Xcalibur255
Headphoneus Supremus
- Joined
- Feb 4, 2008
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I've always been a little weary of tubes with grid caps in general for precisely this reason.
Please excuse my lack of experience. I've owned various tube amps during the past dozen or so years but the past month or so with my WA 2 is my introduction to an amp using variants of the 6as7. I have just acquired a pair of NOS JAN RCA 6as7g Black Plates from a reputable dealer. There is a rather prominent hum with these tubes. Is this a common problem with these tubes?
So after a few extended sessions they should calm down? Is this a problem that is limited to RCAs?
In general, the 6AS7G family of tubes are some of the noisiest tubes out there. Then, throw them into an OTL amp as the power tube, you are prone to a lot of noise. The WA6 uses an output transformer, so it's a less noisy design to start. OTL amps tend to sound the most "tubey" and euphonic, but they are also more prone to tube noise than their transformer-coupled cousins, in my opinion.
So after a few extended sessions they should calm down? Is this a problem that is limited to RCAs?
You can find quiet RCAs, but it can take some patience. I think the TungSol/Chatham version of this tube is quite a bit better all around, but they are very hard to find these days.
If you want 6AS7s that aren't noisy try Russian 6AS7/ 6H13 they are very cheep direct from Russia and don't sound that bad..
It is a bit of a issue to find good 6AS7's RCA out there. I just put in a pair of Chatham 6AS7 tubes in my amp. I just worn out my first pair ofTungSol 6080 tubes. I agree that the TungSol/Chatham tubes are quite good.