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| CONVERGENT
AUDIO TECHNOLOGY |
| SL-1
Signature Pre-Amplifier |
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A
masterpiece is completed with the Signature
The SL-1 has
been acclaimed by audio purists and music lovers worldwide as the
finest preamplifier available since its introduction seven years
ago.
Continued
refinement of the power supply and components has pushed the sophisticated
and innovative pure vacuum tube audio circuitry ever closer to the
realization of its fullest potential.
Now with the
introduction of the SL-1 Signature, the realization is complete.
The resulting
sound is everything the people at Convergent Audio Technology envisioned
seven years ago ….
Listen to
a masterpiece.
SPECIFICATIONS
Specs tell
little about a component's sound quality, and this is especially
true with audio electronics.
Any good engineer
can design an amplifier with excellent specs. In fact that is almost
always his sole design goal. Good specs can be achieved without
improving, and sometimes at the expense of, the sound quality. CAT
knows of no standard spec which was established with the use of
listening tests to determine just how relevant, that spec really
is. Specifications have become a numbers game to play with the consumer.
Despite CAT's
disdain of specification as an absolute indicator of sound quality,
they believe strongly in using measurements (of numerous and usually
non-standard types) as a design tool, coupled with listening tests,
to enable them to determine which parameters are important and how
to improve them. Fortunately, for the spec lover in all of us, the
specifications of the SL-1 all range from excellent to spectacular.
Some of these specs could have been even better at the expense of
sound quality, but this would be inconsistent with CAT's slogan
"Technology Serving Music." |
| Gain (@1 kHz) |
Line 26 dB
Phono 46 dB
Total 72 dB results on IHF phono input sensitivity of 0.12 mv |
| Gain Tracking |
Line 0.05 dB
Phone 0.05 dB |
| Frequency Response |
Line 0.1 hz to 600 khz = 0, -3dB
(rise time 0.6 microsec.)
Phono RIAA +/- 0.1 dB 20 hz to 20 khz |
| Harmonic Distortion
(@ 1 volt) |
Line less than 0.0005%
Phono less than 0.001% |
| Slew Rate |
Line 16 volts/usec
Phono 10 volts/usec |
| Maximum Output (@
1 khz) |
Line 50 volts rms
Phone 50 volts rms |
| Input Overload |
Line 100 volts rms
Phono 250 mv rms at 1 khz |
| Noise |
Line 90 dba below 1 volt output
Phono 96 dba below 10 mv input |
| Separation |
Line greater than 90 dB
Phono greater than 90 dB |
| Input Impedance |
Line 50 kohms, 20 pf
Phone 47.5 kohms, 180 pf (user adjustable) |
| Output Impedance |
Line 75 ohms
Phone 75 ohms |
| Maximum Load |
Line under 4000 pf, over 5000
ohms
Phono under 4000 pf, over 10000 ohms |
| Dimensions |
Main chassis - 19.0" x 5.24"
x 12.2"
(standard rack mount faceplate)
Power Supply - 12.2" x 4.0" x 6.0"
(connected by fixed cable) |
| Weight |
Net 54 lbs
Ship 60 lbs |
| Power Requirements |
120 v, 60 hz, 50 watts
export version available |
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Separately
grounded nickel plated steel external power supply chassis
contains the transformer's magnetic field, eliminating it
as a source of hum. |
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Pure
DC voltages delivered into the main chassis. Rectification
and initial regulation are done in the external power supply. |
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Isolation
Transformer eliminates entry of AC power line noise into the
preamp yielding greater benefits than any of the expensive
add-on power conditioners. |
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Three
independent fully regulated filament supplies eliminate dynamic
compression caused by filament to filament crosstalk. |
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Slow
filament power-up greatly extends vacuum tubes life to several
years. |
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Quadruple
cascaded audio power supply with nineteen time compensated
zero-feedback MOSFET sub-regulators, one for each stage of
each channel, provides unequalled dynamic contrasts and soundstage
realism. |
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Pure
vacuum tube audio circuitry produces harmonically natural
gain-free music. |
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Extraordinarily
quiet high gain phono amp accommodates both MM and low output
MC cartridges without the need for an external step up device. |
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The
fastest tube preamp, faster than the fastest transistor units,
and without their edginess. |
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The
lowest openloop distortion of any preamp yields a level of
resolution which must be heard to be believed. |
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Low
feedback ratios eliminate the radio frequency resonances,
and attendant hardness, of high feedback designs and yet gives
excellent channel to channel gain matching. |
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Matched
output impedance snubs reflections from inter-connects yielding
exquisitely lucid highs. |
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Balance
and Volume controls are high reliability military grade solid
silver contact rotary switches wired with precision resistors
providing unprecedented channel gain tracking while eliminating
both the highly non-linear resistance element of conventional
"pots" and the poor contact on the wiper on the
resistance element. |
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CAT
manufactured RIAA capacitors use a unique dielectric with
several times lower loss than any other capacitor dielectric
including TFE. |
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The
best sounding precision resistors are used everywhere for
the best resolution, lowest noise and minimum unit to unit
variability. |
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Premium
audio wire used for audio signal to eliminate wiring as a
consideration in the sound quality. |
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Rhodium/Gold
jacks provide audibly superior connection over any other jack. |
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Silver
solder used for the best electrical connection. |
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Custom
designed hermetically sealed switches used for best sound
quality. |
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Very
heavy steel chassis with anti-RFI plating ensures hum and
RF free operating environment for circuits. |
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Damping
material lines chassis to stop mechanical resonances which
would otherwise modulate the electric fields, and hence the
signal, in the preamp. |
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Mechanical
isolation from floor vibration provided by high loss viscoelastic
feet. |
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Front
panel muting switch. |
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Automatic
mute engaged at turn-off and 30 seconds after turn-on. |
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Front
panel LED indicates when unit is operational. |
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"Record/Normal"
front panel switch eliminates the non-linear load of the turned
off tape deck when in "Normal" and provides full
fidelity taping when in "Record." |
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Extra
set of MAIN OUT jacks useful for special audiophile setups. |
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"Load"
jacks on back allow channeling MC cartridge load resistance
plugs (supplied) while playing music. |
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"What
is best? This is always very difficult to answer as nothing is perfect
and everything is personal. We have been working with the C.A.T
for some years now and it still takes the top place for us even
though there are many others that are very good and close on its
heels. If you have had a C.A.T. in your system for some considerable
time then it is very difficult to live without it. This is because
it seems to do one thing better than any others do -- it plays music.
Many of its rivals some of which are very, very good like the B.A.T
or the Woodside both of which we are very keen on and recommend
thoroughly, may in some cases have some attributes that beat the
C.A.T on a particular point but for us the C.A.T gives the feeling
of total reality especially as far as the sound stage goes and on
live music its transparency and uncanny way of bringing life to
the music keeps it as our No. 1 choice. The JL1 amplifiers have
over the last year or two joined the pre-amp and these too are beginning
to enjoy the same reputation. A full C.A.T set up is still a benchmark
and one that will hold the candle in your system for many years
to come." |
| A
Review by Marc Mickelson - Soundstage March 1996 |
I've
owned a Convergent Audio Technology SL-1 Signature preamp
for about a year, and aside from problems with residual
hiss--a byproduct of its high line-stage gain--I love what
I hear. The CAT has the unique ability to sound highly transparent
and utterly musical at the same time?from my experience,
a rare feat. It's also built like no other preamp, 60 pounds
of heavy steel with internal damping material and an outboard
power supply. I've always felt I've gotten my considerable
money's worth with the CAT.
Mr.
CAT, Ken Stevens, is another matter: he's priceless, an
interesting and opinionated man who is constantly tweaking
his wunderkind. This ensures that his preamp will always
sound the best it can, but all his work is a problem for
those of us who buy a CAT only to find that it's changed
a month later. More than any other piece of equipment, the
CAT preamp is tied to its serial number. Keep this in mind
if you look for a used unit.
Although
the CAT preamp is in constant evolution, only recently has
its model designation changed, to (big breath) the "SL-1
Signature Mk II." My CAT is one year old; it has the most
obvious improvements that have been worked in since the
CAT Signature's debut: heavier bottom plate, and a new umbilical
from the power supply to the preamp itself. I've recently
had the chance to compare a new Mk II with my original unit,
and from a purely visual standpoint, the differences are
slight. The circuit boards in the power supplies have all
the same markings, but the board in the Mk II seems to be
made of a different material and is perhaps thicker. In
addition, the one bright-blue Phillips capacitor in the
power supply has been replaced with an IC cap, the same
brand used liberally throughout the preamp. I couldn't spy
any obvious differences to the board or components in the
preamp itself, but I did notice that the wiring in my older
unit is much neater, with less slack and more calculated
use of wire ties. This, of course, is due to manufacturing
variation--if only sloppy wiring were all it took to make
a great piece of equipment.
Sound:
very, very close. The CAT Signature Mk II seemed to have
marginally more extended bass and was a little quieter,
but these differences could be attributable to its new tubes,
especially the 12 AU7s in the linestage. These are the most
prickly pair in the CAT and can affect the sound in a profound
way. Convergent is now using "German RFT" (what Ken Stevens
called them) 12AU7s; if you have an older CAT, you should
strongly consider popping for a new factory tube set. The
last I heard, Convergent was not going to offer the Mk II
changes as upgrades to older units, but by buying new tubes,
you may be getting the bulk of the Mk II upgrade in the
process. Oh, I did forget to mention the most considerable
difference between old and new CATs: a $1000 increase in
price. Who says that high-end equipment isn't an investment?
Marc
Mickelson |
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