I thinking about an easy way to do magnet attachable grilles for the Mark Audio drivers.
I've found some grilles that are of a light but quite magnetic metal exactly matching the diameter of the driver.
I was thinking about putting six small neodym magnets (5x2 milimetres) in the cavities at the back of the drivers flange, secured with blue putty.
My question is now: Is there any chance that this will have a bad lasting/non-reversible effect on coil, magnet or diaphragm?
And if they are placed symmetrically, will it have any effect at all?
I've found some grilles that are of a light but quite magnetic metal exactly matching the diameter of the driver.
I was thinking about putting six small neodym magnets (5x2 milimetres) in the cavities at the back of the drivers flange, secured with blue putty.
My question is now: Is there any chance that this will have a bad lasting/non-reversible effect on coil, magnet or diaphragm?
And if they are placed symmetrically, will it have any effect at all?
Do you mean attaching the magnets to the back of the grille flange?
It should be easy enough to align the little 1/4" neo magnets with the position of the mounting screws in the driver flanges, but they are very strong and I'd suggest a dab of metal bearing epoxy glue on the back of the grille flange rather than relying on the blue putty.
Mark can answer whether the proximity or polarity of the magnets would affect the speaker's motor, but my intuition is "no".
It should be easy enough to align the little 1/4" neo magnets with the position of the mounting screws in the driver flanges, but they are very strong and I'd suggest a dab of metal bearing epoxy glue on the back of the grille flange rather than relying on the blue putty.
Mark can answer whether the proximity or polarity of the magnets would affect the speaker's motor, but my intuition is "no".
No. I thought of doing that at first. But I figured it would be better to put larger stronger magnets in the curved rectangular cavities on the back of the flange of the driver.
It would be easier to align the grille perfectly that way (although you have to do it again every time you take it off), even though the magnet has to pull through ca. 2mm of plastic that way.
But my guess is also no, since the drivers will tolerate being in the same cabinet as their twins or other unshielded drivers with much stronger and asymmetric fields.
Have you tested magnet's ability to hold through that thick a layer of the plastic flange? And which Mark Audio drivers did you have in mind? To be honest, I've not put a caliper on the depth of the casting web on back of flanges of any of them, and the Alpair7 have a cast integral gasket with no such cavities. You might well find that a magnet with appropriate strength to hold through the flange would be thicker than the cavity's depth and need to be be countersunk into the baffle - still doable, but additional complication.
Would there be an option for a larger diameter grill that would still fit your enclosures for which the magnets could be flush mounted outside the perimeter of the plastic flange?
Would there be an option for a larger diameter grill that would still fit your enclosures for which the magnets could be flush mounted outside the perimeter of the plastic flange?
Oh sorry, it's just plain old CHR-70s gen. 3.
I have tested and the magnets will hold through that thickness.
The elegant thing about my method is that nothing is fixed. If you find out the alignment is terrible you just move the magnets. My experience is that aligning something with magnets can be very finicky. Esp. with something as irregular as a grille.
I have tested and the magnets will hold through that thickness.
The elegant thing about my method is that nothing is fixed. If you find out the alignment is terrible you just move the magnets. My experience is that aligning something with magnets can be very finicky. Esp. with something as irregular as a grille.
Guards
Here's my low-brow approach to simple magnetic grilles. Neo magnets on the driver screws and just the steel screen portion of the inexpensive Madisound metal grilles.
I just use them to protect the drivers when I'm away from the office. I think these particular screens take something away from the EL70s. I'm still waffling on what to do for grilles when these go home (kid protection).
I'd also be interested in the Mark Audio perspective about magnetic fields and whether these powerful magnets might cause something wonky in the drivers' motors/coils.
Here's my low-brow approach to simple magnetic grilles. Neo magnets on the driver screws and just the steel screen portion of the inexpensive Madisound metal grilles.
I just use them to protect the drivers when I'm away from the office. I think these particular screens take something away from the EL70s. I'm still waffling on what to do for grilles when these go home (kid protection).
I'd also be interested in the Mark Audio perspective about magnetic fields and whether these powerful magnets might cause something wonky in the drivers' motors/coils.
Attachments
My name isn't Mark, but after a lot of prompting by Dave I've been using the little 1/4" rod rare earth magnets on grilles for some time now; recessed flush into driver baffle, and generally buried beneath finish veneer, but they can be left exposed on bamboo plywood - careful use of drill press and brad-point / forstner bit will avoid any chip-out on finished surface. Using either 1/4" or 3/8" MDF a very light frame can be fabricated with plenty of clearance to the emitting surface. I honestly can't hear any difference with them on or off, but better ears might. For most enclosures a magnet in each corner will suffice. For my own CastleMTs I made a one piece L-shaped 3/8" frame and set the magnets flush to the inside. Once they're upholstered the fabric will cushion the magnets from scratching the enclosure's finished surface.
These little buggers are pretty strong, but I think it would take quite a few of them very close to the existing drive train motor to wreak any havoc.
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Noted, thank you both.
Evan actually made me some nice U-shaped frames which I have yet to cover. So the truth is I'm just noncommittal on the fabric-plus-reinforcement idea. I tried cutting some pieces of aluminum window screen, but the threads kept coming loose and I only succeeded in snagging my pants.
I imagine fiberglass would be similar, so I'll look for some nylon window screen next.
Cheers!
Evan actually made me some nice U-shaped frames which I have yet to cover. So the truth is I'm just noncommittal on the fabric-plus-reinforcement idea. I tried cutting some pieces of aluminum window screen, but the threads kept coming loose and I only succeeded in snagging my pants.
I imagine fiberglass would be similar, so I'll look for some nylon window screen next.Cheers!
Dave I have seen that you need 15 000 gaus magnet strength to affect credit card
it was done on one very well know tv show aired on Discovery channel. They did it with electromagnet. 0r was it 10 000? anyway, it was many times more then any magnet they have tried. Even neodymium.Hello everyone, sorry for upping an old thread, but since it seemed pertinent I thought it might be better to post here rather then creating a new dedicated thread.
I am going to build some Frugel Horns MK3 with MarkAudio Alpair 7.3 drivers and, since I have two very inquisitive 3year old twins I wish to protect the drivers from their probing little fingers...
I think I read somewhere (can't recall where) on this forum that MarkAudio sell protective grills cut to the size of their drivers that attach to the screws fixing them to the cabinet, am I allucinating? The MarkAudio web site is momentarily unavailable so I don't know how to verify this, and I haven't found them in any online shop... Please can anyone clarify this to me? Or sujest alternative solutions....
Thank you all very much, and happy new Year!
I am going to build some Frugel Horns MK3 with MarkAudio Alpair 7.3 drivers and, since I have two very inquisitive 3year old twins I wish to protect the drivers from their probing little fingers...
I think I read somewhere (can't recall where) on this forum that MarkAudio sell protective grills cut to the size of their drivers that attach to the screws fixing them to the cabinet, am I allucinating? The MarkAudio web site is momentarily unavailable so I don't know how to verify this, and I haven't found them in any online shop... Please can anyone clarify this to me? Or sujest alternative solutions....
Thank you all very much, and happy new Year!
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I don't think Mark offers grilles himself, and a concern that I failed to mention in the previous discussion on this thread is the risk of damage to any of the Alpair or CHR drivers' VERY delicate metal cones. Call me an alarmist, but I speak from experience as to their fragility. Sure the neo magnets attached to the mounting screws would be more than capable of holding a small metal grille, but unless the kids aren't as curious as mine were or never see you remove the grilles for "critical listening", ("well, daddy did!") they'd still likely experiment. Even a very steady hand can slip, and it takes only a glancing stroke with your fingertip to crease the metal cones.
. The FH3 front baffle is certainly wide enough to use either a DIY MDF framed / fabric grille and flush mounted magnets, or a more robust metal grilles such as the Madisound house brand G6.5.
An externally hosted image should be here but it was not working when we last tested it.
Due to the 7.3's generous flange, particularly when using the extra bezel ring, you'd need a clear 135mm internal opening on the grille's mounting ring . I wouldn't want to risk mounting the smaller G5.25's lower ring under the 7.3's flange.
Thank you very much Chris, I'll try to see if Madisound will ship to Italy, or if I can find some local equivalent.
My children know that the hifi equipment is a strictly off-limits area, but every time I turn my back... Well lets just say they are extremely lively! I'd better equip my soon to be' FHMK3s with some sturdy protection!
My children know that the hifi equipment is a strictly off-limits area, but every time I turn my back... Well lets just say they are extremely lively! I'd better equip my soon to be' FHMK3s with some sturdy protection!
Thank you very much Chris, I'll try to see if Madisound will ship to Italy, or if I can find some local equivalent.
My children know that the hifi equipment is a strictly off-limits area, but every time I turn my back... Well lets just say they are extremely lively! I'd better equip my soon to be' FHMK3s with some sturdy protection!
Yes, kids make life interesting (as I'm sure our own moms would attest)
International shipping might well be more than the cost of grilles. I'd be surprised if a similar product to Madisound's house brand wasn't available from a closer supplier - particularly of car audio gear - just pay attention to the internal opening of lower mounting ring.
While you're thinking about "kid-safeing" (no such thing as "kid-proofing") the speakers, note that the FH are skinny enough that a stabilizing base plate or outriggers are worth considering.
Yup, IIRC he quoted a very reasonable price on those a while back - just be wary of pointy spikes - not so much for the tikes, but the floors. I've managed to damage both carpeted and hardwood floors over the years, and tend to prefer blunt or rounded tips to the needle points.
The magnets and metal grilles have worked very well so far... I have been very careful to not let the little people see me remove them. However, just a few days ago, my 4 yr old son exclaimed "Magnets!" and I knew exactly what was up. He'd slid them around a bit, but no major messing around. I'll be covering the grille frames with cloth soon to put over the metal ones.
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