Is it possible to cover the whole spectrum, high SPL, low distortion with a 2-way?

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mark100

Member
Joined 2010
camplo said:
Open baffle designs have shown that the drivers be mounted close to with no issues. Heck the formula for the OBSL is 1/4 length of diaphragm width equals slot width...I'm also just about 1/2 length and the testimony in PPSL thread on the subwoofer forums have testimony of various designs within these ratio with no issue....I feel an approximation of the effect can be modeled by halving the csa.
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What kind of slot are you using?

I've been talking about a slot such as djk post #10 A Thread for those interested in PPSL enclosures

Or like i built
ppsl 18n862.jpg
 
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mark100

Member
Joined 2010
Thx again ! That's my neighbor's yard in the background.
Yes, it is a bit of a DIY paradise...i feel quite lucky...
...and particularly blessed to have a girlfriend who happily endorses the hobby :)

I like the CBT best indoors, and the straight line outdoors.
It's pretty cool to steer the straight line's sound to come from the top, makes for a nice small party PA.
The CBT is the most room & placement tolerant speaker i've encountered.
 
weltersys

weltersys

Member
Joined 2008
camplo said:
Originally Posted by gedlee
Thanks Art - unquestionably the simplest approach that I have seen in this regard. Buy a premade large horn and just add some woofers to the sides - how much simpler could it possibly get!!
Is it simple? I guess you could use horn resp to envision some aspects considering cavity volumes and hole size....but someone did tell me that the holes should be as far away from the throat as possible.
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Simple? If you find Hornresp and using DSP to correct frequency response to be simple, perhaps.

Putting multiple entry exit holes closer to the horn throat will affect high frequency response to a larger extent than if located further away.

"As far away from the throat as possible" and still achieve even off axis polar response requires the exits to be within 1/4 wavelength of each other at the crossover frequency.
At 450 Hz (achievable with HF drivers and horns you are considering) that puts the hole centers about 7.5" apart. With 90 degree side wall angles, the distance from the horn throat or diffraction slot about 5", far enough out even 15" drivers may be used without "messing up" the high frequency response.

Art
 
camplo

camplo

Member
Joined 2019
GM said:
Historically, true woofer systems have been power [Xmax, box size and last, but not least, 2nd order harmonic distortion] limited to ~ 2 octave alignments, so you tell us. ;)

GM
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I was hoping to get a passionate opposition so I could let them know how I told the make of the speaker how his 15H is a better suited subwoofer because someone told me so, and the maker said that they are wrong and the 18H+ is better than the 15H in everyway.
 
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camplo

camplo

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fluid

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Joined 2009
camplo said:
I was hoping to get a passionate opposition so I could let them know how I told the make of the speaker how his 15H is a better suited subwoofer because someone told me so, and the maker said that they are wrong and the 18H+ is better than the 15H in everyway.
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Some of the comments on which drivers are best suited for certain things depends a lot on the box that they are going to be used in and would not then transfer exactly the same to another enclosure type.

Clearly the 15H does not make a better subwoofer than the 18H+, the 18 has more volume displacement. There was a vented alignment in which the 15 wanted to go lower than the 18 as I simulated it myself but in a sealed cabinet things are different.

I put the UM18-22, (Yellow) the TD18H+ (Blue) and TD15H (Green) into BassBox and this is the maximum acoustic power of each. You can see at 30Hz and below the Ultimax has 3dB more potential output.

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camplo

camplo

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Joined 2019
Only a 3db advantage over a midrange driver? Either the Ultimax is a below average subwoofer or the 18h+ is a super performing midrange that can do subwoofer duty.....hmmmm. I will say that a lot of the guys who critique this aspect, they have extension goals that are beyond mine....so its kinda like saying "thats not a knife.....this is a knife"
 
camplo

camplo

Member
Joined 2019
Can't argue that...THis is an aspect worth arguing -> 30hz on up duty...who sounds better? 18H+ does...
I will admit, the more I look at the chart above, the more I see where you guys are coming from. Yet I understand, and desire no change, is all.
Together, we can make this work, but slot loading is not going to make or break this design.

And I displayed ratios backwards above 4:1 and 2:1.
 
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nc535

Member
Joined 2011
BTW here is my slot loaded woofers plus horn concept drawing.

Each woofer box has a sealed TD15H and was designed to minimize CTC when used with a horn. I made the slots V shaped and got the TD15s to play past 600 Hz.

While I built the woofers and am using them in my TV setup, I never built the horn.
 

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mark100

Member
Joined 2010
Ro808 said:
And how does it compare to:
1. Your B&C 15cxn88
2. Your 100Hz two-way synergy?

It's apples and oranges I know, but I think some of us are curious about subjective opinions based on experience :)
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Thx to you and GM for the interest / for asking...

I view the line arrays, either CBT or straight, as different animals than the group of speakers I'd put in "point source" category. I kinda see them as sounding halfway towards an omni type sound. If i was into home theatre, I think the corner lines would work great both focus to a sweet spot and provide wider seating coverage.

The 15cxn88 coax is a nice sounding, fairly compact solution. I believe it and other prosound coaxs are best suited for musician's floor monitors.
Very close to hi-fi, but just not quite at the level of a separate horn and CD mated with whatever cone.

The 100Hz synergy, in it's last incarnation, a 60x40 sized for about 300Hz control, is the most gripping speaker I've built (or heard) yet.
It's just too damn big and heavy to move around like I like, so I'm currently working on lighter 90x60 build. The 90x60 allows a lighter box design, but so far it doesn't have quite the magic of the 60x40. I'll need to finish getting a secondary flare working on the new guy, to see if I can live with it.

Circling all the way back to my beginnings with DIY tops/mains....the Peter Morris PM90 and PM 60 are still two of my favorites, both indoors and out. I've used the 90 degree version for live events for several hundred or more folks, and they are very hi-fi. The MTM hornloaded 12"s around a CD, really works.
But so do other modular designs I've tried that use the same same CD & wavequide , but in separate boxes for the sections. Sometimes with one 12", sometimes with two.

I really think the most pragmatic way to get the SQ, dynamics, and SPL that I enjoy into one box, is some kind of MTM using a very good CD & waveguide.
I believe copying the new Meyer X-40 that uses a pair of 8"s in a simple MTM config would be a smart build.

Oh, and a biggie in all my DIYs, even including the line arrays...
everything gets a sub....all have been designed for 100Hz xover.
my 2 cent experiences...
 
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