Dynaco PAS3X Tube Preamplifier - Fully Rebuilt
The exceptional unit offered here was originally a 1974 PAS built from a kit and did not have the 3X controls. However, some time ago, I was fortunate to have acquired an unused, new in the box, intact NOS Dynaco TC-3X kit. This preamp was in such good condition, although needing an electronic overhaul, I just had to use these 3X parts for this ultimate 3X PAS rebuild. Time had taken its toll on the original TC-3X kit included resistors and capacitors so those were discarded and fresh high quality film caps and new resistors were used. The tone controls themselves were also cleaned thoroughly with contact cleaner then treated with Deoxit before being installed.
I wanted to lean towards originality with this rebuild, but also wanted to overcome a few weak points in the original design. Aside from adding the 3X tone controls, I removed all of the AC accessory outlets from the rear panel to reduce EMI by eliminating that wiring. I added an adjustable brightness Dynakit LED to reduce the load and draw on the power transformer.
I installed a modern filament supply which also neatly adds a fuse to the AC mains. This module eliminates the old & often problematic twist lock can type multi section quad capacitor, providing better regulation, cleaner quieter power and longer life, a really great upgrade. This module also slightly increases capacitance. The quad cap can seen in the chassis is simply there to fill the hole, it is non functional.
The input and output RCA jacks and the jack panel are new from Dynakit. The RCA jacks are gold plated for corrosion resistance and improved contact. The panel itself is made from FRP and is very sturdy to minimize flex and provides improved grounding. The new jacks retain all the function from the original design but provide more clearance for modern interconnects by having a staggered arrangement. A nice brass phono grounding post has also been added to the back.
All of the original slide switches were discarded in favor of brand new parts, all new Mallory & IC capacitors, new resistors and new wiring were also installed across the entire front panel assembly.
Brand new circuit boards. They follow the original circuit faithfully as well as retain the precise component locations. These boards have plated through holes, a much better design than the single sided eyelets found on both types of the original boards, They also have slightly wider and heavier solder traces, they're simply a better quality circuit board. They have ceramic sockets with gold contacts and are loaded with high quality components that make this preamp perform better than it should. The paragraph below will outline the components.
Modern components were used in this build, although generally smaller in physical size they have higher voltage ratings and improved performance characteristics over their old counterparts, this additionally relates to improved sonic performance and reliability. Metal film and carbon film resistors by PRP, TE, Vishay, Panasonic (Matsushita) and Xicon ensure the circuit is operating within the desired range and doing its job very quietly. The capacitors are from CDE, Illinois Capacitor, ICEL (Nichicon) JB, and Panasonic. The original Dynaco PAS circuit, when populated with these high grade components sounds like heaven. This preamp will blow you away, it sounds incredible.
This "supermodel" class Dynaco includes a brand new perfectly balanced and test matched set of four Electro-Harmonix 12AX7 Gold Pin Tubes and a beautiful NOS genuine Dynaco 12X4 rectifier tube with its original box. The 12AX7 tubes were ordered specifically for this build and include their original boxes. The unit has been burned in for over 24 hours using these tubes to ensure you have a wonderful "right out of the box" listening experience. If you're into vinyl, this Dynaco will bring you great joy, the phono preamp stage is amazing.
The selector switch is original and works perfect, it had obviously seen very little use. It was thoroughly but very carefully stripped of all the old wiring, components and solder, then carefully cleaned and serviced with Deoxit before being reinstalled. All new high voltage stranded wiring was used to reconnect it and also to rewire the entire preamp.
The volume and balance controls are original and track very nicely. They were removed, serviced and checked before being reused. The blend switch was serviced, outfitted with new resistors per the 3X tone control modification guidelines.
The original Dynaco power PA-211 transformer is in immaculate condition, voltages checked dead on spec.
The amazing faceplate and knobs are original to the unit as well as the chassis, cover and bottom plate. New feet and a new power cord were installed on the unit.
Shipped insured for full value - signature required*
Tubes will be removed and safely packaged within the box along with parts lists, wiring diagrams, and a tube installation chart.