[Vengeance187]

I was going to put this in the DIY section since it would interest them more, but this forum says "should cover theory" so I guess it should go here.


Has anyone seen, heard of, or tried this?
http://www.google.com.ar/patents/US20120219171
It says you can tune a port higher to get lower extension, which would also make for a much smaller "enclosure".


"Prior art teaches that low frequency extension is achieved by tuning low, near the desired low frequency cut off. It is counter intuitive in prior art that low frequency extension could be achieved by tuning higher, above the operating band of the loudspeaker assembly.

Tuning higher to provide low frequency extension would have an advantage that the loudspeaker assembly may be very small. The loudspeaker may be made as small as desired to satisfy practical requirements including cost and space availability. In some applications it may be appropriate to make the loudspeaker assembly even smaller to achieve a desired response."


I would like to hear thoughts from the vastly more experienced than I on this subject.
It certainly seems interesting to have increasingly smaller enclosures for increasingly larger drivers for increased WAF.

 

[Mark Seaton]

What you linked to is a patent application, and I'd be very surprised if it was granted. All embodiments are bandpass designs with smaller chamber sizes. Sometimes useful, but long ago patented and now expired for all to use.

 

[Vengeance187]

It doesn't seem like a bandpass. For a bandpass it says "As front chamber volume(s) increase, the system becomes more efficient. As front chamber volume(s) decrease, system effiency decreases." which is the exact opposite of the patent claim. The patent says the chamber should be as close to zero volume as possible at full excursion.
For a bandpass it also says "The port MUST tune the front chamber to the exact center of the passband or the box will sound like total garbage." which is again nothing like the patent. The patent says the port should be tuned above the operating band. If this is how a bandpass works, do you know where I can read about tuning a port much higher for low frequency extension? I can't seem to find anything on it...

 

[Bill Fitzmaurice]

What you linked to is a patent application, and I'd be very surprised if it was granted. All embodiments are bandpass designs with smaller chamber sizes. Sometimes useful, but long ago patented and now expired for all to use.

It might be/might have been granted, but if so only by a very inexperienced examiner. In any event, if the port tubes shown in the diagrams are even remotely to actual scale the chuffing noise would render the speaker useless at other than very low power levels. Hoffman's Iron Law is still safely in force.