"Mike Rivers" wrote in message
news:znr1059141895k@trad
In article
writes:
why does everyone insist on making excuses for a poorly designed
overhyped product that requires special "understanding" to get
basic utility out of?
Why do some people insist on applying what they know about one product
to another product and then say it doesn't work for them? You
continually suggest that there's a standard for console design to
which Mackie doesn't adhere. What is this standard?
I know of none, and I've looked for it. Maybe there's one buried in the
SMPTE or EBU someplace. One might be able to derive something from the AES
standards.
http://www.aes.org/standards/b_pub/a....cfm#standards
http://www.ebu.ch
http://www.smpte.org/smpte_store/sta...=smpte&scope=0
It would indeed be nice if one design criterion for a console is that
all channels operating at their 0 VU level could be summed without
overload, however look at how you'd have to design it. If you take the
simple route and say that each operating channel added to the bus
increases the summed level by 3 dB, and that sometimes you'll only be
needing one or two or six channels, you need about 90 dB of dynamic
range in the summing bus. It's not impossible, but it's not cheap.
This issue relates to something as basic as the assumption of how much the
bus output increases as operating channels are added. If you presume
uncorrelated signals then its 3 dB for the first channel added. If you
presume correlated signals then its 6 dB for the first channel added and
proportionately more per successive channel that is added. It's the
difference between a geometric sum (square root of sum of squares) versus
and sum in regular linear arithmetic.
Reading George's post, he seems to be saying that he judges how a console
works with a correlated signal applied to every input.
In that case, the bus output increases in accordance with regular
arithmetic. IOW he appears to be judging a console by what happens if you
take a signal generator and apply it's output to every input, and setting
every fader to zero dB.
Of course this is not how consoles are used in the real world. Consoles are
almost always used with uncorrelated signals that sum up geometrically.
Levels build up slower with geometric summing than with regular arithmetic.
We (as engineers) deal with this by simply reducing the level going
into the summing bus by trimming all the channels by an appropriate
amount.
Well, I think it depends on what kind of engineers we are.
I can definitely see someone testing a console with a signal generator, and
applying the same input to every input to see what happens. On the face of
it, this might seem like a reasonable thing to do. Some may even find it
surprising to hear that this is NOT a reasonable thing to do.
Coming up with 32 uncorrelated signals is not trivial, and analyzing the
performance of a console that is processing 32 uncorrelated signals is an
interesting technical challenge. I don't think there are a lot of people who
have tested consoles with 32 uncorrelated signals.
OTOH, I don't think there are a lot of people who have operated consoles in
practical use, with 32 correlated signals. Using a console with 32
correlated signals makes no sense at all in the real world.
Most audio signals in a studio are statistically speaking, uncorrelated. OK,
they may get loud and soft together, but their relative phases and
amplitudes vary greatly at any instant in time.
A good engineer will have a sense of what will be going into
the mix and start pretty much at the right place. It works on any
console, even a Mackie.
I can see someone who is very thorough and methodological testing consoles
with a signal generator and being dismayed with a console that clips in that
kind of a test. If they've been making decisions based on this kind of test
for years, I think it might come as a shock to hear that this is an invalid
test.