Hipocrates
Super Member
Now THAT sounds interesting
Is the AU-X1 a must have Sansui?
- Thread starter jefferylhenr
- Start date
@Hipocrates, all I really meant by that is the AU-X1 built further on what they had already done with the AU-919. It was a technical improvement on the previous generation of amps (AU-819/919) but not a great enough leap to be considered revolutionary. The one thing that may be said is head and shoulders above the X1's predecessors is it's phono stage
That the X1 was followed by a rather short flirtation with super feedforward, then dropped that in favor of X balanced (which inn turn begat Alpha) means the X1 should logically be considered the tail end of the line started by the AU-717. Admittedly, that is how I perceive the delineation of Sansui's technological eras, so others may disagree.
Edit to add: the AU-X1 was the first integrated by Sansui to dabble in the decidedly "purist" mindset that was starting to coalesce at the time, as evidenced by the omission of any tone controls. It is somewhat notable for that, too. I won't debate the pros and cons of that design approach, but it was certainly a departure from Sansui's normal design practices at the time.
That the X1 was followed by a rather short flirtation with super feedforward, then dropped that in favor of X balanced (which inn turn begat Alpha) means the X1 should logically be considered the tail end of the line started by the AU-717. Admittedly, that is how I perceive the delineation of Sansui's technological eras, so others may disagree.
Edit to add: the AU-X1 was the first integrated by Sansui to dabble in the decidedly "purist" mindset that was starting to coalesce at the time, as evidenced by the omission of any tone controls. It is somewhat notable for that, too. I won't debate the pros and cons of that design approach, but it was certainly a departure from Sansui's normal design practices at the time.
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Hipocrates
Super Member
You were perfectly clear, thank you, is kind of transitional product, prone to oscillation, hard to service with a weird size, with probably not enough significance for a collector, too demanding for a technician to work on them and can make some end users to suffer anxiety, sounds like my type of thing... love it!
Edit: After that description somehow it remains me a Neapolitan Mastiff, inconvenient, big, powerful, not very smart and somehow demanding dog, man I miss them.
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I do all my own restorations and maintenance so finding a tech isn’t an issue. And I like the idea of knowing exactly what I have. There are so many choices from this era, but without any original plan to do so I continue to be pulled into Sansui.
DB-7
Super Member
Is the AU-X1 a must have Sansui.
For you I would say no.
Problem is you jumped from the AU-919 right into the AU-a907 alpha.
It's really hard to go backwards from there when it comes to the sound of audio.
If you were moving from the AU-919 to AU-X1. Then yes you would notice a sound quality and overall amplifier performance enhancement.
Others will argue that a restored AU-X1 will sound the same as a 919... No it wont!
Is it better than the CA/BA combination for sound quality? Again I will say yes, it is.
The AU-X1 is always on a true Sansui collectors list.
Every person that still has one agrees they are a great amp.
It is a massive hunk of audio.
Turning the big volume ever so slightly makes music muscle out of your speakers. Even at low volume you can tell the AU-X1 is the real deal.
@Bumpalump is a big fan of the AU-X1 and has details of what to do with them when restoring for stability and performance gains.
For you I would say no.
Problem is you jumped from the AU-919 right into the AU-a907 alpha.
It's really hard to go backwards from there when it comes to the sound of audio.
If you were moving from the AU-919 to AU-X1. Then yes you would notice a sound quality and overall amplifier performance enhancement.
Others will argue that a restored AU-X1 will sound the same as a 919... No it wont!
Is it better than the CA/BA combination for sound quality? Again I will say yes, it is.
The AU-X1 is always on a true Sansui collectors list.
Every person that still has one agrees they are a great amp.
It is a massive hunk of audio.
Turning the big volume ever so slightly makes music muscle out of your speakers. Even at low volume you can tell the AU-X1 is the real deal.
@Bumpalump is a big fan of the AU-X1 and has details of what to do with them when restoring for stability and performance gains.
EMenendez
Active Member
You're one of the lucky ones,!
You have the knowledge to be able to fix your own equipment.
Unfortunately, I'm on the other side, close to 50 years old, passionate for the vintage audio but I really regret not having taken an electronics course focused on audio when I was younger, given my great interest in audio, my big problem is that my knowledge is basic and I am not qualified to be able to do a restoration, you don't know how much I would like to have that knowledge to be able to fix my audio equipment.
I agree completely with @DB-7, almost. Everything except for the AU-X1 not being for you. And I understand the logic - an AU-X1 is out of line from what has looked to be a fairly chronological Sansui Sound journey for you - then you jumped right ahead to the sonic endgame - the Alpha series! But, that is no reason for you not to dive into and find appreciation for an AU-X1 - especially considering your technical abilities and curiosity. It is a real and true statement piece for the no limits late 70's speed, power and distortion killing arms race. "I think AU-X1 is the most iconic Sansui amp and worth having just for that." - @CrSens. Sansui went right to the edge of what was possible (and even a little bit over). And with no apparent shame for their unrestrained excess. A true Golden Era pioneer. For a guy who does his own restorations and builds his own speakers, I don't see how an AU-X1 could not find it's way onto your bench and into your personal Hi-Fi encyclopedia. And selfishly, I want to see and read an AU-X1 restoration thread from you! Not likely to be easy (if any of this stuff were easy it would not be as interesting), but I suspect you are are up for the task.
No tone controls - "it is perfect the way it is"
Under the hood lives a Museum of Modern (industrial) Art candidate
Phono absurdly overbuilt for the heyday of analog bliss
Some interesting AK problem solving and praise -
@Ronito6 https://audiokarma.org/forums/index.php?threads/installing-a-new-2772-into-an-x1.836320/
@augljesi https://audiokarma.org/forums/index.php?threads/sansui-au-x1.1013912/post-16533149
And no it won't fit in a rack because it is built to be placed on pedestal!
AU-X1 dwarfing the AU-919 (picture courtesy of @Vintagear) https://audiokarma.org/forums/index.php?threads/the-mighty-au-x1.672322/
The AU-X1 is not to be missed, especially by someone like you. Keep us posted!
No tone controls - "it is perfect the way it is"
Under the hood lives a Museum of Modern (industrial) Art candidate
Phono absurdly overbuilt for the heyday of analog bliss
Some interesting AK problem solving and praise -
@Ronito6 https://audiokarma.org/forums/index.php?threads/installing-a-new-2772-into-an-x1.836320/
@augljesi https://audiokarma.org/forums/index.php?threads/sansui-au-x1.1013912/post-16533149
And no it won't fit in a rack because it is built to be placed on pedestal!
AU-X1 dwarfing the AU-919 (picture courtesy of @Vintagear) https://audiokarma.org/forums/index.php?threads/the-mighty-au-x1.672322/
The AU-X1 is not to be missed, especially by someone like you. Keep us posted!
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This is a tough one…I see the point from others around the later models being more refined etc however for me, the X1 is unique it has a wonderful phono stage which is hard to beat, Sansui really focused on this part of the amp during this time, more so than a lot of the later and earlier amps you have so this is a consideration if you listen to vinyl. I own several Sansui’s and from my experience, the X1 seems to have a bit more ‘oomf’ in the bottom end which isn’t really replicated with some of the later Sansui models. As a reference I have a 819, 717, au-607nra, ba-2000/ca-2000, 9090, x119dg, 7900 and many others…given your restoration experience I think you’d enjoy the ‘challenge’ of restoring a X1 and seeing how good you can make it…if you go down this path would love to hear your thoughts compared to the rest of your impressive collection.
When I got my X1 it was faulty - but still had an intact set of original Output Transistors. It had never been worked on, and in various areas it had faults related to aging and possibly instability (i.e. burnt resistors), and also it was liberally sprinkled with Black Flags - which, as we know are responsible for stability and can fail at any time. I was absolutely determined that my one would not destroy itself, and I read everything I could find about the amp in general and anything that would improve it's stability and longevity. I used a sacrificial set of output transistors, and got to work getting rid of those Black Flags and replacing other tired components. It gave me quite the run-around but I got it 'safe' and working and then around this time Mr Martin Kuehne chimed in on the stability conversation and gave all of AK some golden tips about how to improve it's stability. I implemented his suggestions and one or two other tricks and tips. During this time I was wonderfully assisted by Ron, @Ronito6 who produced a replacement Phono Motherboard (which was apparently the epicentre of the stability issues), and my X1 just got better and better. I eventually gave it the full measure of my restoration expertise (such as it is), and now it is as solid as a rock, and sounds wonderful. I still own it, and it will take a lot for me to part with it, it is definitely 'keeper' material.
(I think I posted a list of the things I have done to my X1 - I'll see if I can find it
).But I too have moved on and currently enjoy an AU-α907MR as my main and most used amplifier, it is very special.
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It’s been a while since checking in on this thread. I got into a slump not knowing what to target next. I think an X-1 would be a good project. Much of this is about the journey as you all know. Depending on the day, I like listening to my Alphas more than my Accuphase. So I went back to the 1960’s and have a 1000a mostly done, just working on thermal issues and the multi cans. Done properly these 1000a’s with high end tubes and restorations are stunningly musical.
Wrapped up a Yamaha B-1 and a Luxman M-6000 and both interesting in their own ways. Oh and the BA-5000. And resto-modded a Conrad Johnson dac with a class A line stage with a new modern DAC section.
New wood panels for my AU-a607MR.
The 1000a has me thinking about building an amp to match up with my HK Citation I preamp… the journey continues
Wrapped up a Yamaha B-1 and a Luxman M-6000 and both interesting in their own ways. Oh and the BA-5000. And resto-modded a Conrad Johnson dac with a class A line stage with a new modern DAC section.
New wood panels for my AU-a607MR.
The 1000a has me thinking about building an amp to match up with my HK Citation I preamp… the journey continues
I think you’ll enjoy the x1 and restoration process! Btw how did you get the 607 wood panels??
The panels are home brew.
Tienes cuatro podría venderme uno soy de Lima Perú y felicito
DB-7
Super Member
Translation:
You have four, could you sell me one? I'm from Lima, Peru, and congratulations!
AU-X1 amps are available at times on Japan Auctions. Used to be yahoo Japan Auctions.
YES on the X1, especially if you are into vinyl or want to experience amazing vinyl playback. In my experience, once properly refurbished the X1 phono stage can relegate digital through a high end DAC to second fiddle.
The image below shows the amount of real estate devoted to phono reproduction. The highlighted section on the bottom (front of amp) has 4 separate power supplies, one for each MM/MC L&R channel. The highlighted section on the right has a horizontal motherboard with relays for circuit isolation and 4 separate vertical phono boards, one for each MM/MC L&R channel. The MC boards have 24 paralleled FETs for noise reduction. The highlighted transformer and filter caps on the upper left serve the phono and pre (that can switched to passive mode). It's my understanding that the phono section runs in Class A. Sansui put a lot of effort into the phono capabilities of this unit. They were not messing around.
Of course it runs in class A. It is a low level stage, there is no use skimping on output stage current consumption with a light load. Only some opamps are biased class AB and are sometimes forced into class A by injecting current into the output. That said, the phono preamp output stage of the X1 draws a lot of current but from only +/-6 V. It is an unusual engineering decision.
Just wanted to point out that the +/-6 V is for the MC Phono amp only, which is a 'step up' amplifier, it's output goes to the MM head amp which has +/-47.5 V supplies, which includes RIAA equalisation and brings the output level of the phono subsystem up to suitable levels.
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