omnidirectional ESL
I am currently working on dynamic omnidirectional speakers. I am using fullrangers with a treble-dominated frequency response looking to the ceiling and no reflector. I made the experience that for the superior spatial image is essential to have the drivers on the level of my ears. My conclusion is that the most important point about omnidiredtionals is coherence of the direct part of the signal, not the fact that they show so much indirect reflections.
So I believe for a cylindrical ESL it is better to have many segments that are relatively narrow. A membrane with less tension may probably allow to manufacture this construction in one piece.
A good omni is worth any effort!
Greets, Oliver
Hello everybody! The talk about cylindrical ESLs in other threads lead me to this discussion about mylar thickness.Calvin said:
I am currently working on dynamic omnidirectional speakers. I am using fullrangers with a treble-dominated frequency response looking to the ceiling and no reflector. I made the experience that for the superior spatial image is essential to have the drivers on the level of my ears. My conclusion is that the most important point about omnidiredtionals is coherence of the direct part of the signal, not the fact that they show so much indirect reflections.
So I believe for a cylindrical ESL it is better to have many segments that are relatively narrow. A membrane with less tension may probably allow to manufacture this construction in one piece.
A good omni is worth any effort!
Greets, Oliver
Hi el'ol,
segmenting the cylinder has two disadvantages.
1. if you really want to come close to a cylinder you need to arrange a lot of small cells, which will suffer from a high frequency resonance. e.g.
a cell having 2" width will show a resonance @ about 400-800 Hz, even with low tension.
2. Cells which are angled to each other will show the venetian blind effect, which lead to significant interferences of higher frequencies, causing a lot of ripple in response. Could be that the omnidirectionality is ditributing those effects.
since 10 years the cylinder-ESL is in my mind . Maybe igonna try it. I am sure that the imaging will be breathtaking.
capaciti
segmenting the cylinder has two disadvantages.
1. if you really want to come close to a cylinder you need to arrange a lot of small cells, which will suffer from a high frequency resonance. e.g.
a cell having 2" width will show a resonance @ about 400-800 Hz, even with low tension.
2. Cells which are angled to each other will show the venetian blind effect, which lead to significant interferences of higher frequencies, causing a lot of ripple in response. Could be that the omnidirectionality is ditributing those effects.
since 10 years the cylinder-ESL is in my mind . Maybe igonna try it. I am sure that the imaging will be breathtaking.
capaciti
hi folks,
regarding membran material, there is a new material called teonex, which is considered to outperfrom mylar.
Look here :
www.dupontteijinfilms.com/Teonex/Brochure/2.htm
Hi Calvin,
i read your post regarding your curvilinear panel. It would be interesting to see some frequency response measurements depending on the off-axis angle. I expect it to be very homogeneous between -10 and +10 °, with an significant loss of level @ larger angles.
my segmented panels are designed the same way. I intentionally try to have a good dispersion within +/10 °,which reduces at larger angles. imo too much dispersion is worse, since the first wave energy is reduced and wall reflexions are increased. As long you have sufficient dispersion in between the speakers base witdh, its OK. There is no need for further dispersion.
capaciti
regarding membran material, there is a new material called teonex, which is considered to outperfrom mylar.
Look here :
www.dupontteijinfilms.com/Teonex/Brochure/2.htm
Hi Calvin,
i read your post regarding your curvilinear panel. It would be interesting to see some frequency response measurements depending on the off-axis angle. I expect it to be very homogeneous between -10 and +10 °, with an significant loss of level @ larger angles.
my segmented panels are designed the same way. I intentionally try to have a good dispersion within +/10 °,which reduces at larger angles. imo too much dispersion is worse, since the first wave energy is reduced and wall reflexions are increased. As long you have sufficient dispersion in between the speakers base witdh, its OK. There is no need for further dispersion.
capaciti
From what I've read, segmented cylindrical panels will tend to suffer from a "venitian blind" effect. This makes sense when you consider how strongly traditional panels beam... especially in the high frequency. It would be difficult to get around this affect.
What angles were you looking to offset each segment?
-Wes
What angles were you looking to offset each segment?
-Wes
Hi,
even with 2 of my curved panels placed side-by-side togeteher I can clearly hear and measure the venetian blind effect. With an array of flat panels it should be even more distinct. That leaves You with the problem of producing a truely 360° circular. How´s about a elliptical shape with two curved panels facing each other? The panels could be connected and the space between them be sealed by frame that holds both panels. The sound pattern would be changed from a dipolar cylindrical shape to a bipolar one. The ´cabinet´ could provide for some damping mechanisms as suggested earlier.
Still, I doubt that it´ll be possible to handle the reflection problem with the backside sound waves sufficiently. The lower the freqs the bigger the prob.
While a unidirectional speaker has its merits and friends, there are a lot of people -me included- who prefer a highly directive sound pattern. A cylindrical sound pattern is imo the best for a lot of rooms, because the nasty early reflections from the rooms sidewalls, ceiling and ground are minimized, thereby emphasizig on precize location of soundstage and fine dynamics (resolution of details). Of course is this concept less good for occasional istening, but on the other hand industry provides us with cheap dynamic speakers for ceiling or inwall use for this application
A second advantage is the the more constant soundpressure over distance than with global patterns.
jauu
Calvin
even with 2 of my curved panels placed side-by-side togeteher I can clearly hear and measure the venetian blind effect. With an array of flat panels it should be even more distinct. That leaves You with the problem of producing a truely 360° circular. How´s about a elliptical shape with two curved panels facing each other? The panels could be connected and the space between them be sealed by frame that holds both panels. The sound pattern would be changed from a dipolar cylindrical shape to a bipolar one. The ´cabinet´ could provide for some damping mechanisms as suggested earlier.
Still, I doubt that it´ll be possible to handle the reflection problem with the backside sound waves sufficiently. The lower the freqs the bigger the prob.
While a unidirectional speaker has its merits and friends, there are a lot of people -me included- who prefer a highly directive sound pattern. A cylindrical sound pattern is imo the best for a lot of rooms, because the nasty early reflections from the rooms sidewalls, ceiling and ground are minimized, thereby emphasizig on precize location of soundstage and fine dynamics (resolution of details). Of course is this concept less good for occasional istening, but on the other hand industry provides us with cheap dynamic speakers for ceiling or inwall use for this application
A second advantage is the the more constant soundpressure over distance than with global patterns.jauu
Calvin
wrl said:
J thought about twelve 50mm segments.
Here are the frequency responses of a 50mm fullranger at 0 and 30°. Beaming doesn`t seem to be a big problem at that size. The problem that remains is to find a material with far less tension than mylar. I considered a nylon/latex compound in an other thread but I have strong doubts about linearity.
http://www.ejjordan.co.uk/drivers/jx53.html
Hi el' ol,
you cannot compare directivity of the 50mm jordan to that of a 50mm ESL-stripe. The jordan's effective sound radiating diameter decreases with higher frequencies, while a ESL-membran do not.
A 50mm ESL-stripe will start to roll-off at about 2000 Hz and should have a level drop of more than 20dB at 20000Hz (30° angled).
capaciti
you cannot compare directivity of the 50mm jordan to that of a 50mm ESL-stripe. The jordan's effective sound radiating diameter decreases with higher frequencies, while a ESL-membran do not.
A 50mm ESL-stripe will start to roll-off at about 2000 Hz and should have a level drop of more than 20dB at 20000Hz (30° angled).
capaciti
3M Double Sided Foam Tape
Hey guys,
Regarding the previous discussions on the double sided tape, I just got a nice roll (3M, 1/16" thick, 109' X 1/2") off ebay for a really good price. Here's the link if anyone else is interested.
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=5643987138&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1
Thought I'd post since it isnt easy to come by especially at that price.
Hey guys,
Regarding the previous discussions on the double sided tape, I just got a nice roll (3M, 1/16" thick, 109' X 1/2") off ebay for a really good price. Here's the link if anyone else is interested.
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=5643987138&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1
Thought I'd post since it isnt easy to come by especially at that price.
Further up this thread you list a new film "teonex". In the range you're talking they
have 12.7µm down to 1.5µm! Also I see the same manufacturer makes "Type C Mylar" also 12.7µm - 1.5µm! Type C is what Roger Sanders always advised to get but lamented that you could not buy below 12.7µm...But how to get in small amount?
Lucius
.
Hi lucius,
there is no need for "C" quality. C is just a calibrated type with lower tolerance on thickness, but standard is not worse.
You can either use "Mylar" or the german brand "Hostaphan". its the same material.
Take a look at
www.shackman.de.
They sell Hostaphan in 3,5 and 6 and 8µm thickness. In ebay they offer the material for "high-end" pricing. Contact them directly and deal it out.
If you won't be successful you can contact me at
info@capaciti.de
regards,capaciti
there is no need for "C" quality. C is just a calibrated type with lower tolerance on thickness, but standard is not worse.
You can either use "Mylar" or the german brand "Hostaphan". its the same material.
Take a look at
www.shackman.de.
They sell Hostaphan in 3,5 and 6 and 8µm thickness. In ebay they offer the material for "high-end" pricing. Contact them directly and deal it out.
If you won't be successful you can contact me at
info@capaciti.de
regards,capaciti
After i have made my ESL panel , i noticed that some parts of it play considerably loader than others , especially in higher freqencies. Is it a problem of non-uniform coating ? I use graphite.
Also i have found a very interesting HV switching supply.
It is used for luminescence lamps.
It uses 12 V at input and can be adjusted from 180 to 800V.
Costs only 15 Litas(~5 EUR).
Lukas
Also i have found a very interesting HV switching supply.
It is used for luminescence lamps.
It uses 12 V at input and can be adjusted from 180 to 800V.
Costs only 15 Litas(~5 EUR).
Lukas
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.