[spritzer]

Sure looks like it. That opens up a whole can of worms though...

 

[green0153]

Well there were even closed Koss ESP950 made but they weren't much.
I think nikongod had a pair.

Somebody just has to buy them

 

[edstrelow]

Quote:

Originally Posted by Kabeer /img/forum/go_quote.gif Has anyone seen these Electrostatic headphones? NordicNeuroLab - Making fMRI easy Seem rather interesting .

I sent a query to the US Distributer who mentioned that they do not provide an amplifier as there are already of-the shelf options. Again sounds like Stax.
Certainly the driver specs look like a Lambda.

Evidently someone is re-making these as sealed phones a la the 4070. I wonder if it is Stax or a third party?

Maybe there is some advantage in these medical applications in using non- magnetic drivers. For whatever its worth these are "FDA approved."

They are also working on an earbud system.

 

[Beefy]

Quote:

Originally Posted by edstrelow /img/forum/go_quote.gif Maybe there is some advantage in these medical applications in using non- magnetic drivers. For whatever its worth these are "FDA approved."

No, it probably just means that they went to the effort of having them certified for the application.

Medical device certification is a very difficult but lucrative process.

 

[edstrelow]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif No, it probably just means that they went to the effort of having them certified for the application. Medical device certification is a very difficult but lucrative process.

Since the "M" in "fMRI" refers to magnetic, I suspect that you could have problems placing magnetic drivers inside the magnetic field of an MRI machine. Maybe thats why they went electrostatic.

 

[Beefy]

Fair point.

 

[les_garten]

Quote:

Originally Posted by edstrelow /img/forum/go_quote.gif Since the "M" in "fMRI" refers to magnetic, I suspect that you could have problems placing magnetic drivers inside the magnetic field of an MRI machine. Maybe thats why they went electrostatic.

Those magnets are around 4 Gauss I believe. They will pull anything with iron out of your hands before you enter the MRI ring. I've played with them a bit. VERY impressive magnet!

Are the Stax drivers non Ferrous?

 

[HeadphoneAddict]

Right now they use headphones where the transducer in the another room from the MRI machine's magnets, with long air tubes between transducer and headphones to conduct the sound. They're pretty bad sounding.

 

[Beefy]

Quote:

Originally Posted by les_garten /img/forum/go_quote.gif Are the Stax drivers non Ferrous?

Generally copper or brass, so only magnetic by contamination of the alloy.

 

[Michgelsen]

I saw a modified HE60 for the same purpose in a medical article somewhere a long time ago. It is indeed the magnetic field of the (f)MRI scanner that causes problems with dynamic headphones or anything else with metal in it. The HE60 uses plastic stators IIRC. The magnets are so strong that it can transform a coin for example into a dangerous projectile.
They have closed the 'phones because such a scanner can be as loud as 100dB for the patient. It is both hearing protection, a way for the doctors to communicate with the patient and a way to make the whole procedure less stressful for the patient.

 

[Michgelsen]

Double post.

 

[Kabeer]

I read the Stax SR-3 is 200v, and normal bias phones/amps are 230v.
If I used the SR-3 out of normal bias sockets on say a SRD-7, would it be bad news? (or make it better?) . Little bit confused here.

And re:MRI
Yup thats basically it, you cant use magnets (therefore dynamic cans) in a MRI machine, and the machine is crazy loud so it has to be closed and very isolating.
Stats fit the bill, but supposedly the closed forms (there is a closed ESP950 too) sound poo due to the closed nature where it's originally an open design.

 

[spritzer]

All normal bias cans prior to the 1977 SR-Sigma used a 200V bias and the SRD units had 200V bias supplies. There was no harm in switching to 230V though, it just makes the phones a bit more efficient.

 

[Kabeer]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif All normal bias cans prior to the 1977 SR-Sigma used a 200V bias and the SRD units had 200V bias supplies. There was no harm in switching to 230V though, it just makes the phones a bit more efficient.

Thanks Spritzer, thats cool then, I can use them with an SRD7 later on too

.

 

[KrypticMind]

Just joined Team Stax! I'm blown away by how crystal clear they sound, coming from AD2Ks and a roommate's K702.

On a side note, I think there may be a very slight channel imbalance on my SRM-1/MK2 Pro. I'm pretty sure the problem is not with the Stax as the imbalance appears on both. Is there a way to "fix" this?