BR vent and walls......

jay1st · 26th January 2008, 07:11 PM

This may sound stupid,

But for speakers which are supposed to be very close to a wall, is it better to have the BR vent on the front of the speaker's cabinet ?

And does it change the response moving it from the back to the front ?

Tnx......

Svante · 26th January 2008, 07:58 PM

The short answer is that it does not matter.

There are a few things to think about though.

If monted on the back, there has to be enough free space between the box and the wall, otherwise, the tuning will be slightly lowered if it is too close to the wall.

If monted on the front, close to the driver, pipe resonances in the tube will appear stronger due to the closeness.

There are other even smaller differences too.

jay1st · 26th January 2008, 08:04 PM

OK, tnx for the reply.

I guess the best is to experiment.
So I'll build 2 different cabinets and "hear" how different they sound and keep the one the suits me best.

Btw, what do you mean by "
the tuning will be slightly lowered if it is too close to the wall " ?
The frequency will get lower ?

Svante · 26th January 2008, 09:16 PM

Quote:

Originally posted by jay1st
Btw, what do you mean by "
the tuning will be slightly lowered if it is too close to the wall " ?
The frequency will get lower ?

Yes, the tuning frequency will be lowered if the passage on the back side is narrow. It is somewhat like lengthening the tube. But unless the box is really close to the wall, the change is small.

jay1st · 26th January 2008, 09:23 PM

Ok and tnx a lot.

nordhaven · 27th January 2008, 02:04 AM

Along this same line of thought could a pair of small bookshelf speakers be ported out the bottom to give a little lower freq? Like if feet were incorporated into the box design lifting the bottom of the box 1.5 to 2" from whatever the speaker was sitting on?

I found these super cool oak carved feet like the eagle talons and lions paws on balls you see on older hutches and furniture. I thought it would be fun to put these on a small bookshelf size speaker with some tiny crown molding on the edges for a classic look.

ente · 27th January 2008, 10:01 AM

... just to give an idea about the effects here a small experiment with a laser and STEPS from the ARTA family.

You see the DISPLACEMENT of the membrane. The dip is the tuning frequency of the box.

Some additional data:
- diameter of the port = 5 cm
- Size of box 45 x 26 cm

red = 1m, blue = 9 cm, green = 4 cm, black = 2,5 cm from backwall

Regards
Heinrich

PS: new ARTA release at the beginning of march

Svante · 27th January 2008, 06:22 PM

Quote:

Originally posted by ente
... just to give an idea about the effects here a small experiment with a laser and STEPS from the ARTA family.

Cool!

jay1st · 27th January 2008, 08:40 PM

That is way cool, thank you !

So, to be short, getting to close to a wall will modify the low end frequency response on the loudspeaker by increasing it's ability to go lower.

I guess it's one of those cheap tricks to make a small speaker go lower ?

26th January 2008, 07:11 PM	#1
jay1st diyAudio Member Join Date: Jan 2008	BR vent and walls...... This may sound stupid, But for speakers which are supposed to be very close to a wall, is it better to have the BR vent on the front of the speaker's cabinet ? And does it change the response moving it from the back to the front ? Tnx......

26th January 2008, 07:58 PM	#2
Svante diyAudio Member Join Date: Feb 2004 Location: Stockholm	The short answer is that it does not matter. There are a few things to think about though. If monted on the back, there has to be enough free space between the box and the wall, otherwise, the tuning will be slightly lowered if it is too close to the wall. If monted on the front, close to the driver, pipe resonances in the tube will appear stronger due to the closeness. There are other even smaller differences too. __________________ Simulate loudspeakers: Basta! Simulate the baffle step: The Edge

27th January 2008, 10:01 AM	#7
ente diyAudio Member Join Date: Aug 2004 Location: NNW of Rome	tiny laser measurements ... just to give an idea about the effects here a small experiment with a laser and STEPS from the ARTA family. You see the DISPLACEMENT of the membrane. The dip is the tuning frequency of the box. Some additional data: - diameter of the port = 5 cm - Size of box 45 x 26 cm red = 1m, blue = 9 cm, green = 4 cm, black = 2,5 cm from backwall Regards Heinrich PS: new ARTA release at the beginning of march

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pvc pipes for curved walls	polkymon	Multi-Way	13	26th October 2005 01:23 PM
different materials for bracing and walls?	morbo	Multi-Way	2	31st August 2005 01:22 AM
Method for attach fiberglass to MDF walls	JC Fardo	Multi-Way	7	13th April 2005 07:32 PM
5 inch walls?	amo	Multi-Way	27	13th January 2004 03:41 AM
non-parallel walls	sangram	Multi-Way	14	7th April 2003 08:13 AM


	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

26th January 2008, 08:04 PM	#3
jay1st diyAudio Member Join Date: Jan 2008	OK, tnx for the reply. I guess the best is to experiment. So I'll build 2 different cabinets and "hear" how different they sound and keep the one the suits me best. Btw, what do you mean by " the tuning will be slightly lowered if it is too close to the wall " ? The frequency will get lower ?

26th January 2008, 09:23 PM	#5
jay1st diyAudio Member Join Date: Jan 2008	Ok and tnx a lot.

27th January 2008, 02:04 AM	#6
nordhaven diyAudio Member Join Date: Jan 2008	Along this same line of thought could a pair of small bookshelf speakers be ported out the bottom to give a little lower freq? Like if feet were incorporated into the box design lifting the bottom of the box 1.5 to 2" from whatever the speaker was sitting on? I found these super cool oak carved feet like the eagle talons and lions paws on balls you see on older hutches and furniture. I thought it would be fun to put these on a small bookshelf size speaker with some tiny crown molding on the edges for a classic look.

27th January 2008, 08:40 PM	#9
jay1st diyAudio Member Join Date: Jan 2008	That is way cool, thank you ! So, to be short, getting to close to a wall will modify the low end frequency response on the loudspeaker by increasing it's ability to go lower. I guess it's one of those cheap tricks to make a small speaker go lower ?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read