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Old 20th October 2004, 04:50 PM   #31
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It wouldn't work very well for longer ribbons, but making the ribbon out of a stronger material might solve the bending problem.

For example, a titanium ribbon or a titanium diboride ribbon might be suitable, and the higher electrical resistivity would actually be a benefit.
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Old 20th October 2004, 05:15 PM   #32
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Quote:
Originally posted by 454Casull
It wouldn't work very well for longer ribbons, but making the ribbon out of a stronger material might solve the bending problem.

For example, a titanium ribbon or a titanium diboride ribbon might be suitable, and the higher electrical resistivity would actually be a benefit.
The problem that I see with making long ribbons stronger/stiffer
is resonance.[obviously depends on chosen operating frequency]
My own experience with stiffer materials is one of increased
resonance in undesirable areas.

My own thinking is along the line of using a lossy but stiffer material , perhaps a foam or paper with
the conductor bonded to it to produce a light weight reasonably
stiff [where it needs to be] but 'critically' damped ribbon.
Perhaps with something such as above it would then be best
run a line of these ribbons in series to enable the ideal ribbon dimensions to be maintained whilst increasing the effective radiating area/ribbon length.
Effectively having one long ribbon divided into optimal sections.


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Old 20th October 2004, 08:08 PM   #33
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OK, OK the iron / steel joke was stupid, but not even laughing at SOME attempt to be funny, is mean

For the rest I agree with setmenu we thought about titanium, settled on the idea that long supported ribbons, that are curved so that the various "point - ish" sources don't interfere (too much)with each other and radiate nice and wide... still don't have excursion though... and any degree other than vertical you get gravity... so you get some sag... then thought maybe Elac 4pi has a point... and then remembered the little problem of not being dipole anymore...

Now I just want 50 x curved 100 mm neodymium to play with...
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Old 21st October 2004, 02:26 AM   #34
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How much ribbon displacement do we need for home audio?

Prolonged exposure to > 85 db SPL can cause hearing loss. 94 db at 1m = 85 db at 8m, which is a good size room. A 110 db @ 1m design would seem to have enough margin. For a long ribbon, a displacement of +/- 0.1" should be capable of 200 - 20,000 Hz at 110 db



What about Doppler type modulation distortion at 1" excursion for a wide bandwidth ribbon?
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Old 21st October 2004, 08:09 AM   #35
FrankWW is offline FrankWW  Canada
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Yes, Aluminum can be annealed.

http://www.boulder.nist.gov/div818/8...ons/ekin/RSI70(1999)3338.pdf

Instead of clamping the ribbon at the end, suspend it
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Old 22nd October 2004, 12:17 AM   #36
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As for lossy, internally damped material--I've made ribbons out of metallized film from dead capacitors. It works. You can get even short ribbons to have relatively high resistances (I seem to recall having a 10 or 12" ribbon of about 10 ohms.)
With the arguable exception of the floating suspension, I haven't seen anything that hasn't been done before. All the breathless hype is, frankly, annoying. What, it's a susprise that you can put line sources end-to-end for covering even larger areas? Give me a break.
Note that I'm not commenting on sound quality. I have not heard them, and it would be foolish to say one way or the other unless I do. Still, I'm not convinced that they've done anything all that remarkable.
This is all subject to revision if they actually come forth with information instead of sales-speak.

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Old 22nd October 2004, 11:05 AM   #37
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Quote:
Originally posted by GRollins
As for lossy, internally damped material--I've made ribbons out of metalized film from dead capacitors. It works. You can get even short ribbons to have relatively high resistances (I seem to recall having a 10 or 12" ribbon of about 10 ohms.)
With the arguable exception of the floating suspension, I haven't seen anything that hasn't been done before. All the breathless hype is, frankly, annoying. What, it's a susprise that you can put line sources end-to-end for covering even larger areas? Give me a break.
Note that I'm not commenting on sound quality. I have not heard them, and it would be foolish to say one way or the other unless I do. Still, I'm not convinced that they've done anything all that remarkable.
This is all subject to revision if they actually come forth with information instead of sales-speak.

Grey

Metalized film from caps eh?
I have made small ribbons from metalized food packaging did not work too well but interesting nonetheless, the metal thickness on the packaging foils tends to
be around 1-.5 microns and none too even...
My headphone transducers use an etched 30 turns of 0.15mm track width 12micron copper rectangular spiral coil on 9 micron polymide film.
Even 9 micron polymide film is pretty springy stuff , added to the fact that 12 micron of copper is pretty beefy also.
Obtaining small quantities of material for the above can be a real pain, but next material will hopefully be something like 5-9 micron of copper on 5 micron of polymide.
What I would really like to try is a different material entirely, something a little more lossy that is easier to form....

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Old 23rd October 2004, 05:22 PM   #38
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I'm reading the patent now...

The copper buys you a little bit of efficiency, at the cost of weight, so it is rarely used since the weight more than offsets the gain from conductivity. For a LF unit, where mass loading might be good, that's fine.

I think I read the web pages some months back and yawned.

With any long ribbon the transverse wave that travels up and down the ribbon is a problem. As is out of phase sections along the ribbon...

The square wave looks WAY too good for any real world speaker... any real speaker with less than DC to light response *ought* to show some tilt to the waveform - eh?

What he seems to have done is possible come up with a way to increase the flux across the ribbon, but I haven't downloaded all the pages from the patent yet... on a dialup.

The woofer is merely an Adire or Emenince product... nothing exotic about it. So, since their claims are exotic on that, I question their claims in general.

And, if you want to buy enough Neo magnets, you too can have a ribbon speaker with significantly higher output and efficiency than earlier efforts...

(Btw, the Apogees had certain design flaws that at least for me, I don't want another speaker that sounds like they did...)

Signed, Skeptical...

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Old 23rd October 2004, 05:29 PM   #39
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Default Titanium...

Titanium is unsuitable for a practical ribbon. The mechanical properties - it is tough - don't buy you anything in the electrical department. It is also *heavier* than aluminum, iirc.

If you plug into the ribbon equation, you find that you need two things more than anything else: light weight ; lowest possible resistance. That and flux.

As the mass increases and the resistance increases the efficiency goes right out the window, quickly.

Thus aluminum - almost as good as copper in the conductivity, but one heck of a lot lighter... silver? Too heavy. Gold? too heavy,
too soft.

Bummer, eh?

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Old 23rd October 2004, 06:16 PM   #40
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Default Reading the "patent"

Ok, I just scanned the patent quickly... with that in mind I may have missed some key words, but here's my read:

Nothing new, nothing patentable here.

The magnet layout is identical to that of Apogee, so it merely copies earlier art. The use of "soft iron" pole pieces, not new, same as many ribbon mics, and iirc magnetron magnets which were used for some of the 50's design ribbon tweeters.

The use of "booster magnets" - couldn't quite determine what exactly these are supposed to do, or how. The text talks about the deficits of the center rear magnet or magnetic return circuit as far as reflecting sound, but the illustrations and text didn't seem to indicate if the booster mags run all the way up and down the back or if they somehow couple to the side magnets??

Regardless, the claims for Xmax on the website seems looney tunes to me.

I found nothing special about the end affixation for the ribbon. In
fact it's not really mentioned.

The ribbon is slit in the center for part of the distance, most of it actually, claiming to eliminate "breakage" due to stress cracks? If so, then there are substantial forces that are not in the desired plane of operation, it would seem. This is unique, haven't seen that one before...

(...could it be that the edges are being driven and the center has nil flux, so it flaps out of phase??)

The xover, at least on the surface appears to be non-unique and designed to merely adjust for the non flat operation of the ribbon when it is trying to be used over a relatively wide bandwidth. If anything it is fairly simple and non-unique - obviously has to reduce the pass band sensitivity of the ribbon system to "boost" the extremes...

So the only things that seem possible new*ish* are the slit in the ribbon and the "booster magnets". The latter have me scratching my head...

At least in this first fast read this looks like yet another example of the US Patent Office being willing to patent anything pretty much...

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