12" driver enclosure size - 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 26th August 2010, 09:28 PM   #1
diyAudio Member
 
Join Date: May 2010
Location: Where the world's best tea come from:Kericho Kenya
Default 12" driver enclosure size

Hi guys,
I have a kenwood kfc w3010.I would like to design an enclosure.I have a few questions:
*Where is the boundary in terms of volume between tight bass and deep bass?
I like deep but not boomy.
*Stuffing material would be a layer of blanket,how would this affect the perceived volume?
I would like to go sealed though it compromises efficiency,but then the driver is quite efficient at 93 db/w/m.
What do you think?How large will a ported one need to be to go down to 25 Hz?
Regards.
__________________
if there are no sparks,it probably doesn't work!
  Reply With Quote
Old 27th August 2010, 10:40 PM   #2
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
A ~flat response in-room is required, so it's a function of the room's Q summed with the cab's Q, ergo there's no set volume that defines it. A speaker setting on a large parking lot (half space loading) OTOH will need a Qtc (sealed) or Qtb (vented) = 0.707 or what's commonly referred to as a T/S max flat alignment.

From this we see that a < 0.707 Qt alignment is usually required in-room to keep it from sounding 'boomy'.

What are the driver's specs?

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 27th August 2010, 11:51 PM   #3
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
Originally Posted by GM View Post
A ~flat response in-room is required, so it's a function of the room's Q summed with the cab's Q, ergo there's no set volume that defines it. A speaker setting on a large parking lot (half space loading) OTOH will need a Qtc (sealed) or Qtb (vented) = 0.707 or what's commonly referred to as a T/S max flat alignment.

From this we see that a < 0.707 Qt alignment is usually required in-room to keep it from sounding 'boomy'.

What are the driver's specs?

GM
Filling in...

b
Attached Images
File Type: jpg Kenwood-KFC3010.JPG (127.8 KB, 303 views)
File Type: jpg Kenwood-KFC3010_T-TQWT.JPG (584.7 KB, 295 views)
  Reply With Quote
Old 28th August 2010, 11:10 AM   #4
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Adding revised box calculations and a TH suggestion:

b
Attached Images
File Type: jpg Kenwood-KFC3010_TH.JPG (581.1 KB, 246 views)
  Reply With Quote
Old 29th August 2010, 03:36 AM   #5
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Quote:
Originally Posted by bjorno View Post
Filling in...
Thanks! As fate would have it, I Googled for it right after posting and found it immediately, but got sidetracked and all I got done was loading it into WinISD Pro which returned an 80.8 L net/28 Hz vented alignment with a 200 W peak handling to Fb. Even at this relatively low power it still needs dual 4" vents > 27" long, so as you know, some form of larger TL loading is required to make this driver 'sing'.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 30th August 2010, 12:34 PM   #6
diyAudio Member
 
Join Date: May 2010
Location: Where the world's best tea come from:Kericho Kenya
Thanks!I just installed WinISD Pro.I loaded the values but i seem to get totally different results.I've never used it before but i went through a tutorial step by step.
Let me describe it just after hitting the 'finish' button before any changes:
*80.35 litres
*Tuning freq 29.90 Hz
*4" dia 26.57 cm long port
*frequency response -3.033dB at 27.70 hz
0.006dB at 46.39 hz and peaks at 119.49 hz at 0.968dB before dropping.
I hope you get the picture.
My other concern is about the sensitivity,according to WinISD its 88.81dB/W/M but according to the datasheet its 93dB.Which is the real value?I thought sensitivity is a measured value rather than a calculated value?
How does a frequency response of boomy box look like?How about a 'tight bass' one?
What do you mean by 'TL loading'?
Regards.
__________________
if there are no sparks,it probably doesn't work!
  Reply With Quote
Old 30th August 2010, 02:25 PM   #7
diyAudio Member
 
Join Date: May 2010
Location: Where the world's best tea come from:Kericho Kenya
here:
Attached Images
File Type: jpg winisd2.JPG (92.8 KB, 168 views)
__________________
if there are no sparks,it probably doesn't work!
  Reply With Quote
Old 1st September 2010, 05:36 PM   #8
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
You're welcome!

The program returned an audibly insignificant alignment to mine, so at a glance it's a potentially viable design once damped. It chose too small a vent though due to it assuming a 1 W input, so in the SIGNAL tab, input 200 in the SYSTEM INPUT POWER window and check its REAR PORT-AIR VELOCITY plot with the understanding that you want it to be < ~17 m/s (and preferably lower) to keep it from audibly compressing and adjust the vent number/size as required to get predicted vent length. Note that it's a good plan to have all dims the same to avoid confusion (in, cm, etc.).

Its calculated sensitivity is a realistic one to design based on whereas a manufacturer's published measured one is often either a high inductance peak or break-up mode well above its intended pass-band, i.e. the audio industry's equivalent to the vehicle marketing horsepower 'race' of the '60s. Just like back then, 'when the flag drops, the B_S stops', so BW limit the driver to its nominally flat pass-band and its measured sensitivity in half space should be very close (if not spot on) to its calculated one.

'Boomy' (under-damped)/'tight' (over-damped) sounding in-room can be caused in various ways and more than likely the one you posted will sound 'boomy' in a typical HIFI/HT app if not damped even though it would be relatively 'tight' outdoors, but the obvious is to just either tune what you have a few Hz higher/lower to see this and why fine tuning a vented alignment in-room is so critical to overall good performance.

Transmission Line (TL) alignments encompass all 1/4 WL resonant pipe/horn layouts that don't have a well defined vent, so must be fine tuned with damping material for wide BW performance above its 3rd harmonic two octaves above its tuning (Fp), i.e. a 20 Hz Fp has a ~80 Hz 3rd harmonic dip and 'rippled' response above it.

Historically, an optimum TL alignment is stuffed until the driver's Fs impedance peak is ~completely flattened, ie. aperiodically loaded to present a ~matching impedance (DF = 1) to the low/power high output impedance amps of the day. Properly designed, it also flattens out the rest of the driver's response in its pass-band, so includes any mid bass hump in the response due to an excessively high voice coil (VC) inductance.

With the advent of ever increasing higher power and lower output impedance amps though, these alignments for the most part went the way of the Dodo bird and has only had a resurgence since MJK published his findings some years ago, then offering MathCad software to accurately design them and their mass loaded (vented) variants (MLTL, etc.).

Specifically to my remark though, today's mainstream drivers are designed to work in very acoustically small box volumes (Vb) with the trade-off being lower efficiency, so obviously more power is required to reach a given SPL which in turn means a larger, longer vent to keep vent compression low. At some point then, the vent becomes big enough in bulk that one might as well morph it with the box Vb to create a reverse tapered horn (TQWT) to increase loading/damping for a given bulk.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 20th September 2010, 10:08 AM   #9
diyAudio Member
 
Join Date: May 2010
Location: Where the world's best tea come from:Kericho Kenya
Hi guys
sorry i haven't replied,i've been busy with class work.
Anyway,i thought of updating you guys of the development. I ended up with a 99 litre box with a 4" inch diameter port tuned to 29hz. It sounds decent with a 40 watt amp,but the bass is not that deep as i expected.
I have another question:i've read about woofer break in,is it a fact? I already have a sine wave generator. How do i go about it?
Regards.
__________________
if there are no sparks,it probably doesn't work!
  Reply With Quote
Old 20th September 2010, 08:50 PM   #10
diyAudio Member
 
Join Date: Nov 2007
Quote:
Originally Posted by xeclipse View Post
Hi guys
sorry i haven't replied,i've been busy with class work.
Anyway,i thought of updating you guys of the development. I ended up with a 99 litre box with a 4" inch diameter port tuned to 29hz. It sounds decent with a 40 watt amp,but the bass is not that deep as i expected.
I have another question:i've read about woofer break in,is it a fact? I already have a sine wave generator. How do i go about it?
Regards.
I've yet to see any convincing data that supports "woofer break in". My own measurements do not support it.

I take it you used the published specs of your woofer. The actual specs might be quite different. Know anyone with a WT3? .
  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
Need 10" (12") driver for 30 ltr enclosure. (1.1 cu.ft) Fasen Subwoofers 2 25th March 2010 03:18 PM
Car sub enclosure for 12" driver juxta Subwoofers 8 25th March 2010 07:36 AM
For Free (local pickup only) : Sonotube enclosure for 12" driver zobsky Swap Meet 6 9th May 2007 06:19 PM
WTB ElectroVoice SP-12, 12" FR driver rcavictim Swap Meet 3 8th October 2004 06:33 AM
Enclosure size for Vifa M26WR 10" The Paulinator Multi-Way 7 21st December 2003 05:46 PM


New To Site? Need Help?

All times are GMT. The time now is 02:17 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