Hi Guys I re-acquired a 70's SF Twin Reverb just last week, and used it on my monthly DeadHead gig last night.
It had the original Rola speakrs in it 2x12's and it had a Steel Tone-Stack mod on Channel-1, and the Reverb on Both Channels mod, but other than that the Reverb Channel is stock as far as I know.
Oh Yeah it also had the Master Volume completely bypassed (it was a pull-out type knob), and also had the Tremelo Circuit bypassed with a click-off switch on the Intensity knob.
I/we are trying to keep volume down, so I decided to run the amp in the Tilt-Back position. Which made it pretty loud where I was standing, but I think lower overall.
I had the Treble on 10 and could hear that it was pretty crispy (I coulda used a little more on guitar, but the Steel sounded really good), ...I know that JBLs of the Aluminum DustCap variety are crispier and I usually run the treble a weeeee bit below wide-open with them
I have a 4-ohm JBL E-120 here, which would be a perfect replacement/match to mainline direct from the speaker jack
I was thinking of putting that in there, and just run one speaker.
But after last nights gig, I still want to but not sure I need to!... to mod or not?
I sold this amp to another Steel player like 15 years ago, he recently passed on and I just bought it back from his wife, along with a Peavey LA 400 which a real screamer also with a Sarno Black Box in front of it (1x12 Black Widow 1203-4, 210W, 2-channel combo amp).