cobyatch
Head-Fier
Yup I agree that the 6F8G is definitely more microphonic than my other tubes, however this is much different from the common tube quirks. This is like a really loud 150Hz buzz being played at 80% volume. The first time it happened I thought something had shorted within the amp and was genuinely concerned I had damaged my headphones (and ears) lol. Only happens with the RCA 6F8G with the volume knob is turned down fully, and as soon as I turn it up a little bit the noise is radio silent and music quietly starts to come through.
Will try cleaning the pins again with some isopropyl alcohol, only gave them a quick brushdown when I first got the tube but that could definitely be the problem. FWIW, I did replace the volume pot with a stepped attenuator from eBay, but didn't think it'd be the problem since I don't experience the same thing with the other tubes.
Edit: Very interesting development, cleaning the leads didn't help remove the problem, but now noticed that it only happens with my 1/4" to XLR adapter made from the original HD800 cable. I reterminated both my HD6XX and HD800 by adding XLR males and females to the cables. I get the buzzing sound to play through both headphones using the HD800 1/4" to XLR adapter but not with the one I made from the HD6XX cable. Will double check my soldering job, but really weird that this problem only happens with this tube and adapter.
Will try cleaning the pins again with some isopropyl alcohol, only gave them a quick brushdown when I first got the tube but that could definitely be the problem. FWIW, I did replace the volume pot with a stepped attenuator from eBay, but didn't think it'd be the problem since I don't experience the same thing with the other tubes.
Edit: Very interesting development, cleaning the leads didn't help remove the problem, but now noticed that it only happens with my 1/4" to XLR adapter made from the original HD800 cable. I reterminated both my HD6XX and HD800 by adding XLR males and females to the cables. I get the buzzing sound to play through both headphones using the HD800 1/4" to XLR adapter but not with the one I made from the HD6XX cable. Will double check my soldering job, but really weird that this problem only happens with this tube and adapter.
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