Banner for Audio Level Meter article

Aren’t those blue level meters that you see on McIntosh amplifiers really cool? This article shows you how to build level meters for your system which do far more than even theirs do. The Audio Level Meter project gives you:

Pic of McIntosh MacMC-12Kb amplifier with blue level meter
  • 100dB Logarithmic decibel display so it can show the full audio dynamic range
  • Linear display to show music dynamics similar to a VU meter
  • Fast peak detect mode to identify when an amp will be clipping.

The huge dynamic range of its log decibel scale shows you everything from 500 watts RMS, down to less than one millivolt. It’s so sensitive that, when your amp is off, it shows deflections from conversation in the room as your speakers work like microphones! It shows the whole range, while maintaining a resolution of one dB.

Use peak detect mode to accurately detect clipping of even the shortest peaks found in music. Averaging mode lets you measure continuous power and noise.

The variable decay time control lets you set the meter to capture transients for accurate peak readings or to respond rapidly to show music dynamics.

Variable illumination lets you adjust brightness for varying residential lighting conditions (such as TV viewing).

The supplied files package gives you all of the graphics files needed to print excellent artwork for the PCB, front panel, meter scale and more. We’ve even included the original CorelDraw source files, so you can customize the project, if you like. Get the full article, schematic and files here (free!):

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Audio Level Meter article (3MB)

Front view of audio level meter
Custom scale for audio level meter
Inside, behind front panel of audio level meter

Front view of the Audio Level Meter

Custom meter scale

Inside, behind the front panel


Reader Comments

Posted by Steve L. April 11, 2012 - 07:12 am
Hi Dennis, I really appreciate your kind comments. All the best, Steve

Posted by Dennis April 11, 2012 - 12:16 am
Hi Steve,

Just came across your site while searching for manufacturers of custom VU meters & least to say was blown out with your work on the audio meter, and would like to say, thank you very much for shareing it.
It really goes beyond anything I've seen so far in term of features.

Again, Thanx.

Posted by Steve L. March 02, 2010 - 02:03 pm
For the poster regarding the electrolytic caps (Name?): Actually, two back-to-back polarized caps are the same thing as a so-called nonpolar electrolytic cap, so the circuit is okay as it is. Thank you for your interest, though.

Posted by   March 02, 2010 - 01:40 pm
Electrolytic capacitors don't like to see reverse polarity (they tend to spill their guts rather dramatically). Therefore, C2 & C3 (on the input) should either be a single nonpolar unit or each capacitor should have a (fast) rectifier across it to ensure they don't see reversed polarity. Assuming your target is 50uF total, each capacitor can then be reduced to that value.

Posted by Steve K. February 13, 2010 - 07:59 pm
I still think this is a really cool DIY project. Has anyone else dipped a toe into this one?

Posted by Steve L. February 10, 2010 - 10:22 pm
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