More about switching

[The Dark force of dance]

Y-ellow Juergen 'n' all.
        When it comes down to it. The best approach is to use a switch. Just
an ordinary, DPDT switch. A good looking one of course. Simple, cost
effective and pleasing on the eye.

But why do it the easy way when you spend hours of design time (which I have
a lot of at the moment) coming up with something that won't impress your
friends because they won't even have a clue how clever it really is. That's
what I love about people on these lists. We all appreciate the finer things
in life. :)

I just wish there was a cheap product like xilinx or altera that would
behave in the analogue world. It would then be a snap to design the entire
thing into a single chip and build a 100 channel mixer inside a matchbox. Of
course the sliders might be a little hard to grab without the aid of a
microscope but this is price we pay for progress.

Dreaming asside. That's probably a good solution to build up discrete OTA
type circuits. One could probably even use transistor arrays and get some
matching happening. I'd really like to do that and I can kinda picture a
lay-out but I think when it comes down to it, I'm also leaning towards
simplicity. This is one of those problems you'd wish would just go away.

I was thinking of getting one of those Berhinger MX2642 EuroRacks. Then
Modifying it so that it will fit in the rack the way I want it to. Not the
way some designer though would suit the lowest common denominator. Not that
I can afford one right now. But I thought If I just used one of them I could
save myself a lot of hassle. But when I thought about it later, I thought.
"What a crock. We're talking about 8 to 10 stereo pairs that don't need EQ,
gain, or even level adjustment. In fact once Trimmed, the level would never
need to be adjusted again. (in theory) All I need is a bit of switching and
raw quality. Hell I could just about do the whole thing passively if it
weren't for a little signal routing. And like Scottie's famous words in Star
Trek 3. "The more complex the pluming, the easier it is to stuff the drains."

The whole thing is competing with digital sources so it's got to be ultra
quiet. The thing that appeals to me though is that with VCAs of some kind, I
could use them like gates. Gating out any potential noise from any
potentially noisy source that I may potentially have connected at any
potential time. Ah! Decisions Decisions. And all the time I'm on the lookout
for a single chip that will solve all my problems at one time. Including my
cash flow problems. :)

As for cross point switches in a matrix. The app notes for the 74hct(insert
part number as long as your arm here) 8 by 8 cross point switch suggests
that this is possible. First of all it has 16 I/os any I/O can be connected
to any other at any time. All 64 can be switched on at the same time. You
simply address the point you want to switch and tell it to be on or off. And
of course it latches your command. I think if you put a resistor on the ins,
it will allow you to mix multiple ins to single outs. I seem to recall the
impression that this was the kind of thing it was designed for. I've only
used them to switch MIDI signals so I can't comment personally on this
aspect. However I've often wondered how they'd go in making an automated
patch bay. And I kinda recall some manufacturer selling a 16 x 16 automated
patch bay. I'd assume they'd use this, or some similar technology. It would
be nice to find out for sure. And for that matter I'm off to check out the
Harris page and see if they've put anything new up there that might be useful.

Thanks again.

Be absolutely ICebox.
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