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  #1  
Old 05-19-2016, 01:16 PM
jjsoundoc jjsoundoc is offline
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Default LM-100 "off" by 2 units

Using 1770-3 specs and finding that the LM-100 reads consistently 2 units
low when compared with a TC LM2, and Izotope Insight.
I have a screen with the LM-100 remote software at the side of my console so I can check level while mixing. Unnerving to find I can't trust it.
Anyone else encounter this, or have an idea of what's happening?

Thanks,

JJ
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Old 05-19-2016, 05:12 PM
Postman Postman is offline
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Default Re: LM-100 "off" by 2 units

LM100 doesn't do 1770-3 because it does not employ a gate as spec'd by 1770-3. What is happening is that the LM100 is always measuring and applying to the long-term average, even in silence or very quiet areas. 1770-3 compliant meters will ignore the low level stuff (a threshold which is moving and determined by surround material and previous measurements). Since low level sections will not bring the long term average down, 1770-3 meters typically measure 1-2 db louder than earlier LKFS (BS1770) meters.

Dialog detection built into LM100 is a type of gate, but not the same principle and using it may bring the reading closer to 1770-3 but not going to be the same.

It is pretty handy for short-term measurements while mixing, though.
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Old 05-20-2016, 07:06 AM
Postman Postman is offline
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Default Re: LM-100 "off" by 2 units

One more thought on this,

LM100 can measure with leq(a) or with BS-1770. leq(a) is outdated, use only lkfs! leq(a) will often be different that BS-1770 because it uses a different weighting curve and is frequency-sensitive in a different way than is BS-1770.
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Old 05-20-2016, 07:33 AM
jjsoundoc jjsoundoc is offline
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Default Re: LM-100 "off" by 2 units

Thanks for your help Postman.
I'm using 1.4.2.0 software on the LM-100 along with remote software on a PC. I'm able to select ITU-R BS. 1770-3.
It seems to be gated; when there's no sound, the reading "freezes" as you'd expect.
Are you suggesting that even though 1770-3 is a measurement you can select, it isn't "true" 1770-3?

jj
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Old 05-20-2016, 09:13 AM
Postman Postman is offline
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Default Re: LM-100 "off" by 2 units

I wasn't aware that LM100 had an update for 1770-3! I inquired some time ago and had understood that software was not updated past what I had installed, which did not have gating. I don't recall its version number.

If yours does actual 1770-3 then I don't know why readings would be different. On my unit, which I sold a couple of weeks ago, I checked its LKFS reading against a different meter using a 50 minute stereo mix that had practically no quiet moments. The readings were the same as far as I could tell. Since LM100 rounds its LKFS display up or down to the nearest unit, 10th of a DB differences are not obvious.

edit: The most recent software I can find on Dolby's site is "LM100 Upgrade Package V1.2.4.2", and I am fairly certain that is the version I was using. How did you get a later version?
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Old 05-20-2016, 10:26 AM
Postman Postman is offline
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Default Re: LM-100 "off" by 2 units

Further research reveals links to the remote software for LM100 V1.4.0.8. Boy, if I known they were still writing software updates I wouldn't have sold my LM100 for $55! I guess you have to know the right people at Dolby.
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Old 05-20-2016, 10:46 AM
jjsoundoc jjsoundoc is offline
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Default Re: LM-100 "off" by 2 units

The problem was the LM-100 itself, found another one, installed it, all is fine.
Still can't figure out why it was 2 units low.
I'll make some space above and below the box, could be overheating.
Still need to figure out what to use when the LM-100's start failing.
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Old 05-20-2016, 11:37 AM
Postman Postman is offline
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Default Re: LM-100 "off" by 2 units

Unless analog input which has input level control, it doesn't make sense. Did you try listening from the headphone jack?
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