HEEELLLLP - HDCD Filter PMD200 - INFO

[ThorstenL]

Konnichiwa,

Well, it finally is unbearable. The desire to tweak my Shanling CD T-100. And I mean with more than just OPA627 plugins.

I have pretty much decided on what do around the DAC's and in the analog stage. Yet there remains a little problem. The stupid HDCD Filter.

What I need to know, does the PMD200 retain the "Hack" option to kill the on Chip (digital) 6db attenuation for the non HD CD's? If so, how to access? Has anyone got a datasheet (I have the one for the PMD100, but the differences appear large enough that this is useless)?

Sayonara

[Cobra2]

Hi!

It seems that a pin called "GAIN (Pin 96)" is the Gain-Scale-Control;

"Gain Scale Control (output) – GAIN will go LOW for non-HDCD
recordings, and HDCD recordings that do not use peak
extension. GAIN will go HIGH for HDCD recordings that use peak
extension."


Arne K

[Pedja]

I think it won’t be a problem to set it the way you want. The datasheet is here.

Pedja

[Peter Daniel]

I suspect you've already seen this: http://www.6moons.com/audioreviews/shanling/T100.html

[ThorstenL]

Konnichiwa,

First thanks to all helping to locate the PMD200 Datasheet. Looking at the schematic of the CDP, the F*#%$£$ Filter is under software control and the signal is routed through the F*#%$£$ CS8420 even with upsampling off and the is too under software control.

Looks like I'll be connecting the PMD200 directly to the decoder with a reclocking daughterboard inbetween. Has anyone got a daughterboard PCB for 4 X 74AC74 and so on plus clock input (or on board KC7 or the like?). Then I can place the Digital Filter into hardware mode and take control. Why, oh why did it HAVE to be a 100 Pin SMD Chip with minimal pin pitch. I hated those even in the days when I still was fixing gear on a day to day basis.

Anyway, that is for another day.

In case anyone is interrested what I have in mind for the Shanling player, It has four 396A/6N3P Valves on 2 PCB's set up as parallel "Bootstrap Followers" two for the "tube" Outputs and the other two feeding the headphone Outputs. Cutting a few tracks and adding a few bridges will turn each PCB into a Parallel Mu-Follower with an output Impedance in the 200 Ohm range, a gain of > 30 and < 0.02% THD (mostly 2nd harmonics) at 0dbfs. Simply add a 75 Ohm Resistor across the lower Input sections grid and connect to the DAC.

Voila, no more Solid state after the DAC and it should sound nice enough. I'll also rebuild part of the Tube section PSU, but it is already reasonably competent in execution anyway. I have the prerequisite WE 396A for Audiophool cachet (and incidentially good sound) around and a pair of Jensen Copper Foil PIO's that I have been saving for exactly this kind of project.

Originally posted by Peter Daniel
I suspect you've already seen this: http://www.6moons.com/audioreviews/shanling/T100.html

Yes, I do however feel that T-100 (as good as it is) is fundamentally compromised by design, so just dumping a truckload of designer parts will only go so far.

Sayonara

[hifi]

I belive Elso sells such a reclocking board but, meassurments presented in this thread

Asynchronous reclocking

(witch I just saw you had commented in)

reveal jitter of about 10nS

/ Mikael

[ThorstenL]

Konnichiwa,

Originally posted by hifi
I belive Elso sells such a reclocking board but, meassurments presented in this thread

Asynchronous reclocking

(witch I just saw you had commented in)

reveal jitter of about 10nS

Elso's "board" is ASYNCRONOUS reclocking and he only offers (fro free) a clock design. Being lazy (and wanting to modify at least halve a dozend Shanlings) would like a ready made board, with 74AC74 to re-clock all lines to the dac's SYNCRONOUSLY and send the clock back to the Drive controller. If this is implemented well jitter will be << 100pS.

Sayonara

[hifi]

You could ofcorse use it Synchronos by feeding it with a Synchronos clock, but i do believe his board only have space for three 74*74.

A quick hack in eagle and www.olimex.com could get you a set of boards you require. I cant remember seeing a 4x 74*74 board anyway ,(


/ Micke