DYNACO PAS-4 Owner's Manual
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DYNACO PAS-4 Owner's Manual

Vacuum tube preamplifier
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Vacuum Tube Preamplifier
Owner's Manual
R
PAS-4
CD
SOURCE
VIDEO
TUNER
2 to 1
AUX
PHONO
INPUT
PAS-4
SOURCE
1 to 2
TAPE 1
TAPE 2
TAPE DUBBING
TAPE MONITOR
PAS-4 Vacuum Tube Preamplifier
LEFT
RIGHT
EPL
MONO
IN
IN
BALANCE
VACUUM TUBE PREAMPLIFIER
VOLUME
POWER

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Summary of Contents for DYNACO PAS-4

  • Page 1 PAS-4 Vacuum Tube Preamplifier Owner's Manual VACUUM TUBE PREAMPLIFIER PAS-4 SOURCE SOURCE VIDEO TUNER 2 to 1 1 to 2 TAPE 1 TAPE 2 LEFT RIGHT MONO PHONO INPUT TAPE DUBBING BALANCE VOLUME TAPE MONITOR POWER PAS-4 Vacuum Tube Preamplifier...

  • Page 2: Table Of Contents

    Tube Replacement ................7 Alternate Tube Types ..............8 Minimizing Noise in the System ............9 Warranty ..................10 PAS-4 Specifications ............... 11 Schematics ..................12 PC Board Parts List ................. 14 Please read this manual thoroughly before operating your new PAS-4.

  • Page 3: Introduction

    - both solid state and vacuum tube designs - regardless of price. Its flexibility and full-featured styling is without parallel in affordable preamps. Your PAS-4 was designed and built entirely in the USA. We are proud to offer this outstanding preamplifier to discerning audiophiles the world over.

  • Page 4: Rear Panel Inputs And Outputs

    Preamplifier Main Outputs Two pairs of outputs are provided for your power amplifier(s). The two left channel RCA jacks are connected directly together inside of the PAS-4, as is the right channel pair. EQ (External Processing Loop) "EQ Out" are line level outputs which can be connected to the inputs of an external signal processor such as an equalizer, time delay, or noise reduction unit.

  • Page 5: Operation

    Turn-On Delay and Visual Indicator When you turn on the PAS-4, the lamp above the PWR (power) switch glows GREEN and a timer circuit is evoked which keeps the preamp outputs at zero volts during the warm-up period. This 45-second warm-up period allows the tube filaments to fully heat, the high-voltage section of the power supply to reach full potential, and for the preamp output circuitry to settle, (avoiding loud turn-on "thumps").
  • Page 6 With the PAS-4 there is a solution to the use of lower input impedance tape decks. Simply keep the TAPE DUBBING switch positioned to ‘1 to 2’ or ‘2 to 1’ when the deck is not in use. This disconnects the signal...

  • Page 7: Tube Replacement

    99% of the time it will be due to a faulty tube The most likely source of tube noise in the PAS-4 is the phono section first stage tubes V1 (left channel) or V4 (right channel). Less likely, but to be suspected next, would be the phono stage second stage tubes V2 (left) or V5 (right).

  • Page 8: Alternate Tube Types

    Some audiophiles feel strongly about which manufacturer and/or particular version of vacuum tube to use for specific applications. The tubes installed on your new PAS-4 have been selected to provide the best sound and long life.

  • Page 9: Minimizing Noise In The System

    Minimizing Noise in the System Hum is caused by amplification of the 50 or 60 Hz AC power line signal that is transmitted via the magnetic fields around power transformers and power cables. RF interference usually comes from inadequate shielding of cables or components. If any of these types of noises are encountered, one or more of the following pointers concerning proper component positioning and grounding may be of use: Ensure that each system component, especially the preamplifier, is located far enough away from the other components so that they will not pick up hum from them, and that the AC power cables are not...

  • Page 10: Warranty

    Warranty For three years from the date of purchase (one1 year for tubes) Dynaco will repair, for the original owner, any defect in materials or workmanship that occurs in normal use, without charge for parts or labor. It is the owner's responsibility to provide transportation to the authorized Dynaco service representative who will perform warranty service, and to present proof of purchase in the form of a dated sales slip when requesting service.

  • Page 11: Pas-4 Specifications

    PAS-4 Specifications Phono Section GAIN: 40 dB RIAA ACCURACY: +/- .5 dB from 20 Hz to 20 kHz PHONO OVERLOAD: 500mV RMS @ 1kHz MAXIMUM OUTPUT CAPABILITY: 60V RMS @ 1kHz 50V RMS @ 20kHz (for 1% THD) THD: less than .025% @ 2V RMS Output...

  • Page 14: Pc Board Parts List

    PAS-4 PC Board Parts List DESCRIPTION DESIGNATORS Resistors 100 ohm, 1/2W, metal film R201 140 ohm, 1/2W, metal film R28, 128 221 ohm, 1/2W, metal film R21, 25, 121, 125 249 ohm, 1/2W, metal film R12, 112 301 ohm, 1/2W, metal film...
  • Page 15 PAS-4 PC Board Parts List (cont.) DESCRIPTION DESIGNATORS Capacitors (cont.) 10.uF, 25V, alum electrolytic C222 22uF, 25V, alum electrolytic C220, 223 22uF, 250V, alum electrolytic C212 33uF, 450V, alum electrolytic C205, 206 470uF, 25V, alum electrolytic C221, 224 1000uF, 6.3V, alum electrolytic...

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