Tube Marantz CD63

Hi Guys,

Here's some sharing on a recent project which is to add a tube gainstage (not a buffer) in a Marantz CD63.

As the CD63 is using a voltage output DAC, a low gain high current tube was used. In my case I opted for an ECC82/ 12AU7 which was much more suited than what I usually use i.e. 6922.

The project was basically to cut off and tap the analog signal at the DAC output and feed it directly into the ECC82's grid via a 4.7Kohm grid stopper and grid leak resistor of 100Kohm was used.

A dedicated 120VAC transformer was used to derive the HT voltage of around 140VDC. CRC filtering in the PSU is 220uF 2.2Kohm 220uF then feeding Anode resistor of 11Kohm. Cathode resistor is 560 ohm.

Another dedicated 12VAC transformer was used to power the filament. I used a 2 ohm resistor in series with the filament to reduce start up transient of the heater and then used 1k ohm resistor on each leg of the filament and tied it to ground hence forming virtual center tap to reduce noise.

From my experience the CD63 & 67 series uses a pathetically small EI transformer to power the whole CDP hence it's really underpowered. So to reduce energy usage as much as possible, all analog stage items that saps up energy was removed i.e. the dual opamps, capacitors for the opamps and capacitors for the HDAM module.

Stock player before mod:


Overall after mods:

Going into the details....


The rear panel was removed, holes were drilled and then the 2 transformer installed. We just need to ensure proper positioning so that the cd tray does not knock.




A single tube socket was used. The existing hole on the side of the chassis was just nice for the job. No drilling needed.

Signal tapping from DAC. Notice the un-soldered holes. The blue dots represent the left and right channel direct out.




Resistors labelled RD21 and RD22 was lifted. Later, I soldered a 1uf Philips Orange capacitor as the coupling cap.

Several Hrs later:

The sound transformation before and after mod is really amazing one just don't need to sit down seriously to listen attentively.

Just playing the 1st few seconds of a familiar track even before sitting down already made my eyes go .

1st impression is Dynamics Dynamics and Dynamics. Unlimited of it.

Then comes the seductive vocals that valves do best.

Finally the treble texture changed from grainy Opamp's signature to sweet velvet smoothness.

Overall sound and tone is more towards the sweet crystal clear type rather than the warm mellow vintage type.

cheers.