[arnaud]

From seeing the picture of the deteriorated foam in the lambda above, I wouldn't bother replacing it. Acoustically, this kind of foam has virtually no effect (it has such large pores), even in 2-3mm thickness.

My guess is that this was there to act like a filter against large debris, but probably not so much for its damping properties.

 

[shipsupt]

When I checked the back foam on my LNS (that didn't look that bad from the outside) I found that they were on the verge of disintegration and turning to a black dust.  I removed them to keep from creating a mess.  

 

[spritzer]

Quote:

@spritzer : do you build a KGSSHV ?

 
Not for order or anything like that. 
 
Quote:

The one hermetically sealed electrostat I can think of is the old Dayton-Wright.  They filled the transducers with SF6 gas to make use of its' higher breakdown voltage (than air) and increase the efficiency of the panels.  14 kV bias supply

 
Those were crazy but I think the new Sound Lab's are at 14kV now with teflon wire stators. 

 

[yawg]

Quote:

The foam is not the same as the dust cover and does not protect against it. The drivers are protected by a thin plastic film on the outside of the drivers to protect against dust. Storing the phones in a plastic bag as additional protection doesn't hurt and may help, so I do that.

In my case (LNS) it seems that the foam held the drivers in place. When I exchanged my worn earpads for new leather ones I noticed that the foam had partly disappeared and the drivers moved around quite freely. Actually I can move them by shaking the cans.

 

[Warpkitty]

Two part question:
 
Can anyone tell me what the output impedance of a Stax amplifier is? Any Stax amp is fine I just want to get an idea. The only thing I've seen that has this spec is the Mal Valve Three which is apparently 600 ohms.
 
Also, does it make sense to use the same electrical principles of output/input impedance when discussing electrostatic headphones compared to dynamic headphones? Given the 1k Ohm+ load I would think things like electrical damping wouldn't come into play here.
 
Me all mixed up?

 

[telecaster]

Damping and headphones membrane is snake oil. Insignificant frequency variance is all you get with high amp out impedance.

 

[davidsh]

Quote:

Damping and headphones membrane is snake oil. Insignificant frequency variance is all you get with high amp out impedance.

You sure? How big do you think the factor should be for it to become an actual issue? And how's the impedance varying with frequency in most electrostats?

 

[MDR30]

A quick question: is it possible to replace the protective membrane of the SR5 driver with cling film or similar?

 

[telecaster]

Quote:

You sure? How big do you think the factor should be for it to become an actual issue? And how's the impedance varying with frequency in most electrostats?

It's my opinion, other will disagree. There is no issue appart from falsy believing the bad and the ugly. From experience it is pure snake oïl to sell you their Wonder amplifier, so sadly typical in audio industry.

 

[davidsh]

Quote:

It's my opinion, other will disagree. The factor should be zero. From experience it is pure snake oïl to sell you their Wonder amplifier, so sadly typical in audio industry.

I'm just thinking about what factor is acceptable. For example if you use a inline resistor adapter with a low impedance headphone on something like a speaker amp, you would probably get a very bad found, if say the factor is 10. 

 

[arnaud]

As far as I understand:
1. Damping factor for electro-dynamic transducers is very real, its effect measurable.
2. A stat phone is basically a capacitor (115picoF or so for stat models?), the impedance increases with frequency and is mostly reactive (like any cap).
3. There is parasitive inductance, capacitance and resistance in the cable, don't remember which dominates for but it may be capacitance, hence the special attention paid to spacing the lines.
4. Similar to damping factor for an electro-dynamic amp, the output capacitance of the estat amplifier (or lack of to be precise) is important to ensure the amplification isn't load dependent. In this case, I assume the goal is that the amp output capacitance must be much lower than the mainly capacitive load it is driving in order to have load independent transfer characteristics.

 

[kevin gilmore]

impedance DECREASES with increasing frequency
 
All stax made amplifiers have 5.1k safety resistors in the output lines. So even if the output impedance
of the amplifier was zero, the output impedance would still be 5.1k. This is to protect the headphones
from arc damage.
 
Yes you can replace the outer filters with thin stretched film.

 

[DefQon]

Quote:

A quick question: is it possible to replace the protective membrane of the SR5 driver with cling film or similar?

Food wrap bag which is made out of pvc same as the dust film membrane Stax uses which is just a bit more thinner. 

 

[arnaud]

impedance DECREASES with increasing frequency

Thank you! Obviously I was going to blow this one up, I ought to stay way from E.E field

So reminder of the capacitor impedance: 1/(j*C*Omega), with C the capacitance value, j the complex notation suggesting this is a reactive load, and omega being 2*Pi*frequency.

Hoping I didn't butcher this one either

 

[telecaster]

Quote:

As far as I understand:
1. Damping factor for electro-dynamic transducers is very real, its effect measurable.
 

All you can measure is the frequency response difference, not the real damping of the membrane.