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Omnidirection microphone for session

21 Jan 07 - 07:12 AM (#1943130)
Subject: Omnidirection microphone for session
From: alison

I am wanting a microphone that will pick up all the players in an Irish session without specifically mic-ing anyone up, or plugging them in.

has anyone got any experience with using the sort of omnidirectional mic that sits in the centre of a table, or the ones that dangle over your head?

what works? what doesn't? any brands better than others?

are there any which can automatically turn down the banjos when a harp is playing? (just kidding all you banjo players) - but seriously - is that a problem for any of you that have used them eg the louder instruments drown out the quieter ones?

thanks

slainte

alison

Has anyone


21 Jan 07 - 07:21 AM (#1943135)
Subject: RE: Omnidirection microphone for session
From: Alec

Our handsfree phone uses an omnidirectional mic Alison.
I have to say it focuses more or less exclusively on the loudest sound at any given moment. Maybe a larger type might circumvent this problem though.


21 Jan 07 - 07:29 AM (#1943139)
Subject: RE: Omnidirection microphone for session
From: GUEST,Ray

You don't say exactly what you want the mic for. If its for recording, any decent omni should work - but I don't think decent ones will necessarily come cheap - there isn't so much of a market for them as cardioids. If its for PA/amplification purposes, you should probably forget it; people in the session will be too far away from the mic to be picked up sufficiently to be amplified adequately.

As to picking upsome instruments more than others, its called dynamic balancing. Used it in a BBC studio years ago when all but one of the mics had been taken to an outside bradcast. Have the banjo player sit further away - possibly in the pub down the road - and issue all the bodhran players with Stanley knives as beaters!


21 Jan 07 - 07:32 AM (#1943141)
Subject: RE: Omnidirection microphone for session
From: Leadfingers

Alison - Is this for recording , or sound augmentation ? Either way, what I have done is suspend microphones OVER the playing area , ponting down at the performers . My gear is all UniDirectional , so I have used three or four mics to cover the whole area .
No doubt some one will have a good idea for an Omni - Maybe one of those Flat ones on the ceiling ?


21 Jan 07 - 07:39 AM (#1943146)
Subject: RE: Omnidirection microphone for session
From: GUEST, Tom Bliss

Try a pressure zone mic - a flat plate that lies flat on the table. It'll give you the best sound.

Not too expensive - try this for £40

Audio-Technica

Tandy used to do an even cheaper one which was actually pro quality but you may have trouble finding on now.

Google or ebay or a PZM or boundary mic


But keep the table clear of beer bows rosin crisps and fipples


21 Jan 07 - 07:55 AM (#1943157)
Subject: RE: Omnidirection microphone for session
From: Bernard

Just what I would have said, Tom (See you at the Open Door Extravaganza on March 25th)! The Tandy one was actually a Crown PZM manufactured to a price exclusively for Tandy. If anyone wants it, I have a drawing for balancing and phantom...

PZM is Crown's trademark, BTW. The correct generic name for such a microphone is 'boundary layer', often nicknamed 'plate mic'.

Miking from above is good for some instruments (fiddles and wind), but not as good for others (reeds and fretted instruments). However, this can work to your advantage!

The hands-free phone 'focussing on the loudest sounds' isn't a feature of the microphone, it's because of a device called a 'compressor'. The device (in simple terms!) merely drops the overall volume when it 'hears' a loud sound to even things out - essential for a hands-free phone, etc. Okay, it's also there to eliminate feedback (before someone shouts at me!).

As Ray said, 'dynamic balancing' is the essence of a live recording. A well-rehearsed band would normally be properly balanced, but you don't have that luxury in a session - particularly with the 'prima donna' types who want to drown everyone else out... miaoww!


21 Jan 07 - 09:48 PM (#1943789)
Subject: RE: Omnidirection microphone for session
From: alison

thanks everyone, it is for amplification rather than recording.

i'm off to google Crown PZM

slainte

alison


22 Jan 07 - 07:03 AM (#1944089)
Subject: RE: Omnidirection microphone for session
From: Bernard

If you're using it for 'amplification', please bear in mind this is a 'Sound Reinforcement' application, as the microphone can also 'hear' the loudspeakers.

You'll have to go for a compromise on sound level - it won't be as loud as individually miking the instruments and using an audio mixer for balance, but will give the overall sound a 'lift'.

Ideally you need an amplifier (mixer-amplifier or separates) with a graphic EQ, or a 'sweep mid' EQ on the mic channel you are using, also known as a 'parametric' or 'paragraphic' EQ. This will enable you to filter out the prominent feedback frequency (frequencies).

You should not try to EQ things too much, as it will sound unnatural - but careful EQ settings will give you more sound level.

MAKE SURE that the microphone is as far away from the front of the speakers as is possible - behind them if you can.

It's preferable to use more speakers at lower sound level ('Low Level Distribution') than trying to do it all, say, with a combo amplifier (one like guitarists use with the amp and speaker in the same cabinet).

PM me if you need guidance on specifics - it's me day job!


22 Jan 07 - 07:14 AM (#1944096)
Subject: RE: Omnidirection microphone for session
From: alison

thank you very much Bernard.

that sounds like what I'm after, just something to boost it so that it is slightly louder than acoustic so it can get above the normal pub background noise

slainte

alison


22 Jan 07 - 07:27 AM (#1944102)
Subject: RE: Omnidirection microphone for session
From: Bernard

It will do exactly that!

;o)


22 Jan 07 - 09:47 AM (#1944234)
Subject: RE: Omnidirection microphone for session
From: GUEST,Laz

You need a stage boundary mic.
Somthing like a Shure EZB-C Stage Boundary Mic.


22 Jan 07 - 12:06 PM (#1944393)
Subject: RE: Omnidirection microphone for session
From: Mo the caller

For who's benefit are you amplifying? If people want to hear they'll shut up and listen, if not then the louder the amplification the louder they'll talk and....


22 Jan 07 - 02:23 PM (#1944560)
Subject: RE: Omnidirection microphone for session
From: Bernard

I think the problem is possibly ambient noise. Whilst I agree with you, Mo, there is also the inverse situation - people talk louder because they cannot hear!!

It is possible that those who want to hear cannot silence those who do not... a situation I sometimes find myself in.

I'm a solo performer who preferes to work without a sound system. I work with sound systems all day, y'see...

There is a masonic hall I frequently play gigs in. Sometimes the people all want to listen, and I don't have a problem. Occasionally there are people who are simply there for a night out, and really would prefer I didn't interrupt their conversations! Whilst a full PA system would drown them out, I'm more inclined to raise the level a little to keep everyone happy.

It's a compromise.


22 Jan 07 - 07:12 PM (#1944902)
Subject: RE: Omnidirection microphone for session
From: The Fooles Troupe

I once saw an interesting mic. At an accordion festival, many old timers were either leery of being near the mic, or 'hogged' it. Both attitudes made the sound tech guys job difficult.

At the front of the stage was a construction of perspex, with seemed like some 'boundary layer mounted' mic elements. The box was under a metre high, about 2-3 hand-spans deep and about a metre or so wide. the side were angled out wards to reflect sound into and towards the centre of the box. Many players were not even aware that this gadget WAS a mic...


22 Jan 07 - 10:13 PM (#1945045)
Subject: RE: Omnidirection microphone for session
From: GUEST,alison

yes its just to cut through the ambient noise.

we do another session which is mic-ed. I just want to try this for something different

I remember when I was in Doolin they had a tiny mic hanging about 3 feet over the musos heads. Any idea what that would have been?

thanks

slainte

alison


23 Jan 07 - 06:43 AM (#1945279)
Subject: RE: Omnidirection microphone for session
From: The Fooles Troupe

CIA


23 Jan 07 - 09:32 AM (#1945417)
Subject: RE: Omnidirection microphone for session
From: GUEST,Johnmc

I wonder if anyone could advise me on this issue (Bernard, please):
how does one set the individual volumes for each channel against the master volume,
particularly to minimize feedback?


23 Jan 07 - 11:04 AM (#1945531)
Subject: RE: Omnidirection microphone for session
From: Bernard

It's a complex issue. I'll try to make it simple... -ish!

The Master Volume should not be set too high, to avoid 'pre-amp noise'. This is often a compromise, depending on the quality of the equipment.

Let's start at the beginning (cue for a song?!)...

A 'serious' mixer or mixer-amp will have separate controls on each input channel for EQ and Input Gain.

Input Gain is not to be confused with 'Volume' - this is the control which sets how much signal is accepted into the channel, and it set too high will cause signal distortion even at low levels.

Usually the Input Gain has a 'clipping' LED nearby - this ought not to illuminate except for the occasional flash if someone shouts down the microphone. If it is constantly lit, turn the input gain down gradually. Setting it too low, however, is nearly as bad, as you will amplify the pre-amp noise!

Okay, assuming each channel gain is now set, open the Master Volume to around -15dB as a rough guide. If you haven't got 'negative dB markers', between halfway and threequarters is near enough.

Now open one vocal mic channel gradually until you hear it start to 'ring'. A small ajdustment of the EQ at the frequency of the feedback should enable you to find a little more level from that microphone before it squeals. You should be wary of doing too much to the EQ of a mic, or it will sound unnatural - again, 'compromise' is the keyword.

'Squeak out' each microphone in the same way independently, and then gradually open them all together.

You will find the feedback occurs at a lower level, now... nothing is actually wrong, it's a function of having more microphones 'open'. If you have one microphone open to 'ringing point', you may find you have to back it off by about -3dB when you open another. It's done by feel - listen for the 'ringing', and move the controls very gently by small amounts.

I haven't mentioned any amplified instruments yet. The mistake most people make is to balance out the instruments and try to make the microphones shout above them. WRONG! Get your microphones right, then gradually balance the instruments underneath! This is because there is a limit on how much level a microphone will deliver before it feeds back; such a limit isn't always imposed by instruments... unless they use microphones, of course (Instruments with microphones need to be dealt with in a similar way to vocal mics).

Another useful hint... add your effects (reverb, chorus, etc) after you've got the balance right - then you will know what is causing the unexpected feedback!

This isn't something that works too well on paper, so you will have to experiment based upon the hints to find a good balance.

The Master Volume can now be used to slightly raise or lower the overall balanced signal if need be.

Vocal microphones such as the Shure SM58 are designed specifically for close vocal work - your lips should be virtually touching the gauze ball. If you back off a little, it will 'pop' quite seriously on explosive consonants (p and b). Working around 2" (50cm) away as many people seem to do is precisely why they pop!

Again, on paper it's not easy - experiment!

Microphone technique is just as important as correct setup. I usually tell people to imagine they have their tongue glued to the end of the microphone... keep your mouth pointing at the mic even though you are turning your head, say, to look at the guitar neck.

Does this help?


23 Jan 07 - 11:42 AM (#1945565)
Subject: RE: Omnidirection microphone for session
From: GUEST,Johnmc

I am very grateful for these guidelines. Thanks for taking the time. So clearly put, even I could follow it.


23 Jan 07 - 11:56 AM (#1945587)
Subject: RE: Omnidirection microphone for session
From: Bernard

That's funny - I don't understand a word of it!!

;o)

Seriously, though, I hope you are able to make use of it.


24 Jan 07 - 05:21 AM (#1946374)
Subject: RE: Omnidirection microphone for session
From: Mo the caller

Thanks Bernard,I've got that saved (though its easier to hand my mike receiver to someone in the band and ask them where they want to put it)

Having sat in the front row at Northwich, I'm surprised you ever need PA.


24 Jan 07 - 11:50 AM (#1946682)
Subject: RE: Omnidirection microphone for session
From: Bernard

Hah! Now I know who you are!!

At least you don't need your ears syringing then!!

Working with sound systems is me day job, Mo... I prefer to sing without - and now you know why!!

;o)