Opinions on state of AU-20000 sought

[Hyperion]

Should these be re-attached? What might be the reason they were cut?

It doesn't make any sense that they were cut, as I think it disconnects the (overcurrent?), protection sensing from the emitters of TR01 & TR03, also throws their use as bias setting connection points into some doubt.

In short, we need someone like you Keith to save it!

 

[KeithD]

It doesn't make any sense that they were cut, as I think it disconnects the (overcurrent?), protection sensing from the emitters of TR01 & TR03, also throws their use as bias setting connection points into some doubt.

In short, we need someone like you Keith to save it!

Thanks for the vote of confidence, John! It is certainly worthy of a restoration, and seems a bit neglected in its current state.

I think @richardpp is right about those short red wires on F-2497 being added for measuring bias voltage (though not clear how one connected to them?) The factory wires on points 2 and 4 (orange and yellow) are connected to the driver board connector pins in F-2512, so I think the short red wires really were added by someone. The two capped wires (red & white with yellow caps) were put there by the current owner to measure bias from the top. They are just shoved into the connectors (not soldered), so easily removed.

 

[SaturationPt]

There are only so many opportunities to buy one of these, but it certainly illustrates why so many of us would prefer to buy an un-molested piece needing service to a “serviced”, “restored” and especially a “recapped” example.

 

[pete_mac]

I've always liked to look of the AU-20000 and the huge reserves of power, although they are not particularly exceptional in sonic terms from what I have read. I have never owned one or had one to repair, so I can't speak from personal experience.

Yeah, that's certainly my impression. I have a pair of them here and they are an excellent example of the sound of the period. However, to my ears, improvements in sound quality were made during subsequent generations.

Those gorgeous and imposing visuals though.... phwooooaaaaaarrr!!!! Meters!!!!!!!!

 

[richardpp]

The added complication on this unit is someone soldered wires from the solder pads on F-2512 for the F-2510 connectors directly to the driver board on the foil side. The wires are passed through the square hole between the driver board connectors on F-2512.

The wiring was done that way at the factory. Here's a photo of mine showing the same wires running through the square hole in F-2512.





...and with the driver board removed.



The original purpose of the hole in F-2512 was to locate the spring clip securing F-2510 connector board. This could better explain why the F-2510 boards were omitted at the time. The F-2510 boards were fitted again in later production units that had a new version of driver board.

Cheers

 

[KeithD]

The wiring was done that way at the factory. Here's a photo of mine showing the same wires running through the square hole in F-2512.


View attachment 3774975


...and with the driver board removed.

View attachment 3774978

The original purpose of the hole in F-2512 was to locate the spring clip securing F-2510 connector board. This could better explain why the F-2510 boards were omitted at the time. The F-2510 boards were fitted again in later production units that had a new version of driver board.

Cheers

Ah, interesting. I guess that explains why the wires are so well matched in color coding.

So, I guess the question is, are those wires really needed? Can they just be removed, or are the connectors not reliable/source of problems?

 

[richardpp]

So, I guess the question is, are those wires really needed? Can they just be removed, or are the connectors not reliable/source of problems?

I think the wires were implemented as a failsafe so it depends on the condition of your connectors. When I installed my driver boards I wired them in but later, after removing the driver boards to make some changes, I no longer felt it necessary. My connectors are in good condition and I prefer the convenience of being able to remove the boards without desoldering them.

 

[mrswakka]

I was not trying to imply there are any similarities between the AU-20000 and the BA/CA 2000, just an agreement about how good the AU-9900A sounds. From a collectors stand point I probably should have kept the BA/CA 2000 combination as they were exceptionally clean, with boxes, and probably will never find another pair for what I paid for them. We just can't keep everything. Or can we?

We can try!

 

[Plimpington2]

If the price is reasonable, it seems like an obvious buy to me. My opinion on iconic pieces like is that you don’t buy them because they exceed the performance of any other Sansui model any more than you would buy a Porsche 356 because it exceeds the performance of a 911. These items are inherently “valuable” (not even primarily in terms of money) because of what they ARE (and maybe how rare they are) rather than what they can do (which isn’t much in comparison with peers).

 

[KeithD]

If the price is reasonable, it seems like an obvious buy to me. My opinion on iconic pieces like is that you don’t buy them because they exceed the performance of any other Sansui model any more than you would buy a Porsche 356 because it exceeds the performance of a 911. These items are inherently “valuable” (not even primarily in terms of money) because of what they ARE (and maybe how rare they are) rather than what they can do (which isn’t much in comparison with peers).

That's an interesting perspective, and one I had not thought about. I have come to the conclusion that if I purchase this, it will NOT be because it sounds better than any other Sansui I own (since that's just not the case after a bunch of A/B testing). But I agree, the AU-20000 is unique by many measures, not common in the U.S., and a "once in a lifetime" find locally. It also seems relatively straight forward to work on (unlike an AU-X1). This one definitely deserves a proper restoration.

 

[w1jim]

`I have a VERY early AU20000 and it too was missing the connector boards. I think there was a bunch of odd wiring on the early units to get them functioning.
Mine may become a parts unit in the near future as it is bob-working.
Apparently, the early units had the temperature sensing bias transistors on the output heatsink and by the time they got hot it was too late. Later version had the temperature sensing on the driver transistors.
Best of luck!

 

[petesui]

If the price is reasonable, it seems like an obvious buy to me. My opinion on iconic pieces like is that you don’t buy them because they exceed the performance of any other Sansui model any more than you would buy a Porsche 356 because it exceeds the performance of a 911. These items are inherently “valuable” (not even primarily in terms of money) because of what they ARE (and maybe how rare they are) rather than what they can do (which isn’t much in comparison with peers).

Very well said.

I have come to the conclusion that if I purchase this, it will NOT be because it sounds better than any other Sansui I own (since that's just not the case after a bunch of A/B testing). But I agree, the AU-20000 is unique by many measures, not common in the U.S., and a "once in a lifetime" find locally.

Also well said. Of the same lineage, but certainly not as rare, I've said before that my AU-11000 and BA-2000 are perhaps the least compelling or interesting of my collection to listen to. Not bad by any means, just sort of neutral. Nonetheless, they are iconic to have, to look at, and to play with, and I do so regularly. They're not going anywhere.

So, it's settled then. We're all looking forward to your restoration!

 

[dlucy]

Agree, BA/CA-2000 are just an AU-11000A in separate boxes (and with meters). AU-20000 is most similar to BA/CA-3000.

Put this board comparison together a while ago for the Definition and Professional series.

View attachment 3774101

Have you considered posting this table in its own thread? I think many of us would find it useful.

 

[JimEGR]

I was offered an AU-20000 by a collector recently. A gorgeous amp and really the pinnacle of design for the period. That monster is a stunning piece of industrial art. The seller commented he didn't really care for how it sounded. I passed on the purchase - had too many other irons in the fire. I heard he had offered it for sale to someone else I know but then reneged on the offer. Maybe he decided to keep it after considering what the loss would feel like. I think once you have one of these, if you are a Sansui guy, you just can't let it go. Hoping to see some photos and a report of this one in your collection. You own and have done so much work on other same period amps, an AU-20000 seems destined to be in your hands.

 

[mrswakka]

If I could afford it, I’d buy it. Pretty simple!

 

[KeithD]

Have you considered posting this table in its own thread? I think many of us would find it useful.

Posted a new thread with the table and a few of my personal observations based on it.

 

[KeithD]

Completed the acquisition today. Any recommendation for where to get the correct "light green" lamps for the meters?

@LBPete sells replacement feet, so I'll be getting a set of those. Also need to source correct black screws for the case. I count at least 7 non-original screws, some of which are not really the correct size.

 

[petesui]

Completed the acquisition today.

Well done. Congrats!

 

[Plimpington2]

Completed the acquisition today. Any recommendation for where to get the correct "light green" lamps for the meters?

@LBPete sells replacement feet, so I'll be getting a set of those. Also need to source correct black screws for the case. I count at least 7 non-original screws, some of which are not really the correct size.

Doesn’t LBpete also sell the screws? I thought he did.

 

[KeithD]

Doesn’t LBpete also sell the screws? I thought he did.

That sounds familiar, I plan to PM him anyway.