I believe both the beta bass and the concert bass are 100 watt solid state amps. I have no idea why the beta bass is so loud and the concert bass is so quiet.
Oh how I learned this since I picked up a Beta Bass.
Reading back on this thread I really used to rep the Concert Bass.
Anyway, I did and still do love the amp and between 2 of them it had been my main bass amp for years. But keep in mind, it reads 300 watts or something while the Beta series reads 100.
I did also own a Beta Lead though so one day I tried it, instant gratification. It was very Melvins-ish, like when the had the guy from Cows in the band. I knew I had to search for a Beta Bass.
It surpassed my expectations. Blows the Concerts and the Beta Lead away.