Does using dual woofers but only one for mid’s improve mid driver integration?

[sebackman]

Dear all,

In somedesigns JBL is using dual woofers, as in the E2 & 4435 (high end) and JRX125(bottom end J) and probably several others in-betweenthe booth ends of the spectrum mentioned. In those designs they are only usingone of the woofers up to meet with the mid-range driver.

Does thatreduce the interference between the different drivers when crossing over to ahorn and driver?

Some important JBLspeakers like the DMS1 (and many more) uses both woofers all the way up to thedriver (if I recall correctly).

Is the reasonthat the helper woofer is crossed at a lower level in the newer designs only drivenby sensitivity in the lower end or does it actually smoothen the transitioninto the driver/horn with only a single woofer?

I do understandthe value of having two woofers in the low end but this is really a question ifthere is significant value of only bringing one woofer up to the low/midcrossover point.

Using an activecrossovers can of course produce very steep slopes reducing any interferencebetween the drivers, but potentially at the cost of sound quality and experiencedfrequency “holes” in the sound stage.

How is thistreated in SAM1-LF and the other dual woofer speakers like S3900/S5800/880Array

Thoughts?Experiences? White papers? Measurements?

All the best
//RoB

[fpitas]

In a 2.5 way like the D66000, I'm pretty sure the "bass only" woofer is rolled off appropriately to serve as baffle step compensation (LP 6dB/octave @ 150Hz). As for using two woofers up to crossover, it's (among other concerns) a matter of polar pattern, and the necessity of matching polar patterns between the midbass and the horn at the crossover point.

http://www.jblsynthesis.com/download....wt.pap.vF.pdf

[4313B]

How is thistreated in SAM1-LF

SAM2LF - two eights are used in parallel in an MMT configuration to keep the baffle width narrow while increasing output.

S3900

two tens are used in parallel in an MMT configuration to keep the baffle width narrow while increasing output above what a single twelve could accomplish. The S3900 design is an attractive design for a large number of people. Narrow baffle with significant performance potential.

S5800

two twelves are used in parallel in an MTM configuration.

880Array

two eights are used in parallel in an MTM configuration.