file FSP-MAGICBOX

12 years 1 month ago #4063 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
Passive radiators get me thinking about Acoustic Levers and Servodrive....mmm.....seeerrvooo

[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 #4064 by rich_gale
Replied by rich_gale on topic FSP-MAGICBOX
what i meant was a passive radiator cabinet using 2x active 12" drivers and a single 18" Passive.I did mean the throat of the horn, using it on the mouth would probably lead to some very weired outcomes. The config would mean the passive radiator is coupled to the horn. The reason i suggest a PR is that i believeit allows a significant cut on internalvolume compared to thatrequired for the same tuning in reflex cabs.

The PR would need to have a significant excursion capability. a rubber edgedpd 18"with no magnetis what i got inmy mind- and I got a feeling i was told that pd were working on a new rubber edge driver withsimilar designcriteriato the mccauley 6174. the vc could be replaced with a aluminium block(onto which you could attach different weights for tuning)

could be something that would work, or could be a big waste of money and not offer any more benefit than just 2 12" cones in a scoop or horn assisted reflex.

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12 years 1 month ago #4073 by jake_fielder
Replied by jake_fielder on topic FSP-MAGICBOX
oh, i see what you mean now. thats really interesting!

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12 years 1 month ago #4074 by arksystems
Replied by arksystems on topic FSP-MAGICBOX
Wow! this is clever stuff on this thread..PR's are my fav for home hifi .I have some old Celestion ditton 15xranda Pair of B&W DM7s in my front room at the mo!The bass from just the B&Ws is enough to make you feel sick when listened to at high volumes .Real low Sub!
With regards to resonant chambers I have an old box in the attic which used to be loaded with a 10 inch Stentorian full range driver...from the front it looks like a normal reflex box but when the driver is out you see a dividing panel above the port of 3 ply with lines sawn into it??I'm guessing it resonateswith the bass?or is it a form of bandpass?Will take some pics if anyones interested as thebottom endfrom it was superb.Edited by: ArkSystems

Dave Martin is alive and living in my kitchen.

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12 years 1 month ago #4077 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
Whiteley Stentorian cabs...
Seen quite a few of those. I seem to remember a thing like that as well, will get back on that. How thick are those sawn lines? I'd be interested in a picture [img]smileys/smiley4.gif

PRs are nice, all the port without the chuff.

[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 #4082 by rich_gale
Replied by rich_gale on topic FSP-MAGICBOX


The pd.12sb30 has a heartyxmax of 7mm, though its sensitivity is only 96db. if a similar 12"driver is available with a nice xmax and higher efficiency it could work a treat. tune low with the PR and horn load the output from the PR. has anyone ever tred removing the magent structure from a pd driver? they got some allen heads on the inside of the basket and i was wondering if it will just be a case of unscrewing these? oris the magnet alsoglued in place?

Cab is looking big at the moment, but im sure this could be squeezed into a LAB footprint.

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12 years 1 month ago #4110 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
The PR would be moving the most at it's tuned resonant frequency, as you know (It is used in lieu of a BR, as it is mathematically identical being a mass on a spring), and has an 18dB/octave dropoff. Then there's the phase response problem (which will be accentuated with the horn loading). The horn would cover half an octave, I think. I can see the cabinet working, but I can see a 15" scoop doing a similar job.

As per usual, YMMV, so please don't go all out guns drawn on this one. [img]smileys/smiley1.gif

[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 #4134 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
Just been taking hornresp to it's limit and am in the process of reinventing my cab one more time[img]smileys/smiley36.gif.

You can model a host of undocumented enclosures in hornresp...apart from double horns and passive radiators (Maybe in the next cycle...). Imagine what you could do if instead of a ported rear chamber you could simply have more S1/2/3/4/5...

PS

This might get even more twisted when I bother to buy SPEAK.

[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 3 weeks ago #4445 by deadbeat
Replied by deadbeat on topic FSP-MAGICBOX
Just so we can wrap this up - the thread's requirements have been met by the JF folded horn for the moment, though other designs should appear if others take interest, and definitely after I get further down my to-do list (currently on FSP-ARRAY)

[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 3 weeks ago #4448 by wafflesomd
Replied by wafflesomd on topic FSP-MAGICBOX
That was no fun :(

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