Re: Slightly OT: using mics live etc

Our band always has trouble getting the vocals, mainly our female lead
singists volume high enough in the mix without causing feedback problems.
For instance last week in rehearsal we were using a 350w per side PA, and
still had trouble getting her heard above drums, my bass and 2 guitarists.
Obviously we can only play as quiet as the drums. Now Jenny has a cracking
sounding voice, it's just not a massively powerful one. She can sometimes
belt it out, just not often. (our drummer on the other hand has a naturally
loud voice and has to be turned right down).

We also have problems at gigs too. One of the guitarists dads is our
soundman and he always has trouble getting her heard, even with a 1.5kw PA
and shure wireless SM58 mic. He has a feedback destroyer, but it can only
do so much. We're also playing a gig soon in a pub with a very low ceiling
that we had so much grief with before. The mics (mainly hers) were turned up
so much the drums started feeding back through them.



I think all bands, to quote Ian Gillan, try to have 'everything louder than everything else' at times. I know ours does :-).... and aren't drummers annoying when in rehearsal the other members are trying to communicate verbally, and every time you open your mouth to speak, they insist on repeatedly playing Ian Paice's intro to Deep Purple's Fireball? Also applies to guitarists/bass players/keyboard players when the drummer needs to know something except it's not usually Fireball as that's a drummer thing...

To counter feedback problems with our own PA, we've tried various decent mic's without wanting to pay silly money, changes to EQ settings and a feedback destroyer or two. As another poster said using a feedback destroyer is not necessarily a good idea on the whole mix as you can end up with a situation whereby the FOH sound ends up sounding more than a bit nasal like it's coming out of a pair of megaphones rather than a reasonably well specified PA system. We found the FB destroyer to be most effective on individual vocal mic channels, but it's rarely used now.

Isolating the exact cause of feedback can be difficult, but re-aligning the angle of wedge monitor to mic or FOH speaker to mic can sometimes help pinpoint the cause as the feedback will either stop or get worse. Once the cause is more or less known, you can begin to treat it

The problem we have as will be the case with most bands I guess, is that we are a classic heavy rock band and it's kind of expected that we will be loud. There's one thing being just loud and completely another thing being just perceived as loud. The latter is what we aim for, but don't always achieve because in plain terms we lack some discipline as a band. We don't have a sound man as such, which I personally believe is a problem, but the bass player and I separately record other bands and/or provide PA hire for them, so we volunteer/get roped in to set up the PA on a 'leave it alone' after the sound check basis.

From years of playing in loud bands as we all have, one of our our main
vocalists, by his own admission has less than optimum high frequency hearing and it's worse in one ear than the other, so he always goes out front demanding 'more top' which opens the flood-gates for feedback problems. We have to lie to some extent and back the 'top' off again when he's back on stage, and then go and listen ourselves. Of course he then wants 'more top' in his monitor wedge too - but he's now got personal in-ear monitoring so that gets around that problem.

Although we usually put everything through the PA to a greater or lesser extent including drums and back-line unless the venue is tiny, the on-stage sound is quite loud anyway. As you'd expect if thinking logically, ears are sensitive things and after about 15 to 20 minutes playing time, they get tired and that's when the real trouble can start. A guitarist who shall remain nameless then starts to think he isn't being heard properly out-front, so he sneakily turns round and ups the volume on his Marshall to 11 when he thinks no-one is looking. This affects the singer's ability to hear himself, and the rest of us having seen the sneaky volume thing by the other guitarist, not-so-sneakily up our levels too. It can become a vicious circle. In fact nothing out-front has changed until the back-line volume creeps up. Apart from it being a complete waste of time to have a sound check in the first place, the only thing that has changed is the current ability of our ears to hear properly, and as a result our own confidence in our ability to be heard is reduced resulting in all of us over compensating. Of course prolonged exposure to high levels of sound causes permanent damage to hearing. A good case for plug-in ear defenders all round I'd say.

The environment/room itself makes a hell of a difference to the band's own perception as well as the potential for feedback. For example, my band has the choice of two different rehearsal rooms. The first is basically an abandoned factory unit on an industrial estate which is essentially about 20ft wide, about 26ft long and about 12ft high. It has a concrete floor, concrete block walls, and a concrete ceiling. No carpet or other furniture. It's a terrible rehearsal environment as all the walls ceiling and floor are all hard reflective surfaces and any sound simply bounces around and finds its way back quite easily into any open mics. The other room we use was originally set up in the middle of nowhere as a recording studio, but strangely has never had any recording gear installed (so we take our own for recording sessions). This room is just the opposite of the first in that the flooor, walls and ceiling are carpeted, there's plenty of absorbent rock wool in the walls, and apart from the control room window which is angled, there are no hard reflective surfaces. In this room we can play pretty much as loud or quitely as we like within reason without feedback and everything is really clear. The main reason for this is the fact that very little sound is reflected back into open mics having been absorbed by the soft carpet and underlying rock wool. This is a very controlled environment, and we like it a lot, so use it whenever it's available.

Ok that's two extremes, and a standard live venue usually falls somewhere in between. If you have any control over the environment you rehearse in, you will probably find that although you can't rebuild a room so that walls don't run in parallel and the ceiling is lower at one end than the other, strategically placed rugs or carpets on the floor and soft furniture placed in corners and curtains on some of the walls and if possible, ceilings, will help prevent too much reflected sound. It's good to keep a room a bit 'lively' but not too much. Doing this (if you can) will probably give you a result more akin to a live venue with a crowd (remember, bodies are soft and absorb a lot of high frequency sound). I don't pretend to know a lot about the maths and physics behind the acoustics of a room, but I do know that playing about with a bit of carpet, sofas, chairs and drapes on walls can help quite a bit in defeating feedback issues.

In a live situation, the sound when there is no crowd say at sound check time will usually be more lively than when the crowd is there becuase of the crowd's mid and high frequency sound absorbent properties, and it is usually possible to lift the level of open mic's very slightly more than at sound check time without getting feedback.

Most mic's come with a data sheet which usually has a diagram of the mic's pickup pattern and which also highlights the areas surrounding the mic in which it will be the most sensitive and the areas in which the mic will reject incoming sound. It helps if unlike most vocalists, you don't throw this in the bin :-) Some mic's even have a little bit of paper or a card which lines up with the axis of the mic and which gives the optimum angle and distance from the mic for foldback monitors. It's different for different mics obviously as some are better at rejecting sound form the rear and sides than others, but in essence this means that in a lot of cases placing a wedge monitor directly behind a mic stand does not offer the optimum feedback rejection opportunities you might think it should. It's important that a vocalist can hear the band properly, and more importantly can hear themselves well enough to deliver a confident and in-tune performance. Most wedges monitors are angled at about 45 degrees from vertical. The idea is for the sound from a monitor wedge to make it by the most direct route to the singer's ears, and not to their knees or a point on the ceiling behind them. The optimum distance from the singer's head will be determined by the height of the singer's ears from the ground. Therefore a 6ft singer's ears will be about 5ft 10in from the ground, and the monitor wedge(s) should ideally be placed somewhere on an arc whose radius is centred on the main position of the singer's feet. Rather than placing a monitor wedge directly facing the singer in-line with the mic's axis, you will probably find that placing the wedge(s) between 30 and 45 degrees off axis from the rear of the mic will give the best results in defeating feedback at higher volumes.

The use of a graphic EQ just on the foldback system can help as well b y being able to sweep for the offending frequency and being able to notch it out. A compressor and a noise gate used sparingly and both with a fast attack and slow decay will help both even out the sound of the vocalist and also effectively switch the mic off when the singer isn't singing, thereby significantly reducing the potential for unwanted feedback. A noise gate might noticeably clip the start of vocal phrases if the attack isn't fast enough We are quite fortunate in having a digital mixing desk with good channel EQ, compression and gating as well as on-board FX, and we find this helps a lot. Whilst we never go anywhere near maximum output, our FOH PA consists of a couple of 600w powered bass bins, a couple of mid-high 1000w/2000w max passive cabs powered by a 2600w power amp, a couple of 350w powered mid-high cabs which we can use either for a bit of reinforcement out front or as monitor wedges/side fill, and 3 powered on-stage monitors. In most places we don't need the side fills or FOH reinforcement, but there are some places where it helps.

Mic-wise, we don't have anything particularly special - just the usual suspects in the main: SM58's (the older US made ones seem more powerful and less prone to feedback, but that may just be our imagination), SM57's, AKG D112 for the kick drum, a couple of AKG C1000s condensers, and most recently I got a couple of Shure Beta 57 mics, which we find are good on vocals giving high output and low feedback characteristics - but they probably won't suit every vocalist. Our bass player has a couple of Shure Beta 87 mics, which are a bit more special for our singers and less prone to feedback and he occasionally brings them out.

Some mic's like the AKG C1000s come with a cap that fits on the capsule and changes the pickup pattern characteristics when fitted. Note: we don't generally use the C1000s for vocals in a live situation - not sure why really - it's just we've never really tried it probably as these are condenser mic's and the (probably wrong) perception is that they'll feed back more easily :-) Some mics have the ability to roll off low or high frequencies as well.

All things considered, including the lack of discipline at times, and lack of a body to man the desk we invariably get a good FOH sound with little or no feedback problems, purely by correctly placing foldback wedges, keeping the overall level below feedback thresholds and using reasonable microphones.

We are quite fortunate in having two good male vocalists with powerful but quite tonally different voices. One is particularly reminiscent of classic blues-rock singers like David Coverdale and Paul Rodgers and has a particularly rich sounding voice, and the other is more akin to heavy metal singers like Bruce Dickinson and Rob Halford. Capturing a sweet female vocal loudly enough can be much more of a challenge, particularly if it's not a loud characterful voice that can always belt it out. Maybe changing the key on some songs might help, particularly if she's not always singing in a key that's particularly comfortable for her. Not always possible I appreciate.

We can't always do this, but if we can get to a venue in the afternoon before a gig we can spend as much if not more time getting the on-stage sound right before starting on the FOH sound, and when we do have this opportunity, it almost always pays off. There's really nothing worse than trying to sound check with a room full of people, but it's not always under our control.

Having the opinion out-front of someone with good ears and who you trust is invaluable even if they aren't mixing the band. There is always a temptation to listen to Joe Public mid-gig, who is invariably three sheets to the wind, a mate of a single band member, not a musician and who just wants to hear his mate louder than everyone else and to alter the mix on his say-so. Enter potential for feedback problems....

In your case I woud suggest that your vocalist tries a few different mics with a view to finding one that best suits the characteristics of her voice without overemphasising feedback prone frequencies whilst giving maximum output. While a standard SM58 may be OK for her, the chances are that there will be something more suitable in the Shure range or from another manufacturer. This may take her a little time, and the co-operation of a local music shop if they'll lend her a few mic's to try as long as she buys one at the end of it all and paying a little more than an Internet price is probably worth it to get the right mic

Also, if your singer is self-taught as most are, going to see a vocal coach with a view to learning better voice projection techniques might be worth considering. Add to this, microphone technique.

Keeping the levels down is good too if you can achieve this. I find using one of Line 6's modelling guitar amps gives me more than enough volume if needed but more importantly it gives me a usable tone at lower volumes and I'm using my Marshall TSL100w setup less now.

It's only the view of a practising live musician and our experience within our own band, but I hope it's given you some things to think about trying.

IMO, there's no substitute for having a sound engineer who has good ears and knows what he is doing really though and 'one of the guitarist's dad's' might not be the ideal choice - particularly if he's never done any other sound related work or training - even going out occasionally with another band's sound guy to assist and learn how someone else does it.

Nick


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