Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: SoundCity85 on September 02, 2020, 02:06:52 am

Title: Marshall 2204 FX loop
Post by: SoundCity85 on September 02, 2020, 02:06:52 am

Hello,

I had great success with adding an FX loop to a DR103 preamp. Now I'm considering the same for a Marshall 2204 build. The only difference is that there is no free triode available, so I will wire in a new socket and two triodes become available for the loop. Looking again for the same concept, a level control pot on the outside, and a bypass switch. Can anyone suggest me a schematic? For the DR103 it was placed in between the treble pot and MV pot (https://el34world.com/Forum/index.php?topic=26300.0).

Best regards

Dominic

Title: Re: Marshall 2204 FX loop
Post by: Latole on September 02, 2020, 03:47:26 am

I'll use same circuit as the DR103

I'll put phase loop between Treble pot wiper side to the the side or Master Volume pot.

Title: Re: Marshall 2204 FX loop
Post by: pdf64 on September 02, 2020, 11:45:45 am

Quote from: SoundCity85 on September 02, 2020, 02:06:52 am

...a level control pot on the outside, and a bypass switch. Can anyone suggest me a schematic?...

Are you bothered about the loop flipping the signal polarity? I assume not, as the arrangement apparently used on your DR103 would have done that.
As you've now got 2 active devices, you've got more options, eg see the Merlin loops on that thread.

Title: Re: Marshall 2204 FX loop
Post by: 2deaf on September 02, 2020, 10:08:45 pm

Here's one.