4" Subwoofer?

akshayvaidya · 13th July 2006, 07:32 PM

Hi,

I have a couple 2.5W computer speakers and I thought it would be fun to try and build a miniature subwoofer for them. I have a 4" driver I'd like to use. Any ideas for the enclosure? I'd like it to be small and/or easy to construct.

I have a 7W amp chip that I'll combine with a filter and power supply to make the electronics, this I need to fit in the box too.

Thanks!
Akshay

zobsky · 13th July 2006, 08:01 PM

toss the 4", get an MCM 8" (can't remember the number offhead) and put it in a small box (maybe around 0.3 cu. ft. ported enclosure, . .play around in winisd) and it should serve well for PC duties,

7 watt might not be optimal for a SMALL subwoofer.

dangus · 14th July 2006, 05:17 AM

Most of the 4" drivers I've modelled are hard-pressed to go below 100 Hz, even in a ported box. Model it and see if there are any alignments that can get useful bass out of it. Maybe a bandpass box would give you some kind of thump.

lndm · 14th July 2006, 07:54 AM

I agree that the bandpass enclosure would allow the 4"er to put out low bass. You may need some power to get it loud.

An offbeat idea that may work for close quarters listening would be to use the 4" up to the baffle step frequency of the satellites. This may give a good bass tone to a set of computer speakers that happen to need it.

sreten · 14th July 2006, 02:33 PM

Hi,

without the parameters of the 4" driver box design is impossible.

/sreten.

Andy Westcott · 16th July 2006, 08:47 PM

How about horn loading it?
If you go for a cutoff of around 100Hz, it needn't be that big, especially if operating into 1/4 space or better.

The efficiency of this approach would also help overcome the power handling limitations of such a driver.

As you state this project is for fun, you needn't pay too much attention to correct horn flares, either. One of the good things about a horn is that even a really badly designed one will usually work to some degree!

Have fun!

paulspencer · 17th July 2006, 08:53 AM

Quite a stretch to get decent performance out of a 4" driver for bass. I'd consider a 5" midbass driver to be the minimum, and a 6.5" to be a good compromise of size and performance. Something like Vifa P17 in a vented box tuned from ~ 40 - 50 Hz. The 4" driver will have a lot of distortion, low output, and not much bass. If you do want to go ahead with it, you need some parameters to simulate its performance. Put it in a sealed box and you get no bass. Bandpass is tricky.

phase_accurate · 17th July 2006, 11:18 AM

There is even a "real" 6.5" sub driver available but it wouldn't come cheap:

http://www.monacor.de/int/en/prod_su...suche=raptor-6

Regards

Charles

RobWells · 22nd July 2006, 11:39 AM

Tangband also do a 4" subwoofer driver, and a few slightly bigger ones.

http://www.partsexpress.com/pe/pshow...number=264-824

Rob.

13th July 2006, 07:32 PM	#1
akshayvaidya diyAudio Member Join Date: Jul 2006	4" Subwoofer? Hi, I have a couple 2.5W computer speakers and I thought it would be fun to try and build a miniature subwoofer for them. I have a 4" driver I'd like to use. Any ideas for the enclosure? I'd like it to be small and/or easy to construct. I have a 7W amp chip that I'll combine with a filter and power supply to make the electronics, this I need to fit in the box too. Thanks! Akshay

13th July 2006, 08:01 PM	#2
zobsky diyAudio Member Join Date: Mar 2002 Location: Dallas, Tx, USA	toss the 4", get an MCM 8" (can't remember the number offhead) and put it in a small box (maybe around 0.3 cu. ft. ported enclosure, . .play around in winisd) and it should serve well for PC duties, 7 watt might not be optimal for a SMALL subwoofer. __________________ "Any fool can know. The point is to understand" - Albert Einstein

17th July 2006, 08:53 AM	#7
paulspencer diyAudio Member Join Date: Sep 2003 Location: Melbourne, Australia	Quite a stretch to get decent performance out of a 4" driver for bass. I'd consider a 5" midbass driver to be the minimum, and a 6.5" to be a good compromise of size and performance. Something like Vifa P17 in a vented box tuned from ~ 40 - 50 Hz. The 4" driver will have a lot of distortion, low output, and not much bass. If you do want to go ahead with it, you need some parameters to simulate its performance. Put it in a sealed box and you get no bass. Bandpass is tricky. __________________ AUDIO BLOG \| Bass integration guide My work: www.redspade.com.au web design studio

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14th July 2006, 05:17 AM	#3
dangus diyAudio Member Join Date: May 2004 Location: Vancouver Island	Most of the 4" drivers I've modelled are hard-pressed to go below 100 Hz, even in a ported box. Model it and see if there are any alignments that can get useful bass out of it. Maybe a bandpass box would give you some kind of thump.

14th July 2006, 07:54 AM	#4
lndm diyAudio Member Join Date: Mar 2006 Location: nsw	I agree that the bandpass enclosure would allow the 4"er to put out low bass. You may need some power to get it loud. An offbeat idea that may work for close quarters listening would be to use the 4" up to the baffle step frequency of the satellites. This may give a good bass tone to a set of computer speakers that happen to need it.

14th July 2006, 02:33 PM	#5
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, without the parameters of the 4" driver box design is impossible. /sreten.

16th July 2006, 08:47 PM	#6
Andy Westcott diyAudio Member Join Date: May 2006 Location: Exeter, England, UK	How about horn loading it? If you go for a cutoff of around 100Hz, it needn't be that big, especially if operating into 1/4 space or better. The efficiency of this approach would also help overcome the power handling limitations of such a driver. As you state this project is for fun, you needn't pay too much attention to correct horn flares, either. One of the good things about a horn is that even a really badly designed one will usually work to some degree! Have fun!

17th July 2006, 11:18 AM	#8
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	There is even a "real" 6.5" sub driver available but it wouldn't come cheap: http://www.monacor.de/int/en/prod_su...suche=raptor-6 Regards Charles

22nd July 2006, 11:39 AM	#9
RobWells diyAudio Member Join Date: Aug 2002 Location: UK	Tangband also do a 4" subwoofer driver, and a few slightly bigger ones. http://www.partsexpress.com/pe/pshow...number=264-824 Rob.

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