I Simulated 30 Jazz Bass Pickups So I Wouldn't Have to Buy Them All

Pickups cost €80-150 each. You need two. You can’t return them soldered. So I built a simulator: Python, measured pickup data, the actual circuit the signal passes through. Thirty pickups on the same axes. No vibes, no forum opinions. Just math.

Reading the curves

All curves normalized to 0dB at 200Hz. The differences live above 1kHz.

The resonant peak. The bump in the upper mids. Where it sits defines the pickup’s character. Higher and later = brighter, more string attack. Lower and earlier = thicker, warmer.

Rolloff. How fast the curve drops after the peak. Steep = warm and filtered. Gentle = open and airy. All pickups roll off monotonically after. They have to, it’s a passive circuit.

One dimension of tone. Says nothing about dynamics, touch response, or feel.

The full landscape

Architecture matters, but less than I expected. The extremes hold: brightest are single-coils, darkest are stacked. But in the middle (where the buying decisions actually live), it’s a mix. Some split-coils are brighter than some single-coils.

Single-coil. Widest variation. The lightest-wound vintage specs (CS ’60s, V-Mod II) sit bright. The overwound models (SJB-3, SJB-2) are darker than most hum-cancelling pickups. The Fender Pure Vintage ‘74 (full GuitarNutz2 measurements: L=3.65H avg, C=140pF) lands mid-pack despite its reputation. The “70s brightness” comes from 70s bridge pickup placement (10mm closer to the bridge), not the electrical response. But they all hum when soloed. In a studio, that 60Hz is always there.

Split-coil (side-by-side). Each coil senses two strings, wired in hum-cancelling series. Huge spread: EMG JV at -1.4dB to Bartolini 9J at -7.2dB. The ceramic/steel blade pickups (Model J, Bartolini 9J) sit dark despite low DCR. High-permeability cores push inductance far above what resistance suggests. Inductance drives the ranking more than the architecture label.

Stacked humbucker. Two coils stacked vertically, mutual coupling raises effective inductance and capacitance. The SJB-5 and Ultra Noiseless are the darkest hum-cancelling pickups in the sim. The Wilde J-45N (Bill Lawrence coaxial “Noisefree” design) is a stacked variant with an air gap between concentric coils — brighter than the other stacks, but with the lowest Q in the sim (8.2). Its 20kΩ DCR damps the resonance so heavily that there is no peak. Flat through the upper mids, then rolloff.

Correction (2026-04-12): The Wilde J-45N was previously simulated with estimated specs (R=7.5kΩ, L=3.0H). Confirmed specs from Bill Lawrence (R=20kΩ, L=4.0H) dropped it from rank 6 to rank 17 in the stock passive table. Rankings, charts, and prose updated throughout.

Correction (2026-03-18): The Area J was previously listed here as a stacked humbucker. DiMarzio tech support confirmed all their Jazz Bass pickups are split-coil side-by-side. The “Area” guitar pickups are stacked, but the J-bass version is not. The Area J now appears in the split-coil group.

The stock ceramic proof

The Fender Stock Ceramic (MIM/Squier) measures only 5.74kΩ DCR, the lowest in the entire lineup. But its steel slug pole pieces push inductance to 4.08H, higher than the Alnico CS ’60s at 2.66H. It’s darker than pickups with twice its resistance.

DCR doesn’t predict tone. Inductance does. Steel slugs are cheap and high-permeability; Alnico poles are expensive and low-permeability. The spec sheet says “5.7kΩ” and you think “bright.” The bode plot says otherwise.

DCR vs brightness

If DC resistance determined tone, all the dots would sit on one diagonal line. They don’t.

The Stock Ceramic (5.74kΩ, measured 4.08H) is darker than the Lollar (8.65kΩ, measured 4.19H). Three kilohms less resistance, darker output. Steel slugs vs Alnico poles. The SJB-3 Quarter Pound (13.6kΩ, measured 6.72H) is the darkest in the sim, its quarter-inch Alnico 5 poles and massive capacitance (244pF measured) pulling the resonant peak down to 3.85kHz.

L and C do the work. Resistance is just the easiest number to print on the box.

Measured data as anchor points. The seven measured pickups (solid borders) calibrate the estimates. If a measured single-coil at 3.65H sits at -4.1dB, an estimated one at 3.8H should sit around -4.5dB.

The Lollar question

Three favourites always come up: Fralin, Nordstrand NJ4, Lollar. The Fralins are split-coil (already in the database). The Nordstrand has no published inductance. Pure estimate. But the Lollar is a goldmine.

Lollar publishes inductance for their entire lineup (the only major pickup maker that does). The Echoes of Mars database has independently measured the bridge: R=9.69kΩ, L=4.881H, C=131pF. Significantly higher than Lollar’s published spec (R=8.5kΩ, L=4.0H). Sample variance, or a 2014-era spec. Using the average of measured bridge and published neck values: L=4.19H, C=131pF, 5kHz level = -5.6dB.

The Lollar lands in “warm vintage” territory. Almost identical to the Fender PV ‘74 in character. Both sit about 5dB darker than the CS ’60s at 5kHz. The PV ‘74 gets there with more inductance from heavier winding; the Lollar through both winding and higher capacitance.

The BYO Lightning ($60/set) has vendor-published specs almost identical to the Lollar published specs. Same L, same estimated C. The difference is build consistency, magnet quality, and winding precision. The sim can’t see any of it.

The Model J correction

The Model J was originally estimated too bright. The sim ranked it above the PV74. Anyone who’s played both knows the opposite: PV74 has more snap, Model J has more clank with the resonant peak sitting lower.

The original estimate used an inductance-per-ohm ratio (~0.51 H/kΩ) that was too low for ceramic + steel blade construction. Two measured ceramic/steel pickups from the GuitarNutz2 database told a different story:

The Chopper is the closest analog: same manufacturer, same architecture, same ceramic + steel blades. Just wound for guitar. Both measured ceramic/steel pickups cluster around 0.67–0.71 H/kΩ. Revised Model J estimate: 6.82kΩ × 0.69 = 4.7H.

At 500K volume with cable, the PV74 is now 2.9dB brighter at 5kHz. Easily audible. Consistent with “snap vs clank.” The PV74’s resonant peak sits higher and sharper; the Model J’s is lower and broader. Even with optimized loading (500K vol, minimal cable), the gap holds.

DiMarzio’s updated 4-band treble ratings back this up: Model J = 5.5, Ultra Jazz = 7.0. The sim now agrees with the marketing, the measurements, and the ears. The ceramic/steel L/R correction also applies to the Bartolini 9J (revised from 3.5H to 4.4H). Same blade + ceramic construction.

Model J parallel wiring. The Model J’s 4-conductor wiring allows coil-parallel mode. In parallel, inductance drops by a factor of 4 (4.7H to 1.175H), pushing the resonant peak to 9.1kHz. Brighter than any pickup in the database in any configuration. But even the 500K tone circuit only gives 1.8dB of sweep at that impedance. Coil-parallel requires a switched 100K load to be usable.

The full ranking

The hypothesis: brighter pickups capture more harmonic information for studio DI. You can EQ darker. You can’t recover what rolled off before the converter.

Ranked by 5kHz level. Not a quality ranking: a brightness ranking viewed through that hypothesis. Measured = full RLC data. Adjacent positions within 1dB are within margin of error.

Top two are single-coils with the lowest inductance. Least wire on the bobbin. The CS ’60s has full measured data and confirms the model: measured resonant peaks (3.51kHz bridge, 3.81kHz neck with 470pF load) track the sim within 5%.

The first hum-cancelling pickup at #3 (EMG JV). Its inductance is a rough estimate. The DiMarzio trio illustrates the range within one manufacturer’s lineup:

All three are split-coil side-by-side designs. DiMarzio tech support confirmed: “All of our Jazz Bass pickups are split humbuckers.” The Area J was previously misidentified as stacked based on the Area guitar pickup architecture — those are stacked, but the J-bass version is not.

The Ultra Jazz has the highest DCR but also the highest treble rating. DiMarzio’s own copy: “even with a relatively high DC resistance figure, the Ultra Jazz has very strong, percussive highs.” Hybrid magnet (Alnico 5 rods + ceramic bar) reduces inductance per ohm versus pure ceramic. The Model J’s updated 4-band tone chart now rates its treble at 5.5 (previously 4.0 on the old 3-band chart), brighter than the Area J at 4.5. Magnet type, not architecture, is doing the sorting within this family: ceramic (Model J) vs Alnico 2 (Area J) vs hybrid (Ultra Jazz).

The Model J at #22 is the ceramic/steel proof case. Only 6.82kΩ (the lowest DCR of any hum-cancelling pickup) but -7.0dB at 5kHz, darker than the Fralin at nearly double the resistance. Ceramic + steel blades push L/R to ~0.69 H/kΩ, giving 4.7H despite low winding resistance. The Stock Ceramic at #19: same story, single-coil side. 5.7kΩ (lowest in the table) but -6.0dB. Both disprove “low ohms = bright.” Ceramic + steel = high inductance per ohm.

The three darkest are all over 6H. At that inductance, rolloff starts in the upper mids. Designed for a specific sound, not maximum capture.

Same pickups, different circuit

Cable capacitance loads the pickup node directly, in parallel, regardless of pot value. A 500K volume pot doesn’t shield the pickup from the cable. For the Ultra Noiseless at 5.2H, the difference between cable and no cable is 13dB at 5kHz. The optimized build (500K volume, 500K Greasebucket tone, 22nF cap) changes the loading, but the upgrade happens in two distinct steps.

Left: stock circuit. Centre: passive optimized (500K vol, 500K tone, cable still present). Right: buffered (same pots, onboard JFET buffer eliminates cable loading). The pots alone give a modest, uneven improvement. The buffer is where the ranking reshuffles.

What the pots buy you

Upgrading to 500K volume and 500K tone reduces pot loading on the pickup. Every pickup gets slightly brighter. But the cable is still there, 500pF at the pickup node regardless. For high-inductance pickups, that’s the dominant load, and pots don’t touch it.

The passive optimized spread is actually wider than stock (12.8dB vs 11.4dB). The low-inductance pickups benefit more from the pot upgrade proportionally, while the high-inductance ones are still crushed by cable loading. The Ultra Noiseless gains only +0.5dB from the pot upgrade. The stock Fender gains +1.6dB. The pots help the pickups that needed help least.

The passive optimized ranking

Same 30 pickups through the passive optimized circuit: 500K volume (single-coils get 250K), 500K tone, 500pF cable still present. The ranking barely changes from stock.

The buffer unlock

An onboard JFET buffer (2N5457, fits the control cavity, about eight euro) drives the cable from a low-impedance source. The cable capacitance no longer loads the pickup.

The gold bars are the pot upgrade (stock to passive). The blue bars are the buffer unlock (passive to buffered). For single-coils, the pot upgrade is the bigger share: they were never heavily loaded by cable. For stacked humbuckers, the buffer dominates. The SJB-5 Stack gains +0.1dB from pots, then +13.5dB from the buffer. The Ultra Noiseless: +0.5dB from pots, +12.8dB from the buffer. Their distributed capacitance was resonating with the cable, double-punishing them. Remove the cable and they wake up.

The Fralin Split Jazz gains +1.0dB from pots, then +9.5dB from the buffer. Its high inductance (4.8H) made it the most cable-sensitive. The Model J: +1.2dB from pots, +9.9dB from the buffer.

The buffered ranking

Same 30 pickups through the buffered circuit: 500K volume (single-coils get 250K), 500K tone, onboard JFET buffer (no cable loading).

The Bartolini 9J: #23 stock, #23 passive, #1 buffered. It takes the top spot only when the cable is gone. Its ceramic + steel blades and low DCR gave it the highest inductance-to-resistance ratio in the database. Pot upgrades alone gained it +0.9dB. The buffer gained it +12.9dB. The Fralin Split Jazz: #21 stock, #22 passive (it actually drops one position), then #7 buffered. The Model J: #22 stock, #21 passive, #5 buffered. Every hum-cancelling pickup that was penalised by cable loading sits in the top half after the buffer, not after the pot upgrade.

The single-coils compress into a tight cluster around +2 to +3dB with the buffer. They were never that far apart. The pot upgrade already closed most of the gap. The overwound SJB-2 and SJB-3 still sit last. At 6.7H+, they’re rolling off in the upper mids regardless of loading.

The thickness shift

Spectral balance tells a different story. In the stock circuit, the high-inductance pickups (Model J, Fralin, Bartolini 9J) sit thick. The cable was flattening their peaks, spreading energy across the low-mids. Remove the cable (buffered circuit) and every pickup shifts thinner. The Bartolini 9J drops from -0.6 to -3.6. The Fralin from 0.0 to -2.0. Their warmth was borrowed from cable loading.

The buffered circuit doesn’t just recover treble. It changes the perceived character. Pickups that sounded warm and full through cable-loaded stock circuits can sound leaner and more focused when the cable is out of the equation. EQ adds warmth. Physics doesn’t add treble.

Why some pickups sound thicker

The ranking reshuffled. But numbers at 5kHz don’t tell you what a pickup sounds like in a mix. The Model J “cuts very well, the midrange clankiness means it doesn’t come across as dark, there’s more string energy and musical information than the higher snap of the PV74s. It can be too aggressive, think Stingray.” The PV74 “sits nicely either side of the critical midrange guitar/vocal region, with the treble peak giving useful transient definition to a solid, even bottom.”

That’s not bright vs dark. That’s perceived thickness. Audible even at matched output levels. If the response below resonance is flat for all pickups (it is; the RLC model predicts this), where does the thickness come from?

The answer is Q factor. The resonant peak’s sharpness determines how the pickup’s energy is distributed across the spectrum.

Think of a streetlight.

Same bulb wattage. But a tight beam concentrates all the energy in one spot. Everything outside that cone goes dark. A floodlight spreads the same energy across the whole street. Nothing disappears. Everything is dimmer, but everything is visible.

Q factor is the beam width. A high-Q pickup concentrates its resonant energy in a narrow band. Everything outside that peak goes quieter. A low-Q pickup spreads it. The bass hasn’t changed, the string energy is the same. Q just changes what your ear notices.

The Model J has the highest Q in the database (27.9): tall, narrow peak, energy concentrated in a tight band. That should make it sound thinner, and in the spectral balance, it does. But its peak sits so low (4.7H pushes resonance down into the upper mids) that the concentrated energy lands where your ear reads it as aggressive midrange presence, not brightness. That’s the “clank.”

The PV74 at Q=21.0 is still sharp but broader. The peak sits higher, giving “snap” (attack transients) while the low-mids sit undisturbed. Ultra Jazz at Q=14.5 spreads the most: broad, even, no single frequency dominates.

To quantify this, the sim computes spectral balance: energy in the 80-400Hz band vs the 1.5-6kHz peak region. Closer to zero = thicker. More negative = thinner:

The overwound pickups (SJB-2, SJB-3, SJB-5) cluster top-left: low Q but thick, because their peaks are so low in frequency they don’t steal energy from the fundamentals. The vintage single-coils: moderate Q, thin. The Model J sits alone at far right, highest Q, but its peak is in the mids, not the treble, so it reads balanced rather than thin. The Fralin is the thickest of the shortlisted hum-cancelling pickups (balance ≈ 0).

One pickup, the whole database

The Ultra Noiseless tells the full story. Stock: #25. Passive optimized (better pots, cable still present): #25. Buffered: #2. The pots bought it +0.5dB. The buffer bought it +13.3dB. At +4.8dB through the buffered circuit, it’s the second-brightest hum-cancelling pickup in the database (behind the Bartolini 9J). Measured RLC, silent in every position.

With the buffer in place, solder a small ceramic cap between hot and ground at the blend pot input. That shifts the resonant peak down without touching the coil. The 13dB range in the chart below requires the buffer; without it, the Ultra Noiseless is stuck at -7.9dB regardless of cap value.

Buffered baseline: +4.8dB at 5kHz. Add 50pF and it approaches Model J territory (+4.0). Add 100pF and it’s in CS ’60s territory (+3.0). Add 330pF and it’s in warm vintage range. Add 500pF and it’s darker than anything in the stock ranking except the SJB-2, SJB-3, and Jazz Bomb. 13dB of range. The entire database on one set of coils.

A three-position toggle (50pF / 150pF / 330pF): bright and open, CS ’60s character, warm vintage. Pennies, reversible, no modification to the pickup. But only with the buffer.

Methodology

Every pickup is an RLC circuit. Second-order resonant lowpass: flat through bass and mids, a peak in the upper harmonics, then monotonic rolloff. The simulator models the full signal chain: pickup, blend pot, volume pot, tone circuit, cable capacitance, load. Same circuit for all 30 pickups. All charts: 250K pots, 33nF tone cap, tone wide open, 500pF cable (typical 3m), 1MΩ load.

Load: 1MΩ. This matches the UCX II Hi-Z input impedance (1MΩ). With 250K–500K pots in the signal path, the interface impedance is negligible. The pots dominate the pickup’s load. A 1MΩ load in parallel with a 500K pot is effectively 333kΩ, but the pot is already doing the loading. Cable capacitance loads the pickup node directly, in parallel, independent of pot value. The three-tier circuit comparison (stock / passive optimized / buffered) isolates this effect. The sim load matches the real interface.

Data tiers. Seven pickups have full measured RLC from Echoes of Mars and GuitarNutz2. Four have vendor-published R and L. The remaining nineteen: R from spec, L estimated from architecture and L/R ratio (~0.41 H/kΩ for Alnico single-coils, higher for ceramic and stacked). Estimates carry ±15-20% uncertainty.

How published and measured diverge. Lollar’s published bridge: 8.5kΩ / 4.0H. GuitarNutz2 measurement of a 2014 bridge: 9.69kΩ / 4.881H. 14% higher R, 22% higher L. The sim uses measured values where available.

How reliable are the estimates? Alnico: ~0.41 H/kΩ (measured range 0.37–0.49). Ceramic + steel: ~0.69 H/kΩ, calibrated from DiMarzio Chopper (0.668) and Stock Ceramic (0.710). This correction came from reader feedback. A Model J owner correctly flagged the original 0.51 H/kΩ as too bright. Estimates could be ±0.5H off, enough to shift rankings by 1-2 positions, not enough to change architecture-level conclusions.

Spectral balance. Perceived “thickness” as energy ratio: 80-400Hz low-mid band vs 1.5-6kHz peak region. Captures what 5kHz brightness alone misses. A pickup can be “dark” but still sound thin depending on where its peak sits. The Model J confirmed this: high Q creates midrange aggression, not brightness.

What’s missing. String/body resonance, eddy current damping, magnetic field geometry, nonlinear effects, subjective character. The sim captures the passive electronics. Measurable isn’t everything.

I narrowed 27 to five, then simulated every circuit variable around them. Five pickups, every circuit.