Meanwhile... I have not dealt with high Q drivers. However, have designed several very successful automotive mufflers for my Mustang 4.6 V8, VW VR6 and Audi 1.8t. The Audi had larger expansion chamber and I dealt with its’s self-resonance with such a resonator.
The Mustang has a pair of rear mufflers tuned with 129 Hz resonators coupled to the transfer/expansion chamber.
With the VR6 I went all in with three separate resonators (allot of room for muffler), 90, 140 and 250 Hz. The effect is decoupling of the source from the termination/mouth and acoustically softer/larger muffler. Both are favorable for flow. Added feature is the fact that exhaust is quieter at all frequencies except around tuning frequency at big load when it is excited and adds a pleasant note.
And to bring the fruit of all that back to DIY audio, I learned that with vented enclosures the situation is different, source/excitator, volume of the chamber, mass of the port and the Helmholtz resonator. While digging around classic transmission lines, I started around Radford S90 and continued with newer art. Some TLs have such resonators coupled at the beginning of the port or in the port itself.
My initial quest was for virtual enlargement of the enclosure volume without going in the erroneous path of EBS or the speculative path of aperiodic or variovent.
Should simulate a vented version sometime soon.
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The highest efficiency of the Helmholtz absorber is at the end of the length resonance where the standing wave got its pressure maximum. So, for a horn or TML it's sometimes quite difficult to include it in the construction because of its physical size and a non-optimal placement reduces its effectiveness, which means, it probably will matter - in praxis.
ICG
Can it not be placed close to the source of the pressure too? Like right next to the woofer?
In praxis they may not be as effiecient in sometype of enclosures, as in other types.
And nobody says it is easy to fold a TL or a horn, adding a helmholtz resonator at the right spot makes it just a bigger challange.
Can it not be placed close to the source of the pressure too? Like right next to the woofer?
In praxis they may not be as effiecient in sometype of enclosures, as in other types.
And nobody says it is easy to fold a TL or a horn, adding a helmholtz resonator at the right spot makes it just a bigger challange.
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You can place them in various places but they are most effective at the maximum pressure knots. In a horn it's often very difficult to include them in the construction because of the horn shape. In a BR or sealed enclosure you can implement them often even after the fact, that's often impossible at a TML or horn.
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