[Djarum]

Hi Folks,
 
Got a bit of a problem with my O2 mki, and I've done some quick looking around for potential solutions, but I was hoping to see if anyone had any advice on what to do next. They have a serious channel imbalance (have to turn up the left knob 3 ticks for every 2 ticks on the right knob), and I think the left phone is distorting at high volumes. The problem is definitely in the phones (or cable) since it has the channel imbalance on multiple amps, and other phones don't have a channel imbalance on the amps I've run it on.
 
I've tried leaving them on for a week, and discharging the bias on both phones, but that hasn't fixed the problem. In fact, when I try to discharge the bias, I either hear little or no pop in the left phone.
 
This pair has had a channel imbalance before, but it went away after time. This new imbalance has lasted for a couple of months now, though. Could it still be a parasitic charge after all this time, or it is more likely to be a tear? I have run over the cable with my chair before, so could it be a problem with the cable?
 
Sorry for all the question, but I do so love my O2s. I finally got a KGSS to have a complete static rig, then two weeks later the phones go. D'oh!

 
Thanks in advance for any advice anyone can give,
Djarum

 

[Michgelsen]

I'm not mixing those two voltages up. I was responding to deadlylover, who said that the diaphragm may become the negative pole when the voltage on the stators is higher than the bias voltage on the diaphragm. He said 'funky stuff may start happening'. I don't know where he(/she?) bases this on. It's not that positive poles pull harder on the negative poles than the other way around. The both do the same work, so I don't see why it would make a difference.
Although now that I think of it, it could have the same reason why some capacitors have polarity (http://en.wikipedia.org/wiki/Electrolytic_capacitor#Polarity). Electrostatic (ear)speakers are a form of a capacitor. To clarify, this could only be a problem if you play so loud that you effectively change the polarity, and would have nothing to do with the specified bias voltage of the headphones: thus 'real' normal bias 'phones would also be affected.
 
Perhaps if you read my post again now that I've made it clearer it makes more sense. I was in a hurry when I was typing it, sorry.
 
When the bias voltage is lower, the efficiency of the 'phones is lower and therefore you need to turn up the volume somewhat. That's all the practical information for the needs of a normal user. There is no harm in using pro bias earspeakers with the normal bias output, only maybe if you play excessively loud, which is never a good idea.

 

[spritzer]

Ok, stuff like this is why I'm writing articles about electrostatics.  The only thing the bias does is to set the sensitivity of the system.  The bias voltage has to be matched to the drive voltages and the diaphragm-stator gap for ultimate performance and so that the drivers don't suffer from arcing but if it is lower then stators "grip" on the diaphragm is diminished.  No way in hell that this will damage the drivers in any way. 

 

[Shike]

Thanks spritzer, that's what I was thinking which made me "What" at the manual.  Either way I've ordered a SRD-7 Pro bias from the person that sold me the SR-202's.  If I like the sound I'll keep them if not I'll sell them as a bundle probably.
 
Quote:

Ok, stuff like this is why I'm writing articles about electrostatics.  The only thing the bias does is to set the sensitivity of the system.  The bias voltage has to be matched to the drive voltages and the diaphragm-stator gap for ultimate performance and so that the drivers don't suffer from arcing but if it is lower then stators "grip" on the diaphragm is diminished.  No way in hell that this will damage the drivers in any way. 

 

[Amarphael]

I think i also have this problem, albeit very sligthly, with the right channel. It's more noticeable with the KGSS than the SRM-717. I guess it woudn't hurt to open them up and go over the cable conections with some contact cleaner.
 
Quote:

Hi Folks,
 
Got a bit of a problem with my O2 mki, and I've done some quick looking around for potential solutions, but I was hoping to see if anyone had any advice on what to do next. They have a serious channel imbalance (have to turn up the left knob 3 ticks for every 2 ticks on the right knob), and I think the left phone is distorting at high volumes. The problem is definitely in the phones (or cable) since it has the channel imbalance on multiple amps, and other phones don't have a channel imbalance on the amps I've run it on.
 
I've tried leaving them on for a week, and discharging the bias on both phones, but that hasn't fixed the problem. In fact, when I try to discharge the bias, I either hear little or no pop in the left phone.
 
This pair has had a channel imbalance before, but it went away after time. This new imbalance has lasted for a couple of months now, though. Could it still be a parasitic charge after all this time, or it is more likely to be a tear? I have run over the cable with my chair before, so could it be a problem with the cable?
 
Sorry for all the question, but I do so love my O2s. I finally got a KGSS to have a complete static rig, then two weeks later the phones go. D'oh!

 
Thanks in advance for any advice anyone can give,
Djarum

 

[svyr]

Ok, stuff like this is why I'm writing articles about electrostatics.  The only thing the bias does is to set the sensitivity of the system.  The bias voltage has to be matched to the drive voltages and the diaphragm-stator gap for ultimate performance and so that the drivers don't suffer from arcing but if it is lower then stators "grip" on the diaphragm is diminished.  No way in hell that this will damage the drivers in any way. 

=) thank you spritzer. I see we've spammed you out of hiding using the 'somebody on the internet is wrong' method
(c) xkcd

 

[Michgelsen]

What's the reason for a positive bias voltage? Wouldn't a negative voltage also work?
 
Quote:

Ok, stuff like this is why I'm writing articles about electrostatics.  The only thing the bias does is to set the sensitivity of the system.  The bias voltage has to be matched to the drive voltages and the diaphragm-stator gap for ultimate performance and so that the drivers don't suffer from arcing but if it is lower then stators "grip" on the diaphragm is diminished.  No way in hell that this will damage the drivers in any way. 

 

[chinsettawong]

Bias voltage can be either positive or negative. 
 
Wachara C.
 
Quote:

What's the reason for a positive bias voltage? Wouldn't a negative voltage also work?
 
Quote:

Ok, stuff like this is why I'm writing articles about electrostatics.  The only thing the bias does is to set the sensitivity of the system.  The bias voltage has to be matched to the drive voltages and the diaphragm-stator gap for ultimate performance and so that the drivers don't suffer from arcing but if it is lower then stators "grip" on the diaphragm is diminished.  No way in hell that this will damage the drivers in any way. 

 

 

[Region2]

Quote:

Quote:

Ok, stuff like this is why I'm writing articles about electrostatics.  The only thing the bias does is to set the sensitivity of the system.  The bias voltage has to be matched to the drive voltages and the diaphragm-stator gap for ultimate performance and so that the drivers don't suffer from arcing but if it is lower then stators "grip" on the diaphragm is diminished.  No way in hell that this will damage the drivers in any way. 

=) thank you spritzer. I see we've spammed you out of hiding using the 'somebody on the internet is wrong' method
(c) xkcd

LOL!  Though I've seen this strip before, the context made my morning 

 

[bobkatz]

Of course a negative bias voltage would work. But the absolute polarity of the signal to the ears would be reversed.
 
BK

 

[spritzer]

Both + and - bias can and has been used but the issue here is dust.  Most of it is + charged (around 80% or so) so the + bias will repel it. 

 

[BoilermakerFan]

Most household dust is negatively charged (70%+ according to the majority of reputable HVAC filter manufactures).  That is why the electrostatic filters on HVAC systems use positively charged elements to attract and capture the household dust.
 
However, dust from human skin and hair, as well as fibers from other animals is positively charged:
 
http://www.siliconfareast.com/tribo_series.htm
 
So the main question is whether your household dust is a bigger concern for your headphones when they are not being used than the dust from your body when the headphones are on your head.
 
Roger Sanders switched his commercial electrostatic speakers from positive bias to negative bias years ago because he found dust was the biggest issue for warranty claims.  As houses have more and more synthetic materials and more synthetic clothes are worn, the percentage of negatively charged dust in the air is increasing. 
 
The ideal solution would probably be to maintain the positive bias in the amp, but have a lower level negative bias supply available on the headphone storage rack.  It would be a PITA to have to discharge and cancel the bias charge every time you switch from listening to storage and back again, but it would mitigate dust issues as much as possible.  I'm not sure if it would have minimal or significant impact to the driver's long term durability. 

 

[les_garten]

Quote:

Most household dust is negatively charged (70%+ according to the majority of reputable HVAC filter manufactures).  That is why the electrostatic filters on HVAC systems use positively charged elements to attract and capture the household dust.
 
However, dust from human skin and hair, as well as fibers from other animals is positively charged:
 
http://www.siliconfareast.com/tribo_series.htm
 
So the main question is whether your household dust is a bigger concern for your headphones when they are not being used than the dust from your body when the headphones are on your head.
 
Roger Sanders switched his commercial electrostatic speakers from positive bias to negative bias years ago because he found dust was the biggest issue for warranty claims.  As houses have more and more synthetic materials and more synthetic clothes are worn, the percentage of negatively charged dust in the air is increasing. 
 
The ideal solution would probably be to maintain the positive bias in the amp, but have a lower level negative bias supply available on the headphone storage rack.  It would be a PITA to have to discharge and cancel the bias charge every time you switch from listening to storage and back again, but it would mitigate dust issues as much as possible.  I'm not sure if it would have minimal or significant impact to the driver's long term durability. 

Hey,
    What was the end result of your Custom ear molds for your Stax?

 

[BoilermakerFan]

Quote:

Hey,
    What was the end result of your Custom ear molds for your Stax?

The first pair proved it is feasible and worthy of further pursuit.  I'm scheduled for a second ear impression next week.  The issue was the way Starky molded the tips.  They pulled the driver too far out of the ear and made it flush or parallel to the side of my head instead of following the straight, angled line of sight down the ear canal.  They were trying to hide or stealth the tip.  That bend caused the midrange to be recessed and it was a little wonky too.  So now we're going to actually insert the 001 driver into the molding material and set the proper angles in the ear impression before shipping those to Starky for round two.  I'm confident they'll be dialed in, even if it takes 3 or 4 passes to mail it down, but for the money I spent, I expect perfect tips. 

 

[les_garten]

Thanx fpr the Update!
 
I have some 003s and am very interested in how this shakes out.   I've been using ear molds since 1989 for various things so am used to them quite a bit.  I have one from Averysound on my Jawbone BT headset and it is awesome.  I definitely am down for a Stax Ear mold.