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

That seems just plain wrong.
Great work George.

With a G61 and pair of 5200's and analogue rears there seems to be a noticeable improvement, the DSP's sound fuller to my ears. Need to do a proper comparison, but all good so far.

Thanks for the tip.

I'll try a full sweep next rather than just one frequency, it may explain some things.

I tried to record all of Avatar (Only recorded Front Channels with +3dB on all channels, no LFE configured, all set large from G68 out). My laptop went to sleep about 1.75 hrs in.

It looked pretty darn good. It did clip mildly about 1/2 a dozen times in the low frequencies. Maybe 100 samples out of ~300,000,000 samples. A little clipping is fine (you might even say it's a good sign to clip a little because if it doesn't clip just a little it means your not pushing it to the max dynamic range).

I did record the THX logo. It clipped more significantly. Then I turned LFE on and looked at the data "unclipped" and the orginal audio has modest clipping built in (lots of flat top peaks below full scale). It is not nearly as tidy as the movie itself. Basically it has a lot of flat top peaks that are not at full scale (it was clipped in prior mixing). That logo has probably been transferred a few times. It sounds fine with or without LFE configured though.

I mentioned I could not record from HD621. I can. It was the EMU refusing to record at 48Khz. The TASCAM records anything with encryption off. All I do is set non 24/96 speakers and plug TASCAM into the output of the DSP speaker and I'm ready to record.

Perhaps try pink or white noise in the LFE channel with nothing else in the other channels? It would be very interesting to see the frequency profile of the 5.0 channels after Meridian gets hold of them!

Left as an exercise to the fellow with the new TASCAM

Here is a screen shot of the Recording of the Front 2 Channels.

+3dB on all channels.
With LFE Driven 60Hz Full Scale.
All Large vs Rears set Small and Crossover at 150hz.

By the way there is 7.6dB of headroom. If anyone can figure out how that is arrived at I'd love to know.

In theory the signal should be Full Scale +10dB (split among all the large channels).

Great work as usual George- thank you. Could the extra headroom be from dialogue normalization?

This is all low frequency stuff we are currently discussing. So that does not account for the 7.6dB head room in LFE data.

But dialog normalization could be just as applicable as the EQ stuff was in Trifield on the center. So yeah I guess it could.

Even if headroom was needed for the center there is no need to add the headroom to all channels. You can add the headroom on the channels that are needed then boost them later in analog to get the correct level.

George,

Your getting some weird readings! Were you using TRueHD or DD?

See this link: http://www.hometheaterhifi.com/tech...hannel-in-51-digital-surround-sound.html

Seems usually the LFE will go to the front speakers for DD but in the case of mixing in PCM Meridian is doing something different. Note down mix to 2.0 throws away the LFE. Whats really interesting is DTS! Rear channel bass is your LFE. I never knew that.

I have no idea how TrueHD decoding is handled if you select no LFE but like I said mixing it in PCM like you do with our setups Meridian could be doing something different.

I always remember LFE going to the fronts not all speakers for DD.

The Test discs usually set LFE level with the main channels to balance all the channels to one level. I never found one that played LFE 10db high. I had to make my own to do that.

I guess every manufacturer handles it differently.

Ron

Ron, no codecs are involved here, a BD/DVD "Player" is not involved either.

I'm feeding HD621 (2 Channels of LPCM) of Test tones I generated in Audacity from transporter.

I moved the "Main L/R Channels" to the Center/LFE on the G68 so the G68 thinks it sees 5.1 (LPCM) with Center and LFE being driven (60hz Full Scale). All speakers set large. With LFE configured nothing came out rears or sides (as expected). With LFE not configured it sent LFE to all large channels.

Also as far as G68 is concerned (even if I did use a spinner) I would expect SACD,DD,DTS,DTS-MA,TRUE-HD to all me handled the same from HD621. They are all 5.1 LPCM because the PS3 is set to decode code them all and has no bass management.

Ron, I will rerun my tests this weekend but the last time I tried this with the VE DVD, the LFE track played through all my speakers which are set to large.