Knight amp circut voltages

autoteck1 · 18th March 2010, 04:20 AM

I just bought a transformer set from a Knight Y-762 30 watt integrated amp.(wish i had the whole amp)
I have the schematic for the original amp it seems that it would be under rated for power output as it uses 475volts on the plates and 480 volts on the screens, it is ultra linear designe using 5881's in the final stage seems to me that the voltage is very high for a "30"watt amp
The output transformer is made by North-lake #102302 code 1005727 I would love to find a mate for!!
P.S. there is 45volts on the cathode, is this the reason for the lower output,giving 430v effective on the plates ??
Trying to relearn(remember) all this stuff from when in highschool 30 years ago !!
Jim

SY · 18th March 2010, 09:05 AM

That's exactly right- the plate and screen voltage are referenced to the cathode, so you have 430V plate-to-cathode and 435V screen-to-cathode. Both of those exceed the max ratings for the 5881, but it wasn't uncommon for manufacturers to blithely abuse tubes that way.

18th March 2010, 09:05 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	That's exactly right- the plate and screen voltage are referenced to the cathode, so you have 430V plate-to-cathode and 435V screen-to-cathode. Both of those exceed the max ratings for the 5881, but it wasn't uncommon for manufacturers to blithely abuse tubes that way. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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18th March 2010, 04:20 AM	#1
autoteck1 diyAudio Member Join Date: Mar 2006 Location: utica n.y.	Knight amp circut voltages I just bought a transformer set from a Knight Y-762 30 watt integrated amp.(wish i had the whole amp) I have the schematic for the original amp it seems that it would be under rated for power output as it uses 475volts on the plates and 480 volts on the screens, it is ultra linear designe using 5881's in the final stage seems to me that the voltage is very high for a "30"watt amp The output transformer is made by North-lake #102302 code 1005727 I would love to find a mate for!! P.S. there is 45volts on the cathode, is this the reason for the lower output,giving 430v effective on the plates ?? Trying to relearn(remember) all this stuff from when in highschool 30 years ago !! Jim

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