Tnx!
Here I have started gluing the spacers (20x2mm PVC) :
Using diluted contact cement - smells ....
/R
Here I have started gluing the spacers (20x2mm PVC) :
Using diluted contact cement - smells ....
/R
The project is a bit on hold - have to do some glue tests !
I've got hold of epoxy used for gluing planes and want to se how well it bonds to Mylar.
I have contact cement that works fine, but then I only have abt. 0.2s to get the stators aligned right!
All stators are now paited och have 3-layers of polyester or laquer on them.
Have some more PVC-spacers to glue, but after that it's time for the Mylar and a first smoke test!
/R
I've got hold of epoxy used for gluing planes and want to se how well it bonds to Mylar.
I have contact cement that works fine, but then I only have abt. 0.2s to get the stators aligned right!
All stators are now paited och have 3-layers of polyester or laquer on them.
Have some more PVC-spacers to glue, but after that it's time for the Mylar and a first smoke test!
/R
I would be interested in seeing if possible , Info on how you plan to do your power supply and x-over if any ....
regards,
regards,
I have built a couple of test EHTs.
One using a 555 timer and then a 4-5x voltage multiplier and one using standard traformers and multiplierstages.
Will post pictures when I have a final version!
The PVC is from a local dealer. Comes in 1000x2000mm sheets.
I have cut it into strips 20 & 10mm wide.
Using 2mm for the treble panels and 1.5mm for the tweeter ( no 1mm in stock)
Have not decided how I will construct the X-over yet, but I think it will be active!
/R
One using a 555 timer and then a 4-5x voltage multiplier and one using standard traformers and multiplierstages.
Will post pictures when I have a final version!
The PVC is from a local dealer. Comes in 1000x2000mm sheets.
I have cut it into strips 20 & 10mm wide.
Using 2mm for the treble panels and 1.5mm for the tweeter ( no 1mm in stock)
Have not decided how I will construct the X-over yet, but I think it will be active!
/R
Hi,
don't you think the spacers are a bit to wide,
because 20mm all around the speaker is a lot
of capacity which does not make any sound,
but is seen from the amplifier so: wasted efficiency.
For your tweeter I would cut them in halves.
Regards
Frank
don't you think the spacers are a bit to wide,
because 20mm all around the speaker is a lot
of capacity which does not make any sound,
but is seen from the amplifier so: wasted efficiency.
For your tweeter I would cut them in halves.
Regards
Frank
Hi Frank,
The choice of 20mm wide spacers came from:
1. Trying to cut 1000x10mm strips resulted in uneven strips as the plastic moved in the gigant metal sheet cutter. Even with 20mm strips I have to stand on the sheet while a helper cuts the plastic. A saw could be used instead but cutting was so much easier.
2. Using 5mm aluminum tape for the "EHT-loop" results in two 7.5mm strips for gluing the Mylar to the spacers => higher tensioning possible.
3. With the intended frame, I'll "wedge" the panels in slots and the width off the spacers is needed for stability.
/R
The choice of 20mm wide spacers came from:
1. Trying to cut 1000x10mm strips resulted in uneven strips as the plastic moved in the gigant metal sheet cutter. Even with 20mm strips I have to stand on the sheet while a helper cuts the plastic. A saw could be used instead but cutting was so much easier.
2. Using 5mm aluminum tape for the "EHT-loop" results in two 7.5mm strips for gluing the Mylar to the spacers => higher tensioning possible.
3. With the intended frame, I'll "wedge" the panels in slots and the width off the spacers is needed for stability.
/R
Anyway at least you are doing some real things,
it seems that most members here are only discussing it.
I wish you succes and good luck for your projekt,
and if you have done everything all right, you will be
very surprised!
Regards
Frank
it seems that most members here are only discussing it.
I wish you succes and good luck for your projekt,
and if you have done everything all right, you will be
very surprised!
Regards
Frank
Update:
PVC strips will not be used as spacers! 😡
Glued a midpanel yesterday evening using contact cement. Everything stuck together as suposed but it it so much easier using tape and it bonds better to both the film and stators.
Got a midpanel( 200x1000mm) working, using 1mm tape & 5µm Mylar. F0 is ~250Hz and it measures good up to abt. 17.5kHz where my sound card starts to drop off!
/R
PVC strips will not be used as spacers! 😡
Glued a midpanel yesterday evening using contact cement. Everything stuck together as suposed but it it so much easier using tape and it bonds better to both the film and stators.
Got a midpanel( 200x1000mm) working, using 1mm tape & 5µm Mylar. F0 is ~250Hz and it measures good up to abt. 17.5kHz where my sound card starts to drop off!
/R
Got my "large" panel working last night.
400x1000mm, 2mm foam spacers, 5µm Mylar, 3.25kV bias
Measured f0 ~70Hz and the panel is usable to abt. 7.5kHz where I hope my tweeterpanel will take over!
/R
400x1000mm, 2mm foam spacers, 5µm Mylar, 3.25kV bias
Measured f0 ~70Hz and the panel is usable to abt. 7.5kHz where I hope my tweeterpanel will take over!
/R
-Finaly, all panels are done! 🙂
Tweeter panel under test:
NowI have to get them to play together.
Any sugestions on a sutible x-over ? ( 150Hz & 7kHz)
/R
Tweeter panel under test:
NowI have to get them to play together.
Any sugestions on a sutible x-over ? ( 150Hz & 7kHz)
/R
Very nice job!
If I may suggest, it would be convenient to have an active crossover (like a cheap Behringer) so you can dial in the crossover frequency, slopes and panel attenuation quickly. Just to find out what is needed exactly.
If you use one step-up transformer per panel you can attenuate with the winding ratio's and use the transformer properties as part of the filter. Together with a couple of resistors and capacitors this should make a nice crossover.
If I may suggest, it would be convenient to have an active crossover (like a cheap Behringer) so you can dial in the crossover frequency, slopes and panel attenuation quickly. Just to find out what is needed exactly.
If you use one step-up transformer per panel you can attenuate with the winding ratio's and use the transformer properties as part of the filter. Together with a couple of resistors and capacitors this should make a nice crossover.
Tnx!
I would like to keep the filter passive for now, but a active x-over is absolutely in the future plans!
Got a tip on a Swedish forum to look at how Quad solved the xo issue. So I'll try some simple RC-filters this evening! 🙂
Running tests I'm using 2x small 100V PA transformers, but will wind new toroids when I have a frame made for testing both panels.
/R
I would like to keep the filter passive for now, but a active x-over is absolutely in the future plans!
Got a tip on a Swedish forum to look at how Quad solved the xo issue. So I'll try some simple RC-filters this evening! 🙂
Running tests I'm using 2x small 100V PA transformers, but will wind new toroids when I have a frame made for testing both panels.
/R
Measurement is done using Tombstone, DIY mic and a DIY amp.
Mic is placed near the panel ( abt. 20-30cm) and the panel is sweapt from 20Hz to 20kHz.
Not scientific, I know, but it points me in the right direction! 🙂
/R
Mic is placed near the panel ( abt. 20-30cm) and the panel is sweapt from 20Hz to 20kHz.
Not scientific, I know, but it points me in the right direction! 🙂
/R
It looks really nice. 
How does it sound?
Will you be using two different transformers for the big and small panels?
Wachara C.
How does it sound?
Will you be using two different transformers for the big and small panels?
Wachara C.
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