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The Headcase Stax thread


thrice

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6 hours ago, spritzer said:

Ouch...that is not good!!  The King Sound were some of the worst electrostatics I've ever tried.  They tick virtually every box in the "wtf were the thinking" list. 

I've tried KS-H4 on my SRM-1/mk2 pro, it was utterly disappointing...blown away by Lambda NB / Gamma Pro. Oh, and BTW Birgir, sorry for the match yesterday :P

Ali

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12 hours ago, n3rdling said:

Thanks for the EtherE impressions, that's pretty much how I heard them too.  They remind me much more of the KingSounds than Stax in terms of sound signature.

That can't be possible. The reseller in the focal utopia thread at the other site ( who sells Woo, Cavalli, Mr. Speakers and Focal, but not Stax) said that Stax 009 are vintage and antiquated, and that it is easily bested by the Ether E, and that the Ether E will be the premier estat once released. I hope folks aren't saying that either he is an idiot or a liar.

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In other news, I just got some used HE90 drivers for my frames.  I don't think the electrostatic museum is complete without an Orpheus...  :) 

They have some slight channel imbalance which I'll have to look into but I think they are mostly made out of glass as Senn always stated.  Gold plated diaphragm is likely BS but the black plate which holds the drivers is certainly glass and it has the same edge finish as the stators.  The spacers are clear though so might be some form of plastic. 

2 hours ago, Ali-Pacha said:

I've tried KS-H4 on my SRM-1/mk2 pro, it was utterly disappointing...blown away by Lambda NB / Gamma Pro. Oh, and BTW Birgir, sorry for the match yesterday :P

Ali

Thanks.  :)  The team did just receive a hero's welcome with the downtown area full of people. 

http://www.ruv.is/frett/sjadu-otrulegar-mottokur-a-arnarholi

That's a lot of people... 

2 hours ago, GeorgeP said:

That can't be possible. The reseller in the focal utopia thread at the other site ( who sells Woo, Cavalli, Mr. Speakers and Focal, but not Stax) said that Stax 009 are vintage and antiquated, and that it is easily bested by the Ether E, and that the Ether E will be the premier estat once released. I hope folks aren't saying that either he is an idiot or a liar.

Yup...he's probably right... :P 

1 hour ago, kevin gilmore said:

ether e not shown with ll2 or ll2t?

these would not be the first stats to require 2500vppss

 

My issue is the utter stupidity of not adhering to the standard set by Stax.  King Sound certainly made their own cables and sockets, it's just too bad they suck so bad. 

Stick with the 1200Vppss standard.  If Stax have been able to do so since 1982 how come they can't do it? 

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Ok...I had an interesting morning.  It isn't every day that one takes apart HE90 drivers.  :)  Sorry no picks as I was too freaked out while handling something so delicate and well...fucking unobtainium. 

These were from the original production run so they needed some cleaning and one driver was imbalanced.  Let's discuss how they were made...  First of, the actual stators are indeed glass with gold deposits on them.  The connections to them couldn't be soldered so they have adapter plates on them which hold the dust covers in place.  The diaphragm is held in place with aluminum spacers and they are actually not glued together so access is excellent.  Be warned though that there are small plastic spacers all over the fucking place so I'd advise against opening these up.  :)  The diaphragms are indeed not gold plated and they have a lot of tension on them. 

Now for the imbalance, the offending driver had the diaphragms completely fused into one of the stators.  It had been this way for a while as the hole pattern of the driver was imprinted onto the plastic film.  I slowly peeled them apart and recoated the diaphragm on both sides and now they work perfectly. 

There was a small hole where the drivers had arced through but it has very little impact on the performance.  Small amount of noise from time to time but nothing as bad as an old Lambda Signature. 

The other driver might need a new coating as well as it seems to have some charge migration issues so that will be easy to sort out. 

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3 hours ago, chinsettawong said:

Birgir, if you have a chance, could you please make the dimension measurement?  I really wonder if the glass can outperform the PCB.  I can make a set of drivers for you to try. :)

 

 

The email I sent you some time back should have pretty accurate dimensions. 

Birgir, how can you tell the diaphragm isn't gold plated? The sputtered coating should be so sparse as to be almost invisible in order to get really high resistance. Did they use graphite instead?

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The diaphragm looks exactly like that of Stax or even the HE60.  Slight haze to it but other than that there is nothing.  I'm sure the whole gold plated diaphragm was a type from german and they were always referring to the stators. 

If I open them up again then I can take some measurements.  I'm sure the glass is a factor but the drivers also bear all the marks of massive QC issues.  Spacers all over the place... 

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Well thing has arrived:

DYfGY9Hh.jpg

When it showed up it didn't work and the balance input still doesn't work.  This is cheap...and I mean cheap.  The chassis work is beyond crappy and when it arrived both volume controls were loose.  Circuit wise it is really just an Egmont with a 10M90 plate load and a tale current source for the input stage.  Some huge omissions though such as any way to balance or control the offset of the amp. 

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would one more gain stage, and some output stage stability have killed them?  Maybe $499

of course then it would be similar to a srxplus or half a megatron

birgir can post the inside pictures, even with the crap case its still built better than any cavalli or ec I know of.

and once you play with nagra gear including the stuff that is 30+ years old, nothing looks like nagra, nothing feels like nagra, nothing is built like nagra, even the rotary switches are different from everything else.

Edited by kevin gilmore
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On June 20, 2016 at 3:56 AM, spritzer said:

  Circuit wise it is really just an Egmont with a 10M90 plate load and a tale current source for the input stage.  Some huge omissions though such as any way to balance or control the offset of the amp. 

Ha, sounds like I guessed right on the topology being an Egmont, but 6C5 outputs - really?  They're more feeble than half a 6CG7/6FQ7.

Edited by JimL
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7 hours ago, JimL said:

Ha, sounds like I guessed right on the topology being an Egmont, but 6C5 outputs - really?  They're more feeble than half a 6CG7/6FQ7.

It pretty much had to be an Egmont unless it used some obscure dissimilar dual triode.  I might modify it and add a stage if there are any tubes that fit the octal socket and draw about 0.3A of filament current. 

7 hours ago, Arthrimus said:

So... how does it sound? 

Not that great.  I've only tried it on my test bench with 207's but coming off my usual diet there of Carbon's, KGSSHV's and KGST's...it's not that good.  Very weak bass and top end performance, sounds slightly "vague" which is probably due to the massive offset on the output. 

7 hours ago, Dusty Chalk said:

Fluctuations in line voltage?  (normalized)

They are proper VU meters with a drive circuit hidden underneath the main PCB.  I'll try to take some pics today to show how it works. 

5 hours ago, wink said:

Losa loud mains hum. perhaps? otherwise it depends on the headphone/earspeaker connected.

There is no hum at all but I'm not happy with the common heater (center tapped) for this thing.  It is running the cathodes at -380VDC so any heater/cathode barrier is long gone

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Well it did end up costing me about 730$ all in so not that cheap.  Fees in China, shipping from there to here and finally customs BS here.  I'd rather have a SRM-323S but you know... 

I also need to do a lot of work to it before it is safe to use.  It's impressive that almost none of the screws in this chassis actually work.  Everything is loose and rattling, screws are too short with no actual purchase and the builder has never heard of lock washers. 

Now some pics, as you can tell by the bottom of the board, this is bodge city!! 

PZg0XsLh.jpg

sjQkgAUh.jpg

The PSU is completely unregulated and pretty much as basic as they get.  CRC filters but that's it. 

xyVL1fCh.jpg

Finally the VU circuit.  Clearly off the shelf unit like the delay line above. 

MDNEuHrh.jpg

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