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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: Mahendra Palesha on July 11, 2005, 10:08:05 am

Title: long throw subwoofer
Post by: Mahendra Palesha on July 11, 2005, 10:08:05 am
I want to build one subwoofer with 18" subwoofer for long throw application. I am thinking to build one of the style of the picture attached. The front & back both r with horns. Is this practical to do so? The suggestions & positive remarks welcome.
Title: Re: long throw subwoofer
Post by: Mac Kerr on July 11, 2005, 10:53:12 am
palesha wrote on Mon, 11 July 2005 10:08

I want to build one subwoofer with 18" subwoofer for long throw application. I am thinking to build one of the style of the picture attached. The front & back both r with horns. Is this practical to do so? The suggestions & positive remarks welcome.
If what your hoping to achieve is a subwoofer with directivity control, the way a horn would control the directivity of mids or highs, it ain't gonna happen. Horn loaded or front loaded, at sub frequencies a single box is omni directional. You can gain directivity by making an array of boxes. According to Dave Gunness of EAW a horn loaded sub with a large enough mouth area can simulate what we traditionally think of as long throw because there is a smaller gradient in SPL between a point close to the mouth and a point far from the mouth.

Mac
Title: Re: long throw subwoofer
Post by: Geri O'Neil on July 11, 2005, 08:09:47 pm
Mac Kerr wrote on Mon, 11 July 2005 09:53

palesha wrote on Mon, 11 July 2005 10:08

I want to build one subwoofer with 18" subwoofer for long throw application. I am thinking to build one of the style of the picture attached. The front & back both r with horns. Is this practical to do so? The suggestions & positive remarks welcome.
If what your hoping to achieve is a subwoofer with directivity control, the way a horn would control the directivity of mids or highs, it ain't gonna happen. Horn loaded or front loaded, at sub frequencies a single box is omni directional. You can gain directivity by making an array of boxes. According to Dave Gunness of EAW a horn loaded sub with a large enough mouth area can simulate what we traditionally think of as long throw because there is a smaller gradient in SPL between a point close to the mouth and a point far from the mouth.

Mac


Mac, I wonder if Dave Gunness would allow that post he did on this subject at the EAW forum to be posted around here somewhere. I've not read a more clearer expanation of why folks perceive horn-loaded sub cabinets to be long-throw. Should we ask him? Then we'd have to get it posted...hmm, that would be some doing now, wouldn't it... Mad

Geri O
Title: Re: long throw subwoofer
Post by: Gareth James on July 12, 2005, 05:53:29 am
I don't know where that designs from but i can't see it working too well. The rear path only looks a few inches longer than the front path, it would probably cancel at many frequencies.

If you're only planning on building one subwoofer you might be better simply building a standard sealed or vented enclosure.

As for long throw, if you built a big enough horn you might project the midbass a little further but then again if you're crossing it out at 80-100hz it won't mke any difference.

What is it for?

Gareth James
Title: Re: long throw subwoofer
Post by: Mahendra Palesha on July 12, 2005, 06:19:44 am
If i change the front to sealed or tuned port design, what will be the effects. My idea is to give maximum output at 80 hz. Looking at guidance from more experienced friends here.  
Title: Re: long throw subwoofer
Post by: John Halliburton on July 12, 2005, 07:41:24 am
My idea is to give maximum output at 80 hz...

That's just one design parameter.  It's possible to do this for any style of subwoofer discussed so far.  I think you need to ask yourself some other questions:

1.  What are your size limitations for a cabinet?

2.  How many cabinets are you planning to use at one time?

3.  How much talent do you have in cabinetmaking?  Building a horn
   loaded or bandpass cabinet takes quite a bit more effort than a
   vented design.

Finally, one comment about the thread so far, having maximum output at 80hz does not necessarily mean that you need a "long throw" design.  
Also, you need to be aware that designing something like this can lead to the classic "one note" subwoofer, known too as the "boom box" effect.  Other parameters and function can be degraded to a noticable point doing this.

Best regards,

John Halliburton
Title: Re: long throw subwoofer
Post by: Joe Jones on July 12, 2005, 08:16:50 am
Are you really looking for a subwoofer at all? You say you want maximum output at 80Hz, but that's where most subwoofers in large systems are being crossed over to the midbasses. I have my subs crossed to my mains at 80Hz. So I guess the rest of the question is where do you want to use the cabinet other than 80 Hz, higher or lower?
Title: Re: long throw subwoofer
Post by: Mahendra Palesha on July 12, 2005, 11:39:37 am
1. What are your size limitations for a cabinet?

Ans : Approx. 6~7 cu. ft.

2. How many cabinets are you planning to use at one time?
Ans: Minimum 2

3. How much talent do you have in cabinetmaking? Building a horn
loaded or bandpass cabinet takes quite a bit more effort than a
vented design.
4. My friend is a professional PA cabinet maker. That's why i can do it as i want.

Finally, one comment about the thread so far, having maximum output at 80hz does not necessarily mean that you need a "long throw" design.
Also, you need to be aware that designing something like this can lead to the classic "one note" subwoofer, known too as the "boom box" effect. Other parameters and function can be degraded to a noticable point doing this.

Ans: Yes, I agree with ur views,  but my frind likes this kind of bass. So he want me to design this for him.
Title: Re: long throw subwoofer
Post by: Mahendra Palesha on July 12, 2005, 11:48:46 am
Are you really looking for a subwoofer at all? You say you want maximum output at 80Hz, but that's where most subwoofers in large systems are being crossed over to the midbasses. I have my subs crossed to my mains at 80Hz. So I guess the rest of the question is where do you want to use the cabinet other than 80 Hz, higher or lower?
Ans : I will like to use 80hz. as a near center frequency with more towards higher side.
Title: Re: long throw subwoofer
Post by: Johan Rademakers on July 14, 2005, 11:00:40 am
Why do you want to use an 18" (and any 18" in particular perhaps)?

Your obviously looking for a kickbin, not a subwoofer. In that category most of the advantages that an 18" has to offer will be gone. So why not make a 15" kickbin instead? In which case the HD15 (or HD215) immediately comes to mind.

Mvg Johan
Title: Re: long throw subwoofer
Post by: Mahendra Palesha on July 14, 2005, 08:42:13 pm
Dear Johan,
Thank u very much for ur understanding perfectly. My friend has already bought 18" subwoofer. Hence i hv no choice but i will advice him about this.
Now tell me how to go ahead,
Palesha
Title: Re: long throw subwoofer
Post by: Graeme Goodacre [Centauri on July 15, 2005, 02:36:00 am
Maybe something like http://www.speakerstore.nl/index.php?l=en&pg=11&c=16 will work for you.

Cheers
Graeme
Title: Re: long throw subwoofer
Post by: Mahendra Palesha on July 15, 2005, 10:09:47 am
Thank u Graeme, I will try this.