The Bad-Sonics aka my home made Bi-sonic pickups

[SGD Lutherie]

It is very interesting the principle on which the Bisonics and the Dark Star are based. It could be applicable to any type of pickup (also Fender like pickups) but the construction would not be simple.

Now I am thinking about a new step forward: using neodymium magnetsin a Bad-Sonic. I know that you guys are alnico aficionados, but I winded several Jazz and Precision pickups using neodymium, and they are the best sounding pickups on my basses, not only to my poor and humble ears, but also to the ears of professional musicians that frequent my house. The drawback I see in using the neodymium in Bad-Sonics is the risk of string pulling, but I think thet I can handle increasing the distance.
I also use the neodymium pickups in a special configuration to improve the sound of Artec pickups in my Bach Thunderbirds, and ensure you that they are hot!

Nice work!

Neos sound great in bass pickups. I use them.  The trick is to use steel poles, and then charge them with neos on the bottom.

The real Bi-Sonic had steel poles, and they went through a laminated steel keeper. Then the alnico magnets pressed up against that.

A real DarkStar/Bi-Sonic looks like this:

You can see the keeper bar covered with coper tape.
 

Side view:



A guy over at TalkBass made a clone with neos:

[dadagoboi]

Please explain how that thing is a 'clone' of a Bisonic.  Does it exhibit ANY of the measurable physical properties of an original?  Are the acoustic properties close to an original?

[SGD Lutherie]

Please explain how that thing is a 'clone' of a Bisonic.  Does it exhibit ANY of the measurable physical properties of an original?  Are the acoustic properties close to an original?

The coil is the same dimension and wound the same. It uses steel poles and a laminated keeper block.  It lacks the adjustable poles, but that has nothing to do with the way the pickup sounds, and was probably overkill. Pickups don't have acoustical properties, but they do have electrical properties (DC resistance, inductance etc.). As long as you get close to those, and keep the coil geometry the same, it will sound extremely close, if not exact.

It sounds pretty much like a Bi-Sonic. He posted some sound clips of it, but I couldn't locate the thread. I think the clips were with ceramic magnets, which was in the pickup with the green circuit board bobbin.

So the important things here is the size and shape of the coil and how it's wound, and the amount of steel and strength of the magnets. Everything else is just how the pickup looks.

I'm going to start making a similar pickup, but with a blade instead of poles.

[dadagoboi]

By acoustic properties I guess I meant frequency response curves.  Stuff that can be objectively measured, I don't know the technical jargon.  I do seriously doubt those arbitrarily placed neo magnets accurately reproduce the originals.  The ability to adjust each pole piece to individual string height and strength is a major feature of the bisonic/dark star design IMO.

It sounds pretty much like a Bi-Sonic.

And this looks pretty much like a Rolls Royce, probably sounds close too.

[Dave W]

Same design principles and coil geometry can get you in the area, but IMHO it won't be any closer than "similar."

[SGD Lutherie]

Same design principles and coil geometry can get you in the area, but IMHO it won't be any closer than "similar."

Well then you have to ask why not? What is there about the original that's different? As long as you have the same amount of steel (for inductance) and similar strength magnets, along with the right coil geometry and windings, you have the same pickup. All the rest of the pickup, like the adjusters and the chrome surround, would have a minimal impact on the tone. The Bi-Sonic doesn't need to be so large either, and without the adjusters you only need to house the coil. If you replace the larger alnicos with the same strength of neos, and maybe increase the amount of steel in the keeper, you can fine tune the pickup to get that tone.  If you heard the sound clips you can hear that it sounds like a Bi-Sonic. I'll see if I can find them.

I think if Fred Hammon had started to remove parts until he hit the bare minimum needed to retain the tone, most of the pickup beyond the coil, poles and magnet would be gone.

[Dave W]

I think everything matters except the color of the bobbin. No, a chrome surround (to use your example) won't have the same effect as changing the coil shape, that doesn't mean it makes no difference. A minimal impact on tone is still an impact.

[SGD Lutherie]

I think everything matters except the color of the bobbin. No, a chrome surround (to use your example) won't have the same effect as changing the coil shape, that doesn't mean it makes no difference. A minimal impact on tone is still an impact.

That's true. The surround is conductive, so it might bleed off some high end, although it's not very close to the coil. But you would have to try one both ways and see.

Apparently Rick Turner felt the pickup could be improved by adding a second magnet to it. Fred has further improved it with more laminations to the keeper.

So with these changes you still get the sound of a Bi-Sonic, but it might sound slightly different from a particular Bi-Sonic.

OK, I found the thread with the DarkStar clone. It has sound clips of a real one too.

http://www.talkbass.com/forum/f38/dark-star-vs-my-own-mpustar-801085/

[Beer of the Bass]

Hi, this is my first post here! 
Those are interesting looking pickups, tore00.  It's great to see something outside of the standard Fender-ish designs.  I'm curious about the Ferrite beads you used to do the job the laminations did in the original.  Are they the cylindrical type with the holes through them that usually get used for RF suppression, and do your poles pass through them?  I take it the logic in using them was to get some ferrous material in there to alter the inductance without using a solid, conductive lump of steel?  I may try something similar if I can gather up the materials. 

[SGD Lutherie]

I take it the logic in using them was to get some ferrous material in there to alter the inductance without using a solid, conductive lump of steel?

The real Bi-Sonic, as well as the DarkStar use laminations for the keeper. The function of the keeper is to conduct the magnetic field to the poles, and allow them to slide through.

If you aren't using adjustable poles, you could probably do away with the keeper, but that would alter the inductance a bit.

The reason for using laminations is to reduce eddy currents, which dampen the resonant peak of the pickup, and reduce some of the high end.

[exiledarchangel]

I was thinking about that too, you could simplify more the pickup design by replacing the steel poles and keeper bar with a steel blade. You could experiment a bit with the thickness to adjust inductance or maybe use a thin blade and add a brass plate. Or you could use a reverse T style blade, thick part on bottom to stick the magnets to and thin at the top to reduce the sensing area and the inductance. Sky is the limit.

[SGD Lutherie]

I was thinking about that too, you could simplify more the pickup design by replacing the steel poles and keeper bar with a steel blade. You could experiment a bit with the thickness to adjust inductance or maybe use a thin blade and add a brass plate. Or you could use a reverse T style blade, thick part on bottom to stick the magnets to and thin at the top to reduce the sensing area and the inductance. Sky is the limit.

That's kind of the approach I'm taking with my "Neo-Sonics."

[exiledarchangel]

Adjustable polepieces are overrated anyway!

[SGD Lutherie]

Adjustable polepieces are overrated anyway!

I agree! 

[Beer of the Bass]

I wonder how close a P90 style magnet arrangement without the laminations could get to the sound of the originals?  I guess that a solid keeper would lose some highs from eddy currents, and leaving the keeper out would change the inductance, so wouldn't have its peak at the same frequency?  I'm trying to figure out if tore00s ferrites are an attempt to get some iron in there to get the inductance similar to the Bisonics/Darkstars, without losing highs through eddy currents.  I can't see where they are from the pictures, so I, guessing they're in the centre of the coil perhaps. 
I have very limited tooling, so I'm not going to try copying anything too closely - if I can get it somewhere in the ballpark I'll be happy.