VU Meter - Info Requested
c23...@kocrsv01.delcoelect.com
I am looking for a schematic (or commercial availability)
for a VU meter that can handle both microphone level and
line level inputs. Ideally, the device would reference 0dB
to maximum mic level in the microphone mode. It would reference
0dB to maximum line level in the line mode. The device could
pass the input signal thru (in-line meter), but this is not essential.
Input impedances in the two modes should be representative of a
microphone or line level input in the respective modes.
Thanks in advance for your assistance. Please email or post replies.
Eric Mumford
circuitry and I haven't seen them around.
eric
--
Eric Mumford Electrical Engineering, Rensselaer Polytechnic Institute.
mum...@rpi.edu "I love me, yum yum doodle dum!" -Baloney
Richard D Pierce
John Lundgren <jlun...@news.kn.PacBell.COM> wrote:
>
>Eric Mumford (mum...@magritte.its.rpi.edu) wrote:
>: Where can I get level meters? I'd like to build some audio-line monitoring
>: circuitry and I haven't seen them around.
>response to the audio so that they could read the peaks. That's one
>thing that made them expensive, at least for the accurate ones. I don't
>know how this is simulated on the newer LEd bar displays.
First, the guy asked for level meters. VU meters are one kind of level
meters, but not all level meters are VU meters.
Secondly, the mechanical ballistics were designed so that the meters DID
NOT respond to peaks in a predictable fashion. Since the meters couldn't
possibly accurately respond to peaks, the inability to do so was
standardized.
--
| Dick Pierce |
| Loudspeaker and Software Consulting |
| 17 Sartelle Street Pepperell, MA 01463 |
| (508) 433-9183 (Voice and FAX) |
James Addie
>In article <3el6pk$u...@usenet.rpi.edu>, mum...@magritte.its.rpi.edu (Eric
>Mumford) wrote:
>>
>> Where can I get level meters? I'd like to build some audio-line monitoring
>> circuitry and I haven't seen them around.
>>
>> eric
(snip!)
>If you just gotta have that look and feel of old analog VU meters, it's
>usually not too hard to scrounge them up in the surplus market. I'd
>recommend looking for old Simpson, Western Electric or Modutec (AC version)
>VU meters; don't bother w/ meters out of most consumer recording equipment,
>as they usually don't conform to VU requirements even though they may have
>"VU" stamped on them. I don't know what levels you'll be measuring, or
>what the circuit impedances you'll be dealing with, so you *might* want to
>consider a buffer amplifier with the analog VU meters.
Of course, there have been no true VU meters (meter, rectifier, pad,
buildout resistor, all inclusive) sold for years.
The meter movement and rectifier is
available from Modutech or Selco. I've seen Modutech (sp?) meters in
blister packs in electronics stores-even the VU meter scale. Selco
advertises there meters in broadcast trades. They also make a PPM.
--
Jim Addie "Snakes! Why did it have to be snakes?"
AddieTech, Inc. "Asps. Very dangerous. You go first..."
N9SSD
Scott Dorsey
>
>Of course, there have been no true VU meters (meter, rectifier, pad,
>buildout resistor, all inclusive) sold for years.
>The meter movement and rectifier is
>available from Modutech or Selco. I've seen Modutech (sp?) meters in
>blister packs in electronics stores-even the VU meter scale. Selco
>advertises there meters in broadcast trades. They also make a PPM.
Huh? Simpson has them in the catalogue, copper oxide rectifiers and
everything, just as in the WE standard. I bought a bunch of them to
replace damaged ones in an old Collins mixing console.
Note that if you bridge them across a 600 ohm line as the standard
implies, you'll induce some amount of distortion in the line due to
nonlinearities in the rectification. Bridge a 600 ohm resistor across
them, and use a dedicated drive amplifier for them. (This is a big
deal for a tube unit, but in this day of cheap op amps it shouldn't be
a problem for anyone).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Greg J Szekeres
->DPi...@world.std.com (Richard D Pierce) writes:
->
->>First, the guy asked for level meters. VU meters are one kind of level
->>meters, but not all level meters are VU meters.
->
->>Secondly, the mechanical ballistics were designed so that the meters DID
->>NOT respond to peaks in a predictable fashion. Since the meters couldn't
->>possibly accurately respond to peaks, the inability to do so was
->>standardized.
->
->
->Interesting way of putting it! However, even in 1938, meters could have
->been made that were faster in response. The 300ms rise/fall time was
->chosen to have relevence in speech monitoring, and was agreed upon by
->both broadcasters and telephone companies. Broadcast modulation monitors,
->standardized later, have a much faster integration time, yet use
->mechanical meters.
->
->It's interesting to note how many meters are in use today that have a
->scale similar to the standard VU, but don't adhere in any way to the
->standard ballistics. Also interesting to note that by comparison, a VU
->meter has a better relationship to actual loudness than a PPM or True
->Peak meter. Each has it's purpose, but thay are hardly ever understood.
->
->Oh well.
->
->--
->Jim Addie "Snakes! Why did it have to be snakes?"
Anyone can impliment his own design and use it himself. If you take any
mechanical meter and practice with it you will become familar with its
balistics and what it represents. It would benifit to have some other
standards around such as an oscilloscope. Personally I would prefer both
instantanious and standard VU movements together in unison.
Greg Szekeres
David Coller
>I am looking for a schematic (or commercial availability)
>Input impedances in the two modes should be representative of a
>microphone or line level input in the respective modes.
>Thanks in advance for your assistance. Please email or post replies.
Look at Sam's audio publications especially Sound Sys Eng then buy a mic
preamp and line amp with bridging inputs to hook across the desired
sources. Use lab VTVM or equal to calibrate.
Dave
--
dco...@norden1.com