ARC D-52d -  ('d' for Dave, of course !) from ARC D-52b:

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.

D-52d top view (open)
What a massive power supply ! Only 50 watts continuous, but a huge instantaneous reserve.
D-52d showing main circuit board
Notice how tightly this amp is packed ! There are two layers of circuit boards and replacing output transistors is a miserable job.
D-52d view behind front panel
Replaced the power cord with a heavy gauge 6' 3-wire shielded cord and added an internal ferrite core, along with a toggle type power switch (on top left) for convenience.

 

Acoustat Spectra 1100:

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.

Interface mods
Replaced electrolytic interface caps with Solen PP types. Added new input connectors and wiring. Cleaned up the boards and dressed wiring.
Woofer Xover mods
Replaced woofer crossover inductors with Alpha Core devices and bypassed aluminum spacers in the signal path with heavy gauge copper wiring. Disconnected poor internal connection to electrostatic interface.

 

Yamaha PX-2 Turntable:

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

Yamaha PX-2 Turntable
Added a motor cutout switch, access to all arm servo adjustment pots, and a VTA adjustment handle. Cleaned and lubed all arm drive bearing points, finially replaced the arm drive belts, dressed the internal wiring, and more.
Yamaha turntable with new phono connectors
Rewired arm to new output RCA connectors and ground, simplifying the signal path and allowing for cable experimentation.

PX2 turntable Detail PX2 tonearm Detail

Yamaha tuntable underside
Applied underbody coating to underside of platter, frame, and bottom plate, along with some constrained layer dampening under the arm assembly and some chunks of foam and lead here and there. Moved one power transformer to better balance the entire assembly.
PX-2 testing
Testing arm tracking with home made extension cables to troubleshoot a problem that turned out to be stretched drive belts.
PX-2 belt tension fix
To fix the most common problem with the PX-2, stretched drive belts, I finally came up with this solution. A couple of Acrylic blocks, drilled and tapped for screws through the grommet holes on the end of the belts, with a perpendicular tapped hole in one, and a clear hole in the other, for the adjusting screw and spring. This allows me to easily adjust the tension of the belt whenever necessary, without fooling with fixed spring length or other difficult to manage hardware. You'll need to do a little machine work on this, or find someone who can, but this should end belt tension problems with the turntable !

 

Theta CD Player:

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.

 

System Tweaks:

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.

 

Past Projects...

 

Harmon Kardon Citation 1 preamp:

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...

 

Acoustat Direct Drive amps:

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

 

Homemade Preamp:

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.

 

My PreAmp_1.jpg (20477 bytes)
Preamp and Power Supply. I Styled it somewhat like ARC gear. Note that RCA jacks are in an easy to access position, on top of the unit !!
My PreAmp_2.jpg (64833 bytes)
Plug-in perf boards for the Line Amp, Phone amp (underneath, left), and pre-pre amp board. Regulators and caps mounted to an aluminum plate (lower right).
My PreAmp_3.jpg (44145 bytes)
Separate raw power supply box. AC switching, 28 volt relay supply power LED.