Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems LFE on Mono Sub Setting

My preferred type setting on my 568.1 is "All Small Speakers and Mono Sub" with a Xover of 80Hz on Music, Logic and 5.1. I find this gives the fullest, cleanest and most consistent bass in my room.

On some DVD's I noticed that the really low end stuff seemed to be missing, so I decided to run the sine wave tests and measure with my SPL meter. I have discovered that bass output is fine until you reach 30 Hz, where the output completely dies (like a brick wall filter). Using a CD with tones gives the same results.

When I change the type setting to either LFE or Centre Sub, the problem goes away, and I can measure good bass output levels down to 15 Hz, whereupon my sub then decays. The only problem is that these type settings do not give as flat and high quality bass as the Mono setting.

Des Ford at Meridian is trying to help me and running tests. At the moment it looks like a software issue, which suggests that others may be experiencing the same problem.

Is anyone else using a type setting with Mono sub on 5.1? Have you found a similar problem? Anyone else taken measurements?

Cheers,
Steve

Hi Steve. I use the mono setting and have also been speaking to Des about sub problems. He asked that I send him the MSF settings for my 568.2mm which i duly did. I had set my sub to mono/mono/LFE (60/65/80)(large/large/large sides&rears) on the suggestion of my dealer and found the bass wholly lacking on DVDs. Restoring it to mono brought the bass back.

According to Des, the mono option delivers almost twice the db of bass that LFE offers -rather than "better quality bass." The bass was just inaudible with the gain level of my sub.
Given your experience, I am going to try the following : Revert back to LFE for 5.1 sub but significantly increase the gain on the sub itself. Then, in the settings, turn down the sub output for two channel sound, to ensure it doesn`t overwhelm.
Try messing about with the sizes of your speakers. I actually have a small centre and rears but find the sound is better with them set at "large."

Hi Pat,

Thanks for the quick response. Interesting to hear you also have problems. From talking to Des and from my own experimentation, the bass is only "doubled" if you select Mono and set speakers to Large. This does not occur if you set speakers to Small.

I've now tried just about every combination, including Large Mono, Large LFE and Large Centre Sub. On each setting, I recalibrate levels, so that my testing is consistent. On any setting with Large, I get bass boom in my room (from Dynaudio speakers), especially with music (both CD and concert DVD's). With Small Mono, I get greater bass clarity because the boom is virtually removed (I guess because of room modes) and bass output does seem flatter (peaks at 35 Hz and 70 Hz are reduced significantly).

My problem is that everything is good with a Small Mono setting, except that there is no measurable LFE signal below 30Hz going to the Sub.

Pat,
You wrote:

If you have the speakers all set to large, Mono does nothing i think. So only with a 5.1 movie source you would have output from the woofer since that is set at LFE.
So that you have more output with the setting mono compared to LFE does not sound strange to me. If you have that with DVD's the bass information under the crossover freuqency is also sent to the woofer. In setting LFE, only the LFE track information is sent there.


Steve,
Was your impression that the Sine Wave generator has a problem ? Or a problem in the software for bass management in the Meridian.
I think some (test)DVD are also wrong with their LFE levels.

I have all speakers set to small, crossover around 70 Hz and mono/mono/mono
Tonight i will try to test this as well. I think either Avia or DVD platinum has the right info in the LFE track.

Jaco

Jaco,

My findings on sub-30Hz LFE with the Small Mono setting was based on 1) the 568 sine generator, 2) running a CD of Frequency Tones in Stereo mode, and 3) listening to various DVD's with known sub-30Hz content, e.g. ATOC, Toy Story 2, Titan AE, JP3, etc. On the movies listed in 3), there is a very noticeable difference in deep bass between the Mono setting and a LFE setting.

Steve


[This message has been edited by stevec (edited 02-03-2004).]

a workaround if you have analog speakers is to set the mains as large, designate no sub and then run the main interconnects through the sub and the highpass back to your amp.

Jerry,

I tried this once, but found it only made the room peaks worse and the sub was virtually impossible to integrate in my room.

Steve

I recently got my DSP5500s back from their 96/24 upgrade and was re-running my calibration. I have the DSP5500s and my DSP5000C set as Large DSP 96/24, my side and rear Gallo Micros set as Small Analog, and my D1500 set as Mono in all modes. Crossover is set at Meridian default (80Hz) in all modes as well. In addition, the DSP5500s and DSP5000C are set for Corner in their own settings.

I thought that since the L/R/C DSPs are all set as Large they would handle their own bass, and only the bass from the Small Analog sides and rears would be directed to the D1500.

That is what happens in Direct mode, but in Stereo mode, bass is being directed to the sub as well as coming from the L/R speakers, creating too much bass. Presumably bass from the L/C/R is being directed to (and supplemented by) the sub in all the other modes as well.

I don't think this is what is supposed to be happening.

Comments?

[This message has been edited by Frank (edited 02-03-2004).]