Basses with dummy coils …

[CryingBass]

Very funny that a post about pickups can turn the tone towards, wait for it...

 

[Jeff Scott]

Weight?

 

[deepestend]

Serek has a dummy coil in some of his basses

 

[deepestend]

Midwestern B90 Short Scale Bass - Serek Basses

Up for grabs is this brand new Midwestern loaded with both a B90 and Dummy Coil! We don't do Black 'n' Maple very often, but this is a stunner. The tone knob is a push/pull to disengage the Dummy Coil for true single coil tone.

 

[okabass]

I explained it in the last post, but because you obviously didn't understand, it gets you an audible and unavoidable audible effect because of the spacing of the coils that may not be wanted. It's a compromise that one must live with to get the HC. Other pickup configs such as stacked HBs, sidewinders etc do not have this issue and only sense the string in a fairly narrow aperture.

Still not understand how that "comb filter" thing is an answer to this: "why don't all Jazz basses have them (dummy coils)? Is it a tone thing?"

 

[Snert]

"why don't all Jazz basses have them (dummy coils)? Is it a tone thing?"

Because I've already answered it; passive bucking coils load the sensing coil and change the tone.

 

[okabass]

Because I've already answered it; passive bucking coils load the sensing coil and change the tone.

Loads? No, it adds inductance (henry, H), lowers the resonant frequency. Many times it cancels some frequencies too. Sounds less trebly, or more dull.

 

[Snert]

Loads? No

It does actually add a load to the sensing coil that would not be there otherwise, the inductance (and resistance), and as you noted, changes the tonal response of the pickup, often in way many people do not favour.

 

[TrustRod]

Another example for the fun of it. I don't think this was mentioned yet.

MME Tri-Coil Wiring - Bartolini Pickups & Electronics

 

[lalo_garcia-maynez]

Here is the review of bass player magazine of the sterling music man bass from November 1993 … here they discuss how Ernie Ball eliminated hum but gave you a true single coil sound . Interesting

 

[Scarysharkface]

Summing two preamps, one of which has signal, and the other of which doesn't, will give you more hiss than a single preamp. That difference is 3dB if we assume that both preamps are fed with the same impedances, the noise is uncorrelated, and have similar gains. Whether or not the resultant noise is an "issue" depends on a lot of things (including the user's noise tolerance), but the topology does have that disadvantage. The post of mine that you mention is pretty clear, it discusses this disadvantage, which anyone familiar with low noise audio circuit design will understand, but it does not use the word "issue".

If you take an Alembic with this circuit, put the bass in a situation where there isn't a hum field (so that the hum cancellation isn't needed), and then you carefully excise the hum cancellation preamp, the noise level (whatever it is) will go down - every stage in an audio device has inherent noise. Whether or not that's an issue for the user I don't know, I'm just sharing my expertise, and discussing the pros and cons of various schemes.

The hum-cancel coil does have signal. The signal is noise only. Additionally, it has two independent level controls on the back of the bass for any adjustments you might want to make. It is very, very effective.

John

 

[micguy]

The hum-cancel coil does have signal. The signal is noise only.

When audio folks talk about such things, "signal" means the intended signal.

 

[edwinhurwitz]

Another example for the fun of it. I don't think this was mentioned yet.

MME Tri-Coil Wiring - Bartolini Pickups & Electronics

I had a pair of the Guild sized versions of these in my Starfire for a while. Each one had a 5 position switch which would allow lots of variations, all hum cancelling.

They were pretty awesome. Sometimes I wish I hadn't sold them.

 

[Scarysharkface]

When audio folks talk about such things, "signal" means the intended signal.

Talking about Alembic basses, the hum canceler has signal. It's the RF noise. It's not just sitting there dead, doing nothing.

John

 

[ardgedee]

Talking about Alembic basses, the hum canceler has signal. It's the RF noise. It's not just sitting there dead, doing nothing.

That's not signal, that's noise. Which is fine, it's there for collecting noise. But it's not signal.

 

[micguy]

That's not signal, that's noise. Which is fine, it's there for collecting noise. But it's not signal.

One of the key concepts in audio is the signal to noise ratio of the system. The signal is the information you are trying to get through the cable or system; the stuff you are trying to avoid is noise.

 

[Scarysharkface]

That's not signal, that's noise. Which is fine, it's there for collecting noise. But it's not signal.

As far as the circuitry goes, it's signal, just not from the strings. It's canceled out before it gets to the cable, where the signal at that point is the strings in the magnetic fields of the pickups, the noise having been eliminated by how the circuitry deals with the, um, signal.

John

 

[Scarysharkface]

When audio folks talk about such things, "signal" means the intended signal.

When engineers talk about such things, signal is whatever is being passed by the circuitry.

John

 

[micguy]

When engineers talk about such things, signal is whatever is being passed by the circuitry.

John

I am an Engineer, with 40 plus years designing pro audio gear. hopefully we can agree this is a grey area.

 

[Scarysharkface]

I am an Engineer, with 40 plus years designing pro audio gear. hopefully we can agree this is a grey area.

If there were no signal to work with, I doubt the circuit would do anything.

But, sure, we can agree that it's a grey area.

Cheers (and I'm just glad people are interested in this stuff),
John