[justin w.]

Here is the video that shows how to do the DC voltage adjustments to the BHSE: http://www.youtube.com/watch?v=-obcsljIBxI
 
i made this video when I happened to have someone here to help hold the camera, unscripted, so hopefully it's clear enough.  i noticed that the view of the Stax headphone jack is not very clear at times, if someone has the video-editing ability to insert the Stax jack pin-out image into the video at the appropriate times that would probably be very helpful -- please let me know

 

[Golfnutz]

Quote:

Here is the video that shows how to do the DC voltage adjustments to the BHSE: http://www.youtube.com/watch?v=-obcsljIBxI
 
i made this video when I happened to have someone here to help hold the camera, unscripted, so hopefully it's clear enough.  i noticed that the view of the Stax headphone jack is not very clear at times, if someone has the video-editing ability to insert the Stax jack pin-out image into the video at the appropriate times that would probably be very helpful -- please let me know

Nice video. Thank you.

 

[spritzer]

Quote:

Dear Spritzer,
Besides having HV mosfets as outputs, could you tell us the differences between those to amps?
Regards
Erico

 
None of these amps (or any Stax made amps for that matter) have used mosfets for the output, they all use bipolars (BJT's).  The only wide scale production amp to use mosfets for the outputs was the HEV70 and we all know how good that was... 

  The KGSS and KGSSHV are more a like then different but three major differences, higher rail voltages (almost 50% in the IXYS version), constant current source for the third stage instead of resistors (Kevin had talked about this in the original KGSS article on Headwize but never finalized it) and the last bit, a vastly superior power supply borrowed from the T2DIY project. 
 
In terms of sound they are both wires with gain but slightly different.  The KGSS is warmer and a bit loose at extreme volume levels while the HV is brutally honest but never looses grip.  If there is something wrong with what you hear on that amp then look at something else in the signal path as the amp is not at fault.  It's not sterile in any way, just gets out of the way as any good amp should do.  The perfect amp should just do that, apply gain and be able to drive the load presented with no extra coloration's. 

 

[jcx]

there is the Koss E/90 - uses complementary Supertex Mosfets 3x series cascaded/totem pole and 2x paralleled to get the power and V rating with 550 V T0-92 parts - 48 24 total Q in all
 
http://gilmore.chem.northwestern.edu/koss.gif
 
http://www.head-fi.org/t/262845/the-koss-esp950-thread-esp-owners-please-contribute/285

 

[El_Doug]

guess it's all relative to the listener - when we had both an 007 and 009 connected to my BHSE, I couldn't stand the 009's blast when the 007 was at a comfortable volume.  though to be fair, I listen very quietly, so perhaps the difference between the two was more apparent
 
Quote:

We were driving a SR007A and SR009 simultaneously through my BHSE, and both sounded fine, though the SR009 was a bit louder.  We had the BHSE volume pot maxxed out, since we were using a preamp to manage volume.  The differences in volumes between the two were not drastic, and I was going between both headphones without any desire to change the volume.

 

[sridhar3]

Quote:

guess it's all relative to the listener - when we had both an 007 and 009 connected to my BHSE, I couldn't stand the 009's blast when the 007 was at a comfortable volume.  though to be fair, I listen very quietly, so perhaps the difference between the two was more apparent

 
Same here.  If the 007 was at my proper listening level, the 009 at the same knob position was wayyyy too loud.

 

[Asr]

Quote:

Here is the video that shows how to do the DC voltage adjustments to the BHSE: http://www.youtube.com/watch?v=-obcsljIBxI
 
i made this video when I happened to have someone here to help hold the camera, unscripted, so hopefully it's clear enough.  i noticed that the view of the Stax headphone jack is not very clear at times, if someone has the video-editing ability to insert the Stax jack pin-out image into the video at the appropriate times that would probably be very helpful -- please let me know

 
Just wanted to point out, for those following Justin's video, that the volume pot should be set to zero whenever headphones aren't plugged into the amp.
 
Moreover, for those new to electrostatic amps/headphones, the volume should always be set to zero before unplugging headphones, or plugging them in. Though this might seem like common sense, I've noticed at meets that not everyone practices proper amp-operation handling. In fact, I've seen that the majority of Head-Fiers (who you'd think would know better) typically unplug headphones from dynamic amps without bothering to turn the volume down to zero. It's not just electrostatic amps either - dynamic amps can have issues with this too, most notably amps like the B22. To that point, I previously owned a B22 that was "blown up" at a meet due to this very issue where an unknown Head-Fier unplugged headphones from it, without turning the volume down.
 
So the lesson here is: new-to-stats Head-Fiers should be extremely careful operating the BHSE and adjusting the bias on it. Ask questions here before doing anything you're not sure about.
 
This might be extreme advice but I'd strongly advise that no one should ever be unplugging electrostatic headphones from its respective amp at a meet, unless you're the owner and/or you know what you're doing. Because you don't want to be held responsible for damaging someone else's amp, right?
 
This has been a PSA to the new & imminent group of BHSE owners.

 

[sridhar3]

So, in other words, turn the volume up all the way before plugging in/unplugging electrostatic headphones.  Gotcha.
 

 

[deadlylover]

 
Moreover, for those new to electrostatic amps/headphones, the volume should always be set to zero before unplugging headphones, or plugging them in.

 
Could you please give a technical explanation as to why?
 
I've been plugging and unplugging my stats while on/music playing for years. 

 

[cobra_verde]

Thanks for posting the video Justin. Looks pretty easy.

 

[n3rdling]

I didn't think the volume thing was an issue with electrostatic amps, especially given the plug design.  I know it is an issue with some dynamic amps (infamously the B22) since those use an inferior plug/jack design. 

 

[daveDerek]

Quote:

Moreover, for those new to electrostatic amps/headphones, the volume should always be set to zero before unplugging headphones, or plugging them in. Though this might seem like common sense, I've noticed at meets that not everyone practices proper amp-operation handling. In fact, I've seen that the majority of Head-Fiers (who you'd think would know better) typically unplug headphones from dynamic amps without bothering to turn the volume down to zero. It's not just electrostatic amps either - dynamic amps can have issues with this too, most notably amps like the B22. To that point, I previously owned a B22 that was "blown up" at a meet due to this very issue where an unknown Head-Fier unplugged headphones from it, without turning the volume down.

Quote:

Could you please give a technical explanation as to why?
I've been plugging and unplugging my stats while on/music playing for years. 

 
yes, it would be helpful if you could explain just what the issue is with both e-stat and (ortho)dynamic amps. why did that B22 go up in smoke?
http://www.youtube.com/watch?v=RUWD-FflZPI

 

[johnwmclean]

 A TRS plug will momentarily short to ground, inserting and disconnecting, not a problem for amps with current limiting, the Beta22 has no current limiting.

 

[daveDerek]

Quote:

 A TRS plug will momentarily short to ground, inserting and disconnecting, not a problem for amps with current limiting, the Beta22 has no current limiting.

 
so is turning the volume down sufficient or are you better off only plugging & unplugging phones when it's powered off?
 
is this the same issue with e-stat amps?

 

[johnwmclean]

Quote:

 
so is turning the volume down sufficient or are you better off only plugging & unplugging phones when it's powered off?
 
is this the same issue with e-stat amps?

 
 
Volume down is sufficient.
 
The stat plug has no such shorting problem. I prefer to turn down the volume, purely as force of habit, and a double measure.