|
re .1 Todd, my tv's screw up my music recordings; the video is
ok, though. Does your midiverb really mess up the tv? I remember
once being able to mess up reception (tv and radio) by turning the
frequency way up on a square wave test generator.
I've got the usual: reel to reels, mixers, synths, and assorted
homemade gadgets. It shows up in anything real close to the TV.
re .2,3 Tom, thanks for the analysis of mumetal. Are you saying
then, that a thin sheet metal cabinet wouldn't be of significant
help? Even if grounded?
A 1" steel box isn't quite feasable but a fairly thick shelf (~�")
between video and audio might be.
What do pro monitors have? I've heard they're shielded better?
Fredric DVINCI::CERTO
|
| > re .1 Todd, my tv's screw up my music recordings; the video is
> ok, though. Does your midiverb really mess up the tv? I remember
You wouldn't believe the garbage that the thing generates, Frederic.
Thank god the neighbors have no idea. If you know anyone that is testing
for EMI and needs a good garbage generator, let me know. It's obvious
that the people at Alesis know that shielding with plastic is the cheapist
way out...
Todd.
|
| Electro-Magnetic Compatibility is a Digital issue, by the way. 5 years
ago we ignored the FCC regulations for our type of computer equipment,
but about 3 years ago went into a panic to comply. The strategy was
designed to avoid shaking up the whole product line. First, try to make
a cabinet that could attentuate radiated Radio_frequency interference made
inside the cab and suppress conducted RFI (i.e., going into the power grid
through the power cord from the computer). They came up with guidelines
for no bigger than 3-inch slots (a GHz attenna) on cabs, and RF gaskets,
and like that. Next, try to redesign boxes ( box is the thing that slides
on slides in a cabinet) to suppress interference. Strategize cable routing.
Put filters (caps to ground) on communication line bulkheads on cabinets
(comm lines aren't supposed just come straight out of the CPU box and out to
the world, but get plugged into a filtered connector mounted in a bulkhead.
Then, see if RFI could be suppressed at the board level with ferrite
beads on clock lines, and good routing of clock and counter lines,
and avoidance of Shottky TTL unless essential (obviously, almost the
whole 11/780 is Schottky, but never mind).
I don't know about Midiverb. I'd expect it to be the consumer class,
that is the toughest, tougher than the one VAXes have to pass in the
"bubble" measurement installation at Marlboro, MA. Maybe not. It's
expensive to get tested.
I think we're mostly on top of it now.
Tom
|