Control Over Phase? Little Labs I.B.P., part 1 of 2

I was seriously intrigued by the Little Labs I.B.P. hardware box when I first got to know about it many years ago. The fact that it could do something no other tool could got me excited in the first place. If I had one I could do something very special to my recordings. That was the point for me but to be honest little I knew about phase at that time.

These days I know more about phase and I’m thinking about it again: could it make it easier for me when recording? Maybe… Let’s listen and watch what Jonathan Little, I.B.P.’s dad, shows about it (up to minute 2’58”):

So I’ll consider the scenario proposed by Mr. Little: a direct, “pure”, not equalized signal coming from an electric instrument like a bass guitar is going straight to tape/D.A.W. through a D.I. box. By the way: the IBP itself (not the Jr. version though) is also a D.I. box with line level output that allows you to save a mic preamp for other tasks. Simultaneously, a second version of the same signal is linked from the D.I. box and injected into a bass amp like an Ampeg SVT (not SBT!), it is therefore picked-up by a microphone placed in front of the speaker and sent to tape/D.A.W. as well. According to Mr. Little, the applied eq on the head and the speaker cabinet itself affect and modify the phase of the second signal. “Everything has a phase versus frequency response“.

Mmmhhh… I think what really matters here is that the second path is such a different one to actually cause a time offset between the two signals! The direct signal gets recorded before the amp+microphone signal and this situation creates phase issues. It is true that everything has a phase vs. frequency response, but the point here is the difference between differences: you would not get any issue if you were to use just the D.I. track or just the mic’ed cab track. Said difference is the one generating issues and it should be clear by now, after reading previous posts, that issues manifest only at certain frequencies. Let’s not forget that!!! Each out-of-phase combination has a different (more or less negative) phase result for specific frequencies, depending on their period. One specific out-of-phase combination is also more or less positive (additive) for specific frequencies: the most positive happens when the difference in time between the two signals corresponds to the period of that frequency.

Let’s say we can measure the delay between the D.I. signal and the mic+amp signal: 4,31 ms. That’s the period of 232 Hz: said frequency is perfectly tuned, actually reinforced by the so-called “phase issue”. Major problems though for 116 Hz: totally canceled out! If you’ve read the previous posts you should understand why. No wonder then when Mr. Little goes “more in depth” analyzing ONLY ONE frequency, 400 Hz showing on his oscilloscope. With the I.B.P., as with any other tool or method, you can only tune one fundamental frequency at a time!!!.

When you have two microphone like say a room mike and you have a mike on the kick drum or a tom-tom for istance, you’re gonna get a degree of cancellation between the two. As you can see… (fiddling with the knob) this is just like moving the mike: you can see that it’s gonna cancel the signal somewhat. Remind that we’re looking at a sine wave (!!!), not a complex music wave. I’m using the simplest form to explain this (???)”.

In fact Mr. Little that is fiddling with 400 Hz ONLY. WHAT IS GOING ON WITH ALL OTHER FREQUENCIES? Variably in/out of phase…

My personal conclusion is that the I.B.P. box could be helpful in trying to tune (i.e. get perfect phase) two signals at one specific frequency without my usual need to track in advance to the recorder. It doesn’t provide though any information about the frequency itself and therefore I’d still have to set up a more elaborate way to target it.

3 thoughts on “Control Over Phase? Little Labs I.B.P., part 1 of 2

  1. What it seems to me, the IBP is just an adjustable delay unit.
    Maybe a more “comfortable” way to go than moving microphones?
    Probably yes, but we can also just do it in protools with DLA… and its free!

    1. Hi Michele! ;-)
      I would not look at the IBP as an adjustable-delay unit.
      Sure phase is about time, but watching the video you can see that upon turning the knob, the top sine wave is anticipated in time rather than delayed. This is the IBP doing its job: I have no idea how this can happen but I see it happening and I take it.
      I don’t know what you mean with DLA: is that a plugin delay?
      Also consider that we are talking about tuning microphones at specific frequencies here.
      You might NOT WANT to move microphones because you like their individual sounds where they are positioned, but when you combine them you get phase issues. And then IBP could be really comfortable if you have a proper set up to check mic tuning prior to press the record button. Lacking that, you’d have to check it after recording and at that point you don’t necessarily need an IBP. You follow me?
      Thank you for your message, please share your experience.
      Take care, G.

      1. Hey Michele, it’s been a while but I thought I’d correct myself after testing in depth the unit: it is indeed a delay unit as you were suggesting. The weird/cool thing is that it doesn’t delay all frequencies by the same amount! So it is NOT like delaying the tracks with a plug-in. Please check my new post for a more accurate explanation (at least I hope so!) and test.

        Take care, G.

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