In the floor-standing speaker with dual woofers, closed-enclosure system, is it necessary to divide the chambers for each woofer? I’ve seen both dividing-chamber type and not. Which one is better? And what is the purpose/advantage of dividing chamber? Thank you
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If the two drivers are the same and fed the same signal a shared chamber is optional. If the drivers and/or the signals they receive are different separate chambers are required.
I agree with CowanAudio ... However, since splitting the chambers is almost always just an extra piece of wood that also adds bracing in your enclosure, I'd say splitting the chamber does make sense.
It makes no difference. The woofers automatically split the chamber, that is to say they make balanced use of it.
It gets kind of obvious when you have one built ... tap one woofer gently to make it move in and the other one moves out. That is to say they will interact with each other in negative ways ... if they are not matched in sensitivity and linearity, they will produce cone motion errors that, in some cases, could be audible.
Isolating them prevents that.
I agree with both Allen and Douglas and at the same time disagree.
It depends sometimes on how different the drivers are as they come from the factory and also to how they are wired, series and parallel wiring might be subtly different. The main advantage to using two chambers is so that you can experiment with different "Q" functions in sealed boxes if the drivers are the same specifications. Remembering that for a long time many speakers had different sized drivers with very different specification sharing the same box and some of them sounded very good, usually those speakers used sealed back cone tweeters or were like the big ones from Briggs/Wharfedale with just the 3inch tweeter in a separate compartment
It depends sometimes on how different the drivers are as they come from the factory and also to how they are wired, series and parallel wiring might be subtly different. The main advantage to using two chambers is so that you can experiment with different "Q" functions in sealed boxes if the drivers are the same specifications. Remembering that for a long time many speakers had different sized drivers with very different specification sharing the same box and some of them sounded very good, usually those speakers used sealed back cone tweeters or were like the big ones from Briggs/Wharfedale with just the 3inch tweeter in a separate compartment
I would not divide the chamber into 2. But i would add a brace in (about) the same place with big holes in it. I would also mount the woofers on each side and couple the drivers together to make a push-push woofer where the active force cancelation dramatically reduces loads into the cabinet… you XO need sot be low enuff and where that is depends on the woofer size. With the Silver Flute W14 (5 1/4”) that is as high as 450 Hz.
I see nothing good with 2 chambers, Douglas’ example of push one woofer the other one moves is a good thing, not a bad thing.
dave
I see nothing good with 2 chambers, Douglas’ example of push one woofer the other one moves is a good thing, not a bad thing.
dave
I measure and match the drivers and given how tolerant a sealed box is, this is usually not an issue. If the woofers are different enuff to be an issue, send the bad one back and get a fresh one.
dave
Okay ... I'll concede that I could be exaggerating a bit... so lets explore this.
When you have two speakers in a sealed or acoustic suspension enclosure, assuming a relatively good seal. Pushing one of the speakers in, increases the pressure inside the cabinet. Since the other speaker shares that cabinet it will move outward as a result of that increased pressure. So yes, they do move in opposite directions when only one is influenced.
We can thus conclude that unless they move *exactly* the same way, from the same stimulus one speaker is going to affect the motion of the other. If one moves 5mm and the other only moves 4 two things will happen... first the one moving the farthest will create more pressure, causing the other one to move even less... and the one that moves less will create less pressure causing the one that moves more to move even more.
Now, the question is, does this matter?
I'm saying that in cases where the characteristics are different enough, yes it will... some cone motions will be exaggerated, some will be attenuated... and that is going to colour the sound.
Rebuttals?
When you have two speakers in a sealed or acoustic suspension enclosure, assuming a relatively good seal. Pushing one of the speakers in, increases the pressure inside the cabinet. Since the other speaker shares that cabinet it will move outward as a result of that increased pressure. So yes, they do move in opposite directions when only one is influenced.
We can thus conclude that unless they move *exactly* the same way, from the same stimulus one speaker is going to affect the motion of the other. If one moves 5mm and the other only moves 4 two things will happen... first the one moving the farthest will create more pressure, causing the other one to move even less... and the one that moves less will create less pressure causing the one that moves more to move even more.
Now, the question is, does this matter?
I'm saying that in cases where the characteristics are different enough, yes it will... some cone motions will be exaggerated, some will be attenuated... and that is going to colour the sound.
Rebuttals?
If the difference is significant you have a problem, you have to pack it up and pay for shipping back to the supplier to get a good one. Or you are buying poorly QCed drivers.
dave
I agree... it is likely a QC problem.
But I'm suggesting it is one we can avoid with a simple piece of wood... So why not?