VH4 hum/ground loop issue

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Tabs

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I just wanted to check here on this issue I'm having before I buy anything else in an attempt to fix it. I'm having a major hum problem trying to run my VH4 and my new Fractal Axe-FX processor/preamp together using the "four cable method."

The signal path goes like this:

Guitar > Axe-FX front input
Axe-FX Output 2 > VH4 front input
VH4 Send 1 > Axe-FX Input 2
Axe-FX Output 1 > VH4 serial return

What this is basically allowing me to do is place effects correctly, pre or post VH4 preamp, as well as use the Axe-FX's preamp into the VH4's power amp, bypassing the VH4 preamp. There's a ton of hum through all 3 of those lines when I do this. I'm using good short Mogami cable for this so I don't think it's a shielding problem or anything like that. Both the VH4 and the Axe-FX are dead silent on their own.

Both units are plugged into a Monster Pro 2500 Power Conditioner, which is plugged into a single outlet. I've observed the problem at two separate locations, both with correct wiring etc.

I'm pretty sure this is a ground loop, and people on the Axe-FX forum have told me that. I bought an Ebtech Hum Eliminator box, which can take two of the three lines - it did reduce the hum, but it's not totally gone. Do I just need to get another one to isolate all three lines? Am I doing anything bad to the signal by running everything through these boxes like that? Someone on the Axe-FX forum said that it could hurt the signal unless I used really high end isolators like the Axess Electronics BSR2.

Thanks, appreciate any help!
Ryan
 
I can recommend the Palmer Line Isolation boxes:

PLI01-p1.jpg


http://www.adamhall.com/de/index.php?cc ... try_id=191
 
I own both the Axess Electronics BS2 and the Palmer PLI-01 and they do their job very well. I used to have a stereo setup with two different amps, so I isolated one of them using the BS-2 on the input and the PLI-01 at the effects return. Worked very well.
 
Thanks guys,

Is there a US dealer for the Palmer boxes? Does anyone know if they're actually any different from the Ebtech box I already have?
 
Tabs":3spg8zbm said:
Thanks guys,

Is there a US dealer for the Palmer boxes? Does anyone know if they're actually any different from the Ebtech box I already have?
Click to expand...


For me it worked much better than the EbTech, but in one other occasion the results (PLI-1 Vs. Ebtech) were the same so can't tell for sure. The difference between the products in my case was, that the EbTech did not cut the hum completely and simultaneously made the sound a bit "dull". I believe this was caused by the audio transformer (1:1) used, which seamed to be not excellent quality and thus cutted a bit from the highest audible frequencies. I use the PLI-1 in my VH4's serial loop after the ISP Technologies Decimator, which is rather famous from its ground loop issues. The PLI-01 solves the problem completely.

Additional comment in favour of Palmer: The overal material quality and especially the durability of the products seems to be really good. I once drove a car over a Palmer DI-box and it was still functional -- a bit twisted tough. :D

You could try this for the dealer dilemma:
http://www.adamhall.com/de/AH_l--en__p--project_9
 
One more question - do I actually need 3 of these then if I return the Ebtech? With the Ebtech the hum just seems to transfer itself to whichever of the 3 lines aren't going through it - so I can kill the really bad hum coming from the Axe-FX > VH4 input (where it gets amplified by the VH4 preamp) but then I still have a less apparent amount of hum coming from the loop lines. Plugging one of the loop lines into the other channel of the Ebtech doesn't fix it, presumably because the other line isn't being isolated right?

$300 to stop hum is sort of ridiculous I think, but if I have to get 3 of these I guess I will...

I found the US dealer btw - http://www.palmergear.com

Thanks,
Ryan
 
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