OT as Ext. Audio Effect losing 2.5 dBFS

[natar]

I’m setting my Octatrack MkII up to both play into and record from my DAW (Live 11). I have an audio track that peaks at -13.5 dBFS that I’m routing to OT AB as an insert effect. When I enable the effect, the audio comes back in at 16 dBFS.

I tried:

• No master track, MAIN OUT is at +0, using balanced cables
• Using a Thru machine with AB GAIN at +0, SRC VOL at +0, and AMP VOL at +63, no FX enabled
• Using a Thru machine with AB GAIN at +0, SRC VOL at +63, and AMP VOL at +0, no FX enabled (clipping somewhere)
• Using AB DIR at 127 with AB GAIN at +0
• Using another DAW (Bitwig)
• Input and output trim in my audio interface (MOTU 16A) at 0
• Running everything hard panned left to make sure it wasn’t a pan law/stereo thing

I can add makeup gain at a few different points but want to make sure I’m not overlooking some aspect of the end-to-end gain staging. Anyone else run into this?

[sezare56]

Track Level should be at 127 for Thru tracks…

[natar]

Sorry, forgot to mention, track level at 127 for the thru tracks ‍:dizzy:

[Schnork]

My OT has slight level difference between left and right main outs. What’s the level when you pan all tracks right?

[sezare56]

@natar

I have an audio track that peaks at -13.5 dBFS that I’m routing to OT AB as an insert effect. When I enable the effect, the audio comes back in at 16 dBFS.

What is the result if you skip OT and go back directly ?

[sezare56]

Signal flow/gain staging diagram for Octatrack MKII

Is there a signal flow or block diagram for the Octatrack MKII? I found lots of text but no diagrams, so here’s my attempt trying to visualise the level & volume controls if it’s any use. The lines show possible connections; they’re not all active at the same time. Am new to the machine so just feeling my way here

[sezare56]

2nd question : what is the result without hard pan ?

[natar]

Thanks both for the troubleshooting ideas!

@sezare56

What is the result if you skip OT and go back directly ?

Great idea, I don’t know why I didn’t think of this, but the MOTU has configurable routing. When I route the ext. audio outs directly to the ext. audio effect returns in hardware, the level stays consistent.

@Schnork

My OT has slight level difference between left and right main outs. What’s the level when you pan all tracks right?

@sezare56

what is the result without hard pan ?

But I still lose a little volume routing through the OT without hard or panned hard right (good idea also!).

@sezare56 thanks for the gain staging thread link as well. Both your and @philtipping’s diagrams were very helpful. I really don’t think I’m missing anything. Since I’m noticing a difference with just AB DIR at 127 I suspect it’s not a setting somewhere, but some other thing I’m missing.

[sezare56]

@natar

the MOTU has configurable routing. When I route the ext. audio outs directly to the ext. audio effect returns in hardware, the level stays consistent.

I’d rather use the same cables instead of internal routing…

[natar]

@sezare56

I’d rather use the same cables instead of internal routing…

Oh wow, thank you!! That was a good call. When I plug the outs back into the ins the volume drops 1.5 dB. Tried a couple different cables too. I guess I’ll go ahead and add a bit of makeup gain in the chain.