External pedals FM9

  • Thread starter TheElaborateDream
  • Start date
I came across this thread while researching a solution to having trouble getting sound when trying to add an external drive pedal via a simple loop. Similar path to what andyt has above, however with no sound when Out 3 and In 3 blocks are engaged.

After the In 1 Block, I added Out 3 and In 3, with connector shunts. TS cable from FM9 Out 3 L to the input of my external drive, then external drive out to FM9 In 3 L. When In 3 Block is engaged, I get no sound. There's no signal going into the external pedal. Interestingly, when I bypass In 3 Block, I have sound (and I coincidently see there's still no signal routing through my external pedal). The signal appears as Thru sound, and it's definitely not going through my drive. What am I missing?

Image 5-17-23 at 11.47 AM.jpg


While I'm solving the above, I have a second question: Is it recommended to add such an external (drive) pedal before In 1 or after? Was thinking that a quick, interim solution to my above problem may be to simply put my drive in front of the FM9.
 
Before input 1 would be simpler, but you run the risk of overdriving the input since you would presumably be setting the input sensitivity to match your guitar.

No reason not to put it in loop 3, but you need to remove the shunt between out 3 and in 3 on the grid. That connection is made externally with the drive pedal.

Also check the levels of out3 and in3. Out 3 has a knob on the FM9 front panel that should be all the way up (0dB), plus an output level in the block. In 3 will have an output level inside the block as well.
 
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elvis said:
Before input 1 would be simpler, but you run the risk of overdriving the input since you would presumably be setting the input sensitivity to match your guitar.

No reason not to put it in loop 3, but you need to remove the shunt between out 3 and in 3 on the grid. That connection is made externally with the drive pedal.

Also check the levels of out3 and in3. Out 3 has a knob on the FM9 front panel that should be all the way up (0dB), plus an output level in the block. In 3 will have an output level inside the block as well.
Click to expand...

AxeFX III user here but going to hijack this as I assume it is equally relevant for the FM9.

I feel like drive pedals sound/behave differently in the loops than they do in front of the unit. However, I don't have the ability to switch the configuration fast enough to test in what I would call a truly accurate A/B. So, admittedly very poor test.

Based on the hardware of these units, is there any reason to think that drive pedals SHOULD sound/behave differently in the loops than they do into the front?

If not, I'm going to just assume any differences I think I notice are due to my inadequate testing.
 
AmbientOwl said:
AxeFX III user here but going to hijack this as I assume it is equally relevant for the FM9.

I feel like drive pedals sound/behave differently in the loops than they do in front of the unit. However, I don't have the ability to switch the configuration fast enough to test in what I would call a truly accurate A/B. So, admittedly very poor test.

Based on the hardware of these units, is there any reason to think that drive pedals SHOULD sound/behave differently in the loops than they do into the front?

If not, I'm going to just assume any differences I think I notice are due to my inadequate testing.
Click to expand...
This is common. When a pedal is first in the chain, it is driven by the guitar directly, which has a high-ish output impedance. This interacts with the pedal's input impedance. Farther down the chain, you get one pedal's output impedance interacting with the next pedal's input impedance. Pedals vary, and pedal output impedance can run from 150 Ohms or so to a few kOhms. Pedal input impedances can run from a few kOhms to a MegOhm or more.

FM3 (and I presume Axe III) input impedances are 1MegOhm for all 3 inputs. Output impedance is 600 Ohms for all outputs. In particular the 600 Ohm output impedance will drive your pedal quite differently from what your guitar or other pedals might do. You can actually accommodate for that by adding a resistor between the FM9/AXE III loop output and the pedal input. There are products like the Radial Dragster for this sort of thing as well.
 
elvis said:
This is common. When a pedal is first in the chain, it is driven by the guitar directly, which has a high-ish output impedance. This interacts with the pedal's input impedance. Farther down the chain, you get one pedal's output impedance interacting with the next pedal's input impedance. Pedals vary, and pedal output impedance can run from 150 Ohms or so to a few kOhms. Pedal input impedances can run from a few kOhms to a MegOhm or more.

FM3 (and I presume Axe III) input impedances are 1MegOhm for all 3 inputs. Output impedance is 600 Ohms for all outputs. In particular the 600 Ohm output impedance will drive your pedal quite differently from what your guitar or other pedals might do. You can actually accommodate for that by adding a resistor between the FM9/AXE III loop output and the pedal input. There are products like the Radial Dragster for this sort of thing as well.
Click to expand...

Thank you for taking the time to explain this. For some reason this is the first time it's actually clicked for me despite digging through so many threads about using external drives. I think my lack of knowledge about electronics (impedance, etc.) impairs me a bit.

Ultimately still should let the ears be the guide, but I'm happy to hear there may be a true, physics-based reason I am hearing what I think I'm hearing and that it all isn't just a psychological trick.
 
elvis said:
This is common. When a pedal is first in the chain, it is driven by the guitar directly, which has a high-ish output impedance. This interacts with the pedal's input impedance. Farther down the chain, you get one pedal's output impedance interacting with the next pedal's input impedance. Pedals vary, and pedal output impedance can run from 150 Ohms or so to a few kOhms. Pedal input impedances can run from a few kOhms to a MegOhm or more.

FM3 (and I presume Axe III) input impedances are 1MegOhm for all 3 inputs. Output impedance is 600 Ohms for all outputs. In particular the 600 Ohm output impedance will drive your pedal quite differently from what your guitar or other pedals might do. You can actually accommodate for that by adding a resistor between the FM9/AXE III loop output and the pedal input. There are products like the Radial Dragster for this sort of thing as well.
Click to expand...
Thanks for sharing this info. I am in the middle pf a FM9 pedalboard build, and I'm planning to put a tuner, Digitech Drop, and a couple drives before the input of the FM9. I was contemplating running the drives in a loop, possibly to control them with the FM9, but decided to just run them inline into the front. I won't be using them that often, and can tap dance a little LOL. It's the easiest wiring solution as well, and hopefully tonally/feel wise the best choice as well. We will see.
 
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