Butyrate Bobbins

LP1865

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What are these? Do they affect tone? How are they different from normal plastic bobbins found in other pickups?
 

cooljuk

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Cellulose acetate butyrate (CAB) is a type of plastic used in manufacturing injection molded parts. The type of plastic doesn't matter as much as the internal shape/size of the bobbin, and almost all of the butyrate bobbins I've seen in repairs are NOT the correct shape/size for PAFs, anyway. Even when they are correct, if the builder doesn't put the coils on right, it messes up the coil geometry.

To me, it's kinda like DCR. The misinformed pickup buying majority is fascinated or even obsessed with it, so I list it in my specs, even though I know it's a pretty insignificant factor compared to much more important things.
 

cooljuk

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The plastic is used in lots of things, in industry. It's somewhat soft. The "rubber" handles on your pliers are likely some type of butyrate. Screwdriver handles were commonly butyrate, but now are generally stiffer plastic that lasts longer. If you get tools and blades resharpened by a professional, they will likely come back dripped in a protective butyrate coating. If you ever had a "stinky screwdriver" (that sounds like a drink) it's because of the chemicals gassing off of the CAB handle. Same reason some Fenders stink, when you open the case.

The reason people advertise butyrate bobbins on humbuckers, is the same reason they advertise maple spacers. Though those materials are technically inferior to many other modern alternatives, it's what Gibson used on PAFs in the late 1950's and early 1960's - therefore, much like Bumblebee capacitors, making an inferior product the absolute apple of the modern player's eye.

Now, there could be some minor reasons to want to use Butyrate in a real true PAF replica. The bobbins will warp and twist and crack and sink in like the originals. Could make the look, or even the sound, accurate that final half of a percent. ...but the thing is, most replicas have some real glaring obvious deficiencies in accuracy in construction that make that last half a percent in looks or sound irrelevant. It's mostly just a "because Gibson did it" thing, like Bumblebee caps, paper tape, black coil hookup wires, and maple spacers. None of that really matters in a significant way. ...but it's what folks (self included on a really true otherwise accurate replica) want to see.
 

somebodyelseuk

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Funny you say about warping etc bobbins. I'm very much an amateur tinkerer, using budget pickups for my experiments.
Couple of years ago, I decided to play around with magnets, and tried to 'depot' my guinea pigs. Of course, should have known it's virtually impossible to do, because of surface tension and capillary action, but anyway, threw em in the oven. Slightly too hot, bobbins softened just enough to sag a little bit. Miraculously, pickups still workand actually sound clearer. Temp was maybe 80C, so combination of bobin deformation and wire expanding, contracting changing tension???
I'd place it in the 'don't try this at home catagory.
By the way, bought your book last Christmas. Fascinating read. Just started rereading it.
 

LP1865

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Now, there could be some minor reasons to want to use Butyrate in a real true PAF replica. The bobbins will warp and twist and crack and sink in like the originals. Could make the look, or even the sound, accurate that final half of a percent. ...but the thing is, most replicas have some real glaring obvious deficiencies in accuracy in construction that make that last half a percent in looks or sound irrelevant. It's mostly just a "because Gibson did it" thing, like Bumblebee caps, paper tape, black coil hookup wires, and maple spacers. None of that really matters in a significant way. ...but it's what folks (self included on a really true otherwise accurate replica) want to see.
Thanks!
I wasn't even considering PAF replicas.
 

cooljuk

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Funny you say about warping etc bobbins. I'm very much an amateur tinkerer, using budget pickups for my experiments.
Couple of years ago, I decided to play around with magnets, and tried to 'depot' my guinea pigs. Of course, should have known it's virtually impossible to do, because of surface tension and capillary action, but anyway, threw em in the oven. Slightly too hot, bobbins softened just enough to sag a little bit. Miraculously, pickups still workand actually sound clearer. Temp was maybe 80C, so combination of bobin deformation and wire expanding, contracting changing tension???
I'd place it in the 'don't try this at home catagory.
By the way, bought your book last Christmas. Fascinating read. Just started rereading it.
I'm really glad you enjoyed the book!

You may not like my answer but the two most likely reasons your pickups sounded different after your oven experiment are:

1) Something else unrelated to the oven baking changed. Perhaps, you also changed the strings while you did this. Maybe you installed the pickups back in the guitar with a quarter or half turn of the mounting / height screws different from when they came out? Maybe even if they were installed to a measured distance from the strings both times, they just sit at ever so slightly different of an angle now, tilted forward or back a little, shifted 1/16" to the side one way or another, etc. That stuff is all more significant of a difference in sound than "some wax" verses "some more wax" in the coils.

2) Your mind is messing with you. Lots of scientific experiments with tight controlled situations have been done on A/B listening and they all show that even just a very short, even minutes or less, of difference between listening to A and B will allow your brain to distort the reality of what you heard. To do an objective listening A/B comparison, one really must listen back-to-back in a blind experiment.

I don't recall if I mentioned the details of this in my book but, the way I do this (and A/B comparisons are a huge part of what I do), is to record the different examples in as tightly controlled situation as I possibly can, then export the various clips to listen to and name them accordingly. I'll load them all into a playlist in iTunes or something similar, with multiples of each one sometimes, and shuffle them, taking notes as I listen but without looking at which clip I'm hearing. Then, I go back and compare my notes to my play history, which is the first time I know what clips I've been taking notes on. If I'm iffy on the results or things are very close, I'll shelve the entire project for a couple days and do it again, playing back on a different familiar system and take new notes, adding them all up in the end. This is a pretty objective way for a single person to do such a thing.
 

somebodyelseuk

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Hey J.
As I said, I don't believe you can de-pot a pickup without stripping the wire coating, and i think we agree potting is like pregnancy - it either is or isn't.
In terms of the result, and bear in mind these are not PAF repros, just cheap humbuckers, I take on board the adjustment effects and the scientific testing. I was a chemist for a chemical company before my eyes went bad, so when it comes to scientific analysis... If it wasn't for the eyes, I'd have bought a winder and had a room full of dud coils, by now.
 

ARandall

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I think James did a destructive experiment......tried to de-pot then cut the wire off the bobbin to see how successful it was. He can correct me if I'm wrong, but it was perhaps 5% of the wax in there that was removed.
 

LP1865

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Where can I get this book?
Everyone seems to be talking about it.
 

somebodyelseuk

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Where can I get this book?
Everyone seems to be talking about it.
I got mine from Amazon, "PAF Humbucker Pickup. From Myth To Reality".

Yeah, the depotting thing, simple physics, really.... I should have realised before I even tried. In my old job, we used a vacuum oven for drying tricky projects, however that's just water. Basically, a vacuum oven drastically lowers the boiling point of the liquid and draws the moisture out. What that would do to the flashpoint of the potting wax...?
My observation of my result.... I knew it was nothing to do with wax - it's either potted or it isn't, lightly potted is just marketting BS. My coils had sagged. I was going to just bin em and get another pickup. I was in the middle of ordering when it occured to me to check them with a meter. I'd expected the wire might have fractured, but I got a good reading, so thought what the hell. I expected them to sound like crap, if they actually worked at all.
 


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