[flipflop]

thanks too for listening. it seems there isn't a lot of interest in these 'phones, unlike the PRO4AAA and the electrostatic ones.
 
yeah, i really do think these drivers have potential. they are quite capable across all frequencies (even sub bass).  this came quite apparent when i was switching between earpads.  leather pads brought out quite a bit of bass, while fabric ones made them sparkle.  still can't quite get a good balance between the two but with the dampened (with dynamat only) cups, leather pads seem to work best. velour would work with an undampened set.
 
i hope someone can identify the drivers and if they were used in other models.  if not in Koss, maybe in Sansui ones? my manuals have both the Sansui and Koss brand names printed on them.

 

[takato14]

i hope someone can identify the drivers and if they were used in other models.

Thats a 55mm Koss PRO series driver, the same breed used in early production models of the 4AA and 4AAA. ̶S̶e̶e̶m̶s̶ ̶K̶o̶s̶s̶ ̶w̶a̶s̶ ̶t̶a̶l̶k̶i̶n̶g̶ ̶o̶u̶t̶ ̶t̶h̶e̶i̶r̶ ̶a̶s̶s̶ ̶w̶h̶e̶n̶ ̶t̶h̶e̶y̶ ̶s̶a̶i̶d̶ ̶t̶h̶e̶ ̶A̶u̶d̶i̶t̶o̶r̶ ̶l̶i̶n̶e̶ ̶t̶e̶c̶h̶n̶o̶l̶o̶g̶y̶ ̶w̶o̶u̶l̶d̶ ̶"̶t̶r̶i̶c̶k̶l̶e̶ ̶d̶o̶w̶n̶"̶ ̶t̶o̶ ̶t̶h̶e̶ ̶c̶o̶n̶s̶u̶m̶e̶r̶ ̶r̶a̶n̶g̶e̶;̶ ̶i̶t̶ ̶a̶c̶t̶u̶a̶l̶l̶y̶ ̶t̶r̶i̶c̶k̶l̶e̶d̶ ̶u̶p̶ ̶i̶n̶t̶o̶ ̶t̶h̶e̶ ̶A̶u̶d̶i̶t̶o̶r̶s̶! -- Man I should check my release dates more; I could've sworn the 4AA was older than these!!



Here's a pic of one of my 4AAA drivers -- this one is broken but you can see the massive resemblance of the backside pretty well.

These drivers are rather capable and a couple of the koss models still present in my stable use them -- even some models in koss' current lineup have the same housing and magnet design! Both of mine are in disrepair however. I'll work on them eventually....

 

[flipflop]

Thats a 55mm Koss PRO series driver, the same breed used in early production models of the 4AA and 4AAA. ̶S̶e̶e̶m̶s̶ ̶K̶o̶s̶s̶ ̶w̶a̶s̶ ̶t̶a̶l̶k̶i̶n̶g̶ ̶o̶u̶t̶ ̶t̶h̶e̶i̶r̶ ̶a̶s̶s̶ ̶w̶h̶e̶n̶ ̶t̶h̶e̶y̶ ̶s̶a̶i̶d̶ ̶t̶h̶e̶ ̶A̶u̶d̶i̶t̶o̶r̶ ̶l̶i̶n̶e̶ ̶t̶e̶c̶h̶n̶o̶l̶o̶g̶y̶ ̶w̶o̶u̶l̶d̶ ̶"̶t̶r̶i̶c̶k̶l̶e̶ ̶d̶o̶w̶n̶"̶ ̶t̶o̶ ̶t̶h̶e̶ ̶c̶o̶n̶s̶u̶m̶e̶r̶ ̶r̶a̶n̶g̶e̶;̶ ̶i̶t̶ ̶a̶c̶t̶u̶a̶l̶l̶y̶ ̶t̶r̶i̶c̶k̶l̶e̶d̶ ̶u̶p̶ ̶i̶n̶t̶o̶ ̶t̶h̶e̶ ̶A̶u̶d̶i̶t̶o̶r̶s̶! -- Man I should check my release dates more; I could've sworn the 4AA was older than these!!



Here's a pic of one of my 4AAA drivers -- this one is broken but you can see the massive resemblance of the backside pretty well.

These drivers are rather capable and a couple of the koss models still present in my stable use them -- even some models in koss' current lineup have the same housing and magnet design! Both of mine are in disrepair however. I'll work on them eventually....

Wow, didn't know that these came before the PRO series. They seem a bit older style-wise.

 

[takato14]

Wow, didn't know that these came before the PRO series. They seem a bit older style-wise.

Surprisingly enough, the Auditor line housings and earpads used on the ESP/10 and Dynamic/10 were indeed older and ended up being OEM'd/licensed for use by Realistic (a RadioShack division) for their Pro-II and Pro-IIA models in the '70s and '80s. These share the same drivers as the 4AAA and 4AAA Plus, respectively, and will sound largely the same with the official Koss branded model having pads that seal better for a better bass response. Also of note, the Pro-IIA has a different (worse) headband.

The damping adjustments and quality control might not be quite up to the snuff of the Auditor, but the Pro II should be otherwise functionally identical to it. I can't say for sure that the drivers are identical though. Would be worth inspecting and measuring the parts if someone could get a pair into my hands!

At the very least, the driver housing appears to be the same and the damping disc seems to be the same as well -- high quality injection moulded nylon and crumbly urethane foam respectively. However, dynamics are very sensitive things that can be made to sound very different even with nanometer-scale adjustments to things like the voice coil depth, diaphragm thickness, magnet gap... the list goes on. I have been keeping my eyes out for a Dynamic/10 I could measure and test but the only one that likes to show up seems to be the ESP/10 -- which I do have, but without the (proprietary) energizer. Oof.



A very pretty housing, these ones have. They are technically open (while the Dynamic/10 is closed) but other than that back metal plate and the drivers they share the same parts. More comfortable than you'd expect and built beautifully!!

 

[Promick]

Koss TECH/2 is later version of Auditor. http://20cheaddatebase.web.fc2.com/koss/TEAC2.html