Easy Pickup Question

Building pickups from the ground up

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Folkie
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Easy Pickup Question

Post by Folkie »

I recently got my 330/12 back from the shop after having the hi gain pickups replaced with toasters. I immediately noticed that something was up with the small knob. Can someone please tell me the exact way the volume, tone, and blend controls are supposed to work?
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jdawe
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Re: Easy Pickup Question

Post by jdawe »

The small knob is just a second volume pot wired in series with the neck pickup volume pot, and with the third pole ungrounded. In contrast the main volume pots are grounded so that when you turn the pot all the way down it grounds out the signal from the pickup and cuts the pickup off entirely. Because the so-called "blend" pot isn't grounded the signal from the neck pickup doesn't cut out entirely when you turn the small knob all the way down. Rather, when you turn the small knob all the way down you get slightly less volume from the neck pickup than if you turn it all the way the other way, but you always get something.

So when you have the pickup selector switch in the middle position, the small knob "blends" the two pickups by adjusting the relative contribution from the neck pickup. It has no effect on the bridge pickup. While I intend no criticism of the fifth knob -- I love it and use mine all the time -- the fact is that it doesn't really do anything that you couldn't also do by tweaking the main neck volume knob a bit.

As for how the other controls work: the main volume knobs are simply variable resistors with one side connected to ground and the other to the output jack. Essentially, turning the knob increases or decreases the amount of resistance in the circuit that connects the pickup to the output jack, which changes the current flow, which in turn changes the volume.

The tone knobs are variable resisters wired in series with a capacitor, with the other end going to ground. The tone circuit is wired in parallel with the output circuit. The capacitor essentially acts like a filter -- it allows higher frequency signals to pass through more readily than lower frequency signals. The more of a signal that goes through the capacitor and escapes to ground, the less of it goes to the output jack and into your amplifier. Signals prefer the path of least resistance, so changing the amount of resistance in the tone circuit changes the amount of high-frequency signal that gets removed from the output signal, thereby changing your tone.
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jps
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Re: Easy Pickup Question

Post by jps »

Folkie wrote:I recently got my 330/12 back from the shop after having the hi gain pickups replaced with toasters. I immediately noticed that something was up with the small knob. Can someone please tell me the exact way the volume, tone, and blend controls are supposed to work?
Tell us what the knob is doing, now, compared to what it used to do. Maybe your tech decided to rewire things besides just replacing the pickups?
Folkie
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Re: Easy Pickup Question

Post by Folkie »

Problem solved! :D
need-a-ric
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Re: Easy Pickup Question

Post by need-a-ric »

Give us the details please...could be educational for the rest of us.
Folkie
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Re: Easy Pickup Question

Post by Folkie »

need-a-ric wrote:Give us the details please...could be educational for the rest of us.
Ned,

I have two Rickenbacker 12-strings: a 1991 330/12 and a 2010 360/12. I swapped 7.4k toasters for the stock hi gains on both. My confusion about the guitar controls (most specifically the small fifth knob) stemmed from a dramatic difference in tone between the two guitars, something I should have expected from the beginning.

I got accustomed to tweaking the treble on the 360/12 with the small fifth knob, and it works exactly as Jonathan explained: with the pickup selector in the middle position (both pickups running) turning the small knob clockwise decreases the volume of the neck pickup and thus accentuates the bridge pickup for a more trebly sound. Turning that knob counterclockwise increases the bass frequencies by increasing the signal from the neck pickup. Before I had the pickups changed on the 330/12, I used the bridge pickup almost exclusively. With both pickups running simultaneously, I always set the fifth knob completely clockwise for a brighter sound. But once I put toasters on the 330, I guess I expected it to sound more like my 360 than it actually does. To my initial dismay, I found that dialing in the knobs on the 330 exactly as I do on the 360 did not create the same (or even similar) tones. Specifically, my 330 sometimes produces treble to the point of harshness, with very little body or low end, until I make the necessary amp adjustments.

At first the sounds were just so different that it felt to me like the knobs weren't working right. But today, when I tested out the controls, everything seemed to be in working order. Just two totally different guitars, each of which has a distinctive tone.

So that's a roundabout way of answering your question. If you have any other questions, I'd be glad to help out in any way I can. :)

Robert
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jps
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Re: Easy Pickup Question

Post by jps »

On my 330 I usually have the 5th element knob set about halfway to get a good balance between the two pickups and then I roll off the neck pickup's tone control to make it mellower sounding, if needed.
Folkie
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Re: Easy Pickup Question

Post by Folkie »

Sounds like a good way to get many nuances out of that 330! 8) PM Sent. :D
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