For recording electric guitars, I've been doing a "trick"
using the figure-of-eight Royer R121 ribbon microphone.
I like this method because it increases the "coupling"
of the low-end frequencies and air of the speakers to the
mic. I find it great for loud clean sounds and cruncher rhythm
parts especially low-tuned guitar parts where you want as
much "sturm und drang" as possible.
I line up two, 4 x 12 Marshall cabinets directly facing each
other as close as six inches. I put the Royer in between the
two cabs in the exact middle so that each lobe is aimed at
an opposing cabinet. The two lobes of the figure-of-eight
pattern are 180 degrees out of phase from each other.
The big trick is that you have to flip the polarity of one
of the speaker cabinets so it is out of phase with the normally
wired cabinet. To get these two cabinets to "push-pull"
together, I made a foot-long jumper cable with a female 1/4-in
jack at one end and a regular male 1/4-in plug at the other.
Just solder the tip of the female to the sleeve of the male
and the tip of the male to the sleeve of the female. It's
a polarity flipper!
Both cabinets must be connected to the same head
100-watt Marshall tops. It's important not to use two amps
because there might be a phase flip (between them) other than
180 degrees. You should investigate if the polarities of the
speakers inside the cabinets are all the same.
Some manufacturers intentionally flip the polarity of the
individual speakers to get a particular overall sound character
from the cabinet. If that is the case and you don't want to rewire them, figure out
which speaker are wired the same way in both cabinets and mic them
as a pair with the Royer.
You can get a lot of different guitar sounds, by varying how close
the speaker cabinet are to each other, where you put the mic, and
which pair of speakers you mic. For example, for a bright sound,
you can put the mic equidistant and in the exact center of two speaker
pairs. If you want more of an overall cabinet sound, pull the cabs
further apart and place the mic vertically and horizontally in the
Lastly, check for equal level from each speaker by having an assistant
(he may want to wear ear protection) unplug, one at a time, each
cabinet while your guitarist plays. In 1/2-in increments, move the
Royer closer to the softer cab. Try rotating the mic, as there is
a difference in sensitivity from one side to the other. Every time
I have suggested it, guitar players love playing using this rig!