Speeding up my Digital (mod advice needed)

[BobM]

I've begun the modification process on a Toshiba SD4960 universal player (CD, DVD-A, SACD, all but vinyl). Here's a link to my mods thread:

http://www.audiocircle.com/circles/v...ic.php?t=12613

As you can see, the mods had a very good effect, but there's one thing missing. The speed of the player is just not up to snuff. Those leading edge transient's are a bit flat - the crispness of the sound and such. Now it is very pleasing and forgiving, but so is my vinyl while still having that speen factor.

So, I'm looking for some suggestions on how I might mod this thing to get some of that speed. I'm sure it's got something to do with the digital circuit itself, perhaps an internal swirtch on the DAC chip, perhaps some cap that's loading the chip, perhaps something else. I do have a board schematic and the detailed paper on the DAC chip.

Anyone have any experience with this that may want to give me some suggestions on where to start (remember, I'm not an engineer so be kind)?

Thanks,
Bob

[Chris Daly]

Interpolation -to make more information up is
a good tool to achieve faster digital circuits.

There are a number of timing signals coming in and
out of Dacs , suggest you look up schematics to see
exactly what you are dealing with, in this Toshiba model

You should have LR Clk Left right Clock , Data , Bitclock
as inputs and usually current outputs requiring current
to voltage conversion ( I/V ). Some Dacs also have inbuilt
(I/V ) conversion but having choice here is a definiate plus.

Interpolation is achieved with flip -flops , I had a
article published in Electronics World in June 1997 exploring
how to overcome SPDIF. The method took aforementioned
signals -mentioned as inputs above, and reclocked
each signal with flip flops on transmission and reception

Complex , impossible to resell, but the sound is right.

Your thread mentions comparison to turntables, I recall
a comparison of my digital setup comparing to a high end
turntable preamp into Quad ESL63's The overall sound
presentation was identical using a Three Blind Mice
( japanese label )CD and LP of the same performance.
On closer listening my digital setup had better bass floor
and no surface noise.

A flip flop works by comparing a faster clock signal on
an input called Clock to the timing of input arriving on a
pin called data , if for instance you have a 16Mhz crystal
and a 2Mhz input you have gained an advantage in
theory of 8, by the timing of the Clock input.

The output of the Flip Flop runs outputs which are
inverted and non inverted - inviting balanced digital transfer
There are other housekeeping pins such as set and reset
that need to be attended to in each application.

Generally :
Oversampling chips have clock generation
pins that can prove useful to provide clock generation, Sony and other manufacturers will sell crystals as spares if you quote
a part number to them. look up the application data for Oversampling ics and find input for such crystals, then
find that ics clock buffered output.

Hope this helps Cheers / Chris



Complex , impossible to resell, but the sound is right.