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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 7th April 2019, 12:16 AM   #131
Robh3606 is offline Robh3606  United States
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Quote:
RobH:

I need to understand this in a slightly different light; if you run the 2344a full range without any type of compensation, and just let it roll off, would a simple high pass protect the 2404H from damage? High passed at a higher level, as many suggest on the Lansing forum...say 7-8khz?

Thanks!
It might work but you really need to either sym it or try with DSP or an active set up. Passive is hit or miss and without measurements and a good crossover sym program it may be doable but it's going to end up being trial and error to get there. No matter what, you need to work out the attenuation for both the 2344 and the 2404 or you won't be able to get them to sum properly

Rob
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Last edited by Robh3606; 7th April 2019 at 12:19 AM.
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Old 7th April 2019, 12:34 AM   #132
turnitdown is offline turnitdown  United States
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To answer your question, yes, you can let the bigger horn run, but your curve will be disappointing. You can run a 2404 with just 2uF, run the 2344 full open and not hurt the 2404.
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Old 7th April 2019, 04:21 AM   #133
norman bates is offline norman bates  United States
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500hz ?
For the pt ?

I think they only "load" to 1200-1500.
The newer pt is 3" deep.

Eek, i wouldn't cross my 2384 (way bigger horn) with 2435hpl below 750hz.

Your 4" diaphragm may get there, idk.

Thanks for all your work.
It takes a bit.
And graphs with the same compression different horns show much.

Last edited by norman bates; 7th April 2019 at 04:43 AM.
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Old 7th April 2019, 06:25 AM   #134
DualTriode is online now DualTriode  United States
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Norman,

Just speaking of test frequency band not crossover frequency. If you are crossing over at 1.2KHz ish you will be asking your CD / waveguide to perform sort of okay down to 500 or 600, an octave or so below your crossover frequency.

Thanks DT
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Old 7th April 2019, 06:11 PM   #135
norman bates is offline norman bates  United States
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Ahhhhhhhh, ok.

I think rob got his older pt horn plus 2435hpl (3" diaphram) down to 1khz with no eq boost, just hf boost for it.

Too bad the older pt is $150 while the newer is $75 (basically after shipping).

Foam around the older pt horn sounds really good to my ears.
It doesn't do much wrong at all.

Norman
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Old 15th April 2019, 06:17 PM   #136
DualTriode is online now DualTriode  United States
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Hello All,

Had a good couple of days testing things, would have tested more but went to the beach instead.

Tested TS / P for several woofers trying out for the woofer job in my new mains project, results are saved on a thumb drive. See the sample curves and TS /P for the 2204H.

Tested impedance with the PT H1010HF-1 waveguide (the new one) with several drivers; 2432, 2451J and D2. I will post these in this thread.
Also tested the smaller version of the JBL Butt Cheeks the 2342 with a 2425HS driver. I will also post this one.

One thing worth noting is that the impedance plots for the cone drivers and CD / waveguide look completely different. In my head this helps explain the reason that cones and horns sound different.

Similar to the cones all of the CD / Waveguides have what I call a voice coil impedance / resonance peak. The CD / Waveguides also have what Rob calls a Throat Mouth impedance / resonance peak.

Another thing in the CD / Waveguides curves absent in the cone curves is what I call Micro Resonances. At first glance they look like sort of random saw teeth. I plotted and replotted the CD / Waveguides curves many times on the same graph. Each plot fell exactly on top of the previous plots with each MR exactly matching the previous plots. These MRs are not random noise or artifact.

Attachments are:

JBL 2204 H impedance curves; in air and with added 93.5 gram weight and TS / P table.

JBL PT H1010HF-1 with JBL 2432H driver; Full band width and zoomed in 1K to 4KHz.

Thanks DT
Attached Images
File Type: jpg Impedance Magnitude.JPG (86.5 KB, 129 views)
File Type: jpg Thiele-Small.JPG (51.9 KB, 135 views)
File Type: jpg Impedance Magnitude 2.JPG (78.5 KB, 124 views)
File Type: jpg Impedance Magnitude Full BW.JPG (71.4 KB, 130 views)
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Old 15th April 2019, 06:21 PM   #137
DualTriode is online now DualTriode  United States
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JBL 2451J
Attached Images
File Type: jpg Impedance Magnitude 1.JPG (66.8 KB, 130 views)
File Type: jpg Impedance Magnitude Full BW.JPG (68.2 KB, 33 views)
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Old 15th April 2019, 06:22 PM   #138
DualTriode is online now DualTriode  United States
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JBL D2
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File Type: jpg Impedance Magnitude.JPG (79.7 KB, 45 views)
File Type: jpg Impedance Magnitude Full BW.JPG (69.0 KB, 38 views)
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Old 15th April 2019, 06:24 PM   #139
DualTriode is online now DualTriode  United States
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JBL 2342 Smaller Butt Cheeks
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File Type: jpg Impedance Real 1.JPG (67.4 KB, 44 views)
File Type: jpg Impedance Real full BW.jpg (69.1 KB, 39 views)
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Old 16th April 2019, 04:29 AM   #140
Robh3606 is offline Robh3606  United States
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Quote:
I think rob got his older pt horn plus 2435hpl (3" diaphram) down to 1khz with no eq boost, just hf boost for it.
Hello Norman

I don't use "hf boost" like you would use in a Pro S/R set-up. There is no reason to in a home application as it really is a worst case scenario for a compression driver. Even my bi-amp setups use a passive compensation network.

When you use an active set-up with a CD compensation curve you can end up with 10db or more of boost up there to compensate for the mass break point roll off of the driver. It's no wonder some active set-up's really get harsh or glaring as the volume goes up.

The better way is to loose efficiency midband and use a passive network to reduce the lower end of the drivers response to match the woofer and get a "flat response" that way. You end up driving much less power into the compression drivers upper octaves, a couple of watts vs 10X as much if you go active boost.


Rob
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Last edited by Robh3606; 16th April 2019 at 04:35 AM.
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