Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Mconfig : explanation about subwoofer size parameter ?

Hello,

In my system (G68), the 5 speakers (Yamaha DSR112/ERiS E8) are set as 'small'.
My subwoofer is a JBL 4645C (18") pushed by a Crest Audio 8001.

Last time I launched Mconfig, I have seen a column 'Size' with a value set to 0 at the end of the subwoofer line in the calibration page.

The range of value is 0 to 30 (and Max after that).

Set to 0 or 30, i have heard no difference when playing a CD in 2.1.

But yesterday, watching Dunkerque movie with my wife, my subwoofer was producing great big clean basses with a lot of punch (no boomy result).

The size parameter was set to Max.

So, how does the parameter work, what does it do?

I have found only one post on the forum about this with no more explanation

Serge.

In the 861 Documentation

I used to set sub size and other config via the front panel of my G61. When I got to the subwoofer size I gradually increased the sub test tone (not to be confused with the test tone used for balancing the sound level along with the other speakers - it's a separate sub size test tone) from 0 to max and listened for any distortion as the level went up.

The idea was to get to the point of obvious distortion, then back it down a little for safety. My analogue sub handled max with no problem, others may not. Obviously, having it set lower than necessary can result in losing some bass at times, when you don't need to.

With a competent subwoofer you want the size set to MAX. Then you get the complete full signal.

0 does not mean function defeated, it means the signal is being edited and subwoofer "protected".

Ok but what is the difference between the "edited" signal and the full signal ?
It's a compression of the peak levels ?
Meridian does not document this functionnality.

From the way it sounds as you slowly increase the setting, it sounds like a roll off filter getting less and less until max where there is no filter being applied. If I get time one day, I'll graph it.

This graph will be very interesting !

What configuration (hardware/software) do you use to do this kind of measures ?

The manual for the 601 DSP Pre-Amp includes 19 frequency response graphs for the different DSP programs in the 601. (The 601 was the 1991 precursor for all of Meridian's later DSP processors).

Have a look at the speaker equalisation curves for bass control on page 58 and wall control on page 59, this may be what you are hearing:

Meridian 601 User Manual

Interestingly, I have not seen these graphs repeated anywhere else in Meridian's documentation. I suspect two of them, which are based on Bob Stuart's psychoacoustic research, are the heart of Meridian's unique clear sound. See the correction for human hearing equal loudness levels on page 62.

The EQ curves for DSP speakers are slightly different. They did make it into the early DSP manuals (e.g., the appendices, p.61, of this 5K user manual).

I doubt they relate to what you’re hearing with the sub level on a processor though, I suspect that’s more dynamic compression than EQ.

Thanks for the pointer to the 5K graphs; I'd not spotted those before.