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)