La Folia planar - Bipole radiation - diyAudio
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Old 22nd September 2008, 07:15 PM   #1
jzagaja is offline jzagaja  Poland
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Default La Folia planar - Bipole radiation

Gentleman,

Popular La Folia planar ribbon speaker can be set to dipole or bipole radiation. I couldn't find any thoughts on bipole mode. I mean plastic membrane can be attached to both sides of neo magnets rows so one can connect them as dipole push pull or bipole. The latter behaves like infinite baffle because two membranes are close to each other. Am I right it will make more bass? Do I need tweeter for La Folia?


And one more thing is SPL. My simulation for 10 um thick Mylar and Alu, 60x40cm panel, 0.3T tells me 81dB SPL. Am I right?
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Old 22nd September 2008, 07:30 PM   #2
tinitus is offline tinitus  Europe
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Default Re: La Folia planar - Bipole radiation

Quote:
Originally posted by jzagaja

Am I right it will make more bass?


Not sure you will gain anything but a better impedance...I also have concerns about the small amount of air trapped between the 2 membranes

It may need a bigger box, but then goes the good idea to have both "planars" driven by common set of magnets
I believe the problem with the use of planars fore bass or midbass is the big movement of the membrane

long time ago I build several version of the LaFolia...the best woofer was a true ribbon, only fastened at top and bottom and loose at the sides...man could it move, without any hint of "drumskin effect"
the urge is still there, and now we can get neo magnets I think I would build a "slim" midrange planar and use multiple ordinary woofers fore bass, but expencive....at the moment 2 pairs of tweeter ribbon in the works.
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Old 22nd September 2008, 10:28 PM   #3
jzagaja is offline jzagaja  Poland
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How does the true ribbon woofer looks like? Wide (>15mm) and long true ribbon goes down to 250Hz. By the drum skin effect do you mean frame reflected wave?

I think ESL lovers should know bipole electrostat. Quad 63 has two membranes but it is dipole isn't it?
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Old 22nd September 2008, 10:46 PM   #4
tinitus is offline tinitus  Europe
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Quote:
Originally posted by jzagaja

How does the true ribbon woofer looks like?

Sorry cant show picture, its long gone by now

But I can tell you it was about 500mm wide and 1.2meter long/high...well, a little less wide at the top like Apogee, but if thats important I dont know
There was a tweeter at the side as well, just like Apogee
Membrane was corrugated
You know, when OleTofte made the first LaFolia he simply read the Apogee patent
I also made a version with the membrane fastened at the sides only, using thin foam "surround"...it was good too, but not as sweet in the mids as the "true ribbon" one

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Old 22nd September 2008, 10:56 PM   #5
jzagaja is offline jzagaja  Poland
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Thanks now I know how Alex's omni looks like. He has nice 2um foil.

Well I like omnis. The trick is to delay first reflections as much as possible but I've heard Bang Olufsen Beolab 5 in Struer when they were standing close to the wall. No problem - very good speaker.
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Old 22nd September 2008, 11:07 PM   #6
tinitus is offline tinitus  Europe
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Sorry, I deleted that omni thing

A big version of the raal would probably make a good 2way...implementation of woofers could be problematic though

Advantage would be higher sensitivity and impedance...and MAYBE it could be used a bit lower than a single "standard" ribbon...expencive experiment though

Well, it does look sweet...and then think of one MUCH bigger
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Old 22nd September 2008, 11:14 PM   #7
jzagaja is offline jzagaja  Poland
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I would prefer RAAL head and Bandor 150 in TL with cone reflector and active differential xo (4th order tweeter and second order woofer). Superb look guaranteed. Cost 850$ total, DIY of course
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Old 29th September 2008, 04:49 AM   #8
a.wayne is offline a.wayne  United States
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Quote:
Originally posted by tinitus
Sorry, I deleted that omni thing

A big version of the raal would probably make a good 2way...implementation of woofers could be problematic though

Advantage would be higher sensitivity and impedance...and MAYBE it could be used a bit lower than a single "standard" ribbon...expencive experiment though

Well, it does look sweet...and then think of one MUCH bigger

Tinitus,

Any more pics or info on your "Cylinder " ............


Regards,
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Old 29th September 2008, 11:34 AM   #9
tinitus is offline tinitus  Europe
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Im only daydreaming not really sure if its worth the trouble and money
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Old 29th September 2008, 06:34 PM   #10
a.wayne is offline a.wayne  United States
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Quote:
Originally posted by tinitus
Im only daydreaming not really sure if its worth the trouble and money

Well you know simplicity is not that simple
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