Luxman L-430 Integrated Amplifier Review
Luxman's top-of-the-line integrated amplifier, the L-430, is rated to deliver 100 watts per channel into 8-ohm loads with no more than 0.018 percent total harmonic distortion from 20 to 20,000 Hz. In addition to the usual amenities provided with top-line integrated amplifiers (moving-coil and moving-magnet cartridge inputs, etc.), the L-430 has some common controls that work in an unusual way.
For example, the tone controls are eleven-position detented knobs. That doesn't seem too unusual until you notice that those detents are calibrated in terms of nominal "turnover frequency" (1,000 to 10,000 Hz for the treble control, 20 to 400 Hz for the bass). Turning the treble contol to a lower Hz setting increases the boost or cut effect as does turning the bass control to a higher Hz setting. As Luxman's informative instruction manual points out, these controls simultaneously shift the frequency at which the control takes effect and the amount of boost or cut.
In addition to a tone-control-defeat switch, there is a phono straight control which, when pressed, bypasses the balance control, tape monitor and selector switches, and the stereo/mono switch. The phono-preamp output thus feeds directly into the volume control, minimizing the number of circuits and switch contacts that the signal must pass through.
The L-430's rear panel contains, together with the standard input and output jacks (gold-plated for the phono input), large heavy-duty insulated binding posts for speaker connections and separate preamp-out main-amp-in jacks. These are normally connected via a slide switch but can be separated by that switch for connection of a signal-processing accessory (such as a speaker equalizer) between the preamp and power amp. There are also two switched a.c. outlets and one unswitched one on the rear.
The Luxman L-430 is supplied in a black metal cabinet, and its front panel is attractively finished in pale satin gold with matching knobs and buttons. The control layout is well thought-out, with the many pushbuttons grouped according to function. The unit is about 7-3/4 inches wide, 16-3/4 inches deep, and 5-1/4 inches high. It weighs about 30 pounds. Price: $529.95.
Preconditioning the amplifier for one hour at one-third rated power resulted in a rather warm exterior, and some parts of the top plate were too hot to touch comfortably. However, it did not become significantly warmer during our testing, and in use it became only moderately warm.
The L-430 is specifically rated for driving 8-ohm loads, and markings near its speaker terminals make it plain that the total load impedance should not be less than 4 ohms. Our clipping-power tests confirmed that the amplifier has the limited current-output capability that these restrictions imply. The maximum continuous power output into 8-ohm loads was 112.5 watts per channel, for a clipping headroom of 0.5 dB. Although we were able to develop about 120 watts into 4-ohm loads, the output waveform was rounded (rather than sharply clipped). When driving 2 ohms, this effect was even more pronounced, a slight rounding appearing at power outputs as low as 25 watts and gradually becoming more obvious as the power was increased. Eventually the amplifier's current-limiting protection circuits created a large notch in the waveform (this also happened when we drove 4-ohm loads). We decided that 50 watts was the maximum reasonably undistorted output that the L-430 could deliver into 2 ohms. The amplifier's protection system shuts it off with a relay in the event of a major overload or output short circuit and resets automatically a couple of seconds after the overload is removed.
Dynamic-power output (tone-burst) measurements indicated that the L-430 has an excellent reserve power capability, developing 156 watts into 8-ohm loads (for a dynamic headroom of 1.93 dB). With 4- and 2-ohm loads, the dynamic power appeared to be slightly less than the continuous clipping-power output (this could be due to differences in the measurement criteria during tone-burst testing).
Although the bass tone control had a fairly conventional characteristic, with a moderate range and a sliding turnover frequency, the treble control seemed to do little more than vary the gain slightly over a frequency range of several octaves; only near its maximum boost or cut settings was there a significant effect on the frequency response. The loudness compensation (which Luxman calls "low boost") boosts only the lower frequencies.
The RIAA phono equalization was extremely accurate. However, the phono-input termination for moving-magnet cartridges had a relatively high capacitance. Even when using the L-430 with low-capacitance turntable cables, it would be advisable to use a cartridge designed to operate into a load of 400 pF or so. The amplifier was stable with reactive simulated speaker loads, and its slew factor exceeded our measurement limit of 25.
Comparing the measured performance of the Luxman L-430 to its printed specifications, it is clear that the amplifier is honestly rated and easily meets or surpasses all significant specifications. Furthermore, those specifications define a very good amplifier, with ample power for most needs, extremely low distortion and noise levels, and considerable operating flexibility.
Indeed, in most respects it would be hard to criticize the electrical performance or features of the L-430.
Also, as might be expected, the amplifier sounded fine with either MM or MC phono cartridges or a tuner input. We should point out however, that the speakers available to us at the time had what might be called "easy" impedance characteristics, with a minimum impedance of at least 5 ohms, and thus did not activate the amplifier's current-limiting circuits. We would not recommend using the L-430 with speakers whose impedance drops to 3 ohms or less at some frequencies.
The L-430's virtues are undeniable, but we were puzzled by a few of its features. We could find little value in the tone controls, for example, but quite possibly someone else would react differently to their performance. The filters, both low- and high-cut, were more gradual in their effects than we would like (although this amplifier is by no means unique in that respect).
We would have expected the moving-coil cartridge-impedance button to be on the rear apron rather than the front panel, since it is not exactly an everyday operating control. We would have preferred to have the more useful signal processor switch on the front instead.
We hasten to add, however, that the location of a button or two does not alter an amplifier's electrical performance. And the performance of the L-430 was first-rate.