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deepak

Koss ESP/950 electrostat thread

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Looks interesting, how hard can it be? :)

Very hard since most of the amps sold on the market don't function correctly, eat tubes for breakfast or even damage the headphones. I know of at least two Blue Hawaii's that have gone up in flames and even if you can get it to work, it isn't running at 100% since the schematic isn't complete and lacks some very important bits. The Gilmore 0A2 amp would be much easier to build and just about anyone can build an Egmont (except Rudi that is).

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For a full system that can be run off batteries anywhere (I take mine with me when I am out of the country for a while) they are a bargain even at full price.

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Especially considering that full price ($650 on ebay) has an extra 25% knocked off ATM.

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<snip>

it isn't running at 100% since the schematic isn't complete and lacks some very important bits. <snip>.

What's missing in the schematic? I assume this is the BH you are talking about?

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What's missing in the schematic? I assume this is the BH you are talking about?

Yup, it's the BH that I'm talking about and if it was supposed to be known it would be on the official schematic.

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Especially considering that full price ($650 on ebay) has an extra 25% knocked off ATM.

Can someone point me to this? 25% off the $650 ish?

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Can someone point me to this? 25% off the $650 ish?

See second post in this thread. These were the instructions I used, and now I'm hooked :-[

It takes about a day for the cashback to show up in your live.com account. Assuming you followed the instructions there will be a picture that says "get XX % back through MS cashback" when you click buy it now. If it's not there don't buy the item, and retry the instructions.

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I successfully completed the recable with the Stax extension cable. Let's just say that out the KGSS, it's a totally different world than with the E/90. I won't do much listening tonight because I'm tired and will go to sleep soon, but I'll try to put some impressions tomorrow. Unfortunately, I think some dust infiltrated the right driver and I get an annoying squeal, I'll also have to investigate that tomorrow.

How do you get the cups open? I'm having trouble :)

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If I remember correctly, there's a layer of black foam under the earpads that is glued to the plastic. There are screws at the 4 corners, so you can just lift the corners to see the screws or remove the whole sheet of foam like I did. After that, it should be pretty straightforward. The pads are a bitch to put back though.

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Ok, and just because I'm a moron:

cable goes:

+ B - - B + on both stax and koss cables?

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Just as a reference for anybody else who might read this thread, with Stax cables the pinout is the following: Of the three wires which go to each ear, the wire with the line printed on it is +, the wire in the middle is the bias and the last one is -.

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I've always wondered, if i swap the + and -, technically it should make no difference right? Assuming the bias connection is left alone and of course this swap is carried out on both ear speakers.

The + and - membranes are identical no? :confused:

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That it is Kevin. It surprised me there wasn't a similar one for stax.

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I've always wondered, if i swap the + and -, technically it should make no difference right? Assuming the bias connection is left alone and of course this swap is carried out on both ear speakers.

The + and - membranes are identical no? :confused:

It depends whether you believe in "absolute phase" or not, and whether you can hear it or not. I personally believe in it, however I don't believe I can hear it with 99% of the music that I listen to.

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Modifications

As mentioned above ESP/950 can be used out of Stax amp or Stax compatible amps. There several ways to modify the headphones to acomplish this.

  1. Replace the cable with Stax cable
  2. Re-terminate the cable with Stax plug
  3. Re-terminate provided adapter cable with Stax plug

The benefits are different for each approach. Using a better quality Stax cable should improve the overall quality of sound, but will void the warranty. Re-terminating original Koss cable will eliminate additional connection that will be there if adapter is used but will also void the warranty. if you are not concerned with voiding the warranty you can do either 1 or 2, some users prefer to have excellent life time warranty thus choose to make an adapter cable.

FWIW, I sent my Koss ESP950 to the factory 2 weeks ago without any cable attached for a buzzing problem in one of the drivers. I'll report back when they get home. Worst case, if they don't want to replace it, I'll just solder back the original cable and send the phones again.

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I've always wondered, if i swap the + and -, technically it should make no difference right? Assuming the bias connection is left alone and of course this swap is carried out on both ear speakers.

The + and - membranes are identical no? :confused:

There are + and - stators and they are identical or we would be seeing a lot of distortion. Like Dusty said it is all about absolute phase and I can hear the difference easily. I even made a cheater plug that reverses the phase on Stax headphone so that I can compare... :rolleyes:

Is that thing still flagged for lack of references? :palm: I really have to make good on my promise and write a few articles for Dmitriy's site... :-[

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