Hum from speaker with Macbook Pro Plugged in

[RoadHousePiano]

Hi all, I had a gig this passed Friday and I was getting a pretty unpleasant hum coming from my JBL Ion 15". My setup was a NE5D in one channel of the JBL and my Macbook pro (running gig performer) plugged into another using a Radial Laptop DI. The Radial, if you're not familiar, has an 1/8 connector for the laptop and two 1/4 out's or one XLR out if you need to run in mono. I was running in mono. Anyway, when I unplugged my laptop i noticed that the hum stopped. I tried plugging it into it's own outlet and found the same issue. Any ideas how I can remedy this?

p.s. I don't normally run my rig in this fashion, but on gigs when we're doing our own sound I try and simplify things a bit.

[ElmerJFudd]

Happens sometimes, even with the RADIAL DI in the equation. Does it make any difference how loud you have the laptop and other gears' outputs set to vs. how loud you have the JBL set? You really want to make sure you are sending and adequate signal to the speaker and then don't need to raise the JBL to max to compensate.

 

Also, are you using the MacBook Pro with battery power or plugged into the wall? Does it make a difference either way?

 

What area of the audio frequency spectrum is the hum? Would you say low, mid or high? 40-80htz? 200-500htz? 1khz, higher? If it's electrical, you can try putting one of these on the laptop's adapter:

https://www.sweetwater.com/store/detail/HumX--ebtech-hum-by-ground-loop-hum-exterminator

You can also try putting it on the JBL and seeing what is most successful.

 

 

 

 

[AnotherScott]

Also, is your keyboard connected via its USB port or its 5-pin DIN MIDI jacks?

[Reezekeys]

I use the headphone out of my 2013 MBP with zero issues in the past few years, but I do remember occasional times with bad buzzing in the audio, only when the power adapter was used. Running the laptop on battery = noise goes away.

 

At those few times I got noise, I plugged an optical D/A box into my headphone output and that cured things. Unfortunately only older MacBook Pros have the combo analog/optical jack. Not sure when they nixed it.

[RoadHousePiano]

Thanks for the responses so far. I'm using a USB cable from the laptop to the SL88. I'd say the HUM is a fairly high frequency and it only happens when I have it plugged in. If the macbook is running on battery power, there's no hum.

[RoadHousePiano]

@Elmer, I may check out the eliminator you linked. Might do the trick.

[AnotherScott]

T I'm using a USB cable from the laptop to the SL88. I'd say the HUM is a fairly high frequency and it only happens when I have it plugged in. If the macbook is running on battery power, there's no hum.

Sounds like the problem decscribed at https://forums.musicplayer.com/ubbthreads.php/topics/2475535/Re_Yamaha_CP33_USB_Midi_noise

 

solved by modifying your USB cable (and I think some vendors sell USB cables pre-modified)

 

ETA: Alternatively, you could use the 5-pin DIN MIDI connectors instead, which also have the virtue of being more rugged.

[RoadHousePiano]

My last response was confusing. The hum only happens when I have my Macbook Power plugged in. I hadn't tried unplugging the USB cable to see but anytime I unplugged the laptop from the outlet, the hum stopped.

[burningbusch]

I'm curious as to why you can't just run on battery power when this comes up, problem solved. Tracking down these issues can be very frustrating, time-consuming and often never fully satisfying.

 

I frequently sample/record using an unplugged MacBook Pro in my home studio, not because of any loud hum, but because my noise floor is lowered a decibel or two simply by removing the computer and interface from the electrical grid. I could spend a bunch of money getting clean power to the house/studio, or I can simply unplug and go off the grid.

 

Seems that you could plug in during break to ensure you had plenty of power for any gig.

 

Busch.

[Bif_]

Use a ground lift on the computer power supply. Although I know this is not the right way to do, it works and only cost a buck.

[U.Honey]

 

My last response was confusing. The hum only happens when I have my Macbook Power plugged in. I hadn't tried unplugging the USB cable to see but anytime I unplugged the laptop from the outlet, the hum stopped.

 

The Radial Laptop DI has a ground lift button. Perhaps that was not on?

[RoadHousePiano]

I'm curious as to why you can't just run on battery power when this comes up, problem solved. Tracking down these issues can be very frustrating, time-consuming and often never fully satisfying.

 

I frequently sample/record using an unplugged MacBook Pro in my home studio, not because of any loud hum, but because my noise floor is lowered a decibel or two simply by removing the computer and interface from the electrical grid. I could spend a bunch of money getting clean power to the house/studio, or I can simply unplug and go off the grid.

 

Seems that you could plug in during break to ensure you had plenty of power for any gig.

 

Busch.

This particular gig, I came into with probably half a charge. But this isn't a bad idea at all.

[RoadHousePiano]

My last response was confusing. The hum only happens when I have my Macbook Power plugged in. I hadn't tried unplugging the USB cable to see but anytime I unplugged the laptop from the outlet, the hum stopped.

 

The Radial Laptop DI has a ground lift button. Perhaps that was not on?

I'll check this out.

[EscapeRocks]

Im following this thread. I have about 150 gigs now with my MBP and Mainstage. All kinds of venues. I have never had a hum issue, whether going direct from headphone output, or thru an audio i/o.

 

My current setup has my two controllers plugged into a usb hub then to my MBP.

Then depending on the gig I am either using a Focusrite 18i20 or an iConnectivity 4+.

 

My MBP is always plugged into power