It may sound better at 12v. This circuit is really particular about the voltage on the heaters. At 9v it works just fine, but there is some good evidence that it's not optimal for tube life. Like, you'll get 2000 hours out of it rather than 6000. Powering it at 12 is theoretically better for the life of the tube, but 1000 - 2000 hours is still a good long time for a $9 tube.
Running it at 9v is sort of a convenience for those of us without a multi - tap powering system that can give 9 and 12 volts at the same time.
You wouldn't want to run this on batteries though, unless you really like buying 9volts.
Running it at 9v is sort of a convenience for those of us without a multi - tap powering system that can give 9 and 12 volts at the same time.
You wouldn't want to run this on batteries though, unless you really like buying 9volts.
