Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: audiosalvage on December 31, 2023, 09:01:00 pm

Title: Tube effects loop question
Post by: audiosalvage on December 31, 2023, 09:01:00 pm
Hey folks,  I'm building a Merlin design tube effects loop, and wondering if shielded wire is required.  Thank you
Title: Re: Tube effects loop question
Post by: d95err on December 31, 2023, 11:13:24 pm
For which wires?
Title: Re: Tube effects loop question
Post by: audiosalvage on December 31, 2023, 11:15:37 pm
in and out, send and return
Title: Re: Tube effects loop question
Post by: d95err on January 01, 2024, 05:44:53 am
It's certainly not required. Since the loop is late in the signal chain, noise usually isn't much of an issue.

If the layout has long wires (e.g. from send/return level controls on the front panel to/from jacks at the back) I would probably use shielded wire. If everything is near the back I wouldn't bother with shielding.
Title: Re: Tube effects loop question
Post by: Ronquest on January 01, 2024, 07:42:13 am
If you have some distance to go with the wires, better shield them.  That return gain stage is a (hi gain) stage.  No sense in not using shielded wire IMO.  I always do.

I've used Merlin's series loop many times, it's great with just a patch cable in the loop and using the loop's send volume to cut gain and drive the prior gain stages  and the loop's cathode follower harder before the master volume.  Some different over driven tones there worth trying out. 
Title: Re: Tube effects loop question
Post by: JPK on January 02, 2024, 08:51:42 am
Yep shield. Unless it's just an inch or two. Anything over that, I would. In my last one the send came from the board to the send jack (6-8 inches). That was shielded. Return went directly from the return jack to the tube socket via 0.1uF cap so no shield (note: forgot to shrink tube the shield drain and didn't want to re-do it, oh the OCD  :help: ).