Marshall DSL100hr fx loop vol drop

Ramo

Ramo

AmTHRASHador of Chugz
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hi guys

my dsl100 hr got vol drop when fx loop is activated. i use delay and chours in fx loop most of the time chorus is off just delay on. when i kick it in for lead parts i hear vol drop,. Does dose anyone have the same issue with this amp? any ideas how to fix it? i dont have another delaY pedal to try to see if its a pedals fault.

many thanks in advance.
 
Ramo said:
hi guys

my dsl100 hr got vol drop when fx loop is activated. i use delay and chours in fx loop most of the time chorus is off just delay on. when i kick it in for lead parts i hear vol drop,. Does dose anyone have the same issue with this amp? any ideas how to fix it? i dont have another delaY pedal to try to see if its a pedals fault.

many thanks in advance.
Click to expand...

The problem is not the amp, I am thinking.

Plug a guitar cable between send and return. No pedals.
Does the volume drop now, or does it stay normal?

The actual issue is a mismatch of levels - the level coming from the pedal output to the effects return. This level is low level (guitar level).

Marshall amps have always been known for the poorly deigned effects loops, that do not match USA effects pedals.
However, there is ways to modify or compensate for the problems.
 
I tested
Amp Mad Scientist said:
Usually there is something you can do...
Click to expand...

I tasted it today i put guitar cable from send to return( same one) and it was fine . Then i tried with pedals on vol would drop then with off pedals still would drop. You ate right its pedals amp is ok. So how do i go around it?
Thanks
 
Ramo said:
@Amp Mad Scientist

hello mr Amp mad scientist

my apm was playing up , is it tubes are getting old ir something else? After that amp was fine.
View attachment 48115
here is the video
Click to expand...














You need to raise the level of the last pedal in the effects chain.
Marshall amps have never been known for matching pedals very efficiently.
This is not an unusual problem.

What is the last pedal in the chain?
And can we get a schematic for it?

Or you can use some type of buffer amp, to fix the level problem.

1598996244141.png

1598996402883.png

Or
you can modify the effects loop of the amp but I don't have the schematic for that model.
 
Last edited:
That is if this schematic is true, you should be able to adjust SV2 for a loudness level correction.
And if that's not enough, you should be able to change R11, increase the ohms to raise the audio level.
Right now R11 is 1K.
But you should be able to make that R11 into 4K7 or more, to realize a loudness increase.
 
Amp Mad Scientist said:
That is if this schematic is true, you should be able to adjust SV2 for a loudness level correction.
And if that's not enough, you should be able to change R11, increase the ohms to raise the audio level.
Right now R11 is 1K.
But you should be able to make that R11 into 4K7 or more, to realize a loudness increase.
Click to expand...
Ill open it up tomorrow and see whats going on there ill take pic ...

You lost me with R11 is 1k i have no idea what you are saying , sorry man :)
 
Ramo said:
Ill open it up tomorrow and see whats going on there ill take pic ...

You lost me with R11 is 1k i have no idea what you are saying , sorry man :)
Click to expand...

R11 is a resistor.

There are different resistors.
Changing that R11 resistor will probably help correct the audio levels.

Identify the resistor by measuring with an ohm meter.
Or, Identify the resistor by the color codes that are printed on the resistor.

------------------------------------------------------------------------------------

Also
The schematic shows an adjustment pot SV2.
If the schematic is correct, you might be able to adjust SV2, to correct the audio levels.
 
Amp Mad Scientist said:
R11 is a resistor.

There are different resistors.
Changing that R11 resistor will probably help correct the audio levels.

Identify the resistor by measuring with an ohm meter.
Or, Identify the resistor by the color codes that are printed on the resistor.

------------------------------------------------------------------------------------

Also
The schematic shows an adjustment pot SV2.
If the schematic is correct, you might be able to adjust SV2, to correct the audio levels.
Click to expand...
i just try open it and i could not find right size tool to open it, need to buy from shop it has weird shape screws..
 
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