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274B max voltage
274B max voltage
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Old 2nd June 2019, 03:00 AM   #1
sumotan is offline sumotan  Indonesia
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Default 274B max voltage

Hi Guys
A little tutorial pls. There's a Chinese made 845 mono block amp for sale at my end. It uses a 274b rectifiers per amp. Question, from data it states max input voltage with cap input is 450v ac or 500v with choke input, so how do one get away with supplying 1000v or so for the 845 using 274B rectifiers ?


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Old 2nd June 2019, 03:04 AM   #2
rayma is offline rayma  United States
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Quote:
Originally Posted by sumotan View Post
how do one get away with supplying 1000v or so for the 845 using 274B rectifiers ?
Two supplies in series?
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Old 2nd June 2019, 03:06 AM   #3
sumotan is offline sumotan  Indonesia
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Only one rectifier is used per amplifier.
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Old 2nd June 2019, 03:14 AM   #4
rayma is offline rayma  United States
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Quote:
Originally Posted by sumotan View Post
Only one rectifier is used per amplifier.
Then they don't get the 1000V. You can't use that common cathode tube as a voltage doubler.

Last edited by rayma; 2nd June 2019 at 03:17 AM.
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Old 2nd June 2019, 03:15 AM   #5
grovergardner is offline grovergardner  United States
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Quote:
Originally Posted by sumotan View Post
Only one rectifier is used per amplifier.
Either they use the 274B in a bridge with diodes, or they use it for a separate supply for the inout and driver stages.
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Old 2nd June 2019, 03:18 AM   #6
rayma is offline rayma  United States
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Originally Posted by grovergardner View Post
Either they use the 274B in a bridge with diodes, or they use it for a separate supply
for the inout and driver stages.
Right, I've seen FW bridge rectifiers done with a tube for the positive, and diodes for the negative.
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Old 2nd June 2019, 03:19 AM   #7
sumotan is offline sumotan  Indonesia
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That's the reason why I posted. This amp uses 6sn7 input & 300B driver stage. Looks very well made but can't find any info on the internet. Could the 845 voltage itself be supplied via SS bridge rectifier ?????
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Old 2nd June 2019, 03:40 AM   #8
sumotan is offline sumotan  Indonesia
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Thanks guys , negative done with diodes ??? Is there a schematics that I can refer too ?

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Old 2nd June 2019, 04:43 AM   #9
grovergardner is offline grovergardner  United States
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Quote:
Originally Posted by sumotan View Post
That's the reason why I posted. This amp uses 6sn7 input & 300B driver stage. Looks very well made but can't find any info on the internet. Could the 845 voltage itself be supplied via SS bridge rectifier ?????
Sure. They could have dual secondaries on the power transformer. You don't really want 1000vdc for the inout and driver stage anyway.
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Old 2nd June 2019, 04:53 AM   #10
sumotan is offline sumotan  Indonesia
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Agree Grovergardener just curious that it was spec this way & wonder how it would work.

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