This is not true all depends on what voltage they run at had them in my preamp with great sound for years.
Short Lifetime for 6NS7 Tubes
I’ve been experiencing a high rate of 6SN7 tubes and their variants becoming microphonic and some going bad way too soon. I buy NOS tubes from only two venders with stellar reputations that are often mentioned here on the forum.
Please, no lectures on the risk of buying NOS; I’ve been buying 12AU7’s and 12AX7’s for my various preamps for years from these dealers and I can only recall sending two tubes back. Anyway, I’ve owned my current preamp for one year and have been rolling in 6SN7’s.
I’ve had 6SN7GT’s and 6SN7GTB’s go microphonic in a few months time, and I’ve had a RCA 5692 "redbase" and a RCA VT-231 go bad in less than a year. This latest tube (VT-231) drove me crazy as I tried to diagnose why my system was lacking bass and detail; surely it couldn’t be a 6 month old tube. I cleaned the connections, changed cables, but it turned out to be the tubes. I don’t know if it is one or the pair that is bad.
You know who these dealers are and the tubes I buy have the test results written on the box and are matched. They offer 30 day returns, but that doesn’t help in my situation. Has anybody else experienced 6SN7’s living a short life or have I just been unlucky?
* a typo in the title, I'm really not a dummy.
Please, no lectures on the risk of buying NOS; I’ve been buying 12AU7’s and 12AX7’s for my various preamps for years from these dealers and I can only recall sending two tubes back. Anyway, I’ve owned my current preamp for one year and have been rolling in 6SN7’s.
I’ve had 6SN7GT’s and 6SN7GTB’s go microphonic in a few months time, and I’ve had a RCA 5692 "redbase" and a RCA VT-231 go bad in less than a year. This latest tube (VT-231) drove me crazy as I tried to diagnose why my system was lacking bass and detail; surely it couldn’t be a 6 month old tube. I cleaned the connections, changed cables, but it turned out to be the tubes. I don’t know if it is one or the pair that is bad.
You know who these dealers are and the tubes I buy have the test results written on the box and are matched. They offer 30 day returns, but that doesn’t help in my situation. Has anybody else experienced 6SN7’s living a short life or have I just been unlucky?
* a typo in the title, I'm really not a dummy.
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lowrider57 ... I have a new transformer on my street to correct for power swings from old grid and now line voltage is high, but stable at 120V.Actually, 120VAC isn't high household voltage at all, at least not in the U.S., where 123VAC is considered nominal voltage in many states. |
Having a steady 120 volts is fine for almost any modern gear. There is some old vintage gear from the 1950's and 1960's that supposedly work better at 110 volts (I know people who use a variac for that), but, mdoern gear should be built to work with 120. In my area, I have seen spikes above 130, and someone not to far from me measured spikes close to 140. A friend of mine had a Tron tube amp that failed repeatedly. It was always the solid state part of the amp (bridge rectifier), and the manufacturer replaced the diodes several times before he finally decided to source beefier diodes for the repair; the manufacturer said he was unaware of how widely the voltage swings in the US and did not account for this. I read that an ultra expensive Japanese solid state amp made by Technical Brain also constantly failed in service in the US but never in Japan. It turned out that Japan has rock steady voltages and the manufacturer assumed the same for the US. It appears that builders in other parts of the world are slow to pick up on something we living in the US are aware of--the US is rapidly slipping into 3rd world status. |
- 30 posts total