External Audio Effect returns dead via ADAT between two focusrite 18i20s - metering shows signal but no audio. I'm stuck on this and it's driving me nuts. I have insert effects working fine on my main interface but can't get the same setup working over ADAT to my second interface.
My rig:
Abelton Live 12 Suite Windows 11 64bit
Scarlett 18i20 4th Gen (main interface to PC), Scarlett 18i20 3rd Gen, Scarlett OctoPre
ADAT chain:
OctoPre out → 4th gen ADAT in 2 4th gen out → 3rd gen ADAT in 1 3rd gen out → 4th gen ADAT in 1
What works: I have an H90, Meris Mercury X, and Chroma Console plugged into the 4th gen's analogue I/O on 3/4, 5/6, 7/8. These all work as insert effects in Ableton no problem. I also have three synths on the OctoPre and they work fine as external instruments.
What doesn't work: Using Two Warm Audio EQP-WAs and a 2MPX on the 3rd gen 18i20 as insert effects configured the same way as the pedals above. The audio registers in the audio to, but not the audio from.
Physical connections:
EQP-1: out 3 → in 3 EQP-2: out 4 → in 4 2MPX: out 5/6 → in 5/6
Routing config: 4th gen digital outputs in Focusrite Control 2:
ADAT 3-4 → Playback 13-14 ADAT 5-6 → Playback 15-16
3rd gen in Focusrite Control:
Line outs 3-4 sourced from ADAT 1.3-1.4 Line outs 5-6 sourced from ADAT 1.5-1.6 ADAT outs 1.3-1.4 sourced from Analogue 3-4 ADAT outs 1.5-1.6 sourced from Analogue 5-6
Ableton I/O config has 13/14 as mono (EQP 1 and 2) and 15/16 as stereo (2MPX).
External Audio Effect set to send 15/16, return 15/16:
Send metering shows signal going out (peak around -4) Return metering shows signal coming back (peak around -3) But zero audio passes through. Sound cuts out completely when I enable the effect. I can hear ground hum on the returns so the physical path is connected. Tried phase invert, nothing
The weird part is the meters show signal is coming back, but I can't hear it through the External Audio Effect OR by monitoring the input directly on a separate track. What am I missing?
Since the pedals on the 4th gen work fine as inserts, but the 3rd gen stuff doesn't, I figure it's something with how the 3rd gen is sending audio back over ADAT. The 3rd gen receives from the 4th gen fine (send path works) but something's broken on the return.
Is there a routing step I'm forgetting in the 3rd gen's ADAT output config? Clock issue maybe? The octo pre is the clock master. Running 48kHz. Focusrite Control 2 for 4th gen, legacy Focusrite Control for 3rd gen.
Happy to answer any questions you have. Thanks for taking a look.
Troubleshooting Outboard Hardware as Insert Effects
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Pantsareforwimps
- Posts: 1
- Joined: Sun Feb 15, 2026 4:52 am
Re: Troubleshooting Outboard Hardware as Insert Effects
Since the effect chain on the 4th Gen works, it is safe to assume you have the configuration settings worked out.
The first thing I would suggest is to use a patch cable and plug the send output on the 3rd Gen back into its input. Make it as simple circuit as possible.
Next I would look at the Focusrite control program (I forget what it is called) and make sure the internal routing is correct.
You have a lovely pedal collection. :^)
good luck
dsu
The first thing I would suggest is to use a patch cable and plug the send output on the 3rd Gen back into its input. Make it as simple circuit as possible.
Next I would look at the Focusrite control program (I forget what it is called) and make sure the internal routing is correct.
You have a lovely pedal collection. :^)
good luck
dsu