I really liked the original, colored sound of these amps, but it was gone when I finished upgrading two of them. The sound is now much more open, detailed, and uncolored !
Upgraded all non-electrolytic caps to polyproprolene or polystyrene types, and bypassed the power supply electrolytics with Solen PP types. Tripled the input impedance to better match the tube line stage capabilities, and strapped the two input channels together internally for bi-amping (the blue cable running across the PCB). Replaced the input RCA and output speaker connectors. Upgraded the output wiring. Changed a few resistors to 1% metal file types.
The capacitor, wiring, and vibration control upgrades resulted in an amazing improvement in these fine speakers sound quality Detail, imaging, and tranparency are in a whole different class now.
Isolated interface circuit board, box, and panel assembly with sorbothane strips and rubber grommets. Built an MDF amp stand to fit on top of Interface and woofer box.
I started to fix a loose arm drive belt problem. But once the table was in the workshop, I went nuts ! Now quiet and smooth, it rivals some high end tables, without the hassle of dealing with their delicate arms. It's a joy to play records on.
With all the work and problems I encountered all the way, I now know this turntable system much too well ! If you need some help with yours, call or email.
If you want to work on your PX-2 turntable and don't have a service manual, I can sell yoy a package of copies of the Service Manual, Parts List, Owners Manual, and Literature sheet for $10. Just Contact me
This wonderful CD machine is a hidden jewel, but everything can be improved a little, right ?
Constrained layer sheets to damp case vibrations. Sorbothane and Mordite on transformers and bearing caps. Internal cleaning and dressing.
Mounted on BDR cones with .5m Goertz MicroPurl interconnects.
It's an audio system, so any little thing can get in the way of the best sound.
Cardas Caps on unused RCA plugs. Ferrite core Blockers for external preamp and subs power supply cables. Iron trivet heat sink for the Acoustat bias supply power wall warts.
Velco strips and plastic spring clamps for dressing cables (separate AC, line level, high level, and antenna bundles).
Various Vibrapods, cones, spikes and other vibration isolation devices.
Separate AC circuit direct from breaker box, hospital grade sockets, and (some) plugs. Separation of analog and digital/RF device power at the Monster HTS-2000 power strip, and in cable routing.
Replaced all interstage couplers with Wonder Caps, Replaced power supply caps with new photoflash electrolytic capacitors and bypassed with some PP's.
But this thing really needed all the capacitors upgraded (and probably a lot of resistors) as there is so much tone shaping circuitry, so I sold it off. So some one else will have to do that...
Added regulated +/-150v and +/-15v supplies. improved +5000v supply with doubled capacitance and bypass's. Upgraded all caps and resistors, experimenting with different types. Various quad op-amp devices. Converted to a star grounding scheme. Added an external power switch, and ceramic tube sockets, and more...
These amps are no longer in my possession, or I would post some pictures
Discrete phono and line amp circuits from an Audio magazine article, Audio Amateur 'Pooge' power regulator circuits (independent right and left +/- supplies), my own switching setup (some by onboard relays), and a beautiful homemade precision stepped attenuator. And a bit of an ARC case styling.