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Just bought Stax SR-009 (arrggg) but no amp

Jon L

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X2!  Now that is something I would take out a second mortgage to buy.   Electron LUV amps are like Frank Cooter for speaker systems.




Well looks and build wise, I am not qualified to comment on design and tube implementation.

EletronLuv are inspired by Sakuma's circuits. IMO Frank's designs are more modern and probably neutral.

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  • 2 months later...

I noticed this thread on HF where "Eric65" is using the Woo WEE with the transformer bypassed into Audiovalve and claiming great results on Stax SR009.  Any thoughts?  If true, one of the Stax transformer boxes could be modified the same way with Audiovalve, or use one of Spritzer's Stax bias units in a simple adapter box..


"I can add than the use the same Stax SR-009 headphone used directly on the Audiovalve RKV MK2 amp (NB : Woo-Wee box is used only as an simple bias voltage generator (580 Volt DC), and the two transformers (multiplier of voltage 1:50) of the Woo-Wee are bypassed) will even more far away : gain of transparency, more natural sound and more presence (especially if Siemens tubes are used for the amp RKV) and, in my opinion, more natural than the Electra amp, and with might better synergy that the BHSE amp for use with SR-009 (NB : I do not speak here of SR-007 mk1 headphone where the BHSE amp seems untouchable)."



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Well the Audiovalve spec is only 3 Watts max so nothing like the power of a BHSE or DIY T2, but then I suppose the 009 is easier to drive.


So if the transformers in the Wee are bypassed how is the bias voltage being supplied?


tech. describtion:

  • OTL - transformer outless tube amplifier
  • double mono construction
  • Alps volume control
  • 1 pair 6,3 mm stereo jacket for headphones
  • tubes: 4 * PCL 805 (PCL 85 or 18 GV 8 - german old TV "vertikal" ampl. tube )
  • power output: each channel 3 watt SINUS,  ( between 100 to 400 ohm loads )  
  • bandwide: 15 - 100 000 hz
  • damping 3600 !
  • distortion 0,002 % at 1 Watt-200 Ohm load
  • max. output voltage 80V
  • sens. 0dBm
  • IC - full autom. - controlled bias
  • class - a
  • power consumption min. 60 watt
  • size 360*200*120 mm (d.w.h.)
  • weight 6kg
  • patent full automatic servo tube biasing
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Kevin and I have been laughing about this post by eric65 today.  The guy is the king of fucktards, clueless to boot and I hope it's clear that this shit doesn't actually work.  If the amp had enough voltage swing for Stax, can you imagine how loud it would be with normal dynamics?  That's assuming they would even survive the abuse for more than a few seconds. 


My favorite part is about the 'stat impedance being a constant.  He can't read just one article about how electrostatics function? 

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Congrat!  I am totally jealous.  


Also, I would be interested in hearing people's opinion on KGSS vs BHSE for the SR-009 (for my future SR-009). 


Shelly, sorry I think missed this before, but with the thread resurrected I wanted to update my thoughts in amps for SR-009. Previously I posted a little about my KGBH with 009, and wanted to elaborate with some specifics about bass, mids, treble, and soundstage differences in my amps..


I've got both a hot-rodded DIY 400V KGSS and a KGBH with Custom CCS and Mullard XF2 (both built by Marc) which some people think would fall between a KGBH and BHSE.


With the SR-009 I experience noticeably better bass performance with the KGBH, as in more impact, slam, and depth. The KGBH also has a smoother and more refined treble response, while the KGSS is slighty more aggressive in the lower treble and slightly more forward in the mids which would suit my 007 Mk1 better.  Lastly, the soundstage of the SR-009 is even more enormous and deep with the KGBH vs the KGSS.  If I had to part with one, it would be the KGSS, but it makes a great spare amp for the bedroom and kills the HEV-70 with any stat.  


I've heard the BHSE and 009 at a few RMAF CanJams, and with Justin's newer Oppo source it was very good with 009 (not so good with the brighter Sony source he used before).  I've not heard the KGSSHV with 009, but with what I have here at home I think my KGBH is a better match for the 009 than the KGSS.  


If I had never heard the KGBH with the 009 I would have few complaints, but the tonal balance of my DIY KGSS is more suited for the 007 Mk1.  The Woo WEE is inadequate with the SR-009.  It's much better suited for the 007, but is too bright and forward sounding with the 009 and HE-60. I drove the WEE with an EMOTIVA BDP-1 75 watt amp, but haven't used it in about a year.

Edited by HeadphoneAddict
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Its French ingenuity and Gallic flair you know  :laugh:


I'd rather say, crazy people do stupid shit...  :)  I can understand the need to change something in the WEE though as it is just garbage.  Transformers not even remotely intended for this use and a bias supply which will kill the diaphragms.  Pure win there... 

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PS: the above mini-review was my acknowledgement to Jon L that one amp might suit one headphone better than another. But it doesn't take away from the fact that my KGBH is perfect with 009 and still quite good with 007, without needing a tube change. The 007 seem to tolerate a more forward or brighter amp like my KGSS better than the 009 can, but the more laid back and refined signature of my KGBH still suits them quite well.

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Can you get those amps to make some sound?  Sure but it will sound like shit for obvious reasons. 


A further point that eric is not well in the head, he's running the 009 single ended... :palm:  Even if the - stator is grounded then the THD is still orders of magnitude higher than when driven push-pull. 

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  • 1 month later...

Can anyone comment on the positive qualities of DHT's over other types of tubes? I know THD isn't the best place to start but I have noticed that they have relatively high figures, and whoever is reviewing the amplifier glosses over that and waxes poetic about "magical qualities". 


Also, I keep seeing mention of "the beast" from morgan jones' book, but the schematic has been lost over time. Can someone repost it?

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The last paragraph of that Stereophile test report says it all.  In the circuits DHT's are mostly used (i.e. as old as the hills) they are simply painting a pretty picture that's not truly accurate.  Similar in many ways to vinyl which has its issues and can't ever match the resolution of redbook but sounds "nice".  The whole notion that tubes have a "sound" bothers me no end, just look at the BHSE distortion data Justin posted on HF.  


Here is the Beast.  The quality is pretty crap as it's a huge schematic taken off a single page in a small book. 







Bonus points to anybody who sees why this one works but the WES fails so miserably?  Kevin also has a design with a dozen DHT's but he hasn't even let me see it.  Says I have to promise to build it before he does so....  :)

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845's aren't a problem, the EML tubes Kevin used in the front end of that other amp are....  Around 4-5k$ in tubes alone. 


The Beast is a pretty neat design.  The quality of the choke is crucial but it's nice to have CCS loaded front stages. 

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Most of our designs are finalized.  There are some offshoots which are discarded but the general idea is finished and then either improved with a later version or put aside.  Most have PCB's that go with them, either rough drafts or finished boards which is great when we revisit the designs. 

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