Caution: Electrostatic amp compatibility (HE90 owners in particular)

[Xanadu777]

Justin has sent me a pic with instructions on how to adjust/change bias voltage on KGSS to 500V.

What's not clear to me are a couple of things. I am assuming a stock KGSS has the 5M resistor also, does it? Should I change this to 10M for HE90's (assume yes)? Do either of those resistors, if they are present, change the voltage at the jack?

 

[Hirsch]

Quote:

Originally Posted by Xanadu777 Justin has sent me a pic with instructions on how to adjust/change bias voltage on KGSS to 500V. What's not clear to me are a couple of things. I am assuming a stock KGSS has the 5M resistor also, does it? Should I change this to 10M for HE90's (assume yes)? Do either of those resistors, if they are present, change the voltage at the jack?

Yes, the resistor should be changed to 10 M for the HE90 (or simply put a 5 M resistor in the bias line of your Stax to HE90 adapter, if you're going to be using one). This does not alter the bias voltage.

 

[braillediver]

What are the tubes used in the Headamp Electrostatic amp?

What were the tubes used in the Orpheus amp?

I'm late to the barbeque but curious.


Mitch

 

[Hirsch]

Quote:

Originally Posted by braillediver What are the tubes used in the Headamp Electrostatic amp? What were the tubes used in the Orpheus amp?

Both amps use a pair of 12AX7's and a quad of ECL86's.

 

[Wmcmanus]

Quote:

Originally Posted by kevin gilmore I've been informed that the use of the word "clone" around here brings up some nasty and bad history. This is not the equivalent of a RA-1 clone, not even close. In fact the circuitry goes back to the early 1960's.

Maybe that is because the word "clone" implies that all one has done is to reverse engineer the design, and thus effectively steal another company's intellectual property which, in the case of the HEV90, is undoubtedly protected by a design patent. From your description, it doesn't seem like your HEV90 equivalent will be a clone.

 

[mikeg]

Do design patents expire after a certain number of years? Do you think that the HEV90's design patent is still "valid"?

Quote:

Originally Posted by Wmcmanus Maybe that is because the word "clone" implies that all one has done is to reverse engineer the design, and thus effectively steal another company's intellectual property which, in the case of the HEV90, is undoubtedly protected by a design patent. From your description, it doesn't seem like your HEV90 equivalent will be a clone.

 

[PATB]

Quote:

Originally Posted by mikeg Do design patents expire after a certain number of years? Do you think that the HEV90's design patent is still "valid"?

I am not giving legal advice. But here it goes anyways.

In the United States, design patents only apply to the "looks" of the patented device. In this case, the Aristaeus, Justin's amp, does not look anything remotely close to the HEV90. In any case, design patents last 14 years from issue.

In the United States, utilitiy patents cover the "functionality" of the device. In this case, the Aristeaus may or may not have the same circuit covered under one of Senheisser's US patents. A utility patent lasts 20 years from the priority date, which is the filing date in most (but not all) cases. Sennheiser only has 28 utility patents in the United States, so it may not be too difficult for someone with knowledge of the Aristaeus to go through them.

 

[kevin gilmore]

quote
From your description, it doesn't seem like your HEV90 equivalent will be a clone.

Let me make this absolutely clear. I had absolutely nothing to do with the
design of the aristeaus. This is 100% justin wilson's work. And he put
a huge amount of work into it. The circuit boards are fantastic and
have a lot less noise than the original. Far more rigid. The power supply
is significantly different and massive to say the least and being linear
there is no switching noise. The parts quality is far superior to and more
stable than the original.

This design is based on a "composite low distortion" amplifier designed
by rca engineers in the late 1950's. It uses 3 such amplifiers. Exactly
the same as the hev90. The result is a tube amplifier with very large
voltage swings and a distortion of less than .02%. I did a patent
search a while back, and was unable to find anything relating to this.
But if there was such a patent it would have long since expired.

For those people lucky enough to purchase the last batch of he90
headphones they need an amplifier to plug them into. New hev90's
are not available. And are unlikely to ever be available again. Stax
amps?? Not something most people are interested in. The
Aristaeus is not only the next best thing, it is better than the
original. And it will drive stax headphones too if that is your desire.

Yes i bought a pair of boards from justin. Yes i have a working unit
that is currently waiting for the final chassis. Its absolutely a first
rate world class product.

 

[immtbiker]

It would be nice to have a HEV-90 option...especially if it sounds equally as good, if not better, and costs half the Orpheus' price.
Just as long as no one is getting hurt, and no laws, both legally and morally, are broken.
Why have an HE-90, if you don't have an amp that compliments it? House/foundation/weakest link theory.

 

[Guss2]

Thanks for the insight Kevin,this just makes the wait that much more difficult

.Gary.

 

[rickcr42]

I for one find it just a bit interesting that an amp formerly considered a POS and way overpriced "flash" is suddenly considered world class with a simple R/C and power supply upgrade.
The solens are a good cap for the price but hardly the last word in resolution and metal films not a be all end all either when the well known proclivity towards hardness of some versions is added.It is more selective to position in circuit than it is generic "metal film" that counts.
That this amp sounds good overall I have little doubt considering I always thought the original to sound just fine,very free and easy sounding, but I have to wonder how this jibes with the former "it sucks" attitude on this amp here at head-fi.
It seems to me only products offered by the original company suck and get bashed openly while our little brand of "in house mods" or "cloning" are considered world class amps.I personally find this very unsettling and it says a lot about certain people who have no trouble "flipping" opinions when it serves to do so.

'Nuff by me on this,proceed

 

[Canman]

I don't what used to be but lately most accounts of the HEV-90 are excellent, if not sublime. I think it sounds great. The HEV-70 on the other hand...not that good.

I think the Rickmeister's comment is more applicable to the Stax amps like the 007t, which happens to be very nice.

Quote:

Originally Posted by rickcr42 I for one find it just a bit interesting that an amp formerly considered a POS and way overpriced "flash" is suddenly considered world class with a simple R/C and power supply upgrade.

 

[eric343]

Rick,
What are you talking about?

KG on the Orpheus (http://headwize.com/projects/showfil...more_prj.htm): "A wonderful system, although the inboard D/A converter is awful. Otherwise excellent."

Mike Walker (http://headwize.com/ubb/showpage.php...53&srch=hev90;) : I've heard them only at a friend's house. They're simply amazing...with all the clarity that electrostats are known for, but with a superbly warm "full" bass (some elctrostats seem kind of tilted toward the highs. Not these). The amp, of course, is a thing of beauty.

Cmoy (http://headwize.com/ubb/showpage.php...s;amplifier: Although the Orpheus has gotten consistently good reviews, the HE60/HEV70 has gotten a mixed reception.

And me (http://www6.head-fi.org/forums/showthread.php?t=82972): "The HEV90 is better than I'd remembered it from my auditioning at WoH Tour, Winlock, and Magnolia Hi-Fi. "Tubes done right" if you will. Almost the detail of the KGSS, a nice warm tubey touch, and enough bass to get the HE90s rockin'. [...] That said, overall the HEV90 won out. The KGSS definitely has more detail and midrange clarity; on pieces like Strauss' Banditen Galop the texture of the gunshots (yep, Wayne, you were right, they're definitely gunshots - the initial pressure followed by the decay is almost exactly the same as a cap-gun I have.) is much more audible. At the same time, however, the increased bass response (the KGSS seems to totally lack bass at the moment. I suspect the HE90s still need charging) and smooth, warm texture of the HEV90 really works well with the HE90s. Art Pepper Meets the Rhythm Section just sounds more real with the HEV90. Like most all-tube designs that I've heard, the HEV90 rounds off the edginess in the music, but does it just enough to make everything sound good. It really is an excellent example of Tubes Done Right. Compared to the Blue Hawaiis that I've heard, the HEV90 has even more, if slightly sloppier, bass and is a true Tube Amp in sound."

And so on and so forth. The only negative comments about the Orpheus amplifier relate either to the DAC stage (a fairly common complaint) or the circuit design (KG doesn't like tetro-err, pentodes). And KG's comments were based on the schematic -- once he heard it, things changed a little.

 

[eric343]

Quote:

Originally Posted by PATB I am not giving legal advice. But here it goes anyways. In the United States, design patents only apply to the "looks" of the patented device. In this case, the Aristaeus, Justin's amp, does not look anything remotely close to the HEV90. In any case, design patents last 14 years from issue. In the United States, utilitiy patents cover the "functionality" of the device. In this case, the Aristeaus may or may not have the same circuit covered under one of Senheisser's US patents. A utility patent lasts 20 years from the priority date, which is the filing date in most (but not all) cases. Sennheiser only has 28 utility patents in the United States, so it may not be too difficult for someone with knowledge of the Aristaeus to go through them.

None of those patents cover anything like a headphone amplifier, much less for the Orpheus headphones. The only Orpheus patent covers an electrostatic headphone with the membrane arranged at an angle to the housing...

 

[kevin gilmore]

The ecl86 is a pentode. There are things about pentodes that i still
do not like to this day. They really don't belong in audio when there are
so many other better alternatives.

Now beam power tetrodes are a different thing entirely as they
are the only way to get large amounts of power without having to
stack a huge pile of tubes.