[chinsettawong]

The “fart” is actually the sound of the diaphragm hitting one of the stators. Since the diaphragm is sitting in the middle of the two stators with only 0.5 mm of clearance on each side, any sudden change in pressure in the headphone’s enclosure can push the diaphragm to hit one of the stators. If the tension is high enough, after hitting the stator, the diaphragm bounces back to the middle where it should be. If the diaphragm tension isn’t strong enough, the diaphragm can stuck on the stator and would only bounce back when you discharge it.

As far as I have experienced, Stax headphones’ diaphragms are tension high enough and the diaphragms bounce back. This phenomenon is quite common no matter they’re DIY or commercial headphones and it should not do any harm.

 

[statfi]

The “fart” is actually the sound of the diaphragm hitting one of the stators. Since the diaphragm is sitting in the middle of the two stators with only 0.5 mm of clearance on each side, any sudden change in pressure in the headphone’s enclosure can push the diaphragm to hit one of the stators. If the tension is high enough, after hitting the stator, the diaphragm bounces back to the middle where it should be. If the diaphragm tension isn’t strong enough, the diaphragm can stuck on the stator and would only bounce back when you discharge it.

As far as I have experienced, Stax headphones’ diaphragms are tension high enough and the diaphragms bounce back. This phenomenon is quite common no matter they’re DIY or commercial headphones and it should not do any harm.

Thanks!
I am working my way through this great thread from the beginning. Most impressive, chinsettawong.
But, in the meantime: The SR-009 has polymer enveloping the stators, inside the protective screens. Are you also enveloping the transducer in protective, acoustically (almost) transparent polymer? If so, what material and how thick? If not, why not? I had imagined it was necessary to prevent arcing.

 

[chinsettawong]

Yes, it's very important to have protective screens protecting the driver from dust that might go into the driver. I'm not sure what material it is that Stax uses. But for us, DIYers, we normally use the same material as our diaphragm material. That's Mylar. The most popular thicknesses are 3 microns and below. Please read through the thread and you'll find all the answers that you might have.

 

[statfi]

...Please read through the thread and you'll find all the answers that you might have.

Thx! Just after I posted the query, I hit your relevant previous post. I will read on.

 

[statfi]

The simplicity of F=Eq, the fundamental equation for electrostatic headphones, is a thing of beauty. E is the signal voltage between the stators divided by their distance, and Q is the charge on the diaphragm and F is the force moving the diaphragm. However, some of the beautiful simplicity fades away *if the Q is not fixed in time and space* wrt. the diaphragm. So the question is:

Does anyone know how much the charge on the diaphragms moves around laterally on the diaphragm as the musical voltage is applied to move the diaphragms axially, either from an empirical or theoretical point of view?

 

[chinsettawong]

The charge on the diaphragm should remain constant at all times, IMO.

 

[statfi]

The charge on the diaphragm should remain constant at all times, IMO.

Exactly. *Should*. But does it?

 

[chinsettawong]

I’m sure it does.

That’s the whole point of coating the diaphragm with high resistance coating.

 

[statfi]

I am going to be away from the www for a while. Is there a way to download the content of this thread so I can read it without being connected?

 

[WallofHooligans]

Heyo head-fiers in this thread. I could use some info that I haven't seen anywhere in this thread.
Specifically I'm looking for a way to build a custom self biasing adapter. I understand how to do that, but I don't understand how to choose a transformer for the job. I know that the design uses a 1:60 ratio between the primary and secondary, as well as a voltage cascade to multiply the voltage further. I don't understand the values I should be looking for or building. I don't understand how to choose a trafo that would be okay being plugged into a 15-60watt amplifier for example.
I've poked around inside a few adapters and found the lack of documentation as to the specs of the transformers concerning. As an example, what would I be looking for if I wanted to replace the transformers in a stax srd 6/7SB? Any rules of thumb to know?

 

[federicopol]

Hello everyone, i'm here for some help, if possible: long story short: i finished my phones but they have a problem:

The efficiency seems really low: the volume even cranking my amplifier (the stax base model) at max the volume is very low and i notice distorsion when there are highly dynamic passages.

I think there could be two causes but i'm unsure of my line of thinking:

1- bad coating product: the product i'm using (floor cleaner) could be less than ideal.

2- cable: i'm using cat5 cable because that is what i have around. Only one strand per pole. I think the cable could be undersized for the application.

I don't know what else to think, i'm tending towards the cable but i am not sure... Could someone more experienced chime in and give me some advice? Thank you.

By the way here is a photo of the finished headband/earpads. Really minimal but really comfortable and light even with the driver mounted in.

 

[quintile]

i would expect the coating.
measuring it is hard, as most multimeters dont read upnto 1Gohm.

from memory (i am on holiday) you are liiking for about 1gohm measured between two coins dropoed on the conductive surface if the diaphram.

cat5 cable is thick enough (the current is very low), the capacitance of the twisted pairs, and the insulation resistance is probably not up to 600v. probably ok for now but long term you should find somthing better.

-Steve

 

[bui501-tech]

i would expect the coating.
measuring it is hard, as most multimeters dont read upnto 1Gohm.

from memory (i am on holiday) you are liiking for about 1gohm measured between two coins dropoed on the conductive surface if the diaphram.

cat5 cable is thick enough (the current is very low), the capacitance of the twisted pairs, and the insulation resistance is probably not up to 600v. probably ok for now but long term you should find somthing better.

-Steve

Steve has a good point re. the capacitance of the cat5 cable. there's a reason why Stax and Koss and Sennheiser all use flat cables with parallel conductors for their electrostatic headphones. Cat5 cable has twisted pairs that are all intertwined with each other inside the sheathing.
If you're experimenting/starting out, I'd at least try with flat ribbon cable rather than cat5 to at least eliminate one likely issue.
If you want to go better than the flat ribbon (computer connection type) cable, Koss sells extension cables for their electrostatic headphones for $20 for a 10-foot piece -- I just cut off the ends and use the actual cable. Very flexible and relatively durable -- and they were designed for electrostatic headphones.

 

[federicopol]

Thank you very much for your answers.

I can't buy koss cable: i'm in the eu probably the shipping is gonna kill the convenience...

For now i'm going to buy some computer flat cable next week and find a multimeter that can read high resistance.so i can verify the coating.

Thanks

 

[chinsettawong]

Hi,

I would like to know exactly what spacer thickness you are using as it’s one of the most important factors that affect the efficiency. Most of us here use 0.5 mm.

Wachara C.