Poogeing the SACD: The Pioneer 563A

[blank527]

Tranny above the DSD-chip.

[blank527]

Schottky diodes.. upgraded power supply.
Etc.

Thank you,

Remco Blankesteijn.

[Nic.M]

Hi all,

Just to keep everyone who is interested up to date, I finally finished my planned changes to the player last night.
Here is a review of what I have done.

-Upgraded electrolytic caps on the audio, and psu boards as described in my former messages to this thread.

-Removed the output the stereo op amp and replaced it with an opa 2640, removed the ouput 47uf capacitors and 22k resistors to ground, and replaced with 4.7uf Rifa polyprop and 220k resistors.

-Piggy backed more Panasonic caps on the digital board, each one straddling the stock one, leads dressed with sleeving. This was tricky but it made a lot of difference to the smoothness of the musical presentation

-made and inserted a new linear psu +5v, +3v double regulated from 2 8v regulators from a dual primary-dual secondary xfrmr, 2 diode bridges, etc. Removed the stock +5v regulator, cut 3 volt trace near cn601 to insert new psu.

- used another transformer to make +/- 15 volt regulated with 3 terminal regulators. Reregulated these with Sulzer regulators to +/- 12 volts. These were used for a completely new output stage
description to follow.

Nic.

[Nic.M]

The new output board holds in addition to the 12 v regulators, another opa2604 op amp on a socket (for future experiments?)

This output stage has a balanced input as described in the DSD1791 spec sheets(p30) and their specified filter. I simulated this in SWcad and it worked out very well with a cutoff of about 76kHz and about 6 volt pp output.

To get rid of any residual offset I used two 2n5457 in a "totem pole configuration +12V on the drain, source to a 5k pot in parallel with a 1.3k resistor, the low end of the resistor into the drain of the other fet whose gate is tied to -12v and whose source is tied to the same point through a 1k resistor. The output of the filter stage goes into the gate of the top fet through a 1K resistor. If this is confusing to you, check The Audio Amateur 2/90 pg 14, an article by Paul Marchese.

The output of this stage, from drain of lower fet goes into an LT1010 discrete buffer, coupled to the output with a 75 Ohm resistor and no caps!!!! Nulling the offset is a snap with the 5k multiturn trimmer. I also put in an output relay to ground the signal, taking the sense pulse from Q203. The relay control uses 12 v from the machine. New output jacks were fitted. I took the output from the stock dac chip from R231/234-R238/243.

That's it. Or almost. I changed AC socket to the power cord and now can experiment. Pictures will follow

Nic.

[Nic.M]

This is the picture of crammed machine from the top.

[Nic.M]

This is a different view

[Nic.M]

The Back with new power cord and new output RCAs

[net-david]

Nic,

Looks great! How is the sound improvement?

I need to get busy on my mods, but I've been putting in too many hours at work. Hopefully, it will calm down soon.


David

[Nic.M]

Hello David,

I had a chance to listen to Cds ,Sacds and one DVda last night and earlier this afternoon. In short, the overall presentation is smoother, with a considerable quieter noise background, and a gorgeous midrange.

The bass is more solid and the bass line in dense recordings is easy to follow. There is more differentiation between similar instruments such as clarinet and soprano sax playing the same lines.

Female voices in some cuts which were overly sibilant due to overclose miking are tamed somewhat, (hey, you can't fix lousy recording techniques), but well recorded voices on SACD such as Patricia Barber's in Nightclub are to die for.

Piano, which I have always thought that SACD did particularly well on really seems to shine with the mods. Chick Corea's work with Rubens Rubacalba in Rendevous in New York is just fabulous.

Depth of image, space around soloists and orchestral sections all come through better.

In a word, everything has improved. My favourite CDs also sound very good. Charlie Haden’s Nocturne cd is really warm and intimate sounding, just as on my veeery elaborate self built transport and outboard dac. ( Similar output section Op am-Fet-Lt110 buffer stages) The Buena Vista Social Club DVD audio sounds convincingly spacious, lively and airy.

By the way, all this was done comparing the modded unit to a stock one which belongs to one of my friends, using the same preamp, cables, etc. We just muted the preamp and interchanged the interconnect.

A very positive review, indeed.

Nic.

[net-david]

Nic,

Would you be willing to share the output circuit you used? I am especially interested in the section to reduce the offset.

So now my projects are:
1. Build the Gain Clone kit from BrianGT of the chip amp forum.
2. Assemble my Jordan JX92 speakers.
3. Mod my 563

I need more spare time....

David