nyazzip wrote:I have often thought about building a series string guitar amp.
what does "series string" mean? and what are the ramifications? i have examined a couple of antique and not-so-antique amps that i have, and the filaments appear to be in series. my initial and ignorant hunch would be: series equals quieter amp?
Many many years ago when tubes were in the rage, Radio manufacturers wanted to build radios at a lower price for consumers. The most expensive part of the radio was the power transformer. To eliminate the power transformer, tubes were designed with to be wired in series so that all the tubes filament voltage would add up to 121 volts.
The typical AA5 (All American 5) tube radio had 5 tubes, 12BE6, 12BA6, 12AV6, 35W4 and 50C5 for miniature 7 pin tubes or octal tubes using 12SA7, 12SK7, 12SQ7, 35Z5 and 50L6.
These tubes mentioned had 150ma filaments. Later, to conserve energy, tubes with 100ma filaments were used.
Now in the 30's radio manufacturers used tubes that were available at that time that didn't add up to 120 volts so they had a 3rd resistance wire in the line cord to drop the filament voltage... now a days we call that a curtain burner.
Sal