The Stax Thread III

[DefQon]

For 202/207 owners, what's a good music to let these show it's best?

 

[spritzer]

Quote:

All right, I've got an SRM-T1 now (had it since Friday), and I've tried to dig up as much info as I can, though search engines are giving me a lot of useless results.
 
Is there anything in particular I'd need to know about it? As far as I can tell, it sounds perfectly fine (no hum or hiss, no imbalance), but this being Head-Fi and all, people like to go the extra mile and mod these Stax amps.
 
-The rebiasing procedure has been posted a few times here and elsewhere. I'll need to refer to this if changing tubes or just want to ensure the amp's working as intended.
-A full electrolytic capacitor replacement for amps that old is commonly advised, but what caps should be used in their place?
-The T1 can be modified to accept ECC99 tubes and basically become an SRM-600 as a result, but what's the benefit of this over the stock 6GC7s? Is it enough of an upgrade that it'll suddenly make this thing SR-007-worthy, or will that simply not happen until getting into KGSSHV and BHSE territory?

 
There are no caps in the signal path in this Stax amp and just replace the electrolytic with what ever fits.  Modern caps are much smaller though so you can fit a larger capacitance in the same spot. 
 
It's always a good idea to check the biasing as amps drift with time, especially tube amps. 
 
The ECC99 can handle more voltage and power than the 6CG7.  It makes the amp behave better at higher volume levels but it is not some magic bullet.

 

[Oingo Boingo]

Quote:

I assume that is the full voltage swing per tube then so 530Vp-p? 

 
[size=medium]The above doesn’t take into account the DIY auto-transformers which almost double the swing (can be seen on previous pics).  The dynamics are also raised by extended power supply.  If there would have been any concerns re voltage swing, we could easily use the tubes with e.g. 2000V on anode like the ones on the pic (it’s one of Dmitry’s recent amps, the PU comes separate):  [/size]
 
[size=medium][/size]
 
[size=medium] [/size]

 

[StubKidDtd2512]

Well I knew about head-fi almost 2 years ago but I've just officially created my first account so firstly I want to say Hello to all.
 
I've been doing some research about Stax's headphones (especially about the 009s) and their amps but I couldn't really find any useful information to me, so please help me on this. Currently I'm using the 009s with the Benchmark DAC2 HCG and the SRM-323s. While I do enjoy its midrange so much, I still want a little bit more bass slam. I'm not an engineer but I guess this is because the SRM-323s cant provide enough power for the 009s right? So I've been struggling to find out which current Stax amp would be the best for my taste to use with the 009s besides others options like KGSSHV or LL, because I guess my room will be too hot and cramped for a tube amp like the BHSE or WES.
 
So now there are two paths that I can choose:
 
1. Go with a higher-tier Stax amp like the 727 or 007t. After reading many impressions and reviews about these 2 amps I've come to conclusion that the 727 may be better for me. However here is the problem. Spritzer says that while the stock 727 is more powerful than the 323S, it's not as neutral as the 323S because of its rolled off treble and boosted bass. This can be fixed by doing some mods though. So the questions are: Would the treble be sacrificed too much and would the bass be louder than the 323S say only about 3 dB while still maintaining the 323S' speed if I went with the stock 727? Or if I wanted to have it modded, would it just become a "higher quality" 323S or not?
 
2. Spend every last dollar of my savings on the KGSSHV. I have an acquaintance who has been building a lot of hi-end headphone amps included my balance B22 so I can ask him to build a KGSSHV for me. Of course I know that it is obviously superior to those 2 Stax amps above; however is it truly worth the extra money or not? I just want to save as much money as I could since currently I'm just a college student. My favorite setup is DAC2 HCG ---> balanced B22 ----> HD800 and this hurt my wallet a bit too much. Right now I still wonder if buying the 009s was a bad idea after all. 

 
3. Well this may be not actually an option; however I did read somewhere that Stax is currently working on an exclusive amp for the 009s. Should I just wait until it comes out? Just because I still prefer a commercial amp to a DIYed one, it may create a sort of hard-to-explain feeling you know. 

 
Thanks in advance and sorry for my English.

 

[wink]

I think any new Stax amp for the 009 would be a heap more expensive than a KGSSHV or even a BHSE.....

 

[eric65]

Hello Stubkid, we will compare the 7 and 8 September, with Frederick, Peter and me, four amplifiers on the headphone Stax SR-009 : amplifiers SRM 727, SRM 007t2;  Eddie Curent Electra and combi Audiovalve RKV + Audio energizeur Woo Wee.
We will tell you soon who will seem for us the best or have the best synergy with the Stax 009 listening.
 
In all cases, these amplifiers should go further than the SRM 323 already listened and compared against all these amplifiers (by Peter and Frederic)
 
Eric
 
PS: these comparisons amplifiers will be made in ​​blind test on 7 and 8 September, following a rigorous testing protocol. 
The test results will be published during September, in first in the French forum HCFR on Stax, at this link :
http://www.homecinema-fr.com/forum/casques-haute-fidelite/club-des-heureux-proprietaires-de-casques-stax-t29819561-4740.html

 

[Trance_Gott]

I already have a SR307 in combination with SRM1 MK2. Now I have a chance to buy a Lambda Pro or 404LE. Is it worth to upgrade from SR307? What can Lambda Pro or 404LE better as my SR307?

 

[Ali-Pacha]

Hi Stax addicts,
 
I've a problem on my SR-X/mk3 (normal bias) since at least 10 years...never tried to fix it, since I regularly use my SR-5 out of the same SRD-7/SB transformer.
I've a lot of crackles at low level, on both sides, and it's getting worst when touching the cable.
Here is a sample (low quality, using my phone) : 
 
http://alipacha.free.fr/SR-X_Mk3_Problem.mp3
 
Very noticeable at 00:13
I've very carefully opened one of the driver, there's no hole(s) in there. Same behavior when I re-assemble it.
It seems to come from the cable, as a guy on another forum has the same issue withe same cans, fixed by re-cabling. And I don't want to touch the cooper of the cable inside the earspeaker when running.
 
Did anyone meet this issue ?
 
Thxx
 
Ali

 

[DefQon]

Quote:

Hi Stax addicts,
 
I've a problem on my SR-X/mk3 (normal bias) since at least 10 years...never tried to fix it, since I regularly use my SR-5 out of the same SRD-7/SB transformer.
I've a lot of crackles at low level, on both sides, and it's getting worst when touching the cable.
Here is a sample (low quality, using my phone) : 
 
http://alipacha.free.fr/SR-X_Mk3_Problem.mp3
 
Very noticeable at 00:13
I've very carefully opened one of the driver, there's no hole(s) in there. Same behavior when I re-assemble it.
It seems to come from the cable, as a guy on another forum has the same issue withe same cans, fixed by re-cabling. And I don't want to touch the cooper of the cable inside the earspeaker when running.
 
Did anyone meet this issue ?
 
Thxx
 
Ali

I had this same problem with my old Lambda Pro's where there is intermittent crackling and no sound if I wiggled a particular area of the cable. Replaced the cable and it was fine.

 

[livewire]

Quote:

For 202/207 owners, what's a good music to let these show it's best?

Hmmm, they let you back in the Stax thread??? LOL (j/k)
 
With my 202 rig Infected Mushroom - "Becoming Insane" does the trick for me.
I also like Pink Floyd - "Wish you Were Here".
Sounds awesome, although the vocals suffer a bit due to the 202's flawed mids.

 

[DefQon]

Hmmm, they let you back in the Stax thread??? LOL (j/k)

With my 202 rig Infected Mushroom - "Becoming Insane" does the trick for me.
I also like Pink Floyd - "Wish you Were Here".
Sounds awesome, although the vocals suffer a bit due to the 202's flawed mids.

What do you mean? I was never banned from the Stax thread.

Anywho thanks.

 

[livewire]

Re: 202 sounding it's best: (classical sound with synthesizer overtones )  Vangelis - Main Theme From "Missing" 
 
And another Vangelis classic with a Japanese theme: "The Tao Of Love". 
 
Check em out on youtube, although CD quality / FLAC sounds superb.

 

[oogabooga]

Antonyfirst, any word on those photos and details of the mods? Also, how do you find the sound signature after a few weeks more of listening? Any changes?  Apologies if you've posted this elsewhere already.
 
 
Quote:

So, I have modified my SRM-727A after KG's advice. I had formerly modded the amp with the "spritzer" mod (by changing local feedback to global), but Kevin helped me making the modification much more radical.
Basically, we fixed his 727 schematic together (I provided pictures eheheh) in order to have a complete idea of how to overhaul the output stage and make it better.
He gave me instructions to replace 10 transistors on the board a few resistors with eight pieces of 2sc4686a (or 2sc4686) transistors (the same as the KGSSHV) and some shorts. I will post the instructions here after Kevin's permission.

The result is a 727A that not only has its feedback 'restored', but also the same identical output stage of the KGSSHV. My 727A (which I rebaptised "KGSS-A") is basically a KGSS with current source modification (which was the "better" part of the feedback modded 727 over the 717), and better (faster, more modern) transistors than the older KGSS.
Or, the other way around, this modified 727 is a KGSSHV minus the higher voltage, since there was no room for a better PSU.

The sound has improved in transparency and overall extension. The bass has more control and the treble is smoother. I am using a SR-007 Mk1 and a SR-Lambda (the latter, after modifying another output after KG's advice).

Also, really interesting, the newer transistors get much less hot. My 727A is barely hot now, even after much time of usage, while the 717 I used to have, the older version 727 and even the SRM-Mk2 Pro I used to have here ago used to run noticeably hotter. I guess it depends on the newer transistors being capable of handling much higher voltage than what I am squeezing from the 727A psu, hence having very good efficiency.

I can take some dirty pictures, and will be waiting for Kevin's blessing to post the mods.

 

[StubKidDtd2512]

Thanks for your replies!
Quote:

I think any new Stax amp for the 009 would be a heap more expensive than a KGSSHV or even a BHSE.....

... that's why I said it's not really an option for me to consider. I'm afraid that even funding for a BHSE is impossible for at least 3 years from now...
 

Hello Stubkid, we will compare the 7 and 8 September, with Frederick, Peter and me, four amplifiers on the headphone Stax SR-009 : amplifiers SRM 727, SRM 007t2;  Eddie Curent Electra and combi Audiovalve RKV + Audio energizeur Woo Wee.
We will tell you soon who will seem for us the best or have the best synergy with the Stax 009 listening.
 
In all cases, these amplifiers should go further than the SRM 323 already listened and compared against all these amplifiers (by Peter and Frederic)
 
Eric
 
PS: these comparisons amplifiers will be made in ​​blind test on 7 and 8 September, following a rigorous testing protocol. 
The test results will be published during September, in first in the French forum HCFR on Stax, at this link :
http://www.homecinema-fr.com/forum/casques-haute-fidelite/club-des-heureux-proprietaires-de-casques-stax-t29819561-4740.html

Hello Eric, I read about this in the amps for the 009 thread a few days ago and I'm really looking forward to hearing the result. However it would be nice if that 727 was a modded one.

 

[spritzer]

Quote:

 
[size=medium]The above doesn’t take into account the DIY auto-transformers which almost double the swing (can be seen on previous pics).  The dynamics are also raised by extended power supply.  If there would have been any concerns re voltage swing, we could easily use the tubes with e.g. 2000V on anode like the ones on the pic (it’s one of Dmitry’s recent amps, the PU comes separate):  [/size]
 
[size=medium][/size]
 
[size=medium] [/size]

 
The problem here and the main reason why something like the KGSSHV/T2 can swing about 2000Vp-p is to make sure the amp never has to swing at max level.  That's where it is most unlinear and a lot of distortion occurs. 
 
Sennheiser had to learn this the hard way, well their customers did as so many HEV90 as basically defective.  The first amps can just muster about 500Vp-p butt ended at 1200Vp-p for the last version.  Just internal changes and same tubes used all along.