Excellent outcome I was going to say I had a hum issue that turned out to be a dirty tube pin glad your tube replacement got it sorted.
Hum on Tube Amp - Can't find source
I have a hum (60hz) I can hear on my speakers and it happens with my tube monoblocks (either of them). With or without interconnects, it even happens on either amp (have tried one at a time) with every circuit on the house tripped/disconnected, every other component disconnected from the wall (including the Internet/CaTV line) and no interconnects.
One amp has it as soon as it warms up whereas the other one is intermittent.
Hum X doesn't solve it, iFi Ground defender either, AVA HumDinger on powerline doesn't solve it either.
I have replaced the tubes and both amps were just tested at the factory. Replaced the circuit breaker, tightened every wire on the breaker box, checked and cleaned all connections to ground rod. Added a hum eliminator to the internet line.
Hum cycles a bit with the tube glow matching the cycles.
I'm waiting on the power company to come check the power coming to the house.
Thoughts?
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- 145 posts total
@ervikingo, so glad to hear that the hum is gone. Now it’s time to enjoy some music. |
Yes, with the significant other "quarantining" due to Covid, I moved to the music room since last Monday! Have put hours enjoying music! The (financial) downside is that i hit the vendors: - Have 2 quads of EL34's scheduled for delivery today. With those, every single tube on the amps is new - Waiting for the PS Airlens to be released so in the meantime I ordered (and received) a Wiim Pro - Ordered a budget DAC to go with it (Topping D90SE MQA) which should be delivered later in the week Currently running the Wiim to my trusty but dated spec'd Theta Gen V and alternatively to the onboard DAC on a Lexicon MC-1. Have to say, the Wiim sounds good! On A/B tests from my CD transport to the same DAC there is a discernible difference (improvement).
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@holmz The 12AX7 has more gain than a 12AT7. This can affect the amount of feedback that exists in the amplifier and can also affect something called 'phase margin'. If the amp was designed to use a lot of feedback and was a bit to close to the limits of its phase margin, by adding the slight extra gain of the 12AX7 it could have pushed the amp over the edge. So an oscillation is entirely possible, simply on account of the 12AX7. This is why it can be so important to use the tube for which the amp is designed. |
- 145 posts total