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Product Description

Convergent Audio Technology SL-1 Ultimate Preamplifier

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CAT's philosophy is to design our products to neither add to,nor detract from, the music. We never attempt to cover up a design problem with another problem, nor do we try to introduce a supposedly complementary problem to "synergise" with it. Two wrongs do not make a right. Only the eradication of the problem is correct.

The SL1 Ultimate is the product of relentless refinement to the original SL1 introduced in 1985. We have identified and eliminated every electronic artifact. Rather than attempting to "synergise" with badly flawed systems, this preamplifier is designed to allow superior systems to reach their fullest potential. The SL1 Ultimate also makes the perfect first step toward assembling such a system. Available with or without Phono Stage.


External Power Supply Chassis contains the transformer's magnetic field eliminating it as a source of hum. Rectification, Initial Regulation, and Noise Filtering are all performed in the EPS thereby delivering Pure Quiet DC Power into the main chassis eliminating the grain and dryness associated with noise intermodulation.

Three Independent Fully Regulated Filament Supplies eliminate the dynamic compression caused by filament to filament crosstalk. These supplies are also noise filtered.

Slow Filament Power-Up extends tube life greatly. Quadruple Cascaded Audio Power Supply combines twenty two zero-feedback regulators with over thirty energy storage and bypass capacitors for unequaled dynamic life, soundstage precision and musicality.

Isolation Transformer eliminates entry of Radio Frequency noise through the AC power line yielding greater benefits than any of the expensive add-on power line conditioners without any of their sonic shortcomings.


Pure Vacuum Tube Circuitry for vibrant and natural music. Extraordinarily Quiet High Gain Phono Amp (Optional) accommodates both high and low output cartridges.

Fastest Tube Preamplifier, without any of the high frequency circuit-induced edginess which slower preamps frequently substitute for real speed. This speed is maintained even into long runs of cable.

Lowest Open Loop Distortion of any preamp yields unforced detail and resolution which must be heard to be believed.

Low Feedback Ratios eliminate the aggressiveness of high feedback designs and yet still maintains correct focus.

Matched Output Impedance snubs reflections on interconnects quickly, yielding exquisitely lucid midvange and treble.


Very Strong Steel Chassis with anti-RFI plating ensures hum and RF free operating environment for the circuits.

Damping Material lines both chassis to stop mechanical resonances which would otherwise modulate the electric fields in the preamp.

Mechanical Isolation from floor vibrations provided by high loss viscoelastic feet.


Exotic Low Loss Circuit Board Material combines the transparency of hard wiring with the low resonant signature and musicality of a circuit board.

Balance and Volume Controls are military grade rotary switches with solid silver contacts wired with precision resistors. CAT Manufactured RIAA Capacitors use a unique dielectric with several times lower loss than any other dielectric including TFE Teflon.

The Best Sounding Precision Resistors are used everywhere for the best resolution and minimum unit to unit variability. CAT Coupling Capacitors are made to our specifications and are better than any other audiophile grade capacitor. CAT Audio Wire uses ultra pure, soft annealled copper and super low loss insulation.

Rhodium/Gold jacks for superior connection. Silver Solder used for best electrical connection. Custom Designed Hermetically Sealed Switches.


Front Panel Muting Switch.

Automatic Mute at turn on and turn off.

Record/Normal Front Panel Switch eliminates the non-linear load of the turned off tape deck when in Normal and provides uncompromised recording quality when in Record.

Extra Set of Main Output jacks for special audiophile setups. LOAD Jack allows changing MC cartridge loading while listening to music.

CD and A/V Volume Control Tapers available.



Gain (@lkHz): Line 26 dB, Phono 47 dB

1HF phono input sensitivity: 0.12 my

Gain Tracking: Line.05 dB, Phono.05 dB

Cartridge selection: We suggest .25 and higher, please keep in mind that the lower the output the quieter your tubes should be.

Frequency Response: Line 0.1Hz to 600kHz +0,-3 dB (rise time 0.6 usec) Phono RIAA 20Hz to 20kHz +/- 0.1dB




Harmonic Distortion (@ 1 volt): Line < .0005%, Phono < .001% Slew Rate: Line 15 volts/usec, Phono 10 volts/usec

Maximum Output (@1 kHz): Line 50 volts rms, Phono 50 volts rms Input Overload: Line 100 volts rms, Phono 250 my rms @ 1 kHz Noise: Line 112 dBA below 2 volt output

Phono 96 dBA below 10 my input

Separation: Line greater than 90 dB, Phono greater than 90 dB Input Impedance: Line 50 kohms, 20 pf

Phono 47.5 kohms, 180 pf (user adjustable) Output Impedance: 100 ohms

Maximum Load: Line: under 4000 pf, over 5000 ohms

Dimensions: Main Chassis - 19.0" x 5.24" x 12.2" Power Supply - 12.2" x 4.0" x 6.0"



Power Requirements: 120v, 60Hz, 80 watts (export

Weight: Net 641bs., Ship 701bs.