cumbb , the bootstrap creates a virtual CCS powered by the output. Without this the VAS will go to the active
VAS rail. IT WON'T WORK ! If you replaced the bootstrap with a proper LED or 2Q CCS - great.
PS - if you want to learn - listen...
Maybe not smoke - but a cooked woofer ?
OS
VAS rail. IT WON'T WORK ! If you replaced the bootstrap with a proper LED or 2Q CCS - great.
PS - if you want to learn - listen...
Maybe not smoke - but a cooked woofer ?
OS
The protection DC circuit would trip immediately .
PS - I seems you do not know how basic feedback AB amps work. It would be good to learn these things
before you advise or comment possibly causing harm ??
OS
To gain audio experience, it would make more sense to replace the bias-bridging capacitor with a high capacitance first. And always listen carefully.
And then remove the bootstrap cap (not re-place with wire). Re-move. And always listen carefully after each step;-)
Would @atlvalet tell us what he hears, and also if it smokes;-)
And then remove the bootstrap cap (not re-place with wire). Re-move. And always listen carefully after each step;-)
Would @atlvalet tell us what he hears, and also if it smokes;-)
I am not volunteering my newly recapped SU-7700 for this...plus, you don't want me anywhere near a soldering iron lol
But yeah, it's easy to see if the aforementioned mods will do bad things or not. SU-7700's are relatively cheap to acquire....$200 to $300.
So someone should be able to make this happen and report back 🙂
But yeah, it's easy to see if the aforementioned mods will do bad things or not. SU-7700's are relatively cheap to acquire....$200 to $300.
So someone should be able to make this happen and report back 🙂
I won't argue stupid stupid stuff , but a bootstrapped VAS WILL run without the cap.
But it won't run right. VAS current stays at @ 5mA +/- .1mA WITH the cap.
Remove the cap, VAS fluctuates between 3 and 7mA. Distortion rises as output stage is no longer
properly biased.
That might cause thermal runaway or many other problems. So , it could end up smoke in a short time.
Would not want to run good speakers with such a crippled amp.
If Cumbb does not want a cap , why not just replace with a solid 5mA current source. ?
Believe me , if the OEM could get away without the cap - they would do it to save a $$. cheap !!!
OS
But it won't run right. VAS current stays at @ 5mA +/- .1mA WITH the cap.
Remove the cap, VAS fluctuates between 3 and 7mA. Distortion rises as output stage is no longer
properly biased.
That might cause thermal runaway or many other problems. So , it could end up smoke in a short time.
Would not want to run good speakers with such a crippled amp.
If Cumbb does not want a cap , why not just replace with a solid 5mA current source. ?
Believe me , if the OEM could get away without the cap - they would do it to save a $$. cheap !!!
OS
