Question About Sealed Enclosures

MIW245 · 20th May 2009, 07:47 PM

Hi all,

Im fairly new to this so please go easy on me!

I have found some 5.5" drive units i would like to use in a loudspeaker. I am currently designing the speaker cabinet. The spec of the drive units says it needs an 11 litre sealed cabinet for optimum proformance. My question is, if i want to use 2 of these drive units in the same speaker, would i need to double the enclosure size to 22 litres, or would one 11 litre enclosure be sufficent for both drive units?

Thanks in advance!

M

planet10 · 20th May 2009, 08:03 PM

You need to double the volume.

dave

Moondog55 · 20th May 2009, 08:06 PM

Just double the volume for 2 drivers, but the bigger box may have more flex so will probably need a little more attention to bracing, so don't forget to subtract the volume of the bracing.
I generally just use a nominal 10 percent as the bracing volume and add that to the box volume first.

so 11 * 2 + 10% = 24.2litres. Just call it 25 and it is close enough as the drivers themselves need to be accounted for.

MIW245 · 20th May 2009, 09:01 PM

Many thanks for your responses, it helps a great deal talking to people with experiance.

Just so i can confirm, i am thinking about using two of these bass/mid drivers in each loudspeaker:

http://www.mcmelectronics.com/product/55-1205

With one of these tweeters in each loudspeaker:

http://cpc.farnell.com/_/dt-28n/neod...are/dp/LS01262

What cabinet type/size would you be tempted to use?

I'd like to add this is my first prodject and i know it won't be the best pair of speakers ever made, but hopefully it will give me a good bit of experiance for future prodjects

Moondog55 · 20th May 2009, 09:17 PM

The short answer is that I would not use them as a mid-woofer, even in a 50 liter box; the performance is poor with nothing below 150 Hz and power handling is modeling poorly, X-max is exceeded below 120Hz with 2 watts in a 25 liter sealed box.
As a cheap midrange they look good though.
Even though the Vas is low at 11 liters the high "Q" will give a peaky performance in a small sealed box, look for a driver with a "Qts" of about 0.42/0.55

Thawach · 20th May 2009, 09:30 PM

MIW245, look for a new mid-bass with qts around 0.35-0.4 fs is around 40-50 hz. can install with vented box likes my pic.

Thawach · 20th May 2009, 09:34 PM

Quote:

so 11 * 2 + 10% = 24.2litres. Just call it 25 and it is close enough as the drivers themselves need to be accounted for.

Moondog55 its easy if u can calculus by this link.

http://www.hometheatershack.com/foru...me-calculator/

Moondog55 · 20th May 2009, 10:03 PM

Thawatch; thanx for the link, nice box BTW!

PeteMcK · 20th May 2009, 10:30 PM

download WINISD Pro (free!!!) -
this program will let you see what a given driver can do before you part with any hard earned...
http://www.linearteam.dk/

Moondog55 · 20th May 2009, 11:06 PM

Or this one by Jeff Bagby

http://www.audio.claub.net/software/jbagby.html
follow links and download

20th May 2009, 07:47 PM	#1
MIW245 diyAudio Member Join Date: May 2009	Question About Sealed Enclosures Hi all, Im fairly new to this so please go easy on me! I have found some 5.5" drive units i would like to use in a loudspeaker. I am currently designing the speaker cabinet. The spec of the drive units says it needs an 11 litre sealed cabinet for optimum proformance. My question is, if i want to use 2 of these drive units in the same speaker, would i need to double the enclosure size to 22 litres, or would one 11 litre enclosure be sufficent for both drive units? Thanks in advance! M

20th May 2009, 08:03 PM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	You need to double the volume. dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

20th May 2009, 08:06 PM	#3
Moondog55 diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	Just double the volume for 2 drivers, but the bigger box may have more flex so will probably need a little more attention to bracing, so don't forget to subtract the volume of the bracing. I generally just use a nominal 10 percent as the bracing volume and add that to the box volume first. so 11 * 2 + 10% = 24.2litres. Just call it 25 and it is close enough as the drivers themselves need to be accounted for. __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

20th May 2009, 09:17 PM	#5
Moondog55 diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	The short answer is that I would not use them as a mid-woofer, even in a 50 liter box; the performance is poor with nothing below 150 Hz and power handling is modeling poorly, X-max is exceeded below 120Hz with 2 watts in a 25 liter sealed box. As a cheap midrange they look good though. Even though the Vas is low at 11 liters the high "Q" will give a peaky performance in a small sealed box, look for a driver with a "Qts" of about 0.42/0.55 __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

20th May 2009, 10:03 PM	#8
Moondog55 diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	Thawatch; thanx for the link, nice box BTW! __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"


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20th May 2009, 09:01 PM	#4
MIW245 diyAudio Member Join Date: May 2009	Many thanks for your responses, it helps a great deal talking to people with experiance. Just so i can confirm, i am thinking about using two of these bass/mid drivers in each loudspeaker: http://www.mcmelectronics.com/product/55-1205 With one of these tweeters in each loudspeaker: http://cpc.farnell.com/_/dt-28n/neod...are/dp/LS01262 What cabinet type/size would you be tempted to use? I'd like to add this is my first prodject and i know it won't be the best pair of speakers ever made, but hopefully it will give me a good bit of experiance for future prodjects

20th May 2009, 10:30 PM	#9
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	download WINISD Pro (free!!!) - this program will let you see what a given driver can do before you part with any hard earned... http://www.linearteam.dk/ __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky

20th May 2009, 11:06 PM	#10
Moondog55 diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	Or this one by Jeff Bagby http://www.audio.claub.net/software/jbagby.html follow links and download __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

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