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Koss ESP-9 electrostats, worth it?

Discussion in 'Headphones (full-size)' started by taowolf51, Mar 13, 2012.
  1. Taowolf51
    How are they? How would you compare them to modern headphones (like the ones in my sig)?
    I may have an opportunity to pick these up with their energizer for $200, and the allure of my first electrostats is tempting.

    So has anyone heard them?
  2. idletime1213
    They're great! They're bassier than your typical Stax, and maybe not as smooth but still retains an electrostat-like sound sig.

    $200 is a steal.
    Edit: whoops, thought they were the ESP 950. Haven't heard the ESP 9 yet, so disregard the above statement.
  3. nick n
    You may have to open them up and check the foam inside it may have deteriorated and made a mess inside. Also they are apparently heavy, may have to watch for corrosion on the copper inside, and may need replacement pads, and an internal cleaning all around.
    A couple of links:
     Be aware also that the energizer box if it is the earlier model must be used on an amp that has a common ground or you're asking for issues.( not very nice what it will do to the amp ). I think the later adapter box versions may have dealt with that aspect ( E9B?)
    Just some stuff to watch for. I hear they are supposed to be pretty nice sounding though after the needed work. I'm still considering one down the road as well.
  4. Taowolf51
    How can I tell if my amp has a common ground?
    I may be using them with an old optonica sm-4545 stereo receiver (mid-late 70s).
  5. nick n
    oh wow. Those Optonica's were Sharp's high end models. Hmm not sure about that particular model, maybe ask around the other forums section. Try here to start. A lot of people here are also active on AudioKarma and other hifi sites so this thread will be full of knowledgable folks. http://www.head-fi.org/t/537704/calling-all-vintage-integrated-receiver-owners
    they'll probably be able/eager to help you out.
    Which adapter box does the Koss come with? The regular E9 or a later different model #?
  6. Taowolf51
    The receiver is something else I'm trying to pick up at the moment, so it may not be what I use.

    Oh nice, haven't seen that thread before. Got tons of questions!

    It didn't say e9b, but the serial number had a -c at the end. No idea if that's important.
  7. dogwan
    Bumping an old thread.
    I have a pair on the way from Da'Bay.
    Any mod sites for the energizer and/or cans?
    Tried Google and Head-Fi and looks a little slim.
    Not afraid to tear into the energizer if it's worth it.
  8. spinlps
    Would be interested in what you find. I picked up a pair of ESP9's with the E9 energizer this weekend. No power cord for the E9 but they sound pretty good connected to my Harman Kardon 730's speaker taps. Will be ordering pads and searching for a power cord ASAP.
  9. dogwan

    I've been loving mine. Amazingly the pads are only about 1/2 flat, still have oil and holding.
    I did go into the cups and cleaned out all the old decaying foam.
    Replaced the old carbon comp resistors in the cans with 2% carbon films and the slight imbalance disappeared. Had to go to some pains to restore the circuit boards in the cups.
    I'm currently working out a headband mod to make them more comfortable. Also contemplating surgery on the pads to clean out the old oil and fill them with something like "Slime" for bicycle tires. Thoughts are the it will be denser than the oil and self sealing, and should still be flexible enough to provide a good seal on the head. A simple tube patch should be enough to re-seal them.
    Another mod I intend to do is to replant the innards of the energizer to a larger case to get the PT's away from the circuit boards and all the signal carrying parts. Additionally will install real speaker binding posts so I can use real speaker cables instead of the flimsy tinned copper leads that are pig-tailed out of the energizer.
    At some point I planned on starting a new thread to document the above mods when I've made some significant progress.
    P.s. Let me know if you need the owner's manual and schematic. I have them in PDF form.
  10. DivergeUnify
    I feel they blow away the HD650s... best headphones I've heard.  They own... hard 
  11. Thatch
    A good source for a gel would be the wrist pads you can buy for key boards. Easy to cut up but very tacky, a bit of flour or talcum takes care of that and it won't run or leak. I've used them for isolation purposes and all you need are scissors to cut them up. The insides are like sticky jello that won't melt.
    I am going to change the cord to a computer type input and build my own with big Beldon wire from home depot, add an EMI filter if there is room. I ought to be getting mine in a week, Ebay,$150 with shipping. No power cord. I need to send of for fresh foam.
    Has anybody tried low powered single ended tube amps?
    I like the idea of using good BPs and better wire. Maybe some better electrolytics, those have to be getting a bit dried up with age.
  12. Thatch
    Strike that. I didn't try melting the gel in anything but the microwave but evidently only a high heat will do. There is nothing in that gel that will melt from microwaves and the dish it was in got very hot without doing anything to the gel. The headphone pads will not come apart so you can't stuff them. I might put a propane torch on the stuff outside and see what happens,  but I can't imagine even a flavor syringe not getting clogged by this stuff, or it might never get back to permanent Jello after it breaks down.
    The tire gel is probably a great way as long as it doesn't harden all the way later.
  13. Thatch
    On another subject if anyone has a clear schematic to copy from a manual the one I received with mine is too blurry to make out well. I think I do need to tear into the box and recap etc and having things on paper that I can read would make me feel better. I didn't get a cord with mine and I think I need one to get it charged up so it won't make so much noise doing so from the speaker hook up cord, which seems flimsy as well.
  14. Mahay
    For everyone who experienced discomfort with the Koss ESP9 due to weight and clamping force of the headband, here I bring you an expensive solution. I'll take the credit for this design since I couldn't find any similar picture online even though the headband is from Stax SR Lambda. Anyway take a look at the picture and enjoy.
    Very very comfortable. I can't even feel the weight of the earcup and my ears feel so much relaxed. I have been listening for more than 3 hours and I don't feel anything that bothers me. I am listening to Muse - Supermassive Black Holes while writing this comment...
    Sound quality
    Oh boy! Always amazing, and the bass... man .... The can go deep and very detailed. Same for midrange and high. I think the headband of Stax Lambda Signature or the bigger frame work the best.
  15. nick n
    What aftermarket pads are you using?  Thanks for the post very great idea.

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