The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Gear for sale  Search Gearslutz Go Advanced
Phase compensation between pickups. Direct Injection & Re-amp Boxes
Old 26th September 2013
  #1
Gear Maniac
 

Phase compensation between pickups.

So, the other day I'm tracking my Ric bass. Being indecisive, I decide to make use of the stereo out and record each pickup individually so I can fool with the mix later. Now naturally, the pickups are slightly out of phase with one another. That fine, just physics right? But on a lark, I shifted one track into phase with the other and bam! There it was, the sound! So cool, nice trick in the daw world but can I do this live?

I gather the little labs ibp works along these lines but I can't put that in a pedal board right? I am thinking a stomp box phaser that is all wet signal? I dunno... Is someone ahead of me on this?
Old 26th September 2013
  #2
Lives for gear
A phaser is a cool idea, but I don't think it'll do what you want. Not only does each pair of poles only put the signal 90 degrees out of phase, but the "sweep" is moving the crossover between phased signal and actual signal. I think Radial makes a phase box for their 500 series but that's worse than the LL. I'd mount the LL under the pedalboard if I wanted that effect...
Old 26th September 2013
  #3
Gear Guru
 

I think the stomp box phaser would just oscillate the phase in and out continually.


The regular IBP (not the Jr) is also a reamper, so it has instrument level in and out. I believe this goes through the phase shifter, but I have never tried to use it this way.
Old 27th September 2013
  #4
Lives for gear
Quote:
Originally Posted by joeq View Post
I think the stomp box phaser would just oscillate the phase in and out continually.


The regular IBP (not the Jr) is also a reamper, so it has instrument level in and out. I believe this goes through the phase shifter, but I have never tried to use it this way.
There are stompboxes (like the Pigtronix) where you can stop the phase, it's designed to be used as an envelope phaser, but set with the sensitivity high enough would be open all the time. But, again, you'd only have the ability to change the phase by 90 or 135 degrees (can't remember if it's a 4 or 6 stage phaser).
Old 27th September 2013
  #5
Lives for gear
 
pinkheadedbug's Avatar
 

Why would the pickups be out of phase with each other? The phase of a string vibrating at its fundamental is the same along its length. Only the amplitude changes.

Sure the harmonics are going to be out of phase but if you put them in phase you put the fundamental out of phase.
Old 27th September 2013
  #6
Gear Guru
 

Quote:
Originally Posted by pinkheadedbug
The phase of a string vibrating at its fundamental is the same along its length. Only the amplitude changes. Sure the harmonics are going to be out of phase but if you put them in phase you put the fundamental out of phase.
Good point. Some guitarists I know have switches installed to deliberately put a pickup out of phase.

It sounds kind of cool, but, when engaged, it always sounds "OUT" of phase, even when the pickups are the neck pickup and the bridge pickup.

It also should be pointed out that time-shifting a track in the DAW is not the same thing as rotating phase with something like the IBP
Old 27th September 2013
  #7
Don't confuse "phase" with "polarity".
Old 27th September 2013
  #8
Lives for gear
 

Quote:
Originally Posted by F.M. View Post
So, the other day I'm tracking my Ric bass. Being indecisive, I decide to make use of the stereo out and record each pickup individually so I can fool with the mix later. Now naturally, the pickups are slightly out of phase with one another. That fine, just physics right? But on a lark, I shifted one track into phase with the other and bam! There it was, the sound! So cool, nice trick in the daw world but can I do this live?

I gather the little labs ibp works along these lines but I can't put that in a pedal board right? I am thinking a stomp box phaser that is all wet signal? I dunno... Is someone ahead of me on this?
you can just put a delay on one of the pickups, this is a 4001 with stereo out?
so just run one output through a 5ms delay or whatever it is.
You will know they exact number by looking in your DAW and whatever you nudged it

how much are they out of phase?
Old 27th September 2013
  #9
Gear Maniac
 

You might be right about this being a harmonic rather than phase issue. But visually, in the daw it looks like two mics a hair out of phase. The notes start at the same time but the waveforms don't agree. By perhaps 20 degrees more or less.

Flipping phase (as with the phase switches found on some guitars) is much to heavy handed to address what I'm talking about. And would lack the fine control that would make a useful stomp box. A millisecond delay is about right but I have the feeling that that's too course. A microsecond delay seems like what I want.
Old 27th September 2013
  #10
Sounds like the IBP is what you want. And I see no reason it can't be put on a pedal board.
Old 28th September 2013
  #11
Lives for gear
 

Quote:
Originally Posted by F.M. View Post
You might be right about this being a harmonic rather than phase issue. But visually, in the daw it looks like two mics a hair out of phase. The notes start at the same time but the waveforms don't agree. By perhaps 20 degrees more or less.
The sound of a guitar/bass with both pickups on and slightly out of phase is however accepted since all guitars are this way. 20° degrees at 500hz is .1 ms. Can you even hear that?

But harmonics can be calculated based on neck scale and pickup location
Roman was a little eccentric but here is a great article on what you are talking about

Tech Articles - Scale Lenght Argument Settled once and for all!!

Quote:
Originally Posted by F.M. View Post
Flipping phase (as with the phase switches found on some guitars) is much to heavy handed to address what I'm talking about. And would lack the fine control that would make a useful stomp box. A millisecond delay is about right but I have the feeling that that's too course. A microsecond delay seems like what I want.
Yeah wiring and flipping a phase switch is not going to work. If you wire two pickups out of phase as in +- , -+ they are still going to be out of phase in your case due to the time domain. In your case if you wired pickups out of phase your pickups would be still be out 20° but the polarity will be flipped too so it will sound even more different, not necessarily bad though. Jimmy Page did this a lot.

The only way a phase switch works well is if take for instance a humbucker and wire the coils at different polarities. Since they are so close together the phase shift is not an issue.

The Littlelabs tool works based on an allpass filter so all the frequencies are aligned properly or at least multibands are. Not sure how he does it exactly. IMO it would be over kill for what you are doing in live situation. You could simply put a delay on you first pickup to match the delay (phase shift) of the second pickup.

If you are recording you can use a plugin IBP.
Old 28th September 2013
  #12
Registered User
I generally like a single pup for bass - any phaseness in a bass signal seriously affects the fundamental. So I can understand why exactly lining up the two signals might be very desirable. But I would wonder if you are merely ending up with a signal that is rather similar to a single pup positioned in between the two? Is it worth experimenting shifting the pickup? That sounds like a purer solution to getting the perfect tone - perhaps.
Old 28th September 2013
  #13
Gear Maniac
 

Quote:
Originally Posted by Kiwi View Post
I generally like a single pup for bass - any phaseness in a bass signal seriously affects the fundamental. So I can understand why exactly lining up the two signals might be very desirable. But I would wonder if you are merely ending up with a signal that is rather similar to a single pup positioned in between the two? Is it worth experimenting shifting the pickup? That sounds like a purer solution to getting the perfect tone - perhaps.
Maybe. Of course I'm not gonna go cutting into my bass to move a pickup because it would suit one mix I am intrigued by the guitars with a sliding pickup system.

But more to the point, and not to beat this thread to death I feel there is something to the sound of two pickups working together. A tiny variable delay on one would give a lot of tonal options in addition to fully synced.
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump