Revisiting some "old" ideas from 1970's - IPS, OPS

[Kay Pirinha]

Gorgeous!
Best regards!

 

[vzaichenko]

I put Valery’s Tribute 3000 driver board on a Sansui AU-9500 plug-in driver board, changed Sansui’s original T03 output transistors to NJW1308G and NJW3281G changed the emitter resistors to .22 ohm as in Valery’s Tribute OPS but only 2 output pairs instead of 3.

The Sansui has separate transformer windings of 49v for the left and right outputs and a regulated 60V supply for the driver boards.
All the supplies still have the original 45 year old capacitors and components when I did the testing.

Measuring the voltage @ the load I calculate 99.4W per channel before clipping. Definitely worth changing out the old components.

Very good job man! Cool layout of the driver boards

 

[savvas]

... and how it sounds ?

 

[stonehome]

Thanks. I can't take credit for the layout though.

...and how it sounds? When I knew it would work I started updating components so I haven't listened yet. Soon though.;-)

 

[stocktrader200]

stonehome, nice job on your "new" AU-9500. The sound should be excellent, you also saw a power increase to 99.4w. Mine went from 45w to 72w RMS before clipping. I hiked the regulated supply to 44v rails to get there. SX-780 has 40v output rails which sag to 36v under load.

 

[stonehome]

Sansui AU-9500/Tribute 3000

Well I finished replacing all the electrolytic capacitors in the power supply and throughout the amp. I am pleased with the outcome. Well worth the effort.

Now, does anyone have an idea of the cause of the spike on the square wave.

 

[stonehome]

I should add that the square wave in the previous post is from the Sansui 9500 @ the output with an 8 ohm load with the signal into the main amp, preamp separated.

Thanks
Evan

 

[rsavas]

I can think of high frequency oscillations, unless it is from the source?

 

[thimios]

Well I finished replacing all the electrolytic capacitors in the power supply and throughout the amp. I am pleased with the outcome. Well worth the effort.

Now, does anyone have an idea of the cause of the spike on the square wave.

Scope one chanel at a time.
The output signal only.

 

[stocktrader200]

it could be:
1. Slightly more VAS compensation is required
2. More output bias could clear it up.

 

[stonehome]

Thank you for the ideas. I should have some time today to look at it again.

 

[thimios]

Zero distortion NS coming soon on YouTube! 😉
Stay tuned..

 

[thimios]

Ok, here you are. YouTube

 

[thimios]

NS OPS+VFA IPS

YouTube

 

[still4given]

That's very nice. What PSU are you using? Are you using the 21st Century controller as well? I think I have those boards. You have inspired me to finish them.

 

[thimios]

NS OPS+ VFA IPS

New video. YouTube

 

[thimios]

That's very nice. What PSU are you using? Are you using the 21st Century controller as well? I think I have those boards. You have inspired me to finish them.

Hi Terry, my power supply is a hybrid ha ha ha.
A bridge, some electrolytics, 75000uf/rail, a second cap bank(jeff's pcb, another board for cap. multiplier and +/-15v regulators..
this on the heatshink)
No, i haven't a protection other than crowbar...
Unfortunately up to now is unprotected.
I have some pcb for 21 century protection but not the microprossesor.

 

[kct]

^^^ Nice !

 

[thimios]

That's very nice. What PSU are you using? Are you using the 21st Century controller as well? I think I have those boards. You have inspired me to finish them.

Hi Terry, my power supply is a hybrid ha ha ha.
A bridge, some electrolytics, 75000uf/rail, a second cap bank(jeff's pcb, another board for cap. multiplier and +/-15v regulators..
this on the heatshink)
No, i haven't a protection other than crowbar...
Unfortunately up to now is unprotected.
I have some pcb for 21 century protection but not the microprossesor.

 

[jwilhelm]

How did you make out with your chassis?