Transparent Volume Attenuator Pedal for 100 Ohm Line Output Signal?

[Lumberjack]

I have an unbalanced and linear line output signal that I want to attenuate before it hits my guitar amp with a 1M Ohm input impedance.

Is there a pedal design out there that would allow me to transparently decrease my volume by about 60% of what it is now?

 

[KrIVIUM2323]

Hi,
What is your line out reference level? +4dbu, -10dbu?

I often use stompbox with my hardware synth or sampler. The 'standard' from modular synth world is +/- 5v output ( 10v pk/pk so approximately 12/13dbu ) so i decided to use a -26db attenuation.
For this i use a simple resistor divider with a 20 ratio, which is a 20k resistor and a 1k resistor. Output impedance is circa 1k ohms ( 952 ohms to be accurate) and is ok as we are into 'bridging' case ( we try to reproduce a voltage without modifying freq response so out impedance should be at least 5/10 time lower than input Z, with a 1000 ratio with your amp it'll be more than ok).

If you need to compute ratio/db in case this is too much or to low attenuation (guitar signal is often assumed to be 1v pk/pk):
Attenuation needed: 20log(20)=26db
Out z: (r1xr2)/(r1+r2) = (20k x 1k)/ (20k + 1k) = 952r

For my soundcard which output +24dbu i choose -36db. Replace 22k with 64k resistor, out z is then 984r.

 

[merlin]

I have an unbalanced and linear line output signal that I want to attenuate before it hits my guitar amp with a 1M Ohm input impedance.

Is there a pedal design out there that would allow me to transparently decrease my volume by about 60% of what it is now?

Like Kr said, you can just use a simple divider or a 5k pot to do that job.