Hi
Yes I think your questions are useful in getting to
te heart of this wave-bending design. As I said I want
to build and measure one full size and maybe treated paper
is the key or going to some of the more exotic materials that
the later units from the original designer use. The Linaeums
originally had silk but the Radio Shack version used mylar. I was
myself thinking of Kodak Estar type base material as it is dimensionally stable and if made thin enough might be a good choice. The flat bobbin used in the French design does seem a bit heavy but the neo magnets are very strong.
Hope someone out there has time and patience to experiment. I have a feeling the idea is very simple but the devil is in the detail!
Good Luck
AnthonyPT
http://www.6moons.com/industryfeatures/aero/aero.html
Yes I think your questions are useful in getting to
te heart of this wave-bending design. As I said I want
to build and measure one full size and maybe treated paper
is the key or going to some of the more exotic materials that
the later units from the original designer use. The Linaeums
originally had silk but the Radio Shack version used mylar. I was
myself thinking of Kodak Estar type base material as it is dimensionally stable and if made thin enough might be a good choice. The flat bobbin used in the French design does seem a bit heavy but the neo magnets are very strong.
Hope someone out there has time and patience to experiment. I have a feeling the idea is very simple but the devil is in the detail!
Good Luck
AnthonyPT
http://www.6moons.com/industryfeatures/aero/aero.html
Re: Silk Screen material...
I investigated a bit and found that FR4 for the whole diagraph is propably ok for midrange but not for high frequencies since it´s far too stiff and thick having resonances there.
So let´s go for paper on silk. Silk is not as expensive as you might think. Much cheaper than magnets. Still having pretty ideal properties. Also be fabric with less potential for any kind of resonances as James told.
I´ll try to combine ideas with Linaeum and Aero in my DIY design. There is a good document:
US2005152575:
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US2005152575&F=0
I investigated a bit and found that FR4 for the whole diagraph is propably ok for midrange but not for high frequencies since it´s far too stiff and thick having resonances there.
So let´s go for paper on silk. Silk is not as expensive as you might think. Much cheaper than magnets. Still having pretty ideal properties. Also be fabric with less potential for any kind of resonances as James told.
I´ll try to combine ideas with Linaeum and Aero in my DIY design. There is a good document:
US2005152575:
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US2005152575&F=0
There is one thing that can be a problem with Aero -type of designs:
Aero is a closed box. Therefore moving membrane generates a lot of pressure inside. Pressure difference tries to push air back and forth above and below the membrane where is small gaps. The amount of needed air is the same than moved by the membrane.
There are two options:
1) Even if this gap is thin the foils is even thinner, I quess. Therefore gaps have small resistance for air movement and air velocity can be huge causing a lot of side effects like distortion.
Or...
2) Internal volume of the box don´t practically change at all! The pressure difference push the whole foil reshaping it so that volume keeps almost constant. This might cause, what said about the design, that sound velocity in the membrane is the same than in the air. Not really but foil can act like this because pressure changes it´s shape.
Is there anybody who can answer which of these two takes place?
Aero is a closed box. Therefore moving membrane generates a lot of pressure inside. Pressure difference tries to push air back and forth above and below the membrane where is small gaps. The amount of needed air is the same than moved by the membrane.
There are two options:
1) Even if this gap is thin the foils is even thinner, I quess. Therefore gaps have small resistance for air movement and air velocity can be huge causing a lot of side effects like distortion.
Or...
2) Internal volume of the box don´t practically change at all! The pressure difference push the whole foil reshaping it so that volume keeps almost constant. This might cause, what said about the design, that sound velocity in the membrane is the same than in the air. Not really but foil can act like this because pressure changes it´s shape.
Is there anybody who can answer which of these two takes place?
Okay... I speak too much. But this one is important.
There is a FREE open source CAE Linux live-DVD that has everything needed to simulate aero -type of designs and how membrane act. Resonances, radiation pattern, frequency response, ... If you only can make a realistic model and have enough computing power.
http://www.caelinux.com/
If anybody can build such models please share. I'll try and now be quiet for a while.
There is a FREE open source CAE Linux live-DVD that has everything needed to simulate aero -type of designs and how membrane act. Resonances, radiation pattern, frequency response, ... If you only can make a realistic model and have enough computing power.
http://www.caelinux.com/
If anybody can build such models please share. I'll try and now be quiet for a while.
Hi,
Just came across the 6moons article
about the French Wave-Bender design that
started this thread. Seems Audio Consulting
has packaged the unit complete with a brass
plaque in a duo form for a mere 15000 Euros
Hope the designer Francois Diminiare benefits
and I still wonder how Paul Pattock has not
hit hard with patent rights or has the Linaeum
finally gone beyond 19 years of age-))
The magnet costs for the projects do add up but
even the singles will sell for a mere 9000Euros.
I estimated that DIY making a Hp82 (original post)
would cost about $AUD1200 a pair with everything.
So lets see if they can sell them and make them consistant
as that is the trick with Linnys to make them consistant.
http://www.6moons.com/industryfeatures/rubanoide/rubanoide.html
Regards
AnthonyPT
Just came across the 6moons article
about the French Wave-Bender design that
started this thread. Seems Audio Consulting
has packaged the unit complete with a brass
plaque in a duo form for a mere 15000 Euros
Hope the designer Francois Diminiare benefits
and I still wonder how Paul Pattock has not
hit hard with patent rights or has the Linaeum
finally gone beyond 19 years of age
-))The magnet costs for the projects do add up but
even the singles will sell for a mere 9000Euros.
I estimated that DIY making a Hp82 (original post)
would cost about $AUD1200 a pair with everything.
So lets see if they can sell them and make them consistant
as that is the trick with Linnys to make them consistant.
http://www.6moons.com/industryfeatures/rubanoide/rubanoide.html
Regards
AnthonyPT
...also they describe the radiation as bipolar. This implies that the front and rear waves are in phase. I don't see how this can be correct, since the whole assembly, driven by wires in a central magnetic field, moves just like a speaker cone or ribbon.
Very tempting to try and build one though, just for kicks.
Ed
Very tempting to try and build one though, just for kicks.
Ed
Hi
I talked to Serge at Audio Consulting and
to the original designer in France and Audio
Consulting (AC) have the exclusive rights.
Serge at AC was very courteous about it all.
Unless they have doubled the number of magnets and
have two frames I feel the bipole thing is
a misprint or smoke and mirrors to discourage
experimenters. Handling those pesky strong
neo magnets and finding a reasonable price from a supplier
is the trick. The flat circuit board which
in french called the "bobbin" could be
improved from the original and made lighter.
I thinks some of us have got the original plans
from the French site a year or two ago.Serge
did mention a partial kit but that is not cheap
either. As to the amps in those wooden boxes they
look like a lot of cascaded 5w Ic amps or something
somehow integrating them and taming any offset with
their silver wire transformers. Like the 6 moons article
on the Phy-HP guy (did you see his CD player Box)
Audio Consulting also march to a different drum to most of us.
Would be nice to hear those giant Linnys some day. They say
the best Lineaums used doped silk in their membranes.
Regards
AnthonyPT
I talked to Serge at Audio Consulting and
to the original designer in France and Audio
Consulting (AC) have the exclusive rights.
Serge at AC was very courteous about it all.
Unless they have doubled the number of magnets and
have two frames I feel the bipole thing is
a misprint or smoke and mirrors to discourage
experimenters. Handling those pesky strong
neo magnets and finding a reasonable price from a supplier
is the trick. The flat circuit board which
in french called the "bobbin" could be
improved from the original and made lighter.
I thinks some of us have got the original plans
from the French site a year or two ago.Serge
did mention a partial kit but that is not cheap
either. As to the amps in those wooden boxes they
look like a lot of cascaded 5w Ic amps or something
somehow integrating them and taming any offset with
their silver wire transformers. Like the 6 moons article
on the Phy-HP guy (did you see his CD player Box)
Audio Consulting also march to a different drum to most of us.
Would be nice to hear those giant Linnys some day. They say
the best Lineaums used doped silk in their membranes.
Regards
AnthonyPT
Thank Anthony, that's interesting.
Perhaps I sounded over critical in my posts earlier - really a knee jerk reaction to the prices mentioned.
The approach to design is really an interesting one. The key physics lies in two areas, in my mind.
1 - How the coupling of impulse energy from the "bobbin" to the curved diaphragm is controlled.
2- Edge termination of the diaphragm to absorb the "unused" wave.
I think with regard to 1, it is the curvature in the diaphragm that plays a big part in the effectiveness of the design over a large range of frequency. There perhaps a gradual, controlled variation in the effective driven area vs frequency.
It would seem to me that there is ample room for experimentation to influence the factors above. e.g. to implement damping, Diapphragm size and curvature, and perhaps even a diapragm designed with graded stiffness. Easy to talk about - less easy to try especially with long arrays of powerful magnets!
Ed
Perhaps I sounded over critical in my posts earlier - really a knee jerk reaction to the prices mentioned.
The approach to design is really an interesting one. The key physics lies in two areas, in my mind.
1 - How the coupling of impulse energy from the "bobbin" to the curved diaphragm is controlled.
2- Edge termination of the diaphragm to absorb the "unused" wave.
I think with regard to 1, it is the curvature in the diaphragm that plays a big part in the effectiveness of the design over a large range of frequency. There perhaps a gradual, controlled variation in the effective driven area vs frequency.
It would seem to me that there is ample room for experimentation to influence the factors above. e.g. to implement damping, Diapphragm size and curvature, and perhaps even a diapragm designed with graded stiffness. Easy to talk about - less easy to try
especially with long arrays of powerful magnets!Ed
Ed Holland said:
I have tried similar things and they sure were not hifi.
Resonances must be killed before this sounds better. It means a lot of work, tuning and doing waterfall plot measurements.This problem could be solved like done with transmission line speakers. They tune acoustic impedance seen by speaker element. This same could be done for speaker membrane´s surface wave acoustic impedance.
How...
Make the paper diamond shaped so the further you go from the voice coil the narrower it gets. Attach some damping material on the paper or even use soft rubber instead of paper. As an option you could even roll the paper and make spiral
Should work somehow even if adding damping mass or using soft materials doesn´t sound good solution for high frequencies.
Interesting stuff APi,
There are several ideas that spring to mind for improvement of this concept. I'm sure we are thinking along similar lines.
It seems we have two threads running in parallel here - as the "Rubanoide Project" thread is covering the same stuff. Should we request that they are combined?
I posted in the other thread last week, regarding a "ghetto" version of this transducer. Construction was purely for kicks, though results were interesting. I'd like more time to play with this idea, and some test kit to evaluate the results.
Cheers,
Ed
There are several ideas that spring to mind for improvement of this concept. I'm sure we are thinking along similar lines.
It seems we have two threads running in parallel here - as the "Rubanoide Project" thread is covering the same stuff. Should we request that they are combined?
I posted in the other thread last week, regarding a "ghetto" version of this transducer. Construction was purely for kicks, though results were interesting. I'd like more time to play with this idea, and some test kit to evaluate the results.
Cheers,
Ed
APi said:
Or some traditional craftmanship. Recently I bought some Lokta paper. I couldn´t use it for my application, but I found it has far better damping than industrially produced paper. Washi might work as well, but is a lot more expensive.
http://cgi.ebay.de/5-Boegen-handges...8040091QQihZ011QQcategoryZ78367QQcmdZViewItem
http://cgi.ebay.com/HANDMADE-LOKTA-...eZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem
The Lokta in US ebay doesn´t look so good. This looks better:
http://cgi.ebay.de/Japanese-yuzen-w...ryZ37578QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.de/Japanese-yuzen-w...ryZ37578QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Silk only in name...
Silk was what was originally used for screen printing. Commercial silk screen material today is all made from 100% polyester. That said I don't know if sik is more hydroscopic than paper. Tweeters and midrange domes are made out of silk fabric still today.
It would seem that in a design such as this internal loss in the diaphragm material is important. The Linaeum drivers use thin plastic foil which as far as I can tell seems to do a far better job than I would have expected (have owned a number of these). The plastic is quite soft and limp I do not think that it is polyester.
Silk was what was originally used for screen printing. Commercial silk screen material today is all made from 100% polyester. That said I don't know if sik is more hydroscopic than paper. Tweeters and midrange domes are made out of silk fabric still today.
It would seem that in a design such as this internal loss in the diaphragm material is important. The Linaeum drivers use thin plastic foil which as far as I can tell seems to do a far better job than I would have expected (have owned a number of these). The plastic is quite soft and limp I do not think that it is polyester.