AU6900 wow!

percivilla

percivilla

Well-Known Member
I've been in the audio hobby for a while now but by strange coincidence I've never had a Sansui amplifier.

I recently came across an AU6900 with an issue. Once it warms up the music is suddenly replaced by extremely loud static. Tried it again as a pre-amp only and no issue. It's going to my tech on Monday for a full rebuild but in the meantime I've been listening to it as a pre into a recapped Nikko Alpha 450 into Energy 22 reference connoisseur's with recapped crossovers.

I've tried a number of different pre's and receivers/integrated amps in this system and the Sui beats them all! I'd been running a recapped Marantz 2240 previously. It sounded great but a bit... Polite. Clear and non-fatiguing but I always felt it wasn't as punchy or dynamic as I'd like. Slightly rolled of highs as well pushing things like cymbals into the background a bit. Dialing in more treble just made it harsh.

Well, the Sansui was the answer! I've been listening to it for a week now and it's perfect! More detailed, tighter punchier bass, and so much more dynamic. Highs are far more present while still being non fatiguing. Love this thing! Brings the groove back to the music! It's fun, satisfying and just does absolutely everything right! It also manages to make more recordings sound good than any other setup I've had.

If they all sound like this then I'd say I'm a Sansui guy now. This is absolutely the sound I've been looking for all this time!

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Heh, we have ourselves another convert. The Sansui club really needs a secret handshake or something.

In all seriousness, there seem to be a lot of long time "audio guys" who are coming around to the conclusion that Sansui is much like the old ad campaign for Colt 45 malt liquor, "It works every time". I wonder if Billy Dee Williams ever listens to a Sansui rig?
 
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I'm a recently retired collector who started rebuilding Marantz and Sherwood receiver's. Started on 2215B, S7100A, 2230, 2270 and 2252B. Learning as I go. Started on several Sansui QR-4500's and fixed a blew Output transistor and smoked transistors on the F1180 board. The cement .5 ohm resistor grounded to the output transistor leg. It smoked one F-1180 and I tried the other F1180 and smoked the other one too. Fixed both. I was going to do a recap but I think I'll wait.
I'm holding off on the Baxandall diode upgrade because it sounds so good. Been playing it for over a week and still have the cover off. The Concert mode has a nice sound on two Marantz HD660 speakers. I may be a Sansui convert soon.
I've got a 9090, G-9700 and a QRX-9001 I can't wait to play with. I liked it so good I pulled out a G-4700 to test and it sounds good too.
 
Dropped off with my tech today, told him to go nuts on it, can't wait to get it back! (He's quick). In a funny coincidence I'm in line right after he does my Uncle's Bryston 3b.

I had been on the lookout for an AU 717 when this one came along. He was going on about how amazing these sound (6900 and 7900) and how he likes them as much or better than the 717/719 and that they're a lot easier to work on!
 
If you like that AU-6900, you should hear the AU-7900. I recapped mine last year, along with removing the Sansui glue, and replacing the VD1212 diodes, the fusible resistors, and all the transistors that are known to become noisy with age. What an amplifier! I bought mine new in 1977.
And it WAS easy to work on! Because it was so easy to disassemble, I was able to use my Panavise PCB vise to hold each board vertically, as I worked on it.
About your AU-6900 noise, the power amp board, I think it’s F-2596, has a dual transistor, 2SA798. It is known to degrade over time, and become very noisy. It can be replaced with a pair of 2SA992, held face-to-face with heat shrink, with a very small dab of heat sink compound between the faces of the two transistors.
 
bubhardy said:
If you like that AU-6900, you should hear the AU-7900. I recapped mine last year, along with removing the Sansui glue, and replacing the VD1212 diodes, the fusible resistors, and all the transistors that are known to become noisy with age. What an amplifier! I bought mine new in 1977.
And it WAS easy to work on! Because it was so easy to disassemble, I was able to use my Panavise PCB vise to hold each board vertically, as I worked on it.
About your AU-6900 noise, the power amp board, I think it’s F-2596, has a dual transistor, 2SA798. It is known to degrade over time, and become very noisy. It can be replaced with a pair of 2SA992, held face-to-face with heat shrink, with a very small dab of heat sink compound between the faces of the two transistors.
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Good tips! Thanks for the info!

My tech was saying that the 6900 and 7900 share the same preamp circuit so should sound very very similar. He mentioned that these units are prone to the little diodes causing problems as well as the typical bum transistors. He's a big Sansui fan and is very familiar with their circuits so I'm very pleased it's in such good hands!
 
Well, it's back! Been listening to it for the last few days and, well, I love this thing. I've liked amps before but I love this one.

Clear, punchy, fast, dynamic, but also enough warmth mixed throughout to not give any listening fatigue. Running it flat with loudness in and it's perfect.

Huge change to the phono section, It was pretty flat and lifeless before, it's now better than through my Project Phono Box S pre.

Tech was saying quite a few caps were pretty far out of spec and a bunch of transistors were toast. The bias was four times what it should have been.

Coolest thing about the sound is how "present" the music is. Sounds like it's there in the room. Like live music.

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Yes, I know the tablet cover is blocking the vents. I'm running it as a pre-amp only, barely lukewarm.
 
NIce! I wasn't that fussy about Sansui until I found an AU-5500. I loved that little amp, and t went to a very good friend of my eldest daughter. I now have an AU-9900, which is the same styling, only more! :) Wonderful amps! I've also had an AU-D9, which has got to be the most difficult amp to match speakers to. Once I tried a pair of Genesis Physics II with them, they stayed together.
 
BilboBaggins said:
NIce! I wasn't that fussy about Sansui until I found an AU-5500. I loved that little amp, and t went to a very good friend of my eldest daughter. I now have an AU-9900, which is the same styling, only more! :) Wonderful amps! I've also had an AU-D9, which has got to be the most difficult amp to match speakers to. Once I tried a pair of Genesis Physics II with them, they stayed together.
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AU9900, sweet! Now those are beautiful!

After hearing this one, I can't figure out why Sansui weren't bigger than they were? It just sounds perfect.
 
Yeah, my AU-7900 was $400 new, in 1977, as I recall. My dad paid $500 in 1970 for his Eight-equivalent to about $3K now.
For some perspective, the new 1970 Oldsmobile Delta 88 he bought was $4800.
 
percivilla said:
Well, it's back! Been listening to it for the last few days and, well, I love this thing. I've liked amps before but I love this one.

Clear, punchy, fast, dynamic, but also enough warmth mixed throughout to not give any listening fatigue. Running it flat with loudness in and it's perfect.

Huge change to the phono section, It was pretty flat and lifeless before, it's now better than through my Project Phono Box S pre.

Tech was saying quite a few caps were pretty far out of spec and a bunch of transistors were toast. The bias was four times what it should have been.

Coolest thing about the sound is how "present" the music is. Sounds like it's there in the room. Like live music.

View attachment 2228191

Yes, I know the tablet cover is blocking the vents. I'm running it as a pre-amp only, barely lukewarm.
Click to expand...

Congratulations!

Ps That is a great album, I should put it on, haven't listened to it in a while!
 
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