FM3 Latency?

C

caballero59

Inspired
I received my FM3 and began using Reaper all at the same time so the learning curve is pretty steep. I have disabled the latency auto detect. The output offset is also set to zero. I record one hit from a snare in Reaper and then patched the headphone output on the FM3 to the Input 1 block. The Input 1 block is connected to the output 1 block with no processing in between. I'm needing approximately 1500 samples to get the wave forms to line up (30 mili seconds of latency?).

Furthermore, the two wave forms are identical in the beginning and then begin to stray from one another, indicating the copy is not perfect.

Probably need to take a class on this setup.
 
Depending on your buffer settings, 30ms for round trip latency is somewhat high but not out of the question. If your DAW system can handle it, you may be able to lower the buffer size to reduce the latency.

You can also do loop back via the other USB input and output channels, so there's no need to physically patch the loop back. For the FM3, you'd send your track output in Reaper to USB Outputs 3 and 4 to send it directly to back the Input 1 block. You'd then record the results on USB Inputs 1 and 2 (the Output 1 block L and R) like normal. This is exactly how reamping works via USB as well.

Keep in mind that if you monitor your playing directly from the FM3's outputs (monitors or headphones), you'll hear the grid output with no latency at all, and you can turn off software monitoring of the input in Reaper to avoid hearing the signal doubled. Any playback latency of the rest of the tracks is trivial when playing along as long as you are not trying to direct monitor the input signal via software.
 
mr_fender said:
Depending on your buffer settings, 30ms for round trip latency is somewhat high but not out of the question. If your DAW system can handle it, you may be able to lower the buffer size to reduce the latency.

You can also do loop back via the other USB input and output channels, so there's no need to physically patch the loop back. For the FM3, you'd send your track output in Reaper to USB Outputs 3 and 4 to send it directly to back the Input 1 block. You'd then record the results on USB Inputs 1 and 2 (the Output 1 block L and R) like normal. This is exactly how reamping works via USB as well.

Keep in mind that if you monitor your playing directly from the FM3's outputs (monitors or headphones), you'll hear the grid output with no latency at all, and you can turn off software monitoring of the input in Reaper to avoid hearing the signal doubled. Any playback latency of the rest of the tracks is trivial when playing along as long as you are not trying to direct monitor the input signal via software.
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Very helpful. Thank you!
 
If I can ask one more thing. Is it even valid to to connect the headphone output to the Input1 block (set to Analog) of the FM3? I'm trying to visualize the signal flow here,...does the waveform from the DAW come in on USB 1&2 (in), is then routed to the Headphone output which is then patched with a cable to the Input1 block, and then output back to the DAW on USB 1&2 (out). Does this create some weird signal entanglement?
 
Yeah USB Outputs 1 and 2 from the DAW get mixed into Output 1 on the FM3 and Axe III. That happens just before the headphone and output jacks, but after the Output 1 signal gets sent to USB Inputs 1 and 2 for recording. Connecting the headphone jack to the inputs creates a direct feedback loop that will likely go into oscillation at some point if signal flows through the grid unimpeded. That's likely why you saw the waveform start to change in the re-recorded copy. That feedback loop would just keep adding more and more copies of the signal until it clips and/or oscillates.
 
Again, very very helpful. Are you aware of a signal flow diagram for the FM3? That would be very helpful as a reference to save in my notes.

Thanks again for your help.
 
caballero59 said:
Again, very very helpful. Are you aware of a signal flow diagram for the FM3? That would be very helpful as a reference to save in my notes.

Thanks again for your help.
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Signal flow is straight forward. USB audio from the computer goes to Out 1, which is both the physical Out 1 jacks and Headphone jack.

From there, how you route in the preset determines routing.

If you choose to send Output 1 (headphones or XLR) back into Input 1, then back through Out 1 again, you create a feedback loop.

Out to In to Out is a direct feedback loop in any system
 
There's a flow diagram on the last page of the Axe FX II manual. I believe the signal flow is very similar in both the FM3 and Axe FX III as well but with additional USB and Analog outputs. I've not seen one anywhere specifically for those two.
 
Not sure but I'm using this to flesh out a flow diagram based on the information you gave me in post 6. It really helps me to see the overall picture. Your #6 post immediately revealed to me why my circuit wasn't working because of feedback.
 
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