I know this has been discussed briefly before, but I want (hopefully) to address a new aspect of it.
It is becoming more common for speakers, bookshelf and floorstanding, to have Down Firing Ports, though certainly still in a minority.
Here is an example of a modern speaker with a Down Firing Port -
Canton Reference 3.2 DC loudspeaker | Stereophile.com
Also this concept has been applied to the new Wharfedale Diamond 100 series, not yet released in the USA. Even the bookshelf have Down Firing Ports.
Determining the Port size is easy enough, but what concerns me is the Gap between the Port and the Floor or the Plinth. If the Gap is too small, then the Gap becomes part of the Port and throws off the tuning. I'm not sure what happens if the Gap is too large, perhaps nothing of relevance.
But that is precisely the question, how much is too little Gap and how much is too much Gap?
Has anyone worked out the underlying science for determining the size of that Gap? Or at least someone might have some guidelines or rules of thumb.
The concept seems like a good idea, but other than Gap Size, what are the pitfall of using Down Firing?
Also, if you were building a Down Firing Box, would you build a plinth or stand, or let it fire directly down onto the floor? And if into the floor, what effect would different floors have? For example, would Down Firing into carpet be an advantage or disadvantage?
Applying the same concept but in a different way, Polk Audio has a Rear Firing Port that has a re-director panel on the back that redirects the port output to the sides. Centered on the Port is a teardrop shaped area to smooth the transition (one assumes) from rear-directed to side-directed port output.
But even in the above Polk example, the issue of the Gap arises.
I suppose the same question could be applied to the Down Firing Sub. That Gap between the Port and the Floor has to have some effect on things. But what?
Which brings up an addition issue "The Tear" or dome/cone/whatever just under the center of the port to smooth (one assumes) the re-direction. Is this valid or is it just cosmetic hype?
But the Primary issue is -
How does changing the size of that gap effect the final result?
I'm assuming, and perhaps this is where I am wrong, that the ideal Gap is neutral and has no effect on the loading or resonance of the Port.
I'm open to hearing any discussion on the idea of Down Firing Ports, whether general discussion or directly addressing the Gap issue.
Thanks to any help people can give.
Steve/bluewizard
It is becoming more common for speakers, bookshelf and floorstanding, to have Down Firing Ports, though certainly still in a minority.
Here is an example of a modern speaker with a Down Firing Port -
Canton Reference 3.2 DC loudspeaker | Stereophile.com
Also this concept has been applied to the new Wharfedale Diamond 100 series, not yet released in the USA. Even the bookshelf have Down Firing Ports.
Determining the Port size is easy enough, but what concerns me is the Gap between the Port and the Floor or the Plinth. If the Gap is too small, then the Gap becomes part of the Port and throws off the tuning. I'm not sure what happens if the Gap is too large, perhaps nothing of relevance.
But that is precisely the question, how much is too little Gap and how much is too much Gap?
Has anyone worked out the underlying science for determining the size of that Gap? Or at least someone might have some guidelines or rules of thumb.
The concept seems like a good idea, but other than Gap Size, what are the pitfall of using Down Firing?
Also, if you were building a Down Firing Box, would you build a plinth or stand, or let it fire directly down onto the floor? And if into the floor, what effect would different floors have? For example, would Down Firing into carpet be an advantage or disadvantage?
Applying the same concept but in a different way, Polk Audio has a Rear Firing Port that has a re-director panel on the back that redirects the port output to the sides. Centered on the Port is a teardrop shaped area to smooth the transition (one assumes) from rear-directed to side-directed port output.
But even in the above Polk example, the issue of the Gap arises.
I suppose the same question could be applied to the Down Firing Sub. That Gap between the Port and the Floor has to have some effect on things. But what?
Which brings up an addition issue "The Tear" or dome/cone/whatever just under the center of the port to smooth (one assumes) the re-direction. Is this valid or is it just cosmetic hype?
But the Primary issue is -
How does changing the size of that gap effect the final result?
I'm assuming, and perhaps this is where I am wrong, that the ideal Gap is neutral and has no effect on the loading or resonance of the Port.
I'm open to hearing any discussion on the idea of Down Firing Ports, whether general discussion or directly addressing the Gap issue.
Thanks to any help people can give.
Steve/bluewizard