What's with that quack?

For guitars of the straight waisted variety (or reverse offset).
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thisisnickpaige
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What's with that quack?

Post by thisisnickpaige » Sun Aug 12, 2018 3:59 am

Lately i have been getting into Strats, and also recently i have been getting into Daryl Hall and John Oates. John Oates was almost exclusively in the 2nd position on his strat. I get that the quack sound comes from the bridge and middle pickups being in parallel; some of the frequencies cancel out creating that perceived honk. But then why doesn't this happen in the traditional 2 pickup middle position? Aren't both pickups in parallel there to? Is it the reverse wound middle pickup that creates that frequency cancellation? I thought that was just for humcancelling, no?

I've searched google and don't really get a clear answer, just the usual, " ugh i hate the 2/4 position ", " No way, haven't you heard of Mark Knopfler?! " Tons of arguments with no real science. So i figured i'd ask the experts. :)
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Re: What's with that quack?

Post by TeenageShutdown! » Sun Aug 12, 2018 4:26 am

Hall & Oates??? :unsure:

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Re: What's with that quack?

Post by _nash » Sun Aug 12, 2018 5:05 am

I’m going to venture a guess (and then totally regret it probably)...

The bridge and middle pickup being so close together, with relation to the strings. Meaning the frequencies being picked up are different in the bridge-middle positions than in the bridge-neck positions. I base this on my strat. Solid honk from the standard 2/4 positions but I have it wired to also give me bridge/neck in parallel. Similar sound but far less honk.

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Re: What's with that quack?

Post by Maggieo » Sun Aug 12, 2018 9:47 am

thisisnickpaige wrote:
Sun Aug 12, 2018 3:59 am
Lately i have been getting into Strats, and also recently i have been getting into Daryl Hall and John Oates. John Oates was almost exclusively in the 2nd position on his strat. I get that the quack sound comes from the bridge and middle pickups being in parallel; some of the frequencies cancel out creating that perceived honk. But then why doesn't this happen in the traditional 2 pickup middle position? Aren't both pickups in parallel there to? Is it the reverse wound middle pickup that creates that frequency cancellation? I thought that was just for humcancelling, no?

I've searched google and don't really get a clear answer, just the usual, " ugh i hate the 2/4 position ", " No way, haven't you heard of Mark Knopfler?! " Tons of arguments with no real science. So i figured i'd ask the experts. :)
It's not that they're parallel, they're out of phase- they cancel out certain frequencies from each pickup. That's why the two different OOP positions sound different. They are two different coils, so you will get some hum cancelling, but nothing like a humbucker. Even humbuckers can be wired OOP- Peter Green's work in Fleetwood Mac is the gold standard for that tone.


Here's a deep dive:

It might help to understand what phase is and what people mean when they say "in phase" or "out of phase". Technically, phase is the amount of a wave that elapsed relative to some arbitrary point in time. If you consider a simple sinusoidal wave a phase of 0 degrees represents some arbitrary starting point of the wave, every time the wave passes through that same amplitude it's phase has increased by 180 degrees. Lets say we pick an amplitude of 0 as the starting point and we have a simple sinusoidal wave. At a phase of 180 degrees it will pass through zero again, but moving in the opposite direction, and at a phase of 360 degrees it will pass through zero again and be moving in the same direction as it was as 0 degrees.

If two waves are equal and "in phase" they are passing through the same amplitudes at the same time. When two waves are equal and in phase they sum to produce a wave that is twice the amplitude of either of the original waves. We call this constructive interference.

If two waves are equal and 180 degrees out of phase they are passing through opposite amplitudes at the same time. So when one wave is +1, the other would be -1. When two waves are equal and 180 degrees out phase they sum to produce a wave that always has zero amplitude. This is called destructive interference.

If we have an idealized setup, where two pickups are in the same spot on a guitar string, then their output should be exactly the same. In this setup, if they're wired in phase their signals will add and you'll get an output signal that is twice the volume of just one pickup or the other. If you wire up this idealized pickup scenario out of phase you'd hear nothing at all.

But in reality guitar pickups cannot be situated like this. They're always sampling a different part of the string (sometimes slightly as is the case of side-by-side pickups in a humbucker arrangement, sometimes considerably as is the case with a neck and bridge pickup). So the signals they're producing aren't exactly the same. That means combining them out-of-phase doesn't silence the output. Instead you get some interesting destructive interference happening that produces an output that's usually described as "quacky". It's missing some frequencies.

If you combine them in phase things don't get twice as loud, but they do get louder than either pickup on their own, as the same frequencies that were aligning to cancel out in the out-of-phase arrangement, align and add in a constructive interference pattern.
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Re: What's with that quack?

Post by thisisnickpaige » Sun Aug 12, 2018 10:59 am

TeenageShutdown! wrote:
Sun Aug 12, 2018 4:26 am
Hall & Oates??? :unsure:
I hated on them for years, but man, do they have some good songs/grooves/melodies. Yeah, i blame Empire of the Sun's newest album, and Daryl Hall and John Oates for my current Strat-ness. Both have some solid groovin' pop songs, and strat tones galore.
Maggieo wrote:
Sun Aug 12, 2018 9:47 am
It's not that they're parallel, they're out of phase- they cancel out certain frequencies from each pickup.
That makes sense, phase cancelling causing the quack. You mean the pickups due to their distance are out of phase? Like Nash said,
_nash wrote:
Sun Aug 12, 2018 5:05 am
The bridge and middle pickup being so close together, with relation to the strings. ... but I have it wired to also give me bridge/neck in parallel.
Which was my second thought after i posted this. So then maybe we all agree. :D

That being so close there might be some phase issues/cancelation going on but still seems strange, they're not that much closer than the normally 2 pickup situation. But having gotten into the wonderful world of mic-ing things it doesn't take much to be out of phase.

My Strat is wired to have that neck + bridge sound. Took out one of pots, and wired it so it has a master volume, master tone, and a neck always on switch. That's one of my favourite sounds on a Strat, actually, that 'true' middle position sound.


So distance/sonic out of phase causing the quack then?
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Re: What's with that quack?

Post by oid » Sun Aug 12, 2018 12:08 pm

Pickups have a coil and a magnet(s), they each have phase, +/- and N/S, the output(electrical) phase of the pickup is determined by this. Hum canceling is completely a product of the coils phase, if two like coils are wired out of phase they will cancel that background EMI regardless of the magnetic phase.

The phase of the guitar strings (electrical not physical) is determined both the magnets and coils phase. If the coils are out of phase but the magnets are in phase the output will be out of phase and opposites cancel. If we flip the poles on one of the pickups it will now have out of phase magnets and coil from the other pickup but is now electrically in phase so no cancellation of the guitars strings but we are still free from hum.

Two pickup guitars generally avoid the hum cancellation but take the noise cancellation since an in phase mid position is generally more useful.

Things get really complex from there and it is far to hot to think that much, it is kinda to hot to think this much and I am very thankful for spell check right now, kind of wish I had a logic checker as well right now! Guess that is the community.

Perhaps after it cools down I will go into more depth and just doing an all around better job.
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Re: What's with that quack?

Post by thisisnickpaige » Mon Aug 13, 2018 2:34 am

oid wrote:
Sun Aug 12, 2018 12:08 pm
Pickups have a coil and a magnet(s), they each have phase, +/- and N/S, the output(electrical) phase of the pickup is determined by this.
Ah. That makes sense then. So you can be 'in phase' but still have phase cancellation? Groovy. Thanks for explaining. So they have hum cancellation by the coils being reverse wound, but then they have that quack because the magnets being out of phase?
Jesus

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Re: What's with that quack?

Post by Telliot » Mon Aug 13, 2018 6:41 am

TeenageShutdown! wrote:
Sun Aug 12, 2018 4:26 am
Hall & Oates??? :unsure:
Their early stuff was great.
The cool thing about fretless is you can hit a note...and then renegotiate.

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Re: What's with that quack?

Post by Maggieo » Mon Aug 13, 2018 8:33 am

Telliot wrote:
Mon Aug 13, 2018 6:41 am
TeenageShutdown! wrote:
Sun Aug 12, 2018 4:26 am
Hall & Oates??? :unsure:
Their early stuff was great.
I totally concur. Daryl Hall is one of the most gifted singers around. Check out his collaborations with Robert Fripp, too.
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Re: What's with that quack?

Post by countertext » Mon Aug 13, 2018 9:33 am

I’m down with H&O. Don’t tell my wife.

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