![]() or not - but it would be up to the user to specify). and the cpu would do all the 'fades' that are needed (so if the signal suddenly dropped out, the user might want the meter to slowly sink down instead of dropping suddenly. ![]() you get some sampled audio that is smoothed with a cap and read that via the a/d port as fast as you can, then for each reading you apply the mapping (linear or non-linear probably via some lookup table to make it run faster) and then you come up with a resultant output voltage that gets sent out via another analog pin on the cpu, to the meter movement. So front-ending a physical meter movement with an arduino class cpu sounds entirely reasonable to me. ![]() How fast DO you have to change the needle's position in order to make a good VU meter? I'm not sure we can easily define what an ideal VU meter is, anyway its a meter, afterall, and if you wanted a peak-hold led display you would have asked for that (the OP would have). I've built a few power amps with LED meters way back when, but these days I just find that flashing lights distracting. LED/fluorescent bar graph meters don't have to deal with a mechanical moving mass, so the attack/decay times can be controlled easily with electronics, and the dynamic range issue is also easy if you use the right chip/circuit to drive it (and have enough segments to give adequate resolution). Back in the late '70s and early '80s there were a number of commercial amps with comparable analog meters (until LED or fluorescent bar graph meters became popular). I've yet to see any DIY amp with an analog meter that sophisticated (I'd like to be proven wrong, though - and am especially interested in knowing what meter mechanism is used and what circuit is used to drive it).ītw, McIntosh is just one example. So they are peak-reading meters that could actually register music transients, rather than the ballistics of ordinary VU meters that could only show average levels. Not only that, if you have actually seen these meters in action you'll notice that they have a very fast attack time but slow decay. Now, THAT meter will show something from pianissimo to fortissimo!Īn analog meter like that could only be achieved with a special meter drive circuit that has compressive gain. McIntosh | Power Amplifiers/Integrated Amplifiers Notice that the meter on the 1200W monoblock McIntosh MC1.2KW amp, the meter has almost 60dB of range: ![]() If you crank up the sensitivity of the meters to show movement at low/mid volumes, then the meter would simply peg on the right hand stop when the amp is called upon to deliver more of its power (not to mention that the meter then ceases to "measure" anything meaningful). On a conventional analog "VU" meter, the meter needle would hardly move when the amp is putting out 1.8W, and that's usually already a fair amount of sound pressure level on most speakers. Let's take the β24 as an example, 0dB would be around 180W into 8 ohms. They have an extraordinary dynamic range, much more so than the typical "VU" meters that could typically manage only about -20dB to +3dB.įor a meter to be of practical use (rather than just as visual amusement), 0dB would need to be calibrated to the maximum rated output power of the amp. McIntosh's analog power meters are indeed nice.
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