OK , i didn't get everything you said ,for the moment I am working on another amp .
I will have to give an eye to this relay part , as the amp comes with intermitent default with DC on speaker , and the relay don't seem to protect the speaker .
at first look of the speaker output wiring , it seems there is no DC sensing back to the relay command .
I will have to give an eye to this relay part , as the amp comes with intermitent default with DC on speaker , and the relay don't seem to protect the speaker .
at first look of the speaker output wiring , it seems there is no DC sensing back to the relay command .
The relay driver detects mains Power. In effect a delay switch for the speaker and nearly instant off when power goes off.
my first post on the P128 mentions the speaker damaging output offset if a fuse blows.
http://www.diyaudio.com/forums/solid-state/72378-amp-blown-fuse-output-offset.html#post823989
my first post on the P128 mentions the speaker damaging output offset if a fuse blows.
http://www.diyaudio.com/forums/solid-state/72378-amp-blown-fuse-output-offset.html#post823989
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AndrewT wrote :
"The relay driver detects mains Power. In effect a delay switch for the speaker and nearly instant off when power goes off."
OK ,I'm asking myself the purpose of that device .
I have read your post on Vrail fuses I think I will remove these Vrail fuses ,more problems than any protection , AMHA .
I appreciate the anwers , did you try to remove that opamp and decrease the feedback to get the 6Db gain ? less components , less cause of fault
also I found a 10 pf miller cap on VAS BF 257 , I didn't see it on your sheme .
"The relay driver detects mains Power. In effect a delay switch for the speaker and nearly instant off when power goes off."
OK ,I'm asking myself the purpose of that device .
I have read your post on Vrail fuses I think I will remove these Vrail fuses ,more problems than any protection , AMHA .
I appreciate the anwers , did you try to remove that opamp and decrease the feedback to get the 6Db gain ? less components , less cause of fault
also I found a 10 pf miller cap on VAS BF 257 , I didn't see it on your sheme .
I have either a 22pF, or 8p2F, but it is C19. Not a Miller comp cap.
Do they call that an Input Inclusive Compensation cap?
This is typical of British Power Amplifiers for a couple of decades around 60's 70's 80's.
I did not try bypassing the opamp stage.
Maybe something for me to think about since gain is pretty high with that added 2times (+6dB) in front.
Do they call that an Input Inclusive Compensation cap?
This is typical of British Power Amplifiers for a couple of decades around 60's 70's 80's.
I did not try bypassing the opamp stage.
Maybe something for me to think about since gain is pretty high with that added 2times (+6dB) in front.
hello AndrewT , maybe it is a revision , but there is a 10 pf soldered side track betweeen base and collector of BF256 , the second stage (as there is no more 5532)
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