Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Cinema / Discrete / 10dB - definitive answers required!

A link to AVIA Pro's audio test disc manual which contains discussion of DD/DTS mastering. I use this disc to great effect to set up my Meridian system.

http://www.ovationmultimedia.com/files/2e-AviaProAudioManual.pdf

Mark

Normal policy would be to redistribute the LFE channel amongst all the full range speakers.

Of interest here is how Bass is summed both electrically and acoustically. 5 full range channels will combine common low frequencies at a power summation. This means that 2 channels will combine by 3 dB; 4 channels by 6 dB and 5 channels by 6.989 dB. When common bass frequencies are derived and summed to a subwoofer, the summation is electrical and thus two channels sum by 6 dB, 4 channels by 12 dB and 5 channels by 13.979 dB.

I suspect this might be part of what some of you are hearing between modes, even though Meridian take great care to ensure that in many of their modes this is somewhat compensated for.

I'm pretty certain that only thing the CINEMA DSP mode does is add the +10dB to LFE...

But excellent question regarding what the processor will see the incoming PCM as... perhaps the config software will allow us to override the usual restricitions...

Mark

Are you sure?

Scenario: A G98AH decodes a DD5.1 movie soundtrack.

Q. Does it add the 10dB to the LFE channel?
A. It must because there is no guarantee it will be used with a Meridian processor.

Q. Does the G98AH decode differently to a G98DH?
A. I think this is unlikely.

Q. If the G98DH adds +10dB to LFE on decoding, does Cinema also add +10dB?
A. Of course not. That would be wrong.

Q. Do all multi-channel analogue DVD players put out LFE which is deficient by 10dB?
A. I don't think so.

Q. If a G98DH puts out multi-channel MHR, it knows that it is connected to a Meridian processor. In this case, does it decide not add the 10dB, and the MHR metadata (Movie6) signals to the processor that the "Cinema" DSP should add the 10dB instead?
A. I think this is unlikely. It's just too complicated.

IMO, all DVD(A) players should put out the LFE channel at the correct level, based on a flag in the DD soundtrack. Taking this further, the decoder part of the G68/861 should do the same.

But here's the kicker: Listening to a DVDA today (via m/channel analogue), there does appear to be a difference between "Discrete" and "Cinema". Not quite sure what.

Edit: Unless it is standard practice for players to put out LFE at -10dB and for processors to add 10dB, but this feels wrong to me.

Edit2: My intuition tells me that "Discrete" must do nothing to the sub channel, because the processor has no idea of the origin of the analogue signal. Why this is displayed at -10dB, I'm not sure.

Yes. It's normally the processor's responsibility to add the +10dB. If this is also added by the player then it needs to be defeated somehow OR you tell your processor to use MUSIC mode instead to avoid a double +10dB boost.

Mark

So if a player outputs a decoded movie, I should assume it is 10dB deficient in the sub channel?

But if it is outputting music (DVDA, SACD), I should assume that the sub level is correct?

(Thinking aloud) So if we apply "Discrete" to a m/channel analogue DVDA input and the LFE level says -10dB (the default), what does this -10dB mean?

Actually - I'm now confused

Manual says CINEMA does nothing to the signal. If you want to REMOVE 10dB you would choose DISCRETE.

I always thought CINEMA added 10dB but guess I'm wrong *sigh*

Mark

Surely people can hear whether there is a 10dB discrepancy? Its not like its an insignificant amount.

Don't ask me though, I don't have golden ears and can't hear the subtle nuances that many people talk about. I just know what sounds right and what sounds wrong to my ears and I'm quite happy to entrust the technical correctness to Mother, even though on a couple of occasions, the odd audible gremlin makes its way to the speakers.

Who would be best to talk to at Meridian? Des would know, but I haven't been able to get hold of him for five months...

Wish I'd thought of this question for Bob at CEDIA!

Well, you do need a reasonable amount of LFE to start with. I'm sure the usual DVD calibration discs have LFE test tones; I'll try one this weekend, measure it with a meter, and report back.

You can read up on -10/+10 (and 15) here:

http://www.avsforum.com/avs-vb/showthread.php?p=8855640#post8855640

Ok. I used my PAL Digital Video Essentials DVD (Chapter 8/11 - Band Limited Pink Noise - LFE).

I set my volume and meter (C/slow) so that (1) below read -10dB.

1) Bitstream decoded in G68 - Discrete: -10dB (G68 LFE display = -10)
2) Bitstream decoded in G68 - Cinema: 0dB (G68 LFE display = +0)
3) Soundtrack decoded in Oppo 980 - Discrete: -10dB (G68 LFE display = -10)

and, wait for it...

4) Soundtrack decoded in Oppo 980 - Cinema: -5dB (G68 LFE display = +0)

So there you have it. Cinema definitely applies a boost vs. discrete. And the result (4) which I double-checked suggests there is a bug somewhere...

For completeness, the test system was 5x DSP33 with *no* sub. In both Music and Movie bass management screens, all five 33s were set to large.