A look inside a Lane Poor MM5.

[ModulusMK]

Usually, steel will increase the inductance, which will lower the resonant frequency.

As well as with the capacitance... they're both reverse proportional with the resonant peak. Raise the inductance or/and capacitance the resonant peak will go lower. What seems Lane was doing here is that he got fairly bright and clear sounding coil (small inductance and capacitance, which leads to heavy wire and lower turns), and all that was flattened with the double shielding of brass and copper... they have slightly different impact over the coil, in this case making it sound very clear and balancing the high end. Remember when you add metal cover over standard pickup... you loose some of the highs. I think this is what is happening here, just in his case he made too bright coil and flattened it with the double shielding.

[belwar]

M4.0W Measurements

Measurements for M4.0W Pickup

All Measurements w/ Common Ground Wire Attached too include Shielding.

DC Resistance at 68 degrees, pickup and 7" lead only: 7.32K

These reading measured using an Extech 380193 using the "SER" setting.

Inductance @ 120hz: 1.571 H
Capacitance @ 120hz: 1079.0 nF
AC Resistance @ 120hz: 7.328K
Q as the secondary Parameter of Capacitance @ 120hz: .1650
D as the secondary Parameter of Capacitance @ 120hz: 6.030
Inductance @ 1000hz: 1.591 H
Capacitance @ 1000hz: 16.049 nF
AC Resistance @ 1000hz: 7.652K
Q as the secondary Parameter of Capacitance @ 1000hz: 1.308
D as the secondary Parameter of Capacitance @ 1000hz: .7643

These reading measured using an Extech 380193 using the "PAL" setting.

Inductance @ 120hz: 59.51 H
Capacitance @ 120hz: No Reading nF
AC Resistance @ 120hz: 7.326K
Q as the secondary Parameter of Capacitance @ 120hz: .1638
D as the secondary Parameter of Capacitance @ 120hz: 6.105
Inductance @ 1000hz: 2.537 H
Capacitance @ 1000hz: 9.877 nF
AC Resistance @ 1000hz: 7.649K
Q as the secondary Parameter of Capacitance @ 1000hz: 1.283
D as the secondary Parameter of Capacitance @ 1000hz: .7795

Unloaded Resonance frequency:

The AC Voltage read at the peak was 0.593v
The resonance peak was 6.890khz

[belwar]

M4.0N Measurements

Measurements for M4.0N Pickup

All Measurements w/ Common Ground Wire Attached to include Shielding.

DC Resistance at 65 degrees (It was cold), pickup and 7" lead only: 7.31K

These reading measured using an Extech 380193 using the "SER" setting.

Inductance @ 120hz: 1.703 H
Capacitance @ 120hz: 995.0 nF
AC Resistance @ 120hz: 7.306K
Q as the secondary Parameter of Capacitance @ 120hz: .1802
D as the secondary Parameter of Capacitance @ 120hz: 5.548
Inductance @ 1000hz: 1.713 H
Capacitance @ 1000hz: 14.89nF
AC Resistance @ 1000hz: 7.535K
Q as the secondary Parameter of Capacitance @ 1000hz: 1.430
D as the secondary Parameter of Capacitance @ 1000hz: .6988

These reading measured using an Extech 380193 using the "PAL" setting.

Inductance @ 120hz: 54.81 H
Capacitance @ 120hz: No Reading nF
AC Resistance @ 120hz: 7.306K
Q as the secondary Parameter of Capacitance @ 120hz: .1780
D as the secondary Parameter of Capacitance @ 120hz: 5.610
Inductance @ 1000hz: 2.56 H
Capacitance @ 1000hz: 9.770 nF
AC Resistance @ 1000hz: 7.534K
Q as the secondary Parameter of Capacitance @ 1000hz: 1.402
D as the secondary Parameter of Capacitance @ 1000hz: .7133

Unloaded Resonance frequency:

The AC Voltage read at the peak was 0.842vac
The resonance peak was 7.522khz

[belwar]

M4.0N Measurements WITHOUT common ground

Measurements for M4.0N Pickup

All Measurements are WITHOUT Common Ground Wire Attached to exclude the shielding from the equation and look just at the coils+mags.

DC Resistance at 65 degrees (It was cold), pickup and 7" lead only: 7.29K

These reading measured using an Extech 380193 using the "SER" setting.

Inductance @ 120hz: 1.707 H
Capacitance @ 120hz: 992.0 nF
AC Resistance @ 120hz: 7.289K
Q as the secondary Parameter of Capacitance @ 120hz: .1811
D as the secondary Parameter of Capacitance @ 120hz: 5.5526
Inductance @ 1000hz: 1.710H
Capacitance @ 1000hz: 14.901nF
AC Resistance @ 1000hz: 7.445K
Q as the secondary Parameter of Capacitance @ 1000hz: 1.445
D as the secondary Parameter of Capacitance @ 1000hz: .6917

These reading measured using an Extech 380193 using the "PAL" setting.

Inductance @ 120hz: 54.33 H
Capacitance @ 120hz: No Reading nF
AC Resistance @ 120hz: 7.285K
Q as the secondary Parameter of Capacitance @ 120hz: .1792
D as the secondary Parameter of Capacitance @ 120hz: 5.58
Inductance @ 1000hz: 2.544 H
Capacitance @ 1000hz: 9.854 nF
AC Resistance @ 1000hz: 7.444K
Q as the secondary Parameter of Capacitance @ 1000hz: 1.416
D as the secondary Parameter of Capacitance @ 1000hz: .7059

Unloaded Resonance frequency:

The AC Voltage read at the peak was 0.942vac
The resonance peak was 8.952khz

[ModulusMK]

Huge difference in peak frequency with and without shielding ground wire. Almost 1.5kHz.
That's the difference between normal and balanced output what was stated about I guess. Shielding not to go to ground.

[Mike Sulzer]

The pickup coil is primarily an inductance. Therefore you can expect to measure the inductance with the Extech*. But you certainly cannot measure its capacitance at a frequency where the inductance and resistance have much lower impedances.

*There is an unknown error (probably small at 120 Hz) in the inductance measurement due to eddy currents, which appear as a parallel resistance. The Extech has an error in addition to that stated in the manual when both series and parallel resistance are present.

Measurements for M4.0N Pickup

All Measurements w/ Common Ground Wire Attached to include Shielding.

DC Resistance at 65 degrees (It was cold), pickup and 7" lead only: 7.31K

These reading measured using an Extech 380193 using the "SER" setting.

Inductance @ 120hz: 1.703 H
Capacitance @ 120hz: 995.0 nF
AC Resistance @ 120hz: 7.306K

...

[David Schwab]

Shielding not to go to ground.

You will get a lot of extra noise that way.

[David King]

I was talking to Dave Meadows at Audere audio again and he thinks that the HB he tested had some serious anomalies. He says it tested open on DCR and that he was convinced there must be a capacitative coupling going on to get the results he saw on the scan. None of the other LP scans he got looked like that and none tested open either...

[ModulusMK]

You will get a lot of extra noise that way.

Yes, you do get noise. But that is what the wiring diagram for LP's says... shielding from pickup to be connected to cavity shield only and all that not to go to signal ground (as on the drawing, there is ONLY the signal ground connected to the jack)... only ground from coils. That way you get the balanced sound from pickups with higher freq peak. Henry from Legacy said this to me, without mentioning freq, that's from the measurements.

[Mike Sulzer]

This does not agree with my experience as to how guitar pickups and the associated circuits function. Unless you are using a preamp, the dominant capacitance in the pickup system is the guitar cable. With the cable connected, capacitances due to body cavity, internal shielded cable, bases and covers are all relatively small. That is, eliminating one or more of them does not make a significant difference. (Audible effects due to covers and bases are due to eddy currents, not the extra capacitance.)

I do not think that leaving all the internal shields, body cavity, etc., disconnected from the ground on the jack does anything useful.

Yes, you do get noise. But that is what the wiring diagram for LP's says... shielding from pickup to be connected to cavity shield only and all that not to go to signal ground (as on the drawing, there is ONLY the signal ground connected to the jack)... only ground from coils. That way you get the balanced sound from pickups with higher freq peak. Henry from Legacy said this to me, without mentioning freq, that's from the measurements.

[David King]

Lane was only adamant that the shields not be connected to the backs of the pots. He did intend that they be connected to the ground at the output jack, just not upstream in the circuit.

I installed a ground-lift switch in my PU tester bass to disconnect the shielding around pickups. It makes no audible difference to the tone other than to add the hum.

[David Schwab]

Yes, you do get noise. But that is what the wiring diagram for LP's says... shielding from pickup to be connected to cavity shield only and all that not to go to signal ground (as on the drawing, there is ONLY the signal ground connected to the jack)... only ground from coils. That way you get the balanced sound from pickups with higher freq peak. Henry from Legacy said this to me, without mentioning freq, that's from the measurements.

Basses don't have balanced circuitry. And it's still ground. I also run my shields separate from the coils, but guess what? One end of the coil connects to the shields and ground at the output jack! If it doesn't do so sooner. There is no problem with connecting the grounds and shields together on the back of a pot, since it all goes to the same place, a few inches away.

Where it does matter is running into a preamp like an Audere that uses a balanced input.

[David King]

Speaking of LP docs, I just found an old folder full of then and am including some interesting tidbits...

[David Schwab]

Lane was only adamant that the shields not be connected to the backs of the pots. He did intend that they be connected to the ground at the output jack, just not upstream in the circuit.

It's all at the same ground potential. There is no upstream! This is also true of utilizing start grounding in a passive guitar or bass. There is no point in doing so at all. None. Daisy chaining the backs of the pots to ground causes no problems.

I installed a ground-lift switch in my PU tester bass to disconnect the shielding around pickups. It makes no audible difference to the tone other than to add the hum.

Exactly.

[David King]

David,
I agree that it makes no difference to you and me but it did make a difference to Lane and I'm sure that's where the confusion comes in where ModulusMK and Henry P are somehow misinterpreting what Lane was saying (which is why I mention it.)