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Multi-Way Conventional loudspeakers with crossovers

JBL PT 100x100 waveguides, any experience? MPro?
JBL PT 100x100 waveguides, any experience? MPro?
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Old 1st November 2018, 02:35 AM   #1
norman bates is offline norman bates  United States
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Default JBL PT 100x100 waveguides, any experience? MPro?

Newest one. JBL 442730-001 PTH1010HF-1 Waveguide - Speaker Exchange

Or even last gen before jbl "pt h1010hf" - Google Search

The mpro looks good too (patick bateman). I'm thinking about minimal colorations, as in no flat walls, no bent horn paths, no diffraction slot (parallel walls).

The newest waveguide seems like a winner.

Last edited by norman bates; 17th November 2018 at 01:18 AM.
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Old 14th November 2018, 10:04 PM   #2
DualTriode is offline DualTriode  United States
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Hello,

There is another thread that goooooes on about this and other stuff.

I will reply here.

What driver will you use with this horn/wave guide?

What is the low crossover frequency for a possible 2-way? I see that JBL used 1.6K for the original version of this wave guide>

I am thinking of 3-way with JBL 2123's Directivity may be close at about 2K crossover.


I have a pair of JBL 2451's to test drive with these wave guides that I ordered today.

Thanks DT

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Old 15th November 2018, 04:01 AM   #3
norman bates is offline norman bates  United States
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polars look nice till 8khz anyway.
https://www.jblpro.com/ProductAttach..._00-082016.pdf

I see it is a 1.5" throat (jbl 2432), but jbl uses it occasionally with a 1" with adapter such as the jbl 2408. But good question, I can't see going under 1.5khz, that would then lean towards 8's for dispersion.

I have a jbl 2407, but I not against other drivers.

Just where I am at, currently seeking reflection free horns that ideally don't beam like an exponential horn as the frequency increases.

Where is the other thread ?

I saw rob had the earlier pt h1010hf used in a 3 way.

Me, I'm thinking 2 x 8" crossed at 2khz.
Something of a higher output speaker but clean monitor for mid volume movies.


Norman
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Old 15th November 2018, 07:04 AM   #4
DualTriode is offline DualTriode  United States
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Hello I am looking to cobble together something that looks like a finished speaker. I do not expect this thing to ever be complete. Typically mid 80dBs In terms of volume but then 100dBs plus to shake things on occasion. I am also thinking of a sectioned front panel that can be removed and replaced in pieces with different midrange drivers and different tweeters including horn/waveguide variations as the mood changes.

Reflection free waveguides with short rapid flares sounds like a good idea to reduce diffraction and other distortions. I am also thinking of compression drivers with larger diaphragms that have larger air volumes behind the diaphragm to reduce the typical horn adiabatic nonlinear air compression distortion associated with horns. A faster flare rate in front the phase plug, a larger diaphragm and a larger air space behind the diaphragm adds up to a compression driver and horn with less compression and less distortion. Maybe? Stuff that I want to test.

Nice looking polars are a goal. Smooth, level and flat Directivity Index plots are nice. I wonder if level, dead flat constant directivity is necessary for optimal sounding speakers? I am thinking a smooth gradually sloping Directivity Index plot might be preferred. At least avoid discontinuous doglegged Directivity Index plots. The directivity should be set to the Goldilocks standards to allow just the right amount of space in the listening room.

Just some reflections of mine.

Thanks DT

Comments Thoughts?

The other thread.

1.4" or 2" throat large constant directivity horns you can actually buy!
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Old 15th November 2018, 09:16 AM   #5
AllenB is offline AllenB  Australia
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A flat and level directivity index will take a very determined effort to achieve. Smooth is definitely wanted.

In my opinion, getting it level is a sign of getting a lot of things right, for example focusing reflections behind you. At some lower point early reflections disappear, for example work out the first reflection frequencies. At the lowest frequencies directivity becomes a hazy issue, for example filling the room via its modes is the goal. Blending down to these points though can still require an acoustically large device.
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Old 16th November 2018, 01:20 AM   #6
norman bates is offline norman bates  United States
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I'm talking about reflections in horn path.

This would be reflection free.
Attached Images
File Type: jpg mcm round horn.jpg (9.1 KB, 900 views)
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Old 16th November 2018, 05:55 AM   #7
AllenB is offline AllenB  Australia
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I see your point as you explain in your first post. This would be a good waveguide by those guidelines. I think calling it reflection free is splitting hairs.

There are more fundamental parameters such as how well it can hold directivity down to some frequency. For this the choice can't be based on it simply not doing anything else wrong.
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Old 16th November 2018, 08:33 AM   #8
DualTriode is offline DualTriode  United States
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AllenB,

Please back up the cart and use more words to clearly tell us what you are talking about.

Directivity Index is defined and measured independently of the room.

Thanks DT
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Old 16th November 2018, 09:15 AM   #9
AllenB is offline AllenB  Australia
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Yes it is. I guess I've made the assumption that it is done in a certain way. What kind of DI are you thinking about.. narrow, as wide as possible while excluding early reflections, frequency restrictions?
Quote:
short rapid flares sounds like a good idea to reduce diffraction and other distortions.
I assume it doesn't make sense to let the directivity widen then narrow again, so a small waveguide is going to force wide directivity from a highish frequency down.

With regard to diffraction, a larger waveguide can reduce the issue as well by holding the wavefront until it can substantially support itself.
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Old 16th November 2018, 11:54 PM   #10
DualTriode is offline DualTriode  United States
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Quote:
Originally Posted by AllenB View Post
Yes it is. I guess I've made the assumption that it is done in a certain way. ...

I assume it doesn't make sense to let the directivity widen then narrow again, so a small waveguide is going to force wide directivity from a highish frequency down.

...
AlanB,

You are making a lot of assumptions; I do not know what they are. Please more words and clarity.

This thread started with the JBL PT H1010HF waveguide, JBL uses this wave guide with a crossover frequency of 1.6 Khz. That means any genital uphill slope in the DI vs frequency plot below 1.6K belongs to the cone woofer. From 1.6K up to 8K the DI plots provided by JBL look to be close to level and flat. Above 8K, with the data provided by JBL, it is hard to tell what is happening, other than an increasing slope.

JBL data sheet https://www.jblpro.com/ProductAttach..._00-082016.pdf

Thanks DT

Last edited by DualTriode; 16th November 2018 at 11:57 PM. Reason: add data sheet
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