Hi,
Beginner question: I will use the bass in an enclosure but keep the midrange and tweeter seperate. The question is how important is it to kill the radiation of the midrange (~500-5000 Hz) from its back? Since these units usually have sealed backs, can I mount them on a thick piece of cardboard? And the same question for the tweeter.
Thanks a lot. Cheeres,
Murat
Beginner question: I will use the bass in an enclosure but keep the midrange and tweeter seperate. The question is how important is it to kill the radiation of the midrange (~500-5000 Hz) from its back? Since these units usually have sealed backs, can I mount them on a thick piece of cardboard? And the same question for the tweeter.
Thanks a lot. Cheeres,
Murat
You must deal with the back wave from all drivers, although since most tweeters are sealed back you can potentially ignore them.
How you deal with the back wave (sealed, aperiodic, TL, open baffle) will determine the response and radiation pattern. Midrange and tweeter lend themselves more easily to OB because the size requirements scale inversely with low frequency cutoff.
The simplest design would be to seal the midrange.
I don't know what cardboard has to do with anything; you can build your speakers from aluminum or pasta or whatever you want, but there are obviously some tradeoffs in cost, strength, damping, etc.
How you deal with the back wave (sealed, aperiodic, TL, open baffle) will determine the response and radiation pattern. Midrange and tweeter lend themselves more easily to OB because the size requirements scale inversely with low frequency cutoff.
The simplest design would be to seal the midrange.
I don't know what cardboard has to do with anything; you can build your speakers from aluminum or pasta or whatever you want, but there are obviously some tradeoffs in cost, strength, damping, etc.
As long as it doesn't rattle, it won't sound that bad. It's a valid method for quick & dirty OB testing.adason said:
murat - what you're describing is an open baffle speaker, which is quite different from a sealed-box speaker. For one, you don't have to deal with internal damping or bracing, which makes it much simpler to design and build. Two, the backwave of the driver won't come through the cone and possibly color the sound in some way. Three, the baffle vibrations will have a much smaller impact on the sound than the vibrations of the walls of a box. Four, the size of the baffle determines the point at which dipole cancellation (6dB/octave, IIRC) occurs, and a larger baffle will lower the rolloff point. Five, the positioning of a dipole speaker isn't the same as doing it for a monopole (non-dipole) speaker.
454Casull said:
Yes - Isn't he ?
""As the the sealed back of midrange also takes care of back radiation greatly, then, what is wrong with a thick cardboard? If I am not wrong as a baffle it will deal with the diffraction at the boudaries of the speker so it is necessary otherwise I would even skip it""
Rob
there is some terminology misunderstanding
you guys have to distinguish if you are discusing the driver or the enclosure
some midranges come with closed back, so called cup, which is designed to limit low frequency response of the midrange driver and make 3 way box construction much easier
in this case it does not matter if placed on open baffle enclosure or into small closed box, frequency response would be the same
offcourse the shape of baffle/enclosure would influence fr response in part....
you guys have to distinguish if you are discusing the driver or the enclosure
some midranges come with closed back, so called cup, which is designed to limit low frequency response of the midrange driver and make 3 way box construction much easier
in this case it does not matter if placed on open baffle enclosure or into small closed box, frequency response would be the same
offcourse the shape of baffle/enclosure would influence fr response in part....
Attachments
I do believe he's talking about the speaker as a whole, otherwise the whole thing about cardboard would never have come into play.RobWells said:
All,
Thanks a lot for your responses.
I also belive that there is a terminology problem (at least I have). I am talking about the drivers. If I don't see the cone from behind of the speaker then I am calling it "closed" and all (it means a couple for me🙂 ) I have seen are closed in that sense. For example:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=280-250
is not cup but it is closed in my sense; I don't see any opening at the back. It is all metal covered. Adason, would you call it closed or not? Does it have to go into a wood enclosure? Thanks again,
Murat
Thanks a lot for your responses.
I also belive that there is a terminology problem (at least I have). I am talking about the drivers. If I don't see the cone from behind of the speaker then I am calling it "closed" and all (it means a couple for me🙂 ) I have seen are closed in that sense. For example:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=280-250
is not cup but it is closed in my sense; I don't see any opening at the back. It is all metal covered. Adason, would you call it closed or not? Does it have to go into a wood enclosure? Thanks again,
Murat
yes, murat, it is a driver with closed back
sealed back is the other term
no, it does not have to go into a wood enclosure
as a matter of fack, it does not need enclosure, small baffle is just fine
it, however need some sort of baffle, for the difraction reasons
feel free to experiment with any material
the reason why people work with wood is availability and ease of manipulation
there are far better materials than wood
Thanks one more!
Does the baffle size matter? I can make it quite large; 15 in. or even larger. It seem like that would just lower the frequency at which the diffraction will start. And I belive this would be a (+). Any comments on this?
And my feelings says that the distance between midrange and tweeter shouldn't matter as long as the diffraction is considered. Because neither of the drivers would be symmetrical wrt the other. I mean, one driver cannot "surround" the other one in a circular symmetry; hence there won't be strong diffraction. Is this correct?
Murat
Does the baffle size matter? I can make it quite large; 15 in. or even larger. It seem like that would just lower the frequency at which the diffraction will start. And I belive this would be a (+). Any comments on this?
And my feelings says that the distance between midrange and tweeter shouldn't matter as long as the diffraction is considered. Because neither of the drivers would be symmetrical wrt the other. I mean, one driver cannot "surround" the other one in a circular symmetry; hence there won't be strong diffraction. Is this correct?
Murat
it does with the open back midrange, it does not in your case with sealed back midrange
make it as large as your woofer box, so it looks good
15" is enough, offcourse the larger the better, see dick olshers basszilla for inspiration
placing the midrange a little of side is better, not precisely in the center
i do not know if i understand second part
but puting the tweeter as close to the midrange is generaly a good practise
Think polar response. Of course it matters!
I really think you should read about the basics of loudspeaker design. People here are very helpful but you are asking for an almost stream-of-conciousness tutorial of the basics. It is better to learn on your own and then ask questions when you get stuck.
I really think you should read about the basics of loudspeaker design. People here are very helpful but you are asking for an almost stream-of-conciousness tutorial of the basics. It is better to learn on your own and then ask questions when you get stuck.
- Status
- Not open for further replies.