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Post by peterhess on Dec 16, 2020 12:40:35 GMT -6
Hey folks, wondering if someone can help me out diagnosing this noise. Link attached to a quick mp3 in my dropbox. I *think it's noise from the tube (I won't mention what the mic is, yet... it's a good one, that many of you here are familiar with). Comes and goes in waves, and is kind of heartbreaking. It's not the pre (here it's an AML 1081), same thing is clearly present going straight to my Apollo pre. Mic cable swap, and tube cable wiggling/cleaning/re-connecting doesn't make a blip. It's about -50, which seems like that's above the acceptable noise floor. I've never troubleshot a tube mic, can I open it up and make sure the tube is seated correctly? Disconnected from power of course... anything I absolutely must know before fiddling with this? Bummed my otherwise really good day right out, I tell you what. www.dropbox.com/s/388qu149pzb76dl/tube%20mic%20noise.mp3?dl=0 |
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Post by Ward on Dec 16, 2020 13:39:38 GMT -6
move the power supply to an isolated room as far away from the rest of your gear as possible. Most 6-7 conductor cabling is minimum 25 feet, so get it a good 20' away, and plug the PSU into a good AC circuit! Make sure nothing crosses your IEC (ac line) and then run an XLR3 our of the PSU parallel with the 6-7 conductor cable back to your patch bay or preamp input.
This MIGHT work. Tube microphones are notoriously noisier than phantom powered SS/capacitor condensers.
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Post by nick8801 on Dec 16, 2020 13:41:25 GMT -6
That definitely sounds like a tube to me. My guitar amps make the same sound when the tubes start going.
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Post by Michael O. on Dec 16, 2020 15:56:19 GMT -6
I’d heard that sort of sound in a Blue Bottle once. We had two or three on hand that day, so we eliminated all the variables by switching the modular components between each particular mic (i.e., the capsules, the cables, the power supplies, and the tubes), and were unable to identify and fix the issue, so we ultimately had to send that one back to the manufacturer (never got an explanation, but my suspicion is it was a bad resistor creating the noise, or a bad cap allowing DC through to where it shouldn’t be in circuit). I’ve heard similar sounds in solid state mics, but it was always during remote tracking sessions and was always moisture/humidity related.
The only obvious question that might help to elucidate things is whether or not you let the mic warm up for long enough? It’s difficult to really diagnose without knowing anything about the particular model of mic you’re dealing with, though.
edit: just re-read and realized you didn’t try a tube swap, that would be a good place to start and might solve the sputtering issue
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Post by EmRR on Dec 16, 2020 16:18:58 GMT -6
That could be tube (or tube contact) or resistor noise. Pull the tube and put it back in a couple times to clean the contacts. See what happens. Tubes like to do this with seasonal changes.
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Post by peterhess on Dec 16, 2020 17:27:38 GMT -6
EmRR- can I safely just pull the tube, check the contacts, and put it back? And thanks- P
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Post by mike on Dec 16, 2020 19:06:25 GMT -6
can I safely just pull the tube, check the contacts, and put it back? And thanks- P
Yes, as you mentioned earlier unpowered/unplugged, gently pull the tube rocking it back and forth working its way out while pulling back works better than just trying to pull straight back IME.
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Post by EmRR on Dec 17, 2020 9:46:25 GMT -6
EmRR- can I safely just pull the tube, check the contacts, and put it back? And thanks- P Yes. You might not even need to clean the tube pins, but it can't hurt to q-tip some deoxit on there either. |
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Post by Ward on Dec 18, 2020 7:12:53 GMT -6
EmRR- can I safely just pull the tube, check the contacts, and put it back? And thanks- P Yes. You might not even need to clean the tube pins, but it can't hurt to q-tip some deoxit on there either. And in case you were wondering about tube sockets? Pipe cleaners. spray some deoxit on the end. Or another contact cleaner. |
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Post by peterhess on Dec 18, 2020 10:15:26 GMT -6
So I cleaned the pins and sockets, and still getting shifting, changing noise around -50. Cables are straight, no crosses, tried multiple outlets, swapped IECs. I think I need a tube. Thanks all for your generous help.
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Post by spindrift on Dec 18, 2020 10:31:41 GMT -6
So I cleaned the pins and sockets, and still getting shifting, changing noise around -50. Cables are straight, no crosses, tried multiple outlets, swapped IECs. I think I need a tube. Thanks all for your generous help. What kind of mic is it? |
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Post by EmRR on Dec 18, 2020 10:39:57 GMT -6
So I cleaned the pins and sockets, and still getting shifting, changing noise around -50. Cables are straight, no crosses, tried multiple outlets, swapped IECs. I think I need a tube. Thanks all for your generous help. And if a tube doesn’t do it, then it’s a resistor. Good luck! |
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