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Sansui AU-111G (2001) in UK

So SUPER FINE!!

:thmbsp: :banana: :music:

I'd love to have an AU-111 'Vintage' or the AU-111G.

Just Perfect.

(And Yes...I'd absolutely get it out of the rack so it can breath - vent, and stay cool, and it may a good idea to get it off the floor! Dirt and dust and all.)

Congrads on such a fine, and extremely rare, and really 'new', upgraded AU-111 Sansui tube amp. Some guys have all the luck! :)
 
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bluesky said:
So SUPER FINE!!

:thmbsp: :banana: :music:

I'd love to have an AU-111 'Vintage' or the AU-111G.

Just Perfect.

(And Yes...I'd absolutely get it out of the rack so it can breath - vent, and stay cool, and get it off the floor! Dirt and dust and all.)

Congrads on such a fine, and extremely rare, and really 'new', upgraded AU-111 Sansui tube amp. Some guys have all the luck! :)
Click to expand...

Thanks Bluesky, I remember reading Fever's post on putting him on the correct scent for these beauties, and then me.
I am very careful on the venting and dust etc.., I will do something to replace the rack. Need to earn some more brownie points with the better half first.
 
I really would love to have an AU-111 (Vintage or G). I can only imagine how wonderful they do sound not only being an AU-111 but being the later 1999/2001 TOTL Sansui 'tube' limited edition 'tube' amps! But... I probably will never have one.

I'll just be happy and content with my SS AU-X901 'Vintage'. But...if it ever crashes hard, and I hope it never does, but if it ever does... I see a AU-111 (Vintage or G) in my future!

I bet they sound just luscious. :)
 
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Baron K Rool said:
Why would you turn down the bias? That's not allowed.

Run it right, lads. Tubes like it hot.
Click to expand...

Defiantly, if they are running too cool, it will not be nice/clean to listen to.
When in factory setting at B+ almost touching 500V the Static current at 40mA the tubes were running well over 400 Deg F at idle, almost 80% of its rating.
I did some tests with a scope and THD meter to see how the signal behaved at 40mA and 30mA. There was very tiny difference between the valves set at 40mA or 30mA in THD performance at clipping start near the rated output. Also, when the Valves are set to 30mA, general temp came down to 310 Deg F. Still pretty hot.
Of course some manufactures tubes at 30mA, run colder and some hotter. I have tried RCA blackplate bottom getters, side getters, JJ harmonics, Svetlana 6L6GC and Winged C.
The RCA bottom getters at 30mA runs at 330-340 deg F and 60% of its rating, I have also been informed as these are first generation of the types and are not as robust as the later versions and this is what I use.

Absolutely, my experience in using and understanding how to use valves in HiFi is pretty limited and very recent, however my listening tests between the two at modest levels of volume I cannot tell the difference.

I also agree, we should run these as designed by the Manufacture's recommendation, then there is also a margin where we can meddle in.

Valves, biasing is a highly discussed topic and I am still learning a lot from reading the technical and perspective views on it.
 
When you bias them cooler like you're doing you are not driving them optimally. I run 6L6GC up to 65Ma with no problems - max is 72mA. Not real sure why you are worrying about temp of the valve?? I'd be more concerned with the 500v at the plate - that's at the max rated voltage there. That said, I'd be sticking to RCA 6L6GC at that voltage. New stock tubes I wouldn't even try them not worth the risk IMHO. Lowering the bias just lowers the power out, you need to review the tube data sheet to be sure you are in a suitable place there - bias @ 30mA seems kinda low but it might be suitable - I would check.

6L6GC with 500v at the plate for ~40W/ch you should be at 40mA as specified. If I wanted to run them cooler I'd probably drop the bias down to say 35mA, but I would be doing some math there before arbitrarily lowering the bias.

BTW - that's a mighty fine amp there, a real beauty!!

Cheers,
Bob
 
Bob,
Thanks, it does look unique and ageless.

Sound advise and does make sense and will digest and consider.
The B+ on these Sansui's are +493 on the Anode according to the schematic. Reality with the power fluctuations of 1% this does go over 500V. Hence the maths to run it at 60% and trying to keep the temperature around 340deg F.
Gregg of Hitestguitars was extremely helpful and reviewed the Sansui schematic and suggested the approach of biasing towards 30mA and not more than 35mA to ensure the valve operated in area of safe margin whilst ensuring no loss of HiFi. I could appreciate this as the plate voltage hovering around 500V.
I took his advise and checked with test instruments at 40 and 30 and could not notice any deterioration and then listening tests also confirmed it sounded good.
Absolutely, I am still learning and that can only be good. (Bob and Baron K rool)
We have another AU-111G owner, Johnny_Fever, he is also testing the bias at 30mA and will report on his findings. Of course, the make of 6L6GC and how robust they are will also influence the approach on this topic.
 
I could not hear any difference after lowering the bias. The main transformer seems to run cooler. I can check actual temp later today. Fever
 
johnny_fever said:
I could not hear any difference after lowering the bias. The main transformer seems to run cooler. I can check actual temp later today. Fever
Click to expand...

Thats was my perception on the hearing tests as well, look forward to see the temp results. I am going to run with it for a while before changing anything.
 
So far after 2 hrs of low volume listening (Family was home) I can say the transformer runs at 109 deg. I will crank It up when no one Is around. Fever
 
just got done playing It louder for 4 hrs and so far It only reached 113deg at the main OPT. Temp went up to 113 at idel and dropped while playing. otherwise It was 110 deg. I pushed It up a little with loudness on and went back to 113. Later Fever
 
Interesting, thats what I noticed as well, when driven the tubes start to get a bit cooler. So, a leap in assumption is even at 50% dissipation, its still hot enough and well within the linear part of the valve characteristics. Noticed this at 50%, 60% and 70%.
I will check on the scope next weekend, as to when the cross-over distortion starts to creep in and at what bias level.
 
Since I bought this amp I have been running Svetlana 6L6GC Winged C tubes. They all are running a bright blue now so I'm going to Install a quad of Sylvania 6l6gc's for grins. I will report back. Fever
 
Fever,
Winged C are suppose to be good. Seen a few positive write-ups. As per your suggestion, I have posted cold/warm/hot bias query on the Tube Audio forum, thanks for that, as there are lot more Valve experience.
Mano
 
I had one Wing C start to pop real loud. It tested fine but was bogus. I replaced It and I was back In bizz.
 
johnny_fever said:
I had one Wing C start to pop real loud. It tested fine but was bogus. I replaced It and I was back In bizz.
Click to expand...

Hope you caught it, before it did some damage. It seems the Sansui AU-111 internal design may have been copied from an idea McIntosh used in the output stage to overcome cross over distortion, with a wide mark on the bias settings. Unity Coupled is the term.
 
Just because you can't 'hear' a difference, doesn't mean it's not there.

Where are the oscilloscope tests????? I agree, playing around with the BIAS, especially if you don't understand it, is detrimental to the performance of these amps.

The Sansui engineers knew exactly what they were doing when they built this. When I start the restoration of my original AU-111 - everything will be bought back to original specs with today's new components.

On a side note, this is a beautiful amp! the Black and Gold is abit different to what I'm used to, but hey, each to their own!

-D
 
_mano said:
Hope you caught it, before it did some damage. It seems the Sansui AU-111 internal design may have been copied from an idea McIntosh used in the output stage to overcome cross over distortion, with a wide mark on the bias settings. Unity Coupled is the term.
Click to expand...

the output stage in the sansui AU111 is very special due to the make up of the output tranny every thing else is standard cook book valve
 
nadstar said:
Just because you can't 'hear' a difference, doesn't mean it's not there.

Where are the oscilloscope tests????? I agree, playing around with the BIAS, especially if you don't understand it, is detrimental to the performance of these amps.

The Sansui engineers knew exactly what they were doing when they built this. When I start the restoration of my original AU-111 - everything will be bought back to original specs with today's new components.

On a side note, this is a beautiful amp! the Black and Gold is abit different to what I'm used to, but hey, each to their own!

-D
Click to expand...
so true using test gear is the only way lol
 
I increased my bias back up near recommended setting. To 180mv & 260mv. Spec calls for 280 & 200mv since no one reported any findings with a scope. I thought maybe dropping It a little might be okay. My musician friends have mixed feelings about bias. some pamper & some cook bias. Fever
 
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