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Heater capacity on 6.3 v Secondary

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Heater capacity on 6.3 v Secondary
Bassman Offline

Posts: 8
Threads: 5
Joined: Nov 2022
Location: London (England, not Ontario)
Bio: I am a bassist and electronic hobbyist who makes, modifies and repairs musical equipment.
Including valve preamps and amplifiers.
Currently on my second TUT3 project.
Country: United Kingdom
#1
03-29-2026, 06:58 AM (This post was last modified: 03-29-2026, 07:54 AM by Bassman. Edit Reason: can't spell )
Hi all.

I am part way through a build of Kevin's Custom Special amplifier from the TUT3 book.  Great circuit.

Checking my current needs for the 6.3VAC secondary, I calculate 4x 1.5 A for the 6CA7 valves and 3x .3 A for the 12AX7 valves.
Which comes to 6.9 Amperes.

The rating for the specified Hammond 278CX transformer is 6 Amperes on the 6.3 volt secondary.

15% over the rated capacity seems a lot to me.  Am I being overly conservative?
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Heater capacity on 6.3 v Secondary - by Bassman - 03-29-2026, 06:58 AM

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