Which Mixing Desk

[winker]

Hi Everyone I've just registered so I'm brand new to this forum but would like to take immediate advantage of your knowledge and experience.

 

My band recently bought two Mackie powered speakers and bass bins to replace the Wharfedale system we had previously and the sound difference is amazing.

 

We currently use a Behringer SL2442 FX Eurorack mixing desk but are considering buying the Mackie 1642 VLZ3 desk. We DI everything through the desk and although we still rely heavily on the back line the desk is used to balance the sound out front.

 

We've recently been experiencing problems with feed back which only happens at higher volumes and our drummer thinks it's because the desk isn't up to scratch.

 

Can anyone advise on what benifit we would get by changing the desk or is the answer too obvious. Please be honest - I'm not easily offended.

[Rob_Beech]

Welcome.

 

There are lots of things that can cause feedback to occur. The quality of the desk is not one of them (directly). Insufficient eq control on the desks inputs and/or outputs however CAN contribute towards feedback, as can low quality preamps and other circuitry that gives a far from linear response when driven hard.

 

Feedback can be reduced in a number of ways, one of the easiest is to use EQ, but positioning of speakers, positioning of mics, and overall volume both on and off stage are the ones to look at first.

 

There are a number of topics about reducing feedback and the likes here. Have a look around.

[Sirch Sound]

Ok, to expand on what rob said a bit.

 

Basically feedback is primeraly caused by the mics being lound/close to the speakers. (yes I know, thats a very, very simple explenation and not entirely right but it will do for explaning this problem). You are experiencing Feedback basically because your trying to push your mics too loud whilst having them too close to the speakers. As rob mentions, there are neumerous ways to cure this problem. The simpliest and cheapest is either to turn down you backline gear and therefore your FOH aswell, or move your speakers forwards/mics back, to create a bit of distance between them.

 

However this will not give you that greater difference, unsless you move them substantialy. The proper way to get rid of feedback is by using an Equiliser, commonly refered to as an EQ. The best in my opinion for this type of job is a graphic Equiliser (GEQ), others dissagree however im not going to get into that debate now. Basically only certain frequenceys of the mic will cause feedback, and you can cut (get rid of) these frequenceys using an equaliser. This way you can push the mics harder without getting feedback, however you cannot cut too many frequenceys otherwise your mics will sound crap. Usualy practice is to cut 4-5 frequencey bands.

 

The tricky part is detecting what pitch the feedback note is to cut it. If you carnt do this by ear, and it takes practice, then you have a couple of options. You can use a feedback destroyer, which basically cuts all of the problem frequenceys automatically, which sounds great! However most people belive they tone the sound quite alot and dont make it sound very nice, hence the reson most professional sound engineers refuse to use them. The second option, and my prefered option, is to use somthing like the Behringer FBQ range. This range of graphic equalisers illuminate, using LED's, the frequencey bands that are feeding back and you can then pull that slider down. Its very quick and very simple, and allows you much more control of whats going on than a feedback destroyer would.

 

This is only a very quick and simplified guide, and in reality its ALOT more complicated than this, however this info should be enough to get you by.

Hope this helped

Rich

[winker]

Thanks for the replies and I think I need to add a bit in relation to the problem. We don't think it was just the mics feeding back as we are normally quite specific in where they are located in relation to the speakers. We think the problem may have been caused by my acoustic guitar and here's why :-

 

I use electric and acoustic guitars at gigs and last night at a gig the feed back problem was a nightmare. In the first set I do four or five numbers with an acoustic which is set up as follows[/font] The guitar is a Taylor 314 with the expression system which I put through an AER compact 40 amp. I then take a line from the DI out into one of the mic XLR sockets on the desk however even with the desk gain turned right down it still clips on the desk LED's. I only need the amp as a monitor so I can hear what I'm playing but the drummer complains that he can't hear it so always wants it turned up and he is a loud drummer. After the first set I turned the amp off and there didn't appear to be any feed back after that. If you're familiar with the gear I'm talking about can you suggest a different set up because I'm on the verge of selling it or punching the drummer.( Unfortunately he is very good) Additionally I stand the amplifier right next to my electric guitar amp which is a Marshall TSL 602 and when I'm playing acoustic the guitar signal to the Marshall is switched off via a foot pedal. Both are facing front of stage.

[Pyramid]

....I then take a line from the DI out into one of the mic XLR sockets on the desk however even with the desk gain turned right down it still clips on the desk LED's.

 

 

Hi Winker

Problem you have here is that the signal level from you amp (DI out) is greater than that which can be handled by the mixer. This is, in all likelihood caused by you turning up the input gain on your amp so that the drummer and you can hear it, thereby increasing the output level also. Some desks have a pad or attenuation button, (normally located about the gain on the channel strip). If your desk doesn't have this facility it possible to attenuate (reduce) the signal by using a DI box connected from the line output (as you do with other instruments) or an in-line attenuator.

 

Andy

[MarkPAman]

I then take a line from the DI out into one of the mic XLR sockets on the desk

 

As far as I can see, the DI out on your amp is line level, the XLR in on the desk is mic level. So it's much too loud for the desk, (which does not have a pad).

 

Option one: Plug into a line level input on the desk. Cheap & simple provided the desk is near the amp.

Option two: Plug into a DI box, then plug that into the mic input of the desk. Better opotion when the desk is further away.

[Bobbsy]

The desk doesn't have a pad switch but I believe the "Line Input" TRS jack next to the XLR on each channel strip is set up to accept line level inputs. One XLR to TRS adaptor and the clipping issue should be resolved.

 

This is not to say that eventually a better mixing desk wouldn't be a good investment. The Behringer mixers are excellent value for money but, in terms of sound and longevity, aren't in the same league as things like Allen & Heath, Soundcraft and others in the next step up from there. I personally wouldn't recommend the Mackie. Although more money, they aren't much of a step up from the Behringer. However, when you get a new desk, do it for the right reasons...and curing feedback isn't one of them!

 

Bob

[winker]

The desk doesn't have a pad switch but I believe the "Line Input" TRS jack next to the XLR on each channel strip is set up to accept line level inputs. One XLR to TRS adaptor and the clipping issue should be resolved.

 

This is not to say that eventually a better mixing desk wouldn't be a good investment. The Behringer mixers are excellent value for money but, in terms of sound and longevity, aren't in the same league as things like Allen & Heath, Soundcraft and others in the next step up from there. I personally wouldn't recommend the Mackie. Although more money, they aren't much of a step up from the Behringer. However, when you get a new desk, do it for the right reasons...and curing feedback isn't one of them!

 

Bob

 

Thank you all very very much for the advice - It all makes perfect sense and I now feel confident that this will solve our problem. I'm going for the line out option into a DI box and the new desk idea is on hold for the time being so I can look at the options. The PA guy at a local dealer has just bought the Soundcraft desk which he is well impressed with so there's an option.

once again thank you very much.