New tubes = new hum

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mastercraft1990

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New tubes = new hum
« on: 24 Jan 2019, 03:53 am »
I just picked up a pair of NOS Telefunken Smooth plate, diamond mark tubes for my Candela and had taken delivery of new speakers. I had the tubes in about a day before I set up the speakers and now I'm hearing a faint hum that stops as soon as I turn off the preamp.  I'm basically listening to Tidal on a Node 2. I also tried disconnecting the Node as well.  Can new tubes cause this and will it go away after they've had a chance to break in?

Tubeburner

Re: New tubes = new hum
« Reply #1 on: 24 Jan 2019, 05:10 am »
Try lifting the ground on the preamp. You can use a cheater plug and see if it is a ground loop noise. I doubt it is your tubes. I hope this helps :)

mastercraft1990

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Re: New tubes = new hum
« Reply #2 on: 4 Feb 2019, 12:50 am »
I actually swapped out the Candela for a NAD-C 658 BluOS Streaming DAC/Preamplifier.  I still have the Stratos Plus Stereo amp and still have the hum.  When I remove just one of the cables between the amp and preamp the hum stops.  I tried eliminating the ground on the amp and preamp and no change.

avta

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Re: New tubes = new hum
« Reply #3 on: 4 Feb 2019, 01:09 am »
You may already have this type of setup but try connecting all your electronics to one outlet using a power strip. That sometimes helps.

AlTran

Re: New tubes = new hum
« Reply #4 on: 4 Feb 2019, 04:46 am »
Easy fix, the hum comes from the interconnects from you preamp to amp. Try to use a different pair if IC.

mastercraft1990

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Re: New tubes = new hum
« Reply #5 on: 6 Feb 2019, 03:16 am »
I just put on a new set of AudioQuest Black Mambas, I'll try switching them out.  I'll be pissed if the are causing it!

Brettio

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Re: New tubes = new hum
« Reply #6 on: 8 Feb 2019, 12:09 am »
Did removing those cables stop the hum?

Brett

FullRangeMan

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Re: New tubes = new hum
« Reply #7 on: 8 Feb 2019, 12:12 am »
Maybe this interesting tube noise testing video help:
https://www.youtube.com/watch?v=13n1VCR6UXw