A S.E.X. for Stax. Putting the E back in sEx :)

[johnsonad]

Last night I put in a pair of 1uF ClarityCap MR caps thanks to Rob (Corndog71).  There is one word to describe these things and that is clarity.  What a difference in sound compared to the AudioCap and Auricaps!  Don't get me wrong, the Auricaps sound great and are cheap compared to other caps but these MR's are impressive in many ways.   Here are a few of our initial impressions.  On the initial attack of the notes, especially piano the Auricaps are rounded off where as the MR sound correct.  Strings finally sound like strings, especially with violin in the upper octaves.  The soundstage (headstage) has moved forward some and instrument placement is closer to that of my stereo.  Detail is amazing and better than my stereo at this point.  Listening to Brahms Ein Deutsches Requiem, Wiener Philharmonker (F32G 20249) was beautiful and we could understand the words which we couldn't do before. The fullness to the midrange is thinner and this could be the deal breaker on these caps.  The sound is overall detailed but not painful to listen to.

 I'm amazed at how much the PF cap can influence the overall sound.  I've got a few other mods to make and trial to include 18uF ClarityCap SA's in the power supply and trying various coupling capacitors. Maybe a coupling cap that is a little heavy in the midrange will help to balance it out some.

  Given the outcome of this trial it makes me wonder how much of a change I would get by putting in MR or Auricaps in my BeePre? 

[johnsonad]

Two changes.  First, I switched back to the Auricaps from the Claritycap MR's.  The MR's are more accurate but I like the tonal presentation of the Auricaps better at this point.  The Auricaps make the digital nasties a little more palpable.   

Second I shoe horned in the Claritycap SA 18uF's as replacements for the 22uF electrolytics.  There were no changes in voltage that I noticed though they just barely fit under the hood.  There where no earth shattering changes from the get go. I do notice a little more hum than before.  I'll let them settle in some and get used to the sound, then change back to the electrolytics and give impressions. 

 All in all, I've very happy with the sound.  The soundstage (headstage) has opened up with both width and depth. The detail is outstanding and the tonal presentation is inviting.  I can't remember enjoying listening to headphones this much in a long time.  Looking back on all the headphones I've owned in the past (HD650, HD600, Sony SA5000, Grado SR60, Headphiled Sony CD3000, Audio Technica AD2000, Denon D5000, Denon D2000, AKG K340) these are my favorite (sound wise, though not in comfort).  The S.E.X. compliments these earspeakers and gives a platform where the sound can be  tailored to an individuals preference.  For what started as an experiment, the end result is just what I was looking for.  If you're in the area and would like to give them a listen, let me know. 

[xcortes]

Questions (PJ?):

Would a Magnequest ex0 173 work instead of the Sowter? And, can something like this be done for the Mainline?

Thanks,

[johnsonad]

I had considered this as I've got a pair.  The short answer is no.  They are a 1:1 and not rated for it voltage wise.  PJ thought that Mike may have an odd ball in his catalog but it was stretching it.  O' netics said they could wind something up to order as another option.  Not sure on the Mainline and what it needs. Maybe PJ will chime in?  You could beta test it in your big headphone rig if you have iron that would work. 

[johnsonad]

Shoot Mikey the question. There was a reason though I can't remember it for the life of me.  These work out better in the end in my S.E.X. build having a 1:2 ratio, stepping up the voltage swing and allowing me to run the amp in a lower distortion range.

[xcortes]

I think the problem is exactly how much volts they can take. I read that they can take 100v rms max (but not from Mike). If so they would be delivering 50V on the secondary or 97dB "max"

[johnsonad]

PJ had wanted at least a 200v swing. I believe I posted mine reaching 240 something.  97dB is plenty loud for headphones in my experience.

[tdogzthmn]

I picked up an SR-507 +SRM-600LTD. combo today and letting it break in a bit.  Initial impressions are very favorable.  There is definitely something special to the sound of these headphones.  Although I would be interested in modding my SEX to work with my STAX I need it to drive my Orcas!  If a dedicated STAX amp circuit is ever dreamt up I would certainly be interested.  Many people seem to think the Headamp BHSE set the high bar for Electrostatic amps, which I think is a hybrid design. 

Anyway, having fun listening to these new headphones.

[tdogzthmn]

Found the background on my SRM-600.  Here's the specs listed for it online:

"HIGH-POWER DUAL TRIODE "ECC99"
All-new driver unit with "ECC99" high-power dual triode on board - designed for best dynamism and vividness of sound. An all-new driver unit has been launched to enjoy STAX ear speakers with the best sound. The excellent performance of the unit opens up a new dimension of music reproduction full of emotion. The output stage of the unit has adopted a high-power dual triode "ECC99" from Slovakia JJ Electronic that draws a lot of attention through its high-grade vacuum tube technology and manufacturing. The overwhelming dynamism and freshness of its dazzlingly vivid sound enhance further the attraction of ear speaker listening pleasure.
 
PURE CLASS A, BALANCED AMPLIFICATION
The newest hybrid type driver unit with FET input and dual triode output, adopting pure class-A balanced amplification circuit. Output stage employing "ECC99" high-power dual triode. The vacuum tube from JJ Electronic, one of the best and most-advanced devices available today, is manufactured with the assembly accuracy of

[Doc B.]

The overwhelming dynamism and freshness of its dazzlingly vivid sound enhance further the attraction of ear speaker listening pleasure.

Hey PB, where's that hyperbole circuit you drew up?

[tdogzthmn]

^ Marketing fluff is often funny and exaggerated, but my experience with listening to this amp has shown those descriptors to be pretty accurate!

[johnsonad]

Alright, back on topic and talking about my S.E.X. project

Tonight I installed a couple of switches and the OPT's that came with the kit and for some unknown reason it worked right away.  I'm now able to use my S.E.X. kit with both my speakers and the Stax headphones saving quite a bit of change and with the flip of two switches I can move between the two.

This is the first time hearing the S.E.X. with my speakers and it does sound good!  I'm using a 1.1uF PF cap and the OPT wired for 8 Ohms.  They seem to have lost lower mid bass and  bass though (less bass and more of an upper mid emphasis) and I'm wondering if I should very the PF cap size or try a different impedance on the OPT's?  Any suggestions from the head shed here? Maybe the transformers need to break in some??? I'll mic the two amps this weekend and post the curves. It may be that the lower mid bass and bass need a bump is all. As of now the highs are a little painful with my horns.

There is very little hum with my 100dB speakers and I must place my ears next to the drivers to hear anything.  The soundstage is deep and the room sounds realistic.  I'm using some Ruskies to start off with to included a 0.13uF SSG silver mica and a few paralleled K40's for the PF. 

[Paul Joppa]

Yes the transformers will need ~50 hours of music to break in. Like caps and speakers (though probably for different reasons) the bass needs time to wake up, and the treble needs time to get rid of the edginess. Just my experience, YMMV, etc.  :^)

[johnsonad]

Thanks Paul! I'm looking forward to this break in. There is some magic back there waiting to let loose!

[johnsonad]

24 hours of burn in and a change from the SSG silver mica caps over to another K40 (coupling cap)  and things are starting to take form. A little hazy still but getting closer with great potential!