Passive Mid control for a 5 string Bass

[JasonG]

I am rewiring a friends OLP MM style bass. The pickup is a little over 6K and sounds lame. Are there any recommendations on the design? What frequency should I aim for? I was going to go with a 1.2 H inductor like in the Bill Lawrince system but I as far as I know that is really tuned for a guitar.
I did a search and didn't find anything.
Is there a problem with my question? Is it lacking any information or vague in any way?

[David King]

This is just not something we would do nowadays. It's kind of a forgotten art. Most of us would probably tell you to rewind the pickup and push it up towards 8 K (series) or down to 4.8 maybe. I don't wind MMs so I really don't have a clue here.
Villex (William) is the only bass pickup maker that had a passive mid control and I don't know if he even recommends it anymore. He must have built the choke into the pickups or...?

[JasonG]

Why has that approach been abandon by most? Bill lawrince still has his Q filters listed on his website and even spills the beans, parts values and all. I just found that out while working on this response. It looks like he has changed the parts values a bit since the 70's judging from schematics I have.

[David Schwab]

You change the frequency with the cap value. I've had success using a Radio Shack audio transformer for an inductor. In the book Electronic Projects for Musicians, Anderton uses also uses a transformer, Mouser part # 42TM-019.

The inductors in the Gibson Ripper were made from a 1/4 steel bolt and three steel washers, and would as a humbucker with two coils. I think it was 36 AWG wire.

[Stan H]

I still sell alot of them.

[David Schwab]

I still sell alot of them.

I forgot you made those. I used to put those types of controls in all my basses. I still think they are pretty cool. I'm rewiring a FirstAct guitar like an L6-S and I'm going to put in a midrange control and all.

[automan]

Have you played with the Aguilar preamps? I dont know if you care to go active, but I think they song great.

[JasonG]

Thanks for the help guys! I always wondered what those old Gibson inductors looked like. Those bobbins look like the ones used in the some of the V2's Gibson put out in the late 70's. I have checked around for inductors and it seems like the best place to get them is Allied they are cheap and small enough to mount in most control cavities. Before I order some of those I am going to try out some inductors I just scraped out of some telephone line switchers and see how they go over they look right and there free.
At this point I am resisting active electronics.

[David Schwab]

Thanks for the help guys! I always wondered what those old Gibson inductors looked like. Those bobbins look like the ones used in the some of the V2's Gibson put out in the late 70's.

Yeah, and the L6-S. Those are Bill Lawrence designed guitars. I know a guy that rewound one for an L6-S, and it really is just a bolt, three washers and a nut! Very clever design.

Bill has said that he had more elaborate designs for those guitars, but Gibson restricted how much they wanted to spend on making them, so he had to simplify them.

[David King]

All the inductors I've seen in Gibson guitars were inside the tin cans. They looked like an off the shelf inductor. I know they are popular in guitars but I haven't seen too many in basses besides the 60s and early 70s Guilds, Gibsons and god knows what else. I wouldn't mind knowing a bit more bout them. Of course the problem is that most cheap bass amps will take a nice sounding passive bass and turn it into complete craptone.

[belwar]

Some guy just walked into my shop with a gibson "The ripper" bass. Never seen one before. It's got that whole setup inside, and the bill lawrence sidewinders in it. I took a bunch of pictures of it (including the screw based inductor). I'm going to try and unsolder the parts tommorow and take measurements of the inductor and the pickups.. Freq scans, inductance, self capacitance, dcr, etc.

Im interested to learn about that passive mid boost.. cool idea.

[David Schwab]

I had a set of Ripper pickups once. They sound pretty god, but have ridiculously small pole screws. I guess Bill had a reason for that. I could do without the series out-of-phase setting on the pickup selector too. But it sounded cool in Jocko Homo by Devo.

[belwar]

I had a set of Ripper pickups once. They sound pretty god, but have ridiculously small pole screws. I guess Bill had a reason for that. I could do without the series out-of-phase setting on the pickup selector too. But it sounded cool in Jocko Homo by Devo.

I figured they were mini bucker pole screws

[David Schwab]

I figured they were mini bucker pole screws

I think they are.

[belwar]

I forgot to bring it home with me but I took measurements of everything today.. Pickups, pots, and the inductor. I'll post them tommorow for the heck of it.

What a wierd pickup. both read approx 6.2kohms. Each coil was (probably not on purpose) offset by .1kohms. I.e. Coil one was 3.13 and the other 3.23. The bridge has Gauss readings of 300 at each pole, while the neck was 590 at each pole.

High resonance peak at 12.31khz (calculated using a frequency generator, 1MOhm resistor and a Fluke DMM).

Theres a bassist at my work who just LOVED the tone out of the thing. Then on the other hand I was telling another friend about them and he thought they were just terrible (like my spelling).

bel