Author Topic: I2S Reclocking Line Driver  (Read 2737 times)

Offline zenelectro

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I2S Reclocking Line Driver
« on: August 25, 2015, 01:53:11 PM »
Hi All,

Well I finished latest zenclock installation and decided to go a step further and install an I2S reclocking / driving board.

When installing any clock in a CD94 (or similar), so far the best implementation is to feed the clock into SAA7210 chip (A chip?)
bypassing the SAA7220 (oversampling filter chip) altogether. This is what Steve, Rawl and others are doing.

The bottleneck then becomes the 7210 chip that generates the I2S stream. It corrupts the nice clock timing and adds noise / jitter.

The reclocking board takes the 3 x I2S signals from 7210 output and re-aligns them with the clocks super tight timing.

The results are very dramatic and possibly biggest change I have heard so far. First listen showed mostly very good but also some slight detrimental effects.

However the I2S board also has provision for shaping the wave (speed) and the level of the I2S OP. This has a dramatic effect on sound. The TDA1541 appears
to be -VERY- sensitive to the I2S signals WRT noise, speed and levels. Playing with these and finding sweet spot for 1541 is the key.

I'm currently playing with these and one thing is apparent - this is the next level of performance.

I also have a feeling that once the levels and speed are optimised for 1541 a proper shielded cable interconnect may well be the best option but that's just gut
feeling at this stage.


cheers

Terry
« Last Edit: August 25, 2015, 02:04:18 PM by zenelectro »

Offline zenelectro

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Re: I2S Reclocking Line Driver
« Reply #1 on: August 27, 2015, 01:39:50 PM »
Further work on zenclock / I2S reclock / driver board.

I've got this sounding really good now and have implemented some advanced trickery through lateral thinking. :)

There's a parallel development going on, both the Enterprise DAC and the transport.

DAC -> Upgraded the OP caps on DAC from Rel Cap Tin/PP to Mundorf Silver/Oil Supreme. Big difference - fog lifted but musicality and timber still good, maybe even better.
Duelunds are in my future but they'll have to wait for $. Next I'll get some Shinko's for the OP and a few Allen Bradleys. Chokes also need to be replaced with something
better. I'm actually surprised how good the DAC sounds, yet it still has a lot of room for improvement.

Clock / I2S -> This where a lot of the action seems to be. I've done a lot of playing with OP resistors, wave form (super sharp / rounded off) and wave levels.
So the trickery is that we all tend to use whatever OP resistor (47R / no R) on all 3 I2S signals but I had a good think about this and the fact is they are 3 different
signals (sample clock / word clock / data) and they can be treated differently according to their purpose in the DAC. That's all I'll say at this stage.

Fun and games.

cheers

Terry

Offline zenelectro

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Re: I2S Reclocking Line Driver
« Reply #2 on: August 27, 2015, 01:42:08 PM »
PS, I also need to use better wire in the DAC.

Will have to try either that cotton covered copper that Oz has used or some foamed dielectric UPOCC (whatever its called).

Offline matt200sr

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Re: I2S Reclocking Line Driver
« Reply #3 on: September 13, 2015, 08:52:09 PM »
Up and running Terry thank you once again Awesome work!


« Last Edit: September 13, 2015, 09:37:33 PM by matt200sr »