Experiences with mic shields?

"so why would we expect the same material to have a measurable impact against transmission of sound as reflections"?

it is a foam process but it would have to be a open cell like pantyhose and speaker cloth. So no, people don't expect the same foam used for speaker grills and wind filters to absorb sound.
 
Reflection filter

Be interested to hear from those who have used and how well it did/didn't work (including of course the circumstances around it...what kind of music being done, what if any other treatments, what mics used etc).

The ONLY one I've found that works is this one: http://www.astonmics.com/halo/
I've used it on location with several different mics in some lousy acoustical situations and it works quite well.
Studio In The Woods - Recording studio in Evart MI - BandMix.com
 
I love the SE Reflexion filter - a very good investment! I record in a room that is not completely sound proof to the outside and I find It blocks a lot of ambient noise. And I am guessing it absorbs some sound from the vocalist that would otherwise bounce off the surface in back of the vocalist and get picked up at the front of the capsule. I get very clean vocal tracks with a United Audio Apollo and a Neumann TLM 103. My only caveat is that the older Reflexion filters shipped with crappy hardware, which has finally been improved.

Guys........BruceKap has the right info. These reflection filters are not so much designed to keep noise OUT of the mic......even though they do help a bit with that. They're designed to keep much of the original vocal from bouncing around the room and back into the mic by stopping it just behind the mic. The less vocal getting into the room....the less the room affects it by reflections.............which do not get back into the mic.
 
I can't tell you how many good vocal takes turned in the mix with those awful plosive sounds. if you can record a vocal with out that go ahead. But, I always have a pop filter on now for vocs. So damn hard to fix it in the mix without screwing up a good vocal take
 
Nothing...he thinks a pop filter is what you mean by mic shield....which is really called a reflection shield, so that's why the confusion for some.
 
Guys........BruceKap has the right info. These reflection filters are not so much designed to keep noise OUT of the mic......even though they do help a bit with that. They're designed to keep much of the original vocal from bouncing around the room and back into the mic by stopping it just behind the mic. The less vocal getting into the room....the less the room affects it by reflections.............which do not get back into the mic.

that makes more sense. keeping the vocal from bouncing around.
Ive never used one might be a good HR bedroom thing or more....a lot smaller than a panel or blanket.
Couldnt you just point the singer at a wall with foam though?

I went through the pics of my son band in the studio and there was that "vocal-wall" there too....never really noticed it. It was a simple setup for the band tracking, 1 mic on the guitar amp (in another room), the bass di to the board, drums had a few mics taking up some console channels.
Then they rolled in the vocal panel and he overdubbed the vocal to the band tracks playback. I remember it was funny they had all these mics and used a SM58 straight to the console, sounded great.
but I guess even there they used the panel to stop the vocal from travelling around the room?

so it seems the bigger the panel the better? in a small room even more important as the vocal would be bouncing giving it that 'drywall box" sound.
 

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I played with the foam piece behind the mic and didnt hear much difference than a piece of foam on the wall. Maybe its the room and all that differences in things. Blankets, foam on the wall, carpet can help remove reflective surfaces aka "sounds bouncing around"

maybe even more valuable for this problem would be a more directional microphone that has a high off axis rejection and low sensitivity...back to the SM7 /RE20....RE15. ..Shure 57/58? 565? live mics more for rejecting noises....

i guess for the sensitive, crisp, condenser mics the room and reflections (vocal booth).

even Frank Sinatra used SM57 and other 58's per SHure site.. dynamics maybe for those reasons of isolation, especially on stage? Queen..Freddie's 565



foam and aurlex gets a bad rap but for tracking and killing bouncing -sounds it works well aka vocal booth.
for mixing and mastering maybe worthless.
 

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You will notice Freddies 'tash is brushing that mic grill? THAT is the 'room killer' aspect of such microphones. NOT the operating principle.

In fact I would bet the better, more expensive capacitor mics have a tighter and cleaner rear rejection factor than many dynamics. Trouble is, without independent acoustic test curves you could never tell. Microphone specifications suffer at the hands of the Adpuff dept more than most!

Dave.
 
You will notice Freddies 'tash is brushing that mic grill? THAT is the 'room killer' aspect of such microphones. NOT the operating principle.

In fact I would bet the better, more expensive capacitor mics have a tighter and cleaner rear rejection factor than many dynamics. Trouble is, without independent acoustic test curves you could never tell. Microphone specifications suffer at the hands of the Adpuff dept more than most!

Dave.


Absolute truth. This is one of my personal reasons for using a higher grade mic. The null and rear rejection are almost always MUCH better than the cheaper more budget conscious mics. Another part of this equation is the frequencies being captured off-axis. Unless you are in a totally controlled environment, these frequencies ARE present. I have found this to be one of the good benefits of the reflection type guards. They do not keep out sound from the rear but they tend to have some control over frequencies you might not want hitting the mic from the rear in a lively room. Pair this with mics with tighter control over spill and bleed and you have a decent chance of a good capture on a vocal in a lot of less than desired situations.
 
I wonder if a foam ball doesnt do the same thing.
Foam balls can reduce plosives, wind background noise and help the single diagphrams back side issues.

Im not knocking the Reflexion thing, it does look professional and would do something to the mic area pickup but is it a huge improvement from just putting on a foam ball or tiewrapping a foam piece on there?

Its like p-poppers you can make a wire clothes hanger with material or buy a real one. Performance wise its the same, cosmetically not the same.

Maybe a piece of decent foam wrapped in the same general shape would work OK, but it will not do the same exact job. The contours and structure of the foam matter. Thicker foam would probably be required to do a similar job with less specific engineering. A windscreen is designed for an entirely different purpose though and would probably not help at all.

I am using polyethylene fiber for the acoustic absorption in my small home theater (bed pillows, sofa cushions, duvets) to avoid tracking fiberglass in and breathing it. This is my living room and I do not want silica floating in the air. Polyethylene fiber works fine AFAIK. The acoustics improved dramatically once I got the hang of it. I just had to be careful to keep the absorption close to the walls so that it stays out of the path of the ambient reflections bouncing around the small room, or it sounds dead. My bass traps are large cubic cardboard boxes stuffed with bed pillows and screwed into the ceiling tricorners or placed on the floor tricorners. Sounds and measures OK, as long as the bass traps are only in the tricorners, otherwise they intercept too much reflected ambiance and deaden the sound.

DIY definitely works, but it has to be appropriate tech. The materials and the construction need to take advantage of the physics if they are to do the job properly.
 
I have a mic shield issue, but it is a live sound situation, not a home studio.

I am noob/amateur at this audio thing. My expertise is electronics, not recording.

I mix live sound for East Crescent. The drummer provides the PA and most of the amps, including two small guitar amps with acrylic shield in front of each one to isolate the microphone. He generally places the amps next to each other on the floor, with the microphones close to the speakers and the shields somewhat farther away.

I think he maybe has this shield split in two pieces, one for each amp:

Control Acoustics VDS2X4 Combo Amp Sound Barrier Shield | Musician's Friend

I noticed at the latest gig (my first outdoor gig) with this band, the treble on the guitars was dramatically brighter and I had to cut back the treble considerably from what we used at the last indoor gig. Here is the YouTube playlist for that outdoor gig:

YouTube

I suspect that more woofer in the guitar amp might help the bass some outdoors, but hauling larger equipment is probably not an option.

Would a different microphone improve the tonality when mixing outdoors? I think it is an SM58 hanging by its cord in front of the woofer, slightly off center, or maybe on a low tripod stand. I cannot remember. Knowing Charlie it is probably on a stand.

What about a different sort of shield? Thin rigid materials only reflect down to about 500Hz. That means plexiglass behind a microphone behaves as a high pass reflector bouncing treble back into the microphone?

How about this?

The ONLY one I've found that works is this one: Halo - Aston Microphones
I've used it on location with several different mics in some lousy acoustical situations and it works quite well.
Studio In The Woods - Recording studio in Evart MI - BandMix.com

Would that help? If the shield is absorptive rather than reflective, would that help limit the tonal shift by avoiding treble reflection back into the microphone?

Could similar performance be achieved by lining the existing plexi shields with thick foam of appropriate composition?

Should the guitarists be cutting back their treble on stage for outdoor gigs?

Here are the 'indoor' and 'outdoor' EQ curves that I used on the lead guitar (his treble was painfully bright outdoors, with the 'indoor' EQ):

IMG_0289.PNG
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Should I have cut more treble in the PA? Where do we focus attention on this issue?

Here is a playlist demonstrating the 'indoor EQ':

East Crescent and Redwood Roots at O'Malley's Sports Pub 2017-02-03 - YouTube

I suspect that boundary reinforcement indoors from the wall behind the stage boosted the bass going into those microphones.

They had a substitute lead guitarist for that indoor gig who used far less treble on his guitar, but they had the same rhythm guitarist for both gigs. I use similar EQ on both guitars, with a slightly taller and narrower peak on the rhythm for a sharper Reggae chop and a slightly broader and lower peak on the lead for more melodic intelligibility over a broader frequency range.

The indoor sound is dramatically different, and far less bright even for the rhythm guitar, even with more treble boost in the PA. I am unsure how to compensate or even gauge the success of any compensation for outdoors, but I think some adjustment is in order somewhere.

Sorry if I am unintentionally hijacking the thread. I thought it was fair game given the open-ended nature of the OP's question. Thanks in advance for your helpful responses.
 
MY first thought was, "Bit rich, a DRUMMER putting acoustic shields around (small?) guitar amps!" (I COULD have said "Buddy Rich" but the Mods might chuck me off!) . Why? Most drummers I have heard should themselves be encased in 300mm of airtight acrylic! (last time I heard a band in our Labour club the balance was JUST right 2 walls away in the gent's bog!)

I cannot help you with your problem but the drummer sounds like a self aggrandizing nut to me.

Dave.
 
we all know the low sensitivity mics help remove the room. Think of the SM7 how its tucked inside the large body and has the perforated metal shield with usually foam over the shield, and sometimes the second foam piece on top of the thinner foam piece. includes holder...and filter switching.... $289used.

then it seems to me, if tossing blankets up on the walls, pillows, or even traps and foam and diffusers would be a larger project but allowing better results for about everything you track. Big fat pillows and duvet's and blankets, drapes, are noticeable...bass traps and professionally done bedrooms or basements even better.

??? the Reflexion/Filter/Shield devices $60 to $300. some noise rejection of the room? maybe more room dependent, certain applications of space or distance or setup? Im still not getting the targeted audience over a DIY thing. I saw a few commercial used Reflexions on craigslist at $50 - $40... I still

I notice all of the store bought "filters" on Google shopping are about the same distance from the mics. Does anyone know why they chose this distance? Is there some reason 12" away is better than 1" away vs 1 meter away?

I took a large foam-Aurelex type piece and held it up to my mouth as I spoke. then I moved it further away. My ears cant hear much but I suppose it could be the microphone specifically that might benefit more than my ears.
I dont know?
 

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MY first thought was, "Bit rich, a DRUMMER putting acoustic shields around (small?) guitar amps!" (I COULD have said "Buddy Rich" but the Mods might chuck me off!) . Why? Most drummers I have heard should themselves be encased in 300mm of airtight acrylic! (last time I heard a band in our Labour club the balance was JUST right 2 walls away in the gent's bog!)

I cannot help you with your problem but the drummer sounds like a self aggrandizing nut to me.

Dave.

If I gave anyone that impression, it was completely unintentional.
 
we all know the low sensitivity mics help remove the room.

Total noob here (just about) has no idea why or how? Sensitivity is a linear thing. A less sensitive mic may be better for high SPL? but probably does nothing at all about room acoustics. What you described is a shielded/damped mic and that is different?

I notice all of the store bought "filters" on Google shopping are about the same distance from the mics. Does anyone know why they chose this distance? Is there some reason 12" away is better than 1" away vs 1 meter away?

I took a large foam-Aurelex type piece and held it up to my mouth as I spoke. then I moved it further away. My ears cant hear much but I suppose it could be the microphone specifically that might benefit more than my ears.
I dont know?

I can make a few guesses.

Most acoustic sources are somewhat omnidirectional. Ominidirectional sources radiate sound in all directions according to the inverse square law. The sound energy is more dense close to the source, so any absorption placed close to the source absorbs more of the energy and that means it can be smaller while still absorbing the same amount of energy that a larger absorber would. 12" is just far enough away to avoid physical interference with the singer/instrument/whatever but still close enough to keep the size of the absorber manageable/affordable.

Another potential issue is that having lots of absorption in large semi-spherical structures could suck out room ambiance by getting in its way. The idea is to keep the sound source from contaminating the room, not to keep the room from contaminating the source.

But like I said, total noob here. I could be completely wrong.
 
One other thing, sound diffracts around obstables, including even the human voice as it leaves the human head, or so I saw in a video once where a woman twirls in an anechoic chamber and the low level of her voice that is audible from behind her is attributed to diffraction more than to her mouth being an omnidirectional sound source.

To work well with sound sources that are directional and about the size of a human head, presumably the shield has to be somewhat larger than a human head in order to intercept the majority of the sound being radiated somewhat directionally and diffracting around the head toward an omnidirectional pattern.

If the source were truly omnidirectional it would be a point source and the shield could be arbitrarily small as long as it has the requisite thickness. For a larger source emanating from a diffracting body, the sound would sort of 'crawl' around the surface of the body toward the rear, so the actual source radiates in a more diffuse pattern off a larger surface and the shield needs to be large enough to catch some of the spill off the sides/top/bottom of the body. An arbitrarily small shield would completely miss that diffracted energy and let it into the room.

Again, this is just speculation, but the physics would seem to back my supposition.
 
If I gave anyone that impression, it was completely unintentional.

Please accept my apologies CherylJosie, I did not mean to make fun of your problem. In my defence! It IS very uncommon for the drummer to be the offended party in a volume war! I base this conclusion on many years of reading of band issues on forums and some, years ago, experience.

Now. I commend your conclusion about microphone sensitivity and 'room rejection' from first principles. A scientific and reasoned approach to sound matters is rare in forums. You are perfectly correct. There is no magic about dynamic microphones or low sensitivity microphones (though the two are almost always one and the same) . The factor here is 'critical distance'. A low sensitivity mic has to be used very close to the sound source and thus the ratio of direct to ambient sound is very high. If you tried to use a mic of high sensitivity that close, something, the pre amp or the mic's impedance converter in the case of a capacitor, would overload and sound dreadful.

Sound, acoustics is a very slippery subject and one I only have the most tenuous, layman's grip on. One thing missing from your exposition is the fact that pressure gradient mics, i.e. anything that is directional, respond differently to Spherical wavefronts than they do to Plane wavefronts. This is the mechanics behind the 'Proximity Effect'.

The 'pop' filter is really there to reduce the effect of plosives, 'P's and can take the form of foam, cloth or a metal grill. I am not sure how they work but assume the material dissipates the 'pop' energy before it hits the diaphragm? They also of course keep out spit.

Dave.
 
Please accept my apologies CherylJosie, I did not mean to make fun of your problem. In my defence! It IS very uncommon for the drummer to be the offended party in a volume war! I base this conclusion on many years of reading of band issues on forums and some, years ago, experience.

I know what you mean. I jammed with a drummer who broke a stick at every practice and gave me two day tinnitus. They replaced me with someone who complained less.

The visual impact of Charlie's massive PA and lights in small bars is amusing, but the sound is excellent without being deafening. It helps to have a capable PA, but even more important is having a band with members that are strong enough to load it! Then it is a must for the band to be open to helpful suggestions and motivated enough to actually give them a fair trial.

Charlie has great dynamic control, and keeps a steady volume throughout a gig, plus he throws great parties with multiple bands entertaining his guests. He provides and transports a majority of the equipment for East Crescent, plus he personally plans the stage layout for every gig that his booking agent lines up. Some of the gigs involve literally dozens of guest performers and some of the gigs do not involve East Crescent at all but are entirely separate ventures.

Charlie carefully weighs my suggestions and gives them a fair trial despite my noob status even if it means making changes to the way he does things. The sound has improved dramatically since I first met him as a continuation of a long trajectory he was already on prior to my involvement, and everyone is happy about it. This guy is the real deal.

Five years ago he was half my age. It is humbling to see what he has accomplished in his spare time. I wonder what would happen if he had the funding and contacts to make music production his profession.

Now. I commend your conclusion about microphone sensitivity and 'room rejection' from first principles. A scientific and reasoned approach to sound matters is rare in forums. You are perfectly correct. There is no magic about dynamic microphones or low sensitivity microphones (though the two are almost always one and the same) . The factor here is 'critical distance'. A low sensitivity mic has to be used very close to the sound source and thus the ratio of direct to ambient sound is very high. If you tried to use a mic of high sensitivity that close, something, the pre amp or the mic's impedance converter in the case of a capacitor, would overload and sound dreadful.

OK, that makes sense. I have only ever owned a (third-hand) really old EV cardioid with very low sensitivity and the busted-out 'oops' switch, and some cheap Astatic mics I bought in the 1980s. My experience with microphones is basically nonexistent. All I did personally until recently is a little bit of home recording.

Sound, acoustics is a very slippery subject and one I only have the most tenuous, layman's grip on. One thing missing from your exposition is the fact that pressure gradient mics, i.e. anything that is directional, respond differently to Spherical wavefronts than they do to Plane wavefronts. This is the mechanics behind the 'Proximity Effect'.

Yes, total noob and not conversant with most of this. I read the Sure article about proximity effect, but did not understand much of it despite my engineering background. I get the conclusion just fine but the physics is something else.

This is my 'proximity EQ' that I use for vocals (I fine-tuned this at the most recent gig):

IMG_0283.PNG

I have another subgroup EQ for proximity effect on the drums but I have not spent much time on it. It looks like a flatter version of the vocals subgroup EQ.

The 'pop' filter is really there to reduce the effect of plosives, 'P's and can take the form of foam, cloth or a metal grill. I am not sure how they work but assume the material dissipates the 'pop' energy before it hits the diaphragm? They also of course keep out spit.

Dave.

There must be some fluid dynamics/areodynamics involved. Not conversant, but it seems that a plosive transient involves a prolonged rush that is sort-of momentary DC. My guess is that the material diffracts or channels much of that energy into tiny vortices that dissipate in tornado-like swirls within the material while also building back pressure from the resistance and deflecting a majority of the flow around the microphone. Maybe the physical characteristics of an absorber can be tailored to target velocity versus SPL in such a material. Again, all guesses on my part.

- Cheryl
 
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