Noise through PC or Amp?

Gear
1

Hey buzzers,

I’m using a Rumble 25 and decided to try out the AUX IN and PHONES for play along with PC audio.

As soon as I plug a male/male AUX the amp starts a static buzz noise which transfers to headphones when I plug them in.

It’s not entirely unplayable but unless I’m listening to something “heavy” it’s pretty annoying. Anyone have experience with mitigating this?

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2

I’m guessing it’s a ground loop from the PC to the amp. PCs have notoriously shitty built-in sound cards.

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3

A lot of times USB does it. PC with USB plugged in (especially micro-USB) can have this issue.

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4

My setup is more complicated - but I was always dealing with buzzing. Solved with two items: Behringer BDI21 which has a ground lift built in and a pack of clip on ferrite noise filters - didn’t know where buzz was coming from so I just clipped one to anything remotely suspicious :face_with_monocle: . Problem solved for under $30.

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5

Thanks will give the BDI a try. “One-day FREE delivery” we’ll see!

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6

Try plugging in the computer and the amp into the same power socket/strip. That might fix it.

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7

That would have been a nice $0 solution but didn’t work for this

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8

Just FYI, to use the ground lift, you will need a XLR to 1/4" cable. AFAIK ground lift only works through the XLR connection.

The Rumble 25 also has a contour button, which is a compressor-ish preset. That might clean up some of the noise too.

If your PC is a laptop, try to run it off the battery. Sometimes the power supplies are very noisy.

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9

Thanks for the heads up! Makes sense.

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10

Is using a mobile phone an option? Doesn’t solve your problem, but might offer an alternative.

11

Correct. It could also work over a balanced trs connection but the BDI does not have that, nor does the amp. And since it’s a Rumble 25, it also doesn’t have an XLR In. So as much as I love the BDI-21, I don’t think it will help here.

But you should keep it - it’s awesome, one of the best bargains in music.

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12

good old shotgun approach :slight_smile:

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13

Do you need an XLR jack at both ends for the ground lift to work? I run the Harley Benton Bass Expander DI and the Sansamp SH-1 into my Boehringer mixer (XLR to RCA) or Rumble 25 (XLR to 1/4") and the difference between the ground lifted and not lifted on the preamps is astounding. Placebo effect?

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14

Ahh good question. That might work.

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15

Ground Lift disconnects pin 1, the ground wire, on a three wire balanced cable connection. This breaks a ground loop.

It doesn’t have to be XLR, but it does have to be a three wire balanced cable so that it has a ground wire to disconnect.

The XLR to 1/4" is TRS (tip, ring, sleeve) on the 1/4" side. So, still a three wire balanced cable.

I wouldn’t think it’s a placebo effect at all.

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16

The weird wrinkle there is that it is very unlikely that the in on the Rumble is balanced. It’s probably a TS in, not TRS. Which means it grounds out one of the balanced signals, so what you’re actually getting that way is one side of the balanced signal pair with a floating ground. So the question now becomes how even are the grounds each component of the chain is on. This could cause other problems.

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17

Another interesting wrinkle is that I am pretty sure the ground lift on my BDI-21 was wired backwards :rofl:

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18

Afaik you don’t want to use a TRS cable for a TS input. I got a XLR to TS adapter.

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19

This is logical. Thank you. What makes me wonder is how the XLR to RCA works with the ground lift.

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Yeah. I don’t get that either.

Edit 1: Looked it up. Pin 1 (ground) is wired to Pin 3 for an RCA connection.

Edit 2: This is the same for a TS (mono) jack.

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