Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Meridian SizeCalc help needed for full range speakers

My speaker layout in the 568 will be no sub for music and logic and one sub for LFE.
My main speaker is ported with a single 11 inch woofer. It has an external amplifier. The freq. response of this speaker is down to low 20's Hz. I will be acquiring a set of stereo subwoofers which will be connected via the tape loop output of my preamp into an external active crossover. I will only be using the lowpass output of this crossover which means my main speakers will be getting the full frequency of the source. The active subs will be crossed over by the variable 4th order external crossover. So the subs will be getting their signal derived from the right and left front channels of the source playback via the 568 which is connected into this preamp which has the tape loop. If I keep the size calc value for the main speaker which is 14, then how will that effect the signal being sent to the subs which are sizecalc at 25??
If I use the 25 level for my main speakers, what real risk will occur as I am quite conservative with playback volumes with both music and movies?
How does not using the speaker protection parameters and just putting in MAX for all full ranged speakers put anything at risk?
What is happening when a speaker is designated at less than MAX with the size calc? Any low frequency roll off or limiting low frequency dynamic range to these speaker occuring with less than MAX size?
Stacy or Chris, if you have full range analogue speakers with external amps, what would you use, the MAX settings?
Thanks, mark

The size only takes affect after a certain volume level at certain freq is reached. So for your normal conservative listening level, you could in theory even set it to MAX. But then you would have to switch it back and forth depending on whether you are in cinema or music.

Also, for movies, with your setup, you are not getting the bass from the center speaker. I think even if you set your center to small, DTS will still send a full range signal to it. So you might have to sum up the LCR channels to get the full movie effect. Also, moderate listening level for HT means nothing, since there is a tendency for the studio to add something real real loud to the center channel frequently, the always want to go near that 0dBFS for no reason.

I asked Meridian for some chart or graph that correlates between size/freq/dB, but they don't have any. They said just to play freq sweep through the speakers and set the size right below the point where the speaker distorts or bottoms out (I think I might distroy my speakers in that process, cranking sweeping sine waves at such loud level for so many continuous passes.)

I have a 5.0 setup with sub for center and sub for L&R, all actively crossed over at different freq for speaker and sub. I left it at MAX for now, since DD/DTS automatically limits the max LFE to -5dBFS, but on some situations, I measure 55v peak output from the sub amp, which works out to be >750w, over the amp's 500w spec, and the output was not 100% clean. I might one day do the above freq sweep/size adjustment if I don't mind taking the chance of blowing up the sub and/or amp.

actually about my center channel it does have a full range freq response as it has an 11 inch woofer in a transmission line enclosure. All my speakers are designated Large Analogue.

Buehler, anybody, Buehler?

Looks like everybody is at CES, so it is pretty lonely here.

That chart is totally inaccurate, since it is just a general guideline. I have a sub inline with my main speaker, and from the speaker size setting, I should set my speaker to 11 (12" vented sub shared by 2 speakers, so it would be 2 x 12" + port = (20 + 2)/2 = 11 ?) Why would I want to set my mains to speaker size 11 when the sub itself could produce over 115dB?

Just follow what Meridian said, test with freq sweep build into the processor and set it to one size below where the driver bottoms out.

If you got all the time in the world, you could do a freq sweep with different speaker size/dB settings. You don't have to use your ratshack meter and risk blowing up your speaker/amp. Just take the voltage reading out of the preamp or power amp w/o any speaker attached.

I do not like this feature. Size calculation is innacurate. I recommend setting it to maximum always. I assume max is the same as OFF. We have used common sense for years... I do not like the idea of 'limiters', period, digital domain or not, a limiter is a limiter. Just set to max and forget about this absolutely cheesy size calculator.