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GeSo 22nd August 2008 09:11 PM

Geert - Hybrid ESL
 
Hello All I am new to this forum.
I ordered the books by Sangers and Wagner. I have been reading tons of sites while I wait for the books to arrive. I am very impressed with Geert Vij..... design and build.
I am interested in building a 5.1 surround system, 1 pair of hybrids for the front and for the center and surround just the panels if possible.

I understand why ESL's need to be away from the wall prferably 15" - 24". How are Magnepan and Final able to design wall mount panels? I would prefer that my surrounds are off the floor and preferably wall mounted if at all possible.

On one of the sites that I read (HTForum.nl) under d'underground? I believe there is a diagram with dimensions etc of Geert's build but I can no longer find it online. Does anyone know what the cut out is for the nail section and nail spacing?

Does the center channel have to be the same size as the front's to have the same frequency output, minus the cone driver of course.

I have also read that some builders uses perforated metal with different hole sizes to optimize full range performance. For example larger holes for the lower frequencies and smaller holes for the mid / high. With that said can that same therory be used with the wire stator? Using wider spacing for the lower frequency's and closer spacing for the mid / highs?

Calvin 23rd August 2008 11:12 AM

Hi,

You know....sometimes a working link or a pic can be very helpful. :rolleyes: Uncompleted names aren´t familiar to everyone.

The only idea of how to place a panel close to a wall that appears to me is to use reflectors on the backside of the panel to reflect the sound sideways. Without any waveguiding apparatu´ it´d simply sound terrible (to me the finals are very short of sounding terrible anyway.....but thats only personal taste)

I´m not into HT, but from what I know the sound of the centre channel should be the same as the main channel´s (though I would rather omit the centre channel at all and invest more into good main channel speakers). The problem with most panels now is, that they are intended to be used with the longest dimnsion in the vertical direction.
This will probabely disclude the use as centre channel. Alternatively the panel might be turned horizontally, but then it should be a large panel to accomodate for two or more listeners. I don´t know of any commercial product at the moment that features such a large panel.
Curving the panel might be a solution, but there is no high quality centre of this kind around.

I don´t know any good reason to use different hole sizes, especially not with larger holes for the bass and smaller ones for the midhighs.
The other way round would be correct efficiencywise! Smaller holes for the bass and larger holes for midhigh (but that would introduce other disadvantages). So the best solution is to use just one hole size with small holes. The same holds true for wire stators. Thinner wires with close spacing to each other for increased efficiency.


jauu
Calvin

gvy 23rd August 2008 03:47 PM

Hi Geso

I think, that I am Geert Vij.... ;)
I have build "d'ondergrondse" , my home theatre including the ESL's and subs about 1,5 year ago.
The description of the building process of the complete theatre (in dutch) can be found here

http://www.htforum.nl/yabbse/index.php?topic=47163.0

page 15-20 handle about the esl's

or here for just the ESL's
http://www.zelfbouwaudio.nl/forum/viewtopic.php?t=3917

On the foto , you can see the system.
I do not use a center .
I do use 2 subs, and they are placed on the best acoustical location ( mid of the long walls, on the right and left of the listening place)

http://img76.imageshack.us/img76/979...rondse1qa9.jpg

greets
Geert

GeSo 23rd August 2008 10:42 PM

I wasn't sure if I could post link and or pic since I am a new member. Figured a quick Google search would suffice.

The gents’ name that I am referring to is Geert Vijncke one of the links I have found of his build is http://www.zelfbouwaudio.nl/forum/viewtopic.php?t=3917

I have not listen to Final's but have and very much enjoy the sound of the Magnepan's.

So mounting them against the wall is not an option, understood.
After the front and rear channels are built I will determine if a center is needed. My next question is wire spacing; I believe Sanders recommends 10 wires per inch I have also read 15-20/inch. Does this all relate to the diameter of the wire? I have access to 24awg kynar wire. What would be the optimal spacing for such wire?

GeSo 23rd August 2008 10:43 PM

Hello Geert and thanks for the reply,

Since I am new here my posts take a pit to show up on the site.

I am wondering if you have a CAD layout of your build? I am curious to know the HxWxD and spacing of the nail area. I have plans to build a SonoSub using a Shiva driver from www.DIYcable.com. I might as well use the same technique for the hybrid as well. I currently have a pair of Dayton Audio aluminum drivers from here.

http://www.partsexpress.com/pe/pshow...number=295-335

Wondering if this would be comparable to the drivers you are using? Last question for now is how do you think your surrounds would sound if they were raised off the floor a bit without the help of the driver? I know they will not go into the low frequencies. I forgot where I read this but I thought there is a frequency cut off sent to the rear chanels? Thanks for now.

Calvin 25th August 2008 09:40 AM

Hi,

mounting the panel close to a wall without any reflecting/waveguiding device is no option.
You must assure that the ´reflected soundwaves´ are not passing the membrane. So a reflector with a triangular shape behind the panel might be the solution. (it won´t be as good as a freely positioned panel, but it should work sufficiently).

When designing a panel I start with thinking about a catalogue of goals.
a) what is the freq-range the panel should work over? -->Bandwidth of the panel should be ~1-2 octaves more.
b) what size is possible --> always use the largest dimensions for highest dynamics
c) what d/s is needed --> depending on the lower bandwidth limit and size of the panel´s segments --> use the smallest d/s possible
d) decide what stator material and concept You want to use
e) decide which type and dimension of materials you need
f) check about availability of materials and the possibilities of manufacture
g)....
h).... etc etc.

jauu
Calvin

gvy 25th August 2008 09:12 PM

Hi GeSo,

It is all in the dutch description :
Some dimensions:


panels outer dimensions : h = 1240mm x w = 250mm
membrane free moving dimensions : h = 1160mm x w = 170mm

wire incl isolation : diam = 1 mm (24AWG wirewrap)
there are 72 wires next each other
acoustical opening = 55% : ( 45%= wirewidth, 55%= opening)

wire-membrane distance = 1,5 mm ( used spacer material = PS plastic , polystyreen 2.5mm) 2.5mm(spacer) - 1mm(wirediam) = 1.5mm

Geert

GeSo 4th September 2008 06:15 AM

Full range panels
 
I have read the armature should not attempt to build a full range panel for their first project. After reading Wagner's book, reviewing The Audio Circuit site and going over Geert build I am confident that I can build a full range panel. The question is sound quality, electronics and efficiency. Mind you this is going to be for a home theater. The stator size I was thinking about would be 10” x 60” for the front channel and 10” x 30” for the rear, 12 wires per inch 30awg Kynar wire. I plan on using 3M tape for both the spacer and glue. For the diaphragm I was thinking about ordering DuPont Mylar. My goal is to try and cover as much of the audible range as possible, with the subwoofer handling the lower tones. I am clueless when it comes to the electronics. Which ratio would go best with my panels and who should I buy them from? I am also stuck on the coating as well.

FYI, the build process for the panels will be identical to the way Geert built his.

Calvin 4th September 2008 08:54 AM

Hi,

please do Yourself a favour and listen to the ol´chaps and build a hybrid first. Wagner´s FR and most of the projects from the audio circuit leave a lot to be desired, especially regarding dynamics and the demands of HT. The chances to build a good midhigh-panel with the first shot are low already. The panel will work of course -hey, nothing is easier to build than a ESL that puts out ´some sounds´.
It could be a revealing experience and it could even be that the panel outperforms everything you have listened to yet...but it won´t be a really good panel. The best panels of today are soo much superior to any dynamic driver that not just a few listeners doubt their ears on first contact!
It´d be rather the beginning of a long journey with increasing capabilities of the panels the more you´ve built.
Beginners are usually overwhelmed when they first listen to a ESL-panel even when it is a rather bad one. And usually Beginners make serious failores within the building process.
The most common failures are:
- trying to build a FR-panel
- low resonance Fs
- ignoring efficiency issues
- thinking of beeing able to do better by doing different (Why the *** did he do that? It looks soo weird, so I think I´ll better do it different)
The results are panels with horrible frequency response, abnormally low efficiency --> crappy dynamics...and low instability treshold.

Since You intend to use the panels for HT you need panels that can put out serious levels of SPL. This can only be achieved with small d/s and large membrane areas. For a Hybrid working from ~200Hz on upwards dimensions of 10"x50" and 1/25" (d/s) will give good results (my panels of this size reach a stunning 110dB@4m with app 50W of input power with exceptional low values of distortion).
But don´t expect to get anything useful below 200Hz! Add a proper dynamic bass here. A wire stator won´t reach the high levels of dynamics like a sheet metal stator, but with the recommended dimensions You could expect more than 100dB@4m without the need of excessive drive power.

With such a tall and thin panel as You suggested phase cancellation must be corrected for below 800Hz(!). The level of equalization becomes so high below 200Hz, that this alone kills everything what is needed for good sound, dynamics and HT-usage. This is a problem every open baffle system faces, regardless of its dimensions. The only thing that ´saves the day´ is the huge high-Q bass resonance.
But -and it is a very big BUT- this is a one note bass featuring a high Q-factor, hence a soft sounding bass with low precision and a serious suckout in the upper bass region. Nothing one would accept with a dynamic bass, especially since this goes with thin and anaemic sounding vocals.
You would have to correct for the high Q and need considerable equing too. All of which kills output and dynamic headroom, especially when executed passively (it costed the old ML Sequel roughly 10dB of output and efficiency and this was crossed over at >250Hz!!). Staying above 200Hz eases the effort You have to put into the crossover too. A simple 2nd order Highpass (2 components) and a parallel Notch (needs 2 or 3 components) may be all You need. Without the possibility and knowledge(!) to measure the speaker´s behaviour it´ll be impossible to equalize a FR-panel.

A FR-ESL that could meet the dynamic requirements of HT needed to be much wider than Your panels...40" or more. Besides much reduced demands in building and greatly reduced size a hybrid-ESL would still reach better results with regards to sonics, dynamics and drive requirements.

jauu
Calvin

GeSo 5th September 2008 01:57 AM

Thank you Calvin,

I do not think I can build ESL’s better nor am I trying to reinvent the wheel here. My goal is to have panels that sound good and that are aesthetically pleasing. If I must go hybrid then I will. All four panels will be 10”x50”, what specs should I looks for with the driver? I noticed the NSS 0.3a uses a 7” woofer, as stated above I have a pair of Dayton 7” woofer. That can be found here http://www.partsexpress.com/pe/psho...tnumber=295-335 will this be ok? I imagine it should be fine since I am going to us a subwoofer as well.

Now that we agree that I am building a hybrid system can I have some advice on electronics? What size transformer bias supply, crossover etc would you suggest and from where? I am also having difficulty finding coating and diaphragm material in the states. Can anybody help with this?


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