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Most people recognise that
hi-fi products need a certain amount of running-in when new, and then
subsequent warming-up before each use, in order to hear the very best
performance available. But if there was ever an inquiry held to study how
essential this process can be, these boxes from GSP Audio could be called
forth as the star witness.
The story actually starts at the very end of last year. After a conversation
with Graham Slee about audio design philosophy, with reference to his select
range of phono amplifiers, I was looking forward to trying one of these
phono amps that have acquired something of a cult following. Like many
bits of British hi-fi before them, they have a 'music first' school of
design - that is, the interesting things happen inside with the
electronics, rather than outside with fancy casework. This will immediately
turn off a percentage of the audience who take pride in the gilding of their
audio lilies.
Conventional wisdom in audio electronics says we
can hear as high as 20kHz, on a good day with a following wind; so quality
hi-fi should reproduce harmonics this high, but not much higher. Any more
bandwidth just invites more noise and distortion into the system.
Consequently most hifi is designed this way (although more people are
recognising that it might be an idea to give a flat response at least as
high as 100kHz; for example, to help ward off phase distortion at the top
end of the traditional passband). Phono stages in particular tend to have
their bandwidth curtailed, often from both directions, as low-cut
filters are introduced to remove infrasonic signal from warped records and
rumbling turntable bearings, while a high-cut filter helps reduce the chance
of picking up Radio Luxembourg as a byproduct of the huge magnification of
quiet pick-up signals.
As you may have guessed from this preamble, Graham Slee doesn't agree with
such traditions.
It's all about slew rates and phase accuracy. To
accurately reproduce an impulsive signal, one that appears very quickly and
disappears as fast, you need a very wide bandwidth channel. And at the low
end, keeping warp filters out also encourages accurate phase. So where most
phono amps restrict gain after, say, 40kHz, the Era Gold and Elevator EXP
take pride in an operational bandwith up into the megahertz.
The Era Gold is a moving-magnet stage, able to take the raw output of an m-m
cartridge and raise it to line-level with the necessary equalisation. There
are no controls or adjustments to make, as it offers just the standard 47k
ohm input for a fixed-coil pick-up. Gain is 41.5dB, meaning it should work
fine with any cartridge in the usual range of output
levels, as high as lOmV. It takes its power from a generous 12W external
transformer, which plugs into the back of the Era from a long bellwire-like
lead.
For moving-coil cartridges, extra gain is needed along with a sympathetic
lower input impedance. This is available by adding a step-up unit, the
Elevator EXP. This serves the same function as a high-grade step-up
transformer, but using solid-state electronics to achieve its goal rather
than inductive windings.
The sound of the original combination of Era Gold/Elevator EXP, after
several months of steady use, was characterised by a very even, consistent
tonal balance, full of timbral colour, and shimmering with pure sweet
treble that seemingly had no bound. There was little exaggeration in the
bass, just low extension, rich but quick. High frequency details
were this combination's strength, being intricately rendered with
uncommon ephemerality - that is, quick to appear and then decay, but not
without a tenacious command of reverb tails as room acoustic details faded
to zero. Strummed acoustic guitar could show the thwack and zing of
transient impact, while ride and hi-hat cymbals insisted that when it
comes to jazz and rock rhythm 'n' timing, we should be paying attention to
more than just the basslines. |
Left-to-right spread was deliciously wide,
giving the impression of full dual-mono architecture, even if LP replay is
acknowledged to have a crosstalk figure of about 30dB, often much lower.
Well-recorded rock drums and their display in believable reality was
certainly one aspect to benefit from the use of this phono amp combo. On
another level, the quietness from the GSP effect was alarming. That's
the quietness of intrinsic background hiss, quietness of groove noise, and
the subjectively low overall impact of record noise. Clicks and pops were
relegated to inconsequence when they appeared.
A lengthy review period was in part reaction to running modifications to the
design, which necessitated another trial of the revised Elevator and Era.
New cases and PCBs alone can rewrite a product's sound, let alone a change
of circuit or components. Thus started another period of running-in of the
new electronics.
Unsurprisingly, the new Era Gold/Elevator EXP sounded akin to the first
sample. Initial differences centred on a drier, less flowing character of
the later boxes, with a loss of the sublime liquid treble quality that was
previously so inviting to the ear. This was replaced with a more 'transistory'
treble, especially on cymbals; and sibilants could be accentuated
on female voice. Where the first sample had stood out as something quite
magical, the new version was more on a par with rivals around the same
price.
A few weeks of continual use later (with thanks
to Keith Martin at Audiophile Candy for loaning an inverse-RIAA equaliser,
indispensable for running-in phono stages), and the replacement Era/Elevator
were slowly catching up with the first samples. Now if was evident that the
latest versions do have a tighter bass quality with perhaps more perceived
LF depth and impact, where the previous generation could border on the
'fruity' at times. With its more accurate bass, steadily improving open
treble, and increasingly holographic soundstaging, the current GSP Era Gold
and Elevator EXP are still settling daily, and drawing closer to the
addictive, valve-like purity of the earlier samples.
With the GSP Audio Era Gold V and Elevator EXP confirmed once again as
something special, it should be remembered that these are more 'enthusiast'
products than, say, a Linn Linto. Where the Linto can be dropped in anywhere
and relied upon for its quiet, fuss-free operation (not to mention, superb
sound quality!), the GSP units need a more tender loving care to behave
correctly.
Two external transformers must be carefully sited - I found some
experimentation here on different surfaces could improve performance - and
their cables carefully dressed, preferably observing 90° angles when
crossing other wires. Tweaking input impedance is essential, with best sound
from an Ortofon Kontrapunkt A found at either 30 or 100 ohm. System wiring,
and local mains, must be clean and free of noise, to help keep pick-up and
RF demodulation at bay.
Finally, there's the issue of run-in and warm-up as
these units need to be left on continuously - and used regularly!
With those practical points in mind, the GSP Audio Era
Gold/Elevator EXP pair rates as one of the finest moving-coil phono stages
I've used and earns a hearty approval for record junkies who want to hear
more of what's really in the vinyl groove.
-
Andrew Harrison |
