[Claus-DK]

well the head line says it all.....

I just got a pair of act-9000 on ebay and they are electret.......

What am I to expect from theese phones...

Will update when they arrive

 

[spritzer]

Electrets use a special plastic film to provide the polarizing charge needed so no external bias supply is needed like with electrostatics. The electret material can be either on the diaphragm or the stators (depends on the design) but they can't be compared to full blown electrostatic on performance though some come pretty close.

 

[Faust2D]

Quote:

Originally Posted by Claus-DK /img/forum/go_quote.gif well the head line says it all..... I just got a pair of act-9000 on ebay and they are electret....... What am I to expect from theese phones... Will update when they arrive

What are these act-9000 headphones? Do you have pics?

 

[spritzer]

ATH-9000

 

[Faust2D]

Ah, ATH-9000. Got it.

 

[Claus-DK]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif Electrets use a special plastic film to provide the polarizing charge needed so no external bias supply is needed like with electrostatics. The electret material can be either on the diaphragm or the stators (depends on the design) but they can't be compared to full blown electrostatic on performance though some come pretty close.

Is the ATH-9000 then an electrostatic ??
they do have this special box, does that not deliver that bias supply you mentioned ??

 

[E.B.M.Head]

Electrets can loose the charge and then they don't work properly anymore. I think it's the case with my Unipolar. I know they are very picky about the amp, but I doubt that a wrongly amped can can sound this crap.

 

[spritzer]

Quote:

Originally Posted by Claus-DK /img/forum/go_quote.gif Is the ATH-9000 then an electrostatic ?? they do have this special box, does that not deliver that bias supply you mentioned ??

No they are not electrostatic. Electrets just like electrostatics need high voltage on the stators to make the diaphragm move so the adapter box only contains the transformers to step up the voltage.

 

[Claus-DK]

Thanks for the info...

OT I just looked at your profile and all I can say is WOW..

 

[spritzer]

Quote:

Originally Posted by Claus-DK /img/forum/go_quote.gif Thanks for the info... OT I just looked at your profile and all I can say is WOW..

I've had a few planar headphones over the years...

 

[krmathis]

I did not know that Audio Technica made electret headphones in the past.
Let us know what you think of them when they arrive though.

 

[spritzer]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif I did not know that Audio Technica made electret headphones in the past. Let us know what you think of them when they arrive though.

They made plenty of them though I bet all of the drivers were outsourced.

 

[IceClass]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif They made plenty of them though I bet all of the drivers were outsourced.

Hmmm...interesting.
Care to advance a theory as to who the manufacturer might have been?

 

[scompton]

The ATH-7, ATH-8, etc sure look like imitation SR-30s. I think they sound pretty good. I'd love to hear the ATH-9000. I'd also like to hear the Sonys. From what I've read, they're probably what Spritzer is referring to as near stat performance. They've been talked up so much though that they go for a lot of money the few times they come up.

 

[Faust2D]

Quote:

Originally Posted by scompton /img/forum/go_quote.gif The ATH-7, ATH-8, etc sure look like imitation SR-30s. I think they sound pretty good. I'd love to hear the ATH-9000. I'd also like to hear the Sonys. From what I've read, they're probably what Spritzer is referring to as near stat performance. They've been talked up so much though that they go for a lot of money the few times they come up.

ATH-8 (Signet TK33) is pretty advanced, more advanced than SR-30. ATH-8 were bipolar back electrets with 2 micron mylar diaphragm. Also SR-30 is from 1982 abd ATH-8 is from form 1978 so I am not sure who imitated who. I had SR-40 and they did not sounds as good as my TK33 (ATH-8). Never heard other electrets, so I don't know what the deal is there.