Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Meridian 861 Bass Management issues

The sinewave generator works with the crossover on my 568.2mm. I can verify the 3dB drop in each speaker individually at 80Hz and when the sub and main speaker are both on the crossover frequency they are at the correct level or 3dB higher than the sub and main fronts individually.

I use the Stereophile CD's (Test CD2) and 1/3rd octave warble tones to get the levels correct and then use the sine sweep on the 568.2 to look for any gross peaks and valleys. Be careful though because its easy to be in a null or peak using sinewaves. You need to move around the room listening area to get a better idea if it really is a gross measurement created by the speaker. Using this method I get very good results and can adjust my sub's parametric equalizer to get a nice smooth response in my room. For the most part the warble tones are the best method to get your bass tuned in.

Ron

I'm starting to realize that if I want to use my subs separately, and not as pass throughs to the speakers, I'm going to have to hand tune them using ETF 5 as my guideline.

The processor definitely is doing something, but it is odd. I'll post the measurements that I did an hour ago. The Revel CD has you turn off the speakers when measuring the subs, and it has you turn off the subs when measuring the speakers. Unfortunately this changes the Meridian's output 100%!!! So it appears the problem is the setup method they give to get their subs tuned EQ wise. Oh well, guess I am going to have to do it the harder way.

I'll post the ETF5 measurements that lead me to this conclusion. If anyone knows why this is the case, and can explain the reason the measurements are so wild, please do so. I could definitely use the knowledge for future reference!

None of the settings were changed between measurements and the mic was not moved, only individual items were turned off, such as the subs or speakers. The items marked with "hf" are full frequency measurements, the items marked with "lf" are low frequency measurements. All measurments were done with MLS for 5 seconds.


Thanks,

- Jeff

Jeff:

What are the crossover settings in effect here? Based on the graph, it looks like the crossover is 35Hz still.

See how the "Speakers_LF" line drops down sharply shortly after 35Hz.

If one sums "Speakers_LF" and "Sub_LF" the response (output in dB SPL) looks about level based on the graph you're showing us.

Cheers,

I set them all to 80Hz, and the LFE to the setting before Full (150Hz?)

That is exactly why I am a little perplexed. They behave totally different when either the speakers or subs are turned off than when both are turned on. When both are turned on it looks as if they might be crossing over at around 80Hz (if that dip in the FR at around 80Hz on the black line is a tell tale sign of this occurring).

In any case, I have to assume it is actually working, but only when both the speakers and subs are turned on at the same time. Only because the FR isn't much higher or even peculiar when both are on at once and I do a full range MLS measurement.

It is working, but is it working correctly according to the settings I gave it? I can't tell or find out because it behaves differently when I turn part of the system off in order to measure items in isolation than it does with everything on and functioning.

Here are some separated measurements. I went and double checked my setup, and downloaded my .msl file from the 861 to the computer. Crossover is set to 80Hz and LFE to 150Hz.

Here are three overlay comparisons:

This first one is a full range MLS with bass management and without bass management (so one has the subs in "stereo mode" output and the other is without the subs in "direct mode" output).



It appears that the 861 is also equalizing their levels to match up better (I have no room correction profiles, so no room correction is involved yet!).

This second one is a separate low frequency comparison of the same two outputs.



I am not changing any of the output settings so any changes are occurring inside the 861. If the management weren't working, I suspect that we would see areas with overlapping mode reinforcement going up pretty high in SPL, but they aren't.

The third is a speakers only and the subs only comparison with bass management on. It seems that the 861 knows when there is nothing there to receive the signal. I say this because the product of both subs and speakers together with bass management turned on look completely different than it would be if you were to use amplitude addition on the signal outputs when measured separately with the speakers or the subs off like in this last pic (in the case that both were receiving the same signals). That is, if I understand how it would work correctly.

BTW, the first group of measurements got screwed up. I think something was malfunctioning in the input (as their was some strange fall off in the high frequencies due to the output being too loud). Everything checked out completely on those second round of tests though, so those are the more accurate measurements.

- Jeff

If you turn off subs the 861 automatically routes bass to the main speakers (I assume this only works with Meridian digitals).

Mark