Tuesday, November 1, 2011

Sansui AU-G90X

Front, angled view

The AU-G90X amplifier is an old favourite. The matching tuner is the TU-D99X. The G90X is a X-Balanced integrated amplifier. Other X-Balanced units I have are the B-2101 and B-2102.

Sounds as good as ever, even after about 2 years in storage. Previously I had great difficulty convincing myself to put the unit back into storage. Took several months before I got around to it!

Bottom view, in storage box


I had recapped the unit a few years ago as it took more than an hour before sounding right. When examined, all the EC(s) in the PSU board showed leaks. Other EC(s) in the pre and power amplifier section showed signs of usage over many years. Panasonic ECA/FC/FM, Rubycon, Vishay BC, OSCON, silver mica(s) and Wima(s) were used during the recapping. No replacement was performed on the tone control board, since these were hardly utilised.

The original plastic foam used for cushioning the buttons were so old they disintegrate upon touch! Hence I replaced them with similar sized equivalents. The resultant produces a nice cushioned feeling when depressing the buttons.

Top view, without cover

Close-up of power amp section

Close-up of  phono section, after internal separator removed

Apologies as I forgot to take a pix of the rear in my haste to get the beastie operational.

The current pix(s) does not show the pre-amp board as these are only visible once the face plate has been removed. The PSU board can be seen from the top but is mostly obscured by the mounting before the faceplate.

Will update the missing portions another day.

Found the following while searching the internet for reviews on the "not so common" G90X.

A Swedish Magazine begun 1983 to use "Anagraph" for displaying an amps behavior. When they 1986 checked AU-G11X and AU-G90X the comment was that (Translation) they never before got an anagraph so perfect as they got with AU-G90X. The only hint can be seen at 50kHz and 100W but this hint is the smallest we have seen. Output power at clipping is stated to be 150W at 8 ohms but we measured 170W across whole frequency range

Anagraph for the AU-G90X

Uploaded the following brochure of the G90X as the information is scarce on the internet.


  1. Hi,

    I own one of these and I just brought it back from a long sleep in my basement. Having played music through an Onkyo 5.1 Home Cinema system and mainly Spotify as a source, the difference was breathtaking, going back to my old stereo. My AU-G90X is now hooked up with a Pionneer PD-S707 CD-player and plays through a pair of JBL Studio Monitor 4408.

    Music has come alive again in my house!

    Great blog!


    1. These were build to a quality, not cost. Sadly lacking in today's world unless you pay a large sum for it

    2. Yes the G90X does grow on you and reproduces audio at a quality which can only be match by the newer high end units

  2. Hi Impressive what can be found on the net.
    I am reparing an old AU G90X. The L/R channel adjustment craks when used and the sound in the rigth channel changes when the knob is being moved.
    I have taken the board out and have cleaned the pot, but I worry that this will not work for long.
    Could you help in finding a new pot for this. It is soldered to the board so it has to be a equal pot.
    I can send you a picture.

    Ricky Carstens

    1. Sansui used very high quality components. I had the same issue when I acquired it few years ago. Still working today. Once you keep using it, the issue simply goes away. Was the same with the volume knob of my Audiolab as well.

    2. If your G90X takes a while to sound right and say after more than 30min or so, the volume increases without any intervention - you will need to recap the the few 470uF on the PSU board supplying the large filter caps.

    3. Headroom gains cames from recapping the other misc EC caps. I replaced many non-EC caps on the pre-amp board and some on the power amp board.

      Please note there are bi-polar caps on the pre amp board.