Fra saksa til oversettelse:
First measurements done. The sound is superb and there is no cabinet sound.
However, we discovered soon by ear and confirmed by measurementsthe following deviations due to some acoustic
variables that can not be foreseen by calculations only:
1) Tweeter is very close narrow to woofers: This arreangement have many advantages, but on the opposite side the woofers surface acts like a un-even baffle vibrating surface.Result is a minor overlay/peak at 1000 hz, not a big deal to straighten out by adjustments in the crossover.
2.1) There is single port only which is vertically rectangular and located close to one woofer:
A naked woofer will not play bass (without EQ). A tiny open baffel do not help much, a
really big baffle and you have a perfect OB. Well, not unknow stuff at all...
Here the port will partly act like a hole in a baffle and the pressure partly evacuates (not to be mixed up with wave lengths) from the rear of the woofer thru the port, causing a short circuit.
2.2) The inner cabinet is merely shaped as a duct (not a box) with the port acting like a branch.
The pressure build ups and point of pressure maximums at the different frequencies
was not calculated (a kind of MLTL effect?)
This caused the bass roll of to be approx 10hz higher than calculated.Searching for more information
regarding MTM and bass reflex in small cabinets, it would appear that the port should be placed between the woofers (Like Seas Odin & Frøy, Martin J. Kings MTM-Satori, Wilson Cub and so on.) Or: Two ports of course as Madisound did advice.
The solution here is to set up an internal divider to create approximately the same distance to the port and allow for equal pressure build up.(Why the the heck did I not have a mock-up cabinet)?
Well this is not big issues to straighten out, just want to share the experiences.
More to come after finishing the project.
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Ovenstående brysomheter ble løst i går da vi hadde arbeidsstue i Løten
Rød kurve er etter justeringen.
Bump ved ca 140 hz skyldes at vi fjernet dempemateriale i bunn for tilgang til filter (søyleresonansen).
Små ujevnhetene ved impedanspuklene skyldes forstyrrelser undertegnedes tramping under målingene...
Filteret er nå tilsatt LCR i bassen, LR i diskanten og seriemotstand ble øket fra 1R5 til 2R7. Legger ut nytt filter senere hvis interesse.
Og dette bildet har tippet over: