[100VoltTube]

I believe it has been brought up before, but I can't seem to find it either. I haven't really looked, though. I'll take a look

 

[chinsettawong]

Hi,
 
What kind of drill bit do you use?  I normally set my router to run at its maximum speed, about 18,000 RPM.  I think I set my drilling speed at 2,400 mm/min.  Drilling has never been a problem.  However, using the same bit for drilling to route, it's not very good.   As you can see, I always stick with 2 mm holes, and I find it's easy to drill and route using the same thing.
 
By the way, my drill bit is very similar to this:
 

 

[quintile]

Hi all.
 
sorry for the thread drift
 
I am not building from new but repairing some Micro seiki ms-2 headphones from the 1970s.
I have done this before with some success though the bass response was limited.
 
I have bought another pair cheaply on ebay and am keen to experiment, reducing the diaphragm tension,
This is hard as the design of the headphone cells increases the tension as they are assembled, but trial and error
will get me there.
 
So, hat adhesive do people recommend for attaching diaphragms to their support rings?
 
I have used UHU POR in the past but this is hard to control being quite thick. I have heard of people using
spray contact adhesive, anyone here had success with that?
 
If so I assume you just spray the support rings and immediately place them on the diaphragm in its stretcher - using
it as normal adhesive rather than contact adhesive?
 
Thanks for any help,
 
-Steve

 

[chinsettawong]

No, don't use spray adhesive. It's not strong enough to hold the diaphragm with tension.

 

[SuperPollito]

This is most impressive that people are able to DIY electrostatic headphones. Keep up the good work everyone!

 

[OnyxOcelot]

 So, hat adhesive do people recommend for attaching diaphragms to their support rings?

 
I think the most commonly recommended adhesive in this thread -- and the one that I have used successfully -- is Contact Cement.  I use Dap Weldwood Contact Cement, seen here, but there may well be other brands selling a similar product depending on your location.  AFAIK, this (and more commonly, the much less pungent water-based version) is the product most commonly used in cabinet shops to adhere laminate and veneer to cabinetry, so it should hold strong for a long time.  I apply the contact cement to the spacer and immediately place the spacer on the stretched mylar.  I don't wait for the contact cement to dry as one might, if you were applying the glue to both surfaces, as in cabinet making or wallpapering.

 

[100VoltTube]

I realize that a topic of much discussion is diaphragm tension, specifically measuring and repeating it. An idea I had for measuring it is tapping it and measuring the frequency. You can easily calculate the tension based on resonant frequency and the stretcher dimensions. I don't specifically know the formula, but it should be something like: diameter*tension=pitch, for circular hoops. I'm not sure about rectangular stretchers.

 

[chinsettawong]

Unless you are going to do a production run, I don't think the repeatability issue matters that much.

 

[100VoltTube]

Repeatibility probably wasn't the best choice of words. I meant being able to repeat others' tension levels.

 

[wppk]

hello there
I know what I am going to talk about is not really DIY for the making of electrostatic headphones, but I think that this could interest some of you, and mending is part of the subjetc. so I have bought very rare bisset DD45e headphones. said to be, on the net, OEM from stax, and the fact that it doesn't need an energiser puzzled me enough to get it. Also, I find them quite beautiful, and I am fond of rarities, as one can read on other posts from mine. the headphone came with a strong imbalance, so, I dicided to try to repair it. It is really weird that it can work without any energiser, nor electronic elements to make it work inside. I leave picture here, for you to see.
a first approch of the mending didn't bring anything, so I thought that maybe, the diaphragm needed to be coated at new. So I used the electrostatic liquid I used for stax mendings before, but then, I got no more sound at all... I should put a new mylar, but I would get to the permanent and usual problem of the stretching, I guess.
does anyone have an idea of how this can work ? and also, on how to mend it ? does enyone have headphones like that, damaged on one side too, from whom I could by a driver ?
when both ways still worked, and when I balanced it ( the imbalance was important, needed one quarter of the balance knob course to the left ), I really liked the sound ! It is really a stax quality sound, even if the bass is not as deep as with lambdas or 007. Very very pleasant on the mids and highs.
does anyone have an experience with these ?
thanks
Luc
pictures : amazing to see how it looks like brand new.

 

[chinsettawong]

Hi Luc,

The headphones look awesome. But are you sure that they're electrostatic? If there is no bias supply, the headphones could be electrate electret.
Have you opened up both sides yet? Do you not see any small step up transformer in there at all?

 

[wppk]

Hi chinsettawong
yes I am sure. well, this is written on the box and the headphones. Yes, I have open both sides, there is no step up transformer at all. ithe plug a stereo normal jack, so it seems it is not electrate .
I will send photos in a minute of the box and closer to the "electrostatique" writing on the can ( the box is in french)

 

[wppk]

 

 

[wppk]

the trademark says BST but it is not the bst we all know, seemingly, if I read well about them.
its a shortway for Bisset.

 

[wppk]

and below the yellow fabric, there is nothing electronic. just the structure of the can.