JBL PT 100x100 waveguides, any experience? MPro?

sometimes they do ?

maybe it is the 12" not wanting to move.
maybe it is the amount of garbage coming out of the bottom 2 front triangle ports (a bit, but stuffed they seem to roll under 150hz).

Texture of voices, my 6" morels smoke them, especially on tori amos "little earthquakes" 7' away.
And at low volumes the solstice goes pretty low.

Maybe it is lack of lower bass with the am6212.
I need to run them crossed at 100hz.
Qts .32 and Fs 43hz, means ported would be 9db down at Fs (basically gone).
 
Hello Rob and Norman,

There are a pair of 100 X 100 JBL 2344 with JBL 2435HS (1 inch threaded attachments) here that I tried out as well. The 80’s look is cool.

I have these speakers stacked up in boxes so I can swap out the woofer, mid-range or tweeter. So far I have pretty much settled on the 2123 mid-range and the PT H1010H-1/2432H tweeter. I like the smooth transition of the beam-width/Directivity Index of the 2123/ PT H1010H-1 combination. I am closing in on the JBL 2204H as the woofer, it has a 1/3 octave better bass extension than the 2206, -3dB at 51Hz. For my small room I like the smaller footprint of the 12 inch woofer over the 15 inch 2235.

This setup is all active with a Rane AC 22S 3-way crossover and a Rane 30 band 1/3 octave equalizer. The equalizer is set with a 10dB tilt downhill with increasing frequency. This equalization is setup with a Rane Real Time Analyzer. Originally it was set flat, and then I did the math for the 10dB tilt and readjusted the slide pots.


Thanks DT
 
Well, I am only assuming.

Looking at the plane wave response of a 2431 (post 2)
2431h

then the overlay of the directivity of the pth1010 horn, well it does narrow a little past 4khz, so it may offset it.

It pinches (1010hf horn) down at 10khz, maybe that explains the 10khz notch in network.

So, yea, I guess it may measure flattish to 10khz. You can see a droop off axis at 10khz+.

Going to hook it up tonight (speaker).

I'm surprised jbl pushes it down to 1.2khz, horn doesn't seem deep enough, maybe it is.

Down the road I'd like to try 2431 with newest pt waveguide 100x100.
read that long snout compression drivers built more for long horns, like 2432 would work better with 2384 than the short pt waveguide.
 
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I'm surprised jbl pushes it down to 1.2khz, horn doesn't seem deep enough, maybe it is.

It seems to work out well below that. Take a look at what a large format 1.5" 4" driver does on it.

Rob:)
 

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Hello

In the fengshui of things that horn is too big for my space, I am downsizing; maybe for movie night out in the yard.

My listening room is sharing a large bedroom with my work benches. No more HT.

I like the semi-tower shape my speakers are taking with; woofers JBL 2204’s, JBL 2123’s and PT H1010HF-1’s.

Thanks DT
 

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Actually had a breakthrough.

Crossed at 100hz to my 2 eminence magnum 15lf, wow.

Watched horror movie "Mama" after cranking some bass stuff from "judgement night" and "romeo must die" soundtracks.

Now I'm impressed.

Now you are talking Low Frequency Effects.

GedLee recommends several subs to overcome room mode issues.

Low-frequency effects - Wikipedia
 
Yea, read a while back something that still resonates in me.

If a speaker is weak below 100hz, it is not sastisfactory long term.

It could be the sub (double 15 vertically stacked), it weakening the vertical standing mode of 9' ceiling.

There was an article long ago by klipsch showing heresy floor loaded vs away from wall and 2' off floor.
I remember 2' off floor response dropped below 200hz, small spike maybe 130hz then rolling down.
Granted, unless concrete enforced floor loaded, heresy is bass light.

Anywho, guess I'm a bass head. Before sub, i thought jbl sounded funny, constantly fiddling with eq.

I do have foam around mouth absorbing reflections.
 

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Hello Norman,

In your posted photo I see the “foam” you have placed partially obstructing the mouth of the waveguide.

The foam looks to be soft and absorptive to a degree. The foam also appears to be cut with square edges that are likely to be reflective to a degree as well. The sharp edges seem likely to also add a significant amount of diffraction.

The smooth waveguide factory surfaces appear to be the product high tech design and iterative testing. Do you have any documentation showing how the application of foam over the mouth of the waveguide is an improvement?

Thanks DT
 
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nope, my ears like it.

The pt waveguide is a very short horn, flare is very quick and rounded.
On the big 2384horn, the rounded over horn walls I believe made foam around the horn mouth less noticeable.
Like the highs just can't get around the bend, unlike a diffraction slot edge in the throat.

To be honesty, it helps, a little, not jaw droppingly, more like a strong subjective response to a better speaker cable.

I've been playing with foam like this (maybe 30ppi I think) for a long time around horn mouths.

I have better luck with felt with my dome tweeter (there is documentation on that), but I couldn't tell you how much it would be for a piece 1" or more thick 14.5" wide by 12.5" tall (F10).

here are some links on felt and its effects.
Diffraction Doesn't Have to be a Problem
Felt Rings verses Felt Blocks for Baffle Diffraction Reduction

and here are some of my experiments with foam and horns.
post 31 Felt or foam walled waveguide?
post 12 Stereo-Lab cf400/cf250 Tactrix or Jabo KH-55 Exponential Horn for Radian 950PB
post 11 Does anyone here think Waveguides are not a good idea?
post 1997 Does anyone here think Waveguides are not a good idea?

I don't measure, but I can send you some foam to play with.

My current jbl is using 2" foam (I think), very porous but you are right, it may be reflecting something, I doubt it after trying to listen through the foam, small effect.
 
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Your ears may like it, and that's important. As a proponent of 100x100 horns, I can't help but think you have shrunk the pattern, and, while introducing an artificial/non-design boundary on the horn, I can't help but think the full pattern of a smaller dispersion pattern horn run as it's supposed to be, might not be better in every way.



What do you think?
 
I bet the foam isn't doing much below 4khz.
I think of the foam is absorbing reflections hitting box edges and reradiating (probably see in a waterfall response) than narrowing dispersion in room.

I sit 7' away, so I don't notice a lack of off axis, the horn narrows past 8khz as do most 1.5" throats.

The horn itself isn't really 100 x 100, more than that then narrowing to that past 5khz (compression driver).
 

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