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Vocal Booth - Strange phantom Plosives ???

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Vocal Booth - Strange phantom Plosives ???

Postby Matthew Seed » Mon May 10, 2021 3:37 pm

Hi guys & gals.

I have just bought a pro vocal booth by Kube its 1.2M X 1M (which is all I had room for in my recording studio) Its all built up great.

I have just put in there my TLM103 on a cradle, pop shield etc etc. All is good, then i did some test recordings on a female voice over.

I appear to be hearing on the P's what sounds like Plosives, so I checked the pop shield, the distance she was et etc and all is fine. If i blow hard on that pop shield I can't make a plosive sound. So I am a little perplexed.

I have not properly treated the inside yet with any foam etc. I do feel that there is a build up of low end in the air though, could it be some kind of standing wave or too much low end etc that is giving me this plosive type sound ?

What is the best way to treat a booth of this size, are bass traps needed ?

Thank you in advance
Matthew
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Re: Vocal Booth - Strange phantom Plosives ???

Postby blinddrew » Mon May 10, 2021 3:39 pm

Have you tried moving the mic around to a different position in the booth? It's where I'd start in the short term.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Kwackman » Mon May 10, 2021 3:44 pm

Also, try moving the mic off axis so it isn't pointing directly at the mouth. Above looking down is common.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Hugh Robjohns » Mon May 10, 2021 3:52 pm

Matthew Seed wrote:I appear to be hearing on the P's what sounds like Plosives...

It might help if we could hear what you're hearing, as you don't seem entirely convinced it is a plosives problem!

I have not properly treated the inside yet with any foam etc. I do feel that there is a build up of low end in the air though, could it be some kind of standing wave or too much low end etc that is giving me this plosive type sound ?

These kinds of booths are primarily intended to reduce external noise, and I'm not convinced the interior absorption is as well-balanced across all frequencies as it really should be -- which is perhaps not surprising given the size. Certainly all the compact booths I've heard tend to be poorly controlled at the low end, and adding foam will probably just upset the balance even further.

If you have a problem with external noise I can see why you'd need something like this, but otherwise I'd personally always prefer to set up a 'duvet tent' in a large-ish bedroom as that generally sounds much better!

What is the best way to treat a booth of this size, are bass traps needed ?

At 1 x 1.2m, if you install any kind of bass trap worth the name you'll never get your VO artist inside it again!

So... back to the 'plosive' problem... If you're sure the pop-screen isn't too close to the capsule (which renders it ineffective as a pop screen), and that your VO artist isn't somehow talking around the screen, then I'd investigate the possibility of mechanical shocks through the mic support and/or its cable.

I'd also try placing the mic in different positions in case there is a standing wave issue in the booth. Again at just 1.2 x 1m it's going to be very difficult to achieve, but I'd advise keeping the mic as far away from the corners as you can! :lol:
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Luke W » Mon May 10, 2021 4:02 pm

Lots of good advice already, but I'd like to second this:

Kwackman wrote:Also, try moving the mic off axis so it isn't pointing directly at the mouth. Above looking down is common.

:thumbup:

I almost always prefer the sound I get from the "forehead height tilted down" approach.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Matthew Seed » Mon May 10, 2021 5:24 pm

Thank you all very much.

I have tried moving the mic around, but as Hugh pointed out.....there isn't a huge amount of scope for movement really. The reason for the booth is that we live on a road and there is a lot of road noise, kids, barking dogs etc. I have to say the booth is outstanding at keeping all this out.

I am positive its not your normal plosive as like i said i tired really hard to make it do one by blowing on the pop shield and not a sausage. In fact thats what started to make me think it could be a standing wave or some such issue as when I blow on the pop I don't actual make a sound and thats not doing it, but the moment my VO talks its there.....what threw a spanner in my understanding works was it was only doing it on the P's.

I have found online smaller bass traps, are these no use i guess ?

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Re: Vocal Booth - Strange phantom Plosives ???

Postby Hugh Robjohns » Mon May 10, 2021 5:44 pm

I think we need to hear it...
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Wonks » Mon May 10, 2021 6:04 pm

The internal dimensions will give you the main standing wave fundamental frequencies, with the height giving the lowest frequency standing wave. Assuming the standard 2.1m overall height, and 80mm thick walls/floor/ceiling, then you have internal dimensions of 1.94m x 0.84m x 1.04m, with standing wave fundamentals of roughly 88Hz,
204Hz and 164 Hz respectively. Though in that small a space, a person standing in there will disrupt those standing waves considerably.

If you analyse the ‘plosives’, do any low frequencies close to those values appear? You’d not normally get strong frequencies much below 200Hz from the average female voice, so they should be quite apparent.

The other thing to consider is that different people make different levels of plosives and at different frequencies. So whilst the pop filter may work well for you, it may be less effective for your VO artist.

You could always try two pop filters in line, rather than just one (and try different types e..g. foam and metal grille). I have read about this being done in studios for people who produce strong plosives.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Hugh Robjohns » Mon May 10, 2021 6:57 pm

If it really is plosives moving the mic up should cure it (the forehead level, aimed down approach, as mentioned earlier), as should switching to an omni polar pattern, or increasing the spacing between mouth, pop-screen and mic.

Not all pop-screens are equally effective, of course. I declined to review a commercially manufactured (metal mesh) pop-filter a while back because it was very clearly ineffective!

But Matthew doesn't seem convinced it really is plosive blasting, anyway, and I suspect it could be either a mechanical problem with the mic mount/cable, or a boomy resonance of the room. Again, moving the mic position and mounting arrangement could help.

If I'm using a shock mount I try to use a thin, flexible cable from stand to mic, to prevent vibrations travelling down the cable, and make sure the pop-screen mounting doesn't compromise the shock-mount.

But hearing the problem unwanted noises might give a better clue to identifying the cause and finding the solution.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby forumuser840717 » Mon May 10, 2021 8:29 pm

I may have missed where you already answered these but:

Does it only happen with that one particular VO artist?

Have you tried asking her, as an experiment, to raise or lower the pitch and/or speech volume of her voice and re-record a bit that shows the problem in her normal voice?

Or tried reading the same passages yourself (or with a different VO artist) in the same position in the booth and relative to the mic?

Have you checked whether other recordings by the same artist , set up similarly with respect to the mic but outside the booth, exhibit any similar artifacts which may have been masked by environmental noise that's lowered by being in the booth?

Have you looked at a spectrogram against time to see what frequencies are happening and, particularly, when?
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Matthew Seed » Mon May 10, 2021 8:39 pm

Thanks Wonks & Hugh. I am going to do a little bit more experimenting now. I have tried 3 different pop shields (one of which was a metal mesh one hmmmm) One thing that you guys have flagged up is that I do have the pop clamped to the same stand as the mic, could be energy traveling down the metal stand. That said the TLM103 is in it's proper shock mount.

I shall report back.

Thanks all for your help.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Bob Bickerton » Mon May 10, 2021 9:35 pm

Nothing much to add but again shock mounts as well as pop filters vary in quality. If the source of the problem is one of those I’d highly recommend the Rycote USM systems https://mymic.rycote.com/devices/tlm-103/. It’s the best I’ve come across and certainly gives you peace of mind in most set-ups.

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Re: Vocal Booth - Strange phantom Plosives ???

Postby Exalted Wombat » Mon May 10, 2021 10:29 pm

You've decided to record vocals inside a wardrobe. Why? The acoustics inside a wardrobe are generally terrible.
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Re: Vocal Booth - Strange phantom Plosives ???

Postby Hugh Robjohns » Mon May 10, 2021 10:32 pm

Exalted Wombat wrote:You've decided to record vocals inside a wardrobe. Why?
Matthew Seed wrote:The reason for the booth is that we live on a road and there is a lot of road noise, kids, barking dogs etc. I have to say the booth is outstanding at keeping all this out
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Re: Vocal Booth - Strange phantom Plosives ???

Postby n o i s e f l e ur » Mon May 10, 2021 10:58 pm

Bob Bickerton wrote:Nothing much to add but again shock mounts as well as pop filters vary in quality. If the source of the problem is one of those I’d highly recommend the Rycote USM systems https://mymic.rycote.com/devices/tlm-103/. It’s the best I’ve come across and certainly gives you peace of mind in most set-ups.

Bob

Those are probably very good Bob, but I couldn't figure out how to install my rackmount gear into one so decided not to go with your previous recommendation of same. ;)
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