Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems +3dB "LevelPerfect" Tweak Performance Improvement Poll

Sorry George, do ask you again.

Iam confused now.

Look at your Trifield EQ curves,
all EQ have a +3dB boost from 20 to 200Hz,
then Q2 and Q3 further boost at higher frequencies about +3dB more,
means up to total +6dB compared to the L/R (when they are full scale).
In Trifield the R/L are only on high frequencies (above 8kHz) at the same level as with direct mode.

So when you boost all three speakers(all 0 db calibrated) with your +3dB,
you shift all front DSP to real full scale (on M terms +3dB).
As (from the EQ curves) the EQ are minimum 3dB higher all EQ INCLUDE flat EQ can get saturated with +3dB(when the recording is full range).
And EQ2 and EQ3 get even higher up to +6dB above full scale.

So why you then writing on your gain optimizer tool

---- Trifield DSP Preset Centre level Center EQ NOT FLAT adds 3.0dB yields 6,0dB (Clip risk 3,0dB)--

only clip risk 3,0 dB, its a 6,0dB risk.
Only for EQ flat and maybe EQ1(as is just a touch greater-0,5dB ?- as EQ flat) this 3,0 dB risk is correct.
For EQ1 and EQ2 the risk is here + 6,0 dB.

You wrote

"I later confirmed DIGITALLY that EQ3 does indeed need exactly 3dB headroom and Flat does not need any headroom. So +3dB and Flat is safe. And +3dB and EQ3,EQ2,EQ1 is not safe."

So thats fit not to the EQ curves.

Or when the curves measured digitally -as you wrote the curves are measured analog-
are the shifts are different?
When your statement in your programm is correct,
then all the EQ curves below 200 Hz are NOT shifted compared to the mains.
So only in frequencies higher the 200 Hz are the +3dB shift?

When that is true, it explain your writing.

So actual who much the EQ are shifted digitally ?


Another point to make the not full scale from M better:

There are level differences or offsets in the DSP presets.
This are coming from the listening tests and experience of M.
So I mean, these level differences should be left the same when the gain of the DSP are shifted.
If not, its sound different as M "designed" the sound.

So a solution could be

1) to setup each speaker to +3,0dB(M) means the scale of M.
In reality its real full scale or 0dB.
So we have the best resolution and have no lost here.

2)Then start the standard speaker calibration so every speaker is calibrated to the same SPL.
So you get for every speaker a different minus number.
Then you know how much offset is necassary to get the same SPL for each speaker.


3) For EACH DSP preset, there is a maximum signal level.
for example EQ3 have a level 6dB above L/R and maybe 26dB above rears.

4)Now the prozessor take care in EVERY preset,
that the maximum level doesnt go above 0dB(real dB).
In Trifield this is the center speaker, the prozessor knows how much every speakerlevel have to shifted from maximum.

5)Further the prozessor know, how much the speakerlevels have to be shifted to get the same SPL.

6)Then the prozessor calculate for the selected DSP preset, how much each speakerlevel have to be shifted.

7)Knowing all that, the prozessor adjust the VOLUME(not make the dB shift as now in calibrate) for each speaker to get the correct necassary SPL level.

8)What the difference to the regular procedure?

EACH speaker is then on full range(highest resolution) and produce the correct SPL with the volume adjustment- means the hybrid volume regulation from the DSP- and that mean not to loose resolution.

This procedure only sounds maybe complex when you first read it,but its simple.

And as M can set each volume in every speaker with a change in the communication sw,
it shouldnt be a big deal for them.

What do you mean?


Robert