Bringing the backline back in line

Posted by admin on August 4, 2012

There are some great amps and cabs out there, from a blasting orange amp to a vintage Marshall stack. As a sound engineer whose job it is to reinforce the sound, do you really need to mic it up? OK, in some situations it's quicker and easier to just turn the amps up. But being honest, if you have the facilities (mics, channels, time etc) then I'd be miking them up.

Why I hear you ask?

  • Better level control 
    You're able to balance the volume of the lead guitar to the bass guitar and the overall output level, it's a bit tricky having to run on stage and tell the guitarist to boost his amp or drop it down mid-show!
  • Able to shape the sound
    If there's a particular frequency on the electric guitar that's ringing or there's too much treble carrying over a long distance, you're able to boost the mids. This will change a lot during each song so you're able to quickly and easily alter it 
  • Much easier to make changes
    No brainer really, reaching for the EQ dials or running to each individual amp and then back to see the difference. Or if you have a digital desk then using your wireless iPad... ;-)
  • Reduce bleed to other mics
    If you can get them to turn their amp down and use the mic to boost it louder at FOH, then less will hit the vocal mics, reducing your likelihood of feedback
  • Quickly adapt to the change in sounds
    I've used 2 mics on a Marshall cab before during a live situation, one positioned to grab the highs and one for the punchier lows, and listened during the band's songs and blended the mics depending on what the guitarist was aiming for. This way you're able to get more of a reinforced sound than just a loud amp that sits quite far from the audience at the back where some frequencies may get lost. 

But be warned: you can do it wrong. I've heard a story of one engineer sticking several mics on the head of an amp stack, not a cab, then complaining that he's not getting great levels through.... (for those of you too scared to ask, a head is the amp that sits on top with the dials on, the cab is the speaker cabinet where noise comes out of...).

Another problem is convincing the musicians to get on board. I've been to places where the musicians are adamant their acoustic guitar needs to go through a mini PA speaker system, which is then miked up! Ultimately, there are two ways to grab the sound of the backline:

1) DI'ing

This is the method I'd go to first for acoustic guitars (with pickups in), bass guitars (unless they've got a particularly nice amp) and possibly to just give yourself an extra option at the desk end of a clean feed that is much less likely to feedback.

DI Link Output diagram

Most DI boxes have a 'LINK' output that will enable the musician to still have a feed to their amp but for you to take a clean feed to the desk.

Essentially, you go from instrument -> input, then balanced out -> desk, and link out -> amp (see diagram). This can be a cost effective way of providing the musician with their own monitor mix, but really I'd try and steer them towards losing the amp.








2) Mic that amp up!

There are tons of different mics you could use in a million different places. Here's a quick handy guide to where to position them...

Labelled Marshall with mic positions

> If you move the mic towards the speaker, you tend to get more bass response (and obviously a louder input signal, so can get more headroom from it). Away from the cab, less low frequencies (LF) but it may increase your chances of feedback.

> Move the mic closer to the centre of the cone (sometimes you have to look carefully behind the mesh to find the cone size) and you get a cleaner, brighter sound; move towards edge and you get a more subdued, duller sound. Somewhere in the middle and you get a blend.

Really you're looking for the 'sweet spot' - some musicians may know where this is on their amp but most probably don't. Mic wise, really it's up to you: you can get some mics that are designed to be hung over the top of the stack and dangle on the cable (eg the E906). I stick by a good SM57 for most applications, often found in many studios. If you've got a good quality condenser to spare, give it a go: may sound wonderful but it really depends on a lot of factors- the amp, guitar, desk, FOH speakers, band etc.

Also bear in mind that if you manage to get the musicians to bring their amp volume down it may be wise to send some back through the monitors for them (as much as they like if they're on IEMs).

Sometimes you have to strike a compromise. While engineering a band, I had to accept that the lead guitarist had to crank his amp in order to hear himself as he went around stage. Ideally IEMs would have solved the issue, but lack of kit and time meant it was easier to strike the balance and let him crank it. Keep the musicians happy and you'll get hired again! ;)

That's all for now folks!


Leave a Reply

(Your email will not be publicly displayed.)

Captcha Code

Click the image to see another captcha.