Interference (noise) when using AC power with my laptop...

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Daddy?!
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Interference (noise) when using AC power with my laptop...

Post by Daddy?! » Wed Jul 30, 2008 6:13 pm

...That's the problem!

Whenever I have my laptop plugged into the wall via AC power and have my sound being routed to a mixer and amp (P.A.), I get a swishy, airy, white noise type of sound. Not a typical 60Hz AC ground loop, which I've had plenty of. If I pull the plug and run on batteries, it immediately returns to sounding like it should.

I am running the laptop plugged into a guitar effects rack unit and am using the power conditioner. Additionally, that whole rack unit has http://www.ebtechaudio.com/humxdes.html on the end of it.

I only have a 2 hour charge on my laptop batteries max and for a 90 minute set, that's cutting it too close to use battery power. Shouldn't I be able to run the laptop using AC power and not have to settle for all kinds of interference?

Any help would be appreciated.
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nebulae
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Post by nebulae » Wed Jul 30, 2008 7:13 pm

Your laptop power brick has a ground loop. I normally run hum-x on each humming unit. In your case, if that's the only hummer, then just put the hum-x on that.

The other solution is to get a 3-prong to 2-prong adapter, and that will elimitate the hum in your laptop. Most people report that this is safe to do.

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Daddy?!
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Post by Daddy?! » Thu Jul 31, 2008 5:58 pm

Nebulae,

I am using the Hum-X as the last/first thing on my rack (my power conditioner is plugged into the Hum-x...all other components plug into the same power conditioner) before going into the wall for AC power.

Is it possible to have to need another Hum-X somewhere down the line....say, plug my laptop into a Hum-X and then into the power conditioner? I always thought that one Hum-X in a line/power strip would handle ALL the loops/hum that might exist normally.

Will try the 3-2 adapter to see if that helps first.

Thanks for the advice!


Daddy?!
Last edited by Daddy?! on Thu Jul 31, 2008 6:00 pm, edited 1 time in total.
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nebulae
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Post by nebulae » Thu Jul 31, 2008 6:00 pm

that hum-x will only work for the unit that's causing ground hum...you can't put it at the end of a chain of items and have it elimate all of them.

either put the hum-x on the laptop brick, or use the 3-to-2 adapter. :)

report back with your findings.
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Daddy?!
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Post by Daddy?! » Thu Jul 31, 2008 6:02 pm

Wow! That was quick...kind of like IM'ing. Will report back with the findings. You clarified before I could even ask the ?.

Fantastic customer service, Mate!

Cheers,


Daddy?!
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nebulae
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Post by nebulae » Thu Jul 31, 2008 6:03 pm

^ who's yo daddy, mofo?

:P
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Deft
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............

Post by Deft » Thu Jul 31, 2008 6:25 pm

If your equipment has a true safety ground connection, do not use a plug adaptor to defeat it. Doing so could be extremely serious (i.e. death) if the equipment develops a fault!

nebulae
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Post by nebulae » Thu Jul 31, 2008 6:27 pm

^ agreed, which is why I'd get a seperate hum-x for each offending hummer...but that's expensive.

but you can use the adapter ($2) to find out if that'll do the trick, and then purchase the hum-x as needed.
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Noel
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Post by Noel » Thu Jul 31, 2008 7:46 pm

Alternatively you could consider feeding your audio through a transformer coupled DI box with an earth lift switch.

This is such a common problem that makers of digital audio equipment should really build in this type of isolation.
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nebulae
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Post by nebulae » Thu Jul 31, 2008 7:53 pm

^ I have issues with any solution that actually filters the audio...and you're right, manufacturers should really resolve this very common issue
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DGA
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Post by DGA » Thu Jul 31, 2008 9:00 pm

it's a common problem with laptop power supply design. considering the power supplies are sealed and the laptops themselves use dc voltage, this is a safe application to lift the earth.

cheaper di boxes can also reduce bass response due to inferior transformers.

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Post by Noel » Thu Jul 31, 2008 10:20 pm

Posted in wrong forum - sorry
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Daddy?!
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Post by Daddy?! » Fri Aug 01, 2008 1:53 pm

nebulae wrote:that hum-x will only work for the unit that's causing ground hum...you can't put it at the end of a chain of items and have it elimate all of them.

either put the hum-x on the laptop brick, or use the 3-to-2 adapter. :)

report back with your findings.
Tried the 3-2 adaptor and immediately it was a perfect fix! Chalk one up for the home team. :D

^ agreed, which is why I'd get a seperate hum-x for each offending hummer...but that's expensive. :cry:

but you can use the adapter ($2) to find out if that'll do the trick, and then purchase the hum-x as needed.

Since the 3-2 solved the problem, is it safe to continue with it, or would I do better/safer to buy another Hum-X and use it in place of the 3-2 adaptor? Also, is there a possibility that the Hum-X may NOT solve the problem like the 3-2 adaptor did? (Wouldn't that beat all? :evil: )


Thanks to all for your help....that interference was going to be very bad at a gig. 8O
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nebulae
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Post by nebulae » Fri Aug 01, 2008 1:55 pm

I think you can be fine with the 3-2 adapter...many people have reported it to be ok...

I wanted peace of mind so I bought the hum-x for the laptop adapter. It's gonna work for sure because it basically does what the 3-2 adapter does, but it does it safely.

Up to you - if you fry yourself, don't blame me. Just bequeath me your license for Live.
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Daddy?!
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Post by Daddy?! » Fri Aug 01, 2008 2:28 pm

nebulae wrote:I think you can be fine with the 3-2 adapter...many people have reported it to be ok...

I wanted peace of mind so I bought the hum-x for the laptop adapter. It's gonna work for sure because it basically does what the 3-2 adapter does, but it does it safely.

Up to you - if you fry yourself, don't blame me. Just bequeath me your license for Live.
Eloquently put! Got any use for a SONAR license, too? Thanks! I'll probably end up buying another one 'just to be safe'. Peace of mind is sometimes worth a set amount of money.....in this case, probably about $59.99. :x

While I'm at it, I just find the term 'Kraut Rock' funny. It makes me quietly chuckle to myself, even though I've really no idea what it is. I am lead to believe that it has a somewhat negative connotation associated with it. Perhaps a bit like 'hair metal' is regarded in the states.

Oy!!
He likes a whiskey drink, he likes a cider drink, he likes a vodka drink, he likes a drinky-drink.

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