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Hey guys...we need a little rallying here... - Page 216

post #6451 of 9857
Quote:
Originally Posted by pgwalsh View Post

The slot port is 13" wide 1" tall and looks to go from start right from the bottom, so 3/4 from the bottom or perhaps a little higher. I PM'd Mike.

What about 2 slot ports separated by about 1"?

There's a vertical brace right in the middle of the cabinet. I can design that brace to come up off the bottom of the box to the height of the slot port.

This is a box for the smaller SEOS.




Notice that vertical brace. It could be used to divide the port in half, and then you could lay the top panel of the slot port right on there and glue it in place. All I would have to do is change the height of that brace leg to the height needed for the port.

I'm just taking a wild guess, but maybe two 6" wide slot ports that are 1.15" tall versus one 13" wide slot port that's 1" tall? What do you think?
post #6452 of 9857
Quote:
Originally Posted by Erich H View Post

What about 2 slot ports separated by about 1"?
There's a vertical brace right in the middle of the cabinet. I can design that brace to come up off the bottom of the box to the height of the slot port.
This is a box for the smaller SEOS.

Notice that vertical brace. It could be used to divide the port in half, and then you could lay the top panel of the slot port right on there and glue it in place. All I would have to do is change the height of that brace leg to the height needed for the port.
I'm just taking a wild guess, but maybe two 6" wide slot ports that are 1.15" tall versus one 13" wide slot port that's 1" tall? What do you think?



Sounds like a really good idea. What's the volume on that box?
post #6453 of 9857
That box is for the 10" models and roughly 1 cuft net. A 12" woofer will fit because that's also the box for Jeff Bagby's sealed Tempest. I think it's 10.75" deep with the outer baffle.
post #6454 of 9857
Quote:
Originally Posted by Erich H View Post

That box is for the 10" models and roughly 1 cuft net. A 12" woofer will fit because that's also the box for Jeff Bagby's sealed Tempest. I think it's 10.75" deep with the outer baffle.


Looks great then.
post #6455 of 9857
Quote:
Originally Posted by noah katz View Post

How about a sealed option?
Will add it.
post #6456 of 9857
Quote:
Originally Posted by smokarz View Post

Sounds like a really good idea. What's the volume on that box?

If that is the 26" high x 10.75" box that I have the interior volume is 1.57 CF minus the bracing, driver, wave guide, CD and ports. I did not want to see the brace , when looking into the slot port, so I reworked the bracing to hit on top of my slot port.
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post #6457 of 9857
That box is only 21" tall.
post #6458 of 9857
Whew! I just read this entire thread, beginning to end. Yep, every single post. It has taken me several weeks, maybe more like a month. I wish I would have caught wind of this a year or so ago and been able to help along the way. It's amazing what everybody here has accomplished. And Eric's efforts in particular are way over the top. Bravo!

Anyway, after reading about 6500 posts, I thought it was time I add one myself and make the task one post more daunting for the next guy trying to do the same tying. I'll be following this thread from here on. Now it's time for me to go create an account on DIYSG and start learning about specific designs. I've got to figure out which ones I'm going to build myself!
post #6459 of 9857
Quote:
Originally Posted by Erich H View Post

What about 2 slot ports separated by about 1"?
...
I'm just taking a wild guess, but maybe two 6" wide slot ports that are 1.15" tall versus one 13" wide slot port that's 1" tall? What do you think?

Erich, I really like those plastic slot ports! Even though I built my own boxes, I'd buy a flat kit for this to try out. I could measure it and post the response if we got the box size and tuning right for this driver. Let me know. cool.gif

With that box depth (10.75"), you couldn't really tune much lower than about 60Hz. Two 6" wide ports 1.15" high would be ~8.25" @ 60Hz. Plus, it would need to be taller than 21". Somewhere between 23-24.25" high to have the ports in front.

For 52Hz tuning F3 @ 80Hz, the ports would need to be 11.5" each. Lower tuning would require a slightly deeper box (double baffle would help with port length inside the box too, of course). I ran the 1.15 ft^3 box as 1 ft^3 after approximate driver and port displacement...this would need to be calculated more closely with the lower enclosure volume.
post #6460 of 9857
Quote:
Originally Posted by Erich H View Post

That box is only 21" tall.
Are you using that as an example or is that what you want to work with?
post #6461 of 9857
Quote:
Originally Posted by pgwalsh View Post

Are you using that as an example or is that what you want to work with?


No, that's just an example because I happen to have that picture. That's just the box for the 10" woofer designs.

Robotbunny, I'm really trying to find some bigger plastic slot ports, but I'm not having much luck right now. Those smaller ones are equal to a 1.9" diameter port, but they're only about 4.5" long or so. They're perfect for the 8" designs and 10" designs. But I'm not sure about any 12" models.
post #6462 of 9857
Quote:
Originally Posted by pitviper33 View Post

Whew!
Anyway, after reading about 6500 posts, I thought it was time I add one myself and make the task one post more daunting for the next guy trying to do the same tying. I'll be following this thread from here on.

biggrin.gifbiggrin.gif
post #6463 of 9857
Anyone have a spare pair of AE LO15s they're looking to sell? I could use a pair for a SEOS based project. smile.gif
post #6464 of 9857
Quote:
Originally Posted by Eternal Velocity View Post

tytte... you're making me want that seos-18 + Radian 951Be combo.... real bad

+1
post #6465 of 9857
I've only had 4 people put in for the TD12 baffles, which equates to 13 baffles. I know several people have already built their speakers, but is that it?

https://docs.google.com/spreadsheet/ccc?key=0Aq9nNVe5UHHbdDFjT2VrZHIyRVRRNjZKMHFRYlVXVUE#gid=0

https://docs.google.com/spreadsheet/viewform?formkey=dDFjT2VrZHIyRVRRNjZKMHFRYlVXVUE6MQ#gid=0
post #6466 of 9857
Quote:
Originally Posted by robotbunny View Post

Erich, I really like those plastic slot ports! Even though I built my own boxes, I'd buy a flat kit for this to try out. I could measure it and post the response if we got the box size and tuning right for this driver. Let me know. cool.gif
With that box depth (10.75"), you couldn't really tune much lower than about 60Hz. Two 6" wide ports 1.15" high would be ~8.25" @ 60Hz. Plus, it would need to be taller than 21". Somewhere between 23-24.25" high to have the ports in front.
For 52Hz tuning F3 @ 80Hz, the ports would need to be 11.5" each. Lower tuning would require a slightly deeper box (double baffle would help with port length inside the box too, of course). I ran the 1.15 ft^3 box as 1 ft^3 after approximate driver and port displacement...this would need to be calculated more closely with the lower enclosure volume.

look at a the 26" high x 14.5" wide x 10.75" deep box with double front baffle. You can tune that to around 52hz.
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post #6467 of 9857
Thanks Mike. Yeah, I saw those enclosures. With the enclosure depth even with double baffle, the plastic slot port would have to be both long enough and have the ability to bend at a prescribed length. With double baffle, we could go 55Hz, F3 78Hz with a 10" port length and still have enough space between the back wall and port mouth. Unfortunately, the plastic ports only come 4.5". If there was an extension tube for those slot ports that would be awesome!
post #6468 of 9857
Quote:
Originally Posted by robotbunny View Post

Thanks Mike. Yeah, I saw those enclosures. With the enclosure depth even with double baffle, the plastic slot port would have to be both long enough and have the ability to bend at a prescribed length. With double baffle, we could go 55Hz, F3 78Hz with a 10" port length and still have enough space between the back wall and port mouth. Unfortunately, the plastic ports only come 4.5". If there was an extension tube for those slot ports that would be awesome!

I have some 2.5" curved ports that only go back in the box 7" but give you a 10" port length. The ports are 3.5" outside flare diameter, and 2.5" inside. There's a small flare on the end as well.
post #6469 of 9857
Quote:
Originally Posted by Erich H View Post

I have some 2.5" curved ports that only go back in the box 7" but give you a 10" port length. The ports are 3.5" outside flare diameter, and 2.5" inside. There's a small flare on the end as well.

Is that a 2.5" plastic slot port tube? biggrin.gif
post #6470 of 9857
I'm working through different options for implementation of SEOS based mains, and I have a question for all the horn experts following this thread.

Ideally we'd place 90 degree horns like these at a 45 degree angle in the room, right? (Avoids early reflections, big sweet spot, all that.) Well what about flush mounting them inside some bass traps in the front corners of the room? I'm guessing you wouldn't realize the full benefit of corner bass reinforcement. Would being right up against both walls cause any HF reflection issues? The design is 6 dB down at 45 degrees, not 100 dB down. So some sound is going to be bouncing off those extremely close walls. Is that a problem?

One benefit I see is that it gives me a great way to hide my terrible wood finishing skills under the bass trap covering. Plus, instead of trying to convince my wife to allow "giant" new speakers AND 2 more bass traps, it'd visually only be 2 more bass traps and the elimination of 2 speakers! cool.gif

Thoughts?
post #6471 of 9857
Erich, any updates on the rest of the flatpacks for the SEOS kits? i know you were waiting on the CNC company for some stuff.
post #6472 of 9857
Quote:
Originally Posted by pitviper33 View Post

I'm working through different options for implementation of SEOS based mains, and I have a question for all the horn experts following this thread.
Ideally we'd place 90 degree horns like these at a 45 degree angle in the room, right? (Avoids early reflections, big sweet spot, all that.) Well what about flush mounting them inside some bass traps in the front corners of the room? I'm guessing you wouldn't realize the full benefit of corner bass reinforcement. Would being right up against both walls cause any HF reflection issues? The design is 6 dB down at 45 degrees, not 100 dB down. So some sound is going to be bouncing off those extremely close walls. Is that a problem?
One benefit I see is that it gives me a great way to hide my terrible wood finishing skills under the bass trap covering. Plus, instead of trying to convince my wife to allow "giant" new speakers AND 2 more bass traps, it'd visually only be 2 more bass traps and the elimination of 2 speakers! cool.gif
Thoughts?

Check out Wayne Parham's corner horns. http://www.pispeakers.com/CornerHorn.html Good technical discussion of how it works in there,

No clue what happens when you build them into or on bass traps.
post #6473 of 9857
Quote:
Originally Posted by Sibuna View Post

Erich, any updates on the rest of the flatpacks for the SEOS kits? i know you were waiting on the CNC company for some stuff.
http://www.avsforum.com/t/1379949/more-flat-pack-kits-coming/30
post #6474 of 9857
Thread Starter 
"Thoughts?"

it is a good idea. they don't have to be at exactly 45 degrees, but unless the room is quite long that would be a reasonable starting point.

http://www.cowanaudio.com/finale.html
post #6475 of 9857
Quote:
Originally Posted by pitviper33 View Post

Ideally we'd place 90 degree horns like these at a 45 degree angle in the room, right? (Avoids early reflections, big sweet spot, all that.) Well what about flush mounting them inside some bass traps in the front corners of the room? I'm guessing you wouldn't realize the full benefit of corner bass reinforcement. Would being right up against both walls cause any HF reflection issues? The design is 6 dB down at 45 degrees, not 100 dB down. So some sound is going to be bouncing off those extremely close walls. Is that a problem?

You're exactly right to notice that the sound from a 90° horn/waveguide is only 6dB down at 45°, not 100dB. Very good point, one that is missed by a lot of DIY newbies on the constant-directivity/waveguide scene. Very astute observation on your part.

That's why I think it's important that the waveguide chosen have pattern no wider than 90°, possibly even a smidge less. Definitely better to be in the 80°-90° range than the 90°-100° range.

But then again, that doesn't even matter much because we're only talking about a decibel difference at the "edge" of the horizontal coverage pattern. Still, we definitely don't want to be too wide.

We had this discussion earlier in the H290C waveguide thread.

One thing that should help ease your mind though - No matter whether your horizontal beamwidth is 80° or 90° or even 100° - the truth is the frequencies produced by the tweeter are high enough that absorbent room treatments are extremely effective at absorbing reflections, especially at the "grazing" angle they would be coming from in a constant directivity cornerhorn. Just put wedges along the walls adjacent to the speakers. At this frequency range, even drapes will do the trick.

This applies not only to constant directivity cornerhorns, but also to DI-matched two-way speakers placed a few feet from the walls. They are still close enough that reflections from the energy radiated outside the horizontal beamwidth are fairly significant.

Where you really have the most to worry about is in the midrange band, especially the lower midrange. As frequency drops, absorbent room treatments are less able to attenuate reflections. Still, the corners can be used to your advantage if you design the speaker to take advantage of them.


There's a lot more information on this and related subjects in the Pi Speakers FAQ. Most of the stuff in there relates to SEOS builds, as they use a very similar approach.

post #6476 of 9857

Another question about reflections... because we have to toe them in so much, is it a good idea to treat the front wall with something like Owens Corning 703?

post #6477 of 9857
Treatments like that are fine for HF absorption but ineffective at MF where you really need it. So absorbent material on the wall behind the speakers will help, but don't stop there. Consider taking these additional steps:

If you're running constant directivity cornerhorns, use a midhorn large enough to control the pattern at the upper end of its passband and close enough to the walls (within 1/4λ) for the walls to act as mouth extensions at the lower end of its passband.

If you're using DI-matched two-way speakers for mains, include helper woofers or flanking subs to mitigate midrange anomalies from reflections off the nearest boundaries.

post #6478 of 9857
Quote:
Originally Posted by Wayne Parham View Post
... absorbent room treatments are extremely effective at absorbing reflections, especially at the "grazing" angle they would be coming from in a constant directivity cornerhorn.

 

I vaguely recall in the acoustic treatments master thread localhost or SAC saying that at extreme angles of sound grazing the panel (20 degrees?) one would see less, not more absorption from panel absorbers? EDIT: At higher frequencies. One might think you'd get more effect, at a lower frequency, due to the increased thickness at that angle. But I guess the fabric isn't as acoustically-transparent at an angle as it is perpendicular, and so sound bounces more and absorbs less.

 

Or, I could just remember it wrong. confused.gif

post #6479 of 9857
Panel absorbers are most effective at low frequencies and very low midrange frequencies. They damp using sympathetic vibration of a panel and are tuned by panel size and compliance. Directivity isn't really an issue at these lower frequencies where the panel absorber is designed to work.

Fibrous materials like fiberglass, foam or cloth are used to absorb higher frequencies. They damp using sympathetic vibration of the fibers. The more fibrous material the sound goes through, the more attenuation there is. So the thickness of the damping material and the direction of the source (and the angle of incidence/reflection) are relevant for this kind of treatment because they have an effect on how much fibrous material the sound travels through.

So if we're talking about treatments to deal with early reflections from the tweeter, we're talking about fibrous materials. Things like the traditional foam wedges or cloth drapes. Those are sort of easy treatments, and will easily absorb early reflections from the tweeter.

If we're talking about reflections from the midwoofer, things are much harder to deal with. You either need panel absorbers or flanking subs. You really can't get a fibrous absorber thick enough to work at those frequencies.

But it's even better if you can run constant directivity cornerhorns, because they don't suffer reflections from the midwoofer. It is tucked back into the corner, well within 1/4λ from the nearest boundaries. That's why I only talked about fibrous treatments in the earlier post you were referring to about cornerhorns.

Of course, all speakers used indoors will benefit from distributed multisubs. This is a separate issue, mitigating room modes. But self-interference notches from nearest boundaries are a similar problem, one that can be dealt with using similar approaches.

The response fluxuations caused by room modes and self-interference both can be mitigated with dense interference from multiple sound sources blended together. That's what multisubs and flanking subs do. Cornerhorns just have a unique distinction of not creating self-interference notches in the lower midrange, so there's one less set of anomalies to mitigate.
post #6480 of 9857
Hi Wayne:
What placemetns do you recommend for the multisubs used in conjunction with corner horn in a simpel rectangular room (e.g. 16' x 23')? The other two corners?
Thanks.
Jack
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