Reading this recent article and Bose patent (not patented actually), I would like to ask if these resistors can be applied to FR cabinets to dampen resonances:
https://audioxpress.com/article/pat...ive-elements-for-ported-transducer-enclosure/
Thanks,
Roberto
https://audioxpress.com/article/pat...ive-elements-for-ported-transducer-enclosure/
Thanks,
Roberto
Poking around, I got to this which does appear to be a US patent:
https://patents.google.com/patent/US9913024B2/en
The 'resistors' are the usual sound-absorbing batting or material commonly used in loudspeakers. And yes, they appear to 'fix' resonances from the cabinet's internal dimensions and should work as well in a FR cabinet.
How did they get a patent for that?
They paid a patent attorney to write it up in patent legalese and send in the patent application form, which is pretty much all you need to do (plus wait around a few years) to get a patent in the USA. I've seen this for at least the last quarter century.
https://patents.google.com/patent/US9913024B2/en
The 'resistors' are the usual sound-absorbing batting or material commonly used in loudspeakers. And yes, they appear to 'fix' resonances from the cabinet's internal dimensions and should work as well in a FR cabinet.
How did they get a patent for that?
They paid a patent attorney to write it up in patent legalese and send in the patent application form, which is pretty much all you need to do (plus wait around a few years) to get a patent in the USA. I've seen this for at least the last quarter century.
You can use them anywhere you like if you want to introduce some resistive / restrictive pressure bleed.
Bose sometimes come up with interesting ideas (and this is too), but it's just a variation on something that's been occasionally used in audio, and especially induction / exhaust design for years.
Bose sometimes come up with interesting ideas (and this is too), but it's just a variation on something that's been occasionally used in audio, and especially induction / exhaust design for years.
@6thplanet can I ask you to elaborate more?
I'm curious on how they have done it so to understand if it can be applied in other systems as well.
I'm curious on how they have done it so to understand if it can be applied in other systems as well.
The patent explaines the concept. They basically use a long port to achieve a low tuning, then the restrictive vents cure issues with the port. This in conjunction with DSP helps their products produce adequate bass from small drivers. With the passive radiators, they can tailor them to give a nice low end and tame things with DSP.
Having active control allows a lot of leeway to sculpt to frequency response. Bose utilizes this pretty well. There are a few things I've mentioned to them to improve things a bit, but has fallen on def ears. I'm just their repair tech, not an engineer....what do I know.
Having active control allows a lot of leeway to sculpt to frequency response. Bose utilizes this pretty well. There are a few things I've mentioned to them to improve things a bit, but has fallen on def ears. I'm just their repair tech, not an engineer....what do I know.
I’m sorry to ask something that might be obvious for you, but the idea is to design the vent so that where there’s a pressure peak on one side, there’s a low pressure point on the other side, then “leak” a controlled amount of pressure to dampen resonances (at least major ones, minors are probably fixed by dsp?).
How to determine those points?
Do tou have a NDA for the suggestion of improvements you have given? Do tou mind sharing the concept?
How to determine those points?
Do tou have a NDA for the suggestion of improvements you have given? Do tou mind sharing the concept?
No clue. Again, I'm not an engineer. I'm sure there's plenty of people on here that could spit that info out in a second. Seems pretty standard stuff, 1/2, 1/4 wave. As to how much and exactly where..? Probably some sorta modeling software somewhere that'd do it.
As for my improvements, they involve their proprietary investments, not at liberty to speak of.
As for my improvements, they involve their proprietary investments, not at liberty to speak of.
Nothing particularly difficult to follow about it as far as I can see -either simulate or measure a prototype of the intended line, and at the acoustic length corresponding to your harmonic mode peaks, add said mildly damped vent. You'll probably lose a small amount of overall efficiency, but it should help damp those off.
Whether it's actually worth the effort or not relative to other options is open to question. Probably not, although it seems valid enough. In a sense it's distantly related to Fulmer's progressively distributed terminus.
Whether it's actually worth the effort or not relative to other options is open to question. Probably not, although it seems valid enough. In a sense it's distantly related to Fulmer's progressively distributed terminus.
Any refs? Immediately reminded me of the tunable Karlson vent on the iBIB.
And certainly, the long skinny vents in my miniOnkens add R, ie damping, to the vent.
dave
I thought you knew Norman Fulmer's patent? US 2,787,332. About 9 months after Karlson filed his first coupler, although different application -in Norman's case it's really just a progressively distributed vent / termini location on a QW, same as you did with iBIB. IIRC our friend Steve Deckert did the same on his old MG944 before he chucked the Fulmer slot & replaced it with a down-firing PBR for the final year or so of its production (wonder how happy its suspension was, long term...)
