Speakers and microphones

Microphones

Impulse responses are captured using microphones and mic preamps.

"Using a "neutral" IR with a simulated mic does not sound the same as an IR using that mic. It simply can't. Neutral mics like the Earthworks TC series are nearly omnidirectional. They operate by using a very small aperture as compared to traditional mics that have effective apertures orders of magnitude bigger." [1]

"The mic I've been most impressed with for recording guitar lately is the Beyer M160. I don't like SM57's alone for amps. They're too spikey and compressed but mixed with an M160 or R121 they add some nice sizzle." [2]

"The M160 is an awesome guitar cab mic. All the IRs we got with the M160 came out really nice." [3]

"My typical workflow is to choose an R121 or M160 first as these have the best low end. Then I choose an IR from one of the other mic types to get the desired brilliance. This is usually an SM57 or 4047. I just don't like 906s or 414s but that's me. I leave the panning at default but that's just my preference." [4]

"If you get a chance try a Shure KSM313, an AEA R84 and a Beyer M160. The KSM313 is now my preferred mic for guitar cabs. I like it better than the R121. I find the KSM313 a little more balanced. The R121 has a lot of bass and proximity effect and the high end can be a little dull." [5]

"My favorite mic for guitar cabs is the KSM313." [6]

"Certain mics like the royer 121 have 2 sides (front, back). Each has a different sound. Back side of the R121 is a bit darker. The difference between the front in the back is only apparent at closer mic distances. Get out past 3 feet and the sound the same on either side."

"The M160 is a good mic but there are better ribbon mics. My personal favorite is the KSM313. It's more balanced and has better high frequency response. I haven't tried the KSM353 yet but I imagine it's even better. [7]

"IMHO nothing beats a KSM313 for "neutral" close mic'd IRs." [8]

Dialing in Your Tone by Red Wirez provides useful info about mics and mic positioning.

Wikipedia:

• Shure SM57
• Shure SM58
• Shure Beta 87A
• Neumann U87
• Royer R-121
• AKG D112
• Neumann U67

Additional information about microphones:

• http://www.soundandrecording.de/tutorials/mikrofonvergleich-vor-dem-e-gitarrenverstaerker
• Wikipedia
• http://soundschematic.com/dynamic-ribbon-condensor
• http://www.barryrudolph.com/stellar/guitar.html
• http://www.gearslutz.com/board/so-much-gear-so-little-time/201972-mic-standards.html
• U67
• SM57
• SM58
• MD421
• U87
• D112
• Beyer M160, Beyer M160
• Sweetwater: Guitar Cabinet Mic Shootout – with Sound Samples
• The Importance of Mic Placement for Guitar Amps – with Sound Samples
• What's the difference between Shure SM57 and SM7b

From "The SOS Guide to Live Sound" by Paul White:

Guitar speakers

Impulse responses reproduce the sound of a speaker cabinet. Here's some background information on guitar speakers.

• Speakers: the final frontier
• Legendary Tones: G12M versus G12H
• Sound On Sound: choosing guitar-amp speakers
• Sound on Sound: understanding and recording guitar speakers
• Eminence tone guide
• Fenderguru: selecting speakers
• Celestion history
• Pre-Rola greenbacks explained, part 1
• Pre-Rola greenbacks explained, part 2
• Premier Guitar: how a speaker cabinet influences your tone
• Sound clips of Celestion speakers on SoundCloud

Jensen speakers:

• P12R: 12” 15W
• P12Q: 12” 20W
• P12N: 12” 30W
• P10R: 12” 15W

"Break-in is definitely real with guitar speakers. The surround is stiff when new due to the doping. I don’t think monitors and hifi speakers exhibit any significant break-in." [9]

"We witnessed speaker break-in first-hand when shooting IRs. We bought a brand-new 5150 III cabinet. Went to shoot some IRs and they sounded terrible. So I put the synth block on and ran the speaker for several hours while we were doing other stuff. Came back and shot some IRs and they were much better sounding." [10]

How a speaker works: electricity runs through the voice coil (wire), creating an electomagnetic polarity that shifts depending on the input signal. This makes the coil move closer or away fom the magnet.

Ohm = AC Resistance (not: AC current) = impedance. Adding speakers in series increases resistance, adding speakers in parallel decreases resistance. Examples:

• 2 identical speakers wired in parallel: combined impedance is half that of the individual speaker (2 x 8 ohm = 4 ohm)
• 2 identical speakers wired in series: combined impedance is doubled (2 x 8 ohm = 16 ohm)

From "The SOS Guide to Live Sound" by Paul White: