Benefits to woofer above tweeter?

cyberspyder · 3rd July 2008, 09:11 PM

I've seen a couple of plans that specify for the tweeter to be below the woofer....does it sound different from a more conventional tweeter above woofer?

cyberspyder · 4th July 2008, 08:54 PM

Comeon, almost a 100 views and not one answer?

MJL21193 · 4th July 2008, 08:59 PM

Hi,
It shouldn't matter, providing the drivers are close together.

augerpro · 4th July 2008, 09:26 PM

Typically it's done to compensate for lobing. The main lobe may point downwards so by flipping the drivers it will point upwards. Of course the actual tilt, driver height, and listening height all influence this decision.

Dave Bullet · 4th July 2008, 09:30 PM

Assuming a 2 driver 2 way - there are a few of reasons (and probably more):

1. tilt the primary vertical lobe upward, since the acoustic centre of the tweeter is further forward that the woofer. This would normally place the woofer on the listening axis. The same effect (tilting primary vertical lobe) can be achieved with asymetric crossover slopes

2. Position the woofer to minimise the 5th harmonic pipe resonance in very tall enclosures

3. Place the woofer appropriately in a desired transmission line

Essentially - driver orientation, as well as off centre baffle placement are merely different solutions to the same problems. With speaker building there are often (at least) a couple of solutions to each problem.

David.

rabbitz · 5th July 2008, 01:18 PM

Inverted drivers are at times used with odd order crossovers to compensate for the downward polar tilt caused by phase difference between the high and low pass sections.

If the geometry of the drivers are done correctly then you can get a +15° tilt from the drivers which compensates for the -15° tilt from the odd order filter. Result ZDP (zero delay plane) becomes 0°.... sort of a pseudo time alignment.

There's some info on it in the Loudspeaker Design Cookbook (7.23 in 6th edition).

tinitus · 5th July 2008, 03:04 PM

I know a skilled and VERY critical designer, who would never do that, but he actually ended up doing just that, so yes I suppose it can be done right ... as rabbitz points out, if you know what you are doing

forr · 5th July 2008, 11:01 PM

I suggest to play with Edge :
http://www.tolvan.com/
to observ the diffraction effects on a tweeter positionned on a more central position than usual.

Andy G · 5th July 2008, 11:30 PM

As Dave said, this type of design is often required in folded pipe designs , where the main driver needs to be at a specific position in relation to the pipe. This invariably (because of the way things need to be done) puts the woofer at the top the box, near the fold.

So it is generally the woofer position that forces this type of design.

That being said, so long as you watch the acoustic axis of the x-o, there should not be any problems.

tpsorin · 6th July 2008, 10:34 AM

One benefit, I can think of, is to have tweeter at ear level in case of very tall speaker, or in case that you listen from bed.

I don't think there are many other differences.

3rd July 2008, 09:11 PM	#1
cyberspyder diyAudio Member Join Date: Feb 2008	Benefits to woofer above tweeter? I've seen a couple of plans that specify for the tweeter to be below the woofer....does it sound different from a more conventional tweeter above woofer?

4th July 2008, 09:26 PM	#4
augerpro diyAudio Member Join Date: Aug 2006	Typically it's done to compensate for lobing. The main lobe may point downwards so by flipping the drivers it will point upwards. Of course the actual tilt, driver height, and listening height all influence this decision. __________________ ~Brandon DriverVault Soma Sonus Old Driver Tests

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4th July 2008, 08:54 PM	#2
cyberspyder diyAudio Member Join Date: Feb 2008	Comeon, almost a 100 views and not one answer?

4th July 2008, 08:59 PM	#3
MJL21193 Account disabled at member's request Join Date: Mar 2007	Hi, It shouldn't matter, providing the drivers are close together.

4th July 2008, 09:30 PM	#5
Dave Bullet diyAudio Member Join Date: Jan 2002 Location: Wellington, New Zealand	Assuming a 2 driver 2 way - there are a few of reasons (and probably more): 1. tilt the primary vertical lobe upward, since the acoustic centre of the tweeter is further forward that the woofer. This would normally place the woofer on the listening axis. The same effect (tilting primary vertical lobe) can be achieved with asymetric crossover slopes 2. Position the woofer to minimise the 5th harmonic pipe resonance in very tall enclosures 3. Place the woofer appropriately in a desired transmission line Essentially - driver orientation, as well as off centre baffle placement are merely different solutions to the same problems. With speaker building there are often (at least) a couple of solutions to each problem. David.

5th July 2008, 01:18 PM	#6
rabbitz diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	Inverted drivers are at times used with odd order crossovers to compensate for the downward polar tilt caused by phase difference between the high and low pass sections. If the geometry of the drivers are done correctly then you can get a +15° tilt from the drivers which compensates for the -15° tilt from the odd order filter. Result ZDP (zero delay plane) becomes 0°.... sort of a pseudo time alignment. There's some info on it in the Loudspeaker Design Cookbook (7.23 in 6th edition).

5th July 2008, 03:04 PM	#7
tinitus diyAudio Moderator Join Date: Nov 2005	I know a skilled and VERY critical designer, who would never do that, but he actually ended up doing just that, so yes I suppose it can be done right ... as rabbitz points out, if you know what you are doing

5th July 2008, 11:01 PM	#8
forr diyAudio Member Join Date: Dec 2004 Location: Next door	I suggest to play with Edge : http://www.tolvan.com/ to observ the diffraction effects on a tweeter positionned on a more central position than usual.

5th July 2008, 11:30 PM	#9
Andy G diyAudio Member Join Date: Apr 2002 Location: Newcastle, Australia	As Dave said, this type of design is often required in folded pipe designs , where the main driver needs to be at a specific position in relation to the pipe. This invariably (because of the way things need to be done) puts the woofer at the top the box, near the fold. So it is generally the woofer position that forces this type of design. That being said, so long as you watch the acoustic axis of the x-o, there should not be any problems.

6th July 2008, 10:34 AM	#10
tpsorin diyAudio Member Join Date: Jun 2005 Location: Timisoara	One benefit, I can think of, is to have tweeter at ear level in case of very tall speaker, or in case that you listen from bed. I don't think there are many other differences.

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