Loud humming from LX2

Power Amps
1

Hi Guys,
New to the board here so hello to all first of all!

I am experiencing an issue with my setup. I run a Fractal Axe fx 3 into a Fryette LX 2 power amp. At my last show, i switch on the LX2 to allow it to warm up and i connect the XLR outputs of the Axe Fx to the Power Amp. As i went to connect the IEC connector to the back of the unit i pushed the plug piece home on the Fractal and immediately the LX2 started to emit a loud buzzing sound. The Axe fx wasnt even switched on at this point. I disconnected everything and sent my Axe fx to Fractals Service department and they could not replicate the fault stating that the Axe fx was operating normally on their test equipment and provided video evidence. This leads me here. Could it be the power amp causing the issue? If so, would anybody on here have any idea whats causing this?
I am using two Xlr jacks to connect the equipment but have swapped for standard leads and the hum still persists?
I have never had equipment make a humming noise through a Power amp when it isnt evn switched on? Very confusing?
Anyway, any help would be greatly appreciated.
Neale

2

Hello again @Neale welcome :tada:

This is a very odd!

Would you post a quick video so we can see the setup? I cannot understand what is going on well enough to provide some possibilities.

Regards,

Dan

3

Hi Dan
I have a video I took a couple days back but this website says new users cannot use attachments?
Is there another way to post a video?
I hope this helps
Thanks

4

Ahh sorry – I just bumped your user level to a regular – congrates :tada: you should be able to post now – my bad.

5

…. Still saying new users can’t post attachments?

6

Log out and try again. I just changed some more settings…

7

Ok now it says file is too big?

8

:melting_face:

I have set the size limit to the maximum possible 30MB… it should be OK for a compressed video.

Until I can fix this maybe it is better to upload the video to Vimeo or YouTube? Sorry about this! I didn’t know you would hit this issue.

Regards,

Dan

9

No worries! :wink:
Thanks Dan I was just in the process of chopping the vid into tiny bits!
:joy:

10


Two halves
Hopefully this works!
Lol

11

Nice!

I guess the only thing this can be is a ground loop.

Plug one extension socket into the wall, and plug everything into that.

I cannot see what connections you have, but you might need isolation transformer somewhere in the signal path.

Regards

Dan

12

I presumed the same…?

However, I have already tried your suggestions and no cigar. What is an isolation transformer and also could it just be a valve gone bad somewhere?

13

Can I see what is plugged into to the signal path from guitar and interconnects between units?

You use an isolation transformer usually on the signal path to break loops.

I don’t understand you full signal path so cannot really suggest anything right now.

14

It looks like the LXII is turned up all the way. If so, that is a TON of gain. I run mine at Noon for gig (100db) volume. If I am connected to a guitar and walk up close to the unit, I will get some hum as well. My AxeFx III is set up to run unity gain on output 2.

Have you tried turning it down and moving the cable end away from the unit?

Agreed that a detailed rundown of your signal chain and gain staging would be helpful.

1 Like
15

Thats interesting Venta,

Maybe you could do a test for me please?

turn the LX2 up full as I have and see if it creates the same results. At least that way I know its the power amp and nothing else.

Many Thanks.

16

Yes - loud humming when LXII cranked to 10, which is what I would expect.

1 Like
17

Thanks Ventanaman!

I think that settles it.

Really appreciate you testing that for me. If it creates the same results using your set-up which resembles mine exactly, then case closed.

18

@Ventanaman thanks for your help in figuring this out :clap:

19

Out of curiosity I picked up a Morley Hum Exterminator, and… the hum is exterminated.

1 Like
20

Hey @Ventanaman

Thanks for coming back with this information. Is that a ground loop breaking technology?

Regards

Dan