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The Headcase Stax thread

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The EL34 can handle 800V all day long and with equal power plus it is a far more modern tube design.  That's what I find so funny about tubes in general, people overlook that the tube design and build quality got better by leaps and bounds from the 30's to the 50's.  Onto the 60's, the sub-miniature tubes are nothing short of stunning works of engineering marvel.  Sure, cost cutting started to creep in but there is just so much nostalgia BS associated with this stuff.  "NOS" tubes (i.e. old rejected crap nobody would have used) is always better and we must use the oldest designs possible.  Where is the clamor for old transistors?  Go, go germanium!!!  ;) 

We should setup a non-profit organization with the sole goal of buying audio equipment and take it apart for the world to see.  I think Senn would be thrilled if we were to rip the HE1's apart...  :D 

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his week I acquired a sennheiser HE60 but it has some issues concerning the left channel. Let me explain:
First time I put it on I encountered the stax fart, it was very noticable. Whenever I flick the left ear cup, the buzzing/tizzing noises alters frequency, amplitude or volume etc. Its not a constant sound. And whenever I move my jaws the noises change aswell. Whenever I push the earcup ever so slightly towards my head it farts. Even if I flick the left earcup with my fingers gently the driver makes a 'pop'. the right driver only does this at a much higher force. I have had a HE60 in the past and I did not have any issues like these.

Does anyone have answers regarding this and on how to solve this, is it dust, is it an electrical connection inside the earcup that is loose? Or is the driver simply busted? 

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10 hours ago, spritzer said:

That's what I find so funny about tubes in general, people overlook that the tube design and build quality got better by leaps and bounds from the 30's to the 50's.  Onto the 60's, the sub-miniature tubes are nothing short of stunning works of engineering marvel.  Sure, cost cutting started to creep in but there is just so much nostalgia BS associated with this stuff.  "NOS" tubes (i.e. old rejected crap nobody would have used) is always better and we must use the oldest designs possible.   

I'd say that's an oversimplification.  For example, some of the triodes from the 1930s such as the 56 and 76 tubes are among the most linear tubes ever designed, as documented by Eric Barbour in issues of Vacuum Tube Valley.  6SL7 and 6SN7 tubes designed in the 30s are more measurably  more clinear than theircounterpart 12AU7,6CG7 and 12AX7 tubes from the 1950s, which were primarily designed to cost less.  OTOH he latter tend to have less microphonics due to smaller plate dimensions, so pluses and minuses, but not all on the later design's side.  And NOS JAN (Joint Army Navy) tubes that were sold as surplus in the 1990s and 2000s when DOD finally decided that they were never going to use those old tubes are nobody's idea of "rejected crap," as they were stocked after meeting military specs.

 

A lot of the advances in tube technology in the 1940s were due to the war effort and had more to do with VHF and UHF design for radar, not improvements in audio tube design.  As for materials, probably some improvements there.  

 

Lynn Olson has noted that early direct heated triodes are measurably very linear devices, more so than even triode strapped pentodes from later.  They do have disadvantages of course in terms of amplification factor, hum problems with AC heater supplies, etc. The 300B is one of the most linear tubes ever designed.  Not ideal as a stat headphone amp output tube because of its voltage limitations and its relatively high current requirement for best linearity, which isn't needed for stat headphones.

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Sure cost cutting was a factor with some designs but tubes had to become more reliable into the 50's so the build quality jumped by leaps and bounds.  Take the sub-mini stuff.  It was designed to be used continuously for years where it couldn't be serviced at all so yeah, these are far better tubes than the anything before them. 

Are some of them a bit more linear, sure but the designs were far more compromised in other ways. 

 

18 hours ago, gepardcv said:

Have you dissected an HEV90?

We have the full schematics of it but I did take my old one apart.  Classic Sennheiser, nothing but the cheapest shit possible is allowed to be used.  Then we have the small issue of at least half of them don't work due to the wrong implementation of the circuit.  4K7 output tube load in an electrostatic amp?  This thing can barely swing any voltage at all. 

15 hours ago, aRRR said:

his week I acquired a sennheiser HE60 but it has some issues concerning the left channel. Let me explain:
First time I put it on I encountered the stax fart, it was very noticable. Whenever I flick the left ear cup, the buzzing/tizzing noises alters frequency, amplitude or volume etc. Its not a constant sound. And whenever I move my jaws the noises change aswell. Whenever I push the earcup ever so slightly towards my head it farts. Even if I flick the left earcup with my fingers gently the driver makes a 'pop'. the right driver only does this at a much higher force. I have had a HE60 in the past and I did not have any issues like these.

Does anyone have answers regarding this and on how to solve this, is it dust, is it an electrical connection inside the earcup that is loose? Or is the driver simply busted? 

It's a HE60 so you will have dust inside the drivers, no way around that.  That is a likely culprit but they might also have arc'ed at some point forming a hole in the diaphragm.  This is possible when using them with so many amps so the driver could be pretty much toast. 

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4 hours ago, spritzer said:

Classic Sennheiser, nothing but the cheapest shit possible is allowed to be used. 

I was trying to shore up my aristocrat credentials the other day, and digging through some Greek mythology.  I noticed that Orpheus, the source of the world's greatest music, was married to Eurydice.  Eurydice was stalked, chased, and effectively killed by a minor son of Apollo: Aristaeus.

Pretty bold name for an amp, Justin :)

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9 hours ago, spritzer said:

Sure cost cutting was a factor with some designs but tubes had to become more reliable into the 50's so the build quality jumped by leaps and bounds.  Take the sub-mini stuff.  It was designed to be used continuously for years where it couldn't be serviced at all so yeah, these are far better tubes than the anything before them. 

Are some of them a bit more linear, sure but the designs were far more compromised in other ways. 

 

We have the full schematics of it but I did take my old one apart.  Classic Sennheiser, nothing but the cheapest shit possible is allowed to be used.  Then we have the small issue of at least half of them don't work due to the wrong implementation of the circuit.  4K7 output tube load in an electrostatic amp?  This thing can barely swing any voltage at all. 

Well, I have a somewhat different perspective on this.  I don't know that "tubes had to become more reliable into the '50s" as prior to that there was no other option.  In fact, if improved reliability was a major engineering goal you would think that the tube manufacturers would be putting out advertisements touting it.  They didn't.  They did promote cheaper 9 pin miniature tubes, e.g. 12A_7 vs. more expensive pre-war octals  such as 6SL7 and 6SN7, squeezing more elements into the same tube envelope with compactrons (less tubes, less expense), or putting in controlled filament warm up elements to allow manufacturers to run series filament heaters (less expensive) - do you see a pattern here?  The fact is by the 1930s, consumer tubes would last 5-10 years, which was "good enough."

 

In fact, the major factor for tube reliability is conservative operating conditions, which was understood in the 1930s - the longest running tube was a "Mazda AC/P pentode valve (serial No. 4418) in operation at the BBC's main Northern Ireland transmitter at Lisnagarvey. The valve was in service from 1935 until 1961 and had a recorded life of 232,592 hours."  A 1930s tube.  In the 1950s, they did introduce premium versions of the 6SL7 (5691) and 6SN7 (5692) tubes which were supposed to have a longer service life.  The way they did that is very simple, they just derated the tube so it was supposed to run at lower voltages, currents and power dissipation than its parent tubes.  Now, it is true that they made advances in reliability for specialized tubes which were used for trans-Atlantic submarine telephone cable repeaters, but AFAIK that technology never made it to consumer grade tubes - too expensive.

 

Switching to the other item in your post, would it be possible to show the schematic of the HEV90?  The working version, that is.

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The official Sennheiser schematic is out there but it is incorrect.  We never drew up a corrected one. 

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24 minutes ago, arnaud said:

An attempt at translating the latest Stax tour / interview: http://www.head-fi.org/t/829843/stax-sr-009-and-t2-successors-confirmed-for-spring-2017/45#post_13130037

cheers,

arnaud

Sir, I cannot thank you enough for this. It was a extremely good and informative reading.

As I understand, new flagship amp is coming and instead of making a new omega, they'll release 009 mk2. Am I right?

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Thank you Arnaud, for the elegant translation, which is largely accurate, including the innuendo and hesitation common to the Japanese idiom.  In reading the original Japanese, the only thing that STAX says with certainty is that a new amp is forthcoming, hopefully on sale by next summer.  They are "developing" a DAC function in the driver, but again, nothing certain.  The 2018 anniversary is simply a provocation, with no commitment beyond the wish to do something commemorative--

Comments on the 4070 were particularly frank, seems they'd abandoned them even before finishing production.

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Nothing in that article suggests that a possible T2 successor will be released in the future.

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A surprisingly small one.  There is a mild suppression in the upper midrange where you loose some "air" and the bass is clearly tuned like other Pro model Stax so lean but insightful.  Their major drawbacks are just how heavy and bulky they are.  Also the first ones are so uncomfortable that it isn't even funny. 

Ohhh and as I found out...stay far away from ones that have been serviced.  Stax will turn them into an unlistenable mess which sucks so bad that it isn't funny.  Now we all know that the SR-507's are garbage but those drivers in the 4070...holy fuck that was bad. 

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https://www.audiogon.com/listings/amplifiers-stax-srm-252s-portable-amplifier-for-stax-009-2016-12-29-headphones-07853-long-valley-nj

Quote

Here are a couple of Stax SRM -252s amplifiers, each has been modified to drive the STAX 009 Reference Headphones.  The mod alone cost $700 each.  These are serious units that allow someone to travel with the Stax 009.

Hahaha, WHAT?  Lots of wtf on quite a few levels.

Edited by Mr.Sneis

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WTF indeed.  Notice that those are 230V models as well so not the Airbow stuff from Japan. 

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17 hours ago, Mr.Sneis said:

Wonderful!  A mod that costs twice as much as the list price of the amp and can't get rid of the current drive limitations due to limited heat sinks. :palm:

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896cae33ecd02bc7f50896ef0e12932ee7a9d700a285d3de8fe7315f33a87d62_1.jpg

 

Well if one ask for extra 700 Dollars for a mod , I really want know what changed. I know it is EXTREMELY stupid but I want to know what they changed with that "mod"

Edited by Sechtdamon

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Just sold my SR-007A(sz2) and looking for a new pair of 007.

Is the 007mk1 still the best headphone stax have ever made,or the new 007 mk 2.9?

 

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