How to set the delay locator to measure a subwoofer in Smaart [GSwSST29]

After you have practiced measuring a full-range speaker, the next step is to measure a subwoofer in Smaart. It turns out to be a little more tricky, but I've got some ideas to help you.
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I love to geek out about the physics of sound. This channel focuses on the growing opportunity for live sound engineers to improve their confidence and consistency through the understanding of the principles of sound system design and optimization. My goal is to make this channel upfront and honest about my success and failure, so you can learn from both.
I am always open to suggestions and feedback so please comment on this video or contact me through my site.

[@fronbasal]

This was by far the most intuitive video about delays I could find on TH-cam. Thanks for sharing this publicly, a great resource! ❤

[@stefanmplayer]

Hi Nathan, thank you so much for making all these video’s publicly available! They are a great help for someone like me who’s relatively new to using Smaart for actual system tuning both to acquire new concepts and as a reference since I tend to forget some things every now and than due to not doing this on a daily basis🙏🏼

[@nathanlively]

Great to hear! And to be honest, half the reason I make them is so that I can have go back and look in case I forget. ;)

[@user-ki7nq3bi3k]

For those who did not know where the wrap around 10 milliseconds came from just like me. Frequency itself vibrates 100 cycles per second (100Hz). Therefore 1 Cycle should take 1/100 seconds to complete. While 1 second = 1000 milliseconds. 10ms is the time for frequency 100Hz to complete one cycle.

[@nickevansaudio]

Great vid thanks Nathan!

[@Whats_Your_Purpose]

Nathan, would it be possible to just extend you xover temporarily to 1000hz or so to get a better lock from hi frequencies thru sub?

[@nathanlively]

Hi Ronald. Yes, it is possible, but not recommended. Adjust the low-pass filter will not give you accurate results on the phase graph. Try it out. Measure the sub with the LPF in, then out.

[@cscrignaro]

Ahhhh, I just finished calibrating my surround room and just seen this video. Ended up setting the LFE to 0 delay so that my graphs weren't all crazy. I'm mostly concerned with the magnitude trace, so I think it is okay if the coherence is slightly off. Do you think I should recalibrate the LFE with the correct delay setting? But I'm also not looking for a specific cross-over frequency since the LFE channel is it's own channel. What do you think?

[@nathanlively]

Hey Carlo, I'm not sure. If the LFE channel is not coherent to any of the other channels, what would you align it to?

[@cscrignaro]

@@nathanlively Just needs to be +10dB of in-band gain from the main channels. I guess the only time it would really matter is if I was using bass management.

[@lowbass5]

Hello Nathan, every X32 has the .85 ms delay? I wonder because I have a weird situation , my subs physically are behind the mains, physically .35cm , after smart alignment I have .90cm (overlap at crossover point) instead of the physical .35cm ..., does smaart take in consideration the board and the processor delay ? I am not using smaart delay, just reference and that’s it.

[@nathanlively]

Hey lowbass5, I don't know about every X32, just mine. :)
I'm not totally clear on your question. Maybe you could making a drawing for me?
0.35 centimeters is 3.5mm is only about 1ms. Have you tried just putting your main on the ground right next to the sub to see if they are in alignment natively with no changes?
Smaart is just a dumb machine. It doesn't know or care what you have in line. It will measure whatever you pass the signal through. If you run your reference loop directly from the output of your audio interface back to the input and the measurement signal through the X32 to the speaker, then yes, you are measuring the X32 and the speaker.

[@dominikkriss1853]

Hi Nathan, is there any reason why you are pointing measurement mic to the ground in around 45 degree? I was wondering about mea. mic placement when alligning sub to mains, so far i used to just lay it on some foam on the ground.
my consideration:
- on stand, pointing to ground at 45deg, tip nearly touching ground - getting mainly reflections of ground, no direct sounds
-on foam, on ground- 50/50 reflections and direct sound (for me it feels like the most natural usage)
- on stand, pointing up at 45deg, tip few cm above the ground - getting mainly direct sounds , reducing reflections of ground
I think it does not matter when measuring just subs, but it may have significant coherence impact when measuring also mains.
what do you think about mic placement?

[@nathanlively]

Hey Dominik, thanks for checking out the video. I have an article coming out soon that covers lots of mic placement questions, but here are my thoughts about mic height:
Head-height or ground plane?
Head-height is preferred since it most closely matches the listener's experience, but should be abandoned for ground plane if actionable data is heavily compromised by floor reflections. Keep in mind that changing height will also require a change in depth. For example, if you decide that you want to measure at ¾ depth, consider a line from your main that intersects with your mic and then the floor and move back to this position.
If you are measuring ground plane on a floor that is not ideal for reflections (eg. full of chairs), consider using a 0.5ft2 (0.15m2) reflective panel like plexiglass to preserve high frequencies. Or, simply ignore the HF response during your crossover alignment, then move back up to head height for other calibration processes that focus on the HF.
Does that help? Or did you have a different question?