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Author Topic: RE: Using a feedback destroyer on vocal mic inputs only.  (Read 1945 times)

Offline Sachiru

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RE: Using a feedback destroyer on vocal mic inputs only.
« on: December 27, 2011, 10:33:52 PM »
Good <insert appropriate time here> po sa lahat ng andito!

Magtatanong lang po sana ako kung pwedeng gawin itong naisip ko, and paano. Pagpasensiyahan nyo na po sana ako sa noobishness ko.

Meron po kasi kaming gagawing system for conference room and/or pa. Ang expected pong use niya is mainly speech, with the occasional (as in three 5min music tracks per 2 hour usage) music thrown in. Balak po sana namin eh as much as possible, idiot-proof po yung setup kasi hindi talaga professional audio engineers ang maghahandle ng operation ng sound equipment (volunteers with good intentions and not-so-good training).

After hearing the actual sound output po from feedback destroyers like the DSP1124 and the Driverack, napansin ko po na although it is awesome at reducing feedback, it is also awesome at killing the vibrance of music. Considering that we're using music rarely, this is not a problem, pero siyempre mas maganda if nasusupress po niya yung feedback sa speech mikes (as in speech talaga, no vocals for music), while keeping the entire spectrum po for music.

Ang naisip ko po sana is to use the bus/aux sends of the four speech microphones. Pagsasamasamahin ko po sila sa isang bus output, ipapadaan po sa feedback destroyer, then ibabalik sa mixer. The brand and model of the mixer would be either the Behringer 1202 or 1204 po.

Pwede po bang gawin yung naisip ko (group all speech mikes into one bus, send to feedback destroyer (DSP1124), then return it to mixer for mixing to main)? If so, paano po?

Maraming salamat sa mga magbabasa at tutulong!

Offline Sachiru

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #1 on: December 27, 2011, 10:46:36 PM »
Ask ko na din po sana if ever hindi behringer, ano pong kakasya sa 25k budget na power amp (at least 100W 8ohm per channel), mixer with at least 4 mic inputs and 2 aux inputs, and feedback destroyer or equalizer with feedback detection po na brand new equipment ang pwede.

Pasensiya na po kung medyo demanding. Volunteer lang po kasi kami lahat and very, very limited po ang budget. Pasensiya po ulit!

Offline KitC

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #2 on: December 28, 2011, 10:05:25 AM »
Proper mic placement and floor wedge postioning is probably the cheapest way of eliminating feedback. Remove ANY monitors from your backplane.
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Offline Sachiru

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #3 on: December 28, 2011, 10:34:27 AM »
Proper mic placement and floor wedge postioning is probably the cheapest way of eliminating feedback. Remove ANY monitors from your backplane.

Thanks po!
Regarding monitors, since essentially PA system po siya, wala po kaming on-stage monitors. Hindi po kami front-of-hall, indoor conference room po kasi siya and ang ginawa is multiple overhead speakers over the entire area po, except for the stage. Minsan nga lang po pag may Q&A sa audience, meron pong roaming microphones, and syempre po hindi maiiwasan na minsan po may magtatanong/sasagot na saktong nasa ilalim ng overhead speaker (tapos ang hina pa ng boses nya na hindi mo alam kung tataasan mo yung gain para marinig siya o hihinaan mo dahil may feedback na).

Anyway po, pwede po ba yung ganun na certain inputs lang po ang nakabus towards feedback destroyer, and hindi yung main mix?

Offline choco_bam

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #4 on: December 28, 2011, 12:03:05 PM »
i agree with kit c


Offline tjlimjoco

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #5 on: December 28, 2011, 03:58:41 PM »
Proper mic placement and floor wedge postioning is probably the cheapest way of eliminating feedback. Remove ANY monitors from your backplane.

Mism0  :)

Offline Sachiru

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #6 on: December 28, 2011, 04:48:41 PM »
As we said, wala po kaming monitors, and hindi ko naman po pwedeng sabihin dun sa audience na "kung magtatanong po kayo mamaya during the Q&A, pakisuyo po iwasan ninyong umupo sa ilalim ng ceiling-mounted mikes na nandyan po nakalagay sa halos lahat ng lugar po ng hall".

Offline mikep

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #7 on: December 28, 2011, 05:29:25 PM »
 Doing it SIMPLE is the best way to avoid problems such as feedback in PA situations.  There might be an over design of putting a lot of loudspeakers all over the room, with the aim of achieving good coverage.  This may result to more problems than solving good sound dispersion.  Is the sound system design based on a distributed system - meaning the loudspeakers are put in the ceiling feeding directly downward, imbedded in the ceiling, or do you have multiple speaker system all around the room placed on the top portion of the wall or in the ceiling, all aimed towards the audience?  The best way is to just use 1 or 2 speakers coming from front aimed towards the audience and keeping its SPL or volume within sensible levels.  How big is the room?  What type of speakers are used?  How many speakers?  Using feedback eliminators may help but normally they affect the sonic quality of the sound system as they try to automatically suppress possible feedback frequencies.  At the end of the day, you sound becomes either thinny or bassy, unintelligible, unnatural, bad sounding.  Better not to use these types of gadgetry and just make things simple.  Maybe it would help if you could post pictures for us to see the actual situation.   
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Offline Sachiru

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #8 on: December 28, 2011, 09:15:00 PM »
Doing it SIMPLE is the best way to avoid problems such as feedback in PA situations.  There might be an over design of putting a lot of loudspeakers all over the room, with the aim of achieving good coverage.  This may result to more problems than solving good sound dispersion.  Is the sound system design based on a distributed system - meaning the loudspeakers are put in the ceiling feeding directly downward, imbedded in the ceiling, or do you have multiple speaker system all around the room placed on the top portion of the wall or in the ceiling, all aimed towards the audience?  The best way is to just use 1 or 2 speakers coming from front aimed towards the audience and keeping its SPL or volume within sensible levels.  How big is the room?  What type of speakers are used?  How many speakers?  Using feedback eliminators may help but normally they affect the sonic quality of the sound system as they try to automatically suppress possible feedback frequencies.  At the end of the day, you sound becomes either thinny or bassy, unintelligible, unnatural, bad sounding.  Better not to use these types of gadgetry and just make things simple.  Maybe it would help if you could post pictures for us to see the actual situation.

Ay ganun po ba? Pasensiya na po.. Sige po, I'll try to get pix of the venue (fixed installation) para po may idea kayo. 128 sq m po yung room, acoustic tile ceiling, imbedded po sa ceiling directed directly downward po. Inabutan ko na po yung installation na ganun, nasira lang po yung dating sound system kaya po ask ko po ngayon what magandang gawin sa kaniya. Medyo distributed po yung system kasi 12 small speakers po siya, and wala pong FOH directed towards the audience kasi "nakakapangit ng stage"  :?

Try ko po magpost ng pics bukas.

Offline mikep

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #9 on: December 29, 2011, 01:53:56 AM »
In that case, keep your SPL low, just enough to be intelligible.  This is to avoid feedback.  Find for a setting which will be satisfy good understandable speech requirement as well good, natural sounding audio.  If you have a mixer, set your EQ flat, but with a bit of boost on about 8 to 10 kHZ. for intelligibility purposes.  Cut at 60 hZ.  Or engage on your high pass filter button, then lessen your low frequency, about 75 hZ. by another 3 dB.  That will hopefully give you better audio and less feedback problems.   
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Offline Sachiru

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #10 on: December 29, 2011, 11:04:05 PM »
As promised, here are pics of the venue:

Click Here for larger version.
Click Here for larger version.
Click Here for larger version.
Click Here for larger version.

The program usually consists of:

3mins opening song.
1 hour speeches.
3mins middle song.
1 hour speeches.
3mins concluding song.

Songs are usually piano arrangements, with vocals rarely done.
As you can see from the pix, the speakers are distributed over the hall area, and madalas po kaming may nakikitang attendee na napakamahiyain, tapos uupo sa ilalim ng speaker cone, kaya hirap pong magbalanse ng sound para dinig ng lahat, pero hindi nagfefeedback, na hopefully maayos po ng feedback destroyer.
« Last Edit: December 29, 2011, 11:08:11 PM by Sachiru »

Offline mikep

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Re: RE: Using a feedback destroyer on vocal mic inputs only.
« Reply #11 on: January 03, 2012, 05:52:55 PM »
Keep your SPL (volume) low.  Concentrate on speech frequencies.  Read my post before this.  If ever you would have budget, better to buy two active tyupe speakers, even 12 inchers only, placed on pole stands, left and right of the stage, along with the distributed system.  That will provide point source and good intelligibility.  Hope this helps.
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