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-   -   2" tapped or folded horn? (http://www.diyaudio.com/forums/subwoofers/178137-2-tapped-folded-horn.html)

bnbgn 29th November 2010 03:41 PM

2" tapped or folded horn?
 
This may be a silly question... but i'm really curious about this...
If one were going to get a 2" subwoofer to go down to it's absolute lowest... what would be the enclosure of choice? here's my speaker. http://www.amazon.com/Tang-Band-W2-1...pd_sim_sbs_e_5

it's rated to go down to 110 hz. If I build a halfwave folded horn for, say 40hz, so 1/2*28.1332 ~ 14'... will this configuration produce audible sound down to 40 hz? how about a quarter wave?, or is it just physically impossibly to get a 2" driver to resonate anything lower than 110 hz? If I knew it would work with 7' of horn i'd be happy...

I'm probably going about this wrong, because the way i understand it the surface size of your driver dictates your wavelength of interest... so if it's 110 hz.. i'm best going with a 1/2 of that? so 10.2303/2 or ~5 feet?

My second question is will a tapped horn or standard folded horn perform best for attempting to coax these low low's from such a small driver? If i knew how to run hornresp i'd try and plug the #'s in.

Thanks... just trying to generate some ideas..

bnbgnoise

Rademakers 29th November 2010 06:13 PM

You can bring this 2" 'monster' down to 40 Hz, though as a rule of thumb diving 2 times below Fs is the maximum. For a fixed enclosure volume going lower means less maximum output based upon excursion limits.

Reading this should give you the basic skills needed to design your horn: Guide to WinISD Pro and Hornresp - Speakerplans.com Forums - Page 1

Compression ratio could probably be between 1 to 6 or there abouts for starters.

Regards Johan

jbell 29th November 2010 06:38 PM

1 Attachment(s)
I guessed on Sd and Le, but here's a start...

Would be a fun little project made out of 1/8" bb ply as a computer sub sat in the corner of a room.

bnbgn 29th November 2010 06:54 PM

@Jbell thank you thank you! You feel my concept!? small, LOW. Thank you though, i will save that capture of those #'s as i know it will be usefull reference as I look into this. So you did, or didn't render the output for the horn resp... were you able to make any scene of the #'s as far as freq resp? Might I ask what the Sd and Le represent?

bnbgn 29th November 2010 07:34 PM

@rademakers Thank you Johan! Good to know it should be able to reach that low... I'll be more inclined to design it to have lower natural responses with a little less overall volume as I really want to see some mini-sub sub action. Thanks again!

jbell 29th November 2010 08:04 PM

Quote:

Originally Posted by bnbgn (Post 2381195)
@Jbell thank you thank you! You feel my concept!? small, LOW. Thank you though, i will save that capture of those #'s as i know it will be usefull reference as I look into this. So you did, or didn't render the output for the horn resp... were you able to make any scene of the #'s as far as freq resp? Might I ask what the Sd and Le represent?

I was kinda 'trying' to get you interested in downloading hornresp, entering the numbers and starting to play with it.

Sd is the area of the driver cone. 19cm2 is a full 2" and I know that with the surround, that that is optimistic. It's probably about 16cm2 at most. Le is the inductance of the driver coil, and is not specified, so I just guessed. There are great tutorials out there, and the online help for hornresp is good as well. David has done a HUGE service to anyone who wants to design/build.... the least I can do is encourage someone to pick it up, see how easy it is, and get a good idea of what is and isn't possible. My post was meant as a starting place.... not the end answer on what is possible with this driver.

bnbgn 29th November 2010 08:48 PM

That's awesome.. thank you for the starting #'s... that's a huge step forward... i've really wanted to learn horn resp... They should make a pictorial guide... or I should... (in a year when i figure it out) so it's easier to decypher... visual representations help me in understanding things alot better.

Thank you again!

jbell 29th November 2010 09:04 PM

1 Attachment(s)
Quote:

Originally Posted by bnbgn (Post 2381328)
That's awesome.. thank you for the starting #'s... that's a huge step forward... i've really wanted to learn horn resp... They should make a pictorial guide... or I should... (in a year when i figure it out) so it's easier to decypher... visual representations help me in understanding things alot better.

Thank you again!

nah... you should be up and running in less than an hour, not a year.... Here's a great hornresp tutorial by my friend mike... Simple Tapped Horn Tutorial using Hornresp - AVS Forum

And just as a teaser, to get you really interested in doing hornresp for your self. Here's the 10 watt output of your mighty little sub in a corner, 1 meter away. (typical for computer sub)

Now this keeps your driver under it's xmax rating from 60hz on up... You have said you wanted lower... time to play with hornresp and figure out how to make that happen.

bnbgn 29th November 2010 09:45 PM

Dang, Dude, Thank you... That is amazing software. very beutiful rendering of freq response, it's giving me hope! Now that I have my driver selected my cabinet parameters are the next step so there's no avoiding it now... what a cool tool.

If only I wern't being kicked out today I could clear the desk off and delve into it. So close, yet so far. Why my life plans change every day, i don't know, luckily I can continue research and design of my sub projects online. I should probably switch over to online flash-based cad design software too at this point and just live on the cloud.

Thank you so much jbell and others, bouncing ideas of experts is something i couldn't be more thankful to do!

18Hurts 29th November 2010 09:46 PM

Hey bnb,

I'll trade you a Bose AM-5 "bass module" for your 2" tapped horn. If you can get 2 octaves below Fs, it will go lower than the AM-5.

All kidding aside (although if you want to trade, I'll do it!) great to see a project rolling to make a mini-TH. I might make one to practice on a $20 driver and a half sheet of wood before tackling a dual 12" TH.


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