Thanks for your response. It appears I still have a lot of reading to do

Hi guys,
First question here. I've recently revived my interest in electronics and have built a few
FX pedals. Now I've been looking at building a little practice amp. I've built the Ruby but
I've been looking for something with a little more power.

Many of the designs I've come across need bipolar power, ie. +/- 35 V for example.
I've seen the schems and noticed there's 3 power-in termials: -35, ground, and +35
This has been doing my head in, so there's a few parts to my question.

a. How is this example different from using zero Volt ground and +70V?
b. If a project says it requires an 18V bipolar power supply, does this mean -9V, 0V, +9V,
a total difference of 18V? Or -18V, 0V, +18V?
c. What are the advantages of bipolar power supplies? I've noticed that larger DC-powered amps
almost exclusively use them.

I've tried Googling answers to these questions, but I've had very little luck. Maybe I'm searching the
wrong keywords.

Thanks in advance for your help,

Cameron