The Stax Thread III

[kevin gilmore]

maybe the next version of the verto will chuck the music driven bias and the improper loading of the transformer
that attempts to control the ringing. And then it will be just like a srd7

first version of the electrostatic circlotron actually works and no flying parts. There is some output
stage crossover distortion due to me running at a 1ma bias, which i will change later.

Not sure that many of the diyers will like the 4 x 1000V floating output stage power supplies plus
2 x 500V and 2 x15 supplies.

circlotrons move the amplifier complexity from the amp to the power supply.

 

[Currawong]

So are you going to post details of your electrostatic circlotron in the DIY forum here once it is ready?

 

[kevin gilmore]

here is the preliminary amp schematic.
http://gilmore.chem.northwestern.edu/kgsshvcirc.pdf

I'm definitely going to change the output stage bias to the
nelson pass opto isolator thing.

there is no power supply schematic yet.


i have not started on the boards yet either and this
is definitely going to be a 2 box thing.

all current version boards and some schematics (its a work in progress) here
http://gilmore.chem.northwestern.edu/boards/

 

[n3rdling]

  All that talk on a modded 727 sounding nice... decisions decisions.

You should definitely do it if you have one.  It's a really easy mod.

 

[jcx]

Circlotron is different, but is it a win when the 4 output Q you save cost <$4 each
 
I'd guess you end up spending more on the custom xmfr(s?) for the floating supplies
 
do mind the pri-sec, sec-sec winding coupling - shield reduces noise coupling but adds C   - like to see what Mister uV supply noise does with this

 

[Ra97oR]

 

  All that talk on a modded 727 sounding nice... decisions decisions.

You should definitely do it if you have one.  It's a really easy mod.

Running a modded 404 on it, quite happy with it. I listen to music quite quiet most the time. It's a JP ver 727A, should be the same internal right?
 
Shame that I haven't heard a modded one against it, no idea what I am going to get after the mod.
 
Warranty is still active. =/

 

[blackads]

Running a modded 404 on it, quite happy with it. I listen to music quite quiet most the time. It's a JP ver 727A, should be the same internal right?

Shame that I haven't heard a modded one against it, no idea what I am going to get after the mod.

Warranty is still active. =/

Ive modded my 727a, the mod is identical, and very straightforward, just unsolder the end of the relevant resistors which is closest to the card edge connector, levering up slightly with a thin bladed screwdriver while you unsolder, then solder resistor lead to the free end of the resistor and solder the other end to the relevant edge connector. Put a bit of insulating tape under each so it doesnt short and you are done.

I had my 727a for two weeks unmodded, it sounded just plain weird, with a vague and hollowish sound and little bass. After the mod there is an appreciable bass increase and a clear improvement. Ive rebiased and reset dc offset after the mod, as I read a spritzer post which suggested this should be done.

Had the amp for a few months now and it is no slouch, yes I want a bhse or kgsshv, but Im not feeling I HAVE to upgrade, current sound with 009s is incredibly good...

 

[astrostar59]

Wow, it sound very radical. Kevin, what is the design strategy of the new amp? Is it a different direction to get a T2 kind of amplifier without the heat issues?
And do you think it will be up there as regards sound quality?
 
Complexity of build and parts cost would be the main brake for most DIY'er maybe. I was too scared to do my own build of the KGSShv, but plenty of others have tried and had success. The KGSShv parts tally and off the shelf case was about a fifth of the cost of a BHSE for example.

 

[Sweden]

What's the cheapest you guys have seen a used SR-009 sell for? (Japan and Korea included)
I'm having a big itch. 

 

[astrostar59]

I haven't seen many at all. It seems most hang on to them as they are the best headphone in the world IMO.
Good luck with your search. I would recommend buying new myself, you won't regret owning this phone, as long as you have a decent front end.

 

[kothganesh]

  I haven't seen many at all. It seems most hang on to them as they are the best headphone in the world IMO.
Good luck with your search. I would recommend buying new myself, you won't regret owning this phone, as long as you have a decent front end.

I was very lucky with the 009. I traded for it on this forum for my Audez'e LCD 3. Price came down considerably...Listening to it now with my KGSShv and Boston playing...don't get any better than this...

 

[arturo71]

I want one cyclotron under my garden

 

[kevin gilmore]

  Circlotron is different, but is it a win when the 4 output Q you save cost <$4 each
 
I'd guess you end up spending more on the custom xmfr(s?) for the floating supplies
 
do mind the pri-sec, sec-sec winding coupling - shield reduces noise coupling but adds C   - like to see what Mister uV supply noise does with this

 
This has nothing to do with money. Nothing I do is cost effective.
 
This is like timepieces.  There are timepieces, complicated timepieces, and grand complications.
 
This thing is a grand complication. Just like the diy T2.
 
Yes the transformers are a significant issue, and run of the mill stuff is going to arcy-sparky across
the secondary to the primary. This will require transformers that have 4KV wire and isolation.
 
And I won't be doing microvolt noise 1000V power supplies. Just not possible with today's parts.
Simple one stage zener feeding a Sic fet.

 

[bearFNF]

What's the cheapest you guys have seen a used SR-009 sell for? (Japan and Korea included)
I'm having a big itch. 

$3600 from a head-fi member.

 

[Jones Bob]

FYI... a new SR-009 is US$3259 delivered to US on Price Japan's current website.