Question for Experienced Hardware Techs - How Much Difference Was There Between Individual Channels in Classic, High-End Consoles?

[JohnRoberts]

It's been too many years, but I seem to recall the Otari Concept One desk meters had 1/4 dB steps just above and below 0 VU.

Bri

I've killed way too many brain cells over the decades designing and thinking about meters. I even made one 100 segment vacuum fluorescent meter back in the 80s but even that one used 1 dB steps. I was an active proponent of simultaneous peak/VU metering so by using a evenly spaced dB scales one can impute the crest factor (ratio of peak to average) by inspection. The number of LEDs between peak and VU, times dB per step gives you the crest factor.

For any challenged by lining up (zeroing) a console with coarse LED meters, you can add resolution to any step size meter by alternating between two precise level audio input signals. For example say you alternate between an exactly 0VU reference tone, and one that is say 0.1dB quieter. You could then calibrate the LED meter to light when the 0VU signal is present, and not light for signal 0.1 dB below 0VU.

JR

 

[Gold]

For any challenged by lining up (zeroing) a console with coarse LED meters, you can add resolution to any step size meter by alternating between two precise level audio input signals. For example say you alternate between an exactly 0VU reference tone, and one that is say 0.1dB quieter. You could then calibrate the LED meter to light when the 0VU signal is present, and not light for signal 0.1 dB below 0VU.

JR

Adding a lamp that lights at exactly 0VU on a meter panel would be a nice addition. What circuit would light a single LED at a very specific level?

 

[user 37518]

Adding a lamp that lights at exactly 0VU on a meter panel would be a nice addition. What circuit would light a single LED at a very specific level?

A window comparator maybe?

 

[JohnRoberts]

Adding a lamp that lights at exactly 0VU on a meter panel would be a nice addition. What circuit would light a single LED at a very specific level?

a one LED meter? Back when I was putting VU meters on consoles (the customer is always right), I would add a red LED by each VU meter to indicate peaks that the VU could not see.

I designed one console back last century that only had a handful of full meters in the meter bridge, but multiple alternate audio paths inside the console. My per path metering was a single bicolor LED for pretty much every audio path. It would light green for signal present around -20 VU, and red at 6dB below clipping to warn about headroom. These bicolor LEDs were very useful to confirm where signals were and how hot they were, without tens of full meters cluttering up the scenery.

JR

 

[Gold]

a one LED meter?

Not a meter, an indicator. Like an overload light indicator except this is a “calibrated within 0.1dB” indicator.

 

[JohnRoberts]

You could make one to indicate "calibrated within" using two comparators so one turns on at 0VU and the second turns the first off at +0.1VU (aka window comparator).
===
Back in the 80s for a kit design (CX record decoder) that needed to use calibrated playback levels to decode properly, I developed a different bicolor LED indicator where a red and green LEDs were driven from the two collector current outputs from a LTP (differential two transistor pair ). If audio level was below threshold only the green LED was lit, for above threshold only the red was lit. Exactly at the threshold both colored LEDs were lit. The LTP shifts current from one device to the other dramatically from only a several mV difference at the bases.

JR

 

[Gold]

You could make one to indicate "calibrated within" using two comparators so one turns on at 0VU and the second turns the first off at +0.1VU (aka window comparator).
===

Thanks, ill look into that. Sometimes the dreaded parallax is unavoidable.

 

[Michael Tibes]

Neve 5402 CRC Console documents - there is link to a wetransfer with a manual of a Neve boadcast console. It seems pretty complete a first glance, also including the final check measurements from the factory. Maybe this shines a light on what technicians focused on back then.

Michael

 

[JohnRoberts]

Perhaps make one using a magic eye tube....magic eye tube....

 

[pucho812]

Absolutely agree, I can't believe that plug-ins like these are now a thing, after decades of audio design new BS still comes out every day! it shouldn't surprise me....

Whenever I hear something like "organic and less sterile" I immediately know its something that the Marketing department created.

And yes, most analog consoles have differences between channels, it is not something desirable if you ask me....

Whats next?

I have an idea:

"People back in the 60's and 70's used to smoke in the studio, this created a thin layer of nicotine and tar on top of the circuitry, faders and pots, which made the equipment sound more 'musical' and 'upfront' giving it that old school vibe, which is why with the help of our friends from Phillip Morris we modeled this effect with our advanced 'Marlboro Convolution System' (MCS)"

Perhaps I should put that in my CV and apply for a job at Brainworx

Walter sear at sear sound smoked like a chimney stack. When he wasn’t in his office smoking, he would be walking around doing whatever and smoking. He would ash in his hand to keep things tidy. One day I asked him about the large vintage mic collection and all the smoke and he tells me “it adds a layer of protective coating” I didn’t ask about it any further