GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Problems with horns: upper bass

Post Subject: On Projected Mouth SizePosted by Dresden on: 11/17/2008

Mouth size is the one dimension I've struggled with most.

As of the present time, I've deduced to use a mouth size that may prevent me from achieving the target frequency of 40Hz, and instead produce a frequency of about 55Hz or even 60Hz. I cannot know the exact cut-off until the horn is built and tested.

It's interesting to see that jessie.dazzle came up with 2.90 meters for the 40Hz cut-off (the design implemented using an 8" throat), because that's the same figure I arrived at in an approximation using the same throat size. Thus, previously reaching the conclusion of having to build at least two prototypes (one which includes a bend in the horn prior to the 90 degree bend exiting the mouth), may ultimately provide accurate, unfettered reproduction to 40Hz. Nevertheless, a bend in the horn (aside from the one required at the mouth exit) is something I don't intend to use in my final design. (Alas, if only I had 12' ceilings.)

The 'real-world' target design will have a height of 7'6". One design alternative which appears more likely to become a vital part of the final design is the use of a second 2206H driver to load the rear horn in leiu of simply using the rear acoustic energy of a single 2206H (the design has a 7" throat at both the front of the driver and the rear of the driver of a common chamber). For obvious reasons (increased cost), I'll initially try to forgo the need for the additional driver, implementing the dual-driver chamber configuration should the performance (or lack thereof) of Mid/Upper bass frequencies warrant it.

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