Groove Tube 6CA7GE

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Author Message   Mike H Posted on Monday, July 11, 2005 - 04:55 pm:    Just spoke with Doug at Doug's Tubes. I was considering taking the plunge and buying a pair of GT-6CA7GE for my MM. Doug stated that the GT-6CA7GE could NOT stand up to the 750ish volts in a MM. In fact, I called Groove Tubes just now and they stated that the GT-6CA7GE tubes are experiencing a run away bias issue with high plate voltage. At low voltage, it's not an issue. They stated that they are running test and hope to have the issue resolve in the near future.   Paul Posted on Monday, July 11, 2005 - 05:33 pm:    Thanks for the info. I was also considering those tubes. But now I'll wait, and check up on it. Paul   Steve Kennedy (admin) Posted on Saturday, July 23, 2005 - 08:10 pm:    Thanks for the heads-up! This is the first I have heard of this problem. SInce the ORIGINAL models stood up to MM amps just fine I wonder what is different about these "reissues"? Steve   michael kaus Posted on Sunday, July 24, 2005 - 06:28 am:    Actually, the originals had a problem with the bias runaway also. That was the reason they went to the solid state driver circuit. I had one back in the 70's, bought new(I worked there) at Hamilton Music that would melt down tubes at the oddest times. Sent it back to MM to "correct" the problem. They sent it back with the SS driver in place and it was never the same amp. The SS driver sounded pretty cheezy compared to the tube PI. That's why they're having problemd with them. It just wasn't designed for that much voltage. Maybe they copied them too good! I use JJ's and bias just a TAD cooler and no problems.