Gilbert Posted March 4, 2005 Share Posted March 4, 2005 In my greedy quest to suck up tube stock, I purchased some two 12BH7A, What I need is the two 12BH7. Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted March 4, 2005 Share Posted March 4, 2005 Main difference, as I understand it, is the "A" designation denotes the ability to allow/accept fast heating - was an issue in the tube TV days where you wanted faster warm up time on TV's. The older 12BH7's seem to be without the "A" designations, but the 1950's and later are usually "A" designated (at least in the RCA's, anyway). In our case (Mc tube amp owners), either works good. Sounds like we both have been looking for the same stuff - I've been hunting/gathering black plate 12BH7's for the MC-30's. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted March 4, 2005 Share Posted March 4, 2005 The "A"s have a maximum plate voltage of 450VDC the others are max 300VDC all other specs including heater current are the same. Rick Quote Link to comment Share on other sites More sharing options...
Gilbert Posted March 4, 2005 Author Share Posted March 4, 2005 So, if I understand you guys correctly, there is no sonic difference between the 2. I though for a sec. I may have screwed the pooch, but I guess I'm okay. Just a minor heart flutter, no full blown caridac arrest. Wheew! Quote Link to comment Share on other sites More sharing options...
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