Earth loop question

Telejester

In our bedroom I have an extension lead which has my ht5r head and trex power supply for FX pedals plugged into it. I thought about buying a fender champion 20 combo for it's cleans only and a boss A/B selector. I wish to bypass the pedalboard completely for when I select the fender combo , hence the A/B.I would be plugging the fender into an unused socket on my extension lead and having it powered up at the same time as my ht5r head and FX pedal power supply..........could I run into earth loop hum issues with this ?

ICBM

Possibly, but you won't know until you try it - it depends on the amps and sometimes the location. Some amps have a 'partial ground lift' - the audio circuit ground is not directly connected to the earthed chassis. The Blackstar is one of these so in theory it should be less prone to it.

ecc83

IC beat me to it! Blackstars also have decently low FX send impedances so if needed an iso transformer can be used. You can get a twin channel iso-traff from Amazon for about a fiver but despite the very low cost they are really quite good. Deffo good enough for rock and roll!

BTW, if you can keep all the mains plugs on one strip.

Dave.

Telejester

i just watched shane diorio demoing the champion 20 and  for a home use clean amp for not a lot of money it sounds pretty nice to me. if i did buy one and the a/b and powered all from the same extension lead and got a ground loop.......the simplest and cheapest fix would be what ?

ICBM

Telejester said:

i just watched shane diorio demoing the champion 20 and  for a home use clean amp for not a lot of money it sounds pretty nice to me. if i did buy one and the a/b and powered all from the same extension lead and got a ground loop.......the simplest and cheapest fix would be what ?

Cutting the ground connection in one of the cables connecting the various pieces of kit. Which one, you may need to experiment with.

JohnPerry

Behringer Hum Destroyer is cheap and brilliant, just as good as the pricier hum eliminators (I've had a couple) 

DJH83004

ICBM said:

Telejester said:

i just watched shane diorio demoing the champion 20 and  for a home use clean amp for not a lot of money it sounds pretty nice to me. if i did buy one and the a/b and powered all from the same extension lead and got a ground loop.......the simplest and cheapest fix would be what ?

Cutting the ground connection in one of the cables connecting the various pieces of kit. Which one, you may need to experiment with.

Just for clarity, IC does NOT mean disconnecting the the earth lead from the mains plug of any of the equipment, trust that is obvious, but has to be mentioned 

ICBM

DJH83004 said:

Just for clarity, IC does NOT mean disconnecting the the earth lead from the mains plug of any of the equipment, trust that is obvious, but has to be mentioned 

Sorry! I should have specifically said that.

ecc83

https://www.amazon.co.uk/AV-Link-Ground-Loop-Isolator/dp/B000NVWB9O/ref=sr_1_5?ie=UTF8&qid=1509875719&sr=8-5&keywords=ground+loop

That ^ is the one I meant. With all these isolation transformers they are low Z OUTPUT isolators, not 10k-10k INput traffs . They will give very poor results in higher impedance circuits i.e. passive guitar.

Yes, lifting a SIGNAL earth can often fix a hum loop but it can also give rise to RF breakthrough, an RF 'keeper capacitor' in the shield path generally sorts that. ...Hum/ground loops are often a reet PITA to sort!

Dave.