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Author Topic: acoustic guitar feedbacking through PA  (Read 3084 times)

carne_de_res

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acoustic guitar feedbacking through PA
« on: August 06, 2006, 12:36:17 pm »

i own a small PA (250 w) and have problems micing my acoustic guitar (it doesn't have a jack output) without nasty feedback.

i tried different condenser mics (451, 441, Rode Nt1) and i cannot have a decent level without having the guitar feedback.

no matter how close i put the mic to the body, no matter the mic angle and position. no matter the eq on the guitar channel and master output.

i tried a different guitar with a DI box and the increase in volume was noticeable. a strong signal with no feedback (after all the PA can be pretty loud, i've used it on several rock shows with a good amount of volume).

but i'm not enthusiastic about the way a DI'ed guitar sounds, if you know what i mean.

i have a show next Saturday and i'm desperate for some advice.
what do i do?

thanks in advance for your precious help.
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Joe Black

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Re: acoustic guitar feedbacking through PA
« Reply #1 on: August 06, 2006, 04:27:37 pm »

carne_de_res wrote on Sun, 06 August 2006 12:36

i own a small PA (250 w) and have problems micing my acoustic guitar (it doesn't have a jack output) without nasty feedback.

i tried different condenser mics (451, 441, Rode Nt1) and i cannot have a decent level without having the guitar feedback.

no matter how close i put the mic to the body, no matter the mic angle and position. no matter the eq on the guitar channel and master output.

i tried a different guitar with a DI box and the increase in volume was noticeable. a strong signal with no feedback (after all the PA can be pretty loud, i've used it on several rock shows with a good amount of volume).

but i'm not enthusiastic about the way a DI'ed guitar sounds, if you know what i mean.

i have a show next Saturday and i'm desperate for some advice.
what do i do?

thanks in advance for your precious help.



You could try a hypercardoid dynamic shoved right up to the guitar, but having played in a string band for many years and run sound for a few more, if you don't have a room that is condusive to mic'ing up the instruments (large stage, a decent room with high ceilings and good sound engineer) you go without monitors or put a pick up on your guitar.
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Andy Peters

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Re: acoustic guitar feedbacking through PA
« Reply #2 on: August 06, 2006, 06:03:43 pm »

carne_de_res wrote on Sun, 06 August 2006 09:36

i own a small PA (250 w) and have problems micing my acoustic guitar (it doesn't have a jack output) without nasty feedback.

i tried different condenser mics (451, 441, Rode Nt1) and i cannot have a decent level without having the guitar feedback.

no matter how close i put the mic to the body, no matter the mic angle and position. no matter the eq on the guitar channel and master output.


Face it, getting adequate volume in both the house and the monitors with a mic on an acoustic guitar is difficult.  The best you can hope for is if you use a hypercardioid or one of those small mics that mount inside the body.

Quote:

i tried a different guitar with a DI box and the increase in volume was noticeable. a strong signal with no feedback (after all the PA can be pretty loud, i've used it on several rock shows with a good amount of volume).

but i'm not enthusiastic about the way a DI'ed guitar sounds, if you know what i mean.


Then you're using the wrong pickup/preamp combination.  A simple bridge-mount piezo through a passive DI won't work; the DI will load down the pickup too much.  You need, at the least, a good active DI, like a Countryman or a Radial or a BSS (and NOT the Behringer clone of the BSS).  Less loading means better HF response, among other things.

The LR Baggs stuff works quite well.  The Sundown preamps are impressive.

Be prepared to spend some money.

-a
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carne_de_res

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Re: acoustic guitar feedbacking through PA
« Reply #3 on: August 08, 2006, 05:02:21 am »

[/quote]
The best you can hope for is if you use a hypercardioid or one of those small mics that mount inside the body.
[/quote]

please, tell me more about those small mics that you can put inside the guiar.
any suggestions about models?

thanks again.
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Joe Black

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Re: acoustic guitar feedbacking through PA
« Reply #4 on: August 08, 2006, 08:26:46 am »

carne_de_res wrote on Tue, 08 August 2006 05:02



The best you can hope for is if you use a hypercardioid or one of those small mics that mount inside the body.
[/quote]

please, tell me more about those small mics that you can put inside the guiar.
any suggestions about models?

thanks again.
[/quote]

I have a astereo set up in one of my guitars - Highlander IP2; saddle piezo and a small mic
http://shorelinemusic.com/amplification/highlander_mic.shtml . AKG and Crown make small condensors also.
Again, works great on a large stage with a competent sound man and monitor system. However, to get a good sound from the mic, it has to point at the strings and therefore the sound hole and out into the room. I can guarantee that if you use monitors in a small room, you will feed back through a mic like this. In fact I would almost gurantee that in a small room with lots of hard, reflective surfaces, you will feed back from the mains also. I've not met anyone whose ever used a internal mic system on it's own, they've always blended it with a piezo or a tranducer of some kind.

Your best bet is to get a decent piezo saddle pickup or trandcuer installed by a competent luthier. I used highlanders in both my live guitar rigs, both are stereo, one set up wiht the mic, the other set up with a Sunrise. I lke the Sunrise, but don't really like to have to take it in and out of the sound hole (this is after 15 years of using it) so that guitar pretty much used for large band arrangements where a true "acoustic" sound is really  not necessary. Does it sound like my guitar through a mic. No. However through a good sound system, it sounds good.


Other pickups that I've heard in guitars that sounded good and played by people I did sound for are LR Baggs I Beam and B Band.
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Andy Peters

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Re: acoustic guitar feedbacking through PA
« Reply #5 on: August 08, 2006, 02:54:03 pm »

carne_de_res wrote on Tue, 08 August 2006 02:02

Quote:


The best you can hope for is if you use a hypercardioid or one of those small mics that mount inside the body.



please, tell me more about those small mics that you can put inside the guiar.
any suggestions about models?


DPA.  Be prepared to open your wallet.

http://www.dpamicrophones.com/Images/DM00737.jpg

I agree with Jeff Roberson ... you'll want a pickup as well.

A common approach is to use just the pickup in the monitors and a blend of pickup and microphone in the FOH mix.

-a
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Joe Black

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Re: acoustic guitar feedbacking through PA
« Reply #6 on: August 08, 2006, 05:14:29 pm »

Ah HA! I beleive that DPA is the one Mithc Corbin, David Brombergs gutiarist was raving about when we played together a few months ago - he had it and the Baggs I-Beam wired together in stereo, I Beam in the monitors only, blended in the house. Sounded fantastic!
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Klokkern

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Re: acoustic guitar feedbacking through PA
« Reply #7 on: August 09, 2006, 03:50:40 am »

I would forget using a microphone if I were you. You will always have a feedback problem or the sound will get muddy or strange if you put it inside the guitar.

A good pick up system through a tube DI box (Get a Ridge Farm Gas Cooker/Manley/Demeter, forget the $100 dollar so called tube DI´s...) will give you great results! I prefer tube DI´s over the best active boxes (Klark Teknik/BSS/Countryman). But be prepared to pay for a good tube DI. They ARE expensive.

Regards,
larsK
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mattrussell

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Re: acoustic guitar feedbacking through PA
« Reply #8 on: August 09, 2006, 12:44:08 pm »

in the context of trying to get the acoustic guitars loud and loud in a mix of a fairly loud band, i can share with you my experience.

having spent nearly ten years playing in a fairly loud live band that has an acoustic gtr player, i feel your pain.  in my band, the acoustic gtr is the basis for ALL of the songs and needs to be heard at all times.  the line up includes drums(me), electric bass, electric gtr, keys (b3 and string pads) and 3 vocals.  we play pretty loud and the acoustic has always been a problem until recently.

my brother is the acoustic gtr player.  he owns several $2500+ instruments and had been playing them with one of those fishman blend set-ups that has individual controls for the piezo and internal mic with a TRS 1/4" that can blend the sound or split it into two outputs.  he always split it.  at the mixer, he would have our FOH guy create a blend to use in the house and send only the peizo to the monitors.  it didn't really ever do the job all that well.

he recently did a bunch of research and talked to some notable national players and techs who all told him the same thing which is that if you are playing rock and trying make the instrument loud, you first need to play a cheaper and less "hi-fi" sounding gtr and second, you need commit to using only a piezo while using a soundhole cover.  

he did it. bought two guitars that seemed to be popular amongst pro's and it works incredibly well.  they cut through and feedback is gone.

here is what he uses live now:  

Takamine EAN40C
CT-4B Preamp (included)  
http://www.takamine.com/?fa=detail&mid=124&sid=62

the guitars by themselves sound pretty terrible. he's now exclusively using the piezo through a radial passive DI to the PA and it's not bad at all.  i asked him to buy that passive DI as many of the venues have phantom problems (yeah, none at all) and batteries die.  

i was tracking him at a studio recently using those gtrs, just cutting scratch tracks for me to play along with.  later, when  i listened to them i was surpised how good it sounded.  so good that if i HAD to make it work, i probably could.  i won't be doing that, but if i was handed them to mix with no possiblitly of re-cutting them, i could certainly make it work.

EDIT:  we do carry a countryman DI85 with us and use it when we can (battery not dead or board has working phantom).  the radial does sound just fine though.
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carne_de_res

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Re: acoustic guitar feedbacking through PA
« Reply #9 on: August 09, 2006, 01:53:58 pm »

mattrussell wrote on Wed, 09 August 2006 18:44

in the context of trying to get the acoustic guitars loud and loud in a mix of a fairly loud band, i can share with you my experience.

having spent nearly ten years playing in a fairly loud live band that has an acoustic gtr player, i feel your pain.  in my band, the acoustic gtr is the basis for ALL of the songs and needs to be heard at all times.  the line up includes drums(me), electric bass, electric gtr, keys (b3 and string pads) and 3 vocals.  we play pretty loud and the acoustic has always been a problem until recently.

my brother is the acoustic gtr player.  he owns several $2500+ instruments and had been playing them with one of those fishman blend set-ups that has individual controls for the piezo and internal mic with a TRS 1/4" that can blend the sound or split it into two outputs.  he always split it.  at the mixer, he would have our FOH guy create a blend to use in the house and send only the peizo to the monitors.  it didn't really ever do the job all that well.

he recently did a bunch of research and talked to some notable national players and techs who all told him the same thing which is that if you are playing rock and trying make the instrument loud, you first need to play a cheaper and less "hi-fi" sounding gtr and second, you need commit to using only a piezo while using a soundhole cover.  

he did it. bought two guitars that seemed to be popular amongst pro's and it works incredibly well.  they cut through and feedback is gone.

here is what he uses live now:  

Takamine EAN40C
CT-4B Preamp (included)  
http://www.takamine.com/?fa=detail&mid=124&sid=62

the guitars by themselves sound pretty terrible. he's now exclusively using the piezo through a radial passive DI to the PA and it's not bad at all.  i asked him to buy that passive DI as many of the venues have phantom problems (yeah, none at all) and batteries die.  

i was tracking him at a studio recently using those gtrs, just cutting scratch tracks for me to play along with.  later, when  i listened to them i was surpised how good it sounded.  so good that if i HAD to make it work, i probably could.  i won't be doing that, but if i was handed them to mix with no possiblitly of re-cutting them, i could certainly make it work.

EDIT:  we do carry a countryman DI85 with us and use it when we can (battery not dead or board has working phantom).  the radial does sound just fine though.



i should have added i'm playing solo.
it's only me, my guitar and the PA. feedback hell nonetheless.
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rodabod

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Re: acoustic guitar feedbacking through PA
« Reply #10 on: August 09, 2006, 03:21:07 pm »

I'd try a magnetic pickup if you don't like the piezo sound. I hate piezos.

I used a Fishman Rare Earth single-coil for a few years for playing live with my old band, and it was good.
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Roddy Bell

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Re: acoustic guitar feedbacking through PA
« Reply #11 on: August 14, 2006, 12:41:51 pm »

In my experience, when trying to mic an acoustic instrument on a stage to be amplified, the majority of what causes feedback is nasty off axis coloration of the microphone response.  The only microphone I've found to work well in this situation is an Earthworks SR69 cardioid microphone.  It's on and off axis response is very smooth.  

However my experience with this situation is limited, as in the past several years of running live sound I've ran into no more than 4 or 5 bands that didn't have pickups installed in their acoustic instruments.

You might get a better response over at the lab lounge over in the srforums section of the prosoundweb.


Goodluck

-Jeff
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carne_de_res

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Re: acoustic guitar feedbacking through PA
« Reply #12 on: August 15, 2006, 07:53:31 pm »

in the end i used two MD 421's placed on 12th fret and body of guitar.
i've risked feedback a couple of times during the performance but i had good overall level.

i am _very_ interested in the Earthworks mic you mentioned, Jeff.

thanks for all the feedback (pun intended), guys.
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Funk-O-Meter

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Re: acoustic guitar feedbacking through PA
« Reply #13 on: August 17, 2006, 03:00:58 am »

Nobody thought to ask him what kind of PA gear he was using?



To get a condenser mic hot enough to hear in a monitor on stage in a noisy room you'll need:

A good monitor- some thing like a Yorkville Elite or one of those powered Mackies at the minimum.

A graphic EQ- You're gonna really need a 1/3 octave (same as 31 band) EQ to pull out the offending frequencies.

The wisdom to know what bands to pull- The basic ringing out process is this:

1. Flaten the eq and bring the level up till its just about to 'take off' when you play.

2. Find what frequency that is and pull it down till it sounds safe. Thats the hard part determining what frequency it is. Not eaysy if your not good with your frequencies. Usually with acoustic guitars its in the low mids. 400-800hz.

3. Repeat 3 or 4 times till you've got all the most offensive frequencies pulled (about 6-12 db). If it takes more than that many your reaching the area of diminishing returns and it won't really get that much better.

Honestly that's why everybody goes with installed piezo or transducer pickups. They don't sound near as good but at least you can hear! Using a dynamic mic really close like as was suggested will help a good bit. I'd use a Shure 57.  There has yet to be a great solution for your problem except for maybe in ear monitors. Which completely do away with stage monitors all together. Thats what I wound up with.

No mater what micing or pickup method you wind up using the above method for using a graphic EQ will help you greatly.

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Andy Peters

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Re: acoustic guitar feedbacking through PA
« Reply #14 on: August 17, 2006, 02:38:09 pm »

Funk-O-Meter wrote on Thu, 17 August 2006 00:00

To get a condenser mic hot enough to hear in a monitor on stage in a noisy room you'll need:

A good monitor- some thing like a Yorkville Elite or one of those powered Mackies at the minimum.


BARE minimum.  And the powered Mackie isn't a good choice for monitor wedges because of its horn angle.

The Rat/Radian Microwedge is a much better choice.  Spendy, though.

Quote:

A graphic EQ- You're gonna really need a 1/3 octave (same as 31 band) EQ to pull out the offending frequencies.


A parametric inserted on the guitar channel is the pro's preferred tool.  Why?  So you don't destroy the tone of the wedge with the cuts you might end up with on a standard 31-bander.

Actually, the cool trick when you don't have a separate monitor desk is to split the channel.  Use one channel for FOH (perhaps inserting a compressor or whatever) and use the other channel for monitors.  Insert the parametric on the monitor channel if necessary.

(Of course, if your monitor console has decent channel-strip tone controls, you can do perhaps skip the inserted parametric, but I don't think our friend here is dealing with such consoles.)

re: ringing out wedges -- yes, very important, although a 12 dB cut is just plain wrong.  Don't forget that if you have both the vocal and the guitar in the wedge mix, you end up with two different path lengths and some odd potential feedback combinations.  I've seen guys simply hack the graph until there's nothing coming out of the wedges yet the send is clipping.  Splitting both vocal and guitar and using the channel strip for each works better than hacking the graph.

-a
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