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The Koss ESP950 thread (ESP owners, please contribute! :) - Page 4

post #46 of 346
Thread Starter 
Quote:
Originally Posted by spritzer View Post
Damn it... now I have to buy two f these...

two of what? 007? 950?
post #47 of 346
Thread Starter 
Quote:
Originally Posted by edstrelow View Post
the last time I took them apart there were 4 slotted ports in the pannel holding the transducer. These phones are essentially open to the outside. So unless Koss has changed the design, a better seal at the ears won't actually give you the type of air-tight seal that you get with the Stax lambdas.

Of course you could try blocking the ports and using a better sealing earpad. I would expect some sonic differences then.
where are these ports? I went back to the pictures and couldn't find any, the baffle appears to be sealed......





--- update (10/18): I finally peeled the thin black foam layer all the way back, now I see the slots, 5 of them, they were kind of hidden by the driver mounting bracket so I didn't see them when looking at the backside picture..... these slots are all basically sealed by the double sided tape that attaches the foam layer to the baffle face, so I guess they are not gonna create much acoustic short between the back chamber and the front....

.
post #48 of 346
Quote:
Originally Posted by AudioCats View Post
two of what? 007? 950?
950... unless I can mod the baffle without destroying them.
post #49 of 346
Quote:
Originally Posted by AudioCats View Post
where are these ports? I went back to the pictures and couldn't find any, the baffle appears to be sealed......
the cloth on the baffle is porous. Hold it up to the light and you can see through it as well. It's almost like a fine felt.
post #50 of 346
Thread Starter 
but there is already an oval foam ring that seals around the front of the driver, maybe we need another foam ring in front of the dust cover film (seal between the film and the fine screen)?
Looks like I need to find some foam gasket material...
post #51 of 346
Quote:
Originally Posted by AudioCats View Post
where are these ports? I went back to the pictures and couldn't find any, the baffle appears to be sealed......
They are under the felt/foam that covers the drivers. You need to peel the felt/foam back to see the ports. As I said, unless Koss changed the design. I know that they have played around with backing, sometimes having it sometimes not.
post #52 of 346
Thread Starter 
Quote:
Originally Posted by spritzer View Post
Btw. You know you want some HE90 pads for them...
no way, at least not before I finish my silicon/silver cable....

Birgir, can you measure the bias voltage in your E10 energizer? come on, you are about the only person around here that has a E10....
post #53 of 346
Quote:
Originally Posted by luvdunhill View Post

The stock power supply is 6V 1A, and the battery pack option uses 6 C cell batteries.
My E90 stock power supply is 9V but it is unregulated and it goes as high as over 13V when I measured. I have given well regulated 12V power supply to E90 and it improved the sound nicely but not night and day difference.
post #54 of 346
Quote:
Originally Posted by AudioCats View Post
Birgir, can you measure the bias voltage in your E10 energizer? come on, you are about the only person around here that has a E10....
I'll dig out my VTVM tomorrow and see what I'll find. I'll also hook them up to a Stax amp.
post #55 of 346
I dug out the VTVM and it must be broken as I go no readings at all and I wasn't looking forward to opening up the E/10 so I just converted the ESP10 over to Stax. They run comfortable off the Pro bias but need more plate voltage then the normal Stax or Senn electrostat. My SRM-XH is nearly maxed out driving them at slightly loader then normal volume levels.
post #56 of 346
Thread Starter 
Quote:
They run comfortable off the Pro bias but need more plate voltage then the normal Stax or Senn electrostat. My SRM-XH is nearly maxed out driving them at slightly loader then normal volume levels.
so the Esp10 bias might be even higher than 570V?
post #57 of 346
Quote:
Originally Posted by AudioCats View Post
so the Esp10 bias might be even higher than 570V?
I don't think so. The D/S spacing is bigger then what Stax used as standard but the bias could be lower. Some designers prefer to have a lower bias with higher drive due to safety reasons and more excusrsion of the drivers.
post #58 of 346
I was finally able to snag a Koss E9 transformer for the ESP 9 to replace my old one which had lost its high frequencies due to some ill-advised modifications.( the story is too long to go into) Hooked up to a 100 W/channel Sherwood amp the ESP 9's now sound very good. Pretty nicely balanced, not quite the same bottom bass as the Stax 404/717 combination, and what seems like an upper mid-frequency dip.

Probably the main aspect of sound which is missing is the ambience and air of the 404/717. However the ESP 9 has a certain euphonic solidity of sound compared to the Stax. Possibly this is what some persons object to about some Stax stats, a sort of intangible airiness to the sound. I ma curious if this is due to using the tranformer instead of a headphone amp. I am still unable to get my other ESP to work properly on a Stax amp to compare.

This E9 has a switch on the back which appears to switch out the high frequencies, rather like what my modded E9 sounded like. I have not seen this before on an E9.

Also it has a 2-prong socket for a power cord, and so far I have been unable to find anything like it so I may have to either solder wires in place or use clips.

I have been running this unit satisfactorily in the self-energized mode.
post #59 of 346
Quote:
Originally Posted by spritzer View Post
I dug out the VTVM and it must be broken as I go no readings at all and I wasn't looking forward to opening up the E/10 so I just converted the ESP10 over to Stax. They run comfortable off the Pro bias but need more plate voltage then the normal Stax or Senn electrostat. My SRM-XH is nearly maxed out driving them at slightly loader then normal volume levels.
I know that the Koss ESP950 runs well off Stax amps. How does it compare to the ESP10? Given the variety of phones you have, you really should be writing up some comparative reviews of what they sound like.
post #60 of 346
Quote:
Originally Posted by edstrelow View Post
I know that the Koss ESP950 runs well off Stax amps. How does it compare to the ESP10? Given the variety of phones you have, you really should be writing up some comparative reviews of what they sound like.
I don't yet have the ESP950 but I'll buy it soon. The ESP10 is transformed by a good Stax amp but due to the extreme damping used they sound a lot like the ESP9 and 6. The drivers follow the same basic design and use the belt damping in the slots on the back of the drivers plus a thin layer of paper and then foam.
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