Rational Acoustics



Dr. J
May 16th, 2013, 01:05 PM
Hi guys -- thought I would spark up another topic on microphones. Is there a valid reason why you would swap out your measurement mic for say a SM58 as a finisher to tuning a system? I have read a few articles over the last year that talk about it but never really understood the exact reasoning. Bob McCarthy mentions it in his book but it seemed it was a specific troubleshooting technique based on the type of singer.

I have measured my system using a measurement mic -- took a snap shot pic and stored it -- typical curve for a system...etc. I then placed a SM 58 in it's place and fired it up.... interesting observations... #1. The signal level was much lower so I relocated the trace upwards so it would overlap the previous trace.... #2. The 58 had more roll off in the low frequencies -- no problem there. #3. Starting at 2.5kHz to 4.5kHz a pretty decent bump up in the area. #4. Other than those two areas a SM58 is Smooth in response.

Would there be any reason to level the higher area out with the 58? Is there anything to learn from this?

On occasion -- I run sound for a band where a girl basically refuses to stay on the mic. She also can't hear herself as well (imagine that - may try IEM with her) and to top it off she is what I call a "whisper" singer who wants everyone to hear all of her little "breathy" phrases and so forth. Needless to say -- I have her gained up. I use a 58 on her because she sounds better with that mic than a beta 58. I also think a mic with better rejection may help - which the beta has -- It just doesn't seem to be the right mic for her. What you all think?

Arthur Skudra
May 16th, 2013, 03:21 PM
689

Maybe I'm missing something here, but why on earth would you want to use a shaped response microphone to tune a sound system???? The only time I'd use a vocal mic for sound system optimization is during the final step of ringing out stage monitors, and that's after having optimized the system using flat response omnidirectional measurement microphones!!

Dr. J
May 17th, 2013, 08:11 PM
689

Maybe I'm missing something here, but why on earth would you want to use a shaped response microphone to tune a sound system???? The only time I'd use a vocal mic for sound system optimization is during the final step of ringing out stage monitors, and that's after having optimized the system using flat response omnidirectional measurement microphones!!

Thanks for your answer Arthur! Does anyone else think of a valid reason to use a vocal mic to measure with? Of course as a final measurement..... Thanks!

Harry Brill Jr.
May 18th, 2013, 12:56 AM
No valid reason to use a vocal mic to tune a PA. Vocal mics have a particular response to help push the vocal intelligibility forward. If you tuned your system with that mic you would actually decrease intelligibility. The mic would have the inverse affect.

You should try the KSM9 on your singer. Set it to super or hyper (whatever it is) rather than cardioid. I'm sure others will chime in here on other mics. Hi pass her around 150, and low pass her around 8-10K. Coach her on her mic technique. She should not be eating the mic, but also shouldn't be holding it a foot away unless she's really belting it out.

Rasmus Rosenberg
May 18th, 2013, 08:35 AM
+1 only you will get way longer with words and confidence than gear, in a situation like that. Get her and the band on your side, once they got a little confidence that you there to help them get a killer show (where you can hear the lyrics :cool:) it will be a lot easier. Confident "baby steps" with out too much tech talk is the way to go.

One skill I think that a lot of us live mix techs, is overlooking, is how the heck music is "created" now a days. If you have any musicians in your network, spend some time with them to see how it works. Once you figure out that what the try to recreate, is sitting at home and whispering into the mic, then process it to "hell" in a DAW, you IMO at least have a better chance of knowing where they want to go. The hard part is off cause to translate that to a live setting, but really a point where YOU can make a difference (and get a lot of work if you good at it). It might be a simple as just splitting the Lead mic one more time for some extra processing or what ever. Its worth digging into, as you know a lot of this is seems almost impossible to get right at an one off. But with a little preparation and research you can be prepared for a lot more.
On the tech side we are so lucky that the Laptop is now able to help out so much, its never been easier to carry processing than now. A mic kit and a laptop with a few plug ins and your starting point has been lifted to new standards.

An other recommendation for Ksm9. I have found that you can change the windscreen, (i use a beyer, with heavy foam) that reduces the distance to the capsule almost to half and gives about 4db more gain. With a female singer with a high HPF the added proximity effect is not a problem, and I use some heavy foam to balance out the added breathing effects, it dolls the response a little, but still has a very nice HF compared to a 58 (now its just not so over hyped). The handling balance of the mic is also improved.

As for using a 58 for measurement mic, hmm i can only think for examples where you use it to "mic compare" with, not to tune a system with. I can be useful in a monitor situation to see what "gets" through a 58 vs a omni, but I have never actually found ways to use it. Monitor sound is IMO such a different animal, a lot of what measures really bad like multiple arrivals and huge peak and dips are what makes it rock up there. Thats not to say its random, optimization technics can be implemented to great effect, but your way more on the artistic side up there.
mvh
R

Ben Clarke
May 29th, 2013, 08:08 PM
Used vocal microphones into Smaart heaps of times... well, 5 or 6 times i can remember

1. Didnt have my test kit with me, but did have my laptop (i just turn up to installs sometimes, then get asked the inevitable "hey, we're having trouble....")
2. Gain check of different sources
3. Phase check of different sources (not judging the phase trace data itself, just how it compares to the next circuit)
4. Alignment (comparative measurement remember)
5. Used my ears for frequency response... they're good at that.

Incidently, i remember one room quite well. I ended up back there a couple of years later with the same rig and recalled getting better coherence with the vocal mic. This particular room has a terrible acoustic response. Vocal mic was hypercardioid.

Id categorise an SM58 as a crazy weighting curve in all of the above. i dont care if i know whats going on.

Chris Johnson
June 14th, 2013, 04:42 AM
A 58, or other directional mic is a great tool for time alignment in cases where there is a high level of background noise, and you aren't in a position to make lots of noise out of the PA

Its also useful for things like sub-top phase alignment in the same situations.

So no substitute for a measurement mic, but in certain 'in-the-trenches' situations, it can be another tool in the toolbox

jonnip
June 22nd, 2013, 03:40 PM
another big +1 to the KSM9

markamcfarlane
July 20th, 2013, 04:28 AM
... and I use some heavy foam to balance out the added breathing effects, ...
R

Ramsus, what kind of foam do you use, and where are you getting it? I have a couple very old discontinued mics that need to be reformed, the original behind-screen foam has completely disintegrated, as well as the little foam disk directly on the capsule.

Rasmus Rosenberg
July 21st, 2013, 04:47 PM
In the case i was referring to it was just some leftover speaker grill foam from some Nexo speakers, nothing fancy. Im pretty sure you can order new foam from the manufactures and that they can advise.
/R

FILO4PRES
January 3rd, 2014, 12:20 PM
Great topic,

System tuners have ben using vocal/speech microphones to optimize systems for a long time. For example the old timers and their TEF machines would grab a pulpit/lectern mic and create a curve to offset the frequency response of the microphone. Also notably by Bruce Jackson RIP (Barb Streisand/Elvis/The Boss/ creator of LAKE) used to do this for Barb Streisand and a custom Rhodes mic I believe.

I do this at the tail end. Use the lectern microphone and optimize for GBF but using the console eq not the system eq.

The SM58 has a large bump above 3k to compensate for a loudspeaker who's response was less than ideal at those frequencies a long long long time ago. It was either a Western Electric or an Altec.
Thats a common problem with CD horns not so much now that we live in a conical/line array world.

@Mark McFarlane
Depending on where you are in the middle east there are some great case manufacturers. Dubai in Jebel Ali for example does some great work by Indian craftsmen.

best-

Josh

Brendan Venter
March 11th, 2014, 07:37 AM
I do this at the tail end. Use the lectern microphone and optimize for GBF but using the console eq not the system eq.

Hi Josh,

Do you care to elaborate on this technique?

Thanks.