Dilly,
I have the 6F6G's (Sylvania with Green lable, smoke glass) and bought it NOS for <$45. Before acquiring the NOS pair, I purchased a "used" pair of this type from a fellow Audiogoner here. From my recollection, the 6F6G's (I can only vouch for the Sylvania's)de-throned my GEC Kt-66 clear glass and my GEC Gold Lion KT-66 as regulator tubes on my Chenin. The GEC's are very good as a regulator for the Chenin (but people swear the best is the WE 350B? I think if you can afford it). With the the 6F6G's, I found more definition on the detail I am getting from my vinyl rig (primary music source)than the GEC's. The GEC gives me a tad bigger instrument weight but I prefer the 6F6G's sound overall. Besides, a touch of VTA can correct the "weight" I am talking about in my system but not how good the detail and other parameters would be.
My recommendation is to find a used pair of the Sylvania's that test strong not the border-line stuff. Then you should be able to compare it to what current tube you have on the regulator position at the moment. Besides $45 is not really a burden of a price tag to experiment should the tubes dissapoint you.
goodluck
I have the 6F6G's (Sylvania with Green lable, smoke glass) and bought it NOS for <$45. Before acquiring the NOS pair, I purchased a "used" pair of this type from a fellow Audiogoner here. From my recollection, the 6F6G's (I can only vouch for the Sylvania's)de-throned my GEC Kt-66 clear glass and my GEC Gold Lion KT-66 as regulator tubes on my Chenin. The GEC's are very good as a regulator for the Chenin (but people swear the best is the WE 350B? I think if you can afford it). With the the 6F6G's, I found more definition on the detail I am getting from my vinyl rig (primary music source)than the GEC's. The GEC gives me a tad bigger instrument weight but I prefer the 6F6G's sound overall. Besides, a touch of VTA can correct the "weight" I am talking about in my system but not how good the detail and other parameters would be.
My recommendation is to find a used pair of the Sylvania's that test strong not the border-line stuff. Then you should be able to compare it to what current tube you have on the regulator position at the moment. Besides $45 is not really a burden of a price tag to experiment should the tubes dissapoint you.
goodluck