SPDIF or AES/Ebu interface

[Magnus Danielson]

From: buchi at takeonetech.de (Michael Buchstaller)
Subject: SPDIF or AES/Ebu interface
Date: Thu, 31 Aug 2000 15:38:33 GMT

> Hello Group,

Hallo Michael,

> i am in the process of building a tube-based DAC. First experiments with
> a 8-bit-version vonnected to a PC´s parallel ports look promising.
> 
> But i want to have a digital input via SPDIF (or the like), so i could connect a
> CD player or other gear directly.
> Having looked at various data sheets of SPDIF decoder IC´s, i am very
> confused. Is there anything out which would allow me to simply convert the
> serial data stream into a parallel one ? It seems that all the IC´s are designed
> to be interfaced to a MPU or at least to a DAC IC with serial input.

Yes, but then add a few chips to do the serial to parallell conversion. Since
quite some time has the audio/hi-fi industry been using serial devices since
it gives supperiour pin-count/function ratio. You can find very nice stereo
DACs in a 8-pin capsule for instance.

However, what I am woundering is really what the point is here... are you
really using tubes as the fundament switches of the D/A ladder?

I'm not a tube-head, but how well can one calibrate them as stable switchable
voltage or current sources? As you go for more bits this will become more and
more important since it causes distorsion, and not the kind of distorsion that
you are looking for.

Anyway, if this is what you are intending to do it certainly sounds like a
odd-ball project. It would be interesting to see how it turns out. Personally
I would stick with a commercial linear DAC.

> I would really want to avoid a provessor to do this task; any hardware solution
> would be preferred.
> Does anybody out there have experience in this field ? Specially,which decoders
> are working fine, and which ones are better avoided ?

Well, I would be looking at the Crystal Semiconductor ones to start with.

Cheers,
Magnus