this is the frequency response of a shure sm57, which i'm going to plug the altec in for instead (because it's less muddy on the bottom end, and brighter on the top):
looking at the graph, it's actually easy enough to understand why these mics sound like shit when recording distorted guitars - they roll-off before the fucking d string. all your power chords are getting attenuated - of course they sound like shit. like, is this a joke? it's not - i know it's not. but, it cuts around 150 hz, stays flat around the rest of the range of the guitar and rolls up after 3 khz (which is strictly the realm of harmonics, distortion, and effects, to a guitarist), then wobbles a little and crashes somewhere well beyond anything you can realistically hear as anything but noise.
this is the e906, which has three presence switches, and is quite similar but doesn't have those cuts at the top, as much:
watching reviews, i noticed that the e906 sounded less muddy and more clear than the sm57 and you can see why - it actually rolls the bass off even more, cutting the mud created by a putting the mic an inch from your amp out (you have to let low frequencies expand first, kids - otherwise you just get mud), and tweaking the presence so it's more relevant for guitar distortion frequencies. it's still flat over most of the spectrum of the guitar (although it starts a little later...), but it hones in the boost where a guitarist really wants it. so, the benefit of the e906 over the sm57 is that the e906 should sound sparklier at the top because it picks up more of the harmonic parts of the distortion - and it does. clearly. sort of. the 906 also has a presence cut that lets you flatten it out almost entirely. but, if you don't want that - if you want your guitar to sound like it's going to kill somebody's mom - then the shure is probably still the meaner, more evil option. you can scare your kids with it...
is that worthwhile to me? well, the 683b likely already does that for me, even if i can't find a frequency response. the mild difference in the 683b v the sm57 sounds like the difference in the above graphs.
so, i should not just stick with the 683b as an improvement over the sm57, but should hold to it as a primitive version of the same improvement made by sennheiser.
now, look at the 606 over the 906, though:
the 609 comes in far earlier - letting you decide if you want more bass or not by eqing it out later. it's more suited for a guitar, in that sense. further, those harmonic distortion frequencies peak high and fade more slowly than the 906, even opening up space for a frequency space that could only be occupied by feedback and hiss. this mic will pick up the good parts of your guitar tone and the bad parts of your guitar tone equally, and force you to deal with it in the mix stage.
i'm going to be recording with small amps that have small speakers and for that reason will produce more usable bass at closer ranges.
i'm going to wait for the marantz to get here and experiment a little, but i've decided that the 609 is the one i want, if i feel i need a better choice.
