Dynaco PAT4 Solid State Preamplifier

  •  New redesigned circuit boards with all new components  - WIMA, Vishay, Kemet, Panasonic, Xicon, PRP
  • Premium redesigned phono preamp section - your vinyl will sound awesome
  • New modernized regulated power supply with a toroidal transformer - silent operation - "no pop" power on and off
  • Operates from a standard wall outlet - 120 Volts AC - no step down transformer needed
  • Dead quiet and no hum, static or buzz - great sonic detail and superb soundstage
  • New volume control, stepped design by ALPS, super accurate tracking - retains the loudness function too
  • New selector control with electronic relay controlled switching - no clicks or pops or thumps
  • Gold plated RCA jacks and a new phono grounding lug
  • Blue LED illuminated power switch to indicate power on / off - time delayed - silent power on / off
  • All rocker switches are serviced, cleaned, deoxit treated and function properly
  • Original 1/4" mic input and headphone output jacks were cleaned and function properly
  • Faceplate and knobs are original and in excellent condition - thoroughly cleaned
  • 4 new rubber feet w/ steel bushings - new black two prong power cord - original fuse holder
  • Overall cosmetics are really quite nice, just a few nicks as seen
  • Cover is dark metallic grey - looks outstanding - no dents or dings
  • chassis is rust free and has been hand cleaned and then polished
  • Rear panel AC accessory outlets are in excellent condition and all function properly - (2) switched, (2) unswitched
  • Output impedance is 500 Ohms

New advanced design circuit boards designed by Dan Joffe from Akitika / updatemydynaco. This circuit has an output clipping level typically greater than 8 volts into 100K load. Most amps only need 1 V RMS to drive to full output. Distortion at 1 V RMS out is only 2nd harmonic, and it is better than 96 dB below the output level.

A quieter, more accurate phono preamp (moving magnet cartridge) with much higher overload capability. Built-in ultra-low frequency filter. Built in de-click resistors. 1% metal film resistors for better linearity, lower noise, and more accurate channel-to-channel matching.

Power-up/power-down transient suppression relays and time delays to avoid nasty noises with power up/down.

Front Panel was totally recapped and received new resistors too, all pots serviced with Deoxit and electrical cleaner.

The phono preamp has ground-planes and bypass capacitors that give it great high-frequency stability and noise rejection, a built-in second order high-pass filter that minimizes the woofer wobble caused by record warp and a second-order low pass filter that makes it much less likely to pick up external signals like switching transients and radio stations. The phono preamp picks up much less of the hum fields inside the PAT-4, very quiet and free of hum.

The only possible hum you may pick up comes from the phono cables outside of the PAT-4.

The replacement volume control is an Alps/Alpine 250K 23 position detent pot with a loudness tap. This is just like the original pot, but with the addition of the detent feature.

New electronically controlled selector switch that has crosstalk that's at least 33 to 100 times less than the original switch. Clicks and pops are eliminated with this selector switch.

The outputs are now electronically regulated too. That means the output voltage isn’t affected by normal changes in input line voltage (e.g. changes in line voltages when appliances turn on and off). The outputs don’t change with changing signal load produced by changes in the musical signal. That keeps the amplifier stage’s operating point more consistent, and reduces distortion. The outputs have less noise and hum that often appears at the preamp outputs.

Replaced the original transformer with a specially designed toroidal transformer that practically buries hum in the phono noise floor.

A new regulated power supply mounts in place of the old capacitor can and is far superior to the original. The impulsive noise and current path through the diodes and main filter caps has a much smaller loop area than the original power supply arrangement. This diminishes hum fields from the power supply. It is electronically regulated with super quiet 38 Volt and 17.5 Volt rails.

The New Tone Control Switch replaced the old Hi Filter switch with a new two position rotary switch. In the OFF position, the tone controls are disabled, "out of circuit". In the 15 position the tone controls maintain their normal function. The other two positions of the HI FILTER switch (10 and 7) are intentionally not functional now.

The Faceplate and Knobs are original as is the chassis and cover

The power cord and feet are brand new

This item is not covered by a warranty:

Some of the components still in this unit are original, most are new. This unit is considered as "rebuilt or reconditioned" only. This unit is classed as a modified vintage unit. We thoroughly test these types of units before offering them for sale. However due to the presence of these original parts some of which may no longer be available if a replacement is necessary we cannot offer a warranty or guarantee of any kind on units of this class.