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Old 8th June 2010, 12:35 AM   #1
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Default martin logan daulforce bass

hi all
im starting a project similar to the ml clx which will use 2x er audio esl3 bass panels with a 4mm pacer per speaker and some new ml quest z pannels i have for the mid high i per speaker
they above speakers will be set out in the same cofigeration as the clx

now for the question, the eraudio panels come as 2 seperate 1225mm x 500mm panels and i have 4 of them so i can either use 2x per speaker setup side by side to the mid /high panel same as clx or try using them to make a daulforce setup and mount them behind each other beside the mid / high panel or maybe one firing forward and one firing back or i could even make them the same as the clx so 2x diaphrams and 3x stators joined together

any advice or help regarding the above setup and the ml daulforce system would be uch appreciated

cheers
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Old 8th June 2010, 09:52 AM   #2
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hi all
to simplify my above post

how do i make a bass panel the same as the martin logan daul force

i have all the panels,stators,coating and mylar so i just need to know how to configure them
also do i need special transformers and bias supplies to run the daul force setup

cheers
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Old 8th June 2010, 11:17 PM   #3
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hmmm
80 reads and no answer, surely it cant be that hard its only 3 stators and 2 diaphrams

the strange bit is how are they wired to work together surely this is not beyond the expertese of this forum?

regards sheafer
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Old 8th June 2010, 11:44 PM   #4
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Quote:
Originally Posted by slr 5000 View Post
surely it cant be that hard its only 3 stators and 2 diaphrams

the strange bit is how are they wired to work together surely this is not beyond the expertese of this forum?

regards sheafer
Hello slr 5000,

A 3 stator 2 diaphragm arrangement requires 2 bias supplies and the usual center tapped step-up transformer.

See attached figure taken from patent US3136867:
BRETTELL - Google Patent Search

You can accomplish the same doubling of available force on the diaphragms with 1 bias supply using 4 stators and 2 diaphragms like Sony does in their patent US3941946:
Electrostatic transducer assembly - Google Patent Search

Remember that using the Vbias and transformer from ER, when you configure the panels in the double diaphragm arrangement the diaphragms will move twice as far as they normally do so you will need to adjust the D/S, Vbias, and step-up ratio accordingly.

Another tidbit of information, when you place the two diaphragms near each other separated only by 2*(D/S) the resonant frequency of the double diaphragm system will increase by 15%-20% over the resonant frequency of the panels used as single diaphragm systems. This was a surprise to me when I first tried it.

In my experience, unless you have size(width) constraints or are merely wanting to build a triple stator/double diaphragm arrangement for learning or novelty reasons, you will get better results if you take the same 2 panels and arrange them side by side. My 2 cents...
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Last edited by bolserst; 8th June 2010 at 11:56 PM.
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Old 9th June 2010, 12:36 AM   #5
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thank you kind sir

so it seems that if sound quality is my primary concern then the daul diaphram assembly would be a lot harder to get right and is more to do with keeping the panel size down without affecting bass output than being /sounding better

regarding the resonance frequency , i pressume my aim would be to get this above the working frequency of the panel so lets say my bass panels will be working up to 300hz i would idealy want to have the resonance of the panel above say 500hz ? is this correct

regards sheafer
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Old 9th June 2010, 09:50 PM   #6
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Quote:
Originally Posted by slr 5000 View Post
regarding the resonance frequency , i pressume my aim would be to get this above the working frequency of the panel so lets say my bass panels will be working up to 300hz i would idealy want to have the resonance of the panel above say 500hz ? is this correct
The fundamental resonant frequency of the bass panel sets your low frequency extension.
For example, if you want them to play down to 30Hz, you will need the resonance set at 30 Hz or lower.
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Old 10th June 2010, 12:09 AM   #7
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hi all
is there a way to calculate resonace for a particular panel size and diaphram tension ?

for example bass panel size 1.8m high x 500 mm wide 3.5m mylar .8kg tension

full range panel 1.8m high 300mm wide 3.5m mylar 1kg tension

both the above are something im considering as i already have the perf metal for the stators and mylar
the bass panel would do 300hz down and the full range panel from 300hz up with seperate stepup transformers
i will also have to get the stators powder coated ,is double dip on the powdercoat sufficent for insulation?
spacers will be 3m tape but not sure on thickness ,any advice would be welcome

cheers
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Old 10th June 2010, 03:02 PM   #8
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Quote:
Originally Posted by slr 5000 View Post
hi all
is there a way to calculate resonace for a particular panel size and diaphram tension ?

for example bass panel size 1.8m high x 500 mm wide 3.5m mylar .8kg tension

full range panel 1.8m high 300mm wide 3.5m mylar 1kg tension

both the above are something im considering as i already have the perf metal for the stators and mylar
the bass panel would do 300hz down and the full range panel from 300hz up with seperate stepup transformers
i will also have to get the stators powder coated ,is double dip on the powdercoat sufficent for insulation?
spacers will be 3m tape but not sure on thickness ,any advice would be welcome

cheers
Resonant frequency is not easily calculated. For starters, the mass of the airload on the diaphragm is difficult to quantify.
With rectangular diaphragms that are much longer than they are wide, the resonant frequency is mainly determined by the unsupported width.
For example, doubling or halving the length has little affect on the resonant frequency where as doubling or halving the width does.
Also the stiffness changes(decreases) with increasing bias voltage.
Diaphragm Resonance change with HV bias

You started this thread saying you had some ER Audio bass panels.
Your best chance for success is to take a look at their assembly instructions for recommendations on diaphragm tensions, spacing, and stator coating.
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Old 12th June 2010, 02:58 AM   #9
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hi bolserst

the project above was originally planned with the eraudio panels but the more i think about it the moroe i think i would not be happy with the result as the finnished speakers would end up very wide but only 1200mm tall

all the best sounding esl i see are alot taller ,i also dont want the music to dissapear when standing so i feel that a taller esl would be better

i found some stator material today that seems suitable its 4.8mm hole and 1.6mm thick ,it looks almost identical to the stator material on my martin logan request panels i feel 1mm would be a better thickness though

is standard powdercoat ok for insulation ? i will use 3m tape for spacers as it works well on my ml panels and seems very easy to use
the dimesions will be as mentioned above 1.8m high by 500mm for bass panels and 1.8m x 300mm for mid /high panels they will be mounted side by side in a frame with the mid/high panels

any advice would be great i will start a seperate build thread if any one is interested

regards sheafer
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