After overbuilding and several rebuilds of the actual Preamp section of my DIY DS Audio Phono Preamp (not to mention bending the DS003’s Aluminum Cantilever - shout out to TMR & Musical Surroundings for getting me a rebuilt cart. in exchange for my Cart…$$$).
I built version two for a friend (just charging him for the parts including Solid Silver wiring on the audio paths).
The PCB that was done for me looked great in concept and not so great once implemented. The inverse RIAA filter had phase shift issues while the dual mono single channel opamps worked perfectly. Problem was I’d put a shorting jumper between the active filter and the opamp gain stage so that the user could bypass the opamps and use a gain stage of their liking (tubes or Transformers - e.g Bob’s Device’s). Again, great concept but the PCB didn’t work when the jumper was shorted. Noise and attenuated signals which I’d chased down but couldn’t fix.
The board will be respun from my lessons learned.
So I built a copy of my original setup using a pair of Texas Instruments OPA 828 Op-Amp evaluation PCB’s which I populated using precision SMT Caps & Resistors. The RIAA filter is an all throughole affair using a pair of “Bumblebee” reproduction Caps by Jupiter. The resistors are all 1% Vishay/Dale Metal Film. Lots of copper under both the green PCB and my SMT protoboard.
I tried mounting everything inside one box which did fit, but I was getting noise induced by the Toroidal Transformer and the maybe by the various DC Voltage Regulators required for the DS Audio circuit as shown on their website (doubt it though since my box works fine with the opamps right next to their neccessary Volt. Reg.'s).
So I ordered another chassis from Amazon and Siamesed them together by sanding the surface where I would then bond the chassis together with JB Weld. To further reduce any noise. I had some old 2 conductor stranded MIC cable that was of no use to me. It was fine for running long DC paths since it’s a shielded cable.
The results were excellent !
Since my friend doesn’t need the very expensive matching DS Audio Phono Preamp cause of one I built. He was able to splurge on the DS Audio DS W3 Line Contact/Boron Cantilever model.
With cheaper WIMA Caps in the 1st stage of the inverse RIAA filter.
WIMA’s replaced with the repro Bumblebee Caps.
) turned me onto JB Weld when he repaired customer’s oil pan (drained and dried of course) 35 years ago ! . I mixed the “Creamer/Hardener” as recommended. Smeared it all over the side and even drilled/cleaned the DC and audio holes and the chassis never split apart.