Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
76.174.106.135
I was curious if anyone had purchased any foil from Magnepan yet ? I was wondering how much is was the size and lengths of the rolls that are available ? I am waiting until I am moved and settled in so I can actually work on my speakers before I order any.
Follow Ups:
Here is a link showing how to cut the foil on these. It at least is easier in concept that totally by hand.
http://www.dahlbergaudiodesign.se/engelska/del3.htm
Cheers
Dahlberg is cutting rather short pieces of foil for his ribbons, about 1.5 m. Nothing like the about 40 m you need to "foil" a bass driver. I am not sure it is a very good idea either as the foil will reduce to possible excursion of the a bass driver. The MG1.7 and MG3.7 bass use a foil that is: 0.005" x .075"
The mids of a 3-series (pre 3.7/3.7i) will need something like 15 m (2x7.5 m) long conductors.
You can buy foil from Magnepan but it will be restricted to the foil used in some of their models.
I have a pair of mids from the Tympani IVa with foil, the same foil as used in the 20-series mids (0.0005" x 0.1"). That foil can be used a older 3-series mids too but you might loose some output level.
Built a custom rig for this exact purpose. How wide do you need it?
I have a spare set of Maggy IIIa panels I would like to redo the mid section only.
my guess it would be very similar to the tweeter section of 1.6QR
let me know if you can supply
So it goes.........
For the mids it will be 0.1" x 1 mil. and I haven't figured out the Bass panel width yet, all I do know so far is that it will be 2 mil. thick. I found that in 1" and 2" rolls I will have to cut to size. the mids are 2 sections of about 30 feet each. the bass panels about 160 feet each.If you have an idea for a jig I would love to see it or read what you have. Thanks
The whole setup cost me several hundred dollars to build and many hours of tinkering. It's definitely not worth your money / time to build it and set it up if you are just doing one set of speakers. Only reason I made it is that I'm designing my own of planar / ribbon speakers.
See the picture below. I happened to have a roll of 1/10" laying around by chance. It's not enough for a full speaker but I can send it to you to see if it'll work for you. I'll make more if needed. Shoot me an email: dorfma05@gmail.com.
Note in the photo the edges look rough. A quick pass with a hard rubber brayer completely smooths it out so that the edges are perfect ($10 tool).
This may be a stupid question but why not just use household aluminum foil? I believe standard cheap stuff (not the heavy duty) is around 1 mil thick.
It would be total pain in the ass for me to cut household foil that narrow accurately in one piece and as many feet as I will need to complete my project. For the midrange I would rather buy it ready to go, each foil trace will be run pretty close to the next one so I need it as perfect as I can get it. For the woofer panels I have no choice but to cut what I need, in the thickness I will need. That by itself is enough cutting for me ! :)
In order to have a similar efficency, the foil should have a similar cross sectional area. It also means the mass of the foil will be the same as for a round section wire. If you reduce the cross sectional area, the resistance increase and the effeicency decrease. The bass drivers need a certain mass of the wires (round or flat wires). If the mass is lower, the low frequency resonance behaviour will be upset, cut off frequency will be moved upwards and low bass will be impossible. It seems that many believe the flat wire have a lower mass.... The Magneplanar drivers does not have very low moving mass. The bass drivers use to have about 40 gram of wires, than add the mass of the Mylar foil and the glue. The tweeters have more mass than a conventional dome tweeter. A flat wire will adhere better to the Mylar but it will "short" the elasticity to some degree. The area covered by the flat wire/the foil cannot flex and if it covers too much of the Mylar it will probably not be very positive for low bass reproduction. The flat wire probably have better cooling properties, can take a little more power before burning a hole in the Mylar.
Roger Gustavsson
HUH ? You lost me somewhere, I thought the whole point of DIY was to work out the bugs and make my project do what I would like it to do. The 1.7 & the 3.7 both make decent bass so I am guessing I can do the same if I do it correctly wouldn't you think ? Absolute worse case, I can always make them into a normal set of MGIII's again.
Edits: 07/12/11
What Roger says -- if you change the resistance and mass of the conductors, you will change the output level of the drivers. Also, as Roger points out, you will change the compliance of the diaphragm (since more of the diaphragm will be bonded to aluminum which doesn't stretch) and that will shift the lateral resonance up in frequency.
When I asked Wendell years ago about replacing the wire on my IVA woofers with foil, he said why mess with the best midbass ever?
I suspect that the mids are a safer bet than putting foil on the woofers. Again, if you're going passive, I'd take Roger's advice and use foil of the same mass/unit length as the original wire. If you're going active you can compensate for any changes in sensitivity.
Changing the LF crossover e.g. to single pole would really require a physical driver redesign or a 3.5-way arrangement. The first you can't do and the second would be challenging but potentially very rewarding.
Changing the HF crossover to single pole would likely be easier, you just push the tweeter XO up to where it is in the 3.7. But that assumes that you have sufficient dispersion in the III's midrange -- so it depends on how wide the III's driver is. If it's too wide, you could reduce its driven area when you rewire it or go to a 1.5-way arrangement in which the whole driver is driven at lower frequencies but only part of it at high ones. Again, XO design becomes more complex.
The step from 3.6 to 3.7 (or 1.6 to 1.7) is more than just going from round section to rectangular section of wires. There are so many ways you can tension and support (tuning butons) the Mylar. It still seems to be a secret what the crossover look like. I have tried to spot it through the fabrics but could not see it. The 1.7 standing next to it had most parts behind the fabrics clearly visible.
Roger Gustavsson
That's part of the DIY thing is it not ? I am waiting for one of the inmates to open up the 3.7 and see what's inside, someone like Steve (hint). You Know pretty soon someone will have to look or make crossover upgrades, it's the nature of us planar inmates ! And I know it's not as simple as just switching out wire for foil and that's it. It's starting from scratch. None of the old X-over stuff will be used it will probably be be on ebay in a while :) . Nothing is getting started until I know the foil specs I need and have a source for it. Same with the X-over parts etc. and it doesn't have to be done next week or anything so I will be patient until everything I need is there !
The foil For the tweeters is $7.50 roll,one roll well do two tweeters.
An when you go to pull your working woffer WIRE off not to rip the mylar.
But not to worry it only $6-700 for Magnepan to redo you SMGa up too the 1.6 if the Price is the same it was two years ago.
But it only money right
I did the, As you say DIY Foil on the Mg2 Tweeters i year a go i got the foil from Magnepan for the 1.6s.
This dose not work for me, I like the 1.6 with the pole peace in the front,an one thing no one is saying is..... You have to put the pole peace on the BACK with the foil or the Mod for me well not get it. Low output An if pushed i can here the Foil.... But after the old wire was off, i put the foil on in 10min.Vary eze
good luck on the DIY.
Hey hgg: I decided to leave the pole piece facing forward when I set them up like they come stock. Then I will be able to hear what all the pole piece forward Hubbub is about.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: