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The Headcase Stax thread


thrice

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6 hours ago, Whitigir said:

I grabbed my DAC to go with my Carbon and new found addiction about Stax ! such expensive and dangerous Addiction

 

 

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Nice brushed aluminium setup. Iam a huge Stax fan too. I have the 007 MK1 and waiting for a new amp. So currently without an amp.

 

Musical bliss the stax, if you do decide to upgrade get a higher end DAC and things will change dramatically.

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Now that all fear of taking apart Lambda drivers is gone I went out and acquired a Lambda Signature with channel imbalance. 58e7d7c114ba8_LambdaSigDriverRecoat.thumb.jpg.eed6a54fa6e69d5c816b68b50a3265d6.jpg

Drivers came apart just as easily (not incredibly easy) as my LNS driver. Recoated and singing beautifully. Lambda collection intensifies!

Edited by Arthrimus
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On 3/29/2017 at 8:09 AM, DefQon said:

Goof Off is good but IPA 100% usually works for me to clean off the remaining adhesive after scraping most of the sticky shit off.

The lab grade stuff becomes 95% or lower, as soon as you open it, unless you live in a 0 humidity environment, so there is really no point in buying it for most uses.  91% is cheap and cheerful and easily bought.  Isopro isn't nearly as toxic as Methanol, but I wouldn't recommend making a martini with it.

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LOL.  Methanol is NASTY stuff.  I used to use some for water/methanol injection in my race car before I went to turbos (far more efficient and cooler than supercharger).  Made the mistake of buying some to mix my own.  I should have just bought the pre-made stuff but I wanted to know what I was putting into the motor.  Control freak I guess...

HS

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6 hours ago, Tachikoma said:

So...  how do you guys get balanced drivers when recoating the drivers? I've tried to recoat my SR-5 drivers a few times now, and the balance has been an absolute pain in the ass to get right.

A lot of time recoating the drivers can solve the imbalance problem.  If it doesn't, there might be a leak of the bias voltage somewhere.  Please check also the cable and all of its solder joints.

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Greetings, headcases, this is my first post.

I've gone through this whole STAX thread with mounting alarm.  First I learned that Woo WEEs were badly designed and had the potential to destroy cans.  And then that it seems that it had actually happened several times!  There are not many engineering projects that are simpler than designing a transformer/biasing box for electrostatic headphones.  How could somebody get this so wrong?  This doesn't raise my esteem for the average designer of boutique HiFi gear.

So what's to be done?  My first idea was to insert 4.7Meg resistors in series with the bias output, but maybe this is not sufficient.  Later in the thread Birgir talked about putting his own biasing board.

Did somebody ever trace the schematics for the WEE?  Have there been variations during production?  Has anybody written up the procedure to make them safe?

I'm a speaker guy with a budget, and not a heavy heaphone user, and a KGSS or whatever is out of the question for now.  The WEE seemed an excellent choice for me, since I own two high quality speaker amps, and an SRM-323 (mine's a 323II FWIW) won't drive my Birgir-modified Sigmas properly.  I hit on the Sigmas five years ago after I Googled "headphones for people who don't like headphones" and really that's what they are and I love them.

I haven't opened the WEE yet but it's disconnected now...
 

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Thanks for the tip, but this posts seems to be specifically about the SRD-7...  does anyone have the circuit diagram?  I know what the bias supply looks like in recent Stax (active) energizers, but first and foremost I'd like to know how biasing is done in a WEE.   I know that according to Birgir it's a voltage tripler, without any protection whatsoever.   Once I know this (I hope someone traced the circuit before, else I'll do it myself) I have to decide wether to tamper with the existing setup, or change the biasing board, as Birgir did at least one.

I said my sigmas are Birgir-modified, and in this particular case he put SR-303 drivers in there, so they are pro-bias.  I know he has several Sigma-404s under the belt.

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58ebd1d5ddcce_Stax_HV_Supplycorrected.thumb.jpg.1fab0ed409be64b7ff718d6fef9d87b5.jpg

This is what you want. I've built it several times. Only issue is R103 and R104 should be 4.7m. You probably want to replace the bias circuit in the WEE entirely if you want to be safe.

Edited by Arthrimus
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Thanks a lot Arthrimus.  Now's my chance to figure out how a voltage doubler works.  Unless I'm completely out of it, your circuit is meant for 117V, right?

Pondering over this circuit reminded me that the WEE has a voltage conversion switch... and something clicked in my head.   What, do they have a transformer to handle AC in there?

And it looks like it...  talk about overdesign.   At least this gives some kind of protection, same kind as razors in bathrooms.

 

WeeInside.jpg

Maybe the cans are not well protected, but at least their users are.  That's something.

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It might be that they have to have an AC transformer if they want to be able to ship internationally.  In Germany the standards for power outlets/plugs allow you to swap the hot and the neutral, the ground being symmetrical.  Unlike France where you can't do this (but the EEC specs are such that the most standard type of plug in our part of the world works for both countries).

So there are German amplifiers whose user's manual tells you to try both sides and choose the one that sounds best.  And from my experience there is a difference sometimes.  Germany not being a third world country, they have to have quite stringent safety regulations for appliances, to take account of this symmetry.

Really gotta open that box.

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On 08/04/2017 at 5:12 PM, Tachikoma said:

So...  how do you guys get balanced drivers when recoating the drivers? I've tried to recoat my SR-5 drivers a few times now, and the balance has been an absolute pain in the ass to get right.

Re-coating it a few times helps. I've never run into any issue with imbalance problems after both drivers are coating, be it anti-static gel/spray, staticide or self mixed/dissolved elvamide or however you spell it.

 

The key is to ensure the diaphragm is coated evenly across the surface area and not one side more so then the others. 

Edited by DefQon
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