Pro Audio Design Forum

Good to see some version back, if only in proto form.

Roger's gonna roll his eyes; I've said it privately enough times I'm sure: why does anyone need a 20 dB GR point on a meter? I'd always rather have great resolution near the threshold versus extended range. Once you're past 10 dB GR, the meter doesn't really matter any more. What goes on between 0 and -2 does matter a great deal to me, as it helps determine the best threshold. I am probably a minority.

why does anyone need a 20 dB GR point on a meter?

To prove it can go to "11?"

I do notice this GR has 2 dB steps which is cool.

Roger did you use a comparator string to get the 2 dB steps? Or just drop the intermediate steps on an LM3914 to make that jump from 10 to 20 dB?

I like the simple three-knob approach.

I do like those square LEDs.

The red hex screws are a nice touch.

Back when I designed dynamics processors (a long time ago), I oriented VCA status meters to indicate gain reduction going down, and gain boost up. Of course this was in an odd-ball full range compressor that boosted low level stuff that was below threshold, and dropped high level stuff that was above threshold, not too mention added parallel downward expansion/noise gating... and more, perhaps too much.

Your display effectively communicates how much the signal is squashed, with higher is more, all good. The customers generally like all blinky lights.

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Agreed the rectangular LEDs look better to me too...

The painted allen head screws are a nice detail but almost look like indicators. The rectangular LEDs reduce the potential for confusion.

JR

raf wrote: this meter implementation is one Doug suggested many moons ago. It uses a standard LM 3914 and skips the intermediate steps.

That's funny, I remember some angst over the options with a reduced number of LED's. Today I'd probably vote 1/2/3/4/6/8 or 10. Tomorrow?

I have been kicking around the idea of making an universal meter chip based on a microprocessor... It is almost easier to make a big meter effectively than a small one. The rap against the 3.3V micro family I like is that they don't look like they can drive bare LEDs adequately, but i suspect modern high efficiency LEDs could probably work. For large scale meters, simple to drive a latch IC.

While it is hard being all meters to all people, i could pretty easily support an optional linear scale, or even a proportional log scale where the step size between LEDs is read in from a pin. Say you divide the PS by some fraction and feed that into an A/D input. The micro reads that voltage, determines the ratio of the 3.3V supply, and makes that the ratio between each LED down as far as it can.. Easy to make 1dB, 2 dB, whatever dB steps down to the resolution floor of the A/D.

This us not worth killing a lot of brain cells over but i have a sweet PK/VU technology I have in the can to use. I'f love to make a generic swiss army meter (in my spare time)

JR.