As I know all defects of stability which in Sansui AU-X1 were eliminated in Sansui AU-X11.
It is possible to replace 2SK129A on 2SK146?
I will recommend replacing the black beauty pot due to its age and if it has gang differences please replace it without thinking !
Please desolder the pot check for gang differences it is a must , if this gets wrong you might have to fiddle with power level gain knobs to get a balanced sound stage .
When checking for gang differences please check at various degrees of rotation as well .
Update (Restoration work):
I have finally made another final change to the amp which has brought about a vast difference in its performance . I am now running the amp with power amp knobs fully .
The left and right channels produces accurately the exact same voltage with .differences of around 0.001 between then both !
I found the stage shifting vastly between left and right channels depending on the position of the main volume knob control used for preamp section .
At certain positions of the preamp knob the stage would be centered but at a certain position it would skew a little over to the left or the right .
The issue was diagnosed to the main volume knob Alps black beauty pot .
The gang differences between left and right channels were too huge. Ranging between 500ohms to 1 kohms at a certain position .
This was solved by replacing the black beauty pot itself .
I have made the replacement using ALPS RK27 50KAX2.
The replacement is pretty straight forward with soldering work done on the 6 pin outs .
No chasis cutting is required the Alps RK27 is a direct fit .
Note: please get the genuine RK27 there are lots of fakes floating in the market .
So yes the main preamp control potentiometer is readily available and a easy to do job with no chasis/panel cutting .
View attachment 1399943
I will recommend replacing the black beauty pot due to its age and if it has gang differences please replace it without thinking !
Please desolder the pot check for gang differences it is a must , if this gets wrong you might have to fiddle with power level gain knobs to get a balanced sound stage .
When checking for gang differences please check at various degrees of rotation as well .
Measurements and deviations in gang differences of the removed RK40 will be updated shortly .
On a side note few listening impressions:
The amp brings life to instruments and also the vocals , they sing with lots of emotional touch .
I have been enjoying the journey and am very happy with the amp so far .
It sounds very clean probably the metal film upgrades on driver board have their influence .
Great info.
I've wondered about the linearity of the volume control pot in my X1 so this seems like a good place to ask. When functioning properly, does the Black Beauty (in the X11/X1) normally maintain a flat frequency through out the complete turn or is there a "sweet spot"?
No i have not tried to recondition the volume pot, as it has a lock washer that has to be broken, or cut using a dremel tool to remove the entire pot assembly.Did you try to recondition the original pot through disassembly? If so, although the reconditioning evidently failed to yield the desired result...what were the results?
Late last year I bought an X11 that had a blown driver board.
Here is a picture.
So I am not sure if all X1 problems were solved on the X11.
The X11 was sold in Japan only, so any problems were sequestered to the Japanese market.
So any possible complaints or reports of defect remain in 1980s Japan.
I agree.I'm 100% convinced the stock AU-X11 has significant chances to explode
No, it is well worth spending the money.You suggest not to spend for repair of this amplifier of time and money
No need to do that unless one or more of the major parts are either damaged or missing.it is simple to take it to spare parts?
Nothing done during a proper restoration of an X1 or an X11 is intended to 'slow down' these extremely 'fast' amplifiers. All you should be doing is replacing old components, some of which can become progressively more unreliable with age, some sooner than others - that is the nature of Vintage Restoration.Not to push luck with "bomoby the slowed-down action"?
Take them out and check them with a transistor tester?How it is possible to check transistors regarding constancy of parameters?
I've said it here and there before, but I think it is worth mentioning again... I'm with Ronito on this. We have to stop this wive's tail that the X11 fixed all of the issues of the X1. Also, I'm not 100% convinced it is a stability issue and nobody has ever truly dug into that either (not saying it's no instability, just dislike stating rumour as fact).
Whether it's stability, blackflags (have yet to see one gone bad), or just transistors or design pushed to the edge, I don't know, but I have six AU-X11 drivers board that look like Ronito's. 3 out of 4 AU-X11s I purchased came with blown driver boards. Let's stop with this "AU-X11 fixed issues of AU-X1" talk. This is not to say nothing was addressed with the update, but I'm 100% convinced the stock AU-X11 has significant chances to explode