Adding a Second Magnet to a 1967 SF-1 Bisonic

[Mosthigh]

So I finally got around to popping the hood on my '67 SF-1 bisonic pickup, and discovered it only has one alnico magnet (I think, it could be ceramic). This wasn't too surprising, as I've read many do, but there is a space for another magnet and was wondering which one would go 'best'. I'm not sure what the stock magnet is rated at. I know the newer Guild and Novak ones use alnico 2's. If I added a 5 or 8 even, would that jive well with the stock one? Or should they be the same rating? I like the idea of beefing up the already fat sound (like Jack Casady and Phil Lesh), but have very limited knowledge of any ramifications for doing so, other than too powerful a magnet(s) could cause string pull, and perhaps too strong an output for the electronics (resistors?).

 

[fronobulax]

I have vague recollections of discussions about whether a second magnet even makes a difference, or not. I also recall discussions about remagnetizing the existing magnet and getting good results. There is a Jack Casady interview at https://www.flyguitars.com/interviews/jackCasadyGuildBass.php where he says, about the custom Flying V bass with Bisonics

The only thing I did as I did in the other basses, I would increase the Alnico magnets in the pickups.

but I don't know if that means he added a magnet, swapped one out for a stronger magnet or what.

I'll tag @mellowgerman because his memory and sense of experimentation is much better than mine. @mgod doesn't visit much but most of what I think I remember came from his experiences or stories he told so maybe he can correct my memory

 

[Mosthigh]

There's a similar quote from that article, referring to his Starfire: "I took the pickups, that was my idea, and flipped them out and added another Alnico magnet on the other side so each pickup had twice as much power."

I also found a thread on Talkbass that provided some info. Yet, whether it was an alnico 2 or 3 or 5 on the Starfire, remains unknown. Much of the talk revolves around the pickup on the JC Epiphone. Someone mentioned 2 or 3 would probably be better than 5 or higher.

Edwinhurwitz said: "Casady's double magnet thing came about with the Hagstrom Bisonic pickups that were in his Starfires. If you look at the bottom of the pickup, there's a slot for an additional magnet, so Bear, aka Owsley Stanley, put one in there as an experiment and it improved the sound."

https://www.talkbass.com/threads/jack-casady-and-adding-extra-magnets-to-pickups.1527657/

 

[fronobulax]

There's a similar quote from that article, referring to his Starfire: "I took the pickups, that was my idea, and flipped them out and added another Alnico magnet on the other side so each pickup had twice as much power."

I also found a thread on Talkbass that provided some info. Yet, whether it was an alnico 2 or 3 or 5 on the Starfire, remains unknown. Much of the talk revolves around the pickup on the JC Epiphone. Someone mentioned 2 or 3 would probably be better than 5 or higher.

Edwinhurwitz said: "Casady's double magnet thing came about with the Hagstrom Bisonic pickups that were in his Starfires. If you look at the bottom of the pickup, there's a slot for an additional magnet, so Bear, aka Owsley Stanley, put one in there as an experiment and it improved the sound."

https://www.talkbass.com/threads/jack-casady-and-adding-extra-magnets-to-pickups.1527657/

Missed that quote. Thanks.

I'm pretty sure Edwin has been around here but don't recall his ID.

I wish my search fu was better because I recall the claim that some had two magnets "from the factory" and that some people who had tried both could hear no functional difference. Maybe that conversation wasn't on LTG?

 

[hieronymous]

Paging @edwin !

 

[Mosthigh]

I actually pm'd @edwinhurwitz over at Talkbass and he suggested I contact Rick Turner Guitars regarding nos alnico's. I did just that and they said they would sell me a couple specifically cut for Bisonics. I'll report back on the outcome.

 

[mellowgerman]

Looking forward to your findings! If you can, it would be great to hear a before&after recording.

My first vintage Starfire, from early 1966, had a single-magnet Bisonic in it and it sounded fantastic. Naturally there are lots of variables at play, including the wood of the instrument itself, the hardware, the strings, etc. In any case, I actually ended up ordering a custom Dark Star pickup from Fred Hammon with a single magnet to try and get a pickup that was closer to the sound of that early '66 bass's pickup.

I didn't have enough patience (nor the equipment) to properly A/B that pickup with the original and actually installed it in a Fender Mustang bass in the middle position... so it's hard to say just how similar the pickup sounded to that old one, but either way, it sounded great! If I recall correctly, that pickup ended up in my friend's '68 Starfire bass, where it still rumbles up a storm to this day.

You may already know this, but at some point in the late 60's, the stock Hagstrom Bisonic pickups found in Starfires started getting 2 magnets, somewhere along the production line... There was some discussion/debate/maybe-speculation that the buzz around adding a magnet (thanks to our Frisco friends) resulted in this change OR that it may have just been how they started coming from Hagstrom OR that it was preferable to have 2 magnets for higher aperture in the bridge position and a single in the neck position, but as Guild used up their stock of Bisonics, they ran out of single-magnet specimens, so the last run of dual-Bisonic Guilds got two double-magnet pickups... Hard to say, but fun to think and chat about!

I should also add, I honestly couldn't tell you which iteration I prefer these days. If the opportunity arises and my friend and his Starfire come down from CT or I go up there with mine, we'll try to do some half-way useful A/B'ing. That said, my 1970 Starfire, as it currently exists, is the best sounding one I've had the pleasure of playing... after tons of swapping and testing, I've found that a standard Dark Star in the neck position and a standard Novak BS-DS in the bridge position is more or less what I would consider the perfect balance. The Dark Star of course is wound a little lighter for a touch of extra articulation and the Novak is wound to vintage Hagstrom spec, so it correspondingly has a bit of a beefier sound. Both have 2 magnets underneath. The last thing I wouldn't mind trying some day is swapping the neck position Dark Star out for a single-magnet specimen, but I love the current combination and tone so much, that I'm honestly not sure it would be worth the effort.

 

[fronobulax]

<veer>
Given a bisonic style PU installed in a bass, how does someone determine how many magnets are in it? Start taking things apart until you can make a visual inspection?

One magnet? (A Novak BSDS) Edit: No. Look more closely.



Two Magnets? (vintage Bisonic that formerly belonged to @mellowgerman)

 

[lungimsam]

Both pictured have two magnets.
Your NS Starfire also has 2 mags.
They do not pass under the metal strip in the middle they are two separate rectangular magnets. If you look closely at magnet number one in the picture you can see the lip on its edge riding slightly above the metal strip in the center of the pick up.

 

[fronobulax]

Both pictured have two magnets.
Your NS Starfire also has 2 mags.
They do not pass under the metal strip in the middle they are two separate rectangular magnets. If you look closely at magnet number one in the picture you can see the lip on its edge riding slightly above the metal strip in the center of the pick up.

OK. I didn't really see the second magnet in the Novak, but it is there. Thanks.

So anyone got a gut pic of a one magnet Bisonic and is there any way to tell besides disassembly?

 

[lungimsam]

Mellow might have one.

 

[Mosthigh]

If no one else does, I'll post a pic before I add that second alnico in a few days. (I meant to take one when I had it open the other day - d'oh!).

 

[mellowgerman]

Two magnets? (vintage Bisonic that formerly belonged to @mellowgerman)

One important thing to mention here, though it would likely be considered vintage at this point (going by the debatable definition of anything "30+ years old" -- which would also make me vintage!) This pickup actually turned out to be an early prototype-stage DarkStar, as previously noted here:

A Veer into Bisonics

Wait...Bisonics...some had one, some had two magnets? Let the debates begin!!

letstalkguild.com

It is also the same pickup that has earned a permanent residency in the neck position of my red 1970 (where I first found it). Though it's unclear if it potentially consisted of vintage Hagstrom components - practically every part of it looks like it's of 60s vintage - the factor that ultimately and very strongly suggests the early DarkStarness is the squared off height adjustment paddles. That was a Hammon design choice, presumably to get rid of some unnecessary metal, but also maybe to require slightly less routing for the cavity.

 

[mellowgerman]

Mellow might have one.

True! I will have to do some digging. I may not have photographed my '66 SFB pickup, but I know there's at least a few photos of the single-magnet DarkStar floating around. As others have stated, there are two slots for rectangular magnets on the bottom of the bobbin, on either side. Both my '66 and the custom Hammon had a vacant slot, but Hammon was thoughtful enough to take advantage of the vacancy by adding some extra copper shielding tape there. Anyway, I'll look for some photos

 

[fronobulax]

I can't even remember a thread from two years ago

Still hoping for a picture of a one magnet Bisonic.

Also wondering what people expect to happen if a one magnet is converted to two or even a two to a one.

Are we exacting a change in "power" - same thing only louder or softer?

Are we expecting a change in the frequency response - more or less midrange, perhaps?

Are we expecting to notice strings being pulled towards the PU (or no)?

Obviously if Jack and Fred and Curtis and Cordoba Guild did it there must be some benefit to two magnets but what is it?

 

[mellowgerman]

I can't even remember a thread from two years ago

Still hoping for a picture of a one magnet Bisonic.

Also wondering what people expect to happen if a one magnet is converted to two or even a two to a one.

Are we exacting a change in "power" - same thing only louder or softer?

Are we expecting a change in the frequency response - more or less midrange, perhaps?

Are we expecting to notice strings being pulled towards the PU (or no)?

Obviously if Jack and Fred and Curtis and Cordoba Guild did it there must be some benefit to two magnets but what is it?

One definite result of adding the extra magnet results in a larger (and likely somewhat stronger) magnetic field, of which the main benefit would be higher aperture -- sensing a larger portion of the string above the pickup. That will result most notably in a fatter tone with more bass response. Bass response in a bass guitar can often be a sort of perceived volume, but realistically it's not going to get you a louder version of the same exact signal.

A good related example might be Alembic AXY vs. FatBoy pickups. They look the same, but the FatBoy pickups get a physically larger magnet like the Alembic "Series" pickups (of the Series I and Series II basses). The AXY pickups are more common and some people prefer them as they find the bass response of the FatBoy pickups to be overwhelming.

Technically a larger/stronger magnetic field can cause more pull on the strings, but as (I believe) Curtis Novak has mentioned, it can also assist in string vibration, depending on the distance and alignment between strings and pickup/pickup-poles. That makes sense to me... if the strings are passing right through the center of the magnetic field, I would expect there to be a kind of even pull on the string in all directions, but as the string gets closer to the outside of the magnetic field, then I would expect a one-way pull toward the pickup, which would probably kill some sustain.

 

[fronobulax]

One definite result of adding the extra magnet results in a larger (and likely somewhat stronger) magnetic field, of which the main benefit would be higher aperture -- sensing a larger portion of the string above the pickup.

Thanks. That's the concept I was missing.

 

[Mosthigh]

Well, I had to open it up again because I turned the pickup 180 degrees when I put it back in just to see what it would sound like, but it's slightly slanted so the strings were knocking against it on the last 1 or 2 frets. Anyways, here's the pic - just an empty slot for a second magnet.

 

[lungimsam]

Interesting that the housing is designed to receive a second magnet, yet one is not in there.

 

[fronobulax]

Interesting that the housing is designed to receive a second magnet, yet one is not in there.

There has been speculation as to why. Some of the ideas include:

• The second magnet was not having a positive influence on the sound so it was pulled without redesigning.
• Including the second magnet had a manufacturing or materials cost that effected profits.
• The supply of suitable magnets became scarce so only one magnet was installed.
• The housing was designed for a two magnet humbucking pickup that, for whatever reason, was not commercially viable.

I like the possibility that the housing was designed for a humbucker that did not work and so was repurposed as a single magnet bass pickup that was later "improved" by adding the second magnet. The evidence for that is, of course lacking and dissecting original pickups from circa 1964 would shed some light as to whether the earliest production had one or two magnets.