Shaping Guitar Tones

The No More Source Of Confusion series goes on…

Upon checking some video stuff online, I noticed a recent contribution by guitar great Tim Pierce. I’ve watched videos from his “Tim Piece Guitar” channel before and it’s always cool, top notch, very inspiring material. This is to say that my post is not meant in any way to diminish the content of Mr. Pierce’s video. He’s great, his gear is awesome and his tone is superb. My post is just about a couple of spots which, from my personal point of view as a “phase issues devoted”, stand out as relevant. Because the subtitle to the video goes like “on shaping guitar tones with an R-122V and an SM57”, I thought some aspects should be magnified to the eyes and ears of an audio engineer to improve his/her skills when working to shape a guitar tone and using two microphones. Hopefully Mr. Pierce will appreciate this too.

The graphics introduced at the beginning make clear how Mr Pierce’s signal is engineered from speakers cabinet to recorder: SM57 into BAE 1028 preamp, R-122V into Skibbe Electronics 736-5 both going to ProTools DAW. What is not mentioned is where Pierce has hooked up the Chandler Limited Mini Rack Mixer (line only mixer, not shown in the graphics) used to create a balance between the two paths. Presumably before Protools inputs? That would allow him to create the desired blend and commit to it. It looks like the channels he works on the mixer are both panned left, actually suggesting a two-channels-into-one-track configuration. This doesn’t matter much but I thought I’d highlight it for anyone wondering about the little red knobs he is rotating.

Mr. Pierce starts with a guitar equipped with P90s pickups, looking for a “clean” tone. He declares he is using only the Royer R-122V at first: he likes the settings but still is curious to investigate the contribution of the SM57. At 4’02 he dials in the 57 and the sounds gets, in his own words, “nosey”. Well… here’s the first relevant spot I was talking about: the nose is clearly a comb filtering effect. It’s not that the 57 is a nosey microphone or it adds “nose” by itself. It is the combination of the two, the 57 and the R-122V that sounds nosey because portions of the frequency spectrum are canceled while at the same time other portions are boosted. The resulting frequency response is contaminated by inevitable comb filtering. The 57 shouldn’t be blamed. This is confirmed at the second spot, around 6’15”, when “coming from the other direction” Pierce goes for a different part with a different, brighter guitar (G&L ASAT) and starts off with the SM57 only. Not “nosey” at all on its own, don’t you think? He’s actually very surprised when he adds the Royer, not expecting all that midrange (lower midrange I would say) build up… which is exactly what happened before: the “nose” again, affirming the fact that his R-122V and SM57 in that specific position in front of the speaker (check out 1’18”, note the two are not perfectly aligned in height) they just combine in that specific way, creating that specific filtering. What is most evident is a build up around 120 Hz, roughly, suggesting that the two microphones are possibly in tune at one fundamental frequency around that area and “out of tune” in the higher range of spectrum.

Speaking of guitar tone shaping, I know by experience that there’s only so much you can obtain leaving things like that: you start with one mic, add the second one, mix the two with different proportions and hope you like the results. If you like it and it works for you, that’s cool. But the shaping can definitely benefit from some refinements.

Refinement #01: move one of the two microphones away from the speaker… There is a very good chance that the comb filtering will shift to a higher range of the spectrum, opening up the tone of the mic combination. Don’t wanna do that ’cause you like the tone of each single microphone in its position? And most of all, you don’t want to move a mic every time you are searching for the right tone? Understandable… Refinement #02: leave the mics where they are and apply a few ms of delay (start with 1 ms) to one of them: a coarse resolution but it gives you options… Refinement #03: leave the mics where they are and get a phase alignment tool, hardware or software, apply it to one of the two microphones and by gradually working the tool, you’ll move the mic without actually touching it! You will be able to tune the microphones at different fundamentals and finally get the right proportion for the right tone.

P.S. If you have read the previous posts, you already know that a dynamic (moving coil) mic + a ribbon mic is quite a different situation than a dynamic + condenser mic.

Thank you very much. And thanks to Mr. Tim Pierce!

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