Need 8" sub - low Qts, low Fs???

geolemon · 16th June 2005, 04:55 PM

For an infinite-baffle type of install.

I believe an ideal IB sub has a low Qts (meaning low Qes really), and a low Fs, and I imagine a low Vas also... in layman's terms, a strong motor yet a low resonant frequency, and a stiff suspension.

And since our goal here is to increase the amount of output that an already installed "ho hum" 8 inch free air sub, one with a good amount of excursion capability too, I assume.

Any suggestions?
Thanks!

micb · 16th June 2005, 07:08 PM

Check out ImageDynamics ID8's.

I know plenty of people who have used then in IB installs to good result.

mike.e · 17th June 2005, 02:16 AM

IB = lots of displacement required.
Qts = Q system in IB meaning ,0.5-1.0 depending on bass 'taste'

Usually people use multiple 15"s with litres of displacement. Multiples of 8"s could do it.

simon5 · 17th June 2005, 03:05 AM

Cheap woofer

7 mm Xmax with 27 Hz Fs and a .37 Qts.

http://www.partsexpress.com/pe/showd...number=295-366

A bit more expensive and it's more like a 7 inch woofer.

13 mm Xmax with 30 Hz Fs and a .33 Qts

http://www.adireaudio.com/Home/ExtremisMidwoofers.htm

micb · 17th June 2005, 06:33 AM

Here are the details on the ID8's.

http://www.imagedynamicsusa.com/tech...type=sub&id=id

http://www.imagedynamicsusa.com/tech...type=sub&id=id

A pair is the minimum, 4 with 1000-1200 WRMS to the set is better if you want more output.

simon5 · 17th June 2005, 05:42 PM

^^ He found out better stuff, Image Dynamics is the way to go it seems.

theNoid · 18th June 2005, 01:29 AM

Quote:

Originally posted by geolemon
For an infinite-baffle type of install.

I believe an ideal IB sub has a low Qts (meaning low Qes really), and a low Fs, and I imagine a low Vas also... in layman's terms, a strong motor yet a low resonant frequency, and a stiff suspension.

And since our goal here is to increase the amount of output that an already installed "ho hum" 8 inch free air sub, one with a good amount of excursion capability too, I assume.

Any suggestions?
Thanks!

Is this for a car or home may I ask? I am hoping a car since you are considering only 8" drivers. As was mentioned, to achieve any kind of decent SPL levels, there is no replacement for displacement. When it comes to the Qts, I usually like lower to mid values better myself. But have heard plenty of great systems with drivers of high Qts specs as well.

For a neat looking little 8", check out http://www.soundsplinter.com and have a look at their...

Noidster

johninCR · 18th June 2005, 01:40 AM

For IB you want a mid Q driver because the system Q is the driver's Q as there is no "box" . A low Q drive will be over-damped and won't produce much bass in IB. Why would you want an 8" driver for an IB application anyway and except for under your desk or in a horn, I'd have a hard time calling something with an 8" driver a subwoofer ?

theNoid · 18th June 2005, 10:47 AM

Actually I have built several 8" based subwoofers that provided plenty of output into the low 30's and a few that provided useful output into the 20's as well. For an IB system though, unless we are talking about for a car here, I agree, 8" is not the way to go.

Noidster

johninCR · 18th June 2005, 03:44 PM

OK, I'll concede the point, but personally I'd still call them Subwoofer Jr's or bass augmenters.

16th June 2005, 04:55 PM	#1
geolemon diyAudio Member Join Date: Jan 2004 Location: Buffalo, NY	Need 8" sub - low Qts, low Fs??? For an infinite-baffle type of install. I believe an ideal IB sub has a low Qts (meaning low Qes really), and a low Fs, and I imagine a low Vas also... in layman's terms, a strong motor yet a low resonant frequency, and a stiff suspension. And since our goal here is to increase the amount of output that an already installed "ho hum" 8 inch free air sub, one with a good amount of excursion capability too, I assume. Any suggestions? Thanks!

17th June 2005, 03:05 AM	#4
simon5 diyAudio Member Join Date: Nov 2004 Location: Québec, Québec	Cheap woofer 7 mm Xmax with 27 Hz Fs and a .37 Qts. http://www.partsexpress.com/pe/showd...number=295-366 A bit more expensive and it's more like a 7 inch woofer. 13 mm Xmax with 30 Hz Fs and a .33 Qts http://www.adireaudio.com/Home/ExtremisMidwoofers.htm __________________ DIYaudio for President !

17th June 2005, 05:42 PM	#6
simon5 diyAudio Member Join Date: Nov 2004 Location: Québec, Québec	^^ He found out better stuff, Image Dynamics is the way to go it seems. __________________ DIYaudio for President !

18th June 2005, 01:40 AM	#8
johninCR diyAudio Member Join Date: Apr 2004 Location: Costa Rica	For IB you want a mid Q driver because the system Q is the driver's Q as there is no "box" . A low Q drive will be over-damped and won't produce much bass in IB. Why would you want an 8" driver for an IB application anyway and except for under your desk or in a horn, I'd have a hard time calling something with an 8" driver a subwoofer ? __________________ Everyone has a photographic memory. It's just that most are out of film.

18th June 2005, 10:47 AM	#9
theNoid diyAudio Member Join Date: Dec 2004 Location: Rock River, WY	Actually I have built several 8" based subwoofers that provided plenty of output into the low 30's and a few that provided useful output into the 20's as well. For an IB system though, unless we are talking about for a car here, I agree, 8" is not the way to go. Noidster __________________ "Mmmmm......Beeeer"


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16th June 2005, 07:08 PM	#2
micb diyAudio Member Join Date: Aug 2004 Location: UK	Check out ImageDynamics ID8's. I know plenty of people who have used then in IB installs to good result.

17th June 2005, 02:16 AM	#3
mike.e diyAudio Member Join Date: Sep 2004 Location: NZ	IB = lots of displacement required. Qts = Q system in IB meaning ,0.5-1.0 depending on bass 'taste' Usually people use multiple 15"s with litres of displacement. Multiples of 8"s could do it.

17th June 2005, 06:33 AM	#5
micb diyAudio Member Join Date: Aug 2004 Location: UK	Here are the details on the ID8's. http://www.imagedynamicsusa.com/tech...type=sub&id=id http://www.imagedynamicsusa.com/tech...type=sub&id=id A pair is the minimum, 4 with 1000-1200 WRMS to the set is better if you want more output.

18th June 2005, 03:44 PM	#10
johninCR diyAudio Member Join Date: Apr 2004 Location: Costa Rica	OK, I'll concede the point, but personally I'd still call them Subwoofer Jr's or bass augmenters. __________________ Everyone has a photographic memory. It's just that most are out of film.

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