DiMarzio Area T Analysis & Review

[antigua]

A user on TDPRI named Bruxist sent me a loose Area T pickups to measure. I've never had my hands on any of the Area stacked humbuckers, so I appreciated receiving this. I had analyzed the Fender Vintage Noiseless here www.strat-talk.com/threads/fender-vintage-noiseless-analysis-and-review.404990/ , so I can compare the two.

From a design standpoint, the Area is much closer to a single coil. The top coil is almost a standalone single coil, with the DC resistance and inductance expected from a Tele single coil, while the bottom is a much smaller coil. The Fender Noiseless top and bottom coils, on the other hand, appear to be nearly symmetrical coils.

The measurements below show that the lower coil has an inductance of only 1 henry, while the top coil has an inductance of 3.3 henries. You'd think think top top would produce a higher voltage than the lower coil, but a significant design difference between the Area and the Fender Noiseless, is that while the Fender's AlNiCo pole pieces equal the height of the whole pickup, the Area's AlNiCo poles only extend through the top coil. The bottom coil instead has nine permeable buttons (steel, iron, ferrite), similar if not the same as are embedded in some of their PAF style humbucker bobbins, and the permeable buttons appear to significantly boost the voltage output.

I did a separate test with an exciter coil parallel to the coils rather than on-axis with them, with the exciter coil about an inch away from the pickup, which induces roughly equivalent magnetism in the top and bottom coils, and the plot shows nearly identical voltage output from the top and bottom coil when the "noise" source is coming from the side. Even though the lower coil is so much smaller and has a lower inductance, the permeable buttons act as noise antennas and ultimately the noise voltage is about the same from both coils. When the induction from from the top of the pickup, like a magnetized guitar string, the voltage output of the top coil is significantly higher, as much as 15bBV based on testing.

From a design goal standpoint, the Area is a clear winner over the Fender Vintage Noiseless I had tested. It appears to function almost entirely the same as a single coil, with the noise cancelling coil causing very minimal drag on the output signal while at the same time, likely an effective noise canceler.

As far as how they compare to vintage spec pickups tone-wise, the loaded resonant peak of ~3.0kHz is like a slightly hotter Tele bridge pickup.

The Area T can be split, but because the lower coil is so well isolated, splitting doesn't yield much benefit. The plot below shows that the split performance is nearly identical to the series performance.


DiMarzio Area T Bridge

- DC Resistance: 7.417K ohms (upper coil: 6.131k, lower coil: 1.44k )
- Measured L: 4.049H (upper coil: 3.370H, lower coil: 1.0644H )
- Calculated C: 52.85pF (upper coil: 241.3pF, lower coil: 57.94pF)
- Gauss: 550G (AlNiCo 2)

Unloaded: dV: 14.1dB f: 5.24kHz (black)
Loaded (200k & 470pF): dV: 6.3dB f: 2.96kHz (blue)
Split loaded (200k & 470pF): dV: 5.9dB f: 3.03kHz (red)





Noise test; when the upper and lower coil are subjected to roughly the same magnetic input the produce nearly the same voltage output. This is representative of noise, because extraneous noise comes from far away sources, and is seen by the upper and lower coils in nearly the same proportion.



By contrast, if the exciter is place above the pickup, where guitar strings would be located, the upper coil's voltage output is significantly greater. This is representative of the signal from guitar strings, because they are close to, and above the pickup.





parellel induction (noise):



on axis induction (guitar strings):





Permeable buttons:

[wgen]

Thank you Antigua, very interesting as always.
I have a stacked noiseless Duncan YJM neck pickup for no particular reason, of this one I only use the top coil alone, because the sound is more vintage and glassy.. The stacked was too dark, too high inductance for me. I liked the sound so I left it permanently wired as a single coil, top bobbin only.
This pickup has 4 wires, two for each bobbin, and the Alnico poles are from top to bottom of the entire pickup.
I simply left the wires of the lower bobbin unwired.
Does the lower bobbin have an influence to the tone in any way? Thank you

[antigua]

Mar 22, 2020 14:22:15 GMT -5 wgen said:

Thank you Antigua, very interesting as always.
I have a stacked noiseless Duncan YJM neck pickup for no particular reason, of this one I only use the top coil alone, because the sound is more vintage and glassy.. The stacked was too dark, too high inductance for me. I liked the sound so I left it permanently wired as a single coil, top bobbin only.
This pickup has 4 wires, two for each bobbin, and the Alnico poles are from top to bottom of the entire pickup.
I simply left the wires of the lower bobbin unwired.
Does the lower bobbin have an influence to the tone in any way? Thank you

The analysis of the Fender Noiseless showed that the magnetic induction in the bottom coil, from the top of the coil, was significantly higher than with area, by a wide margin. I'm sure there are two reasons 1) the Fender's top coils is shorter, so the bottom coil is closer to the strings, and 2) the AlNiCo rods extend through to the bottom coil. But you don't want the string sending any magnetic change, or "signal" to the bottom coil, because it all cancels out. The DiMarzio Area definitely causes less of that cancellation, probably be a significant margin, due to the design differences. I've never seen the Seymour Duncan stacks, but how well they perform must depend on whether the design is closer to Fender or DiMarzio. If you preferred the sound of the top coil alone, I would think the bottom coil must be causing excess cancellation. 

[wgen]

Thank you. Yes, the design is definitely more similar to the Fender noiseless in the other thread. The two coils to me seem similar or equal, even if I never measured these two in particular. The Alnico rods go through the entire pickup, too. There is a thin layer of what I thought it was copper along all the bottom of the pickup.
Even if I use this one as a single coil only, I have to say that I find the pickup particularly quiet if compared to others.
Anyway, the wire seems so thin.. In the past, Frank Falbo, who has worked for Seymour Duncan, said that the YJM pickup should have 45 Awg wire.
If I leave the two wires, which connect the lower coil only to the circuit, unwired like they are now, does the capacitance vary some?

[ms]

The area T might use a flat sheet of magnetic material between the two coils to help reduce the coupling between them by guiding the flux from the vibrating string that passes down through the Alnico pole pieces back to the string without passing through the lower coil.  Or maybe it does not need it since the Alnico cores lose a lot of flux on the way down in any case.

I see that the sum of the two individual inductances is more than that measured with the two in series.  This is as it should be;  the mutual inductance is negative.  But it is not much less, meaning that the coupling is low.

I think that what follows is the primary reason why a coil with a high permeability core can have enough signal, but lower inductance:  Start with a coil identical to the top (active) coil.  Replace the Alnico with high permeability material.  This increases its signal output and its inductance.  Take off half the turns; this halves the signal output.  How much did the inductance go down?  About a factor of four since inductance varies with the square of the number of turns for a coil with the flux confined to the high permeability core (or for constant geometry for an air core, but this is not the case here.) 

So with careful design you can reduce the inductance of the bottom coil by perhaps a few times while keeping up the sensitivity.

This might not be the only reason for the improvement, but it would be difficult to model this with good enough accuracy to tell.

[antigua]

Mar 23, 2020 6:19:44 GMT -5 ms said:

The area T might use a flat sheet of magnetic material between the two coils to help reduce the coupling between them by guiding the flux from the vibrating string that passes down through the Alnico pole pieces back to the string without passing through the lower coil.  Or maybe it does not need it since the Alnico cores lose a lot of flux on the way down in any case.

I see that the sum of the two individual inductances is more than that measured with the two in series.  This is as it should be;  the mutual inductance is negative.  But it is not much less, meaning that the coupling is low.

I think that what follows is the primary reason why a coil with a high permeability core can have enough signal, but lower inductance:  Start with a coil identical to the top (active) coil.  Replace the Alnico with high permeability material.  This increases its signal output and its inductance.  Take off half the turns; this halves the signal output.  How much did the inductance go down?  About a factor of four since inductance varies with the square of the number of turns for a coil with the flux confined to the high permeability core (or for constant geometry for an air core, but this is not the case here.) 

So with careful design you can reduce the inductance of the bottom coil by perhaps a few times while keeping up the sensitivity.

This might not be the only reason for the improvement, but it would be difficult to model this with good enough accuracy to tell.

I think there is some separation between the AlNiCo and the steel buttons, because the Guass strength over the buttons measured only about 30 Guass. I'd expect it to be well over 100 at least if they were touching. I like them a lot, and will probably buy some Strat sized versions, and I can pull them apart more. I have to return this one intact. 

[sumitagarwal]

antigua have you ever tried using the bottom coil as a noise cancelling dummy coil *for other pickups in the guitar*?

Since the bottom coil is so well isolated I wonder if it could be very effective in providing cancellation for traditional single coil Strat pickups in the neck and middle positions, where the geometry and space is less conducive to a stacked design.

[stratotarts]

Next step might be to enlarge the radius of the bottom coil.

[sumitagarwal]

Mar 23, 2024 9:32:45 GMT -5 stratotarts said:

Next step might be to enlarge the radius of the bottom coil.

Maybe another way to effectively increase the area of the bottom coil without additional windings would be to distribute the  bottom coil across three pickups. So you could have three Strat pickups that have 1/3rd wind bottom coils each, and these can be wired in series to provide full cancellation for a single top coil.

[stratotarts]

That would only work with some certain number of top coils selected. You said one, but what if two are selected?

[sumitagarwal]

Mar 23, 2024 9:47:19 GMT -5 stratotarts said:

That would only work with some certain number of top coils selected. You said one, but what if two are selected?

If you put two top coils together in parallel maybe you could roughly cancel that with one of the bottom coils?

[stratotarts]

You could have a switching network to engage the proper number of bottom coils. It's an interesting idea, needs some further thought...

[sumitagarwal]

Mar 23, 2024 10:58:56 GMT -5 stratotarts said:

You could have a switching network to engage the proper number of bottom coils. It's an interesting idea, needs some further thought...

I wonder how hard the Areas are to disassemble. Maybe could grab a hotter top coil and a weaker bottom coil and combine them, although they won't have the level of disparity we're talking about.

Really we'd need the series inductance of the cancellation coils to be about equal to the highest signal inductance which in most cases will be the inductance of the hottest single coil. From there wiring strategies can bring the cancellation inductance down to the necessary level.

Could also work fine with split humbuckers. For those who like Teles with a PAF in the neck, might be great to run an Area T in the bridge and use the Area T lower coil to cancel hum when splitting the neck pickup for way more (noiseless) versatility.