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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: purepower@nyc.rr.com

Thanks, Fred (New York).
beatlefred
ihatespamtfr066a
1 posts
 
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
eradonci
6 posts
 
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.
beatlefred OP
17 posts
 
Revisiting an old discussion :)

AU-919 might not oscillate, but the 'black flag' caps must be replaced, and in BA-F1 as well, and some other models. 

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