Marshall SV20H FX Loop – Issue with digital reverb (Immerse MkII)

[Lichdraik]

Hi everyone,

I own a Marshall SV20H, and I’m facing a persistent issue when using a digital reverb pedal (Neunaber Immerse MkII) in the FX loop.
As soon as I plug the Immerse into the FX loop of the SV20H, even with the Mix set at 9 o’clock, the reverb becomes excessively present, too strong, almost as if it were overamplified.

On another amp (ENGL Savage 120 with a buffered FX loop), the Immerse works perfectly, even with higher settings.

So the problem clearly doesn’t come from the pedal or the signal chain — it seems to come from the FX Send level of the SV20H.

What I’ve already tried:

• All reverb parameters set to minimum (Mix, Depth, Pre-delay, etc.)
• Tried with and without buffer, delay placed before or after
• Tested various configurations (full FX loop vs Immerse alone)

Have other SV20H users experienced a FX Send level that’s too hot for modern digital pedals like reverb or delay?
Is there a reliable solution to attenuate only the Send level, without affecting the rest of the loop?
Has anyone successfully used a passive FX loop attenuator (like the Westminster Loop Attenuator) with this amp?

I’d be really grateful for any serious feedback or experiences, especially with this kind of pedal or this specific Marshall model.

Thanks in advance!

 

[chumbucket]

Hi everyone,

I own a Marshall SV20H, and I’m facing a persistent issue when using a digital reverb pedal (Neunaber Immerse MkII) in the FX loop.
As soon as I plug the Immerse into the FX loop of the SV20H, even with the Mix set at 9 o’clock, the reverb becomes excessively present, too strong, almost as if it were overamplified.

On another amp (ENGL Savage 120 with a buffered FX loop), the Immerse works perfectly, even with higher settings.

So the problem clearly doesn’t come from the pedal or the signal chain — it seems to come from the FX Send level of the SV20H.

What I’ve already tried:

• All reverb parameters set to minimum (Mix, Depth, Pre-delay, etc.)
• Tried with and without buffer, delay placed before or after
• Tested various configurations (full FX loop vs Immerse alone)

Have other SV20H users experienced a FX Send level that’s too hot for modern digital pedals like reverb or delay?
Is there a reliable solution to attenuate only the Send level, without affecting the rest of the loop?
Has anyone successfully used a passive FX loop attenuator (like the Westminster Loop Attenuator) with this amp?

I’d be really grateful for any serious feedback or experiences, especially with this kind of pedal or this specific Marshall model.

Thanks in advance!

This may work for you - https://www.morleyproducts.com/line-level-shifter/

 

[311boogieman]

Seems odd for sure. What @chumbucket posted may work but it sucks that you'd have to use something external like that to fix the problem. Maybe the mix pot on the amp is borked. Also, when I had the serial loop mod done to my Recto I remember him saying something about how he replaced the send or receive jack for some kind of similar reason? Also, it wasn't clear by your OP, but do other effects pedals sound overly jacked or is it just Reverb?

 

[griff10672]

I think it's more to do with the phase inverter section on a Plexi circuit ......

from what I understand ..... and have experienced with my Granger Plexi that I had .... and SV20H that I had for like a week ...

Loops don't work well in Plexi circuits ..... that's why Suhr won't put them in his ...

maybe some of the amp guys will chime in ....