Help me balance SQ and SPL and weight for my sub - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 23rd February 2007, 05:09 PM   #1
diyAudio Member
Join Date: Jul 2003
Location: maryland, USA
Send a message via AIM to eRiCdWoNg
Default Help me balance SQ and SPL and weight for my sub

Ahh I havent been here in a while but I've got an itch to build a higher quality car subwoofer. I figure I'll put this in here rather then the car forum since more DIY enthusiasts frequent here.

Last night I tuned my car with my Velodyne SMS-1's analyzer (that I usually use in my home system). Put a display monitor on my hood and analyzed away. I adjusted the phase and EQ settings on my AudioControl crossover to optimize the sound.

I currently use a commercially made 15" car sub (of decent quality but its stamped steel) in a 1.75 cubic foot sealed sonotube in the back of my car. As expected there is the typical car audio bump from 35-65 Hz. After the phase correction and EQing it sounds pretty good, however it only plays to about 33 Hz before it rolls off. i pushed the 25 Hz EQ a bit to get a little more extension but still its dissapointing. In a car it should be easy to get to 15 Hz.

Sooooo.... I'm looking for some suggestions:
I require:
-High quality sound AND ability to get somewhat loud
-Ability to play flat to 20 Hz in a sealed enclosure in a car with minimal EQ "push"
-12" or 15" (or in between) preferably 15"
-4 ohm, single or dual 4 ohm voice coil (no 8 ohm SVC's)
-high power handling
-Light weight
-Passive radiator or sealed chamber (no bandpass or ported)
- not to be ridiculously expensive
-work in a 1.5-2.5 cubic foot enclosure

I looked at Parts Express they have some Dayton drivers that look appealing, though the beefier ones are too heavy.

Madisound recommended the following drivers to me:
1) 15" Aura Sound.
Its too expensive and way too heavy so its out.

2) Peerless XXLS 12" with 12" Passive radiator

3) Scan Speak 10"

High quality indeed, but from the specs and power handling it isn't gonna get too loud.

I know this is a difficult preposition but right now I'm liking the Peerless 12 + passive combination right now. I'm all ears!

  Reply With Quote
Old 23rd February 2007, 06:11 PM   #2
owdi is offline owdi  United States
diyAudio Member
owdi's Avatar
Join Date: Sep 2003
Location: Bellevue, WA
1.5 cu ft. is really small for a 15" sub. If you want response down to 15hz you will need to build a low Q sealed sub. Something less than .65 should be good.

For car audio I like to use two drivers, pointed away from each other. This will greatly reduce mechanical vibration without requiring a very heavy enclosure. Since you have only 1.5 - 2.5 cu. ft. to work with, you would have to use two 10" drivers. Anything bigger will not give you the low Q you need.

It sounds like your budget is around $300. How about a pair of Peerless 10" XLS drivers in 2 cu ft?

  Reply With Quote
Old 23rd February 2007, 07:31 PM   #3
diyAudio Member
Join Date: Jul 2003
Location: maryland, USA
Send a message via AIM to eRiCdWoNg
Thanks for that reply. This is pointing me in the right direction. I looked at the Peerless driver, looks pretty good.

I remeasured my enclosure, it is actually 2.2 cubic foot. I'm starting to like the 2 10" idea. I'm going to crunch some numbers, I'm also considering 2 of the previous-mentioned Scan-Speak woofers.
  Reply With Quote
Old 23rd February 2007, 08:28 PM   #4
beerman is offline beerman  United States
diyAudio Member
Join Date: Feb 2007
Location: Nebraska
Don't forget about cabin gain.

Design a sealed enclosure's F3 to fall within the cabin gain range and you're set. That's not difficult with most 15s.

WinISD's forum has a thread detailing to model it with the Linkwitz transform function in the WinISD Pro software (free alpha release download), though a few graphs are null and void.
Got Bass?
  Reply With Quote
Old 23rd February 2007, 08:39 PM   #5
diyAudio Member
Join Date: Jul 2003
Location: maryland, USA
Send a message via AIM to eRiCdWoNg
Right, this is going into the back of a C5 Corvette coupe. I have the luxury that the woofer is actually in the same airspace as me (rather then in a trunk, for example). I'm not sure what the cabin gain is. The car is relatively sensitive to weight in the rear, so I'm trying to keep it as light as possible.

I use BassBox Pro and it does have transform function modeling, however like any software generated "theoretical calculations" it isn't always accurate. I calculated solid performance to 17 Hz with my current setup, but its obviously way off the mark It also does not do passive radiators.

I may order the Peerless 12" with Passive Radiator. I've never played with a passive setup before and think it will be a sweet sounding rig without too much work.
  Reply With Quote
Old 24th February 2007, 08:32 PM   #6
diyAudio Member
Join Date: Jul 2003
Location: maryland, USA
Send a message via AIM to eRiCdWoNg
Well I may have figured out why my current sub wasn't playing that low. The AudioControl 24XS crossover I'm using for bass/midbass has a preprogrammed 33 Hz, 18 db/oct high pass filter. WAY too high. Couple that with 15 Hz high pass on the Audiocontrol DQX low pass on the EQ unit and thats a major slope. I'm going to change the resistor values and hopefully reprogram it to 15 Hz and I'll report back. I'm having a hard time finding 360K-480K ohm resistors though
  Reply With Quote
Old 25th February 2007, 01:39 AM   #7
diyAudio Member
Join Date: Jul 2003
Location: maryland, USA
Send a message via AIM to eRiCdWoNg
YUP! That's what it was. Turns out the local Radio Shack had 470K ohm resistors. Though they were 1/2 watt and 5% carbon. They will do for now. They were physically a bit large to fit in the slots so I had to pursuade them to go in. After I put them in the subwoofer definately plays lower, both to ear and to RTA. Woo hoo!

I will now order 1/4 watt metal film 1% resistors.
  Reply With Quote


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
How much weight does ABX carry? Wellfed Everything Else 24 19th September 2004 05:17 PM
A weight vs. linear weight gary f Multi-Way 1 2nd April 2004 01:23 PM
mdf weight jeffm Multi-Way 6 21st November 2002 10:18 PM

New To Site? Need Help?

All times are GMT. The time now is 06:07 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2