Version 2.4 of the circuit already has R23 reduced to 22R from 33R.
Yes.... but can it be even more reduced ?
What is the purpose of this resistor ?
Yes.... but can it be even more reduced ?
What is the purpose of this resistor ?
the resistor set the collector current of the VAS...
the change increased the VAS current a little bit....
that is why distortion decreased...
limit is the VAS and big CCS collector dissipation and heat...
the resistor set the collector current of the VAS...
the change increased the VAS current a little bit....
that is why distortion decreased...
limit is the VAS and big CCS collector dissipation and heat...
So if the vas transistor is chosen to be able to cope with the power, we can remove the resistor right ?
I worry for him.That journey may have been made for his health. Not to mention the fact that he needs to clear his mind.
He's a really good guy and deserves to recover fully. Let's hope that happens.
-Chris
Nothing posted for a long.
I am still using R23 = 47R. If it is taken too low it can affect stability.
Thank you...
I see that Rod uses no resistor here: 60-80W Power Amplifier
And Bigun does neither here: TGM8 - an amplifier based on Rod Elliot P3a
That is why I wondered about this resistor..... maybe we need lower gain in this VAS ??
I worry for him.
Nothing posted for a long.
Hope everything is allright
I am still using R23 = 47R. If it is taken too low it can affect stability.
Adding in VAS degeneration reduces stage gain and thus reduces open loop gain.Thank you...
I see that Rod uses no resistor here: 60-80W Power Amplifier
And Bigun does neither here: TGM8 - an amplifier based on Rod Elliot P3a
That is why I wondered about this resistor..... maybe we need lower gain in this VAS ??
This will have a direct effect on the stability margins.
Removing the degeneration from an amplifier that has been designed to have adequate, but not excessive stability margins will perform differently and may shown signs of instability, or worse, complete oscillation.
The same argument applies to the Input LTP degeneration.
Adding in VAS degeneration reduces stage gain and thus reduces open loop gain.
This will have a direct effect on the stability margins.
Removing the degeneration from an amplifier that has been designed to have adequate, but not excessive stability margins will perform differently and may shown signs of instability, or worse, complete oscillation.
The same argument applies to the Input LTP degeneration.
Thank you Andrew.
Now I fully understand the issue.
I would also appreciate your comments about this other issue: http://www.diyaudio.com/forums/solid-state/258549-assemblage-power-amp-24.html#post5293354
Best
Ricardo
I believe the more popular opinion is to leave it out . I'm leaving it out of my build based on others experiences .
Edit: There is a discussion in this thread, or the general badger Thread. You could search the thread for LC, or lead compensation if you didn't want to sift through the 500-ish pages
Edit: There is a discussion in this thread, or the general badger Thread. You could search the thread for LC, or lead compensation if you didn't want to sift through the 500-ish pages
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I'm curious if many builders have added the lead compensation capacitor and if they consider it a "necessary" option. I've looked at the comments in the build guide but would like to know what other builders think.
Thanks
I have tried with the LC cap, using different values. It sounded best to my ears without the LC cap.
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