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JTR Noesis 212RT Measurements

Jon AA

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tuga

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pozz

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The horn looks as crude as it gets, square with flat sides. Mid-fi at best.
It's a constant directivity horn, as seen in the measurements.
 

pozz

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You mean a Gueddes waveguide?
The manufacturer calls it a horn.

http://jtrspeakers.com/noesis-212rt.html
Geddes' design is called an oblate spheroid waveguide due to the shape. The difference between a horn and a waveguide is largely semantics, but generally a horn is used for acoustic loading while a waveguide is used to control directivity. This doesn't mean that one can't be the other.

The JTR design looks like a Don Keele-influenced model.
 

q3cpma

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For those who haven't seen it, Matthew Pose reviewed and measured these speakers here: https://www.avnirvana.com/threads/jtr-noesis-212rt-review-and-measurements.6779/

I figured quite a few people here would be quite interested in seeing the results. Very interesting speakers. I think Matthew does a pretty excellent job of measuring considering no anechoic chamber or Klippel.
A two way going down to -3 dB @ 35 Hz? I'd like to see some distorsion measurements. Looks like there are some resonance at 6~7 kHz too. And is this me, or the baffle step is strangely high for such a big speaker?
 

pozz

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A two way going down to -3 dB @ 35 Hz? I'd like to see some distorsion measurements.
Looks like a transmission line design as well, but I'm just guessing based on the bass response and position of the front port.
 

tuga

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I believe the correct name would be a pyramidal oblate spheroidal waveguide. :p

Except that the whole throat looks flat up until the mouth, unlike Geddes OBS:

Hero_NOESIS-210RT.png

jjip9lo.jpg
 
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Jon AA

Jon AA

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For those interested in it's design for bass (ported) and want to see distortion measurements, I don't know of any for this specific model but Ricci at data-bass has measured its big brother, the 215RT (measuring the bass like it was a sub): https://data-bass.com/#/systems/5c2656621cefb00004803ab3?_k=x80ath

That's a bigger speaker but should inform one on the validity of the design.
 

tuga

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He would mean a constant directivity horn, from Keele's paper.

This one (cross-section)?

9BeJoEd.jpg


There's a flange at the mouth but it seems to be missing the exponential expansion bit at the entry of the throat.
 

tuga

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For those interested in it's design for bass (ported) and want to see distortion measurements, I don't know of any for this specific model but Ricci at data-bass has measured its big brother, the 215RT (measuring the bass like it was a sub): https://data-bass.com/#/systems/5c2656621cefb00004803ab3?_k=x80ath

That's a bigger speaker but should inform one on the validity of the design.

They're only measuring the woofer/bass.

I think that the problems lie in the upper-midrange and treble, this waviness above 3kHz:

full-png.30942

source: https://www.avnirvana.com/threads/jtr-noesis-212rt-review-and-measurements.6779/
 

direstraitsfan98

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Very popular home theatre speaker. Then again, so is Klipsch...
 
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Jon AA

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They're only measuring the woofer/bass.
Yes, that's what the questions I was addressing were asking about.
I think that the problems lie in the upper-midrange and treble, this waviness above 3kHz:
I agree, if you're looking for flaws that's where you would point. I'd venture to guess some of that is being introduced by the horn/waveguide, but I'm not well versed enough in horn/waveguide design to speculate on any details. Some could also be some of the common issues with concentric drivers at high frequencies.

Regardless, when the "waves" are high-Q and less than +/- 2 db on axis, their audibility is questionable.
Mid-fi at best.....Home theatre has different requirements and less demanding expectations.
If you're aiming for the "Audiophile snobbery" award for the day, comments like that will make you a lock. :p

There are a lot of people using these for 2-channel systems as they are quite popular with people who prefer narrow dispersion and like extremely high dynamic capabilities. I thought you were a fan of narrow dispersion speakers? You may actually love the way these sound.
 
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Jon AA

Jon AA

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Looks like measured performance is better than JBL HDI series. SPL capabilities should be higher as well.
Yeah, that would make for an interesting comparison. The HDI's have a wider horizontal dispersion, but the shape of the curves is remarkably similar, with the JTR's just being lower in volume as you get farther off axis.

Of course, SPL-wise, the JTR's are on a different planet.
 
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