Buzzing amp

MikeWoodward

Hi everyone 

Hope someone can help. Got a blackstar ht-5r amp which sounds great but whenI attach my ipad to jam along it sometimes starts buzzing. It only does this when the ipad is also plugged in to the mains electric, not when the ipad works off a battery. I’ve tried various things, including different plugs, extension cables etc. The confusing thing is that it doesn’t always do it? Any help appreciated. Thanks Mike

ICBM

Stop using it with the iPad on the power supply. Switch-mode power supplies like the iPad one are notorious for causing noise, although I'm not sure why it doesn't always do it - is it when the iPad is fully charged and is not drawing current from the supply?

skunkwerx

I've had numerous issues with 'other' stuff being plugged into the mains whilst my guitars are up and running. 

There be an issue where I used to plug my ipod in to something, either speakers or my laptop, or mains power, and if I hold the ipod, and rest my other arm on my guitar strings while the guitars plugged into amp etc, the strings 'burn' me. 

I also noted the metal backing of the ipod would feel like its vibrating if I gently moved my finger along it. 

Recently I discovered this again but using a pair of powered speakers that have a metal backing plate which its vol controls are mounted on. 

If I plug these speakers in to the mains, and turn on, whilst my guitar and rig is plugged in and powered up, a buzzing occurs. Most noticeable when I touch the metal backing plate of the speakers, it gets worse. 

I also noticed any metal surface on the guitar, such as the knobs or tailpiece would exhibit the same strange vibration sensation, again only ever whilst these speakers were plugged in and on. 

For shits and giggles I tried touching the metal plate on the speakers, and my strings at the same time. The burning sensations happen. 

Its fucking annoying right? 

Leaves me having to drag my laptop out and plugging that into some other speakers over the other side of the room to enable me to play along to music whilst the speakers in question are still plugged into mains, but the laptops not. Then again I really havent investigated much, but I believe that solution didnt get me issues. 

Have you another mains plug you can try? 

Failing that I think theres a bluetooth or wireless device that plugs into an aux socket, and you can then wirelessly connect your ipad to it. I think blackstar make one actually. 

That might solve it, unless the buzzing will still travel through the mains between amp and ipad (like it seems to in my instance as thats the only possible bridge between the two devices). 

ecc83

This is almost certainly a hum/earth/ground loop problem  which occurs when two earthed devices, the Five and the iPod PSU are connected with an audio cable which completes the loop.

The electronics in the HT-5 are not in fact returned directly to chassis and this technique helps avoid loops but obviously not  in every situation. The chassis is taken directly to earth as is required by law. There are several possible fixes.

Make sure the two devices share the same double outlet or diss' strip.

Cutting the audio screen of the mini jack cable (get a cheap one from Pound Land) you can do this with a scalpel or modelling knife. DO NOT REMOVE MAINS EARTHS.

Get a transformer isolator. About £5.00 online.

BUT! Is that a genuine Apple pod PSU? There are sheds of cheap copies about and the BBC have exposed samples that catch fire! Poor internal circuitry could cause hum.

Dave.

ICBM

ecc83 said:

This is almost certainly a hum/earth/ground loop problem  which occurs when two earthed devices, the Five and the iPod PSU are connected with an audio cable which completes the loop.

It can't be that - the iPad PSU isn't earthed.

The mains plug does have a metal earth pin (and may have suppression components inside, I think - I've never opened one though), but the connection to the power supply itself is via a figure-8 plug.

hotpickups

I had this quite recently. Buzz/hum went away when I plugged my amp it another wall socket so isolated from my board etc. It was a ground loop problem?

57Deluxe

Bezzing Amps

ICBM

hotpickups said:

I had this quite recently. Buzz/hum went away when I plugged my amp it another wall socket so isolated from my board etc. It was a ground loop problem?

If it was - or if it was the opposite, that the first socket was *not* earthed - then you need to get your wiring checked. If all the sockets are correctly earthed it shouldn't make any difference which one you plug into.

hotpickups

ICBM said:

hotpickups said:

I had this quite recently. Buzz/hum went away when I plugged my amp it another wall socket so isolated from my board etc. It was a ground loop problem?

If it was - or if it was the opposite, that the first socket was *not* earthed - then you need to get your wiring checked. If all the sockets are correctly earthed it shouldn't make any difference which one you plug into.

@ICBM ;I meant I was connecting my fx board and the amp into the same plug bar. When I plugged the amp into another socket on the wall it was gone or certainly reduced 

ICBM

hotpickups said:

@ICBM ;I meant I was connecting my fx board and the amp into the same plug bar. When I plugged the amp into another socket on the wall it was gone or certainly reduced 

In that case get the plug bar checked as well.

hotpickups

ICBM said:

hotpickups said:

@ICBM ;I meant I was connecting my fx board and the amp into the same plug bar. When I plugged the amp into another socket on the wall it was gone or certainly reduced 

In that case get the plug bar checked as well.

Hmmmm well I must admit it wasn't very expensive 

MikeWoodward

Thanks everyone for the help. Might be time to get my wiring checked!