Pickup replacement problem???

[barryman]

Guys - here is my query.
I have a lovely bass with two pickups - the usual PJ split plus single bar pup. Controls are a master volume, a tone control, and a three-way selector switch. It plays fine but sounds far quieter than my other basses when used at the same volume settings.

I have tried testing the output using a multimeter. When the switch is in the up position (neck P pickup???) I get a reading of 4.7k. When switch is right down (the JB bridge pickup?) I get reading of 12.5k. However, when switch is in the middle position (presumably that means both pickups working together??) the reading is only about 3.7k
The sound volume is pretty much the same between top and middle positions.

Am I reading this all wrong - I don't know where any fault may be. I can't understand the big difference between 4.7k on one pup and 12.5 on the other one Do I need to replace pickups or could it be a faulty switch? Or is my method of testing wrong?? What test does anyone recommend if not the way I have already done it?

Any advice appreciated.

Edited May 21, 2015 by barryman

[PlungerModerno]

All I know to do is to confirm those readings and pickup selection suspicions by taking a coin, and tapping it on the pickup to confirm which pickup's signal are being sent to the jack. Then you'll know which switch settings correspond to which pickup selections - and the jack resistance value of each.

P.S. don't have the amp / headphones up on full when you tap the pickup - it tends to be quite loud.

[BigRedX]

Generally P pickups have a higher resistance than J types so I would guess that the lower resistance is the J pickup. The combined figure looks right for the two pickups wired in parallel.

Some basses are just louder or quieter than others.

[Grangur]

[quote name='BigRedX' timestamp='1432243197' post='2779731']
Generally P pickups have a higher resistance than J types so I would guess that the lower resistance is the J pickup. The combined figure looks right for the two pickups wired in parallel.

Some basses are just louder or quieter than others.
[/quote]

+1 You can also check out the individual pups by disconnecting the circuit and connect each pup in turn, direct to the jack.

Lovely looking bass btw

Edited May 23, 2015 by Grangur

[geoham]

[quote name='barryman' timestamp='1432238548' post='2779684']
Guys - here is my query.
I have a lovely bass with two pickups - the usual PJ split plus single bar pup. Controls are a master volume, a tone control, and a three-way selector switch. It plays fine but sounds far quieter than my other basses when used at the same volume settings.

I have tried testing the output using a multimeter. When the switch is in the up position (neck P pickup???) I get a reading of 4.7k. When switch is right down (the JB bridge pickup?) I get reading of 12.5k. However, when switch is in the middle position (presumably that means both pickups working together??) the reading is only about 3.7k
The sound volume is pretty much the same between top and middle positions.

Am I reading this all wrong - I don't know where any fault may be. I can't understand the big difference between 4.7k on one pup and 12.5 on the other one Do I need to replace pickups or could it be a faulty switch? Or is my method of testing wrong?? What test does anyone recommend if not the way I have already done it?

Any advice appreciated.
[/quote]

There is more to the output of a pickup than just the DC resistance. I had a MIM P Bass with a very high output and low resistance. The resistance basically tells you how much wire is wound round the magnet.

You'll get an overall lower value with both on, since they are wired in parallel. (It's exactly the same theory as using two 8 ohm speakers to give 4 ohms in total)

Basses have different output levels. All is probably normal.
In my experience, louder often doesn't mean better sounding

[iiipopes]

What is the factory spec for the P-pickup? If it is only reading 4.7 kohms at the jack, it might have a windings problem. Traditional P-bass pickups usually have about 10,000 winds of 42 gauge wire on them, and end up reading about 10 to 11.5 kohms on a meter at the hot lead, not through the jack. Measuring through the jack with both volume and tone dimed would lower that reading due to the interaction of the circuit, but only by about 500 ohms.

The impedance drop with the selector switch in the middle is normal. But if the bridge pickup reads @ 12.5 kohms, then if the P pickup should read about 10.5 kohms, and with the switch in the center should read about 5.5 kohms at the jack.

I respectfully disagree about the nature of the output. If the P-pickup reads that low on a meter, then it probably has an open coil, which means the pickup is only functioning on inductance, not conductance through the circuit, and will have a substantial fall off in signal output.

Recommendation: unsolder the "hot" lead of the pickup from the selector switch and measure the pickup. If it doesn't read in the traditional range, or the reading is not stable, it may have to be rewound or replaced.

Edited June 5, 2015 by iiipopes

[geoham]

[quote name='iiipopes' timestamp='1433512637' post='2791734']
What is the factory spec for the P-pickup? If it is only reading 4.7 kohms at the jack, it might have a windings problem. Traditional P-bass pickups usually have about 10,000 winds of 42 gauge wire on them, and end up reading about 10 to 11.5 kohms on a meter at the hot lead, not through the jack. Measuring through the jack with both volume and tone dimed would lower that reading due to the interaction of the circuit, but only by about 500 ohms.

The impedance drop with the selector switch in the middle is normal. But if the bridge pickup reads @ 12.5 kohms, then if the P pickup should read about 10.5 kohms, and with the switch in the center should read about 5.5 kohms at the jack.

I respectfully disagree about the nature of the output. If the P-pickup reads that low on a meter, then it probably has an open coil, which means the pickup is only functioning on inductance, not conductance through the circuit, and will have a substantial fall off in signal output.

Recommendation: unsolder the "hot" lead of the pickup from the selector switch and measure the pickup. If it doesn't read in the traditional range, or the reading is not stable, it may have to be rewound or replaced.
[/quote]

4.7k is exactly what my MIM P was. Researched it back then and it's normal. I. I think the type of ceramic magnet they use helps give a high output, but sounded very harsh to me. I swapped mine for a Tonerider, much nicer.