Audio Research SP11

 The SP11 is a hybrid unit, utilizing both vacuum tubes and FETs (Fiel Effect Transistors). It is not intended that this product should somehow continue the controversy of "vacuum tubes" vs. "solid-state". Rather, in keeping wit Audio Research's design philosophy of advancing the state-of-the-art., each type of device is used where it performs best.

One important result, aside from the dramatically improved quality of sound reproduction, is the use of only six vacuum tubes - tubes which need not be selected low-noise types. A significantly longer time between tube replacement is also expected.

As a last word, this preamplifier may well change your thinking about music reproduction. Because it is so incredibly "open" sounding, much information not previously sudible is available, providing new insight and enjoyment from many sound sources. To be appreciated, the SP11 preamplifier must be personally experienced; it cannot otherwise be adequately related.

 Operational Features:

Automatic warmup, brown-out power-line interruption muting and manual muting at all preamplifier outputs, with new shunt circuitry.

Subsonic phono filter with 6 dB /oct rolloff (to eliminate ringing) with transition to 12 dB/octave.

Bypass switch for use with "audiophile quality" program material.

Absolute phase switch for main outputs, plus unswitched inverting and non-inverting outputs.

Full tape functions; two inputs, two recording outputs, plus tape copy and tape monitor functions.

Input/output connectors have heavy gold plating and connect "ground" before "hot".

Level set control in addition to normal gain control. Allows essentially unlimited input signal range while preserving optimum gain control usage.

Toroid power transformer for low mechanical noise and low external magnetic field.

 In Octobr of 1985, Audio Research Corporation introduced the SP11 preamplifier. During the first year, our introductory claim of "a new reference standard" has been confirmed by reviewer after reviewer throughout the Free World.. It is improbable that any audio product, including previous Audio research products, has ever received such unanimous acclaim. We believe that once you hear the SP11 reproduce music, you will find that acclaim justified.

Specifications

Frequency Response:

High Level Input :  0,2 Hz to 100 kHz ±1 dB (-3 dB below 0,1 Hz and above 200 kHz)

Phono Input:  20 Hz to 40 kHz ±2 dB of RIAA (±1 dB of RIAA, 1,0 Hz to 100 kHz)

Harmonic Distortion:  less than 0,005% at 2 V RMS output, 5 Hz to 20 kHz (Typically less than 0,001% at midband, phono or line input)

Intermodulation Distortion:  less than 0,003% at 2 V RMS output

Gain (aat 1 kHz , bypass mode):

Phono Input to Tape Output :  46 dB (0,2V output from 1mV input)

Phono Input to Main Output :  75 dB (0,175 mV input for 1 V output)

High Level Input to Main Output :  29 dB (36 mV input for 1 V output)

Inputs:  Phono, Tuner, CD, Video, Spare, Tape 1, Tape 2,

Outputs:  Tape 1, Tape 2, Main 1, Main 2, Direct, Invert

Filter:  25 Hz Hi-pass phono subsonic 6 dB/octave rolloff (to eliminate ringing) with transition to 12 dB/octave at 10 Hz. Front panel switchable, phono only

Controls:  Gain, level (to set gain Range), balance, Mode, Input, Impedance

Switches: Tape Monitor, Copy, Tape 1/2, Tape 1 to 2/2 to 1, Mute, Invert Phase,Bypass, Filter

Input Impedance:

Phono :  47 k Ω, 100, 30, 10, 3 Ω (front panel selectable)

Phono Input Capacitance:  150 pF at 10 kHz

High Level:  20 k Ω or higher, depending on switch functions

Maximum Inputs Level Undistorted:

Phono :  350 mV RMS at 1 kHz, 1200 mV RMS at 10 kHz (0,1 second maximum duration, 6 dB less if continuous)

High Level :  25 Volts RMS

Output Impedance:  250 Ω main, direct, invert outputs, 500 Ω tape output. Recommended load 60 k Ω and 100 pF (25 k Ω minimum, 1000 pF maximum)

Rated Output:  2V RMS 1 Hz to 100 kHz main, direct, invert outputs (Maximum 80 V RMS output at 0,2% T.H.D. at 1 kHz into 60 k Ω load with 2,85 V RMS high level input)

Phase:

Tape Outputs, Direct Output;  Non-inverting

Invert Output :  Inverting

Main Outputs :  selectable non-inverting or inverting. All outputs may be used simultaneously.

Noise (IHF Weighted, shorted input):

Output (Gain down) :  6 µV (110 dB below rated output)

Input High Level) :  3 µV equivalent input (110 dB below 1 V input)

Phono :  0,15 µV equivalent input (76 dB below 1 mV input)

Tube Complement (Hybrid FET/Tube Audio Circuit, Solid-State Power Supply):  6 - 6DJ8/ECC88

Power Requirements:  95 - 135 V AC 60 Hz (Export 190 - 270 v AC 50/60 Hz)

Power Consumption:  130 watts maximum

Dimensions (W x H x D) Each Chassis, EIA Rack panel Mounting:

480 x 134 x 260 mm (19" x 5,25" x 10,25")

Weight Net:

SP11 :  6,4 kg (14 lbs)

SP11PS :  6,8 kg (15 lbs)