AT THE TIME WHEN HIGH AUDIO BEGAN, ONLY
ANALOGUE SOURCE MATERIAL WAS AVAILABLE, and vinyl dominated the audio
scene. The LP does not stand up very well by any obvious measurement
criteria except upper frequency limit, but it sounds, at its best,
remarkably good. It was this discrepancy that led high end audio away
from trying to evaluate sound quality via measurement and even from
trying to correlate the two.
Digital in contrast is naturally numerical interpretations spring from
it automatically: Dynamic range = 6 x number of bits; maximum
frequency = -sampling rate, and so on. Numbers have crept in the High
End door, sneaking in on digital's shadow.
The Bryston 3B-ST amplifier is an interesting instance - it offers
both superb sound quality and superb performance by numeric measures.
Now I surely do not mean to suggest that the Bryston was designed by
numerical measurement criteria alone. The Bryston people listen very
carefully and also have collected listening impressions from their
dealers and customers for many years. But they seem to have
established over years of listening and measuring, a way to connect
the two in practice. And to some extent, the 3B-ST represents a
successful attempt to live up to the numerical criteria implied by
digital standards, while at the same time offering truly remarkable
sound quality from either digital or analogue sources. It is a
champion in both worlds, the technical and the musical world of
listening.
In the context of the attention now being
paid to new digital standards, and the descriptions of the
significance of numbers of bits, it seems appropriate to translate
usual ideas of amplifier performance - technical measurements and,
when possible, listening impressions - into digital terms. In this
situation, 6 dB is 1 bit. For example, 16 bits correspond to 96dB of
dynamic range or signal to noise ratio. (Actually, 1 bit is equivalent
to slightly more than 6dB, but 6dB is a good enough approximation for
present purposes.)
To clarify this kind of conversion to digital, let's think about noise
first. The 3B-ST is extraordinarily quiet. Its noise level is circa
115 dB below full output. (Exact figures depend on what kind of
weighting is used.) This means that the 3B-ST can cover the whole
dynamic range of CD with ease. Indeed, its signal-to-noise ratio is
equivalent to 19 bits plus (6 x 19 = 114). In listening terms, this
means a silent "black" background.
Now let us take distortion. Distortion figures (THD + noise) for the
38 ST run on the order of .002% or less of the signal at nearly the
rated output of the amplifier. This translates to distortion about 94
dB or more below signal. (1% = 1/100 of signal=-40 dB; 1%=1/1000 =-60
dB, the figure dropping by 20 because power in dB is proportional to
voltage squared while percent distortion is given in voltages, not
power.) Once again, the full range of CD is covered, or essentially
so, This is truly extraordinary performance, matched by few amplifiers.
For comparison's sake, suppose an amplifier has 1% distortion + noise.
This is 40 dB down from signal. But that is only between 6 and 7 bits
down! So if a signal is at the peak level, 16 bits, then the error is
already affecting between 9 and 10 bits. In effect, the resolution is
enormously reduced. (No one thinks much of a CD player that drops 9
bits!) Similarly, 0.1% distortion + noise, 60 dB down, is 10 bits
down, so at the 16 bit level, 6 bits are turned into garbage.
This might seem at first sight to an
exercise in dB arithmetic. But listening to the 3B-ST, one begins to
think that it is not idle at all. The amp is unusually transparent. So
much so that prolonged listening with high quality digital sources has
given me a new appreciation of what can be accomplished in a certain
kind of crystalline clarity, a virtually complete transmission of
signal. Granted the 3B-ST seems to have a slightly more prominent top
end than most amplifiers. But the clarity is more than a
frequency-response effect, or so it seems to me. Indeed, even when I
used a Sigtech "target curve" to roll the top down somewhat, the
clarity remained.
Of course, interpreting listening
experience in terms of technical criteria is risky. Moreover, it is
hardly clear how measured electronic performance, which invariably
exceeds speaker performance in measured terms by such a large margin,
is reflected in the listening experience at all. But somehow the
Bryston 3B-ST together with, for instance, the exceptional Harbeth
Monitor 40 speakers with (in particular) their remarkable upper
frequency performance, gave a virtually unprecedented access to fine
detail of sound. When the Sigtech prodded the system the last small
steps to neutrality, the result was a remarkable insight into
recordings, a feeling that the sonic window had become cleaner than
almost ever before.
There is a school of thought that finds
kind of nearly absolute transparency not entirely consonant with
musical experience. This was made explicit some years ago by Jean
Higara, dean of French audio critics (and designer of a line of well
thought-of tube amps), who claimed that the low-order harmonic
distortion of tube amplifiers was not just benign but actually
beneficial that it masked disagreeable higher-order distortions in the
recording. (This refers to power amps only. Low-level tube circuitry
can be very low in distortion.) In my review this has been extended,
without being made so explicit, to noise masking as well. Some people
seem to have come to hear the noise-masked sound as natural and
musical. And of course the fact is that most recordings, especially
older recordings, were consciously or not, balanced and miked for
playback in a masked playback environment, since until recently no
other environment was possible. (I refer now to electronics; the old
Quads, whatever their other limitations, were and are quite an
unmasking speaker.)
Times change. As it happens, Bryston
amplification is widely used in serious professional monitoring. To
take a rardom example, I noted shortly before writing this review that
the Chesky recording of David Chesky's Three Psalms for String
Orchestra was monitored with Bryston amplifiers. Perhaps not
coincidentally, this recording sounded remarkably pure and beautifu1
with the 3B-ST. Indeed most recordings showed their best. Certainly
one could observe their limitations; and, sometimes in rather
startling ways, problems in the music itself were made apparent that
were in other circumstances not so obvious. For instance, slight
irregularities in piano voicing, notes with a bit of excess "twang" or
hammer tone, were unusually detectable on close-to piano recordings,
and so on. But on the whole, being able to hear so far into the
recordings was much to their musical advantage. The clarity was
hypnotic in musical terms.
I believe a new general picture is
emerging here. Audio until recently was a matter of distortion and
noise masking other distortion and noise. In the absence of a source
medium that even began to approach the signal-to-noise performance of
the ear, the perception of quality in p1ayback was inevitably a matter
of revealing a lot but not too much. We instinctively sought
components that would reveal the musical wheat but hide the noise and
distortion chaff. Of course, this was going on at a very subtle level,
but going on it nonetheless was.
In this context, digital, deeply flawed
though it was in early execution, eventually improved to the point
that it became a salutary shock. In spite of the bandlimiting of the
CD standard, it otherwise offered a far lower level of noise and
distortion than vinyl. And it thus called for amplification that would
match its unmasking capabilities, both in low noise and low distortion.
At the same time, it demanded, with its uncompromising high
frequencies, high-frequency transducers of the highest possible
quality. Without complete success in all aspects the digital source
itself, the amplification, and the speakers, especially to the top end
the result could be musically less satisfying than the old systems,
involving complementary maskings, which had also developed a great
degree of refinement.
The 3B ST and Bryston BP-25 preamp with
the Monitor 40s Sigteched (with the Sigtech also functioning as a
D-to-A converter, and on occasion with the Sigtech's digital output
feeding the Morch D-to-A), and especially in the context of the
extraordinary ScanSpeak Excel tweeter as implemented in the Monitor
40s, signa1 for me a new era. They provide a system in which the full
theoretical potential of CD digital is nearly revealed. And this
potential comes quite close to meeting the capabilities of the ear
itself in many respects. The new digital standards will come even
closer, but really well-executed CD is already surprisingly good.
This does not mean that musical realism is
complete. Stereo itself has limitations, as do microphones. And even
exceptional speakers, even combined with the Sigtech system, do not
attain the low distortion, low noise, and smoothness of response of
the amplification. But in this total system, I do find a sense of
clarity of presentation without harshness or edginess and a purity
that is an unending source of musical satisfaction.
There are many amplifiers that offer
distortion nominally well below the supposed thresholds of audibility
of distortions of various kinds. But the Bryston 3B-ST made me wonder
it these supposed thresholds have not been set far too high. The 3B-ST
simply sounds cleaner and purer and more nearly devoid of grain and
noise, whether signal related or otherwise than almost any other
amplifier I've heard.
For all its virtues, the 3B-ST is not
universal in applicability. It is not seemingly very happy with loads
below 2 ohms, and with difficult loads and/or low-sensitivity speakers,
it can complain. (The original Carver Amazings had it crying for mercy
when I turned it up.) The 3B-ST is a rapier, not a saber. Bryston has
bigger amps (or one can run the 3B-ST in bridged mode) when more
muscle is needed.
I am well aware
that some people will look at the 3B-ST and say, oh, just another
solid-state device of moderate power and extended highs. And the 3B-ST
is indeed a fairly unconventional amplifier, as I understand it, as
far as general circuit design goes. But the Bryston people seem to
have managed, by consistent, long-term listening tests and technical
refinements, to have moved to the forefront in the particular way I
have been describing. The 3B-ST is an unpretentious, small black box.
It is not a designer statement, visually. And it is not even very
expensive. But it goes very far in the direction of perfection in
amplification, in transmitting the entirety of its input signal. Built
carefully, it is guaranteed for 20 years. You are likely to want to
keep it that long. When the new digital standards show up and even
with CD reaching its potential, most amplifiers are being left behind.
What use is 20 bits of resolution, or even just all of CDs 16, if your
amplifier has resolution and S/N ratio for only 12? The 3B-ST is up to
the challenge.