Hi, Is there any problem if I put in the middle of a slot port, a little piece that acts as a port bracing along it? (red color on picture below). That bracing piece does not take any of the required port area (I make port a little bigger considering the space that brace will take). Is that so simple? Because I will put some bracing inside the enclosure, I thought that I also should brace that middle section of the port in that way. Thanks.
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Is that so critic? "bending the port a lot" I actually have a port design that''s even more extreme, which has 4 bends, I think it will sound ok as long as you put some corners on every bending, so you help the air flow, also that port has big area, 13.16", more than enough for a powerful 8" driver.
I am also interested on passive radiators, but how low would be able to go with even a pair of passive radiators? with the port I can be able to tune a no more than 1.7 cubic foot enclosure to amazing 26hz, that's I also want to know if the passive radiator can match or beat what port gives, if so, how many radiators, just with one? or does it turns more interesting when using more than 1 radiator? thanks.
Quite! Further, a very good rule of thumb for round ports is to use a length of no more than twice the diameter. A very long port increases losses and will introduce pipe resonances which could be problematical. Whilst a slot port is convenient to make, it will always need to be longer than a round port of the same area.
Cheers, Carl.
Passive radiators can match and usually beats ports when box volume is not so big and when calculated port length is very long.
Passive radiators have their own parameters, use a software simulator (you can tune PR with some additional weight).
One 12" passive radiator should be enough for a 8" woofer.
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But that 8" woofer will be a lot different from the average 8" woofers, because of its power and stiffness, is not it like in this case, we need a passive radiator as stiff as the sub is? you know, very hard surround and spider, just like the sub specs, surely if I get a passive radiator, it won't be as stiff as the sub. Does not that matters?
Data sheet for Dayton Audio SD215-PR Passive Radiator:
http://www.parts-express.com/pedocs/specs/295-492-dayton-audio-sd215-pr-specifications-46183.pdf
Resonant frequency Fs=21 Hz
Data sheet for Dayton Audio SD270-PR Passive Radiator:
http://www.parts-express.com/pedocs/specs/295-494-dayton-audio-sd270-pr-specifications-46184.pdf
Resonant frequency Fs=19.5 Hz
Data sheet for Dayton Audio SD315-PR Passive Radiator:
http://www.parts-express.com/pedocs/specs/295-496-dayton-audio-sd315-pr-specifications-46185.pdf
Resonant frequency Fs=16.8 Hz
You must use a software simulator for YOUR 8" woofer and for the planned PR!
http://www.parts-express.com/pedocs/specs/295-492-dayton-audio-sd215-pr-specifications-46183.pdf
Resonant frequency Fs=21 Hz
Data sheet for Dayton Audio SD270-PR Passive Radiator:
http://www.parts-express.com/pedocs/specs/295-494-dayton-audio-sd270-pr-specifications-46184.pdf
Resonant frequency Fs=19.5 Hz
Data sheet for Dayton Audio SD315-PR Passive Radiator:
http://www.parts-express.com/pedocs/specs/295-496-dayton-audio-sd315-pr-specifications-46185.pdf
Resonant frequency Fs=16.8 Hz
You must use a software simulator for YOUR 8" woofer and for the planned PR!
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Can I use two of 8" or 10" for the 8" high power subwoofer? Do radiators work with extremely power subwoofers? there is a 8" skar subwoofer that holds 900w rms, I am curious if it would work using these passive radiators, which I don't think are as solid and stiff as that subwoofer is.
Not obvious to me!
I think its the same than using tubes, however slot ports have the advantage that you can adapt it so nice to the walls, being the walls part of the port, here an example, btw I am trying to find a balance in volume and port length, so the port will only have two 90 degree bends. Mounting hole is in the same port hole board, I just made that circle representing the sub magnet, which will be between two 2x2 bracing crosses.
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Borg audio: Okay, I break it down.
Difference 1: The slot port uses the wall as a part of the bassreflex. The better case is, when it ends in the "half" of the box. Then it uses the some part of the continuing wall as a part of the bassreflex, making it vitrually longer than it really is. When you end your bassreflex closer to the "corner", it uses the opposite wall too, effectively making it very long bassreflex. When I simulate my "slot" reflex boxes, I often get 85cm long reflex in the simulation, while in real box, it´s just 50cm.
Difference 2 : Round port is most "effective" As the air touches the least static surface area, there is the least friction of the air. If you go slot, there is significantly more friction area, and the air doesn´t really want to go into sharp corners (of my triangular reflexes). It has its advantages and disadvantages. But the outcome is that the bassreflex looks like it has virtually less cross section are, thus again tuned little lower.
Difference 1: The slot port uses the wall as a part of the bassreflex. The better case is, when it ends in the "half" of the box. Then it uses the some part of the continuing wall as a part of the bassreflex, making it vitrually longer than it really is. When you end your bassreflex closer to the "corner", it uses the opposite wall too, effectively making it very long bassreflex. When I simulate my "slot" reflex boxes, I often get 85cm long reflex in the simulation, while in real box, it´s just 50cm.
Difference 2 : Round port is most "effective" As the air touches the least static surface area, there is the least friction of the air. If you go slot, there is significantly more friction area, and the air doesn´t really want to go into sharp corners (of my triangular reflexes). It has its advantages and disadvantages. But the outcome is that the bassreflex looks like it has virtually less cross section are, thus again tuned little lower.
You can use two or more PR, if needed. PR works with extremely powerful subwoofers, too. PR membranes are made for the same material as subwoofer cones (more or less), so they are as solid and stiff as the most powerful subwoofers are.
Yeah, I will round all the edges. I also modified a little the port model, I was like, hell, why I did not think this before hehe, its a great improvement, 45 degree.
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Does winisd do that function? I am also very tempted with the port, I am now happier with that improvement at the corners, now it bends at 45 degree instead, which does less air resistant. I don't like those huge enclosures that take lot of room, because that I was like omg after seeing you can have an amazing sound in a wonderful compact form factor using that little driver. 900w @23hz with around 50 liter. With those hz you will be able to scare people let them think that an earthquake is coming.
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