Measuring Mic gain level

[Aaronious]

Hi guys,
Posted this question on Rational Acoustics forum but it seems that the forum is not very active as I still haven’t got any response yet. So I hope that you guys could help me out here. Thanks in advance

When setting gains for measuring mic, do I leave it as it is or should I increase it to to match with the ref signal when moving it further back from the speaker? Trying to EQ my system to the room and not sure where to place the mic, using ECM8000 atm. Should I leave it within 1m of the speaker for 1st measurement to achieve good SNR reference then move it to various positions where people will be sitting. Should I just measure half of the room (right if measuring right speaker) or should I place mic on the left half of the room as well? I thought if I cross to the left half, when playing both speakers, I would have some frequency cancellations and hence not a good reading. Do I point the mic at centre stage or to the speaker, but most importantly how loud should the signal be and do I up the gain of the mic when putting further away from the speaker? I tried not adjusting the gain but the amplitude on the graph is not the same for each measurements.
Hope that make sense and any help will be greatly appreciated.

[JimmyB]

If you’re going to use it that way, then matching levels makes sense. I’d use 0db.

[Aaronious]

So are you suggesting to gain up the measurement mic or raise the pink noise level to match the near field measurement? Gaining up to introduce more noise and raising pink noise level would be very loud and unrealistic as the audience at the back won’t be getting same volume as the front at live show. Not to mention causing other issues such as feedback,sound bouncing every where giving lower coherence. So either way is a loose loose situation and I’ve been trying both ways, unsatisfied with the results…still scratching my head. I was told people can tune the room with SMAART in minutes but I’m here stuck at the very beginning with all the contradictions 🤔🤔

[Dick Rees]

You can’t “tune a room” without structural alterations. You can “tune” a system using dual FFT analysis and you can optimize room/system interaction by proper speaker placement, but you cannot alter room characteristics with EQ.

[Aaronious]

I know that there are certain frequencies in a particular room that cannot be fixed with EQ. That’s why I am trying to get very the most accurate readings that represents the room so I could decide what can be fixed and what I should leave alone instead of EQing every peaks and dips. However, the 1st problem I get into is the actual mic settings. Don’t care about placements as I will take tones of readings then average it. It’s just that I not sure if I should increase the mic preamp when moving further away from the speaker or increase the actual output to match the closer one. Both methods I think would not work as of reasons I’ve mentioned above. Even if I have 50 mics measuring at the same time, the gains on those mics would’ve been different so that the readings would sit somewhere along the 0dB area. But that doesn’t make sence as audiences at front and back don’t hear the same volume. Then how in the world would my measurements be accurate enough for me to decide if it’s the speaker or room mode to fix. I hope you guys understand what I’m talking about as I’m about to confuse the heck out of myself too.

[Dick Rees]

Aaron…

To be honest, I really think you’re imagining a lot of things here in regard to how sound, sound systems and acoustics work. Looking back over a live sound and performance career spanning more than 50 years, I can remember when I thought as you do. That was quite a while ago.

If the answers you get don’t seem to fit, it’s very likely the result of the questions you have seem somewhat skewed and mis-directed. No offense intended.

[Aaronious]

Thanks Dick,
Maybe I’m over complicating things. It should come to if it sounds good then it’s good no matter what the graph says on any analysers.

[SteffenR]

btw this is an Allen & heath forum

you should better search for a measurement seminar near you to learn how to use SMAART
but this gives you only the basic skills
interpretation on measurements is an ongoing learning process that never stops

[Dick Rees]

Check your Message folder. I sent you info on “how-to” off-forum as this is the A&H Forums, not Live Sound…as Steffen notes.

Good luck.

[Aaronious]

Thanks guys.
Any input was greatly appreciated. Best forum I’ve every registered, very helpful and quick responses.

[volounteer]

okay please deconfuse me

our church is using the qu32 for live sound
what forum would have better answers for that sort of user

thanks

[Ryan]

@williamadams – I think what they are saying is that the topic OP asked about is a more general live sound question that could apply to any brand of mixer, rather than a question related to working with an A&H mixer.

[volounteer]

@ryan

thanks for explaining that detail i missed.

[volounteer]

@aaronius

Not sure exactly what you are trying to do.

There was a video either here or on utoob about tuning a room and misconceptions some folks have.
google should find you some info if you are specific about what you are trying to do.

it has been a long time but i recall that we had planned at a previous church to set the overall sound level to best fit the audience in that room. we were going to use SPL meters at various places to see if there were spots that were too low or too high. and then try to best compromise the FOH level going to the power amps and then to the speakers.

if you can add speakers or adjust speaker levels you might be able to improve the sound. We had two fixed speakers and our problem was simply loudness level as many folks complained but the preacherman wanted it higher. he increased the gain in his wireless mike which only caused distortion not louder sound from the FOH to the power amps. he did not understand about intelligibility beyond his idea that louder was better.

but to answer your question, based on what i think you said, i would not change the gain but take measurements at various places with the same gain level. then decide what you need to do if anything.

for more general questions try gearslutz or a book aimed at your topic.

[Aaronious]

Volounteer,
Thanks for the reply. I did what you suggested, measuring at various locations without changing the gain. The results looked quite messy on the graph but it still was extremely helpful showing trends of peaks and dips. The best thing was it showed peaks and dips for the same frequency at different locations to prevent me from applying any EQ fixes. SMAART is a great tool if you have an idea of what you’re doing. Takes me less than 15 minutes to tune the system and monitors. I can even use the QU16 as an audio interface to do the test.
Thank you all for the inputs 🤗🤗🤗

[Author]

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