• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

JTR Noesis 212RT Measurements

Jon AA

Senior Member
Forum Donor
Joined
Feb 5, 2020
Messages
313
Likes
659
Location
Seattle Area

tuga

Major Contributor
Forum Donor
Joined
Feb 5, 2020
Messages
2,731
Likes
2,731
Location
Oxford, England

pozz

Data Ordinator
Forum Donor
Editor
Joined
May 21, 2019
Messages
3,711
Likes
5,826

pozz

Data Ordinator
Forum Donor
Editor
Joined
May 21, 2019
Messages
3,711
Likes
5,826
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

Major Contributor
Joined
May 22, 2019
Messages
2,984
Likes
4,018
Location
France
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

Data Ordinator
Forum Donor
Editor
Joined
May 21, 2019
Messages
3,711
Likes
5,826
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

Major Contributor
Forum Donor
Joined
Feb 5, 2020
Messages
2,731
Likes
2,731
Location
Oxford, England
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
 
OP
Jon AA

Jon AA

Senior Member
Forum Donor
Joined
Feb 5, 2020
Messages
313
Likes
659
Location
Seattle Area
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

Major Contributor
Forum Donor
Joined
Feb 5, 2020
Messages
2,731
Likes
2,731
Location
Oxford, England
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

Major Contributor
Forum Donor
Joined
Feb 5, 2020
Messages
2,731
Likes
2,731
Location
Oxford, England
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

Addicted to Fun and Learning
Forum Donor
Joined
Oct 1, 2018
Messages
826
Likes
1,162
Very popular home theatre speaker. Then again, so is Klipsch...
 
OP
Jon AA

Jon AA

Senior Member
Forum Donor
Joined
Feb 5, 2020
Messages
313
Likes
659
Location
Seattle Area
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.
 
Last edited:
OP
Jon AA

Jon AA

Senior Member
Forum Donor
Joined
Feb 5, 2020
Messages
313
Likes
659
Location
Seattle Area
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.
 
Top Bottom