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Discussion Starter #1
I came across these speakers on Monoprice, and hadnt heard of the design before.



"A unique cabinet design and a variety of existing speaker port technologies (acoustic suspension, bass reflex, and transmission line) have been combined in a way that simply defies belief! Low frequency sound waves travel through the internal cabinet into a specially designed chamber. This chamber amplifies the driver's backwave, significantly increasing the kinetic bass energy as the air is accelerated out of the vent. The result is that the frequency response is greatly enhanced and dynamic range is dramatically increased."



Anyone else heard of such a design?

Heres a link to the page: http://www.monoprice.com/product?c_id=109&cp_id=10904&cs_id=1090407&p_id=15952&seq=1&format=2
 

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Hi there,

I have seen a few odd once in my time yet this one does actually not make much sense!
It looks very much as a partitioning area were as this is working as a balancing / buffer part for the pressure in the enclosure (Extra volume yet separated & quiet similar working to an Air Intake on modern cars). The drawing seem to be misleading as well as there would be no way this would work in a way the arrows are drawn originally yet as a Buffer zone (air suspention like!) as the red arrows show.

rgs UpperCut
 

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Discussion Starter #3
I posted in this section, assuming folks in here would have the best understanding. And I completely agree, as a resonator or muffler of sorts such as an intake on a car, that makes total sense. But as for being able to do anything else, I just dont see it. Its a fairly small opening as well on the front baffle for the port. I wonder how wide that port is inside or how its shape may change.
 

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I posted in this section, assuming folks in here would have the best understanding. And I completely agree, as a resonator or muffler of sorts such as an intake on a car, that makes total sense. But as for being able to do anything else, I just dont see it. Its a fairly small opening as well on the front baffle for the port. I wonder how wide that port is inside or how its shape may change.
The front opening is keept smaller to load up the enclosure pressure I assume to give this inner port cloud to work as a buffer! Like I said before working as a kind off Air Suspention, but to do what it all claims ??? ..............

rgs UpperCut
 

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I looked at the FR & it looks like it starts rolling in the 40's. Not much different than other speakers than I can see.
 

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The site claims 39-20k. I think they're saying the big deal is because it's a single 5.25 hitting 39hz. My center has two 5-1/4's and it's only rated to 75hz. Whether or not it can hit 40 with any authority is another thing altogether, but it seems legit. Mostly...


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Discussion Starter #9
By the way, the beginning of the Atlantic Technology review can be found at http://www.stereophile.com/content/atlantic-technology-1-loudspeaker#VDByqXMU7bt22S4T.97

I take much of what Stereophile (and similar magazines) has to say with a large grain of salt, but the measurements can be useful.

Few
Wow I think you are right, appears to be a copy of the Atlantic idea. A comment below the review seemed very interesting as well, I'll quote them below, but it sounds as though its a technology done and tried many times over.

"The above speaker is a decent performer - for a bass reflex. However, there is nothing unique, patent worthy, or even new about the design. PMC has been using resonance traps in its speakers for years.The "patent" shows a tapered transmission line shape with an anti resonance trap whose opening is located at a pinch point within the line. The distortion measurements shown in the patent are as misleading as the marketing hype for this speaker - distortion figures are presented only for select frequencies to make it look better on paper than it really is. In fact, the impedance plot shows the telltale sign of an anti resonance trap - a impedance peak around 100hz. This is actually not a good thing. If you were to measure THD at that frequency, you'd find a noticeable increase. "Anti resonance traps" or acoustic filters have been around since the beginning of transmission lines. Their use actually demonstrates a lack of knowledge/skill in design - not an advancement.

Moreover, the claims of mixing bass reflex with transmission line are totally bogus. True transmission lines possess a gradual 12db per octave rolloff in the bass region below the transducer's Fs or fundamental resonant frequency. This speaker clearly does not. It's rolloff is representative of a reflex design (steeper 24 db/octave roll off below transducer resonance). Compare the low frequency response of this to that of the Vivid Giya "quasi" transmission lines:

http://www.stereophile.com/content/vivid-audio-g1giya-loudspeaker-measur...



What this AT speaker is is a bass reflex with a small horn attached to the port opening and an acoustical filter incorporated to help dampen the upper resonances of a primitive design. Phil is just warming over a 25 year old transmission line patent with the application of an internal restrictor.

Despite the false claims of this speaker's "designers", there is no continuum between a true transmission line and a pseudo "mass loaded transmission line". Mass loading means bass reflex - PERIOD. The velocity of low pressure pulses escaping a transmission line should be in the neighborhood of 340 m/s. The velocity of air transfer in most reflex designs is about 18- 20 meters per second (notice I said "air transfer" - not low pressure acoustical pulses - big, big difference). The mechanical tuning of a reflex design is centered about a Helmholtz resonance - a slug of air being forced through a restrictive pipe. The time it takes to ram the air slug through the restrictor determines the tuning frequency. With a transmission line, there is not supposed to be any "restriction" beyond the slight tapering of the cavity behind the speaker diaphragm that follows the natural reduction in acoustic pressure that occurs when sound radiates a given distance from its source (the 1/distance attenuation rule). The timing (frequency tuning) of a transmission line is established by distance from the source and the frequency whose peak presssure occurs at that distance. Contrary to now unfortunately common assertions, the two approaches can't be mixed. You either have restrictive timing and the inherent 24 db/octave rolloff or you don't.The design concepts are worlds apart and so are the results - particularly when you attempt to feed both designs with sub bass programme material at high volume. The reflex design unloads (over excursion) below tuning frequency and the transmission line just keeps humming along. The frequency response and impedance plots always give them away.


Read more at http://www.stereophile.com/content/atlantic-technology-1-loudspeaker-page-2#YTLDGxVmG7hP2ftH.99"
 

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The resonant chamber is supposed to be a trap tuned to absorb harmonics of the line's fundamental resonance. It's intended to reduce harmonic distortion. Phil Clements (Mr. h-pas) was doing the same thing in the late 1970s with his Phase Research speakers. You can take a look at some sales literature from those days for a bit more explanation (if you can see the images on the diyaudio site). See post #8 in this thread.

Also, there's a discussion among skeptics here.

Few
 

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Hi
While searching for an image, I discovered this page by accident.

Once upon a time I used to be an audiophile :). Now I'm reduced to FLAC recordings :)

To me, this speaker is NONE of the types claimed above.

It is not a bass reflex, as it does not have a tuned port per se, it does have an opening :) but this opening does not seem to be a tuned port of any kind.

It's not really a transmission line speaker as the "transmission line", if it could be called that, is too short, for the real effect of a transmission line.

It can't possibly be an acoustic suspension design, because there is NO sealed compartment containing a driver (with the rear of the speaker facing into the sealed compartment).

The lower section where the arrows show air flow in and out of a dead-end box, seems nonsensical to me. Air flow, if any would be mostly cancelled out by the mostly continuous flow from the rear of the bass driver. This design purports to have the air flow move around a 90° corner INTO a dead end box and "magically" come out again. Why would air flow in this manner when there is a direct and EASY flow out to the front of the speaker cabinet?

It may be a great sounding speaker but (IMHO) the description is just marketing hype to attract those that don't know any better (and that's not necessarily their fault, everyone has to learn somehow :) ).

I hope the intervening four years have been good to the original poster and a good pair of speakers are now in place :)

Regards

Peter
 
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