual floppy dipole antenna to match the balun.
There also are control cables to interconnect the RX-1100U with other Yamaha components in the RS Series so that the receiver's supplied wireless remote can control them, too. As many as three pairs of speakers can be connected to the heavy-duty binding posts, which accept bared wires or banana plugs. The switching is arranged so that when the B and C pairs are both in use, they are connected in series with each other and in parallel with the A pair (if it, too, is on), making the latter the output of choice for critical listening. The only other back-panel feature, aside from the AC convenience outlets, is a pair of jumpers that can be removed if you want to insert a component (say, a surround-sound processor or an equalizer) between the preamp and power sections of the receiver.
The front panel's main audio controls run horizontally across the middle of the unit. The less-used audio controls are hidden behind a typical Yamaha-style door, the inside of which is labeled with the control identifications. Video processing controls and pilot lights for related functions (simulated stereo and a noise processor) are at the top center of the unit. All audio level controls (volume, loudness, and "muting"-actually, a 20-dB attenuator) are at the right end. The 1100's volume knob is motor-driven, and its index is a short fluorescent orange line that makes the setting visible from across the room.
The supplied RS-RX11 wireless remote, which is powered by two AA cells, includes a main on/off button, all of the selectors of the RX-1100U's front panel, steppers to select station presets, the 20-dB "muting," and volume. If you have matching RS Series components in the rest of the system, the remote can cue the turntable, control basic CD-player functions, and cause the selected audio deck or VCR to play, cue, or record tapes-or even switch between transports on dualcassette audio models.
The main front-panel selectors, which choose the signals for monitoring and include all of the inputs plus the built-in AM/FM tuner, are large square buttons. If you press one that represents an A/V source, its pilot light glows red and its audio signal will go to the speakers. If you then press one representing an audio-only source, its pilot glows red and the first pilot turns green, which indicates that the video is still supplied by the A/V source even though the audio comes from another input. This makes possible simulcast (TV/FM) reception or recording.
Among the less-used controls are two recording selectors, one for video and one for audio. The one for video offers a source position that will feed the monitor settings (including those for simulcasts) to both VCRs or permit them to dub from each other or from the videodisc player. The audio recording output takes its primary cue from the source position of the video selector, again accepting whatever is chosen on the main (monitoring) selector. If the video selector is on any position other than source, however, the audio selector becomes live and can choose videodisc, either of the VCRs, audio Tape 1, CD, or phono (but not the tuner) as its source and record it independently. This complicated design isn't aided by an owner's manual that, while often clearly written as far as it goes, seems unwilling to admit that the RX-1100U is as complex as it is. Thus, the manual glosses over many points that could profit from fuller elucidation.
Next to the recording selectors are three switches for audio modes. The mono/stereo button can be used, among other things, to feed the output of a mono VCR to both channels of the preamp. The simulated-stereo option is a pair of complementary comb filters (nulls are at 150 Hz and 4.6 kHz in the left channel and just above 1 and 20 kHz in the right, according to the lab tests). Like most of the breed, Yamaha's system creates a sort of fuzzy openness that fails to enthuse us. The proprietary DNC (Dynamic Noise Canceller) circuit is a dynamic filter that cuts highs to attenuate hiss exposed by low signal levels but opens up to pass the full bandwidth as the signal level rises. In our experience, no filter of this sort operates completely unobtrusively; the Yamaha design is perhaps better than most, though this is a very subjective matter. The DNC may be most useful with substandard audio from video program sources.
Also located on the subpanel behind the door are the balance control and the three tone controls (bass, midrange, and treble), plus a tone-defeat switch. Filling out the sub-panel are the three speaker-pair selector buttons and the headphone jack.
The tuner controls run in a narrow band just above this subpanel, stretching from the main power switch almost to the volume control. In manual/mono tuning, the tuning bar steps up or down by half-channel (0.1-MHz) increments on FM, by full-channel (10-kHz) increments on AM. In addition, there's a fine-tuning bar that microsteps by 0.01 MHz on FM and 1 kHz on AM. Tuning can also be automatic/stereo, seeking out the nearest receivable station in either direction. The automatic-mode button is also used to restore stereo reception once you've tuned an FM station manually.
For FM, there is an IF (intermediate frequency) stepper that offers three options: wideband operation for maximum signal quality on stations that suffer no interference from others nearby on the dial; narrowband for those that suffer from undue competition; and automatic, which chooses electronically between the first two on the basis of reception conditions. You'll probably leave the receiver in the latter mode most of the time. When you place a station in the preset memory bank, the reception mode is memorized along with the frequency. There are eight preset buttons, holding a total of 16 stations-AM or FM, in any mix-in two banks.
Video enhancement, which can be bypassed with a nearby pushbutton, consists of two rotary controls, one each for video signal level (brightness) and detail. We have encountered some commercial videotapes that could profit from the level control, though most videophiles probably will use it less often than the detail control. The latter has only a moderate adjustment range (if you forget to turn it off, the results won't be disastrous). You can smooth out the harshness or graininess that some cable operators add in the name of improvement, or you can add some of those same characteristics to other pictures.
As is typical of such controls, it achieves its effect by boosting or attenuating the high frequencies in the video signal. In Diversified Science Laboratories' measurements, there is a slight boost (up to 3/4 dB above 3 MHz) when you turn on the processor with this control at its center detent. Turning it to maximum further increases this effect in the highest bands but boosts the 1.5- and 2.0-MHz bands the most-by 3-1/4 and 3 dB, respectively. Turning the control to minimum introduces a dip of 2 and 1-3/4 dB, respectively, in these same bands.
The luminance control ranges from 83 to 155 percent of normal signal level-not nearly great enough to create fadeouts in dubbing but, by the same token, not extreme enough to give you a really bad picture if you leave the control at either extreme. There is a slight boost (to 108 percent) even with the processor turned off. There also is a slight rise in chroma level (color saturation), which is up 1/2 dB with the processor off and up 1 dB across the entire spectrum with it on. Outside of this minor vagary, chroma performance is essentially perfect.
FM tuner performance is in the ballpark with that of other high fidelity receivers-and therefore notably better than in some quite expensive audio-video models. The losses in separation and distortion with the narrow IF bandwidth are to be expected; they are the price that must be paid for the added selectivity. However, as is usually the case, the actual selectivity figures aren't as clearly ascertainable. In the narrowband adjacent-channel test, the tuner tended to jump to the interfering carrier and wasn't consistent about the level at which this happened, preventing a single-number evaluation. In the alternate-channel test, the wideband setting proved asymmetrical in response and the figure shown is for that reason only approximate.
We particularly appreciated what Yamaha calls the "signal quality" indicator, which registers signal strength minus multipath in five steps. The thresholds range from 27 to 43 dBf in increments of approximately 4 dB. This is precisely where the information is most needed for antenna orientation (if you have a rotator), and the steps are close enough to permit fine-tuning. The layout and calibration (0-100 percent) of the indicator suggest that nothing beyond its range in either direction could possibly be of interest. That isn't true, though the outer fringes do represent diminishing returns.
The rolloff at the low end of the FM response, which is less severe than we see in many receivers and tuners, isn't entirely due to the tuner itself. Yamaha seems to have deliberately delimited the receiver's frequency response, possibly to reduce the opportunities for intermodulation with so much going on in its circuitry. In particular, a useful infra-sonic filter is built in (and even listed in the specifications), rolling off at about 12 dB per octave below 10 Hz. The result of the bandlimiting is a slight droop at both ends of the audible spectrum: to - 3/4 dB at 20 Hz and to almost - 1/2 dB at 20 kHz. Only under very unusual conditions will these deviations become audible.
With the tone controls engaged but set at their "defeat" detents, the droops increase to about - 1 dB at both extremes, which still isn't severe enough to induce most users to turn off the tone controls. The tone controls themselves are well-behaved, with fairly even increments per calibration mark. Bass has maximum effect of about ± 11 dB near 30 Hz, with almost no effect above 1 kHz. Midrange reaches from about 100 Hz to 10 kHz and achieves the surprisingly wide adjustment range of + 13'/2, -12 dB just above 1 kHz. Treble starts at about 1 kHz and peaks near 13 kHz, with a range of roughly +11, - 10dB.
Loudness compensation is unusually complex. As in many of its most sophisticated models, Yamaha has provided a loudness adjustment ring outside the main volume control. The idea is that you set the volume (with the loudness all the way up) for "full" listening level, based on your listening habits, room acoustics, and speaker sensitivity. Then, when you want loudness compensation, you reduce output by turning down the ring rather than the main control. This attenuates frequencies around 1 kHz more than the bass or the extreme treble, though the exact curve depends, to a considerable (and, in some ways, unpredictable) extent, on the setting of the loudness control in this instance. Of course, the tone controls give you unusual flexibility in tailoring the supplied compensation if you don't like it.
Phono response is exceptionally flat between the frequency extremes, where rolloff is slightly greater in the moving-coil mode than through other inputs and slightly flatter in the fixed-coil mode. Impedances and levels are generally well chosen. The output to tape from the aux inputs (actually measured through the CD jacks) is substantially direct, as you would expect with a separate recording selector. Still, the receiver does add an ignorable 50 ohms to the output impedance of the source component.
Rating of the power amp at 125 watts (21 dBW) into a minimum of 6 ohms proves conservative. Some receivers that supposedly will handle 4-ohm loads quake at the 2-ohm test, putting out less power (because of current limiting) than they do into 4 ohms. The Yamaha continues to pump out more power as impedance and duty cycle are reduced. We don't recommend taking undue advantage of this forgiving trait, but it's good to know that if you observe Yamaha's caveats (no less than 12 ohms per speaker in the parallel hookups or 3 ohms per speaker in series), you will stay well away from any ragged edges.
While the RX-1100U is not completely equivalent to its best sibling audio-only models, it comes closer to that ideal than do many top audio-video models in other lines. Its range of features-particularly the handling of FM IF bandwidth and the tone controls-is far above the call of audio-video duty and is rivaled by relatively few audio-only models. The switching, though complex, is more straightforward than that for comparable features in some of the competing gear we've tested. And the basic audio capabilities and performance are better than you're likely to find in any audio-video receiver.
