Clock change in Home Theatre processors

[stef1777]

I've read plenty of thread on CD or DVD reclocking but nothing on Home Theatre processors.

Can we have an advantage to replace the crystal in this kind of products?

I personally opened my own processor. All the system contain only one crystal (24.5760 MHz) connected using the standard way to the clock input of the DSP.

Any idea on this?

[stef1777]

Nobody have someting to write on this?

[Eric_R]

Since the crystal has no jitter it is the most optimal way, if you replace it with an oscillator you can not gain anything.
You can not change the frequency anyway since the processing, filters etc depend on it.
What you can do is improve the decoupling capacitors for both digital and analog circuits, mayby change voltage regulators.

[Guido Tent]

Originally posted by Eric_R
Since the crystal has no jitter it is the most optimal way, if you replace it with an oscillator you can not gain anything.
You can not change the frequency anyway since the processing, filters etc depend on it.
What you can do is improve the decoupling capacitors for both digital and analog circuits, mayby change voltage regulators.

Hi

Crystals do not jitter. Oscillators do, and they can certainly be improved.

regards

[stef1777]

A sample, for this topic.

My processor use an CS4226 coupled with an CS49300 serie DSP, both chips from Cirrus Logic.

The clock is very basic. Look at the schematic.

[Guido Tent]

Originally posted by stef1777
A sample, for this topic.

My processor use an CS4226 coupled with an CS49300 serie DSP, both chips from Cirrus Logic.

The clock is very basic. Look at the schematic.

so.....

Guido

[stef1777]

Hi Guido!

My question is still the same...

With this kind of chips as the CS4226, is a more precise clock an advantage and why if yes?

I've read the CS4226 datasheet. This is not clear inside if an external clock can be an advantage. They wrote that one external clock can be used in place of the crystal but do not specify specs for this. Same for the crystal, they don't specify the specs.

[Guido Tent]

Originally posted by stef1777
Hi Guido!

My question is still the same...

With this kind of chips as the CS4226, is a more precise clock an advantage and why if yes?

I've read the CS4226 datasheet. This is not clear inside if an external clock can be an advantage. They wrote that one external clock can be used in place of the crystal but do not specify specs for this. Same for the crystal, they don't specify the specs.

Hi

You shouldn't look for clock precision, but for lower clock jitter.

No personal experience with the 4226, but in general lower jitter helps. Most important is the conversion clock jitter at the DAC chips.

cheers