could the B+of 12ax7 only 15 voltage

[kldguitar]

I found some hybrid amp and tube effect pedal use 15 v to 12ax 7 B+. But someone think lower voltage of B+ will make the sound not good.Which one is right? Why fewer people use tube effect pedal, if it is easy damaged? what reason make tube effect pedal easy damaged?

[Don Moose]

This is called a 'starved plate' design, and they don't generally sound that great. Few people use tubes in FX boxes because to really get the advantages of the tube, you need a power supply near 300V - that's expensive and either large or hard to do.

[stokes]

When a tube is used in an amp or effects pedal in that manner it is generally a cheap way to be able to use the words "tube powered",in my opinion.Its not "easily damaged",a 12AX7 with only 15 plate volts will probably outlive you and me,and like Don said it wont sound so good,compared to using a tube with full power.To me,its just a marketing ploy to infer the amp or effect is "better" because of the tube.