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Fred come on

Fred,

First there is no jitter in the data transmission from the computer to the dac in any interface other than SPDIF.

Ok so we have that established... Adaptive be it the Firewire or the USB method adds jitter because it has to change the Master Clock to assure the buffer to the Codec port (I2S, LJ, RJ, DSP whatever) has enough data to make sure it does not under or overrun causing pops and cracks.

Async mode is basically two types;

1) Simulated DAC interface using a device driver to make either USB or Firewire look like a dac and assure the buffers are supplied so there are no over underruns.

2) System device drivers for Asynchronous USB (Firewire does have this mode but no OS supports it) were all the OS's have support for it.

Ok so with Adaptive interfaces the jitter is very high usually from 1800ps to 4300ps. Any device using this technology better have some jitter reduction. BUT!!!!! as I said before these act like filters and cannot remove everything.

Short story a company at RMAF asked me to stop by their suite because they were interested in my technology. So I stopped by with Dustin Forman who designed the ESS Sabre32 dac chip. They also use the Sabre dac and was telling Dustin that they had less than 2ps of jitter. I said well the PCM2706 typically has about 3300-3800ps of jitter in I2S output and even more using the SPDIF output. Dustin immediately said there is no way we can remove that much jitter.

Anyways... back to the subject. Ok so with any Async method you can use a really low jitter master clock and derive all the Codec interface signals (again I2S, L/RJ DSP whatever). Heck you can even blow Dyna's horn and use a freaken atomic clock for that matter. At that point the I2S is derived and the intrinsic jitter (that created by the conversion of USB parallel data to serial) can be kept to a very low minimum. Therefore there is no reason to have jitter elimination as there was such a minimal amount from the beginning.

Fred... also your an engineer... how they making the XLR 110 ohms?

Thanks
Gordon
J. Gordon Rankin

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