[chinsettawong]

maybe the plates isolated.
quad 57 treble (squacker + tweeter) using 0.5mm and 1.5kV

the must DIY makers proffer to put the dust filter on headphones
after squashing it like this,
claimed that else it will damage some frequencies

on quad 57 guide it says to put it normally without stretching and some suggest to use some heat-shrink membrane and heat it.


squash like this

I think that humidity makes more sound distortion then dust, you will hear it without any sound from the headphone, the dust cover or some felt layers the only that can protect from it.


if it shorted (on headphones) you will hear really distorted low sound, on speakers I read that if you forget to put the resistor, all the diodes will blow (so DIY headphones to).

Are you sure that the treble panel on Quad 57 has only 0.5 mm gap? I don’t think you can bias 1.5KV with that small gap.

 

[legopart]

Are you sure that the treble panel on Quad 57 has only 0.5 mm gap? I don’t think you can bias 1.5KV with that small gap.

Yes 0.5mm
I have to restore my pair.
*one tweeter having some born parts that I have to fix, working on it now.
the restoring guide describe the distance to 0.5mm.
I tested to prove this, the distance under the border tapes (will not! remove, they important for the distance)
My metal ruler thickness is +-0.5mm so its 0.5mm
don't know the reason for 1.5Kv for 0.5mm maybe because the size (I still not checked this chapters in the book)

the plate separate by crossover to 3 boards 2 squacker (low tweeter) and 1 tweeter, 1.5kV bias, the size is something like 33*66cm.

 

[wrinex]

yeah resonance of the dust cover in combination of the foil resonance creates a new combined resoanance so it should be stretched very lightly. at the same time the dust covers thickness adds up to the membrane thickness. so a 3 micron membrane with 2 3 mincron dust covers behaves more like a 9 micron membrane.

 

[wrinex]

Are you sure that the treble panel on Quad 57 has only 0.5 mm gap? I don’t think you can bias 1.5KV with that small gap.

breakdown of air is around 3 Kv a mm

I think it was a little thicker spacing but, one must not forget that the pcb stator itself has the copper on the outside, so it is 0.5 + thickness of the stator almost. wich makes it possible to use 1.5kv since 1.5 would be the breakdown voltage of the 0.5 gap but there is an extra 0.5-1mm from the stator. if they etched the holes on teh stators it is actually even more, since the breakdown voltage of pcb is much higher then air. By etching the holes the path from copper to foil is even slightly higher then 0.5mm + 1mm+ the edge of the hole where the copper is etched away. total of 1.5-1.6mm witch would give you a breakdown voltage of 4Kv. another thin to keep in mind i believe is you should add the voltage swing of the trannie to. so 1.5Kv bias + the opposite voltage swing on the stator for instance for a headphone max 0.5 Kv or something ? so total of 2kv. i add this value because the stator when pulling on the foil has a opposite charge of the foil bias. it makes it want to jump faster.

and lastly the stuff is coated, wich increases breakdown voltage to. but as you can see in the stator when this paint fails once.... it will keep failing until everyting gets destroyed. although these panels look a bit like the had a bit more troubles then breakdown voltage only overdrivven or the foil came lose. most likely overdrivven since it looks more like the stators arced from one to another witch has far more destructive amperage behind the spark


just my 2 cents

 

[chinsettawong]

I really, really like to see you guys actually try biasing that kind of voltage with the driver having only 0.5 mm spacer. Try it and let us know if it’s actually OK.

I actually give the information of what I have leaned over years of making electrostatic headphones here. Nothing that I put here is something that I haven’t tried. If you don’t like to use the dust cover, that’s fine. It’s all up to you.

 

[quintile]

yeah resonance of the dust cover in combination of the foil resonance creates a new combined resoanance so it should be stretched very lightly. at the same time the dust covers thickness adds up to the membrane thickness. so a 3 micron membrane with 2 3 mincron dust covers behaves more like a 9 micron membrane.

i don’t buy this.

the resonance of the dust cover will be at very low frequency (relatively speaking) as it will be under almost zero tension - it is still crinkled. finger in the air guess, 30hz?

the diaphragm will have a resonance of more like 100 to 500hz depending on material, size and coating.

given the self damping if the crinkled plastic dust coveri would expect this to have a very low Q resonance.

the two frequencies will be far enough apart and differ enough in Q to have very little effect on each other.

could you do some response measurements with and without dust covers?

-Steve

 

[wrinex]

i don’t buy this.

the resonance of the dust cover will be at very low frequency (relatively speaking) as it will be under almost zero tension - it is still crinkled. finger in the air guess, 30hz?

the diaphragm will have a resonance of more like 100 to 500hz depending on material, size and coating.

given the self damping if the crinkled plastic dust coveri would expect this to have a very low Q resonance.

the two frequencies will be far enough apart and differ enough in Q to have very little effect on each other.

could you do some response measurements with and without dust covers?

-Steve

if the main membrane resonance is indeed 100 or 500 hz i am absolutely wrong !! but i cant think of a panel having such high resonance if it has to do fullrange (i thought it was about a headphone). for a tweeter it does not matter indeed since cover has lower res then the frequency the thing is gone produce. only thickness counts in that case.

here a measurement of a stacked ESL adding more membranes, witch is almost the same as adding additional dust covers except they are not active. so the increase in output as seen here is not present of course you can see as well resonance is going up. but im not to sure yet if this is related since these are active.

 

[wrinex]

I really, really like to see you guys actually try biasing that kind of voltage with the driver having only 0.5 mm spacer. Try it and let us know if it’s actually OK.

I actually give the information of what I have leaned over years of making electrostatic headphones here. Nothing that I put here is something that I haven’t tried. If you don’t like to use the dust cover, that’s fine. It’s all up to you.

problem is mostly we are comparing apples with pears.. a headphone has a really low resonance compared to a tweeter like this. the tweeter would not even function without allot tension at high bias voltages since the slightest imperfection in terms of equilibrium would make the foil stick to one of the stators witch result in instant arcing. (because the surface area is much larger it is easy to move the foil close to one stator) As example i got a few mid/top panels from solo sound here that use 1.2 mm stators made from PCB with a normal laquar on the copper side, copper side outwards.

They have a resonance of 350-400hz, and have a spacing of 1 mm stator to membrane. + the 1.2 mm of the pcb(stator) itself so actually 2.2 mm. there bias is a whopping 5Kv+. and step up ratio120! they are only 10x15 cm in size but 4 of them almost give 88-90dB efficiency @ 1 meter, so yes it is possible but it depends on the purpose.. an reliability is an issue when you push it this far as they did. although most panels failed 15 years later... still rather good.

 

[chinsettawong]

I have done a few pairs of ESL myself, and I know very well that making ES loudspeakers and ES headphones is very different. For one thing, the drivers of the headphones are positioned right next to your ears. Even a slightest noise can be annoying. The dust cover is there not only to protect the dust. It also serves as a protective seal against humidity and the possible sweat going inside the drivers. You can try making a pair of headphones and see it for yourself.

Please, can we get back to only headphones discussion here?

 

[qu1en]

I have had issues with resonance with the sweat guard if i dont make it loose enough. I have to be quite purposeful about keeping it loose. Even though the SRF is around 20-30Hz, during deep bass you can hear it rattle, kind of like a buzz if there is even a little bit of tention.

 

[legopart]

Discovered that all the glues are useless, I can break the bound easily.

Hello,
I have 007 which have tiny holes in the membrane, so am planning to renew it.
But I don't know how to separate rings that sandwich the diaphragm.
Any ideas?

This why I learned by hard way not mess with Stax,
After the disassembly you remain with lots of boards that cant stick together again, not remaining the issue of stretching+coating.

 

[afgmjkl]

Discovered that all the glues are useless, I can break the bound easily.



This why I learned by hard way not mess with Stax,
After the disassembly you remain with lots of boards that cant stick together again, not remaining the issue of stretching+coating.

Recent models like 007 are assembled by screws not the glue.

 

[chinsettawong]

Recent models like 007 are assembled by screws not the glue.

Have you already fixed your diaphragm? If the hole is only a tiny one, you don't need to renew it. Use it as it is, and it should be OK.

 

[afgmjkl]

Have you already fixed your diaphragm? If the hole is only a tiny one, you don't need to renew it. Use it as it is, and it should be OK.

There are 0.5mm split and one tiny hole on the diaphragm.
I've removed dusts and solve noise issue, but recently found that it has treble dip around 1.4kHz.
I'm going to recoat the diaphragm but I hear same dip on other headphones, so my left ear may cause this problem.

 

[legopart]

There are 0.5mm split and one tiny hole on the diaphragm.
I've removed dusts and solve noise issue, but recently found that it has treble dip around 1.4kHz.
I'm going to recoat the diaphragm but I hear same dip on other headphones, so my left ear may cause this problem.

Try to re-screw little bit and tight again (don't break the screws) the connectors maybe you created some dis-balance or glue the corners with regular thin selotape only to see if it helps.

do the screchie noises comes after several time of listening or immediately ?