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The Stax Thread III - Page 234

post #3496 of 11932
Quote:
Originally Posted by eric65 View Post

 

See also : http://www.head-fi.org/t/727055/diy-tube-amp-for-electrostats-transformer-coupling-vs-dc-coupling#post_10730457

 

 

Hello FranckCooter, 

 

Your publications (rare) are highly appreciated for their quality and pedagogy. 

 

You explain unprejudiced the advantages and disadvantages of electrostatic headphone amplifiers using transformers step up behind a tube amplifier operating in OTL mode. 

 

If I understand correctly, the theoretical performance of such an amplifier (with transformers step up) will always priori inferior to those of direct-coupled amplifiers do not use output transformers

 

Yours.

 

Eric

 



While I appreciate your complement, there's a little misunderstanding going on here that is probably my fault. The transformer-coupled topology I was referring to (and use myself) is not the type employed by the Stax,Woo, or Verto boxes, where a low voltage, low impedance speaker level signal is stepped up to electrostatic headphone levels via an additional high winding ratio transformer. The transformers I use are very much like any other tube amp output transformer, except that the secondary winding is wound for a 1:1-1 ratio. Unlike Stax-type boxes, the high impedance of the amplifier output transformer primary is preserved, and there is no voltage step-up at all. All amplification is via the tubes, and the headphones are driven directly off the secondary of the amplifier output transformer.

Having never heard any transformer boxes except for the Stax, I'm not really qualified to render an opinion on them. I will say that the lower the winding ratio, the better the chance to build a quality unit. In a high level signal transformer such we're talking about here, as step-up increases, so does stray capacitance. The greater the stray capacitance, the greater the high frequency roll off. If you cut the primary turns to decrease the number of required secondary turns, you decrease the bass. A 1:5 step-up sounds a lot more promising than 1:50.
Edited by FrankCooter - 10/28/14 at 6:09pm
post #3497 of 11932
Quote:
Originally Posted by FrankCooter View Post

Quote:
Originally Posted by eric65 View Post

 

See also : http://www.head-fi.org/t/727055/diy-tube-amp-for-electrostats-transformer-coupling-vs-dc-coupling#post_10730457

 

 

Hello FranckCooter, 

 

Your publications (rare) are highly appreciated for their quality and pedagogy. 

 

You explain unprejudiced the advantages and disadvantages of electrostatic headphone amplifiers using transformers step up behind a tube amplifier operating in OTL mode. 

 

If I understand correctly, the theoretical performance of such an amplifier (with transformers step up) will always priori inferior to those of direct-coupled amplifiers do not use output transformers

 

Yours.

 

Eric

 



While I appreciate your complement, there's a little misunderstanding going on here that is probably my fault. The transformer-coupled topology I was referring to (and use myself) is not the type employed by the Stax,Woo, or Verto boxes, where a low voltage, low impedance speaker level signal is stepped up to electrostatic headphone levels via an additional high winding ratio transformer. The transformers I use are very much like any other tube amp output transformer, except that the secondary winding is wound for a 1:1-1 ratio. Unlike Stax-type boxes, the high impedance of the amplifier output transformer primary is preserved, and there is no voltage step-up at all. All amplification is via the tubes, and the headphones are driven directly off the secondary of the amplifier output transformer.

Having never heard any transformer boxes except for the Stax, I'm not really qualified to render an opinion on them. I will say that the lower the winding ratio, the better the chance to build a quality unit. In a high level signal transformer such we're talking about here, as step-up increases, so does stray capacitance. The greater the stray capacitance, the greater the high frequency roll off. If you cut the primary turns to decrease the number of required secondary turns, you decrease the bass. A 1:5 step-up sounds a lot more promising than 1:50.

You mean Eric cannot leverage your ever more amazing diy work to help push his verto business? Now that's unfortunate.
Arnaud
post #3498 of 11932

Hi, sorry for high-jacking the thread. I am going to try custom molds on my SR-003, and I was wondering if someone has already try that.

In my understanding, the custom earmold shouldn't be too deep, since "air passage" might otherwise become too tight compared to how the 003 output the sound (they normally have a large nozzle and wide tips, compared to regular in-ears).

 

I was wondering if anyone could give me some advice: ideally, I like the sound better when they are used without the headband (with the headband, the midbass is more abundant and the drivers are farther from the ear).

From a sonic point of view, the only real limitation of the SR-003 (with standard tips) is the lack of deep bass. I'd like to achieve this with custom tips, without screwing the rest of the tonal balance, nor making them dark (like it happens, instead, with the tips that Stax put out lately, which resemble more those of a Sony iem).

Any clues?

I have already taken the ear canal impressions, so I only need to decide on depth before taking the plunge.

post #3499 of 11932
Quote:
Originally Posted by kevin gilmore View Post
 

a fully symmetric,complementary and differential electrostatic amp is possible.

you need a pile of 2sa1968's and a pile of 2sc4686a's. You have to limit

the power supplies to +/-450V.  and you need a fancy floating output stage

control circuit to exactly control the output stage bias.  Think something

along the lines of the computer that controls the Ragnarok.

 

you will blow up lots of parts before you get the bias control exactly right.

Maybe when Jason has nothing else to do for a few weeks.

 

Don't forget the "Carbon"    (kgst with silicon carbide fets as the output stage)

 

and "NanoTube"   (Silicon Carbide Circlotron)

 

I have at least one each of diyt2,kgsshv,kgst,kgss,bh,bhse,ges,es1,megatron and probably a few more

that I forgot.

 

its really hard to figure out which amp/headphone to listen to every day.

Thank Kevin for this clarification.

Therefore build a fully symeterique electrostatic amp this is forego most of the qualities they have when they are not fully symeterique.

Thank at you Kevin, Franck and Michgelsen for helping me to better understand : )

post #3500 of 11932
Quote:
Originally Posted by FrankCooter View Post
 
Quote:
Originally Posted by eric65 View Post
 

 

See also : http://www.head-fi.org/t/727055/diy-tube-amp-for-electrostats-transformer-coupling-vs-dc-coupling#post_10730457

 

 

Hello FranckCooter, 

 

Your publications (rare) are highly appreciated for their quality and pedagogy. 

 

You explain unprejudiced the advantages and disadvantages of electrostatic headphone amplifiers using transformers step up behind a tube amplifier operating in OTL mode. 

 

If I understand correctly, the theoretical performance of such an amplifier (with transformers step up) will always priori inferior to those of direct-coupled amplifiers do not use output transformers

 

Yours.

 

Eric

 



While I appreciate your complement, there's a little misunderstanding going on here that is probably my fault. The transformer-coupled topology I was referring to (and use myself) is not the type employed by the Stax,Woo, or Verto boxes, where a low voltage, low impedance speaker level signal is stepped up to electrostatic headphone levels via an additional high winding ratio transformer. The transformers I use are very much like any other tube amp output transformer, except that the secondary winding is wound for a 1:1-1 ratio. Unlike Stax-type boxes, the high impedance of the amplifier output transformer primary is preserved, and there is no voltage step-up at all. All amplification is via the tubes, and the headphones are driven directly off the secondary of the amplifier output transformer.

Having never heard any transformer boxes except for the Stax, I'm not really qualified to render an opinion on them. I will say that the lower the winding ratio, the better the chance to build a quality unit. In a high level signal transformer such we're talking about here, as step-up increases, so does stray capacitance. The greater the stray capacitance, the greater the high frequency roll off. If you cut the primary turns to decrease the number of required secondary turns, you decrease the bass. A 1:5 step-up sounds a lot more promising than 1:50.

 

Thank you very much for these latest information, very clear.

post #3501 of 11932
Quote:
Originally Posted by antonyfirst View Post

Hi, sorry for high-jacking the thread. I am going to try custom molds on my SR-003, and I was wondering if someone has already try that.
In my understanding, the custom earmold shouldn't be too deep, since "air passage" might otherwise become too tight compared to how the 003 output the sound (they normally have a large nozzle and wide tips, compared to regular in-ears).

I was wondering if anyone could give me some advice: ideally, I like the sound better when they are used without the headband (with the headband, the midbass is more abundant and the drivers are farther from the ear).
From a sonic point of view, the only real limitation of the SR-003 (with standard tips) is the lack of deep bass. I'd like to achieve this with custom tips, without screwing the rest of the tonal balance, nor making them dark (like it happens, instead, with the tips that Stax put out lately, which resemble more those of a Sony iem).
Any clues?
I have already taken the ear canal impressions, so I only need to decide on depth before taking the plunge.
I have read about this kind of customization a year back or so. I believe the OP relied on sensaphonics custom molds.

More recently, it may have been Tyll at inner-fidelity who interviewed Stax US distributor (ces 2014 maybe) where he mentionned that custom molds were coming for the stax iems. Or I have dreamed and it was only a remodeling of the ear tip.

Anyhow, adding silicon shells has been done, I have read it here, maybe you can do a search on the stax model number + sensaphonics, it should come up...

Arnaud
post #3502 of 11932

Hi all, Hi n3rdling : ) 

 

That's it, 
I have my X1T : D

 

What to say except that often we think to have the best, but there have always better, he surpasses the Stax Dac Talent BD with update IVC 01 and of far: $ 
it makes a bit more tribute to my Omega in pending SRM T2 ( I must take absolutely the SRM T2, seen the good quality that brought me the X1T ) 

 

 

Here are some pictures : )

 

Warning: Spoiler! (Click to show)

 

 

 


Edited by Jonathan66100 - 10/29/14 at 10:03am
post #3503 of 11932
Hm I am thinking about this custom sleeves for 003 for a while, but the experiences here on headfi where mixed.

Anyway I view the 003 and 003 MK2 as the 2 most underrated headphones by Stax. On a good amp I prefer them tonaly to any Lambda- the deep bass is stunning. But the reason could be my ears are compatible.
post #3504 of 11932
Congratulations,
I'm still looking for a X1t and a ca-x pro

Regards Georg

PS: i can swap a CA-Y, SRA14S with extra cards or Even a SRA 12S
post #3505 of 11932

Congrats Jonathan! :D  Pretty amazing sound, right?

post #3506 of 11932

Thank you Mike : )

 

Incredible sound xD

I would do a little more precise report when I would have time:)

But now I anyway have to go at  bed: /

It's late in France xD

 

PS : sorry Georg : / i keep the mine and for long time :$

I sincerely wish you to find one one day. it's hard but it's possible !


Edited by Jonathan66100 - 10/29/14 at 6:09pm
post #3507 of 11932
Quote:
Originally Posted by FrankCooter View Post

While I appreciate your complement, there's a little misunderstanding going on here that is probably my fault. The transformer-coupled topology I was referring to (and use myself) is not the type employed by the Stax,Woo, or Verto boxes, where a low voltage, low impedance speaker level signal is stepped up to electrostatic headphone levels via an additional high winding ratio transformer. The transformers I use are very much like any other tube amp output transformer, except that the secondary winding is wound for a 1:1-1 ratio. Unlike Stax-type boxes, the high impedance of the amplifier output transformer primary is preserved, and there is no voltage step-up at all. All amplification is via the tubes, and the headphones are driven directly off the secondary of the amplifier output transformer.

 

I dare a newbie / stupid question : no impact on output impedance, no voltage multiplier...so what are the transformers for ?

Ali
post #3508 of 11932

To isolate from B+, typically 400 to 600 vdc. Otherwise you have to use capacitors

from the plates of the tubes, or lift the bias 580v above the DC voltage.

post #3509 of 11932
Frank whatever became of your 845 amplifier?
post #3510 of 11932

 

 

 

 

                                                                                                     

Quote:
Originally Posted by NoPants View Post

Frank whatever became of your 845 amplifier?

 

It's in daily use. There are still improvements to be made, but I'm pleased with the project.  I'm building a second one for a friend (mock up in lower photo).

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