effects box digital IO

[Ray Peck <rpeck@PureAtria.COM>]

>>They could supply the effects in/out as digital s/pdif, which wouldn't
>>add much to the base cost.  You could go right through an effects unit
>>with digital in/out, and they could sell an add-on A/D D/A box for
>>people with analogue effects that want to use this technique.
>
>sp/dif means two extra ic's, neither of which are very cheap, two extra
>connectors and rear panel space, extra board area, clock oscillator, and
>various passive components. On a low volume product, (anything in the 
>music
>industry is low volume) this can mean adding anywhere from $40 to $80 to
>the list price of the product. Most effects boxes don't use digital audio,
>those that do are mostly high-end and use aes/ebu (sp/dif is a consumer
>format), which is more expensive. Big hit for something that 99% of the
>current market will never use. See how hard this stuff is? Its a wonder
>anything gets made....

Having done CPU design in a previous life (it's in the Sony
Playstation), I think I know what this takes.  If you're doing your
own processing ASIC as I understand Digitech does, for example, adding
s/pdif would add a very minimal amount of chip area, and only two
pins.  Testing for this kind of serial protocol would also not be too
difficult.

But OK, if you're not building a custom ASIC, it might be harder.
However, there are other solutions.  You can bring out a proprietary
ribbon-connector cable on the back panel, and sell a s/dif aes/ebu
convertor seperately.  This feature would add minimal cost, and would
allow you another point with which to hype the product.  If a company
made a series of effects boxes with this sort of
proprietary-but-convertible digital interface, they'd have a lot to
tout, and would tend to "lock" people in to their product lines due to
better performance.