I have at least one of each currently-available G12 type that I've rolled through my 1x12 Randall cab to decide (Randalls sound like a Marshall cab). I picked the G12H 70th because it's the one that worked with all my amps. The 55hz worked as expected with my JTM45, but didn't sound as good with my Orange, JCM900, and others. With the 55hz, the Orange and JCM sounded filtered, a little bit of a blanket over the speaker sound. It was strange because with the JTM45 the brightness was there using the same speaker. The G12H 70th worked really well with all amps I had on hand; each amp really sounded like 'that amp'.