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Old 27th March 2013, 01:50 PM   #21
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Quote:
Originally Posted by jbell View Post
If you find my thread on the 'stadium horns' that I built using 3015lf's, you'll find a real 30hz option... and several posts about the whole BFM mess. Stadium horns are anything but portable, and you can only drive them to 50v or so safely. The SS15 is the 'balanced' option between loud and low, that's really the best bet in my opinion.
I was compelled to look this up since I hadn't seen it. Looks pretty awesome and reasonable to build! 50% larger gross volume than a t48, correct?

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Old 27th March 2013, 02:07 PM   #22
tb46 is offline tb46  United States
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Hi Robin N Zone,

Post #17: "...
Ive seen references to the Furysub, but all links to it have been dead..."

You'll find the furysub in this thread: LIVE SOUND Specific Tapped Horn thread... . I don't remember if the one in Post #536 was the last drawing, but it should be close enough. It's a good thread to read through.

As to the SS15, it's the best compromise I've seen for the 3015LF, a slight improvement could probably be had by incorporating cone correction into this design: TH-18 Flat to 35hz! (Xoc1's design) , Post #562 and so on (I recommend this thread to anyone who is looking for an extended range PA TH). Maybe jbell has some aditional information.

Hornresp does not indicate the losses at high power levels, according to the experts that have actually build and measured both bass-reflex and tapped horn enclosures that is where the TH really shines. In other words, if you want to know you got to build both, and measure (preferably outdoors, @ 10 meters w/ 100W, e.g.: like Danley).

Gotta run, Regards,
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Old 27th March 2013, 04:22 PM   #23
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Originally Posted by tb46 View Post
Hornresp does not indicate the losses at high power levels, according to the experts that have actually build and measured both bass-reflex and tapped horn enclosures that is where the TH really shines.
TH "shine" with stiff cones, but have lots of losses with lightweight cones like the 3015LF.

In post # 1492, “Single sheet TH challenge”, Crescendo measured his 3015LF loaded, 1/2” Aruco plywood SS15 cabinets at:

70Hz: 103.2 dBC, 2.83 v at one meter
70Hz, 124.7dBC, QSC PLX3402 amplifier “just at clip” ( about 75 volts, 700 watts at 8 ohm)

Had there been a linear voltage in/SPL out relationship, 700 watts/75 volts would have resulted in about a 28.5 dB increase in SPL, 131.7 dBC.

The cabinet fell far short of 131.7 dBC.
131.7-124.7 = 7 dB of power compression.

What % of power compression is from voice coil heat, exceeding Xmax, cone flex, or wood deflection is conjecture.
On a (presumably) short test, the voice coil should not heat much, exceeding Xmax, cone flex and wood deflection are the more likely dominant compression features in Cresendo’s test.

Tom Danley mentioned a 3 dB under prediction measured loss in the upper range of a large, multiple 18” cabinet. It required stepping up from 3/4” to one inch Baltic Birch with more extensive bracing to get the SPL up to the predicted level. Ended up weighing a lot more than the prototype.

Jim (jbell, the SS15 designer) mentioned some 3/8" deflection of the SS15 front panel at high power, that could amount to almost half of the measured upper power compression losses.

The reduction in the SS15 level at high voltage seems even worse than the FLH results shown in post #13 of this thread.

As Jim has mentioned before, the SS15 was designed to be efficient, lightweight, and quick to build.
It succeeds on those counts.

Art
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Old 27th March 2013, 05:03 PM   #24
jbell is offline jbell  United States
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turbodawg:
Oh man... I'd completely blanked that train wreck of a conversation out of my mind... thanks for the 'way back'

Art: (weltersys)

Yep, those measurements that you mentioned (here and in the past) show a bunch of compression. I usually run out of gas at 128 - 128.5... no matter what I do to the ss15 with a 3015lf, that's about where it runs out of gas... with the construction methods that I choose to use. Because of that, I've moved on to an ss18... but it's something that deserves it's own set of detailed plans, instructional video, etc... so probably not something that is a DIYaudio topic, more of it's own website topic.

Where the OP has 3015lf's... and the ss15's successes are pretty well documented on DIYaudio, as well as other boards -- it's the best chance of success I know of in this particular case.
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Old 27th March 2013, 09:49 PM   #25
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Quote:
Originally Posted by jbell View Post
Because of that, I've moved on to an ss18... but it's something that deserves it's own set of detailed plans, instructional video, etc... so probably not something that is a DIYaudio topic, more of it's own website topic
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Old 28th March 2013, 12:15 AM   #26
tb46 is offline tb46  United States
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Hi Robin N Zone,

As jbell is bringing up the "SS18" maybe I should add to what I said in Post #22: if you put your 3015LF into Xoc1's design for an 18" woofer you'll have a very nice TH. Naturally, it'll be bigger than the SS15 but it will reach a little lower. By the way, in that big a box don't run the input into the 3015LF past eg=45V with the 32Hz/24dB/octave LR high pass that jbell recommended in Post #19, at that input level the speaker just exceeds Xmax (on paper), and as weltersys already pointed out any additional input power will not buy you anything (well, maybe distortion, torn diaphragm....).

I'll attach some Hornresp screen prints:

Regards,
Attached Images
File Type: jpg TH18_3015LF_Input.jpg (39.4 KB, 292 views)
File Type: jpg TH18_3015LF_SPL.jpg (30.1 KB, 265 views)
File Type: jpg TH18_3015LF_Excursion.jpg (24.3 KB, 262 views)
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Old 28th March 2013, 01:13 PM   #27
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While I'm just randomly throwing ideas out there, the Cubo Sub also came to mind:

Tony Gee did it, it's on Data-bass...should I do it?

Here's a measurement of a cubo sub vs. 30hz tuned BR design. Both are 300L and use a Precision Devices PD1850. Much more below 35hz from the BR, but the Cubo is +5db sensitive from 40-100 hz+. More discussion in the linked thread.

Best sub

Click the image to open in full size.

Here it is against a more conventional kilomax driver:

Click the image to open in full size.

Last edited by turbodawg; 28th March 2013 at 01:16 PM.
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Old 28th March 2013, 08:00 PM   #28
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+1!
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Old 30th March 2013, 10:49 PM   #29
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Hello Guys!

Sorry I havent answered for a few days, work got in the way..

Ive been trying to read as much as I can on the SS15 and other designs suggested here, there sure is a lot to read

I really like the SS15, feels like a very good alternative to my T48s. But, I wouldnt mind to go a bit lower than the SS15, 35hz would be nice But then Id need a bigger box..

Like JBell says, the SS15 seems like a very good compromise for the 3015LF

tb46, I like the ideas that popped up here about cone corretion, gonna read up a bit more on that Is that something that someone has tried?

Is there something like a "final" drawing of the SS15, is that the one that is linked in the first post of the single sheet challenge thread?

Jbell, I see that you often used to say something like the T48 is 10-13db down at 40hz compared to 100, but alot of measurements of the SS15 seems to tell the same story? about 10db down at 40? But there seems to be different measurements and a bunch of different simulation curves?

I just want to be relatively sure that Id get the same or better performance from a pair of SS15s as I get from my pair of T48s I do understand that Ill loose some 100hz bass, but that doesnt matter, I always eq that area down anyways

If I can get very similar performance in a cab half the size, that would be truly fantastic If I even can get a bit more 40-50hz that would be amazing Id be able to bring 4 SS15s in about the same packspace as my 2 T48s, so should be able to go louder

The consensus seems to be that the SS15 is the best compromise cab for the 3015LF

Have anyone compared the two directly? Maybe it comes later in the SS thread, have only read about 70pages.. I thought it was interesting to see that Dave Non-Zero (who I "known" from the BFM forum) liked the SS15, I guess he actually compared them.

Jbell, you mention that your Stadium horn goes to 30hz? But Ive seen you write 40hz in your thread about them, did that change?

If one crosses a SS15 at 32hz, will there be any noticable output at 32-40hz? I see that the response drops rather sharply at above 40hz? Maybe if I run 4-6 of them in a cluster?

tb46, Im gonna look into the Xoc1s design that you suggest in post #26, but it feels like something like that has to be the next project, with a better driver

I think I given up on going below 40hz with the drivers I have, so it feels like SS15 is the way to go for now The only question is which "version" to build:P What about handles in that cab btw, would it work with some normal dishhandles or cornerhandles? How have those of you that have built them done?

Thanks again for all answers guys! So much to read on this forum

//Robin
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Old 31st March 2013, 10:23 AM   #30
epa is offline epa  Netherlands
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here is another option for the 3015
3015lf TH @ 35-40hz but only 20" deep help
Quote:
If one crosses a SS15 at 32hz, will there be any noticable output at 32-40hz?
the problem is that excurion risez rapidly under fb ,so a hpf to low is going to distort/destroy the driver.
the model in the above topic has much less cr (puting less stres on the cone)and is tuned lower@the expnce of lower output.
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Last edited by epa; 31st March 2013 at 10:42 AM.
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