Dynaco PAT-5

 Dynaco PAT-5 Bi-FET Preamplifier

The Dynaco PAT-5 is the control center and preamplifier for your high fidelity stereo system, which is used in conjunction with a power  amplifier, such as the Dynaco Stereo 120 or other basic power amplifier, and pairs of speakers.

When the outputs from the amplifier are connected to the preamplifier, two pairs of speaker may be selected, and any impedance  headphones may be connected to the front panel of the preamplifier.

The PAT-5 provides flexibility and features not found in many other preamplifiers.

 Coming from Dyna, that's really news. Never before in many years has Dynaco claimed marked sonic improvements when it has introduced a new model. Every Dynaco product has been designed for the perfectionist. The simple fact that the PAT-5 preamplifier is clearly superior to previous Dynaco tube and transistor designs is history making. Until now, they were classed with the most expensive competitors.

It includes complete facilities for two tape recorders, truly useful tone controls, external processor loop, monster-amp power and speaker switching capability, extra phono gain option, low impedance headphone output, 3-stage regulated supply, and it is quiet.

Best of all, it's a DynaKIT. Easy assembly, superior parts quality, assured results from complete in-circuit testing of every fully-assembled audio circuit board.

 Circuit Description

The components in the PAT-5 are of the highest quality to protect against failure, and all parts are operated conservatively with close tolerances to assure proper operation for many years. The transistors and integrated circuits have been thoroughly researched and selected for minimum noise and distortion in sustained use, and the printed circuit boards associated with audio signals have been pretested in the circuit to ensure that every unit will meet the laboratory prototype-like specifications.

Each audio channel of the PAT-5 basically consist of three circuit elements; preamplifier-equalizer circuit, control circuit, and tone control-output circuit. The power supply is fully regulated.

The preamplifieer-equalized is a direct coupled NPN/NPN transistor pair operated at 42 volts B+. Parameters have been adjusted for optimum noise, gain, frequency response, input acceptance, stability, and distortion. All feedback is DC connected. The input stage is not affected by the source impedance of the phonograph cartridge so that the cartridge cannot alter the RIAA equalization.

The control section of the circuit, which comprises volume, balance, stereo-mono, low and high filter functions, is driven by a voltage follower containing a PNP/NPN direct coupled transistor pair at low impedance.

The tone control-output section uses a high performance operational amplifier integrated circuit as the entire gain element. DC feedback around the operational amplifier is constant in all modes; only AC feedback is altered for tone control operation. The high frequency RC filter network utilizes an active, low noise two transistor NPN/NPN configuration.

The multiple-stage power supply uses a series regulator transistor with a separate zener diode generated reference voltage for the +42 volts used for the preamplifier circuit. The ±15 volt supplies utilize shunt design zeener diode regulation for the control and tone control-output circuits, and =15 volts for the active RC filter network.  A fully regulated supply has been chosen so that variations of line voltage from 100 to 130 volts AC (alternately 200 to 260 volts) will have no effect on audio performance. This is particularly important if a very powerful amplifier is used, where its current demands can exceed the wall outlet capability. The audio circuits of the PAT-5 therefore always remain stable, because the outputs from the power supply do not "pump" or shift in voltage.

Specifications

Frequency Response:

High Level Inputs :  ±1 dB, 10 Hz to 50 kHz

Low level Inputs :  0,5 dB of RIAA curve

Distortion at 2 Volts Output into 10 k Ω in parallel with 100 pf: 

THD :  0,007% or less (20 Hz to 20 kHz)

IM :  0,007% or less, with any combination of frequencies

Hum and Noise:

Magnetic Phono :  70 dB below at 10 mV input, at 1000 kHz

High Level :  90 dB below a 0,5 volt input

Gain:

Magnetic Phono (LO) to Audio Out :  75 dB at 1 kHz

Magnetic Phono (HI) to Audio Out :  63 dB at 1 kHz

Magnetic Phono (LO) to Tape Out/E.P.L. Out :  37 dB at 1 kHz

Magnatic Phono (HI) to Tape Out.E.P.L. Out :  43 dB at 1 kHz

High Level to Audio Out :  20 dB

High level to Tape Out/E.P.L. out :  Unity

Phono Input Acceptance

LO :  Greater than ±10 millivolts at 1 kHz

HI :  45 millivolts at 1 kHz

Tone Controls:

Bass :  Greater than ±10 dB at 50 Hz

Treble :  Greater than ±10 dB at 15 kHz

Filters:

Low :  -4 dB at 10 Hz, 6 dB per octave (conforms to RIAA phono playback curve)

High :  -10 dB at 10 kHz, 15 dB per octave

Voltage Output:

7 volts minimum into 10 k Ω or greater

4,5 volts minimum into 1000 Ω

Impedances: 

Magnetic Phono :  47,000 Ω in parallel with 220 pF

High Level :  50,000 ohms

Tape Output [from phono inputs/high level inputs]:  15,000 Ω / same as source

Audio Output :  less than 600 ohms

Separation at 2 volts, output into 10 k Ω; undriven input tarminated in 5K:

20 Hz :  70 dB minimum

2 kHz :  70 dB minimum

20 kHz :  45 dB minimum

Semiconductor Complements:

13 transistors; 2 ICs; 3 zener diodes; 4 diodes

Power Consumption:  12 watts, 120 V or 240 V, 50/60 Hz  AC

 Dimensions (W x H x D):  13 ½" x 4 ¼" x 11 ¾"

Weight:  5,9 kg (13 lbs)