Solid State Preamp Reviews

The Model 34 preamplifier is the component from English manufacturer Quad that will disenchant perfectionists, partly because of its obvious pandering to connoisseurs of old and sometimes lousy-sounding records, and partly because of its sound.

This solid-state design is supplied with a built-in moving-magnet cartridge preamplifier, and a moving-coil preamp is included with it for (easy) installation by the user if desired. (Remove two screws, pull out the old module, plug in the new one and replace the screws. The job takes about 3 minutes.) The MC preamp supplied is for 20 microvolt-output cartridges—contrary to the instruction booklet's statement that the supplied one is the 100µV version. Modules having a rated input level of 100 or 400µV are available as extra-cost options.

The 34 has sensitivity characteristics complementary to those of the 405 power amplifier. With a rated output of 500mV, it will be unable to drive most US and Japanese power amps to full output, and this time there is no simple solution comparable to the one referred to in my review of the 405 amplifier, other than to use it only with a European power amplifier such as the Quad 405. Its phono inputs are RCA sockets, but all other connections to and from the preamplifier are via DIN receptacles. Adaptors are provided for the Tape connections and one high-level input, but additional sources will require additional adaptors (which most audio dealers carrying Quad, Creek, or B&O components should have in stock).

The Aux input, incidentally, can be used as either an input or an output (by inserting internal circuit-board jumpers and using a 4-conductor Tape adaptor cable), but not simultaneously. Since the inputs and outputs are common to one another and not the two sides of an interruptible loop, they can be used either to feed input signal to a second recorder or to listen to its playback, but attempts to do both at once will connect the recorder's outputs to its inputs and may cause a destructive feedback condition.

The 34 has three pushbuttons on it for selection of HF filtering. Two of them provide 6dB/octave attenuation, with –3dB points of 10kHz and 7kHz, respectively. (They cannot be depressed simultaneously.) The third switch increases the sharpness at which the first two roll-off the high end. The effect of these is not subtle, but neither is their efficacy in eliminating crud and distortion.

Also unsubtle are the actions of the bass and tilt controls, which are incremented in 2dB steps. The bass Lift (boost) acts like a Baxandall control, with the turnover frequency moving upwards as the boost is increased. The bass Step function is unusual in that, instead of rolling off the low end (thus progressively attenuating the deeper bass), this one depresses the entire bass range by about 6dB relative to the upper ranges, introducing a shelf into the low-end response. The amount of shelving remains constant, but the control varies the frequency at which the shelf cuts in (100, 170 or 200Hz). This varies the low-end balance without affecting its low-end limit.

The Tilt control, which as far as I know is unique to Quad's preamps, does exactly what its name implies: it rotates most of the audio-range frequency response around an 800Hz axis, so as to change the overall balance of the sound from warm to cool without affecting either the apparent volume or the "color" of the sound. (Fig.1 shows Quad's curves for this control, fig.2 shows the measured effects for this cpomtrol and for the filters and phono stage.) Each increment changes the 100Hz level by 1dB in the direction opposite to the 10kHz level, providing a 2dB bass/treble change.

Because of the ear's tendency to latch on to the average signal level over a wide range as the "normal" level, the subjective effect of this control is actually rather different from what is shown in the curves. The frequency extremes, although actually "flat" in terms of the horizontal, sound as though they curved in a direction opposite to the middle-range tilt. Thus, the curve showing a 3dB rise at 100Hz and below sounds as if the low end rolled off below about 50Hz and the high end tipped up above 12kHz. This is advantageous, because it allows a significant amount of adjustment of the overall balance of a recording without undue detriment to its frequency extremes.

What all this adds up to is a preamp/control unit far better able than most to correct for many of the worst and most commonly encountered sonic flaws in recordings. The "lack of subtlety" in the action of the controls is no liability whatsoever when the problems they are correcting for are so gross.

Sound quality
Aha, but what does the 34 sound like? And there's the rub. It is colored. Not seriously, but significantly. The much-overused term "velvet fog" is appropriate here, for this is a rather forgiving preamplifier, tending more to errors of omission than commission. Inner detail is not very good, its low end is a trifle woolly and does not shake the floor (even when it should), and its high end seems to round off the burrs and sharp edges of the music much as did the early Dynaco tubed preamplifiers. It does not, however, share with those tubed units their edgy brightness. The sound is, if anything, too suave and rich, always eminently listenable but never palpably real.

As an isolated component, I find this just too chocolatey-sweet for my taste. But it does mate well with the rest of Quad's system, the ESL-63 speakers and the 405 power amplifier.

Incidentally, Quad's instruction booklet for the 34 preamplifier makes a very good point about listening level, asserting that for a given recording there is only one correct volume setting. I agree generally, but with qualifications. The "correct" setting is where the perceived volume of the instruments "agrees" with their apparent distance from the listener, which makes perfect sense when the recording was done with "purist" microphone technique—two, or at most three, microphones for pickup of the entire group.

But many multimiked recordings produce an ambiguous perspective, where instruments sound very close yet far away—London is is a master of this so-called near-far sound—and for these the "correct" volume setting is far less ordained. In either case, propoer volume adjustment requires a certain familiarity with the sound of the real thing, which is something audiophiles as a group cannot always bring to a listening session. Some recordings, such as the ones Harry James has done on Sheffield Lab, demand very high playback levels in order to sound realistic; for these kinds of recordings the Quad ESL-63 speakers are simply not appropriate.

Many audiophiles like to play all recordings at very high level, sometimes because the loudspeakers are "slow" and seem to prevent the sound from escaping from them, sometimes simply out of a wild and crazy desire to feel the music. And hard-rock enthusiasts are notorious for playing their systems at ear-shattering levels for no better reason than "Because" (footnote 1). The Quad ESL-63s are not designed for that kind of abuse, and although they may not be damaged by it (unless continued for some time), they just won't deliver that much SPL. They are designed primarily for the classical-music listener who intends to listen at volumes one would encounter in a typical (perhaps even distant) concert hall seat.—J. Gordon Holt

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Footnote 1: JGH himself is not totally immune to this temptation.—Larry Archibald