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SCD-1/777ES Output/Grounding Mod

208.234.125.89

Posted by jhietbrink on October 25, 2001 at 15:58:32

You may have wondered about upgrading the output components of your SCD-1/777ES for several reasons:

- The RCA jacks are not the best quality, at least on the SCD-777ES. To be more specific, they’re plastic and unplated brass. The jacks on the SCD-1 may be better – at least the part numbers for the jacks are different.

- The grounding is – curious. There is a very heavy copper bar that connects the audio signal and analog power supply grounds to the RCA jacks and back panel creating a large buss ground. Sony is even proud of this arrangement stating that “to optimize grounding, the audio output terminals are connected to the audio circuit board using a thick copper plate”.

Sony’s attempt to “optimize grounding” results in the RCA outputs sharing a common ground path to what should be the star ground -- undoubtedly resulting in interchannel crosstalk. In addition, the connection between the power supply ground and the chassis ground runs through the audio grounds at the RCA jacks, creating a propensity toward humming in some systems. The Sony engineers are definitely of the “a ground is ground is a ground” school of design. That said, I’ve found grounding problems in many high-end audio components.

- And the chassis wire is less than ideal. If you look v e e e ry carefully, you can see that it’s sourced from Hitachi and that the conductors are six 9s OFC copper. A postmortem exam revealed the insulation is definitely not Teflon and is probably PVC or something equally nasty. The conductors are stranded and the ground is wrapped loosely around the positive conductor to make coax of sorts with poor shield coverage. As if this were not enough, the wire is molded to create conductor pairs so the right and left channels are as close together as possible. Oh -- and the power cable for the muting relay is tie wrapped neatly to the signal conductors (and on the SCD-1 the cables to the balanced outputs are included in the tie wrapped bundle).

Now, changing RCA jacks and audio signal wire usually isn’t that big a deal – but it is on the SCD-1/777ES. Fortunately, the back panel is removable and removing it is the first step. Then the PIN board (that’s what Sony calls it – I would call it the Output Board) has to be unsoldered from the RCA jacks (rather easy with solder wick) and then the RCA jacks can be removed.

I replaced the stock RCAs with Vampire OFC RCA jacks with Teflon insulation, my personal favorite. Because the holes in the back panel were already too large for either size of the Vampire connectors, I decided to reuse the copper buss as a mounting plate – after trimming off the bar that attaches to the audio board grounds with a Dremel tool. The holes in the buss are slightly larger than 3/8 inch, but they still worked with the 3/8 inch RCA jacks. Then I had to enlarge the holes in the back panel with a Unibit to 5/8 inch so that they would clear the insulating washers on the new RCA jacks. And since the back panel is made of steel – I had to paint the edges of the enlarged holes.

And there’s more – the PIN Board also needs to be modified. I decided to slide the PIN Board over the new RCA jacks and secure it in place with a second set of nuts on the RCA jacks. I also decided to run the signal wire directly to the RCA jacks – so I cut out the board and traces that make the center pin connections, leaving nice holes a little larger than 3/8”. I had to use thinner inside insulating washers than were supplied with the RCA jacks to have enough space for the second set of nuts. Fortunately, I had thinner washers and extra nuts on hand that were left over from other RCA jack upgrade projects.

For the new audio signal wire I used Kimber AGSS silver wire – again a personal favorite. For now, I soldered the new audio signal cables to the plugs that attach to the Audio Board. The Audio Board will come out on a future mod and I will then solder the cable directly to the board. To make the PIN Board mute relay operational, I shortened the old audio signal wires and soldered one to each RCA jack. (The mute relay just shorts the outputs to ground.)

To reestablish the output grounds, I used short lengths of AGSS terminated with a ring connector and screwed to the Audio Board ground connection. So now there are separate output grounds for each channel that come together in a star ground of sorts. To reestablish the earth ground, I used a short length of 14-gauge wire with crimped ring connectors at each end. One end is attached to the Audio Board ground screw and the other end is attached to the chassis ground screw.

So was this all worth it? Yes, absolutely. The mod will break in more yet – but here’s what I’ve observed so far. I was immediately struck with how open and clear the sound has become. Lyrics are much more easily understood – even though I thought they were perfectly intelligible before. There is more body to the music– especially with CDs. Highs are more extended – and sweeter. Dynamics are improved, especially microdynamics. And there is no ground loop induced hum.

This mod together with the AC Board mod I completed earlier has vastly improved the SCD-777ES. The next mod will replace the AD712 op amps on the audio board – op amps that no one thinks sound especially good.

This post is made possible by the generous support of people like you and our sponsors:

VH Audio

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