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-   -   Using several buffer-stages in DAC (http://www.diyaudio.com/forums/digital-source/18328-using-several-buffer-stages-dac.html)

Lucas_G 29th July 2003 07:17 AM

Using several buffer-stages in DAC
 
Dear daccers,

After having done a lot of comparison on commercial CD-players, I have come to the conclusion that the elemination of jitter is one of the most important factors in attaining high-quality CD-sound.

Most brands seem to aim for preventing vibrations within the player and laser-unit. This seems not totally effective...

The one cd-player that sounded best of all, was a Meridian 588.
In this particular player, there hasn't been done much on the mechanical part. It doesn't have a heavyweight chassis.

However, Meridian just uses a CD-Rom reading unit and then feeds the data into three series of memory-units. Between those 3 stages the jitter is eliminated by re-sampling the data each time it flows from one stage to another...

The result is very good indeed. Even much better than all the Arcams I listened to.

Is anyone aware of a DIY DAC that uses such a strategy?
Could it be implemented in a DIY project?

Regards,

Lucas.

guido 29th July 2003 10:56 AM

Yep,

Put the clock at the DAC and feed it back to the cd player.
FIFO between I2S of player and DAC and voila:

Independancy from the transport jitter. Search way back here
in the digital section.

Not much progress from my side on it, currently looking for a ~1991 Marantz or philips with a lot of space inside to put it in
( i use the old 11MHz clockfreq).

GuidoB

fmak 29th July 2003 01:02 PM

Re: Using several buffer-stages in DAC
 
[QUOTE]Originally posted by Lucas_G
[B]Dear daccers,

After having done a lot of comparison on commercial CD-players, I have come to the conclusion that the elemination of jitter is one of the most important factors in attaining high-quality CD-sound.

-----------------------------------------------------------------
See my post on CD TRansport Experience. The transport matters too!!

Some jitter reduction devices don't sound right . The case in point is the Assembalge D2D which is sophiticated and measures well. After two years of listening to it and others, I have decided that it does more harm than good in really hq systems. Insert it into a poorer CDP and it seems to work wonders.

fedde 29th July 2003 01:41 PM

Here some nice marketing babble from Meridian ;)
http://www.meridian-audio.com/p_588.htm

"For high quality audio the final audio must flow very smoothly without jitter"
"Unlike other players that try to lower jitter by controlling drive vibration, the 588s triple buffer memory architecture abolishes this problem forever."
LOL

"ROM drives recover the data from computer discs perfectly. Loading a computer program rarely fails due to the ROM drive. Therefore, extracting the data from a CD can be done without error"
Not completely true. CD-ROM's have extra information for error detection and correction. Though reading the same data on an audio CD a few times can help...

The triple buffer idea is not so bad though. I was thinking about a similar thing a few days ago. The point is that the output of a reclocking stage is partly dependant on jitter of signals on the input (the supply will vary, or there is interference within the chip). By employing multiple stages these effects can be reduced!

Though zero jitter is an illusion of course...

Fedde

Guido Tent 29th July 2003 09:16 PM

Re: Using several buffer-stages in DAC
 
Quote:

Originally posted by Lucas_G
Dear daccers,

After having done a lot of comparison on commercial CD-players, I have come to the conclusion that the elemination of jitter is one of the most important factors in attaining high-quality CD-sound.

Most brands seem to aim for preventing vibrations within the player and laser-unit. This seems not totally effective...

The one cd-player that sounded best of all, was a Meridian 588.
In this particular player, there hasn't been done much on the mechanical part. It doesn't have a heavyweight chassis.

However, Meridian just uses a CD-Rom reading unit and then feeds the data into three series of memory-units. Between those 3 stages the jitter is eliminated by re-sampling the data each time it flows from one stage to another...

The result is very good indeed. Even much better than all the Arcams I listened to.

Is anyone aware of a DIY DAC that uses such a strategy?
Could it be implemented in a DIY project?

Regards,

Lucas.

Lucas

It is called reclocking. The final quality depends on layout, used logic family, spoewr supply and finally the oscillator used.

The principal is good. We implemented it in our DAC design, long ago.

Also Audio Inovations (Alto) did this

regards


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