VSONICS and LeQ(m) readings for Trailers

[minister]

Hi Everyone,

I had the VSONICS Meter and it purports to do dB(M) for LeQ(m) readings. I read the manual and a reading of LEQ -20 is supposed to be = 85 LeQ(m) TASA. So over 2 minutes, with the plugin in multi mode, I got a reading of exactly -20. But my TASA report came back as LEQ(m) 82.

Anyone have an idea of the discrepancy? Is VSONICS useless as an LEQ(m) meter?

I emailed the company....

[conleec]

I don't know, and I apologize for hijacking. But if you're in a bind, I can tell you that Waves WLM has a Leq(m) setting and it worked perfectly the last time I had to submit a trailer.

Chris

[Postman]

I haven't used VMeter since it was first released, but the first thing I notice is a 3 db difference between what VSonics says and the TASA report. Then I noticed you wrote "mulit-mode". Related?

[minister]

Thanks Postie,

Yes, I noticed the 3B....however...the only way to pull up the plugin in 5.1 is Multichannel Native. No option for multi-mono. But that's good! the "multi" here is not the same as multi-mono -- which I know not to use for Loudness... Then there are 3 options to pull up the plugin in LeQ(m) : mono, multi, and stereo. Mono doesn't give me a reading across all the channels, it only measures each channel but no number for the sum. Stereo, I obviously don't want. So I thought (multi). Hmmm...perhaps bad implementation on VSONICS part. I'll see what they say.

Maybe I should just get the DMM2 or WLM....

[Postman]

My poor suggestions are deleted. See next post.

[Postman]

This has been bugging me today while editing, so I re-read the Dolby 737 manual and realized that
1) I was wrong above and
2) Using sine tones, you should be able to very quickly deterimine if VMeters measures them the same as a 737. That is a basic thing it must do!

To align the 737 meter, each channel is individually to be fed a -20dbfs 1k sinetone (not 2k as I was thinking above!), and LFE is to be fed a -20dbfs 100hz sinetone. Each channel to be aligned receives sinetone while all other channel inputs are silent. The important point is that, once aligned, sinetone to Left or Center or Right or LFE will be measured by the 737 as 85 leq(m), which is equivalent to -20 on VMeters. If aligning for a 5.1 mix, sinetone into Sl or Sr will be measured by the 737 as 82 leq(m), which is equivalent to -23 on VMeters.

The manual then goes on to state that as a final check of good alignment, send the -20dbfs sinetone to all inputs (100 to LFE, simultaneously 1k to others). The meter will measure 91 leq(m), which should be equivalent to -14 (or very close, I wouldn't be surprised if there is a small factional difference) on VMeters.

I didn't realize until today how different the leq(m) measurement is from an LKFS measurement. Not only does it use a different frequency curve, which I already knew about, it includes LFE whereas LKFS/LUFS do not. Also, it responds less to the surround channels than the fronts, whereas LKFS/LUFS responds more to the surround channels than the fronts. For BS.1770 meters, a 1k -20dbfs sinetone into the 5 main inputs measures as -15.4 on an LM6. That's quite a difference from a 737. And that's just with a tone which is below the 737's "annoyance" frequency weighting.

[minister]

Thanks again Postman.

Well, something is wrong with this meter. I fed it a -20dBFS Sine at 1kHz and it read LEQ -23dB(M).

The manufacturer tells me it has to do with Room Calibration, despite the fact that we are measuring the Digital File. So they are no help.

Oh well, it was only 129 bucks. Reason I got it is because I don't do that many Theatrical Trailers. Guess I will get a demo of the WLM and the DMM2.

Tom

[Postman]

Yup, it sounds like VMeters is whack. I would verify this myself if I could. I actually have an early version on my system (authorized, not trial) but it immediately crashes Pro Tools. Probably needs updaing but there is no public download on VSonics site and frankly, it was always troublesome on my systems which is why I abandoned it. Since it doesn't work as advertised you should ask for your money back!