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[Al Craig]

Hi experts!

I have been struggling to get lav systems working for my live sound needs. Primarily doing business conferences for 50-60 people. Here is my gear:

2x QSC CP10 speakers
Mackie ProFX10v3 Mixer
Shure BLX wireless systems with handheld and lav transmitters
Shure lav mics
DPA headset
Sony UWP-D Wireless System with Sony lavs (cardioid and omni)

Whenever I use the Shure handheld mics or the DPA headset mic the sound levels are good. Whenever I use the Shure lavs or Sony system with its lavs the sound levels are too low or start to provide feedback. I have tried various settings of gain staging, connecting directly to the QSC speakers bypassing the mixer, and anything else I can think of but the results remain the same.

What am I missing here?
Should this setup work? How are others using Shure BLX lavs for similar work?

Thanks in advance!

[Mac Kerr]

Hi experts!

I have been struggling to get lav systems working for my live sound needs. Primarily doing business conferences for 50-60 people. Here is my gear:

2x QSC CP10 speakers
Mackie ProFX10v3 Mixer
Shure BLX wireless systems with handheld and lav transmitters
Shure lav mics
DPA headset
Sony UWP-D Wireless System with Sony lavs (cardioid and omni)

Whenever I use the Shure handheld mics or the DPA headset mic the sound levels are good. Whenever I use the Shure lavs or Sony system with its lavs the sound levels are too low or start to provide feedback. I have tried various settings of gain staging, connecting directly to the QSC speakers bypassing the mixer, and anything else I can think of but the results remain the same.

What am I missing here?
Should this setup work? How are others using Shure BLX lavs for similar work?

Thanks in advance!

It’s impossible to know without being there, but my guess is unrealistic expectations.

Mac

[Tim McCulloch]

Hi experts!

I have been struggling to get lav systems working for my live sound needs. Primarily doing business conferences for 50-60 people. Here is my gear:

2x QSC CP10 speakers
Mackie ProFX10v3 Mixer
Shure BLX wireless systems with handheld and lav transmitters
Shure lav mics
DPA headset
Sony UWP-D Wireless System with Sony lavs (cardioid and omni)

Whenever I use the Shure handheld mics or the DPA headset mic the sound levels are good. Whenever I use the Shure lavs or Sony system with its lavs the sound levels are too low or start to provide feedback. I have tried various settings of gain staging, connecting directly to the QSC speakers bypassing the mixer, and anything else I can think of but the results remain the same.

What am I missing here?
Should this setup work? How are others using Shure BLX lavs for similar work?

Thanks in advance!

What Mac said.  Start with the lav system as the 'setter of expectations' and then match the ear set and stick mics to the lavs.

The gain you need is not electrical.  What the stick mics and ear set mics have in common is (typically) being closer to the mouth than a lav can be positioned without creating other complications.

The inverse-square law is not your friend here.  With an ear set mic about 20mm from the corner of the presenter's mouth, to have equal level at a mid/high chest postion, a lav needs about 24dB more input level, or 24dB more electrical gain.  The latter amplifies room and HVAC noise, clothing noises, all the sounds... by 24 dB.  And it reduces your gain before feedback by 24 dB compared to the ear set.

If you've not already done so, disabuse yourself of Mackie's "unity."  Like " 'normal' is just a setting on the clothes dryer", 'unity' is just a label on the panel.

The high pass and low pass filters on modern compact digital consoles can be very helpful in live situations, along with have full parametric filter sets on each input and output.  You may wish to explore other mixer options with a larger feature set but starting with expectation management will help.

Finally, post-mixer, most systems have too much gain.  A common rig in my old shop was JBL VerTec 4887 in ballrooms, ITech powered.  The Itech input sensitivity were set for 26dB gain and to get useful meters and compressors on the console, I lowered the input trim -6dB on each amplifier channel, too.  For fun we switched the amps to 1.4v sensitivity and OMG was it loud and comparatively noisy.

Carefully done, a 4 member panel discussion on stage with a host/emcee on lav mic, downstage of the PA in the audience was entirely possible with that rig, my tuning, and having really good presenters.  You're using different gear but the basic principles are the same.

Get your CP10's up as high as you can and aim them down.  This does a couple things:  it puts a little more distance between the loudspeakers and the mics and lets the "other side" of the inverse square law work for you with more even coverage of the audience area.

Accept that in some rooms it may be better to patch into the house overhead speaker system.  You'll still need to do your normal stuff and you may want to keep your PA (especially subwoofers) "perceptibly" on (clients who listen/pay with their eyes) but this can work in rooms with low ceilings or where you can't get your PA up as high as it needs to go.

Good luck, and let us know how things work out.

[Thomas Le]

What lav specifically is it? Usually with lavs you will need to EQ the heck out of the channel/system to get something remotely acceptable. For something cheap and "need it now", a used 31 band GEQ or PEQ rack unit could solve the issue, otherwise as Tim as alluded, you may need to get a better mixer for the job.

[Mike Caldwell]

Another plus to a digital mixer in addition to the processing is quite a few offer an "auto mix" function that helps when using multiple mics that are all open at the same time for events like are doing by averaging the gain between the mics as needed depending on how many are in use.
You don't need to buy a mega thousand dollar mixer to get that option either!

[Steve-White]

Stage plot close to scale would be real helpful.

[Kelly Mcguire]

What lav specifically is it? Usually with lavs you will need to EQ the heck out of the channel/system to get something remotely acceptable. For something cheap and "need it now", a used 31 band GEQ or PEQ rack unit could solve the issue, otherwise as Tim as alluded, you may need to get a better mixer for the job.

Thomas has the quick, inexpensive solution. Your Mackie mixer doesn’t have a mains EQ that would allow you to ring out the system, getting you much more volume before feedback. The Mackie is broad stroke butter knife EQ and you need razor sharp scalpel.

Tim mentioned getting the CP10 up in the air. That’s important and free for the most part(unless your stands won’t go up high). Ultimate support TS88b tall stands would be great but $100 each. Also a lot of the plastic speaker’s cabinets just aren’t damped enough, allowing resonance ringing on LAV and regular dynamic mics as well.
 As also mentioned, every inch closer to your mouth the mic can get will help that inverse square issue, 6dB loss every doubling of distance or 6dB gain when you halve the distance to the sound source.

Again, find a used 31band DBX, Peavey or Rane EQ. Get yourself an RTA app for your phone. Engage the HPF switch on the mixer channel.  Have presenter stand on stage, turn up the system right to the edge of ringing. What frequency is showing on your phone? Turn it down on the EQ and push up the level a bit more. When a few frequencies are ringing that’s about all you’ll get out of the system.

[Riley Casey]

Suggestions in order of value

1 - Use only cardioid lav mics, leave the Omnis for broadcast use
2 - Use an automixer for any more than a single lav on stage. Yamaha mixers & some Behringer mixers have them built in. A low budget solution is a used Shure SCM810. Plug the lavs into that & that into the Mackie
3 - Design the sound system for success. Don't try to throw to the back half of a long narrow room from a pair of speakers at the front. Use delay speakers halfway back to support that so that the main speakers run at a lower level
4 - use appropriate equalization - the channel strip isn't that - a third octave unit between the automixer & the main mixer would be an option
4 - hi pass the lavs higher than you think appropriate. 200hz for male voices, 250 for female

[Don T. Williams]

All of the above.  I have also found that the Automatic Mic Mixing functions really help with multiple mics.  I have also had very good results using the automatic feedback filters on the QSC Touch Mix and the A & H new CQ series digital mixers.  Because the filters are so narrow, they leave more audio than a 1/3 octave graphic, and the auto function works well. Most 1/3 octave graphics have filters that are 1 to 1&1/2 octaves wide.  The center frequencies are on 1/3 octave centers, but the cuts on most are pretty wide and take out a wide swath of information.

[Steve-White]

Get a small digital mixer and learn how to use the parametric eq functions - you can do this easily at home.  Hacking away with a graphic eq to reduce/eliminate feedback is like trimming your finger nails with a hatchet.

[ProSoundWeb Community]