well measured both panels.
The blue line is the panel 0.5mm crosssection of 0.195 mm2 wire and a magnet gap of 1 mm. resistance of 2.3 Ohm
The red line is the foil 5 mm width 40 micron thick, 0.2 mm2 crossection. and a 3 mm magnet gap. and a resistance of 2.4 ohm
both have same amount of turns in magnet field. same amount of magnets used.
difference are not that big. although foil wins.
1. a little bit more sensitivity in the lf response but only a dB or so,
2. impulse looks cleaner.
3. Less 3th harmonic distortion then the wire version.
and i think numer 3 , you can hear verry clearly. the bass sounds way better less floppy.
both measure at 10 cm distance, so the low end will be much less further away , but i wanted to have the driver and not the room so much.
The blue line is the panel 0.5mm crosssection of 0.195 mm2 wire and a magnet gap of 1 mm. resistance of 2.3 Ohm
The red line is the foil 5 mm width 40 micron thick, 0.2 mm2 crossection. and a 3 mm magnet gap. and a resistance of 2.4 ohm
both have same amount of turns in magnet field. same amount of magnets used.
difference are not that big. although foil wins.
1. a little bit more sensitivity in the lf response but only a dB or so,
2. impulse looks cleaner.
3. Less 3th harmonic distortion then the wire version.
and i think numer 3 , you can hear verry clearly. the bass sounds way better less floppy.
both measure at 10 cm distance, so the low end will be much less further away , but i wanted to have the driver and not the room so much.
Attachments
Last edited:
You can get 3mm alu foil here:The Masking Shop - Aluminium Foil Tape
It is selfadhesive.
I can check the resistance if you want it.I think it is 30my.0.030mm.
Bernt
It is selfadhesive.
I can check the resistance if you want it.I think it is 30my.0.030mm.
Bernt
yeah its funny i posted that link once because everyone whas looking for it
hehe but thanks anyways i bought the 3mm and the 5mm i used both in these testsits the stuff i use as well, but its 40 micron as stated by the masking shop
"• 40 Micron Aluminium Foil with Acrylic Adhesive
• Good Temperature resistant up to 150°C
• Excellent barrier against humidity and vapour
• Conducts heat very well"
Yeah, and the foil obviously wins in the upper mid-range, too. But wow it takes a dive just above that.
Maybe if you lower the gap between membrane and magnets to 2 mm with the foil, then the high frequency response could improve enough.
My old Magnepan MG-12/QR have a separate tweeter section, with foil, and the gap is 2mm, there, instead of the 3mm they used for the mid/bass section (which used wires).
Cheers,
Tom
its the other way around as far as i know. the gap in a SMGA is 1.5 mm. i tried looking for magnepans with the QR to see what gap they used but i could never find a picture with the gap. could you measure this ?? or take a look at it ?
the 2 mm for the foil looks logical, but 3 for the wires would be a waste of magnetic field.
im not sure yet why the response takes a dive, my guess is its to heavy. or not enough foil versus mylar. the reason why the magnets in the high fequency are usually smaller so they can fit more foil/wire versus mylar.
i found magnet 3.2mm thick 24.4mm wide right now for 50 euro for 20 meter. if i go for 4-5 mm wide magnets instead of 6 (because mine is thicker 1,2 mm thicker) i could cut 4 or 5 strips. equals around 80 to 100 meters. enouhg for one huge push pull bass panel. still bit expensive for a shot in the dark.
Looks like I was remembering wrong about the 2mm: (It's 1 mm and 3 mm, not 2 mm and 3 mm. But those measurements were approximate, anyway.)
http://www.diyaudio.com/forums/plan...r-magnetic-central-tweeter-4.html#post2884995
http://www.diyaudio.com/forums/plan...r-magnetic-central-tweeter-4.html#post2884995
Thanks Bandsei .....
Interesting topic here , as i had wanted to increase steel bars thickness and wanted to know if this would translate to more sensitivity in real world application ..
http://www.kjmagnetics.com/blog.asp?p=shielding-materials
Interesting topic here , as i had wanted to increase steel bars thickness and wanted to know if this would translate to more sensitivity in real world application ..
http://www.kjmagnetics.com/blog.asp?p=shielding-materials
Last edited:
Could you please tell me where did you get the 3.2 mm thick magnetic material thanks Henry!
Just found this thread, interesting. Magnepan certainly made a lot of "trial and error" over the years to find out what work or not. They have found some combinations that do the trick. Wires from heavy copper AWG24 to thin aluminium AWG36. The flat section wire (foil) is rather thick for the basses. The cross sectional area are similar in order to keep the efficiency up. If you reduce the cross section, you will loose output. Of course, there are ways to improve on their designs. You must know that some things are very hard to realize. The combination of high efficiency and good bass is difficult to get, to say the least. If you increase the field strength, the grip of the voice coil (round or flat wire) will kill the bass. Same thing if you use thinner/lower mass wire. At higher frequencies, efficiency can be inreased or you can lower the moving mass in order to let ease the reproduction of higher frequencies. The distance magnets-to-diaphragm can be made non-constant and it is in some Magnepan. I think it is difficult to predict the outcome of many of the variables. Going push-pull is also difficult. A friend of mine wanted to make an overkill bass driver that way. High field strength in combination with low mass wiring did not work....
Good source for Neo-magnets, Hyab in Sweden. Cheaper than NdFeB Magnet. Neodym und ferrit magnete - Shop ENES Magnet Magnete
Good source for Neo-magnets, Hyab in Sweden. Cheaper than NdFeB Magnet. Neodym und ferrit magnete - Shop ENES Magnet Magnete
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.