It was an awful lot of work... The top is made of opaque, black glass, giving some extra space for ventilation, which is covered with perforated
sheet metal. I remember I experimented with a mixture of linseed oil and black paint to get an even surface on the sheet metal.
I even painted the sheet metal upside down so it could not catch dust.
But again the top is glass, not acrylic - Took some time to find a glazier who was
able to grind rounded edges. The back panel had to be carefully modified with heatsinks as well.
The reason:
I wanted the player that the boutique manufacturers promise but never built or for offer for obscene prices.
The built quality back in the eighties was great, so I had this already.
But of course the PCM56-based DAC section is outdated. (A friend still prefers his unmodified
OMS-5EII over a much "better" and younger Marantz CD-10)
Anyway: I ripped out the original DAC section of my Nak and replaced it with Twistedpear´s Buffalo II / ES9018 DAC
+ shunt regulated power supplies + single ended and balanced output stages.
The complete section is galvanically isolated from the Nakamichi´s ground and chassis, a unit within another unit.
This is why the DAC sits in it´s own enclosure inside the Nak. Of course transformers are used to isolate SPDIF.
Some cables are that thick because they are shielded with a second shielding that is only connected to the Nakamichi chassis.
Every cable carrying voltage was wrapped with silicone tubing as well.
Toroids had to be added as well, as many new secondary voltages were needed.
As the DAC only accepts SPDIF and I2s, I had to add a transmitter to convert the internal
signal of the Nakamichi to SPDIF. This Nak is Sony-based, the first Nakamichis were Philips-based.
Some chips from TI do the work of transmitting, DIT4096 or DIT4192.
But for them, a new clock had to be added as well, that feeds the transmitter with 16.9344MhZ and the Nakamichi with 8.4672MhZ
And because SPDIF + a complete DAC were there, an input selector was reasonable as well.
Though all inputs on the back look like RCA, one is optical.
DAC and Nakamichi can be switched on idependently.
The Power button on the front now functions as a selector for the inputs, the Nak itself + five SPDIF inputs...
BTW, the Sony CDP-101 and Toshiba XR-Z70 pictured above still wait for an SPDIF output.
Easy with the Toshiba as it seems to have the same internal data structure as Sony does, the Data, L-R Clock and Bitclock.
The Toshiba also has a clock oscillator (XTAL) that is a dividable of 16.9344, crucial for adding the DTI4096 providing SPDIF out
But interestingly, the CDP-101 misses an oscillator directly providing a dividable of 16.9344 through an Xtal, it must be generated by PLL...
Did not find the point to tap 4.2336 from yet...