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Sansui BA-2000 Modification

stonehome

stonehome

Active Member
I thought some may be interested in the Sansui BA-2000 modification project I am just finishing.

Over in the DIYaudio forum there is a thread titled "Revisiting some “old” ideas of the past." It started with a reference to an article written by engineers from Sansui. It caught my attention and I have been following along for a couple years. A few months ago the driver and OPS of the BA-3000 was updated with modern active devices, introducing a few mods mostly aimed to achieve very clean clipping behavior and low distortion.

I had just picked up a BA-2000 and decided to go for it and I’m not sorry I did. I modified the chassis and heat sink to accommodate the new boards and ended up adding a new protection system.

So I ended up with 200w per channel modern BA-3000 in a BA-2000 chassis.

I don't have all the details written yet but most of it can be see here http://stereoraven.com/amplifiers-2/sansui-2/sansui-ba-2000-rebuild-and-modification
 

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stonehome said:
I thought some may be interested in the Sansui BA-2000 modification project I am just finishing.

Over in the DIYaudio forum there is a thread titled "Revisiting some “old” ideas of the past." It started with a reference to an article written by engineers from Sansui. It caught my attention and I have been following along for a couple years. A few months ago the driver and OPS of the BA-3000 was updated with modern active devices, introducing a few mods mostly aimed to achieve very clean clipping behavior and low distortion.

I had just picked up a BA-2000 and decided to go for it and I’m not sorry I did. I modified the chassis and heat sink to accommodate the new boards and ended up adding a new protection system.

So I ended up with 200w per channel modern BA-3000 in a BA-2000 chassis.

I don't have all the details written yet but most of it can be see here http://stereoraven.com/amplifiers-2/sansui-2/sansui-ba-2000-rebuild-and-modification
Click to expand...

Looks like a tidy mod.

Any chance for some side by side “before/after” pics to better contrast the changes?

How did you measure the power increase?
 
The sound. I’ll have to answer like this. In the last five years I’ve had a single ended tube amp using a type 45 output tube. A push pull tube amp using KT88’s, another tube amp using paralleled TV sweep tubes, I had a modern designed 150w mosfet amp, an Accuphase E-303, and a restored Sansui AU-9500 and a restored BA-2000. I enjoyed listening with all these amps but I kept returning to the 9500. Now I have the modified BA-2000. This amp has all the detail of a modern amplifier but it still has that Sansui 9500 ....charm? I don’t want to say warmth because i don’t think the 9500 is warm sounding. The modified BA-2000 has the detail, separation of instruments and vocals of modern amplifiers that I like but has other qualities that remind me of the 9500. Sustain on guitar strings and cymbals are absolutely real. Vocals are again authentic and live.

Remember, this is still basically the BA-3000 circuit and it has that Sansui quality.

I have 2 pairs of speakers I listen with. One is pictured in my avatar. A diy 2-way using an Accuton tweeter and mid woofer and 2 passive woofers.

The second pair is diy 3 way with a Seas tweeter, a 6.5” phl mid range and a 15” woofer.

Of course this is with my ears in my room with my speakers but I hope this gives you an idea of sound. I haven’t used the CA-2000 yet. I have been going direct from the dac and using the level controls on the BA-2000.

I didn’t measure the power. The person who designed the boards did measurements and FFT along with another builder who did his own measurements so all has been confirmed and are posted in the DIYaudio thread.
 
Wow that is one impressive rebuild and effort., congrats! Extending the chasis is no simple task and your solution is very eliquent (I love the additions of the wood sides).
 
Thanks for the positive comments.
Lengthening the chassis 2” was pretty easy. I used” maker beams” and was able to use the exciting holes. I thought the biggist problem was going to be hiding the 2” gap. In the end I went the simplest route and added a 2” piece to the top and wood sides. The front faceplate already extended beyond the sides 3/4” so that was easy. I’m not sure if the top piece is the final solution but it’s pretty inconspicuous.
 
Nice Job Man.
So you ended up with a BA3000 inside of a BA2000. Neat. What about the power meters? what do they read?
 
Thanks JOMARK911- I haven't connected the meters yet but your right the meters will be off. So for the meters to be accurate on the original amp
the level controls would have to be at full volume is that correct?
I have been installing a protection system that uses an Atmega328 micro controller. The system monitors heatsink temperature, rail voltage, bias, offset and has soft start. If there is a problem detected the speakers are disconnected and the rails shutdown. Then the power light flashes a specified signal to indicate where the failure occurred. It's pretty straight forward to install though. It was designed by the same people that updated the BA-3000 boards.


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