Brainstorming for Low-Z bass pickups.

[bea]

Please let me start with the thread on the new PUs for this bass: hipshot supertone variant

I am pretty unsure on the final outcome and have difficulties to describe the sound i would like to achieve.

First of all, i like the sound of my Epiphone EB-3 clone (shortscale, Hipshot bridge, neck pickup modified by additional steel between the coils, bridge PU a Wlkinson Minihumbucker with (probably) ceramic magnet in Musicman-alike "10% scale" position. String Pyramid black nylons, foam pieces in the bridge. Sound deep with some nice highs even on the neck PU. Attack EB-3-like "slow".

The RD shall be similar but anyway contrastingly different. It is intended for old school rock. THe bass has a much faster attack than the EB-3 und a huge sustain even played acoustically.

I need the deep growl from the EB-3 in the neck position and a tone on the bridge PU that should be more "fenderish" but still mix well with the tone of the neck PU.

My ideas are low Z sidewinders on the neck and either a sidewinder or a Low-Z humbucker built around 9.5 mm magnets. Form factor of a PAF (except the height) is mandatory. I have a set of cheap chinese guitar humbuckers and would like to reuse as much of them as meaningful:




As to the sidewinders: l a relatively wide steel blade in the Center, possibly laminated. Magnets outside the coils sitting on the steel rods.

A useful concept?

Alternatively an Alnico bar between the bobbins or a steel blade and magnets in the body. Last possibility: two lipstick-like PUs pointing to the central blade.

I have no idea on the sound these concepts might produce and would be grateful on some hints.

[David Schwab]

As to the sidewinders: l a relatively wide steel blade in the Center, possibly laminated. Magnets outside the coils sitting on the steel rods.

A useful concept?

Yes, that will work.

Alternatively an Alnico bar between the bobbins or a steel blade and magnets in the body. Last possibility: two lipstick-like PUs pointing to the central blade.

I have no idea on the sound these concepts might produce and would be grateful on some hints.

They should all work. Then you just find the one you like.

[bea]

May i ask from which one i would get the "fattest" bass response - fat in the meaning of the warmth the Viva blade humbuckers (which seem to be pretty close to Seymour Duncan's SH-13) do not offer. Treble will of course come from the low-Z wiring.

Mhmm, and i'd like to finalize somewhere in the field "Darkstar / RD-Artist / T-Bird" - which i gues would allow me to find settings sounding well as an alternative to 7enders automatically.

Any hint which concept *might* be the most successful?

BTW: after reading the specs of the RD artist bass pickups - a PAF guitar pickup would come pretty close, wouldn't it?

[bea]

Let's continue here. Not for the bass shown above, but for its sister - SG shape, alder body, same neck, same hardware.

Again pickups in standard humbucker cases.
This time P90 / Bisonic inspired, LowZ - traditional approach with a few 100 turns of thick wire - 0.2mm because i have plenty of that...

Here my first attempt to build the bobbins:





Originally, i intended to use Alnico magnets, but regarding this amount of steel ceramic or Neo magnets will probably be superior, wouldn't it?

Again due to lack of experience i am unsure on the strength of the Neos to be used - what about Neo rod magnets for approximating the flat bars, e.g., 8 rods 4mm x 100 mm N45 for each pickup?

[David King]

Bea, I think I'd try the Neo in the N32-35 range and use a fairly substantial sized one if you have the room on the bottom for it, say 5x5mm or 4x6mm in cross section.
It's easy enough to find some ceramic C8 bars and try those too. What you have so far looks great.

[bbsailor]

Please let me start with the thread on the new PUs for this bass: hipshot supertone variant

I am pretty unsure on the final outcome and have difficulties to describe the sound i would like to achieve.

First of all, i like the sound of my Epiphone EB-3 clone (shortscale, Hipshot bridge, neck pickup modified by additional steel between the coils, bridge PU a Wlkinson Minihumbucker with (probably) ceramic magnet in Musicman-alike "10% scale" position. String Pyramid black nylons, foam pieces in the bridge. Sound deep with some nice highs even on the neck PU. Attack EB-3-like "slow".

The RD shall be similar but anyway contrastingly different. It is intended for old school rock. THe bass has a much faster attack than the EB-3 und a huge sustain even played acoustically.

I need the deep growl from the EB-3 in the neck position and a tone on the bridge PU that should be more "fenderish" but still mix well with the tone of the neck PU.

My ideas are low Z sidewinders on the neck and either a sidewinder or a Low-Z humbucker built around 9.5 mm magnets. Form factor of a PAF (except the height) is mandatory. I have a set of cheap chinese guitar humbuckers and would like to reuse as much of them as meaningful:

[ATTACH=CONFIG]22603[/ATTACH]


As to the sidewinders: l a relatively wide steel blade in the Center, possibly laminated. Magnets outside the coils sitting on the steel rods.

A useful concept?

Alternatively an Alnico bar between the bobbins or a steel blade and magnets in the body. Last possibility: two lipstick-like PUs pointing to the central blade.

I have no idea on the sound these concepts might produce and would be grateful on some hints.

Bea,

See this link: Ingram Engineering. This is all about obtaining the best signal to noise ratio for the input impedance range and signal level range of the input stage. This also puts the pickup to more design thoughts, low Z or high Z? With high Z the transmission line affects the tone and noise. At low Z the transmission line has minimal audible effects.

Assume that the mic matching transformer has a 1 to 12 turns ratio (such as the Shure A95 series) so that a 6000 turn high Z pickup should only need about 600 turns of AWG 32 (equal to .2mm dia wire) maximum to be boosted back into the same range by the mic matching input transformer or mic preamp.

I would try winding the first 200 turns and break out a tap, another 200 turns for the second tap and the final 600 turns for the third or end tap of the coil.

This will allow you to use the impedance matching and mismatching (by using various switched coil taps) to act as an audio filter. Depending what you want to hear, read up on the effects of impedance/resistance mismatches on transformer overall frequency response, peaking or rolloff. Generally, more coil turns boosts the high Z pickup output and adds more capacitance to roll off the high end. With one tenth the turns you are working at the one hundredth the impedance level of a 500K high Z volume pot will be 5K on a 500 to 600 turn low Z pickup. Make the capacitors about 100 times higher in value to scale the same as in a high Z circuit.

Try to use same pole facing magnets on each side of the metal pole pieces on the bottom. This will help spread out the magnetic field wider to accomodate the inductance of a good voltage level in the outer turns of the coil which are farther away from the stronger magnetic field. The magnetic field strength at double the distance is eight times weaker or 1 over the distance cubed.

I hope this gets you started. Post your results.

Joseph Rogowski

[bea]

Dear Josef, thanks for the hints.

They show me that i am on the right track: i wanted to do 500 turns per pickup and add the signals with an inverting op amp with a gain of 20 dB. Or if i´m lazy just use 250 turns and 26 dB amplification. Passive C-switching per pickup - the bridge pu will probably profit from a different voicing tan the neck pu. Maybe alternatively use SVFs - capacitances in the range of a few µF might already be a bit unhandy.

And yes, the tele neck pu i did a while ago with 500 turns of .2 mm wire and a volume pot of 2.5 k works perfectly well into my small mixing console.

EDIT: just ordered the magnets for both pickup projects.

[Mike Sulzer]

These op amps would go in the instrument? If so, then you probably want to select one that draws low or moderate current, and these in general achieve best SNR with a higher impedance pickup, that is, one that puts out more voltage. There is no point is using a transformer in the guitar with a pickup design where you can vary the number of turns and wire size; there is no long line to add capacitance and lower the resonance. I think the best procedure is to use enough turns to get good SNR, but not so many that you affect the highs.

The situation to use moderately low or medium impedance is when you want a passive instrument and use a transformer or just a preamp designed for very low noise voltage at the amp end.

500 turns into a low current low noise op amp is adequate for electric guitar unless you want to use very high gain, but it is far from the best you can do. For a really good acoustic sound and high quality high dynamic range recording, I would want to do better.

Dear Josef, thanks for the hints.

They show me that i am on the right track: i wanted to do 500 turns per pickup and add the signals with an inverting op amp with a gain of 20 dB. Or if i´m lazy just use 250 turns and 26 dB amplification. Passive C-switching per pickup - the bridge pu will probably profit from a different voicing tan the neck pu. Maybe alternatively use SVFs - capacitances in the range of a few µF might already be a bit unhandy.

And yes, the tele neck pu i did a while ago with 500 turns of .2 mm wire and a volume pot of 2.5 k works perfectly well into my small mixing console.

EDIT: just ordered the magnets for both pickup projects.