Dynaco PAT-4 pre-amplifier

 

The PAT-4 is a solid state countrpart of the renowed PAS-3X Dynaco stereo preamplifier, providing the same superior performance with a number of added features. The PAT-4 can be used with any tube or transistorized Dynaco power amplifier or virtually any other power amplifier, tube or transistor. Available either as an easy-to-build kit for the hobbyist, or fully assembled and tested, the PAT-4 harmonizes with the Dynaco FM-3 stereo tuner and is directly interchangeable with the PAS-3X in cabinet installations.

The PAT-4 exemplifies Dynaco's long-standing reputation for excellence achieved through innovation and a constant striving for simplicity in both engineering and operation. A remarkably low level of noise and distortion has been achieved - below the level which can be measured with commercial grade test equipment - through the use of carefully selected silicon transistors in a circuit utilizing both DC and AC feedback. Frequency response is extremely wide to prevent deformation of square waves and other signals which depend on wide-band, low phase shift response for accurate reproduction. Overall performance superior to all other transistorized preamplifiers is assured.

An important specification frequently overlooked in evaluating preamplifiers is phono overload capability. The PAT-4, with its 80 mV phono overload point, cannot be overloaded by any magnetic cartridge made today. Transistorized preamplifiers in particular frequently have had poor phono overload characteristics and in the absence of any such overload specification, you have no assurance that the phono stage will not distort severely on many loud passages.

 

The PAT-4 kit is supplied with two identical preassembled etched circuit boards which include virtually all the components except the power supply and the controls, greatly simplifying and speeding construction of the kit, and assuring operation and absolute reproducibility on completion. Each circuit board has been in circuit tested prior to shipment. An open, uncluttered chassis layout provides ready acces for assembly and trouble shooting.

Like all Dynaco products, the PAT-4 is the culmination of years of painstaking design. It has been acclaimed by renowed audio experts, like Julian Hirsch, who wrote in Stereo Review ; "in sonic quality, we would unhesitatingly say that the Dynaco PAT-4 is unsurpassed by any preamplifier we have seen, … a remarkable unit and unmatched at anywhere near its low price …"

 

Specifications

Frequency Response: 

High level Inputs :  10 Hz - 100 kHz ±0,5 dB

Low level Inputs :  20 Hz - 20 kHz ±1 dB

Distortion (at rated 2 volt output):  less than 0,05% (20 Hz - 20 kHz)

IM Distortion:  less than 0,05% with any combinaation of test frequencies

Hum and Noise:

Magnetic phono :  70 dB belowa 10 mV input signal

High level :  85 dB below a 0,5 volt input signal

Gain

Magnetic Phono :  54 dB at 1000 Hz (3mv for 1,5 V out)

High Level :  20 dB (.15 V for 1,5 V out)

Tone Control Range

Bass :  ±16 dB at 50 Hz

Treble ;  ±12 dB at 10 kHz

Maximum Output:  10 Volts into high impedance; 5 Volts into 600 ohms

Impedances:

Magnetic Phono :  47 k Ω

To tape :  from Low level inputs  600 Ω

Tape Head :  100 k Ω

High Level :  100 k Ω

To Tape : from High level inputs same as source

Audio Output :  600 Ω

Amplifier Input :  Nominal load 10 k Ω or higher

Inputs:

Low level or High level RIAA magnetic phono or ceramic phono;

NAB 7-1/2" tape head;

Special (normally microphone)

Tape amplifier

Tuner

Spare High level for TV, etc

Front panel High level

Outputs;

Tape output Ahead of controls

2 Audio outputs (one switched by front panel jack)

Front panell output

Front panel Controls

Selector switch; Volume control; balance control; 2 bass controls; 2 Treble controls;  High Filter switch at 15 kHz, 10 kHz and 7 kHz; Loudness Compensation switch; tape Monitor switch; Low Filter switch; paired (A + B) with 6 dB blend for 3rd channel output, or stereo; illuminated power switch.

Semiconductor Complement:  8 Transistors; 2 Diodes

Power Consumption:  5 watts 120/240 V 50/60 Hz AC

Dimensions (W x H x D):  13-1/2" x 9" x 4-1/4"

Weight (shipping):  4,5 kg (10 lbs)