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Ian,
Read the Following.
Perhaps you've skipped quite a few posts SUBSEQUENT to the one (#11) you refer to in post # 60...
Post # 26: "So, if don't want any regret after, I will built a 120L box (a la M9500), and if necessary use the room and a bit of Eq."
Post # 39: "At first, I would rather built directly the "final" enclosure... with the good volume. It's already a lot of work and money..." "About the size, ... what I only need is the best balance betwen volume and performance."
Post # 46: "My idea was to fit the 1400Nd on the En5 instead of the 2234H in order to have an idea of the low frequency. I don't want to modify the box!
Someone knows the volume of the S7500?" According to JBL's "Low-frequency enclosures" document I have the EN 5 is a 5 cu. ft (140 L.) enclosure. And the answer to the question was given as 4.1 cu. ft. (post # 47 and others).
Post # 54: "I added 252G in the win isd similation." (Didier)
Available time and money are issues Didier mentioned previously. The 1400 nd he has on-hand with the recone kits, whereas the 252G he doesn't as far as I know. Moreover, he added the 252G to his list of options and he's already modeling it for himself in Win ISD so there's no need for me to do that for him...
I've already given him numerous proposals to use competently what he has on-hand, thereby saving time and money...
Richard
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RE Post # 59: "We don’t know how you propose to place the enclosures but the below extract of the manual is a guideline."
The speaker placement directions given for the S 7500 are quite different than those given for the M 9500 Didier wanted to build. One has to compare comparably designed stuff. One designed for closer to boundary placement and the other designed for farther away...
Plus, this is not really new under the sun, Roy Allison (Allison Acoustics) built his Loudspeaker business in the seventies on that closer to boundary placement (The Influence of Room Boundaries on Loudspeaker Power Output, JAES, V. 22, N. 5, June 1974). Eargle provides, in his Loudspeaker Hanbook, 1997, p. 292... , a nice summary and explanations of Allison's work.
As for "... the low frequency cut-off is very low..." no number is mentioned in the extract, nor + or - db of effective response. I mention that because some fellows thought the M 9500 VLF response would be great but as I mentioned in post # 58 its not really enough to be "thrown to the floor". So pending some real numbers for S 7500, which remain to be seen, I'd rather proceed with caution before opening the champagne, as they say.
Richard
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I am away from internet access most of the time during holidays so obviously l am not up with it.
But, Perhaps it the time difference but Didier did only post yesterday on the 252G hence my comments
Unless you are a mind reader of course.
At any rate, to keep you entertained I think it would be a reliable thing if you posted a simulation of dual 252G design like the S5500
How do you know if Didier has simulated it correctly?
What’s happening here is still bundle of thoughts.
At a later date anyone viewing this thread might see the 252G an option given the 1400n is virtually in obtainable
I think the 252G is still obtainable as a spare.
Also do you have any capacity / bandwidth to model the network and systems integration with real driver data?
I assume you would have given your knowledge and references.
If you don’t then it’s worth looking into.
I use LEAP 5, LMS and Soundeasy.
The wider picture of exactly what JBL do to make a system like this work is nearly always not obvious.
Passive network voltage drives and proximity of other drivers often implicate not just the horn equalisation but the woofer in situ. The active network voltage drives are not necessarily the same.
The overall published sensitivities of both systems and the 1400n data sheet and driver response are a starting point.
If anyone has measured data from Clio or LMS or similar of the 1400nd you can get very close to JBL.
Didier fortunately has a digital crossover so with some trial and error he should be able to get a good result.
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No time for beating around the bush...
