Sansui AU-X1

Are there any other vintage Sansui enthusiasts out there who might own this integrated amp or knows someone who does or is just particularly familiar with the model?

I am trying to get more background information regarding the stability of its circuit design. It was THE top line model when it first came out in 1979. 160 Watts. Matching tuner was the highly regarded TU-X1. The amp is VERY sophisticated. In fact, I think too sophisticated for its own good. The problem being its tendency to blow up alot of components on the Driver Board and take out all the power output transistors as well when it suddenly goes into Oscillation. (I was told some models by Phase Linear exhibit this unpleasant tendency too- even worse).

If anyone knows if this was/is a common problem with the AU-X1 or has any other information- Please let me know either here or via email:

Thanks, Fred (New York).

Try doing some searches on the vintage gear board at Good luck. Rich
Fred, you might be better off by finding a site dedicated to vintage Sansui products. I don't know if one exists, but i would not doubt it. There is a website for just about anything you want to think about and then some. Sean
Perhaps it wasnt made clear in my post, but I already do know of other vintage Sansui sites and am corresponding with a few other people. I wanted to see if there were any new people here on this Site who might know of any information. Thanks anyway, B/F.
Greetings Fred:
I was a Sansui sales representative from the mid '70s to mid '80s and am very familiar with the AU-X1. What you said about it being "too sophisticated for its own good" is about as right-on as anything. The main problem had to do, oddly enough, with its "Super Feedforward" design, which was its main selling point. Since the SSF circuit was very stable in the AU-919, the engineers decided to try overkill in the creation of the X1. It was the unit's extremely high slew rate that caused it to oscillate at just about the drop of a hat, which always resulted in the output transistors going up in smoke. I found out the hard way that just about anything could trigger the unit into oscillation, including RF interference, connection to a speaker comparator, thin gauge or "resistive" speaker wire (this amp really NEEDED Monster Cable or Live Wire to work best; forget about "zip" cord) or even a speaker system with a less-than-flat (read that "easy") impedence curve. I also found out that one must NEVER power the unit up without speakers connected; it would blow up. Usually, leaving a headphone plugged in would prevent this from happening. When it did work, however rarely that might be, it sounded GREAT and was certainly the best transistorized integrated amp that ever came out of Japan (did A-B comparisons against the top Pioneer, Kenwood, Technics and Onkyo integrated units of the time; the only unit that came close was the AU-919 running in "bypass" mode). It was during one of these comparison tests that one of my associates decided to buy an X1. A couple of years and four sets of output transistors later, he sold the unit. He felt it was too unreliable. From the repair angle, my technician absolutely HATED the X1. According to him, each of the six demo units that we were running had blown up at least twice (this is where we discovered all the "don'ts" about this amp) and some as many as four times. He was glad that we did not sell that many units but did average an X1 every other month (for the same reason!).
I hope this helps. As repair parts are becoming increasingly difficult to find for the X1, I would recommend that you consider selling yours (assuming it still works) and, if you are still partial to the sound of Sansui amps of that era, consider getting an AU-919 (still quite a few floating around eBay). When a 919 is run in the "bypass" mode (a front panel switch), it is one of the sweetest sounding amps and closely rivals the X1, without all the trouble. It does significantly reduce the power (if memory serves, it bypassed the entire line stage and fed the power amp directly) but you will be rewarded with exceptional sound AND reliabilty.
If I may be any further assistance, please email me.
Excellent post; I've owned the Sansui integrate GU99X for almost 20 years now and it is an absolute workhorse! Originally bought it in Japan in 83'. Whenever my finicky 'high end' gear goes down this bad boor stands in to pitch hit. Frequent moves in the military subjected it to the 'torture' test and after many nicks, scratches and bent top cover she 'still' cranks out good tunes! I had her hooked up to my 4ohm'd Magnapan 1.6qr's recently while waiting for a new preamp and she drove them with " ease ". I considered selling her now and then but she now pumps her 400 watts into my HT sub.. thanks again for the post!
My AU-X1 blew up twice. Once at home and then again on the repairman's bench just after he had spent several month "overhauling" it and was in the process of testing his handy work (it was a huge bummer for him). Now neither one of us want anything to do with it. All of my other Sansui gear has been wonderful: AU-G99X, TU-X1(needs repair but works), AU-D7, and SS-20 headphones.
I too have this excellent piece of equipment and it has worked wonderfully for 20 plus years, but now I have a problem and was wondering if anyone out there knows how to remedy it. The problem: just recently purchased a low-end DVD player (Magnavox) and wanted to hook it up to the GU-99x, but there are only two input slots for the three that come on the DVD Player. The two slots on the back of the GU only have in/out. How can this work! Do I need an adapter of some sort or can I just hook up in and out and be done with it?

You will have two sets of connections: DVD player to Receiver and DVD player to TV. The DVD player will be an audio input to your Sansui and so you will connect the Sansui's AUX IN to the DVD player's Audio Out jacks. You would then need to hook up the DVD player to the TV for the picture ... how you do that will depend on the age & jacks on the back of your TV.

Regards, Rich
Fortunately I had no problems yet with my two Sansui AU-X1. The first I have owned for almost 10, the second for seven years now. And I change loudspeakers, switch on/off even without a load – no problem at all. Maybe I am a lucky guy or the European versions are more rugged. A German Sansui sales representative didn't have those problems neither. I ran both in a vertical passive bi-amping configuration which some years ago I explained also to Beatle Fred. So one loudspeaker/channel is driven by one AU-X1 alone, in terms of channel separation almost similar to a monoblock but bi-amped. Think he now uses two BA-5000 instead. But the sound of AU-X1 is absolutely outstanding and marvelous. Because this beast is as fast and strong. I will use them as long as possible together with its aligned, restored and improved mate TU-X1 and three BA-F1 in my homecinema.

Tom Frantzen, STEREO magazine, Germany
There's at least two versions of Au-X1: the early version, which was prone to oscillation, and the later production run which seems to be impoved/fixed.
To best of my knowledge, EU versions very rarely (never?) had the oscillation problem, and there seems the problem is linked to NFB loop due to very large bandwith.
AU 919 doesen't have this problem due to stabilisation circuits on the output, although the circuits are similar.