Helix and tube amp: strange noises

[onurb59]

Hi all, 
I have just experienced a new ( for me) way to use my helix. It's really a great piece of gear, but my old and beloved tube amps were missing me. So, I tried this chain: gtr into tube amp, speaker output of the amp into load box, load output into return of send/return1 of the helix, then a couple of blocks such as IR, reverb, etc. 
The result is amazing. 
Then, in order to be able to use some fx before amp, I tried to plug the guitar into helix first, then send the signal to tube amp input via a send/return output of helix, back to Helix via return of the same send/return, and all I get is squealing... 
Any idea about what I'm doing wrong ???

Tried with different amps and got the same problem... :(

[talwilkins]

Maybe the send/return of Helix is set to line level, which is too hot (+4 dBu)?

I think in this case you need to set it to instrument  level (-20 dBu) in global settings.

 

http://www.ovnilab.com/articles/linelevel.shtml

[onurb59]

Thanks for this suggestion, it's very interesting as it does have an influence on the problem, without solving it totally.

But it's better, no doubt!

[jbuhajla]

Try the ground lift switch on the Helix to see if that does anything for you. 

[rappel353]

I also had this issue. Here is what I did to split the tube amp into a preamp loop and a power amp loop.

NOTE: The HELIX FX SEND/RETURN numbers are for illustration only. Any will work.

 

THE PREAMP LOOP:

1. Drop the #1 HELIX FX LOOP Block.

• (set up as an INSTRUMENT I/O in Global Settings)
• Connect the HELIX #1 FX LOOP SEND to the amplifier input.
• Connect the amplifier's effects SEND to the HELIX #1 FX LOOP RETURN.

THE POWER AMP LOOP:

2. Downstream in the signal chain, drop the #2 Helix FX SEND Block. 

• (set up as an INSTRUMENT I/O in Global Settings)
• (Set DRY THRU = -120dB. This effectively sends the entire audio signal to the amplifier, reducing a chance of setting up a feedback loop.)
• Connect the HELIX #2 FX LOOP SEND to the amplifier effects return.

NOTE: I am assuming the amp is set up with the reactive load correctly installed.

3. Next in the signal chain, drop the HELIX #3 FX RETURN BLOCK.

• (set up as a LINE I/O in the Global Settings)
• (Ensure MIX = 100%. This ensures the output of the block is amplifier audio ONLY)
• (I had to set RETURN = +6.0Db to make the audio level of the output equal the audio level of the input)
• Connect the reactive load box's LINE OUT to the HELIX #3 FX RETURN.

NOTE: Be sure to add a CAB or IR to complete the signal chain.

This seems to have fixed my issue. I hope this helps you also.