Change a pickup's resonant frequency and tone with a loading capacitor

[fig]

Heres my crude clean up of my "cocktail napkin" circuit diagram.

Glad you posted your diagram. I 'napkined' out a schematic this morning and wanted to keep it for future reference. Made a better copy for myself (complete with pastel colors LOL). If you could double check it, I'd appreciate it. As I get older, I trust my interpretation skills less and less LOL.

I left out your component values, 'cause, like you, I usually have to tailor values to each bass.

 

[LeonineAlpha]

@fig Thanks for posting that cleaner diagram.

Just be aware, in my original I have it set so

Pickup Load Switch1 Down=On
Treble Bleed Switch2 Up=On

You noticed that, and cleverly numbered them on my diagram,

So as long as we agree 1+4 are the down÷off positions it looks great!

 

[winegamd]

Pickup Comparison Chart - Guitar Pickups, Bass Pickups, Pedals.
Just in case anyone was wondering what some typical pickup resonant peaks are. Bartolini also lists them for each of their pickups.

 

[micguy]

Pickup Comparison Chart - Guitar Pickups, Bass Pickups, Pedals.
Just in case anyone was wondering what some typical pickup resonant peaks are. Bartolini also lists them for each of their pickups.

Bartolini lists the peak without a capacitive load. The peak will be lower once you hook up a cable. If they listed the pickup’s inductance (EMG does that), it would be more useful.

 

[winegamd]

Since most readers aren't going to know how to measure their pickups, and many manufacturers use a custom wind anyway, it's all just what ifs and guestimation. Resonant peaks at 4.7k, 4.5k, and 4.3k aren't going to be drastically different, or even apparent to most listeners, so in the ball park is usually good enough to then let the ears be the final judge.

For me, knowing where the manufacturers measure their pickups is more to know where I want to move my peak rather than knowing where I am currently. It also helps to establish a reference for what the different peaks sound like since there are plenty of reviews of stock Bart and SD pickups. That way you can listen to your adjustments and compare.

 

[micguy]

Since most readers aren't going to know how to measure their pickups, and many manufacturers use a custom wind anyway, it's all just what ifs and guestimation. Resonant peaks at 4.7k, 4.5k, and 4.3k aren't going to be drastically different, or even apparent to most listeners, so in the ball park is usually good enough to then let the ears be the final judge.

The difficulty with specifying where the unloaded resonant peak is is that the peak will always move when loaded, and will move different amounts, depending on how much interwinding capacitance there is in the pickup to start with. A lower inductance pickup - say 3 Henries of inductance, with 700 pF of interwinding capacitance (I have measured pickups like this), resonates at 3.5 kHz. A higher inductance pickup with lower interwinding capacitance - say 6 henries and 100pF respectively (this is the neighborhood where P pickups live) resonates unloaded at 6.7 kHz.

So, the P will be brighter, right? Well, if you load each of them with 650 pF (a typical cable value), the lower inductance pickup's resonance moves down from 3.5 to 2.8 kHz. The P pickup? It goes from 6.7 to 1.8 kHz. Those are definitely different, and will definitely sound very different than what you expected from the unloaded resonant peak spec. The specs make you think the higher resonant peak pickup will sound brighter and/or more extended, but the information is insufficient to make even a crude judgement about how they will sound.

 

[groovaholic]

Just added a loading capacitor to the neck pickup on my main bass; a Dingwall Z2 that I converted into a Z3 by adding the neck pickup.

The original 2 pickups were Bartolinis and the added neck pickup is a Dingwall P-Tone.

Problem was, they never worked together all that well - the Bartolinis have a warm, punchy low-midrange voice while the Dingwall pickup is bright and hi-fi sounding.

So yesterday I thought about using a cap to tame the brightness of the P-Tone, and I found this thread.

Simple soldering and a $.20 part (that I already had) made my #1 bass much better, and the suggestion to demo different caps with alligator clips was incredibly helpful; 4n7 was too dark, 3n9 was better but still muffled, but 2n2 sounded great and made the Dingwall pickup's voice match the Bartolini pickups almost perfectly.

 

[micguy]

Just added a loading capacitor to the neck pickup on my main bass; a Dingwall Z2 that I converted into a Z3 by adding the neck pickup.

The original 2 pickups were Bartolinis and the added neck pickup is a Dingwall P-Tone.

Problem was, they never worked together all that well - the Bartolinis have a warm, punchy low-midrange voice while the Dingwall pickup is bright and hi-fi sounding.

So yesterday I thought about using a cap to tame the brightness of the P-Tone, and I found this thread.

Simple soldering and a $.20 part (that I already had) made my #1 bass much better, and the suggestion to demo different caps with alligator clips was incredibly helpful; 4n7 was too dark, 3n9 was better but still muffled, but 2n2 sounded great and made the Dingwall pickup's voice match the Bartolini pickups almost perfectly.

Sounds good - you made your bass better by yourself!

 

[groovaholic]

Sounds good - you made your bass better by yourself!

Last night at rehearsal, I was able to run the EQ flat on my bass and my amp - and listening back to the recording, the bass is just sitting in the mix better.
Since I'm not cutting treble in an attempt to rein-in that one pickup, the overall bass sound has more clarity.

Best $0.37 (current Mouser price for the cap in question) I ever spent!

 

[winegamd]

Here is a fun site if you want to play with things.

CircuitLab - Editing "Unnamed Circuit"

It is basically an online spice modeler for a pickup. Its a little bit easier to use than most spice programs.

 

[Lemon]

Is that Loading Cap working only in instruments with a passive circuit or also with active electronics and passive pickups ?
Since that seems to work with P basses, it should also work with hum bucking J split coils, with 3 and 2 poles for a 5 string, or am I way off ?

I know a kid with an Affinity Strat, and I went in and loaded those pickups with loading caps and shorting coils (oops - another secret out of the bag)

These shorting coils and loading caps work the same way as a passive crossovers in speakers. At least I would say the circuits are the same and do the same thing.

This is really interesting =)

 

[kgbeast]

Is that Loading Cap working only in instruments with a passive circuit or also with active electronics and passive pickups ?
Since that seems to work with P basses, it should also work with hum bucking J split coils, with 3 and 2 poles for a 5 string, or am I way off ?



These shorting coils and loading caps work the same way as a passive crossovers in speakers. At least I would say the circuits are the same and do the same thing.

This is really interesting =)

The caps discussed above are to offset resonant frequency of a passive pickup... Basically the cap needs to go in parallel with the pickup, before anything else is done. You can do it before a passive pickup gets to the preamp. Actually the stingray preamp has 2.2nf cap at the input to do just that, shift the resonant frequency.
In case of active pickups however, such small cap will not really do anything worth notice and a larger cap will just act as a low pass filter. I use the stingray amp in a bass with 2 active pickups and I simply clip that 2.2nf cap off. That said, I did try with the cap and there was no noticeable difference, however I decided to clip it off as it was put in there to work with the specific pickup which I do not use

 

[micguy]

These shorting coils and loading caps work the same way as a passive crossovers in speakers. At least I would say the circuits are the same and do the same thing.

This is really interesting =)

Shorting coils impart damping at the resonance, and a 3 dB per octave rolloff above that. Speaker crossovers are a different thing.

 

[micguy]

Is that Loading Cap working only in instruments with a passive circuit or also with active electronics and passive pickups ?
Since that seems to work with P basses, it should also work with hum bucking J split coils, with 3 and 2 poles for a 5 string, or am I way off ?

Loading caps work in any bass where the pickups are passive, whether or not there is a preamp on board.

 

[Lemon]

Shorting coils impart damping at the resonance, and a 3 dB per octave rolloff above that. Speaker crossovers are a different thing.

Ok it seemed similar, I meant shorting by resistor, coil or capacitor.

Loading caps work in any bass where the pickups are passive, whether or not there is a preamp on board.

Ok thanks great.

In case of active pickups...

Also thanks for the answers also =)
I meant passive pickups with an preamp.

The caps discussed above are to offset resonant frequency of a passive pickup... Basically the cap needs to go in parallel with the pickup.

Reading yesterday the first time about this, Im still trying to get the whole picture =)

Probably I should mention that im not a native english speaking, so talking in technical terms is a bit tricky for me =)

I got 2 sets both are hum cancelling.
One is the original fender pickup, 2 wires, there is several points on the pickup where the stacked coils are connected. It has not much dynamics.
Bright sounding, low mids are not emphasized.

The other one is Nordstrand NJ5FS, 3 and 2 Poles split, 3 wires.
1 wire is ground, and one for each coil, its hooked up, hot leads in parallel.
Except that it has much more dynamic range and seems to have more output, its similar thing bright sounding, low mids are not emphasized.

 

[kgbeast]

The stingray preamp I use, the 3-band.DYI, there is 2.2nf cap for resonance peak shifting. I believe it was paired with a specific MM pickup at that time. The MM pickup I use is a bit mid-rangy with that value. So I ended up trying few small value caps that I had laying around and ended up changing for 560pf, which is almost a quarter of original. It gives a little bit crispier and scooped sound. No cap at all by the way sounded not that great, I found it a bit flat with muffled mids.
I use the same preamp with VFL active and the stock cap vs no cap sounds the same I think. So I left it no cap. I will play with that a little more if I get chance, but the VFLs sound very good with that preamp stick or without the 2.2nf cap.

 

[Lemon]

Yesterday i went to the electronics store and got some caps, 1000Pico , 2200Pico and 3300Pico two of each. I installed one of each across each of the pickup clamps.
Neck Input --->hot-3300-ground
Bridge input-->Hot-3300-ground

I started with the 1000pico. Nothing ...
so I tried the 3300Pico.
Not sure if the 3300 really did something,
if it did anything, it made the low bass area sound a bit fuller and the treble area a bit less harsh but almost nothing.
So either I have hooked it up wrong and actually didnt understand,
how that works, or that pickup has the resonant point very high up.

I`ll get a couple of 10000 pico...

 

[Lo-E]

Those are very high values for a loading cap. More typically, you’ll be looking at a couple hundred picos on average.

 

[kgbeast]

Yesterday i went to the electronics store and got some caps, 1000Pico , 2200Pico and 3300Pico two of each. I installed one of each across each of the pickup clamps.
Neck Input --->hot-3300-ground
Bridge input-->Hot-3300-ground

I started with the 1000pico. Nothing ...
so I tried the 3300Pico.
Not sure if the 3300 really did something,
if it did anything, it made the low bass area sound a bit fuller and the treble area a bit less harsh but almost nothing.
So either I have hooked it up wrong and actually didnt understand,
how that works, or that pickup has the resonant point very high up.

I`ll get a couple of 10000 pico...

In my Donlis MM pickup, 3.3nf which is 3300pf makes a noticeable difference, makes it sound mid-rangy to a bad amount. In my case, the cap is on the preamp pcb, where it ends up simply between hot and ground of the pickup (in parallel with pickup before any volumes and stuff).
I tried 10pf (not difference)
120pf (maybe something)
200pf (something not too bad)
470pf (nice beefy scooped)
560pf (better beefy scooped)
1nf (starting on a midrange boost)
2.2nf (quite mid-rangy, but ok)
3.3 (starting to be twangy)
4.7nf (too twangy)

All of that of course a matter of personal taste. For some what I like might be bad tone... I picked 560pf as my face for this specific setup.

 

[Lemon]

Thats weird.
The caps are in the clamp shorting PU Hot and PU Ground for each pickup.

Could it be, because it is all wired in Parallel ?
The 2 coils are in parallel and the pickups also.
Or because of the volume pot ?
That is probably 1MegΩ or even more.

There is 2 Hot wires coming from each pickup, one white one grey one from each coil.
For each PUP, these wires are both in the Hot terminal.
Ground in Ground.
I dont see why else it doesent work.

Its this Preamp
On the second page of that PDF,
one page after the title page,

FLEXCORE
INSTRUCTIONAL OVERVIEW
with the Picture below, there is an explanation, which explains the clamp terminals.

Unfortunately there is no technical info at all on the Nordstrands.
I only know that they have 2 coils around 2 poles and around 3 poles.

I will end up throwing everything out, get some single coils with a known low peak like Barts and make a 12 position tone switch like in that video
Was it 12 ??? every second position.

That switch is very cool and all whats needed.

Thanks, I appreciate the a lot =)