file FSP-MAGICBOX

12 years 1 month ago #3647 by steve_b
Replied by steve_b on topic FSP-MAGICBOX
From an acoustic point of view I can't see much point in the port exiting into the horn. The reason for porting the cabinet is because the horn is too small to be effective at the low frequencies. If the horn is not providing any loading on the drive unit why would it on the sound coming from the port?

With regards folded horns and higher frequencies that is easy. I save any warped ply I have for the back panel and then claim it works like a reflector just like the Nexo device.[img]smileys/smiley4.gif

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12 years 1 month ago #3650 by wafflesomd
Replied by wafflesomd on topic FSP-MAGICBOX
I wanna see what cab comes out of this.

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12 years 1 month ago #3652 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
fair play steve, the horn would just make the port seem longer/flared wouldn't it.

So porting to the outside world would be the better choice.

Do we want a double or a single, though?
a double cab would have the benefit of inbuilt extra mouth area, but obviously be bigger.
But would it be too big?

Also, I'm not sure what nexo device you're talking about, do you mean something like this?

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 1 month ago #3655 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
I dont really see the point of doubles...

For doubles
<UL>
<LI>Better stacking</LI>
<LI>Possibly quicker to set up</LI>[/list]


For singles
<UL>
<LI>More flexability</LI>
<LI>Easier to stack & set upon your own</LI>
<LI>Possibly eaisier storage & transport</LI>[/list]


IMO thats the "for and against doubles" list. Can anyone add to that?

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12 years 1 month ago #3657 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
You can't let the drivers share a rear chamber port network thingamabob like in a single.
Less, louder boxes
more mouth area = more acoustic length

/devil'sadvocate

[url=\"http://users.ece.gatech.edu/~mleach/beraneklaw.html\"]Beranek\'s law[/url]
\'bits of ply round a driver\'

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12 years 1 month ago #3661 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX

Steve_B wrote: From an acoustic point of view I can't see much point in the port exiting into the horn. The reason for porting the cabinet is because the horn is too small to be effective at the low frequencies. If the horn is not providing any loading on the drive unit why would it on the sound coming from the port?


This is from SpeakerPlans:

jsg mashed wrote:

Disco Stu wrote:

JaKe wrote: How about porting into the throat of the horn at well below cutoff of the horn?

JaKe


Thats sort of the idea, only you cant model it, anyone know what the difference would be of porting the box into the throat rather than porting the boxinto the mouth?

Stu


I've modelled this. It has the advantage that the port outputgoes through the horn and can potentially get amplified by the horn. It has the disadvantage that some of the front-cone output will disappear through the port. Basically the same breaks as a series 6th-order bandpass.

The thing that makes it interesting to me is that the horn segment's path delay applies equally to the port output and driver output, and the latter two should be in-phase for the same reason as they are witha reflex cab.


Would you agree Steve?

Also (as far as i can tell) the port can be much smaller (and take up less space in the rear chamber) if it enters the throat of the horn. Because the horn will be acting like a flaired port...

These are good threads for anyone interested...

http://www.speakerplans.com/forum/forum_posts.asp?TID=12655&PN=1 horn discussion
http://www.speakerplans.com/forum/forum_posts.asp?TID=14439&PN=1 horn hybrid

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12 years 1 month ago #3662 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX

Deadbeat wrote: You can't let the drivers share a rear chamber port network thingamabob like in a single.
Less, louder boxes
more mouth area = more acoustic length

/devil'sadvocate


2 singles have the same mouth area as 1 double though!

I almost wrote the sharing rear chamber/ port thing but i didnt think it was that much of a plus..? I suppose it could save a small amount of space... what do you think?

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12 years 1 month ago #3673 by tommysb
Replied by tommysb on topic FSP-MAGICBOX
But if you're porting a shared rear chamber, the tuning will change between 1 'double large' chamber and 2 chambers, with relation to port lengths/widths. Think Stasys x for what i mean.

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12 years 1 month ago #3674 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
I didnt think the change was large enough to warrant a double sized cab to move about....
(other people may think differently tho, thats just my opinion)

I'll find a link to what im on about...

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12 years 1 month ago #3675 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
Since Rog turned himself into a "guest" on SP you cant search for posts under his name. It makes my searches really difficult!

My thread asking about it, http://www.speakerplans.com/forum/forum_posts.asp?TID=16465

And finally i found the original thread... http://www.speakerplans.com/forum/forum_posts.asp?TID=5974

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