[Boatanchors] OT: Question about audio

[Dave Brown]

PPM= Peak Program Meter.
These were introduced much more recently than the VU meter which came into 
widespread use in broadcasting circles etc around WW2. The PPM was intended 
to be an improvement on the VU meter and in many respects it is. Its 
ballistics are typically controlled by the surrounding circuitry so any old 
meter can be used (over simplification, but you get the idea) while the VU 
meter has well defined mechanical characteristics and does not rely (very 
much) on external circuitry to indicate properly.   But it depends on what 
you want, meter response wise.
I suggest you google for both types so you have enough background info 
before you make any decisions or purchase!
73
 Dave, ZL3FJ

----- Original Message ----- 
From: "W2HX" <w2hx at w2hx.com>
To: <boatanchors at mailman.qth.net>
Sent: Saturday, February 15, 2014 4:45 PM
Subject: [Boatanchors] OT: Question about audio


> Hello all,
>
> I am in the process of building a new shack. I am hoping to do more AM 
> than I used to, with more space for some nice sounding transmitters.  I 
> thought it would be sensible to have some VU meters in the shack that I 
> can route the audio to before heading to the exciters/transmitters.  The 
> idea is to make sure I am optimizing the audio levels going into the 
> exciters.  I plan to run my microphones through a pre-amp (Behringer Shark 
> DSP110) to boost the level to line level (probably targeting +4 dBu 
> balanced).  The transmitters I have will all accept "line level" audio at 
> various selectable expected input levels.
>
> The question is about VU meters. I have been looking on ebay and I've seen 
> some things I don't understand.    I have seen some VU meters that have 
> two types of meters on the same panel. One looks like the standard VU 
> meter showing -20 to 0 and then +1 +2 +3 in a red section.  The other 
> meter on the panel has the word "TONE" and "dB+Range" on it and the scale 
> is -12 to +12.
>
> Just some examples on ebay of these kinds of meters.
> 331098964167
> 231107605604
> 281193957524
>
> What is the meaning of these two types of meters? What do they mean 
> "TONE"?
>
> Question #2.  I have read about a term called "Ballistic" and the options 
> seem to be PPM or VU .  Is PPM something to do with peak vs. average? I 
> know typically in ssb I would set my wattmeter to peak and in AM or CW I 
> would set it to average. In an audio system, when would someone want to 
> look at peak vs average? (and is that what ppm/vu means?)
>
> Thanks very much for any input on this subject.
> 73 Eugene W2HX
>
>
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