Interesting Experiment - Air Brake & Tone
Jul 8, 2018 10:34:21 GMT -7
doctorice, BritInvasion, and 4 more like this
Post by GuitarZ on Jul 8, 2018 10:34:21 GMT -7
As I've mentioned in other threads, I hit a jam with friends where it's headphones only. I'm the only one making noise with my Ghia into my Air Brake on full bedroom max into my mic'd speaker. My sound has always had a 'fizziness' on the top end. I've adjusted the mic position, tried different speakers, etc, and it's gotten better, but basically still there. I always assumed it was how the amp was seeing the load from the Air Brake.
It dawned on me to replicate my set up here at home, record it, and then look at the frequency responses and such. I thought maybe I could EQ my way out. And, I've been messing with speaker IRs in my PC and thought it might help me figure out different mic positions that could help.
I was able to look at the differences via a spectral plot with a mic'd speaker. And, sure enough, as soon as I started to dial in the Air Brake, the EQ curve would change. Basically, the mids would start to drop. At a few clicks, it's not a big deal (and I've never felt a difference when playing live), but once I got to bedroom level and max bedroom level, the bass peak would shift from 165 Hz to about 142, with the curve dropping about 4-6 dB after, and then syncing up again with 0 attenuation at 2 kHz and above. The perception is a bass bump with more high end (fizziness).
While I was doing this, I tapped the signal after the Air Brake to run into my PC to use with the IRs. I figured they'd give me a bunch of different mics and positions such that I might find a combo that worked better on my real speaker. And, here's the interesting part. There really wasn't much of a difference with the IRs whether the Air Brake was set at 0 or Bedroom max. In other words, the Air Brake wasn't really doing anything to the amp's signal. It's as transparent as advertised.
It's how the speaker reacts depending on how much power it's seeing. Huh! This makes sense. I suppose I shouldn't have assumed that a speaker getting hit with my Ghia's fully wide open 18 watts would have the exact same response versus hitting the speaker with something much less than a 1 watt. I thought I'd share. Don't know if it's been looked at this way previously.
It dawned on me to replicate my set up here at home, record it, and then look at the frequency responses and such. I thought maybe I could EQ my way out. And, I've been messing with speaker IRs in my PC and thought it might help me figure out different mic positions that could help.
I was able to look at the differences via a spectral plot with a mic'd speaker. And, sure enough, as soon as I started to dial in the Air Brake, the EQ curve would change. Basically, the mids would start to drop. At a few clicks, it's not a big deal (and I've never felt a difference when playing live), but once I got to bedroom level and max bedroom level, the bass peak would shift from 165 Hz to about 142, with the curve dropping about 4-6 dB after, and then syncing up again with 0 attenuation at 2 kHz and above. The perception is a bass bump with more high end (fizziness).
While I was doing this, I tapped the signal after the Air Brake to run into my PC to use with the IRs. I figured they'd give me a bunch of different mics and positions such that I might find a combo that worked better on my real speaker. And, here's the interesting part. There really wasn't much of a difference with the IRs whether the Air Brake was set at 0 or Bedroom max. In other words, the Air Brake wasn't really doing anything to the amp's signal. It's as transparent as advertised.
It's how the speaker reacts depending on how much power it's seeing. Huh! This makes sense. I suppose I shouldn't have assumed that a speaker getting hit with my Ghia's fully wide open 18 watts would have the exact same response versus hitting the speaker with something much less than a 1 watt. I thought I'd share. Don't know if it's been looked at this way previously.