I've always had better results with using a DI than with micing my cabs, but I often had to do a lot to make the DI sound the way I think my bass should - so I wanted to test out some different mic options...
For the first attempt at my test, I taped off a square on my speaker grille so that I’d be putting the mics in the same spot, then I recorded a sample with each mic.
There were clear differences – but between different volume levels and different performances, there were too many variables to be able to conclusively say what made the difference.
So for my next attempt, I set out to remove the variables:
I wanted to have the same performance every time, so I played into a looper to ensure that what I recorded each time was exactly the same.
Knowing that our ears tend to trick us into preferring louder sounds, I wanted a way to gain-match, so I used a signal generator to play a few seconds of a sine wave at 120 Hz into my looper before I started playing my bass.
(I picked 120 Hz because I wanted it in the bass range, but any lower and you start getting into the range where the mics or cabinets might start rolling off).
Once I had the loop recorded, I was able to record all the various mics in the exact same spot with the exact same performance.
Then, I could see which performance was the loudest and use the sine wave portion to see what dB level output that represented. (In my case, the loudest sine was -16.2dB)
So then I looked at each sample, and adjusted the waveform to make the sine portion of the sample measure -16.2dB -- if the sine was -20dB, I added 3.8dB of gain, etc...
Once all of the samples were the same volume, I cut off the sine portion, set my DAW to loop the recordings, and listened to each channel individually.
That led me to a pretty clear favorite mic (a discontinued Peavey PVM mic that I've had for about 20 years).
With my preferred mic identified, I used my sine + bass loop again to try out different positions – edge of the cone, middle of the cone, cone/dustcap junction, and dead center.
Again, I gain-matched all of those.
I liked dead center the best – it seemed most “true” to how the cabinet sounds in the room.
With my preferred mic and position identified, I tried out different distances – right at the grille, 6” back, 12” back, and 24” back.
Again, I used my sine + bass loop, then gain-matched.
My preferred distance was 6” – it opened up and sounded more “real” than right on top of the grille, but then when I went to the larger distances, they started to sound a little “diluted”.
Once I'd pulled back from the cabinet a bit, it occurred to me that it had become less crucial which part of the driver I was pointing at.
That made me think: part of the reason I have always skipped putting a mic on my cabs is because they are 2-way cabs, and close-mic’ing them wouldn’t be an accurate representation. But if I like the sound best from 6” back, why not mic between the low and high frequency drivers?
So I tried that, and the recorded sound was pretty much exactly what I’m hearing in the room. I recorded the loop with each of my amp heads and cabinets. That told me which combination mics up the best, but again all of the samples sounded like what I was hearing in the room.
Comparing that mic'ed amp sound to the same loop recorded via my DI (Warm Audio passive with a CineMag transformer) was like comparing steak to vanilla ice cream.
But there were plenty of mic choices and mic positions that were vastly inferior to the DI - and I would have stopped trying if I hadn't "gone down the rabbit hole" to test out all of these different variables.
For the first attempt at my test, I taped off a square on my speaker grille so that I’d be putting the mics in the same spot, then I recorded a sample with each mic.
There were clear differences – but between different volume levels and different performances, there were too many variables to be able to conclusively say what made the difference.
So for my next attempt, I set out to remove the variables:
I wanted to have the same performance every time, so I played into a looper to ensure that what I recorded each time was exactly the same.
Knowing that our ears tend to trick us into preferring louder sounds, I wanted a way to gain-match, so I used a signal generator to play a few seconds of a sine wave at 120 Hz into my looper before I started playing my bass.
(I picked 120 Hz because I wanted it in the bass range, but any lower and you start getting into the range where the mics or cabinets might start rolling off).
Once I had the loop recorded, I was able to record all the various mics in the exact same spot with the exact same performance.
Then, I could see which performance was the loudest and use the sine wave portion to see what dB level output that represented. (In my case, the loudest sine was -16.2dB)
So then I looked at each sample, and adjusted the waveform to make the sine portion of the sample measure -16.2dB -- if the sine was -20dB, I added 3.8dB of gain, etc...
Once all of the samples were the same volume, I cut off the sine portion, set my DAW to loop the recordings, and listened to each channel individually.
That led me to a pretty clear favorite mic (a discontinued Peavey PVM mic that I've had for about 20 years).
With my preferred mic identified, I used my sine + bass loop again to try out different positions – edge of the cone, middle of the cone, cone/dustcap junction, and dead center.
Again, I gain-matched all of those.
I liked dead center the best – it seemed most “true” to how the cabinet sounds in the room.
With my preferred mic and position identified, I tried out different distances – right at the grille, 6” back, 12” back, and 24” back.
Again, I used my sine + bass loop, then gain-matched.
My preferred distance was 6” – it opened up and sounded more “real” than right on top of the grille, but then when I went to the larger distances, they started to sound a little “diluted”.
Once I'd pulled back from the cabinet a bit, it occurred to me that it had become less crucial which part of the driver I was pointing at.
That made me think: part of the reason I have always skipped putting a mic on my cabs is because they are 2-way cabs, and close-mic’ing them wouldn’t be an accurate representation. But if I like the sound best from 6” back, why not mic between the low and high frequency drivers?
So I tried that, and the recorded sound was pretty much exactly what I’m hearing in the room. I recorded the loop with each of my amp heads and cabinets. That told me which combination mics up the best, but again all of the samples sounded like what I was hearing in the room.
Comparing that mic'ed amp sound to the same loop recorded via my DI (Warm Audio passive with a CineMag transformer) was like comparing steak to vanilla ice cream.
But there were plenty of mic choices and mic positions that were vastly inferior to the DI - and I would have stopped trying if I hadn't "gone down the rabbit hole" to test out all of these different variables.
