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