Cary Audio Design SLP-308 Specification sheet

SLP-308 Vacuum Tube Stereo

Preamplifier

Operation and Installation Manual

Please read this manual carefully before installing your new SLP-308 into your stereo

system. It contains important set up and installation information as well as safety

warnings regarding AC voltage inside the chassis.

Dear Audiophile Friend:

I would like to thank you personally for buying a Cary Audio SLP-308 preamplifier. I

have spent many hours designing and voicing the SLP-308. You will find many desirable

features on your new preamplifier including a motorized remote volume control, dual

RCA connector outputs, dual output level meters, a 200% duty cycle power

transformer, fully regulated high voltage power supply and fully regulated filament

voltage for the tubes. The high performance motorized volume potentiometer we use

to control the analog input signal level is driven mechanically by a DC motor. All

incoming signals are switched via gold plated relays. The best feature of the SLP-308 is

the sonic presentation. The 12AU7 triode tubes used in the SLP-308 are considered by

many to be some of the very finest sounding dual triode tubes. Please read the

instruction manual so you are familiar with the operation of your new SLP-308.

Thank you once again for your interest in and continued support of Cary Audio Design.

Dennis J. Had

President

SPECIFICATIONS: SLP-308 Stereo Tube Preamplifier

Dimensions: 17 1/8” W x 4 _” H x 14” D (~ 44 cm x 11.4 cm x 35.5 cm)

Weight: 15 lb. ( 6.8 kg)

Circuit: Class A Triode

Frequency Response: 9 Hz - 140 kHz + 0, - 3 dB

THD @ rated output: 0.02% (750 mV rated output, 12 volts maximum)

Input Impedance: 100,000 ohms resistive (100 K W)

Output Impedance: 440 ohms ( 440 W)

Gain: 12 dB

Signal/Noise Level: -88 dB

Resistors: 1 % metal film

Capacitors: Film and foil output caps, 5 micro farad (5 mFd)

Power Transformer: 200% continuous commercial duty cycle

Tubes: 2- 12AU7 dual triodes

Power Supply: Full wave rectification, center-tapped, pi-network with filter choke, fully

regulated

AC Power Requirements: 100 – 130 volts AC / 50-60 Hz at 24 watts

200 – 245 volts AC / 50-60 Hz at 24 watts

Internal Wiring: EE Teflon dielectric Silver wire

Warm-up Time: 5 minutes (1 minute auto mute)

Input and Output Jacks: Gold plated with Teflon dielectric inserts

Duty Cycle: Continuous duty 24 hours per day

This section describes the basic specifications of the SLP-308 at the time of printing. Specifications are

subject to change or improvement without notice or obligation.

FRONT PANEL FEATURES

Power Switch: 2 position toggle switch off/on controls the AC line voltage

Mute: Terminates (quiets) the output, also operated via remote hand set

Input Select: 4 position rotary switch controls relay input switching

Tape Monitor: 2-position toggle switch engages tape loop circuit

Listening Level: Motorized volume control, manual or via remote, with additional

blue indicator LED in the volume knob.

Dual Output Level Meters: These show output level voltage to the power amplifier, 0

dB is equivalent to 0.775 volts output.

On LED: Indicates internal power supply is power up

Operate LED: Indication of time delay release (approximately 1 minute)

Down LED: Lights up red as remote volume is turned to a lower setting.

Up LED: Lights up blue as the remote volume is turned to a higher setting.

REAR APRON FEATURES

AC Connector: Inlet for the detachable AC power cord, standard IEC plug

AC Fuse: !!VERY IMPORTANT!! ONLY USE 1 AMP Slow Blow FUSE

Remote Trigger: Female 2 circuit jack, 12 VDC @ 400 ma., On when power is on.

Dual Preamp Outputs: Connect to inputs of power amp or powered subwoofer

Tape Out: Constant output of selected input signal for recording, independent of

volume control setting.

Tape In: This is the tape monitor selected input. For use with recording devices that

employ a monitor system to hear the actual recorded signal. May also be used as an

additional line input or an input for an equalizer or other signal adapting device.

CD, Aux1, Aux2 and Tuner: These are inputs requiring line level inputs from source

components. These inputs have wide bandwidth, flat frequency response.

INSTALLATION AND UNPACKING

WARNING!

MAKE NO ATTEMPT TO PUT THE SLP-308 PREAMPLIFIER IN SERVICE

WITH THE COVER OFF THE UNIT. CONTACT WITH THE AC

VOLTAGE INSIDE THE SLP-308 CAN BE FATAL!

All our shipping cartons have been especially designed to protect their contents and

special care has been taken to prevent damage under normal conditions. Mishandling

should be evident upon inspection of the shipping container. If damage is found after

visual inspection, do not destroy the evidence. If necessary, document the damage with

photographs and contact the transport carrier immediately.

Carefully remove your new SLP-308 from its packing carton and examine it closely for

signs of shipping damage. It is recommended to save all original packing cartons to

protect your preamplifier should you wish to store it or ship it for after-sales service.

WARRANTY CARD

If you are the original USA purchaser of this preamplifier and purchased it for use within

the United States, you should fill out the enclosed warranty registration card and return

it to Cary Audio Design, within 15 days of your purchase. Warranty restrictions and

applications may apply. Consult the warranty section of this manual. Export models

operated outside the USA are covered by local warranties assigned by your local Cary

Audio distributor.

SLP-308 PLACEMENT

The SLP-308 is designed for use inside of homes. It must be protected from the

elements and temperature extremes. For example, avoid placing the unit in extremely

hot locations such as near or on top of radiators or other home heating devices. Its

location among the user’s home audio components is not critical.

POWER REQUIREMENTS

The SLP-308 is designed to operate from AC house current mains. The design voltage is

120 Volts AC at 50/60 Hz. Export units have settings for 100/200/220/240 Volts AC at

50/60 Hz.

INTERCONNECT CABLES

The interconnect cables from the output jacks of the SLP-308 to the input jacks on the

power amplifier can be any convenient length your set up requires. The choice of a high

quality interconnect cable is important. Your Authorized Cary Audio Design Dealer will

have proper interconnect cables in stock for this purpose. The low output impedance of

the SLP-308 will run long interconnect wire runs, as long as 30-40 ft., without a

problem. We suggest wires with good shielding if you live near transmitter towers for

TV or radio stations.

OPERATION

Your new SLP-308 preamplifier is ready for operation after the various interconnect

cables have been installed and the unit is plugged into the household AC mains 120 Volt

AC wall socket. The SLP-308 is provided with functional, useful front panel controls

with an attractive and logical layout.

POWER SWITCH

The toggle power switch is located at the left side on the SLP-308 preamplifier front

panel. The switch operates in the following manner:

OFF (Down position) Removes all AC voltages from the SLP-308 power supply.

ON (Up position) Turns on the AC voltage to the power transformer primary

on. The power transformer has a 200% duty cycle. In simple terms,

the transformer is capable of operating two (2) SLP-308 preamplifiers

continuously 24 hours a day. We recommend that the AC power

switch be left in the ON position at all times. The SLP-308 sounds

much better after 100 hour burn in and when warmed up for _ hour.

Operate LED This blue LED will light after the SLP-308 is warmed up and

biased properly.

VOLUME CONTROL

The gain of both left and right channels is controlled simultaneously by this control. The

control potentiometer is of such high quality that the tracking error is less than 0.5 dB

from 0 to -60 dB. The program source remains in balance over the entire range of this

control. The taper rate of the volume control has been chosen to provide a rapid

increase in gain over the first half of rotation and slower gain increase above 12:00

position. The volume pot is controlling the input signal to the first grids of the 12AU7

tubes. The volume control has a DC motor attached for remote operation. The blue

LED in the volume knob is confirmation at a glance as to the overall level when you are

too far away to read the output level meters.

SELECTOR SWITCH

The 4-position rotary switch connects a choice of input program source, both channels

simultaneously. All program line sources are selected from this front panel 4 position

switch. As you switch from source to source inputs, you will hear a soft mechanical

clicking sound. This is normal and proper. The clicking sound is from the double pole,

double throw (DPDT) gold plated relays switching input positions.

WARNING!!!

MAKE NO ATTEMPT TO PUT THE SLP-308 INTO SERVICE WITH THE

TOP OFF OR THE CABINET OPEN. NEVER OPERATE THE SLP-308

WITH THE TOP COVER REMOVED. CONTACT WITH THE

OPERATING VOLTAGES PRESENT INSIDE THE SLP-308 CAN BE

FATAL!

FACTORY SERVICE

If it becomes necessary to replace any parts in the SLP-308, the same brand and part

number and style should be used. New parts are available from Cary Audio Design, Inc.

1020 Goodworth Drive, Apex, North Carolina, 27539.

Careful consideration has been given to the design of your new SLP-308 preamplifier to

keep maintenance problems to a minimum; however, it is possible that some problems

may arise. If this occurs, we suggest contacting our Customer Service Department at

phone number 919-355-0010 from 1 to 5 PM, East Coast time to describe your

problem in detail. Do not return the SLP-308 to the factory without a Return

Authorization Number (RMA number) from the Customer Service Department. As the

packing and shipping is being done by others, Cary Audio Design will assume no

responsibility if the transportation company refuses to pay a damage claim due to your

improperly packing or for lack of insurance should the unit be lost or damaged in

shipment from you to us.

SPECIAL NOTE:

Your new SLP-308 preamplifier is a polarity inverting design. This means that a positive

direction musical signal coming into the SLP-308 will be polarity inverted as it is

amplified and be sent to the power amplifier as a negative direction signal. The SLP-308

has one gain stage and one buffer stage in each channel. Absolute polarity inversion is

common on many high-end preamplifiers. If you are concerned about ‘Absolute Phase’

in your system, reverse the positive and negative leads either on the back of BOTH

loudspeakers or at BOTH the speaker output terminals of your power amplifier.

Remember to do this for both channels. However, please remember to switch the

phasing only at the amplifier or only at the loudspeaker, not at both places. Operating in

the polarity inverted phase mode will not harm anything.

Cary Audio Design

1020 Goodworth Drive

Apex, North Carolina 27539

Tel: 919-355-0010

Fax: 919-355-0013

[email protected]

www.caryaudio.com

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