30 Leds VUmeter 1dB step.

[vmsa]

Hi!
Is a pleasure to read your comments.
Thanks JimB, I didn't know this IC, I will get one to try it.
But I can tell you that I used an AD536 in a prototype that I called LUmeter, using my display design (its the next step in loudness metering), and is working pretty good.

Audioguru, from my point of view, the 1dB resolution is perfect to see the envelope of the music, or to compare the balance between two channels, like with a needle meter.
I use average (or better, rms metering), not peak (as is seen in the common designs).

Sincerely,
Victor

 

[vmsa]

VMSA Got a question.
You moved the reference by 1db each for the three LM3915s. That fixed the top end, but I think you need to move the "ground" end by 3db also. If not the three meters will be at the same level at a low end reading.

Yeah!,
This is the trick, the voltage at pin 6 determine the maximun level, falling 30dB after the ten LEDs. Then if you got, for example, 1.228V reference in the first IC, the you need 1,378V (+1dB) in the second IC, and 1.546V (another +1dB) in the third IC. (if you know the LM3915 it is made with a resistor in the pin 8). Each LED in an 3915 is displaced 3dB, but it's displaced 1dB and 2 dB with respect to the others ICs, then a "wiring matrix" in the display, light the LEDs in the correct position. Believe me, it works !!!
Sincerely,
Victor

 

[4pyros]

Yeah!,
This is the trick, the voltage at pin 6 determine the maximun level, falling 30dB after the ten LEDs. Then if you got, for example, 1.228V reference in the first IC, the you need 1,378V (+1dB) in the second IC, and 1.546V (another +1dB) in the third IC. (if you know the LM3915 it is made with a resistor in the pin 8). Each LED in an 3915 is displaced 3dB, but it's displaced 1dB and 2 dB with respect to the others ICs, then a "wiring matrix" in the display, light the LEDs in the correct position. Believe me, it works !!!
Sincerely,
Victor

Do you have a diagram for this?