Can I Trust Messy Subwoofer Measurement Data On My Gig?

[@livemixpriyan]

Hey Michal, actually you are adding delay to the reference signal, not to the measurement signal. (@ 3:38). Just for your information: If the Phase slope is going downwards fro left to right, it means: "the Measurement Signal ist arriving later than reference Signal" . (in your case on initial measurement). On this circumstance if you add delay to measurement signal, it's slope will be more steeper.

[@MichaelCurtisAudio]

Yes, thanks for correcting my Freudian slip. Sorry for the mixup!

[@ericdeweese3748]

Just FYI when doing measurements or just using one cabinet when it is next to another cabinet, it is preferred to short out the driver of the adjacent cabinet otherwise the cabinet can basically absorb energy from the working cabinet and mess with measurement data or output performance of the system.

[@MichaelCurtisAudio]

Thanks for the tip, Eric!

[@sonicsound84]

I can't tell you how many times I've brought an outside system in, and the house sound guy will refuse to just turn on his subwoofer amps to dampen them. It's very frustrating. This should be common knowledge.

[@lhenn_]

Nice video! Thank you very much, I've always wondered how to interprete coherence data in OSM! (But can someone please clean that nasty touch display on the FOH table? 😂)

[@jonathanhatchmusic]

I apologize if I missed it, but in this instance where do you land for alignment and EQ of your subs to your mains? If your measurements appear consistent between the mid and back sections would that mainly be what you go by, and would you adjust any EQ at all with how they are responding to the room?

[@MichaelCurtisAudio]

Hey, Jonathan. I didn't cover that in this video since I didn't have access to the DSP. This video was more of a "let me show you a specific measurement phenomenon" more than a "here's how I tuned this system" video. I usually end up aligning subs and mains about 75% of the way back into the audience area. And as far as EQ, I'll apply some to the subs to get the general tonal shape I want out of them if they're not already suited to my target curve out the box, but am usually not trying to overcome any room anomalies since those change in every seat.

[@jonathanhatchmusic]

@@MichaelCurtisAudio gotcha. Thanks Michael! Follow up question then: if you were tuning and adjusting with a DSP, would you then make your adjustments based on the furthest two microphones since they presented very similar data?

[@MichaelCurtisAudio]

Yes I would!@@jonathanhatchmusic

[@sonicsound84]

As they say ​@@MichaelCurtisAudio , the only way you can EQ a room is with a bulldozer! Hahaha 🙂

[@ruslanbatkovich]

Michael, hello. Is there a technique (geometric, algebraic, divine or some other) to correctly place the microphone in space to measure the acoustic system? Thank you in advance.

[@hrmny_]

I think he previously confirmed he's planning on making a video about it, but maybe it's in the backlog

[@benjonestech4981]

The "Correct" place depends on what you're trying to measure. Measuring the front row is the right place for timing front fills but the wrong place to shade the HF of the top boxes of the main array.

[@MichaelCurtisAudio]

@benjonestech4981 beat me to the punch! It's all about what question are you trying to answer. There's general principles for mic placement, but they must be couched within a tuning workflow and framework.

[@ruslanbatkovich]

and????@@MichaelCurtisAudio

[@MichaelCurtisAudio]

@@ruslanbatkovich I cover the topic in depth in my workshop: www.producedbymkc.com/systemtuningworkshop Michael Lawrence also covers it some in this video: kzbin.info/www/bejne/qIeaZ3l3Zs6Un80

[@bmoore4able]

Okay dumb question but why not try to compensate for the room via EQ? Is it position-dependent? Imagine a magic room that uniformly sucked 5dB out of the signal at 300Hz at all listening positions - wouldn’t we boost the signal to compensate? So I’m assuming it’s a non uniformity limitation?

[@MichaelCurtisAudio]

Great question! You certainly can compensate for what a room is doing with EQ, but just making sure that that phenomenon is consistent at every listening postion. In general a room will have more low-mid "buildup" in that many low mids will be coming off the rear and sides of the box and reflecting off walls, but all of those reflections will be arriving at each listening position at differing times and levels. BUT, in general, the listener will perceive more low-mids than just having pure direct sound from the speaker. So often times I find myself taking out more low mids in PAs that are indoors and in reverberant rooms than an outdoor PA.

[@nmawutor]

could you have used the auto find delay tracker instead of manually adding the delay...?

[@MichaelCurtisAudio]

Most analyzers have a hard time finding where to sync the reference with the measurement signal on low frequency information with "auto find" features since there's no real "spike" on the IR. Sometimes they're able to find it, but not always, so that's why I chose to show the manual process.

[@theimunten6325]

to find the 'correct' phase trace, meaning also including the phase shift as it is introduced by the high-end roll off (by IIR filters !) you could manually move the delay compensation to the ONSET of the IR ..(not maximum).. keep up your good work! @@MichaelCurtisAudio

[@MichaelCurtisAudio]

Great point! Thank you so much.@@theimunten6325

[@LeFix07]

another point for your measurement result is the behavior of omni subs placed directly against a hard wall. to get a better bass resposne you should consider to calculate the acoustic center of the subwoofer. with this result you place the sub facing the wall in the calculated distance. Merlijn van Veen devoloped a calculator, that can be used for this purpose and Mathias Huber made a video about it: kzbin.info/www/bejne/fXOoY2Rvma6HhKM

[@MichaelCurtisAudio]

Yes, that's a great point!

[@alanakafang6143]

Tell me you didn't take your measurement with the Microphone resting on the floor? Seriously Dude !!!

[@daanpendavingh3100]

For subs this is fine, it's a halfspace measurement. It is the method to get rid of floor bounce.

[@A1Pro77]

It’s called a near field, half space measurement. It is a valid measurement that we used at JBL Pro all the time.

[@hrmny_]

It's a ground plane measurement, not half space afaik

[@daanpendavingh3100]

​@@hrmny_yeah you might be correct. I think in most cases it is used for the same thing.

[@FOH3663]

They're two different things. - Half Space describes an acoustic loading - Ground Plane describes a measuring approach Right? Perhaps I'm missing something.