Rare vintage electrostatic headphones

[spritzer]

The aim of the thread is to consolidate all the info that is out there of old and frankly strange electrostatic headphones we come across.  I really should have started one of these back in 2005 when I started my collecting but hindsight and all that...    So I'll start off with one so rare that there is pretty much no info out there for this set.  Here is what it looked like when I got it:

 

 

These were made by Audiotec in France and aside from some brochures back in the say we know nothing about them.  There isn't even a model number on them or a left-right identifier.  They are quite big, roughtly the same size as the SR-Omega and the back of the fork is pretty much a clone of the SR-1,2 and 3 setup Stax used. 

 

 

Here are the earcups opened and these do have the honor of having a truly unique earcup design.  No screws as they use nails which are friction fitted.  Very secure assembly but an utter pain in the ass to disassemble... 

 

Not sure what is up with that baffle.  It made of the same material as really old PCB's but those traces don't go anywhere. 

 

 

Driver lifter out of its cradle and doesn't this look familiar.  Turns out that it's the same or very similar driver to the ones used in the Stax electret models.  Never seen one with the mineral wool damping pad being a part of the driver housing though. 

 

 

Same pic but showing a bit more of the green wool pad used on the back of the driver.  This keeps the driver in place against the baffle similar to the Magnavox sets but it's a far from ideal setup.  There is also very little to keep the back wave from colliding with the front and that foam around the driver is decomposing quickly. 

 

 

Showing the connections inside the cups.  The joints simply have fiberglass insulation pushed over them but not secured in any way.  Yet another thing that needs to be fixed... 

 

 

Here is the original 6 pin DIN connector.  Oxidized all to hell so I simply removed it. 

 

Now the important bit, how do they sound.  Well I don't have the original adapters so I had to make due with what I have at hand...    I knew that the stock transformers used with the Audiotec stuff had very high stepup ratio (1:65) so it was no surprise that the highly modified SRM-007tII didn't manage to drive these even at full volume.  I do have a few KGSSHV's here and they did a stellar job with a very balance sound signature.  The bass is a bit odd given the housing and all the colorations it adds but not bad at all. 

 

Finally here is how they look now but I'll do some further mods to them.  They really need a new cable and some baffle insulation...

 

 

Last but certainly not least, great thanks to Luc for giving me this set to play with.   

[mypasswordis]

First thing I thought when I saw the driver was it looks like a Stax electret, so is it an electret or full electrostatic? Looks very cool. Too bad I'm done with collecting vintage 'stats after I find a Gamma Pro and ESP9.

 

Here are the pics of the Superexen I already sent to you:

 

 

PEP-81

 

https://www.dropbox.com/s/4kso86ao196v3yr/IMG_20140113_221339.jpg

https://www.dropbox.com/s/urt7iycl6orzegq/IMG_20140117_224116.jpg

 

EP-5

 

https://www.dropbox.com/s/zib1xq32ynjv41x/IMG_20140113_221434.jpg

https://www.dropbox.com/s/0dz5ebtns5p6rb4/IMG_20140117_222908.jpg

https://www.dropbox.com/s/ujis7j066vt0bre/IMG_20140117_223110.jpg

Edited February 7, 2014 by mypasswordis

[spritzer]

They are electrets but Audiotec also made full blown electrostatics as I've seen the schematic for the energizer.  Bias is -300VDC...

[mypasswordis]

Wow, all kinds of crazy designs back in the day... and bias at -300V potentially means finally a headphone that does not use a modified Stax driver (that isn't Koss/Beyer/Sennheiser/Sony)? Would be very interesting if that were the case.

 

I really want to hear a Sony ECR electret someday but the prices skyrocketed so I'll probably never own one. Guess I gotta make do with my 15 or so other 'stats.

Edited February 7, 2014 by mypasswordis

[nikongod]

Wow, all kinds of crazy designs back in the day... and bias at -300V potentially means finally a headphone that does not use a modified Stax driver (that isn't Koss/Beyer/Sennheiser/Sony)? Would be very interesting if that were the case.

 

It does not make a difference if the bias voltage is positive or negatve, just its absolute value - 300volts away from the average stator voltage.

 

If I am not mistaken, the trend is towards positive bias voltages because they tend to repel dust where negative voltages tend to attract dust. 

 

I will try to remember to snap some clicks of my Gamma Pros later. 

[mypasswordis]

I know it does not make a difference if it's positive or negative, but normal bias for Stax is 200-230VDC. It could be that they decided to run the Stax OEM drivers at 300, but it's more interesting to think that they had different drivers made.

 

What do you think of the Gamma Pros vs. any of the Lambdas?

[studioluc]

Hello to all, and you're welcome, spritzer, I found these very rare audiotec, and was curious to know if they would make some of you curious too.

when I sent the headphones, they had an important imbalance, that made one of the ways sound very poor compared to the other ( but really much lower)

( I am luc)

[spritzer]

Well it could just drive a Stax unit harder but I think they might have their own design.  The PWB designs had their own drivers even if they were heavily based on the Stax stuff. 

 

Edit:  Hi Luc!!    The imbalance is pretty much gone now with the left side being just a bit louder

Edited February 7, 2014 by spritzer

[studioluc]

all right.

you're a cans magician.

[Ali-Pacha]

They are electrets but Audiotec also made full blown electrostatics as I've seen the schematic for the energizer.  Bias is -300VDC...

291V. Nitpicking 

http://www.audiovintage.fr/leforum/download/file.php?id=29065

 

Ali

[spritzer]

Maybe measured but it is a 150V transient suppressor into a voltage doubler so circa 300V. 

[poussi_pousse]

Hello to all,

 

I would like to add some info about this headphone :

 

- it's a CES (Casque ElectroStatique) from Audiotec (France).

- the version presented is the electret version (from Audio-Technica, ATH-5 -> ATH-8 )

- the left-right identifier is the grey plastic on the cable

- there is no serial number because the driver aren't from Audiotec

- the old PCB is one of the two electrode from the original electrostatic headphone, if you see my photo you'll understand

- this headphone wasn't suppose to have an electret driver originally

- the six pins plug is silver plated so no bad oxidation.

- the 300V bias is for the electrostatic version only.

 

Here's the photo of the original (1972) version (full electrostatic) :

 

 

 

 

 

 

 

Poussi_Pousse

[mypasswordis]

Thanks for the in-depth info and pics! How does the full electrostatic version sound?

 

Here is a pic of my modded ET1000, I can't take anymore right now because I don't have them here.

[Tyll Hertsens]

 

Just wanted to note here that I'm willing to measure any of these old estats if interested.

 

Stax Mafia Makes Unrefusable Offer and I Begin an Electrostatic Headphone Measurement Program

Edited May 28, 2014 by Tyll Hertsens

[spritzer]

Hello to all,

 

I would like to add some info about this headphone :

 

- it's a CES (Casque ElectroStatique) from Audiotec (France).

- the version presented is the electret version (from Audio-Technica, ATH-5 -> ATH-8 )

- the left-right identifier is the grey plastic on the cable

- there is no serial number because the driver aren't from Audiotec

- the old PCB is one of the two electrode from the original electrostatic headphone, if you see my photo you'll understand

- this headphone wasn't suppose to have an electret driver originally

- the six pins plug is silver plated so no bad oxidation.

- the 300V bias is for the electrostatic version only.

 

Here's the photo of the original (1972) version (full electrostatic) :

 

Poussi_Pousse

 

Thanks for that info, much appreciated.  It's nice to know that the odd baffle plate was actually supposed to be a stator.  Always seemed that way to me but no way to confirm. 

 

Not sure why these drivers are in there but it looks like they came from the factory like this.  There are only four wires in the cable so either it had to changed or they were always like this. 

[studioluc]

Hi there

Coming back to this post, I discover what poussi-pousse said. Poussi-pousse, can you write to me ( in french, I suppose, as you are like me located in france) ? I have another ces headphone like this one, and I would like to be able to make the difference between electrect and electrostatic ces headphones.

thank you

luc

[Bingturong]

Sorry for reviving the thread but don't know anywhere else in the site I can post this, got something curious. A Napolex NSA-3