critical Q for car - 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 23rd October 2004, 06:17 AM   #1
diyAudio Member
 
Join Date: Jan 2004
Location: Greenville SC
Send a message via AIM to Chris8sirhC
Default critical Q for car

Ive read through the tread below and I was wondering how hard would it be to do a critical Q sub with two peerless XLS-12 subs if they are used in a car? Would it be that much harder to modify a car amp? I'm thinking I should just stick with sealed.

this thread
  Reply With Quote
Old 23rd October 2004, 09:35 AM   #2
diyAudio Member
 
RobWells's Avatar
 
Join Date: Aug 2002
Location: UK
I believe Peerless do a car version of the XLS so maybe that could be more appropriate ?

http://www.d-s-t.com/peerless/index.htm


Cheers,

Rob
  Reply With Quote
Old 25th October 2004, 08:21 AM   #3
mike.e is offline mike.e  New Zealand
diyAudio Member
 
mike.e's Avatar
 
Join Date: Sep 2004
Location: NZ
Send a message via ICQ to mike.e Send a message via MSN to mike.e
You could leave the car amp how it is-and adjust an active EQ circuit to make the frequency response how u want incar.
  Reply With Quote
Old 26th October 2004, 11:06 AM   #4
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
The car version has lower impedance which is appropriate for car amps. It's also slightly more expensive. It has a higher fs and is more efficient. All this translates into more output in a car - you don't need the fs as low as you get more assistance from the cabin gain. For cars, sealed makes sense as the rolloff should be quite close to the cabin gain. I believe the car version is also suited to an even smaller box.

With a vented box you have to make sure it doesn't get boomy due to cabin gain. Space is also a premium so a vented car box can be a lot more tricky since you try to tune fairly low to avoid boominess - probably more like an EBS. In such a small box its difficult to get a decent vent.

Now in a typical flashy looking car audio subwoofer, you don't have much xmax (despite their big surrounds they often have a wimpy 5mm xmax), so its not quite so difficult to get a vent in. But if you get a serious car audio sub like the XLS car version, then it's a bit more of a challenge.

I'd just go with a sealed box.

Have a look at diysubwoofers.org as they have some good info on car subs and cabin gain

Two great things about car subs:

1. no room modes (you are spared probably the biggest hassle with home audio subs)
2. small space means lots of bass with just a small sealed box

A critically damped alignment is a good thing, but infinite baffle is even better. If you can put a sub in a car so that it uses the boot as the box, then do it. If you are feeling clever you could use a second driver and push pull operate them. It means being a little tricky in how they are mounted. In some cases this would be an understatement.

If you must make a box then there are many tutorials on doing with with fibreglass to fit into your car.

Warning!!! - the XLS drivers have an impedance curve that dips low. Your amp must be stable down to 2 ohms for the 4 ohm car version.
  Reply With Quote
Old 27th October 2004, 08:13 AM   #5
diyAudio Member
 
BassAwdyO's Avatar
 
Join Date: Jun 2004
Location: Illinois
Send a message via AIM to BassAwdyO
Xls isnt too spectacular. For car audio get a car audio sub yes. Adire has some pretty good subs that are well priced to say the least. The Tempest and DPL12 are good subs with XBL2 and high Xmax. A DPL12 will have a low Q in even a small box so you can get relitively dampend bass without taking up much room for a big box. You can go ported if you'd like, but sealed does match the ~12db/octave rolloff of cabin gain pretty in most vehicles.
__________________
The golden rule of DIY:
Build nice, or build twice!
  Reply With Quote
Old 27th October 2004, 08:31 AM   #6
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
Quote:
Xls isnt too spectacular.
Quite a few, notably including Linkwitz, would disagree.

Quote:
The Tempest and DPL12 are good subs with XBL2 and high Xmax.
Don't you mean Tumult?

DPL12 with XBL2? Are you sure about that?!!!

DPL12 is designed contrary to the logic normally used for car subs - high fs and higher efficiency. Seems a questionable choice to me. The basket is a nice design if you intend for it to be seen though.
  Reply With Quote
Old 27th October 2004, 11:26 AM   #7
BAM is offline BAM
diyAudio Member
 
Join Date: Sep 2001
Location: Carmel, IN; West Lafayette, IN
Send a message via AIM to BAM
Neither of those drivers have XBL^2. Only the following drivers have XBL^2

Adire Koda 8, 10, 12 (15?)
Adire Extremis 6
Adire Sadhara 12
Adire Brahma Series (10, 12, 15, Extreme)
Adire Tumult
CSS SX10
CSS WR125
Resonant Engineering XXX Series

There are some others which aren't commercially available, and others that just aren't commercially available yet, and probably some that I've just plain missed, but the Tempest and the DPL2 still have regular SGLC motors.
  Reply With Quote
Old 28th October 2004, 05:25 AM   #8
diyAudio Member
 
BassAwdyO's Avatar
 
Join Date: Jun 2004
Location: Illinois
Send a message via AIM to BassAwdyO
uhh yeah, your right about the adire subs and xbl2. Apparently I should cut back on the crack smoking. I wouldnt say the XLS is anything spectacular still however. 12.5mm one way excursion, how low can you go? not very. One thing I think myself is that for true reproduction of the low freuquencys we need first, Low Fs. Second, high Xmax and Sd. Im not talking about anything above 40hz, even some midwoofers can go that low, especially in car. Subwoofers either need incredible xmax or incredible Sd. Both together will give you the most LF output. I dont like the idea of a dinky 12 with 12.5mm excursion, no matter how crisp it may sound. When I'm lookin for subs, its all about excursion, cuz thats what really matters for my infrasonic version of that sound. I'll comprimise a bit of SQ but if I can get down to 10hz its worth it. 10hz is easily achieved in car with cabin gain with some good subs and a proper enclosure (sealed preferrably for good music listening and little comprimise on LF extension)
__________________
The golden rule of DIY:
Build nice, or build twice!
  Reply With Quote
Old 28th October 2004, 09:45 AM   #9
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
Out of curiosity I did a comparison of the XLS-car vs home audio version vs the DPL, all in a 28L sealed box.

The XLS drivers had a low Q in a box this size, 0.6 for the car version & 0.5 for the home version. The DPL wants a bigger box and has a Q of 1 in a box this size. The transient performance is likely to suffer.

Looking at the response, both the XLS car and home audio version are very similar. In fact, it seems the real advantage of the car version is that it has a lower impedance, hence it will make better use of the amps power. The DPL has a slightly sharper rolloff which occurs lower.

Consider that cabin gain will typically be 12db/octave below 60 - 80 Hz. Below 50 Hz the XLS subs rolloff at about 8 - 9 dB/octave. The DPL rolls off below 35 Hz @ about 12db/octave. As a result, the DPL will have a big boost around 40 - 60 Hz. The XLS looks likely to be a better match with cabin gain IMO.

The tiny difference in xmax between the XLS vs the DPL of 1.8mm is nothing to speak of. It amounts to less than 1db!

Of course, if you really did want the DPL, then you can use eq, which is probably a good idea no matter what driver you chose. You change the Q with a Linkwitz transform, but I doubt this would be as good as using a driver that has a lower Q in a small box in the first place.

If the XLS doesn't have enough output for you, then there is always the Brahma!

Here's the chart, with gain applied so that the F3 of each can more easily be seen.

Red - XLS car
Green - XLS
Blue - DPL
Attached Images
File Type: gif dpl-blue vs xlscar-red vs xls-grn.gif (10.8 KB, 83 views)
  Reply With Quote
Old 28th October 2004, 09:47 AM   #10
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
For those who are interested:

Cabin gain measurements

DIY subwoofers.org comments on car audio subs
  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
The Critical Ear fauxpas Tubes / Valves 36 18th December 2007 05:16 PM
Clock cap value critical? tubenut Digital Source 2 23rd August 2005 03:10 PM
Rasmussen critical Q sub oblong Subwoofers 5 2nd May 2005 01:18 AM
Critical resistors Baard Tubes / Valves 5 28th March 2005 10:26 PM


New To Site? Need Help?

All times are GMT. The time now is 10:42 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