Sansui AU-X901 for restoration
- Thread starter Hyperion
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sansui au719
Active Member
I've finally had a chance to play the X901 at some decent volume. I expected it would be impressive, as it already sounded lovely before John did his magic to it. Now it sounds superb. Remakable. Incredible. The difference between my 719 and 919 is not that significant, especiallly since John worked to bring out the best of the 719, but IMO the X901 is now significantly better than either of them, and by some margin. It's incredibly analytical, transparent but still remains wonderfully musical. I'd have to spend some serious money to really better this amp.
John. I appreciate that you changed out a lot of the parts in the X901 and worked to bring out it's full potential. You've made it so much better than the sum of its parts. I didn't imagine it could sound this good. You have a gift for restoring Sansui amps. Thank you.
The X901 deserves centre stage
John. I appreciate that you changed out a lot of the parts in the X901 and worked to bring out it's full potential. You've made it so much better than the sum of its parts. I didn't imagine it could sound this good. You have a gift for restoring Sansui amps. Thank you.
The X901 deserves centre stage
As you probably know the AU-X701 and AU-X901 are Alpha's in all but name. They are both very fine amplifiers, and are very analytical - very revealing of sources, and source media.
I am fairly sure my AU-D11 II is better, but only 'fairly' sure, I've done a lot of upgrades to my AU-D11 II, but like so much here, it all comes down to personal preference.
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ivantoniev
New Member
Hello, all users of aidiokarma. I apologize for the bad English - I use google translator. First of all, I want to thank each of you for the shared experience, thanks to what I have read, I have repaired and recapped about 10 amplifiers and receivers and also 6 pairs of speakers. That's why I want to share my experience. One of the last amplifiers I bought and recapped was the Sansui AU-X701. I followed Hyperion's advice to recap the X901. The recapped X701 played beautifully, better than all my previous receivers. Only in terms of bass, it was inferior to the Pioneer sx1050 in strength and depth, but not in resolution I also have a Pioneer sx980, Akai AA1175.. Then I bought another X701 and compared it side by side with the recap, I have 2 pairs of Braun L710 the difference was obvious in favor of the recap. I also started to recap it without changing " C2 (x2), C3 (x2) " the difference was minimal. then I changed C2 (x2), C3 (x2) with Monacor 4.7uf . and this amplifier played noticeably better. then I changed the first c2,c3 to the first with a Mundof mcap 250 and it played better than the other. then I replaced c2,c3 on the second one with Mundorf evo. every shift until now was a step up, this time it was 2 steps, the stage expanded, the bass is incredibly bubbling, thick and strong, the highs are incredibly ethereal, crystal clear, and more resolution is felt in the entire range. maybe it's long but believe me the X701 ,X901 is worth the 50€ or so for the Mundorf EVO
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pete_mac
Super Member
Thanks for sharing!
When I recapped and upgraded my AU-X711 a few years ago, I recall replacing C2 and C3 with Panasonic polypropylene capacitors which were perfectly sized and a direct fit.
Sadly I didn't perform before and after tests after swapping these capacitors only, so I really can't say how much of the sonic improvement was attributable to the polypropylene caps. The amp was a little warm and closed-in when compared my 607MRX before the recap, and afterwards it sounded subjectively better than the 607MRX and more open in the mids and top end.
I really should set up both amps for back-to-back comparison once again! I'm acutely aware of how one's mind can play tricks, and it's been so long since I sat down and properly listened to either of these amps.
GrisPato
Super Member
Indeed, thanks for sharing.
Please be sure I don't mean anything negative with the following, and for sure do not want to discourage people to experiment to there hearts content!
Just thinking about what happens when someone makes this change with the mentioned result.
So this are the capacitors, from factory E.C. 4,7 uF bypassing the MV103s
These are used solely on the differential dual-jfet when there is a diamond differential after this.
Can I assume that they are there to create a voltage difference between the positive and negative side of the is DD circuit. And the capacitors are there to keep the voltage drop stable? Similar to the VBE multiplier bypass.
So a film capacitor should be better here. ( Although Sansui engineers always choose to use electrolytic capacitors in both positions all the way up to the alpha MRX, which just uses 1,1 uF ( back to back polar electrolytics from 2,2 uF), so easily replaced by a 1 uF film ( polyester at that time?) Which they use in the powersupply but not here?!?!)
Anyway, this should work then on all amplifiers using the Diamond Differential circuit, from AU-x19 ( AU-Dx09) forward with the same result.
Worth trying, I have some of the Panasonic 4,7 uF PP laying around, they are 15 mm lead space and will not fit in any decent way on the AU-919--> AU-D907G. I would like to see a picture of the Mundorf, with 30 * 27 mm body!
Even while I am aware of a film capacitor, especially a polypropylene, having better parameters then the electrolytic Sansui used ( but are this the important parameters for this position?) I can not really imagen such a big improvement from just replacing this capacitors. I mean, Sansui was just chasing there tails from 1978? Only thing they needed was this high quality film capacitor. Value was not available at that time in small enough package? Sansui could have used some in parallel, at least to get close to 2-5 uF. They designed the board, so could have made space for it instead of going for current mirrors and cascoded jfet pairs. Would even have been cheaper.
ivantoniev
New Member
To know . Me on my Pioneer sx-980. The differential amplifier originally had 2 pcs. 2.2uF. The replacement with Wima MKP 1 uf. there wasn't that much of a difference. On the speaker recap, Monacor, vs. Mundorf MCAP 250 there is no particular difference, I haven't tried Mundorf EVO... Surely the engineers had some reason. But...
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sorva
New Member
As you probably know the AU-X701 and AU-X901 are Alpha's in all but name. They are both very fine amplifiers, and are very analytical - very revealing of sources, and source media.
I am fairly sure my AU-D11 II is better, but only 'fairly' sure, I've done a lot of upgrades to my AU-D11 II, but like so much here, it all comes down to personal preference.
Hey there. Reviving a bit this thread as i got an AU-X901 in my posession for a few months now.
Although it looks really clean inside as i posted in show me your Sansui thread i would still like to source some parts and be prepared for a fully restoration/recapping process. @Hyperion do you happen to know if someone sells a full kit for this model as they do on ebay for several others? Or maybe since you did a great job servicing one already, would there be other parts as well to consider behind the full list mentioned when you presented the pictures for changed caps? I have no knowledge and for sure will hand it to a professional (hopefully will find someone capable here in Romania for it) when the time comes.
Tried to directly dm you but your profile appears to be "private".
Thanks in advance.
As previously mentioned I don't have a BOM for this. Also, I don't know if anyone sells a kit of parts for the AU-X901. However if I was buying a kit of parts I would only buy one from ebay seller 'Affinity for artifacts' he sells good kits and happens to be an AK member.