Study structural engineering, though my SWAG without reading the thread is that 'overkill' due to minimal education on the subject is mostly at play here. Nicely done though.
Me and others have posted extensively on cab rigidity Vs mass loading to attain an acoustically inert cab for the different frequency ranges.
GM
Me and others have posted extensively on cab rigidity Vs mass loading to attain an acoustically inert cab for the different frequency ranges.
GM
Duly noted GM....I've been advised over again that 3/4 is adequate. Mass loading is new to me but I understand. My 3 ways are strapped to their stands and I immediately noticed the improvement in sound quality vs before.
Maybe the added material in the build is their way of adding mass?
Maybe the added material in the build is their way of adding mass?
Stiffness goes up at the cube of thickness, so while it makes it heavier it's not mass loading per se since the mass is ~ evenly spread out as opposed to using it to add compression loading like you did strapping them down; big difference.
Don't remember the math, but doubled up void free 18 mm ply is so rigid that no bracing is required until a cab gets quite large and even then just needs basic cross bracing.
Of course at some point the cab becomes so massive that compression loading has no impact unless needing to be designed for seismic events such as rambunctious teens, large dogs, etc.. 😉
GM
Don't remember the math, but doubled up void free 18 mm ply is so rigid that no bracing is required until a cab gets quite large and even then just needs basic cross bracing.
Of course at some point the cab becomes so massive that compression loading has no impact unless needing to be designed for seismic events such as rambunctious teens, large dogs, etc.. 😉
GM
Earlier in the thread I posted a link to this project, but deleted it for the same reason 🙄
If WAF is an issue, exchange the W 😀
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You may want to consider building modular cabs.
Makes moving easier and allows experimenting with a TMW or MTW setup.
In the latter case you'll probably need stands.
Makes moving easier and allows experimenting with a TMW or MTW setup.
In the latter case you'll probably need stands.
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Gary Dahl built a 'Beyond the Ariel' system, that has a few things in common with your plans.
He used an Azurahorn and experimented with the TD15M, but eventually opted for the GP416.
That thing on the side is a passive radiator.
Here's his photobucket.
He used an Azurahorn and experimented with the TD15M, but eventually opted for the GP416.
That thing on the side is a passive radiator.
Here's his photobucket.
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Like the previous image, this was his initial setup with both TD15M and TD15H.
The phase plugs are visible. Compression driver is a 745BePB.
The 'Beyond the Ariel' thread is worth scrolling through. It's awfully long... for a reason.
If I had to mention one thread in which 'it all comes together', it would be that one.
The phase plugs are visible. Compression driver is a 745BePB.
The 'Beyond the Ariel' thread is worth scrolling through. It's awfully long... for a reason.
If I had to mention one thread in which 'it all comes together', it would be that one.
Attachments
The reported 'problems' with the TD15M are probably a thing of the past.
Here are some measurements.
Here are some measurements.
Attachments
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In this part of the thread differences between woofers are discussed, also in relation to different types of music.
Thank you all so much for the research...I read when I can, I’ve been so busy with work, pulled 14 hrs yesterday, most days no less than 12hrs. Combined with family I’m slightly short on time. My life until November when I’ll be free for 6 months, life of a road construction worker ����*♂️
I didn’t figure out what problems the 15m had, yet...must be the resonance in the impulse you are referring to ����*♂️
Modular design is potential. I did buy 2509 jbl horn mounts, I’d have to find a creative way to try a mtw config. Tmw, was the main idea.
I wonder what advantage the AE 18h has over the 15h, the 15 has more extension and output according to modeling, less group delay also.
Tractrix vs jmlc, any opinions on that...the reading I have didn’t do much to explain sonic differences between the tractrix, circular and jmlc
Almost there!
I didn’t figure out what problems the 15m had, yet...must be the resonance in the impulse you are referring to ����*♂️
Modular design is potential. I did buy 2509 jbl horn mounts, I’d have to find a creative way to try a mtw config. Tmw, was the main idea.
I wonder what advantage the AE 18h has over the 15h, the 15 has more extension and output according to modeling, less group delay also.
Tractrix vs jmlc, any opinions on that...the reading I have didn’t do much to explain sonic differences between the tractrix, circular and jmlc
Almost there!
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Yes!!! I've been quite sure that JBL components must have been used here. Wonderful!
I guess there aren't any enclosure plans available?
Best regards!
I guess there aren't any enclosure plans available?
Best regards!
If I remember correctly, the phase plug, or the surround of the 15M supposedly was the source of some resonances.
I don't think this is a deal breaker, especially if you intend to cross low.
Gary eventually used the GPA416, but I believe his decision was largely based on subjective preference > He's a classical musician/conductor.
Personally I would stick with the 15M/15H combo.
The sonic differences between (round) Tractrix and JMLC horns will be subtle compared to constant directivity horns.
For a given mouth circumference the Tractrix will load the driver better, because the mouth of a JMLC is effectively smaller.
A large part is taken up by the roundover.
With a JMLC you'll almost inevitably end up with a multiple horn solution, or a higher crossover point > like Gary's system.
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No, don't hold your breath. Yours for $30k though.
But just a big monkey coffin so shouldn't be too complicated to replicate.
Check this out: YouTube
PBN M2!5 speaker uses two 15-inch JBL 2235H woofers which are completely rebuilt by PBN + the JBL M2 horn & JBL D2430H compressor driver combo for frequencies over 900Hz. The filter slopes are 30dB per octave.
You beat me to it, was just going to edit my post saying that.
How have the 2235H's been "completely rebuilt"? Sounds like marketing speak.
Hello Ro808
I doubt they are using 5 order electrical probably 3rd + 12db acoustic especially on the waveguide. Also look at the impedance curves. Where is the reflex loading for the 2235's? You can't see the double hump or the saddle at FB??
Rob
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There's a rule of thumb, which usually distinguishes technically advanced concepts with perfect measurement data from similar loudspeakers that were developed with the acoustic perception in mind.
Never use a woofer with a MMS >80g above 500Hz.
There's much more to this statement, but it basically comes down to the handover between the woofer and the, preferably 3", compression driver diaphragm.
You don't need a PhD in physics to 'see' why a 120g cone crossed to an 1.75" diaphragm is a recipe for 'shortcomings' in the midrange.
Never use a woofer with a MMS >80g above 500Hz.
There's much more to this statement, but it basically comes down to the handover between the woofer and the, preferably 3", compression driver diaphragm.
You don't need a PhD in physics to 'see' why a 120g cone crossed to an 1.75" diaphragm is a recipe for 'shortcomings' in the midrange.