Where is the shelf brace attached? If its to the front panel below the driver it has no real effect on the driver per se - just the baffle to which it is attached.
By making a solid contact with the reverse of the magnet the 'holey brace' transfers movement/vibration to at least one other panel - the back (more if possible), and is mechanically linked to the front panel via the frame to several mounting points in a 15" circular pattern which gives better control than a straight bar across the front. The magnet & frame become part of the brace.
The shelf just splits the baffle into 2 peices that vibrate semi independently of each other and then need controlling again. Especially in such a large cabinet. The frame in such a large driver is subject to vibration and potentially movement (depending on material & build) and by 'sinking' this away to another, or several, panels it works as a better brace.
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yeah, I know, clutching at straws to find justification for a brace on the magnet. Seems like a belt and braces approach at best.I am thinking
If Melon is using CSA drawings, the shelf brace is horizontal, parallel to the floor, and about half way up the height of the box. It is attached along all 4 edges to the front, the back and both sides of the box. We can't publish the drawings as they are copyright and permission to publish them has been specifically withheld.
The cast driver frame is clearly substantial and strong. It connects the magnet to the front baffle. Melon and I were suggesting that bracing the front baffle near to the driver frame is equivalent to bracing the magnet in terms of the benefits that Planet10 is looking to gain from a magnet brace, i.e. it transfers vibrations from the driver to all sides of the box.
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If anyone tells you "this is not rocket science", tell them they don't know what they're talking about
Yes imagine a shelf like on a bookshelf but with holes in it
Like an internal belt then? Like they use on box kites and packing crates? What does this thing brace against? Because unless there is a crossmember from front to back thru the middle, or side to side thru the middle, or very large triangular corner pieces its not really bracing. (unless its 12" deep)
Half way up you say? If its there to help reduce the vibration of 4 large panels, in the process created 8 smaller ones which are still very big on a box that size.
If I were undertaking a box this big having spent out on the AN drivers I'd do the holey brace for the magnet and several holey triangular braces. Then industrial rubber of various thickness sticking tile/mdf/ply to the various surfaces and jobs a goodun'
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I don't think that is a brace. It is to hold whatever is in front of the cone.
dave
I've always fancied a disc of metal on the front the driver to spread the loading. Then very long purpose made stainless threaded bolts countersunk into the metal disc. These pass thru the front baffle and the back of the cabinet. Then another metal disc to spread the load and nice big nuts to be torqued up. Ah the dreams
Done right that can be quite effective. If you just make the baffle & back out of aluminum and than use bolts to sandwich the box is an elegant solution.
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hmmm, what's the difference ? we're bracing one item against another, who's to say whether it's to control motion of the driver against the box or the box against the driver.
without a driver its just a box. add the driver and its a giant vibrating coffin - what causes the vibrations? The driver. What vibrates? the box, esp the baffle, the most important panel as it holds the driver. As I described above it will use the driver's chassis as part of the brace to control the baffles vibrations and mechanically sink them to at least 1 other panel
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oooooooh sexy cnc metal work. get me to the nearest 3D mill with one hundred pounds of aluminium sheet and some big brass fittings post haste!!!!
Re shelf braces (from here -- required reading):
The purpose of the holey brace is not really to brace anything (that is a secondary side effect), but to directly transfer the reactional driver energy to panels that are not the baffle, and to increase the amount of panel (and subsequently the amount of damping) that deals with this energy. Ideally one could bolt the driver to the holey brace to increase the energy transfer.
JRKO gets it.
dave
The purpose of the holey brace is not really to brace anything (that is a secondary side effect), but to directly transfer the reactional driver energy to panels that are not the baffle, and to increase the amount of panel (and subsequently the amount of damping) that deals with this energy. Ideally one could bolt the driver to the holey brace to increase the energy transfer.
JRKO gets it.
dave
I'm not sure why a plumber would be needed for a Karlson install.
Below is a 1:1 comparison of Beta15cx in two "equivalent enclosures" - that's a reflex the size of K15's rear chamber and same "apparent fb" as K15. (near-cone examination of K15 shows an excursion null 1/2 octave lower than its impedance fb and around 37Hz)
K15's front chamber even on single tone sine-wave reduces cone excursion at 36Hz 20vrms signal to less than half that of the reflex.
Modulation distortion, mixed per Klipsch shows the Karlson to have 10dB less sideband activity than the reflex.
12LTA has a physical voice coil overhang of 0.08" and while having excellent sensitivity is outclassed by Eminence's 80 and 109oz magnet coaxials made for pro monitor use. The difference mainly shows on percussion transients - of course there's also more power in the treble from a compression driver working from say 3KHz upwards than a fullrange driver with its helper kicking in from ~^-8KHz or so.
Small signal response wise, a regular Karlson has no LF extension advantage over a reflex. At large signals, it may very well take advantage as the reduction in cone excursion below the passband and chaotic effects from beat-tones in the passband can help a fullrange (or coaxial) driver whose excursion needs to be kept low for clarity.
when I said Super15 had a weak motor, that's not a cut on its design or performance - just an observation of its electrical q which nudges it towards larger enclousures.
I'm familiar with Super8 and Super10 Nirvana stamped frame drivers and know the latter in a small (~80 liter) 41Hz tuned reflex is rather tragic in bass capability. That must be why David tunes higher. Also, my Super10 are off spec with regards to fs and qts.
Below is a 1:1 comparison of Beta15cx in two "equivalent enclosures" - that's a reflex the size of K15's rear chamber and same "apparent fb" as K15. (near-cone examination of K15 shows an excursion null 1/2 octave lower than its impedance fb and around 37Hz)
K15's front chamber even on single tone sine-wave reduces cone excursion at 36Hz 20vrms signal to less than half that of the reflex.
Modulation distortion, mixed per Klipsch shows the Karlson to have 10dB less sideband activity than the reflex.
12LTA has a physical voice coil overhang of 0.08" and while having excellent sensitivity is outclassed by Eminence's 80 and 109oz magnet coaxials made for pro monitor use. The difference mainly shows on percussion transients - of course there's also more power in the treble from a compression driver working from say 3KHz upwards than a fullrange driver with its helper kicking in from ~^-8KHz or so.
Small signal response wise, a regular Karlson has no LF extension advantage over a reflex. At large signals, it may very well take advantage as the reduction in cone excursion below the passband and chaotic effects from beat-tones in the passband can help a fullrange (or coaxial) driver whose excursion needs to be kept low for clarity.
when I said Super15 had a weak motor, that's not a cut on its design or performance - just an observation of its electrical q which nudges it towards larger enclousures.
I'm familiar with Super8 and Super10 Nirvana stamped frame drivers and know the latter in a small (~80 liter) 41Hz tuned reflex is rather tragic in bass capability. That must be why David tunes higher. Also, my Super10 are off spec with regards to fs and qts.
An externally hosted image should be here but it was not working when we last tested it.
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