Helix LT Changing channels on external head issues...

[NevenT]

I saw on a you tube video how you can get the Helix LT to change channels on a head.

I've got the LT Ext Out 1/4 going to a Marshall JCM 2000 50 watt head, which is capable of channel switching.

As soon as I plug a guitar cable from the Helix Ext out 1/4 and go to the Marshall 1/4 that is for channel switching, I get a loud hum that won't go away.   I figured out how to make the channels switch, but I get a loud POP every time I go from the clean snapshot to the dirty snapshot.

I don't get any hum when I use the switcher that came with the amp.  I tried a standard guitar cable and a cable that came with a single button switcher pedal...same loud POP with both.   Also a really weird sound changing from Clean Snap Shot to Dirty snapshot.

Thanks for you replies.

[HonestOpinion]

On 12/6/2022 at 3:46 PM, NevenT said:

I saw on a you tube video how you can get the Helix LT to change channels on a head.

I've got the LT Ext Out 1/4 going to a Marshall JCM 2000 50 watt head, which is capable of channel switching.

As soon as I plug a guitar cable from the Helix Ext out 1/4 and go to the Marshall 1/4 that is for channel switching, I get a loud hum that won't go away.   I figured out how to make the channels switch, but I get a loud POP every time I go from the clean snapshot to the dirty snapshot.

I don't get any hum when I use the switcher that came with the amp.  I tried a standard guitar cable and a cable that came with a single button switcher pedal...same loud POP with both.   Also a really weird sound changing from Clean Snap Shot to Dirty snapshot.

Thanks for you replies.

 

First and foremost, you may want to check if your Marshall's switching input is "short to sleeve". See warning from manual below.

From the manual:

IMPORTANT! Connect EXT AMP 1/2 only to amplifiers that utilize “short-to-sleeve” footswitch inputs. Connecting to any other sort of input could cause permanent damage to both your amp and Helix! If you’re not sure if your amp has short-to-sleeve inputs, contact the manufacturer

 

According to the post on the link below, Marshall told this fellow the Marshall switching it "tip to sleeve". Don't know if that qualifies as "short to sleeve" but it sounds like it so maybe you can switch this amp with the LT. Proceed with caution and at your own risk. Would be a good idea to contact Marshall and ask first.

https://forum.fractalaudio.com/threads/relay-switching-on-a-marshall-jcm-2000-dsl-100.145623/

 

Also, assuming your amp is safe to be switched by the LT, take a look at the "Ext Amp" parameters under the 'Command Center' section of the manual. You may need to modify these. For example the setting the 'Select' parameter equal to 'Tip to Sleeve'.

 

Are you using a TS or TRS cable? That can sometimes make the difference and I know some users have even made custom TRS/TS cables to get their external amp switching working properly.  Sounds like a TS cable might work for your purposes but not sure.

 

Maybe someone else on the forum who has the JCM 2000 and gotten the switching to work will chime in. I do know that I had a similar problem with a different modeler and my old Boogie amp and ended up getting an RJM switcher to resolve the issue. The LT's Ext Amp switching is more flexible than the external amp settings available for that modeler were though.

 

[datacommando]

On 12/6/2022 at 8:46 PM, NevenT said:

I saw on a you tube video how you can get the Helix LT to change channels on a head.

Hi,

 

You didn’t provide a link to the video that you watched, but this is the official Line 6 video featuring the Helix LT. 
 

It doesn’t mention the Marshall JCM 2000 specifically, therefore if you have followed this video and you still have issues, maybe best to follow the advice given by @HonestOpinion in the post above, and contact Marshall directly for more information regarding their switching system.

 

 

Hope this helps/makes sense.

 

[Schmalle]

From what I've read the Helix switching circuit is using a transistor in open collector configuration. This means it is not isolated from the amp it tries to switch and ground loops are possible - the loud hum indicates that this is the case. So you'll need to find another method to switch channels.