Jamo Concentric Port Patent....

[mrfeedback]

A few of the older members around here may remember a Jamo speaker from the mid eighties that featured a port arrangement concentric around the woofer.
Does any body have experiences and technical appraisal of this technique ?.

Eric.

Like this...

[qwad]

I'm truly surprised Jamo was granted a patent on this techique, as I recall our loudspeaker guru cousin from across the other side of the pacific had a cunstructional article in practical mechanics in approx' 1965 using a similar idea originally invented and developed by a gentleman called "Thouras" [ basically it was nothing more than Jamo's idea of distributed ports around the circumference of the bass driver] which only goes to show that there is nothing really new that hasn't been thought of before] although the spelling of the name may not be correct, I had a copy of the article up to about 10 years ago when in one of my clean up /rationalisiton frenzies threw it out as of no value to me personally it was about the time Jamo introduced their speakers, and as I recall wondering how they could claim a patent for the idea... either that or the patent office did not do a good job researching it ps; sorry for shouting purely unintentional I assure you cheers and best regards to all and sundry TC

[qwad]

nt

[mrfeedback]

The Jamo design is a single annular port/double tube around the woofer.
Do you have any references to the design that you speak of ?.

Eric.

[phase_accurate]

There was also an EV design for general sound reinforcement that had a reflex slot around the baffle, though nor round but quadratic. If you restrict this to two opposite sides only, you are left with an Onken cabinet.

As far as I remember Jamo claimed, that their principle would cause less tumbling of the cone due to uneven mechanical loading of the cone, back then.

Regards

Charles

[qwad]

to mr feedback, as the good professor (julius summner miller) would say; this may be so but the principle is still the same no? best regards to all TC

[Gregm]

Or lucid interval.

I seem to remember qwad's ref to Mr Thouras. A man of greek extraction it seems. But I had it, it had to do with what is now called dual concentric, or s/thing in that order... whatever.

Qwad: may the Magyars live indeed! How so? Are you one (if so, Udvozlom)?

Cheers

[jackinnj]

Jamo patents:
4,802,551 and 4,440,260
search under AN/Jamo (for assignee, Jamo) at www.uspto.gov

[kelticwizard]

I think I read somewhere that the original Helmholtz resonators had the driving element in the middle of a big hole. There was space around the driving elements.

The notion that the driver does not have to be located in the round hole, but instead could be mounted sealed in the box with a vent, came later.

So it looks like Jamo, with it's ring around the speaker, has really taken things, ahem ahem, "full circle".