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Old 10th August 2011, 01:25 AM   #751
a.wayne is offline a.wayne  United States
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Using ferrite magnets system consist of 240 magnets no way in neo...cheap


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Originally Posted by sonegatti View Post
Costs about 9USD each (with shipping and 10% of taxes), two years ago.
Tell me the new prices if you make an order!
Thanks!!
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Old 28th September 2011, 01:32 AM   #752
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Sorry for the ignorance but what exactly is the difference between the ribbon speakers and plannar?

Seems like I have seen ribbon tweeters and ribbon midrange on the Maggies so I start to get confused. Do the Plannar and Ribbons sound similar?

Seems like a smaller plannar can cover a wider bandwidth, no?
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Old 28th September 2011, 03:42 AM   #753
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Well a planar speaker is mostly called that way because it has a flat transducer.
It has nothing to do with if it has a ribbon tweeter or not.

Most of the time magnetostatic speakers are referred to as planars and electrostatic speakers are not. Even though they are flat.
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Old 10th April 2012, 06:53 PM   #754
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Default Ribbon Pleating Tool

Here is a pleating tool that is totally FREE! get a USPS Priority mail box like the 12 1/16 X 2 11/16 X 13 7/16 size. Cut off pieces carefully of the size needed for ribbon length. Wet them until the brown side comes off easily. After drying, ready to use. These make about 7 total pleats per inch, 14 angles.
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Old 8th September 2012, 06:11 AM   #755
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Quote:
Originally Posted by brunob View Post
I measured the magnetic fields using a Hirst gaussmeter of long and short magnets systems. I did NOT observe a strong decrease the magnetic field in the ribbon gap for a long versus a short system. Seems that FEMM is wrong here.

Bruno
Thanks for that post Brunob; I've had my suspicions about FEMM. Some old school knowledge about magnet shapes had me puzzled as to why neodymium bar magnets are used so religiously in these ribbon designs. The field strength through the length of a cylinder is much better than through the side of neodymium bar magnets. In many designs the choice is an obvious easy way to build it. But others are just a very inefficient approach.(no build advantage to the bar magnets)
Then I made the discovery that FEMM was not showing this much at all (if at all) I realize magnetic field design can be elusive. but generally, a good old fashioned weight lifting test gives you a good idea of what you have got. And on that basis I more than doubled my field strength with cylinders. This is both a cost savings or in the case of those wishing to build an open back (dipole type) ribbon, the efficiency without the back iron. I think some Gaussmeter testing here would give me some relief.
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Old 8th September 2012, 09:33 AM   #756
UKPD is offline UKPD  United Kingdom
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Quote:
Originally Posted by terryaaa View Post
Thanks for that post Brunob; I've had my suspicions about FEMM. Some old school knowledge about magnet shapes had me puzzled as to why neodymium bar magnets are used so religiously in these ribbon designs. The field strength through the length of a cylinder is much better than through the side of neodymium bar magnets. In many designs the choice is an obvious easy way to build it. But others are just a very inefficient approach.(no build advantage to the bar magnets)
Then I made the discovery that FEMM was not showing this much at all (if at all) I realize magnetic field design can be elusive. but generally, a good old fashioned weight lifting test gives you a good idea of what you have got. And on that basis I more than doubled my field strength with cylinders. This is both a cost savings or in the case of those wishing to build an open back (dipole type) ribbon, the efficiency without the back iron. I think some Gaussmeter testing here would give me some relief.
Any pictures ?
Peter
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Old 14th May 2013, 08:41 PM   #757
Legis is offline Legis  Finland
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Hi all ribbon enthusiasts! I'm tempted to build some wide range ribbons myself, they look so fffing simple to build. But some quidance is needed, all opinions are much appreciated.

The magnets:

- Which one of these dimension is better in your opinion in "normal" structure? Does the 0,5" x 0,5" give more concentrated magnetic field than the other for example?

a) 4" x 1" x 0,25": cPath_1_5 | products_id_1056 | N45 Neodymium Magnets 4 in x 1/2 in x 1/2 in Rare Earth Block - Applied Magnets & WindMax Wind Turbines
b) 4" x 0,5" x 0,5": cPath_1_5 | products_id_1056 | N45 Neodymium Magnets 4 in x 1/2 in x 1/2 in Rare Earth Block - Applied Magnets & WindMax Wind Turbines

- Which above dimension would be better if the magnetic structure would be made with two side-by-side magnets (like this Another DIY Ribbon thread).

- In you opinion, is it worth doubling the budget to make the side by side magnets? Does it reduce even order harmonics ~10dB, give 3-6dB more sensitivity etc.?

The ribbon:

- I like the looks of smooth ribbons over corrugated ones. Does the ribbon resonate too much if it's not corrugated? I would maybe just roll it with dough roller to get some tiny-tiny patterns going, at least try it. How Fountek controls the resonances for example? I think they use smooth ribbons.

- 12m aluminized mylar as ribbon material, yes or no? Smoothier FR maybe compared to uncorrugated alu foil, but somewhat reduced efficiency?

The size of the ribbon:

- I would like to be able to play down to ~200-300Hz with some crank-it-up capacity and good linearity, and propably XO 6dB/oct. If the ribbons are 2m tall, how wide the ribbon should be approx? Will 0,5-1" wide ribbon manage it also in dipole configuration, if the baffle width is set appropriately?

General:

- How hard it is to make a very good sounding wide range ribbon, comparable to Magnepan ribbons for example?

- Best source for the magnets?

Last edited by Legis; 14th May 2013 at 08:48 PM.
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Old 17th May 2013, 01:23 AM   #758
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I think the field strength would be stronger the closer the 2 poles are. And use N52 magnets. More expensive, but the strongest available so far. 1/2 inch across should be about right? They are stronger the bigger they are. Steel "U" shaped frame probably doesn't help the field, but sure makes it easier to keep the magnets in place.

DIY 4 Inch Ribbon Tweeter

I don't know much about difference of ribbons. I have seen ones that are pattern dented but most were corrugated. metallized mylar I hear is no good. Too much resistance and easily ruined by power.

I buy the magnets from K & J Magnetics, Inc.
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Old 17th May 2013, 08:17 PM   #759
Legis is offline Legis  Finland
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I have progressed a little and got some quotes for 4" x 1" x 1" neomagnets. N42 grade, no need for stronger (around 200lbs pull force) and the price increases fast with higher grades. Do you think they are too monster sized magnets, pure agony to handle?

I have also simulated the "traditional" and the "double magnet" construction with FEMM and noted their difference. I think traditional magnet system is forgiving if one wants to change the air gap width, and actually the x and z axis "Bl-curve" across the gap to both directions is good if the magnet width is sufficient for the air gap's width.

Double magnet system (the gap between the magnets) needs to be fine tuned for air gap width and does not react too well if it's changed. It seems that with the gap between the magnets it's better to err with too small than too large gap. When tuned right, I think double magnet surpasses the traditional construction. But it would cost humongously to build ~2m tall ribbons with monster magnets, and the construction would weight at least "decetly". With traditional design one gets away with half the cost and half the weight.

Traditional magnet design drives the sides/edges (x axis) of the ribbon somewhat harder than the center, on the other hand the double magnet system drives the sides/edges with somewhat less force than the center. Traditional transitions the force smoothly, double magnet system stays constant long way but then the force transition is more abrupt very close to the magnets. I wonder how this translates to distortion figures.

Regarding "xmax", traditional design gives smoothly falling Bl, that usually means even order distortion (sharp fall in the Bl rises higher/odd order harmonics). With traditional design, and with above mentioned 1" wide magnet and 1" air gap, the "xmax" is still around +/- 7mm (according to FEMM, points where the Bl has dropped around -15%).

I think I will start off with the traditional design. If I go mad in the future, I can always buy more magnets.

Last edited by Legis; 17th May 2013 at 08:25 PM.
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Old 17th May 2013, 08:41 PM   #760
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Legis View Post
.... 4" x 1" x 1" neomagnets. N42 grade....

pure agony to handle?
I doubt you will be able to pull two magnets apart

and I expect two magnet just half a meter apart will come flying and clash like hell

so... how to handle them ?

do I need to say more
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