L3T first use.... wow the feedback!!

[padolin]

I just downsized my PA system from somthing that I used to tow in a trailer to 2 L3T's and a Alesis multimix 12 firewire mixer.  I have only used the mixer a few times and Im not very familiar with it.  Its been in storage for a few years. 

 

So i just recieved my 2 L3T's this week and was anxious to use them.  A friend of min was playing a local gig and i volunteered to run PA.  His show consisted of a telecaster, a washburn acoustic, two vocals, an upright bass and a small drum kit.  We ran everything except the drums through the mixer and the two L3t's. 

 

First off, the guitars and the vocals sounded great through the PA.  On the other hand, the bass produced a really nasty boom throughout the whole show.  Also, I belive there was quite a bit of low end feedback through the vocal mics and the acoustic guitars.  Most of it was managable, but it was there.  The bass feedback was horrible though.

 

Has anyone noticed feedback issues useing a system similar to this?  Does anyone have any suggestions?  I may need to just get this system figured out some more and maybe get an equalizer or something. 

 

Thanks for the input!

[Rick_Auricchio]

It sounds like there was just too much bottom end dialed in for the bass channel. Besides feedback and boom, doing that causes the bass to mask a lot of the rest of the sound from the PA, which ruins overall sound.

 

If the bassist wants bottom-end, he should bring his own amplifier. Take a direct-box (DI) from the bass (or the amp) to the PA. Then his amp provides bottom end to the audience, and it provides stage volume for the band. Just have the PA reinforce the upper end of his sound, which is all you'd need for the audience. Then, by reducing the bass with EQ you keep it from booming in the PA, and the audience hears all the upper nuances of the bass.

[dboomer]

Your feedback is happening because the lows coming from the system are getting back into your microphones.  You need to either turn down your mics, turn down your lows or move the speakers further way from the microphones. (or all three).

 

You could also try turning down the lows on the mic channels.

[BucF16]

Output knobs on the back of the speakers should be in the notch, not cranked.

 

I would say your problems are not typical of the speaker per se as I've experienced.

[ArneLine6]

A high pass filter on the mic channels will probably solve this problem. It filters out the low end that is not helpful for vocals anyway. If you don't have a high pass try using the low frequency eq, like Don said.

[Rick_Auricchio]

All of the above!

[padolin]

Yeah, thats what i was hoping to hear.  I noticed that the bass players bass amp was a wedge type and was pointing right toward the back of the singers heads.  Also  he was singing into a dynamic mic which may have added to the problem. 

 

I had the knobs one mark past the notch on the speakers.  next time ill back it down a bit.  After reading some things on here i see that may have added to it.  (why let the knob go past the notch if that is optimum?....  hmmmm....)

 

high bypass filter??  not heard of such a thing??

 

Never thought of a direct box!  ill try that next time

 

Been away from this sound/ music thing waaayyyy too long!!!

 

Thanks for all the help!!

[Rick_Auricchio]

"...the bass players bass amp was a wedge type and was pointing right toward the back of the singers heads."

 

Try positioning the amp pointing at the band like a monitor wedge. This allows the whole band to hear the bass, and the bottom-end of the sound will still be heard well in the house. (Bass is nondirectional.) It also allows you to cut its volume to minimize stage volume. The top end won't get to the house from there, but that's why you add a little in the PA. With EQ cutting the bass in the PA, of course. Now the audience has the full sound of the bass.

 

The dynamic mic isn't an issue: most mikes will still pick up the low end more than you need.

 

re: Highpass filter. Most mixers have a highpass (also called low-cut) filter. Usually it's engaged by a button near the mic gain knob. This filter typically rolls off everything from 80 or 100Hz downward. It cuts p-pops from microphones nicely. Men's voices rarely get below 80Hz; women's voices don't go down that far at all.

 

As for a DI, even a low-cost passive one is handy to carry; it can solve lots of problems. For many instruments a passive one is just fine. The LiveWire SPDI ($30 at Musicians Friend) is small and only weighs 12oz.