• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Little Mark IV Ninja - Send/Return Loop Problems

R

rickdiculous

Aug 3, 2025
8
4
Disclosures
Moose Toneworks
#1
I have a MarkBass 102P Traveler combo and I am super confused about the send/return loop. I know MarkBass has their loops wired in parallel and there is a jumper inside the housing that can switch it to series, at least in theory.

My first problems are as follows:
1. No matter what position I place the jumper (series, parallel, or just remove entirely), the amp's behavior remains completely unchanged. What gives?
2. The volume of effects placed in the loop is very week unless I boost them to death and then the bypass is way too loud.

I don't have to use the loop but I'd like to if I can figure these problems out. Any direction would be much appreciated, especially if I'm being stupid and you can tell me how I'm being stupid.
 
#2
There may be more than one jumper on some models. There may also be another problem, or someone hit in there and modified it (causing new issues).
 
#3
For anyone else looking for an answer to this, that series/parallel jumper only affects the signal when nothing is plugged into the loop. It connects the send tip to the return tip, effectively beefing up the signal a little bit when the loop is not in use. It has nothing to do with the function of the loop in use, which I find dumb. MarkBass does a persistent parallel dry path with the loop no matter what you do.

Unless you want to do some surgery and risk a $900 doorstop, which I am certainly not above. If I ever make that alteration, I'll report back.
 
  • Like
Reactions: agedhorse and Nebadon2000
#4
rickdiculous said:
For anyone else looking for an answer to this, that series/parallel jumper only affects the signal when nothing is plugged into the loop. It connects the send tip to the return tip, effectively beefing up the signal a little bit when the loop is not in use. It has nothing to do with the function of the loop in use, which I find dumb. MarkBass does a persistent parallel dry path with the loop no matter what you do.

Unless you want to do some surgery and risk a $900 doorstop, which I am certainly not above. If I ever make that alteration, I'll report back.
Click to expand...
That's why there were some models with additional jumpers.
 
#6
I figured it out, there is a permanent parallel dry path in the S/R loop no matter what. Unless I'm prepared to find where it originates and sever the connection, it's just going to be there. Pretty much all MB amps work this what from what I can tell.
 
#7
rickdiculous said:
I figured it out, there is a permanent parallel dry path in the S/R loop no matter what. Unless I'm prepared to find where it originates and sever the connection, it's just going to be there. Pretty much all MB amps work this what from what I can tell.
Click to expand...
Which is why I mentioned this in post #4. On a few models, there was a jumper for this, most there wasn't. Tracing the circuit out is pretty tough on those amps, the opportunity to end up with a mess is a real possibility.
 
#8
agedhorse said:
Which is why I mentioned this in post #4. On a few models, there was a jumper for this, most there wasn't. Tracing the circuit out is pretty tough on those amps, the opportunity to end up with a mess is a real possibility.
Click to expand...
That's what I'm saying. The jumper, which is present in both of my MarkBass heads, only affects the behavior of the loop when not in use. It essentially connects the tips of the send/return jacks when empty and gives you a slightly fuller sound that gets split as soon as you plug anything into either S/R jack.

It doesn't have any impact on the parallel dry path that is persistent when the loop is occupied. Maybe that was different back in the day
 
#9
rickdiculous said:
That's what I'm saying. The jumper, which is present in both of my MarkBass heads, only affects the behavior of the loop when not in use. It essentially connects the tips of the send/return jacks when empty and gives you a slightly fuller sound that gets split as soon as you plug anything into either S/R jack.

It doesn't have any impact on the parallel dry path that is persistent when the loop is occupied. Maybe that was different back in the day
Click to expand...
I know this, that's why I mentioned that a few models had an ADDITIONAL jumper that yours DOESN'T have.
 

Latest posts

Top Bottom
Back