Monitor feedback

[spinynorman]

We're using a Mackie SRM350 as an active monitor for vocals, but the singer often can't hear herself. It's 165W and the obvious solution is a more powerful monitor. But part of the problem is feedback when the monitor is turned up, despite spending a lot of time on EQ to cut it out. Although the Mackie is mainly an active PA speaker, Mackie claim it works well as a monitor and reduces microphone feedback.

My question is - if a good 165W monitor feeds back at a certain volume/eq level, will a more powerful monitor still feedback at the same level, or should it be able to go louder? Or could the problem be the level of the signal coming in?

Edited November 17, 2009 by spinynorman

[tombboy]

A monitor will only be as good as the singer, microphone, technique and the room it is used in.
A bad mic, bad mic technique and acoustics will seriously damage the monitor's performance.
If none of the above, then eq the hell out of it!

[Moo]

Which Microphone is she using? Cheaper mics often have nasty spikes in response that cause feedback.
A hyper cardoid may help, but some singers don't like them because they only pic up in a narrow area, and go quiet the instant they turn there head or back off a bit.

In your situation, a larger monitor will just cause louder feedback. The feedback is caused by the specific frequency reacing a level that the Microphone can 'hear.' Larger / Louder monitors will not change that level.
You can make the situation better by using mics with smoother freq response, Dito Monitors with smooth resonse (Sory but Not cheap plasic P.A. speakers)
Or buy putting a Graphic or feedback filter inline before the monitor.

You can gain 12db (four times louder) before feedback if you have a decent graphic eq on the monitor channel. It must be at least 16 band, but preferably 32 band to be usefull though.
Anything less than a 16 will have wide frequency bands, and will just cut out the frequencies that you need to hear yourself.
When you start cutting wide frequency bands (Which are often on P.A. Mixer amps) to combat feedback, you will tend to cut all of the high mids where the prescence boost of the mic is. The reason that precence band is engineered into the mic is to make the vocals come through the mix more clearly.
When you cut this on the graphic to stop feedback, suprise suprise the vocalist cannot hear themselves.

I set the monitor graphics on my P.A. system with an RTA (Real Time Analisys) program on my laptop. I have 20 years of (weekend warrior) experience as a sound engineer, and when I set one by ear, it is still only just in the ballpark compared to the RTA. A Properly set graphic should look completely random, with no smiley face etc. patterns.
Its not uncommon for singers to ask me to turn monitor levels down after I have set up the stage. I can hit the limiters on my 300w monitor amps with no feedback using the RTA.

Hope this helps.
Moo.

Edited November 17, 2009 by Moo

[velvetkevorkian]

Moo, is the RTA just so you can see exactly which freqs are peaking so you can cut them more precisely?

[spinynorman]

Ok, thanks so far. The mic is Shure SM58. I take it the cheap plastic speaker is the SRM350 - it felt quite expensive to me, but agreed it isn't primarily a monitor. Gear is a constant compromise between size, weight, cost and performance. Can you give me an example of a monitor with smooth response, since we've more or less decided to replace the Mackie with something else?

EQ may well be the answer, as there is limited EQ on the mixer. FOH is generally ok, the problem's always with the monitor.

[Bill Fitzmaurice]

[quote name='spinynorman' post='657403' date='Nov 17 2009, 02:37 PM']We're using a Mackie SRM350 as an active monitor for vocals, but the singer often can't hear herself.[/quote]
Only one? A monitor per player/singer is the norm, and EQ isn't an option, it's mandatory. If that's all in place and she still can't hear herself: turn the instruments down.

[maxrossell]

I notice you say "she". I don't want to jump to any conclusions, but is she a quite quiet singer?

The reason I ask is that a noise gate might be a solution, but that will only work if she has good projection (if she doesn't the gate will step all over her quieter vocals). You can pick up like a Boss NS-2 for a handful off change on the 'bay, and run it all the way up as an insert on the desk.

[LawrenceH]

[quote name='spinynorman' post='657626' date='Nov 17 2009, 11:13 PM']Ok, thanks so far. The mic is Shure SM58. I take it the cheap plastic speaker is the SRM350 - it felt quite expensive to me, but agreed it isn't primarily a monitor. Gear is a constant compromise between size, weight, cost and performance. Can you give me an example of a monitor with smooth response, since we've more or less decided to replace the Mackie with something else?

EQ may well be the answer, as there is limited EQ on the mixer. FOH is generally ok, the problem's always with the monitor.[/quote]

If it's feedback that's limiting your volume then you've not run out of monitor power. EQ is the way forward and cheaper than a new speaker that will probably need EQ to maximise its performance in any case. But also good monitor placement is crucial. If the singer moves out of the firing line of the treble driver in particular then she will not hear herself no matter how loud it's cranked. One unconventional solution that has always worked brilliantly for me in smaller venues is to have the monitor on a stand behind the PA speakers firing diagonally back across the stage. The horn directivity is optimal with this placement and you don't get so much sound bouncing off the ceiling muddying things up and hitting the mic from a bad angle. The bonus is the rest of the band hears the vocals more clearly too. I don't know why more bands don't do this for smaller stages, you need fewer speakers overall and you hear it better. Wedges are better for larger theatre-type stages where you can't get close enough to the performers without obsuring them otherwise.
BTW in my experience Mackie SM350s are a lot better than many dedicated monitors at the cheaper end of the market, plastic box or not.

[LawrenceH]

Oh, sorry for double posting, but although it's an 'industry standard' the SM58 is often not a great mic on female vox, especially through cheaper (read: not turbosound, nexo etc!) speakers. It does male rock voice very well, but for women it often lacks clarity and body in the mix which equates to not enough perceived volume and feedback problems. 9 times out of 10 I've had more success using a stage condenser with a bit of treble roll-off to tame feedback. Or the Sennheiser dynamics (e845/945 up). But mic choice is very much dependent on the voice, there's no one-size-fits-all solution so you HAVE to try them out for the person. Shure SM87a is often a pretty good bet though.
Food for thought, anyway.

[maxrossell]

[quote name='LawrenceH' post='657738' date='Nov 18 2009, 01:06 AM']Oh, sorry for double posting, but although it's an 'industry standard' the SM58 is often not a great mic on female vox, especially through cheaper (read: not turbosound, nexo etc!) speakers. It does male rock voice very well, but for women it often lacks clarity and body in the mix which equates to not enough perceived volume and feedback problems. 9 times out of 10 I've had more success using a stage condenser with a bit of treble roll-off to tame feedback. Or the Sennheiser dynamics (e845/945 up). But mic choice is very much dependent on the voice, there's no one-size-fits-all solution so you HAVE to try them out for the person. Shure SM87a is often a pretty good bet though.
Food for thought, anyway.[/quote]

I also agree with this. My backing vocalist uses a Sennheiser and it would be far better for a female vocalist than an SM58 as it doesn't have the midrange presence spike and flatters the bass end a lot, which is usually good for female vocals.

[Moo]

[quote name='velvetkevorkian' post='657563' date='Nov 17 2009, 10:26 PM']Moo, is the RTA just so you can see exactly which freqs are peaking so you can cut them more precisely?[/quote]

That is correct. I have a lot of experience as an engineer, but I cannot set an e.q. accurately by ear. The eq will vary with venues so I plug in the laptop, run pink noise through, and then adjust eq for flat trace on the RTA. Takes about 20 seconds. Its not always practical to do this in a venue full of punters, but you can make a note of your average settings, and run to those in venues where it is impractical to RTA.

Edited November 18, 2009 by Moo

[Moo]

[quote name='spinynorman' post='657626' date='Nov 17 2009, 11:13 PM']the SRM350 - it felt quite expensive to me, but agreed it isn't primarily a monitor.[/quote]

Plastic cabs are cheaper than plywood to manufacture, and lighter, which means cheaper distribution costs for the Manufacturer. Unfortunately that does not guarantee a cheap retail price.

My opinion is that I have never heard a plastic cab that I like the sound of.
They tend to have nasty resonant peaks in the high mids. That will exacerbate your low SPL before feedback problem.

EDIT:
I just remembered - I played a festival gig last summer where the Sound Co provided SRM350s for monitors.
I Sing B.Vs in my band. The monitors where painful and piercing when turned up, but were difficult to hear for pitch when singing harmonies. I think the problem is that they have a small 1" comp driver with a high crossover freq. This means the 12" mid driver is forced to operate up to a high frequency in its breakup modes, at which it becomes very directional.
The angle of the cab (45º IIRC) meant it was not pointed at my ear like a proper monitor, and the comp driver compromise meant that all the important frequencies were directed at my knees. At the higher frequencies that come out of the comp driver the dispersion was better, so I heard too much HF but no mids.
Overall Result: It was painfully loud, but I could not hear myself for Harmony vocal duties.

You will get best monitoring with Proper Wedges which point at the singers, and a good eq.
Either of those two will improve matters for you. The e.q. is probably the cheapest route in the short term.

Moo.

Edited November 18, 2009 by Moo

[spinynorman]

Lots of interesting ideas there - hadn't heard that about SM58s before, mind you the price of the SM87a is a bit eye-watering. Maybe look at the Sennheisers first. The monitor on a stand idea hadn't occurred to us and that would be easy to try next gig. And we'll sort out the EQ. Not sure my brain can cope with RTA software, but you never know.

Thanks for the ideas, everyone.

[crez5150]

Sounds like a prime case of going down the IEM route to me....

[Happy Jack]

Spiny, have you considered using feedback suppression?

I've used the Sabine 1020 and 2020 units with considerable success (and I am [b]NOT [/b]a sound engineer ) and the Peavey Feedback Ferret is also highly rated.

Beats the hell out of messing around with a 31-band EQ unit.

Are you anywhere near London?

[spinynorman]

Well, the only idea we could try at last night's gig, since we happen to have a spare stand, was to put the monitor up at ear level at the side of the stage. And ....... IT WORKED! Only downside was I had to be more careful where I stand, but she could have all the volume she wanted, and no feedback. On-stage sound generally seemed clearer. By the end of the night I was looking quite smug (guitarist was hugely sceptical).

@Happy Jack: I've had mixed advice about feedback destroyers, brilliant or useless depending who you talk to. Was it you that was selling the Sabine and Peavey ones a while ago? I did seriously think about it, but didn't go for it in the end. I'm in leafy Warwickshire BTW.

I think we'll still have to do something about the EQ, as the side monitor won't be possible everywhere, but looks like that's cracked it for most places. LawrenceH, you're a star.

[Happy Jack]

[quote name='spinynorman' post='660249' date='Nov 20 2009, 03:43 PM']@Happy Jack: I've had mixed advice about feedback destroyers, brilliant or useless depending who you talk to. Was it you that was selling the Sabine and Peavey ones a while ago? I did seriously think about it, but didn't go for it in the end.[/quote]

Yup - they're out on test with another BassChatter and his band at the moment.

[LawrenceH]

[quote name='spinynorman' post='660249' date='Nov 20 2009, 03:43 PM']Well, the only idea we could try at last night's gig, since we happen to have a spare stand, was to put the monitor up at ear level at the side of the stage. And ....... IT WORKED! Only downside was I had to be more careful where I stand, but she could have all the volume she wanted, and no feedback. On-stage sound generally seemed clearer. By the end of the night I was looking quite smug (guitarist was hugely sceptical).

@Happy Jack: I've had mixed advice about feedback destroyers, brilliant or useless depending who you talk to. Was it you that was selling the Sabine and Peavey ones a while ago? I did seriously think about it, but didn't go for it in the end. I'm in leafy Warwickshire BTW.

I think we'll still have to do something about the EQ, as the side monitor won't be possible everywhere, but looks like that's cracked it for most places. LawrenceH, you're a star.[/quote]

Yes! Ever since I tried this, it's been my first-try solution to problem monitoring, and I feel like a crazy TV evangelist when I've told others to try it, because no-one else EVER seems to suggest it - really happy to hear you tried it and it helped

A lot of people don't even bother trying I think, there's almost this idea that to sort out a problem you need to spend money, preferably lots and on something hi-tech (!). But a few years doing student gigs in cramped spaces where venue budgets were limited taught me that if you can get the acoustics of the stage right most of the problems just disappear. My other absolutely top tip for live bands playing indoors is to hang stagecloth behind the drums. Makes a massive difference to early reflections which muddy the sound and contribute to feedback, so you find you don't need to be as loud to hear yourself, and you've earned yourself extra headroom anyway - win-win.

I think as you say, long-term EQ is still an invaluable tool. I'd have it even with the monitor on the stand. But if the monitor placement is sub-optimal in relation to your ears then with all the technology in the world you're still fighting a losing battle.

Feedback destroyers - the Sabine are supposed to be better than the Behringer. But personally I find them a bit unnerving because they're a 'magic box'. You can't directly see what they're doing on automatic mode, which is fine when it works but if it gets in a tizzy it can do REALLY strange things to the sound. If you set them manually then really they're no more efficient than a 31-band and if you get a new feedback frequency mid-gig it's harder to dial out. I'd just go for a 31-band, they're easy to get the hang of and much more hands-on intuitive IMO.

Edited November 21, 2009 by LawrenceH

[thinman]

We use some cheapo Thomann active PA speakers for vocal monitors and on their own they're a nightmare for feedback - probably because they've got a very peaky response - so much so it wasn't possible to get any useful volume out of them. I tried a Behringer feedback destroyer in the feed to the monitors and found it wasn't a great deal of use.

I'm not suggesting this wholly as an alternative to good mic and monitor placement but it helps enormously.

A 31-band graphic was the answer (althought some people use 3 or 4 -band parametrics.). We've only got a limited budget so we have a Behringer 3102 which has LEDs on each fader. We run the PA in mono using one side of the graphic for FOH and the other side for the monitors. It's really easy to use to "ring out" the PA. It's not often necessary to ring out the FOH as the monitors are the main culprits.

Ringing out: Do the monitor feed only with the FOH turned down. Set the graphic flat. Set the mic gains about right then turn up the gain to the monitors until feedback starts. On the Behringer the slider associated with the feedback frequency will light up so you notch that down a few dB. You bring up the gain again and feedback will occur at another frequency (or the same one as before if it wasn't cut enough) so you notch that one out a bit too. You usually have to repeat about 3 or 4 times. When you get to the point that there are multiple frequencies feeding back at once then you've done as much as possible. You then have to drop the gain back to not "ring".

I also tend to cut below about 150Hz as it's a waste of power for vocals.

[Phaedrus]

I've run our PA for all of our gigs for the last three years, and we always struggled with hearing our own vocals onstage while not suffering feedback.

I can't offer any magic solution or fix-it product, but I'll make my comments in case they help.

We have a DBX driverack PA which has a feedback destroyer built-in. It's slow to eliminate any squeals and only remembers 12 squeal frequencies, though TBH, if all 12 were ever all active at the same time, I'd probably just pack up and go home.

We also have a DBX 231 dual 31-band graphic EQ. I put this in the monitor chain (leaving the DRPA handling just FOH) and found that I was able to run the monitors louder and cut any squeals that tried to happen. An EQ with LEDs in the sliders is a great idea. The monitors are HK RS122MA active jobbies - claimed to be 120w, but I think they're inefficient and have poor tonal characteristics. Any increase up the market scale doubles their price, and we run 4 of them, so we got what we could afford.

The most effective thing we did that stopped feedback was reduce our on-stage volume. We only dropped a little, but left the monitors as high as we could, and we could hear all we wanted just fine. We also made sure we always placed both the mics and the monitors so there was as little opportunity as possible for a squeal to circulate once it started. We also spoke to the lead singer about good mic technique - for what we're doing, that means lips on the mic except for the screams, never point the mic at a monitor, never let the mic point into any of the FOH speakers.

We also ran the PA as an aux-fed subwoofer system which [b][i]really[/i][/b] helped clean up FOH, but that's a bit of an aside.

Most effective fix? Reduce on-stage volume.


Mark

[King Tut]

I regularly use a Behringer feedback killer in line with our two monitors - and we hardly ever have feedback problems. I also use a graphic inline - I play piped music through it and try to eq out anything that sonds unnatural, and routinely cut the top and bottom couple of bands.

[LawrenceH]

[quote name='Phaedrus' post='661495' date='Nov 22 2009, 01:00 AM']Most effective fix? Reduce on-stage volume.


Mark[/quote]

+1. Noisy drummers/guitarists cut right into the vocal frequencies.

[Count Bassy]

Great thread chaps - We've been having very similar problems in rehearsals so some good ideas to try out here.

We have a female singer and although her pitch and tone are good she doesn't belt it out particularly loud. Also not helped by the fact that she only has a cheap mic (SM48?).

Oh - and a guitarist who only has one volume doesn't help (he is partially deaf which can't help), although he is working on this and it's getting better.

I'll try out the side fill monitor idea at our next 'full PA' rehearsal.

Edited November 22, 2009 by Count Bassy

[spinynorman]

Cutting on-stage volume is a nice idea, but I rarely get my volume knob above 2.5, which is as low as it'll go without losing all the tone. Guitarist is in a similar situation. I've got a 50w Crate combo, which in a lot of places we play would be enough, but audiences - and landlords - seem to expect at least a waist-high pile of gear, even in a broom cupboard with a bar.

We did a straw poll of some bands who inhabit the same circuit, expecting someone would have cracked the problem, but they all said they couldn't hear their vocals either. Someone should write The Basschat Guide to Cheap PA, it would sell.

@Phaedrus: I saw some reviews of the dbx231 that said it was noisy. How have you found it? It's a bit more expensive than the Behringer, so I was expecting it to be better.

Edited November 26, 2009 by spinynorman

[LawrenceH]

[quote name='spinynorman' post='666203' date='Nov 26 2009, 01:28 PM']Cutting on-stage volume is a nice idea, but I rarely get my volume knob above 2.5, which is as low as it'll go without losing all the tone. Guitarist is in a similar situation. I've got a 50w Crate combo, which in a lot of places we play would be enough, but audiences - and landlords - seem to expect at least a waist-high pile of gear, even in a broom cupboard with a bar.

We did a straw poll of some bands who inhabit the same circuit, expecting someone would have cracked the problem, but they all said they couldn't hear their vocals either. Someone should write The Basschat Guide to Cheap PA, it would sell.

@Phaedrus: I saw some reviews of the dbx231 that said it was noisy. How have you found it? It's a bit more expensive than the Behringer, so I was expecting it to be better.[/quote]

Stagecloth. Loads of it, especially round the drums. In a venue with hard surfaces, it's like aural magic.

Powersoaks on the amps is another option to wring more tone out of the amp, though this won't give you speaker distortion. But really, getting amps that sound good quiet is just a more elegant solution.

The guide is a good idea, but really the answers are all out there, it's just a question of whether people are prepared to implement them. Make sure amps aren't firing into vocal mics, you can even fire them crossways (this works well) if you don't mind the look.One really fundamental problem is that people have an idea of how a band 'should' look set up, but that idea is based on how soundsystems were 30+ years ago and often in venues that have totally different requirements than your average British gaff. Mics in the past were expensive, and PAs were crap. But if looks are a problem then you can 'fake' it in various ways, just use dummy gear.