Using 2 or More Mics for the Guitar Amp Speaker(s), Part 6
This article is the second installment on using a mic on the guitar amp (close-miked as usual) and one or more room mics. It's most important to review article #21 for miking details, etc. We will now dial in the sound on the mixer.
Signal Path For Two Mics to Two Recorder Tracks
This is different from the routing we have been using in previous articles. If you are using more than one close mic, refer to Parts 14 through 20.
Set your levels as discussed in previous parts of this series. For our example, we are recording the guitar on recorder tracks #7 and #8 and using mixer modules #9 and #10 for the two guitar mic inputs. Let's use mixer module #9 for the close mic and mixer module #10 for the room mic. If you're using a digital recorder with a built in mixer, simply adapt with the same layout.
1. Plug one guitar amp mic cable into mixer module #9s mic input.
2. Plug the other guitar amp mic cable into mixer module #10s mic input.
3. On mixer modules #9 and #10, to start, set the mic pre amp trim to 20 dB. (If you have only one input gain trim pot per mixer module, that is used for both source line input gain and mic input gain. If you're using a computer hard disk recorder with outboard analog to digital inputs, use the same setting on the input level control to start).
4. Assign mixer module #9 to bus #7 (bus #7 routes to the recorder track we are using for the close mic). Note that if mixer module #9 has a direct output, instead of using bus #7, patch the direct output into recorder track #7s input. Make sure that module #9 is not sent through the monitor chain and is only routed (bussed) or patched directly into record track #7. Mute this module for now.
5. Assign mixer module #10 to bus #8 (bus #8 routes to the recorder track we are using for the room mic). Note that if mixer module #10 has a direct output, instead of using bus #8, patch the direct output into recorder track #8s input. Make sure that module #10 is not sent through the monitor chain and is only routed (bussed) or patched directly into record track #8. Mute this module for now.
6. Set recorder tracks #7 and #8 into input mode so we can monitor the guitar signal through the recorder, which routes to mixer modules #7and #8. (In digital land, you may want to monitor the mic-input signal on modules #9 and #10 BUT only do so if you notice a delay when monitoring through the digital mixer and or recorder path. I will get into this subject in future articles).
7. Bring up the studio control room monitor level up to a normal listening level.
8. Mixer module #9 level settings: Bring up module #7 (recorder track return) about half way up on the fader throw. Ask the guitarist to play the part for the song. While the guitarist is playing, un-mute mixer module #9 and slowly bring up the fader to zero (unity gain).
8a. If using an analog mixer and recorder set the mic pre-amp trim level on the mixer to average zero dB on the recorder track meter for now. For now, mute mixer module #9.
8b. If using a digital recorder format, adjust the mic pre-amp trim level to -4 dB on the recorder track meter for now, a safe spot in case the guitarist plays louder when recording. You dont want to distort in digital. For now, mute mixer module #9.
9. Mixer module #10 level settings: Bring up module #8 (recorder track return) about half way up on the fader throw. Ask the guitarist to play the part for the song. While the guitarist is playing, un-mute mixer module #10 and slowly bring up the fader to zero (unity gain).
9a. If using an analog mixer and recorder adjust the mic pre-amp trim level on the mixer to average zero dB on the recorder track meter for now. For now, mute mixer module #9.
9b. If using a digital recorder format, adjust the mic pre-amp trim level to -4 dB on the recorder track meter for now. For now, mute mixer module #9.
Monitor Panning: In this case, you may want to pan the close mic and room mic slightly off center or possibly very wide to full left and right. No matter the pan position settings, it will be an attention getter since the sound is very different. If you don't want major attention and or want to save sonic space, pan both the close and room mic to the same spot in the pan spectrum.
Note that if you want to use a third mic (or more), simply follow all of the above instructions using another mixer module and another recorder track. By now, you surely have the procedure down. Regarding panning for two room mics, the logical thing to do would be to pan left and right with the close mic panned center but there are no rules as usual so experiment.
I did not mention recording the close and room mic to one track. If you need to do so, by now, you surely know the drill. Be careful here since the blend is obviously final. It's important to get a good band mix set to see how much room mic should be added.
EQ Settings: EQ both mics separately. Refer to the articles on EQ per the close mic application (Parts 4 through 9). Mute mixer module #10 and un-mute mixer module #9. EQ the signal on mixer module #9 to taste. When you are happy with the EQ settings, mute mixer module #9 and un-mute mixer module #10. Now we have EQ considerations for the room mic so here we go. Remember in all of the following stuff after this EQ section, you may want to tweak the EQ on both mixer modules #9 and #10 after achieving a good monitor mix of all instruments.
EQ for Room Mics
The following mostly relates to low buzz saw 5ths or distortion guitar sounds in general but also applies to clean sounds, if the clean sound is loud setting the room off in major reflections.
Low frequency filter: Typically a very steep filter that eliminates low frequency information. If the guitar amp is being recorded in a room with other instruments (such as bass and drums) and there is low frequency leakage from other instruments into the mic (the odds are good this will happen in this case), its best to use the low frequency filter to get rid of room rumble. The filter may be frequency adjustable or a fixed frequency. If its adjustable, experiment with the frequency settings to find which works best.
30 to 80 cycles: If the guitar amp is isolated in a room with no other instruments, if recording a rock power trio, and the room does not have big low-end build ups, try adding a few dB at 80. Be careful here since you may smear out the bass in the overall mix. If you do this, in most cases, you will need to compress big time.
If the guitar amp is in the same room as other instruments like the drums, I would not add here and maybe roll out a few dB at around 50 to 80 cycles if the low frequency filter did not get rid of the low end rumble. It's difficult to know what is happening in your room since we are not there at the moment but the idea is to avoid room rumble, especially if it is getting in the way of the bass or is just low-end garbage. No rules friends, just food for thought.
If the room is not creating low-end information, remember that adding EQ is gain addition so adding in an area that really does not effect the sound will be adding level to the overall gain path. This will take away some headroom area when mixing.
80 to 200 cycles: Same as the above if you have rumble problems. If the room is friendly in this area, try adding at 100 if adding at 80 did not work. Again, every room will react totally different. Mic placement will also be so very important. This area will typically be a slight roll out if rumble problems.
200 to 300 cycles: More possible room garbage. Again, experiment. Typically, this area may need a slight suck out if the 80 to 200 did not fix the rumble.
300 to 600 cycles: This area is getting near the meat of the room sound. Most likely, if there is not a major sonic fight with keyboards, no need to do anything. Again, all rooms sound totally different so check to see if you need a slight roll out or addition.
600 to 800 cycles: This is typically the main part of the room sound. Add if you want it boxy or pull back if not wanting the mids. A single dB usually goes a long way in this area since it is the meat of the sound.
800 to 1 kHz: This relates to the above and below depending on the room frequency peaks.
1K to 2 kHz: This area really opens up the sound. Around 2 kHz may be a good place to add if wanting to get apparent level and note definition. Unless recording in a cement room, adding here should not cause ear pain. On the other hand, if the addition is casing ear pain at a medium monitor level, pass and add in the next area below (if needed).
2 kHz to 3.5 kHz: This area also opens up the sound. Try adding around 3 kHz if the 2 kHz area was painful or did not sound as good as the addition here. If painful, pass. If not, this will help definition. Watch out that adding here does not make the guitar sound cheap (unless that is the sound you are looking for), especially if using distortion.
3.5 kHz to 5K: This area usually starts bringing up the sparkle but not in this case, unless the room is cement or plaster or really live. You might like adding a few dB as long as it actually does something friendly to the sound.
5 kHz to 8 kHz: Same as the above.
8 kHz to 12 kHz: When adding here, using the frequency sweep technique (explained in Part 4 Tracking Clean Rhythm Sounds), try to find a spot that adds air without sounding tizzy. You may find a spot that works.
NEGATIVE EQ: In most cases, this concept will really small up the room sound which may be desirable if there are way too many frequency pockets. Look for these but keep in mind that the places where you find them will typically be the meat of the sound so slightly roll out unless you are looking for an extremely effected sound.
That brings up another issue. Since there are no sonic rules, if you're looking for a strange sound, you will surely find that the room mic(s) will give you just that, so go crazy with the EQ pots and you will create weird ambience EQ pockets stuff that may be the next new sound!
Adding the Compressor: Refer to the articles on compressors (Parts 10 through 13). The compressor will surely affect the room sound since it is a soft signal (no hard attack transients on account of reflections and air diffusion). If you want to make the room sound aggressive, slam it with compression! A fast attack, a 10 to 1 ratio and about 10 dB of compression should do the trick. Using a mid release time might be good so the compressor does not pump too hard. No rules so twist those knobs (or software knobs)!!!!
The Blend: Keep in mind that we are recording to two separate recorder tracks so the blend is a simple monitor blend that is not permanent.
To set the blend; pull down both mixer module #7 and #8 faders to the bottom of their throws. Make sure both mixer module #9 and #10 are un-muted. While the guitarist is playing (as always when dealing with electronic settings), slowly bring up both faders and experiment with different level settings to achieve a good blend. When needing to change the overall guitar monitor level when listening to the full band, simply move mixer module #7 and #8 faders together keeping the same relative levels. If you have mixer automation, group them together so one fader moves both, or assign them to a separate group fader.