accessible metering for digital audio

From: Richard Webb (elspider@interl.net)
Date: Tue Oct 27 1998 - 16:06:05 PST


Hello,

AS an audio professional, I've found myself lacking any way to monitor
levels of program once it enters the digital domain. Yes, I can set
my gain staging so that a 1 khz sine wave at 0 vu is 18 db below full
scale. STill, I must hope evrything stays the same there through my
normal workaday life, as I don't always have a sighted assistant
handy.

There are many high quality products available to the sighted audio
professional for this purpose, but adapting digital metering isn't as
smiple I"m sure as the familiar vu meter. I've opened up discussion
with a person at Mytek digital and reproduce some of my thoughts to
him below.

I'd like to hear feedback from others who might find such a tool
useful. He says his company is interested in considering our needs in
future designs. If anybody else has input, write me or contact
Mitchell yourself.

REgards,

Date: 10-27-1998 12:04:53
To: michal@mytekdigital.com
From: elspider@interl.net
Subject: Re: digital meter adaptations
  
Hello, and thanks for the response.

On 1998-10-25 michal@mytekdigital.com said to elspider@interl.net
>Thank you for making us aware of the issue. The current DDD603
>digital meter cannot be easily modified for this task as it's
>pretty much a closed design with no space left. We have however,
>further development coming up next year and would like to look into
>possibilities of satisfying your requirements. It seems to be an
>easy task for a software based meter, a little more difficult for a
>hardware based. Could you please suggest how such a meter should
>work in your opinion?
Here's how my analog system works. I can monitor four channels of
audio, not simultaneously, of course. I suppose this could be
accomplished, using a separate tone for each audio channel. IN fact,
one place I worked a few years ago did a custom system this way, but
customizing systems isn't workable for the roving freelancer.

Once I've selected which channel I'm monitoring, I can set the signal
level at which I want the indicator to sound anywhere between -20 and
+8, now this is your standard vu. It accomodates your +4 and +8 for
pro and broadcast use. CAn be hardwired into a system or used with a
mult from your patch bays. I do the latter.

A selectable level at which one can get an indication of the level
being reached is really what I'd need. An indication at -18 dbfs
would be nice, as it seems to me it's become a production standard
(0vu = 18dbfs.) Of course fs, and maybe -6 and another.

Daisy chainability is nice with some analog vu metering that's been
adapted for audible indication. Mine isn't that I'm using presently,
hence the necessity of a mult. Your current metering already has this
capability I'm sure. I'm not familiar with all the technology,
I'm an appliance operator of this stuff for sure.

I'm glad you've shown some interest. A port off your current metering
designs would maybe be the idea, where at a certain level a voltage
appears at a jack or something. This kind of open ended design would
let those of us who have a little homebrewing capability do what's
necessary. The level at which a voltage appears at that port should
be user selectable easily. A user who needs audible indication of
some type could roll his own fairly easily this way, and it may even
find other applications. I've had sighted people in the business
state that an audible indicator might be handy during some sessions.
This would add little to the cost I would think, and anyone needing
such a modification could perform it himself in the field without too
much trouble. While we're at it, make sure you've accessible
doccumentation, machine readable, especially ascii or the popular word
processor formats helps us out. Ocr's allright, but it's time
consuming and doesn't always do well with sorting text from complex
graphics. A little doccumentation on how the port works, and even the
appliance operator with a fairly decent project studio could find a
local tech to build his own gizmo to interface with the meter.

This also puts the switching of channels at the gizmo end instead of
your end. Asighted person uses the meter in the normal way, where
those of us who need or prefer an audible indication just wire up an
oscillator to the port, set the level at which we want a signal at
said port, and we're up and running with adequate feedback. Right
now, I can run with analog vu, but once we go through a/d conversion,
I'm flying blind. Hopefully, nobody's fooled with anything in the
chain since a sighted assistant and I set up the 0vu = 18dbfs.

<<<End of excerpt>>>-----

Richard Webb

Electric Spider Productions
Usenet spambuster, replace any characters before the at with elspider
'There exist in many parts of the world societies in which food supplies
are short, where gathering sufficient food is a daily concern. These
societies still have music. From this we can only deduce that music is as
important to life as food.' Alan Bush




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