Sansui AU-X1????

slimecity

Super Member
Hi there - I have read a bit about the oscillation issues present in this amp. If I were to buy one at a reasonable price - if the outputs were blown - would it be fixable? I presume we aren't talking about a "VFET" situation here and the outputs could be replaced with modern equivalents, and appropriate circuit mods also made to make the amp more stable?

The second part of my question will piss some people off - sorry - I love the sound of the earlier sansuis - and am NOT a fan of the later ones. for example, I had an AU-X701 and I did not like it - it was nice and detailed but very clinical and too "sweet" for me. (I prefer that vintage "chunky" sound...!) So how does the AU-X1 SOUND? If I get it, would I be likely to like it?

thanks!
 
Hi there - I have read a bit about the oscillation issues present in this amp. If I were to buy one at a reasonable price - if the outputs were blown - would it be fixable? I presume we aren't talking about a "VFET" situation here and the outputs could be replaced with modern equivalents, and appropriate circuit mods also made to make the amp more stable?

OP transistors blown? - yes it would be fixable, but like all amplifiers with 'fast' output transistors it is said that they lose some of their very fine performance if not equipped with similarly fast replacements. The original output transistors for the AU-X1 are nearly impossible to find. It would be possible to use plastic case replacement transistors, there are some extremely good ones available which will give the amplifier back that lost performance. People have very successfully performed this modification with the AU-X11 and the AU-919 which are also in the same situation regarding OP transistors.

The second part of my question will piss some people off - sorry - I love the sound of the earlier sansuis - and am NOT a fan of the later ones. for example, I had an AU-X701 and I did not like it - it was nice and detailed but very clinical and too "sweet" for me. (I prefer that vintage "chunky" sound...!) So how does the AU-X1 SOUND? If I get it, would I be likely to like it?

thanks!

Given the above, and no, you are not pissing me off at all :D to each his own. I think you would like the AU-X1, as I feel it is more akin to the sound of the AU-919 / AU-x17 series - and less so the AU-X701 / 901 series. I speak as someone who owns an AU-919, AU-X1 and an AU-X701. Remember however that the AU-X1 has no tone controls, (or loudness switch) I haven't felt the lack of them at all when using mine. I can say that the AU-X1 is a very special amplifier, and once it has the appropriate modifications seems as stable as any other Sansui, as far as my experience goes.
 
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OP transistors have, on occasion, been available from a reliable source, an AKer in Croatia, on that auction site but I don't know how long that supply will last. I hope that I am being cryptic enough.

Marc
 
I agree with hyperion at full. You will never feel the need to use tone controls or loudness on AU-X1. It is indeed a very special amp . I feel realy poor in my collection not owing one. Great amp.


As for the outputs of x1 contact member Nicowico he had written sometime about where to find those ones originals.
 
Just putting this out there.....

An X1 with a serial number 219120095 is likely to be an early unit, or a later unit with oscillation issues addressed by Sansui?

Otherwise operating condition is unknown except that its in protect mode.

If in protect mode is this more than likely that some outputs are blown? Or could this possibly be something else....?

Cheers!
 
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Just putting this out there.....

An X1 with a serial number 219120095 is likely to be an early unit, or a later unit with oscillation issues addressed by Sansui?

Otherwise operating condition is unknown except that its in protect mode.

If in protect mode is this more than likely that some outputs are blown? Or could this possibly be something else....?

Cheers!

This is what I know,
Anything can be rebuilt, but it is in the best interest of the intended performance of the amplifier to have the correct output transistors.
The AU-X1 is an extraordinary amplifier, very high speed.
This is part of its sound.

There are several things that can put the X1 into protect mode, certainly blown output transistors is one, but some others are;
Excessive DC offset originating from the pre-amp, as it is a Direct coupled amp, offset in the pre-amp will transpose directly to the output where it will trip the SCR.

The SCR could be faulty, this was one of the faults in the X1 I worked on recently.

There could be one of the fusible resistors in the driver circuit which has gone hiZ

Now, the sound.
The X1 sounds NOTHING like what I thought it would. It simply has the most impressive phono stage I have ever heard.

Some adjectives that come to mind when I think about the sound of the X1.

FAT
SOLID
Pronounced yet smooth mid-range.
Velvet High end.

The bass is very impressive, and at no time did I think I wanted to make a tone adjustment listening to the X1....

If I owned one, I would run it with the top off, just because it looks so COOL!!

IMG_4768.JPG
 
If I owned one, I would run it with the top off, just because it looks so COOL!!
Thanks so much Kev.

I will see how I go with this auction.

Yes I've been researching possible replacement outputs in case some are fried - and I still don't really have a clear picture on that (for high speed equivalents anyway) so I will keep on researching.

Weighing in at a mere 27-odd kilos, it certainly will cost a pretty penny to get shipped to our shores! lol.
 
Thanks so much Kev.

I will see how I go with this auction.

Yes I've been researching possible replacement outputs in case some are fried - and I still don't really have a clear picture on that (for high speed equivalents anyway) so I will keep on researching.

Weighing in at a mere 27-odd kilos, it certainly will cost a pretty penny to get shipped to our shores! lol.
There really isn't an option for high speed output devices except for getting them NOS.
You can fit slower devices, and the amp will work fine, but it could change its sonic signature.

Yeah always a little high on the shipping getting them down here, totally worth it though...

There might be an AU999 coming up for sale locally soon too...
 
e really isn't an option for high speed output devices except for getting them NOS.
You can fit slower devices, and the amp will work fine, but it could change its sonic signature.
Thanks Kev - already have a 999!

Note Hyperions' advice above in the second post.

Looks like if TO-3 originals cant be found then there may be some modern plastic case trannies which could work as high speed subs.

I hope this is the case - I do want to restore to full high-speed operation rather than compromise......
 
Not in English, but you get the idea:
http://www.diyaudio.com.hr/viewtopic.php?f=8&t=706&p=16326&hilit=standardne#p16326
http://www.diyaudio.com.hr/viewtopic.php?p=15715&sid=09ea4d2b914058782700180235e21129#p15715

And some good points from this post and the next few are relevant too:
http://audiokarma.org/forums/index.php?threads/its-dead-jim-au-x1.181689/page-2#post-2102749

Personally, I'm going to use the originals where possible. I have two AU-X11 and enough good output transistors for one unit. One unit will get the original transistors, but when those aren't available, you have to make a choice. Either use the slower TO3 (e.g. MJ21194/MJ21193) which requires no physical mods, or the highspeed TO3p (eg JW0281G/NJW0302G ?), but this needs to be done really carefully (you don't want those legs shorting out on the heatsink!) My plan is to setup one with the original outputs, and one with the slower TO3 and do some listening tests; if I can't hear the difference I wont make the physical mods for the T03p.
 
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or the highspeed TO3p (eg JW0281G/NJW0302G ?)
Cheers Smurfer - this is the kind of info I was hoping would be the case.

Yes I have adapted outputs to different packages before - and if I get the X1 I will be taking extra care with EVERY aspect of it!

My plan is to setup one with the original outputs, and one with the slower TO3 and do some listening tests; if I can't hear the difference I want make the physical mods for the T03p.

It would be great to hear the outcome of this - Im sure many AK'rs would also be keen on this - I have seen other posts in other places where people have just subbed in the 93/94 and still been impressed with the sound. It would be awesome to know how much difference the high speed outputs make in terms of subjective enjoyment of the sound.
 
Thanks Kev - already have a 999!

Note Hyperions' advice above in the second post.

Looks like if TO-3 originals cant be found then there may be some modern plastic case trannies which could work as high speed subs.

I hope this is the case - I do want to restore to full high-speed operation rather than compromise......

You'll find some high speed devices, they are out there, not exactly cheap, but they are around....
 
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