2 Drivers in one enclosure

mikealanlee · 21st February 2013, 12:25 AM

Hi All,

I know this question has been answered already but I'm having trouble finding a thread. Sorry for asking again. 3 questions:

1. 2 drivers in a passive radiator design, both in a single enclosure. Desired location for the 2 drivers is not symmetrical in the enclosure. Does this pose a problem? Or does driver location not matter. Bracing for enclosure will not be symmetrical either.

2. Same question for passive radiator location.

3. If there is an existing thread, can you point me in the right direction?

Thanks for putting up with this question again.

weltersys · 21st February 2013, 05:33 PM

Quote:

Originally Posted by mikealanlee

Hi All,

I know this question has been answered already but I'm having trouble finding a thread. Sorry for asking again. 3 questions:

1. 2 drivers in a passive radiator design, both in a single enclosure. Desired location for the 2 drivers is not symmetrical in the enclosure. Does this pose a problem? Or does driver location not matter. Bracing for enclosure will not be symmetrical either.

2. Same question for passive radiator location.

As long as the drivers and passive radiator are located within 1/4 wavelength of each other at the highest frequency of operation, location won't make a difference.

At 100 Hz, 1/4 wavelength is 2.8 feet, just under a meter.

mikealanlee · 21st February 2013, 05:44 PM

Weltersys,

That is great information! Thanks for sharing the knowledge.

Best Regards,
Mike

head_unit · 7th March 2013, 09:27 PM

Yeah, in theory it doesn't make a difference. In reality, there are probably differences, but very small.

One note, though: if the drivers are opposed i.e. mounted directly opposite and moving in-phase (that is, the the cones move away or towards each other at the same time), vibration can be reduced a lot.

Kindhornman · 7th March 2013, 09:47 PM

Head Unit,
I think that the reduction of vibration only holds if the two devices are physically linked, tied together from the magnetic structure or such. Two speakers on opposing sides that are not linked could in fact multiply the effect as the baffles would see double the loading from the two drivers.

weltersys · 9th March 2013, 06:19 PM

Quote:

Originally Posted by Kindhornman

Head Unit,
I think that the reduction of vibration only holds if the two devices are physically linked, tied together from the magnetic structure or such. Two speakers on opposing sides that are not linked could in fact multiply the effect as the baffles would see double the loading from the two drivers.

You are correct.
What Head Unit perhaps meant is that rocking motion of a large panel (or cabinet) can be reduced by opposed drivers.

As an example, large drivers with heavy cones will cause "wall flop" when mounted as an infinite baffle in a wall, while when mounted in a plenum, the plenum mounted to the wall, the wall will move little.

Same thing on a cabinet, the whole cabinet will tend to walk around with front mounted cones, but when the cabinet uses a plenum (which can be parallel walls or a "V" shape) the cabinet will remain stationary.

badman · 9th March 2013, 07:04 PM

Quote:

Originally Posted by Kindhornman

Head Unit,
I think that the reduction of vibration only holds if the two devices are physically linked, tied together from the magnetic structure or such. Two speakers on opposing sides that are not linked could in fact multiply the effect as the baffles would see double the loading from the two drivers.

The coupling from the box is enough for some force cancellation, IME- better still is to couple the drivers directly, but much of the force still cancels in a "normal" box, where the baffles are narrow relative to the driver diameter (1.5x or so). Wider baffles reduce this effect, but one can cross-couple the panels, and not the drivers, and achieve some of the same benefit.

Kindhornman · 9th March 2013, 07:25 PM

Welterssy and Badman,
I agree that there are multiple mechanisms at work here. Yes you can tie the structure together rather that the two devices and achieve basically the same effect. I have a friend who built some rather large PA enclosures and what he did in that application was to use a tension compression method of rods to tie the opposite sides together. What happens when you sometimes use just bracing to tie the two sides together is that the initial compression of the two sides is lost as the wood relaxes over time and hence his solution of tension/compression to keep the panels tied together. It was an interesting solution to a long term problem in a fixed installation.

21st February 2013, 12:25 AM	#1
mikealanlee diyAudio Member Join Date: Jan 2011	2 Drivers in one enclosure Hi All, I know this question has been answered already but I'm having trouble finding a thread. Sorry for asking again. 3 questions: 1. 2 drivers in a passive radiator design, both in a single enclosure. Desired location for the 2 drivers is not symmetrical in the enclosure. Does this pose a problem? Or does driver location not matter. Bracing for enclosure will not be symmetrical either. 2. Same question for passive radiator location. 3. If there is an existing thread, can you point me in the right direction? Thanks for putting up with this question again.

21st February 2013, 05:44 PM	#3
mikealanlee diyAudio Member Join Date: Jan 2011	Great Information Weltersys, That is great information! Thanks for sharing the knowledge. Best Regards, Mike

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
Two different drivers in same enclosure	Gaichuke	Multi-Way	32	3rd July 2009 06:31 PM
Help w/ drivers for an old enclosure	mjurban	Multi-Way	0	13th March 2009 12:42 AM
Best enclosure for these drivers?	SamV	Subwoofers	26	13th October 2008 05:30 PM
What Enclosure For These Drivers?	thetubeguy1954	Subwoofers	10	15th June 2008 05:19 PM
Multiple drivers in the same enclosure	MJ Dijkstra	Multi-Way	4	20th November 2006 10:01 PM

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

7th March 2013, 09:27 PM	#4
head_unit diyAudio Member Join Date: Feb 2004 Location: Los Angeles	Yeah, in theory it doesn't make a difference. In reality, there are probably differences, but very small. One note, though: if the drivers are opposed i.e. mounted directly opposite and moving in-phase (that is, the the cones move away or towards each other at the same time), vibration can be reduced a lot.

7th March 2013, 09:47 PM	#5
Kindhornman diyAudio Member Join Date: Aug 2012 Location: Los Angeles, California	Head Unit, I think that the reduction of vibration only holds if the two devices are physically linked, tied together from the magnetic structure or such. Two speakers on opposing sides that are not linked could in fact multiply the effect as the baffles would see double the loading from the two drivers.

9th March 2013, 07:25 PM	#8
Kindhornman diyAudio Member Join Date: Aug 2012 Location: Los Angeles, California	Welterssy and Badman, I agree that there are multiple mechanisms at work here. Yes you can tie the structure together rather that the two devices and achieve basically the same effect. I have a friend who built some rather large PA enclosures and what he did in that application was to use a tension compression method of rods to tie the opposite sides together. What happens when you sometimes use just bracing to tie the two sides together is that the initial compression of the two sides is lost as the wood relaxes over time and hence his solution of tension/compression to keep the panels tied together. It was an interesting solution to a long term problem in a fixed installation.