How to find a polarity inversion using Smaart® [GSwSST32]

To verify polarity using Smaart:
1. Set delay finder to auto tracking.
2. Start signal generator playing through all speakers.
3. Place microphone close enough that you can take an isolated measurement.
4. Store trace and verify matching phase and impulse response.
5. For sub, disable delay auto tracking.
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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.
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Smaart® and the Smaart logo are registered trademarks of Rational Acoustics LLC and are not affiliated with Nathan Lively or Sound Design Live.

[@user-qn2bg7xt6n]

Very good suggestion sir

[@kosmicken]

Does this work for far field measurements? I tune cinemas with Smaart, and measurements are done with mics at the seats. I generally use the RTA to check polarity by making sure that multiple channels add rather than subtract. But it's always cool to learn new tricks.

[@nathanlively]

Hey Ken, I don't have a great answer for this question. I have never made it work myself.

[@BhavikPatelhr]

How we can identify polarity inversion in REW?

[@nathanlively]

Similar stuff. In the IR window, look for peak up or down. In the phase window look for matching slopes that are 180º apart. There's even a button to invert the phase so you can see the difference.

[@sabrewolf2181]

ciao nathan ho visto il video bellissima spiegazione ,pero ho visto che dove avevi l inversione di fase prima a 125 hz ora c e l hai a 63 hz o sbaglio ???

[@nathanlively]

Hey Sabre, it's been a while since I filmed this. I initially thought the phase offset at 63Hz was due to the distance offset of my measurement microphone, which could have been fixed by simply adding delay to the to the main speaker instead of a polarity inversion. So this may not have been the best demonstration of a polarity inversion, but I'm having trouble remembering exactly how it was set up.
Anyway, thanks for catching that! :)

[@venkatg3988]

Sir, IAM using 3way cp750 processor. How to measure xcurv for each 1channel. For ex: 40khz to 100kzh mid range, 100 to 2hz HF range, 2hz to which LF range. Pls guide to me.

[@nathanlively]

You just want to measure the processor itself?
This may help - ua-cam.com/video/QwOaqTKvFuk/v-deo.html

[@FreeKeenan]

How do determine it's a positive polarity from a negative polarity? This is still all alien 👽 to me.

[@nathanlively]

Hey Ricky, it's a binary option so you've got a 50/50 chance getting it right. If your two sources don't sum correctly and the phase slopes match but are not on top of each other, it may be a polarity inversion problem.

[@FreeKeenan]

Is sloping down 1st positive or negative polarity? 🤔

[@dominikkriss1853]

Hi Nathan, for polarity checking im using very handy android app,(i believe its also for apple), it is called polarity checker: play.google.com/store/apps/details?id=com.dwa_ict.polaritychecker&hl=en_US
you just need to have 2 devices, on serves as generator, second as analyser. Generator just generates pulses at choosen freq, so first device must be plugged in to mix. Another device uses phone mic to measure pulse at speaker grill, therefore it is "wireless".
For me its handy as there are always some old smartphone around ;) and you dont need to walk around whole area with mea. mic, all you need to to is point your"wireless" phone mic to speaker.