External clock oscillator

External Clock for jitter reduction

In this section it is explained how to enhance the CD-PRO2LF with an external clock circuit. It is the 8.4672 MHz version clock. See or well priced overall solution.

There are 2 basic functions performed by the external clock PCB, hereafter called XO3 PCB.

1. Low jitter special system oscillator (manual trimmed to lowest noise level) ( active at the input side of the system)

2. Re-clock circuit for SPDIFF offering a re-clocked low jitter SPDIFF output. (active at the output side of the system)

In order to achieve the above the PCB has it’s own special power supply including regulation and noise reduction on board for the XO3 circuits consisting of the low jitter system oscillator and the low jitter re-clock circuits.

The XO3 PCB is designed by Guido Tent an experienced designer of High End electronics. For further details and email please look at the TENTlabs website found here .

It works the same for the PRO2 as this unit makes use of the CD-10 chips and the same x-tal as the PRO2LF.

Pictures are only for PRO2LF

A CD-PRO with CD-7 chipset or CDM12 industrial with CD-6 chipset can’t be upgraded this way.

Additional NOTE: hooking up DA converters with a 11.xx clock to CD-PRO2 or CD-PRO2LF is not supported or even technically simply possible. CL16 is available

Unfortunately the CD-PRO2LF was not intended to be used by an external clock circuit but can be modified in order to be able to deal with an external clock.

The modification is however irreversible as the system x-tal of the CD-PRO2LF will be removed in a destructive manner. It is done in this was because removing the x-tal by means of hot gas soldering or a normal soldering iron may cause damage to the 4 layer PCB thus destroying the whole PRO2LF. Therefore the below described, not so elegant but highly effective method, is the preferred method for the modification.

In case you need to REVERT, well, we have spare normal x-tals of the correct version, if really needed.

Any handling of or modification to the PRO2LF is totally at the customers risk. The advise given does imply any guarantee for good results. The pictures shown, only cover the PRO2LF

To the hands on pages with instructions

XO mounting instructions

The following wires can be identified:

· One single red wire on the left hand side for V+

· Twisted pair of white/black on the left hand side being the re-clocked Spdiff output.

· Twisted pair of yellow/black on the top side being the Spdiff input.

· Twisted pair of purple/black being the low jitter system clock output.

Note: The V– comes via the black wire of the purple/black pair. It should only be connected to the indicated point on the CD-PRO2 PCB and not direct or via a separate wire to the ground or other grounds.

VAU1254 CD-PRO2LF latest version