~50 lb tapped horn, woofer under $100, high efficiency, low power? - Page 3 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th August 2012, 02:27 AM   #21
diyAudio Member
 
Join Date: Nov 2007
Quote:
Originally Posted by turbodawg View Post
Or have I missed something?
You have missed something

Even of you achieve the same F3 and efficiency with a vented alignment compared to a TH or other 1/4 wave-based design with the same driver, what those SMALL-SIGNAL based models are not telling you is what happens to that response curve when you start applying more power to your vented alignment. With a vented alignment, you can expect compression at lower frequencies to affect the response, unless you make the vents VERY large. You won't or shouldn't run into this problem with a TH.
__________________
www.diysubwoofers.org
  Reply With Quote
Old 30th August 2012, 08:07 PM   #22
diyAudio Member
 
Join Date: Feb 2004
Quote:
Originally Posted by Brian Steele View Post
You have missed something

Even of you achieve the same F3 and efficiency with a vented alignment compared to a TH or other 1/4 wave-based design with the same driver, what those SMALL-SIGNAL based models are not telling you is what happens to that response curve when you start applying more power to your vented alignment. With a vented alignment, you can expect compression at lower frequencies to affect the response, unless you make the vents VERY large. You won't or shouldn't run into this problem with a TH.
I'm modeling with a pair of 4" round vents, that's more than enough for a low excursion 12" tuned to around 40hz. I don't think port compression will be an issue.
  Reply With Quote
Old 30th August 2012, 08:48 PM   #23
diyAudio Member
 
Join Date: Nov 2007
Hmm... My vented spreadsheet says that a 2512 in about a 56 liter box tuned to 41 Hz will give an F3 around 39 Hz. Sensitivity will be about 94.6 Hz

HornResp says that if I put that driver in a 110.6 liter (net) tapped horn with a resonance frequency around 35.75 Hz, it will get down to 36.75 Hz. Sensitivity will be 98 Hz, or 3.4 dB more sensitive than the vented alignment.

So, the TH works out to be over 3dB more sensitive than the vented alignment, and goes a bit lower too, the tradeoff being the larger box requirement.
__________________
www.diysubwoofers.org
  Reply With Quote
Old 30th August 2012, 10:23 PM   #24
diyAudio Member
 
Join Date: Feb 2004
Quote:
Originally Posted by Brian Steele View Post
Hmm... My vented spreadsheet says that a 2512 in about a 56 liter box tuned to 41 Hz will give an F3 around 39 Hz. Sensitivity will be about 94.6 Hz

HornResp says that if I put that driver in a 110.6 liter (net) tapped horn with a resonance frequency around 35.75 Hz, it will get down to 36.75 Hz. Sensitivity will be 98 Hz, or 3.4 dB more sensitive than the vented alignment.

So, the TH works out to be over 3dB more sensitive than the vented alignment, and goes a bit lower too, the tradeoff being the larger box requirement.
Right. Twice as big. How's the tapped horn doing in 56L.........?
  Reply With Quote
Old 30th August 2012, 11:06 PM   #25
diyAudio Member
 
Join Date: Nov 2007
Quote:
Originally Posted by turbodawg View Post
Right. Twice as big. How's the tapped horn doing in 56L.........?
Good luck trying to fit a 40 Hz TH for a 12" driver into an enclosure that small. Even if the HornResp predictions look decent, folding a TH into a volume that small with enough space to fit the driver will be near impossible.

With THs, the emphasis is on finding the best combination of efficiency and low frequency capability, not on minimizing box size. If your main concern is box size, then it's best to stick to one of the simpler sealed or vented alignments.
__________________
www.diysubwoofers.org
  Reply With Quote
Old 30th August 2012, 11:28 PM   #26
diyAudio Member
 
Join Date: Nov 2007
.. but I like a challenge, so

S1=S2=S3=S4 = 270 cm^2
L12=20 cm
L23=168.4 cm
L34=22cm

Gives response down to 40 Hz, sensitivity just over 96dB/2.83V/1M

Net volume works out to just over 57 liters

Good luck translating those parameters into an actual box though, particularly one that can hold a 12" driver.
__________________
www.diysubwoofers.org
  Reply With Quote
Old 30th August 2012, 11:34 PM   #27
diyAudio Member
 
Join Date: Feb 2004
Quote:
Originally Posted by Brian Steele View Post
.. but I like a challenge, so

S1=S2=S3=S4 = 270 cm^2
L12=20 cm
L23=168.4 cm
L34=22cm

Gives response down to 40 Hz, sensitivity just over 96dB/2.83V/1M

Net volume works out to just over 57 liters

Good luck translating those parameters into an actual box though, particularly one that can hold a 12" driver.
That's pretty similar to what I came up with for a TQWT for the 12" eminator, which turned out to be the same as a the vented box. But I had a ~400cm2 area, which seemed like it would work in a simple fold, roughly 20x20x15 overall.
  Reply With Quote
Old 31st August 2012, 12:06 AM   #28
diyAudio Member
 
Join Date: Nov 2007
Quote:
Originally Posted by turbodawg View Post
That's pretty similar to what I came up with for a TQWT for the 12" eminator, which turned out to be the same as a the vented box. But I had a ~400cm2 area, which seemed like it would work in a simple fold, roughly 20x20x15 overall.
That sounds kind of weird for a TQWT. Mouth size usually decreases as you go from TH->TP->TQWT. What are the rest of the HornResp parameters in your model?

Trying to shoe-horn the driver into the smallest 1/4L model though kinda negates some of the advantages of using this type of alignment. Do you know you can probably get down to 30 Hz at around 96dB/2.83V/1M with this driver? You'll need to use a 200L box though :-)
__________________
www.diysubwoofers.org
  Reply With Quote
Old 31st August 2012, 12:36 AM   #29
diyAudio Member
 
Join Date: Feb 2004
Here you go.....I adjusted my voltage to 2v for the nominal 1w on 4 ohms and get about 94 db. It was actually 360cm2 that I was working with, or 14x4". The s4 is reduced to compensate for the approximate cross section of the woofer at the mouth. A ported box of the same size sim's almost identical.
Attached Images
File Type: jpg TQWT.jpg (89.1 KB, 240 views)
File Type: jpg tqwt2.jpg (67.0 KB, 198 views)
  Reply With Quote
Old 31st August 2012, 02:04 AM   #30
diyAudio Member
 
Join Date: Nov 2007
Quote:
Originally Posted by turbodawg View Post
Here you go.....I adjusted my voltage to 2v for the nominal 1w on 4 ohms and get about 94 db.
Unless the program you're using for box modelling allows you to do the same adjustment for the vented alignment you're looking at, I suggest not doing this. Alternatively, use HornResp to model the vented alignment as well, so you can compare them directly in the same program.

Interesting idea though, putting in a "pinch" at S3 to reflect the effect of the driver on the cross-sectional area around there.


Quote:
Originally Posted by turbodawg View Post
It was actually 360cm2 that I was working with, or 14x4".
The mounting depth for the 2512 is 5.6", so that's not probably going to work out too well if you're planning to just bolt the driver to one side of the mouth. However, with 360 cm^2 available at S2, it might be possible to come up with a creative way of squeezing the driver in (e.g. magnet facing into S2, and mounting rings used at S3 to raise the driver up an inch or two so the magnet stands clear of the wall).
__________________
www.diysubwoofers.org
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cheap 10inch woofer in tapped horn? what would you do? ThyDntWntMusic Subwoofers 77 29th December 2011 11:38 PM
@ 20% 1/2 $100.00 give me 4 driver for tapped horn kornnylike Subwoofers 0 5th July 2011 08:58 PM
horn-loading: 100% efficiency ?! e-side Multi-Way 54 1st August 2006 02:42 PM
Low wattage, high efficiency, high quality? Nordic Multi-Way 5 4th September 2005 11:12 PM
efficiency of high power toroids at low load? capslock Parts 8 24th April 2002 10:26 PM


New To Site? Need Help?

All times are GMT. The time now is 01:02 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2