potting. time, type and tone.

[GunbarrelCustom]

I wound a P-90 neck for my hand made LP, a dog-ear P-90 for my hand made LP Jr double cut and a humbucker for a tele I made. I went to a 5 hour jam today and all three were really great sounding and really took my guitars even further. I am excited to wind a bridge P-90 for my carve top when my mojotone order arrives in a few days. I did not pot the humbucker and since I do not have proper coil tape, I used teflon plumbers tape, and feedback was not a problem! Really the only one that was any trouble was the neck P-90 when using fuzz through a cranked amp. Maybe I was just lucky or maybe I just have a knack for winding pickups as even the regulars at the jam commented on my tone today.

I did try and pot the P-90s though due to not having a thermometer I only left them in the wax for a bit over a minute fearing the pickup melting and also worried about having muddy pickups from over potting them. I have a thermometer on the way and will give it another try later this week.

My questions are:
1) I am using the traditional 80/20 paraffin/beeswax mixture. How long should I leave the pickups in the hot wax bath without changing the tone from too much wax? I have seen 10-20 minutes suggested or until the air bubbles stop coming out of the pickup. Is this correct? I do want to maintain the "good" microphonics.
2) For non-butrate pickup coils what temperature should I shoot for? Is it true that hotter wax is what causes tone change?

Thanks for all the help!

[big_teee]

Hi Gun Barrel:
Potting is something you pretty much do, or you don't do.
It is hard to pot just a little bit.
On gibson type pickups if you wind with good tension and tape the coils well, you may not need potting.
If you are winding just for yourself and like the way the pickup sounds unpotted You probably want to leave them alone.
If you play with lots of gain or sell pickups then you probably want to pot them.
Tele bridge pickups with steel baseplates need potting.
Most pickups with covers need potting.
I use a big cooking thermometer and try to keep the heat in the 130-145F degree range.
I pot for 10-15 minutes.
I shake the pickup a couple of times in the wax and when the bubbles are gone, I take them out.
On Humbucker pickups with covers, I like to tape them good, and solder on the cover.
I wax pot with the covers on and while they are hot I drain all the hot wax out the corners that will run out.
The tape protects the bobbins, and the wax eliminates the microphonics caused by the cover contact with the internal pickup parts.
On vintage PAF and P90s, they were taped and left unpotted.
I pot all pickups that I leave here.
a 80/20 wax mix is fine.
I start with gulf canning wax and thin to my liking.
Lots of variations in hand winding.
You will learn to do the things you like, and that work for you.
Others feel free to add your suggestions.
Good Luck,
T

[SonnyW]

My questions are:
1) I am using the traditional 80/20 paraffin/beeswax mixture. How long should I leave the pickups in the hot wax bath without changing the tone from too much wax? I have seen 10-20 minutes suggested or until the air bubbles stop coming out of the pickup. Is this correct? I do want to maintain the "good" microphonics.
2) For non-butrate pickup coils what temperature should I shoot for? Is it true that hotter wax is what causes tone change?

Thanks for all the help!

First off, like BigTeee said, it is hard to pot a pickup just a little bit. IMO, the microphonics are coming from two sources. One would be from the windings themselves vibrating and changing their internal distributed capacitance a tiny amount, similar to how a condenser mic. works. The other is on pickups with a metal cover and the cover vibrating. So on your P-90's just about any potting that you do is going to stop the windings from vibrating much. By the time you leave the pickup in the wax long enough to get the pickup hot enough that it will start to soak in and won't just build up a layer of wax on the surface, it is going to start penetrating the coil. If you want to pot "just a little bit", one thing you can try if you have access to a heat gun or a hair dryer, (and I have tried this with some success) is to drip just a few drops of wax on the edge of the winding either with a spoon or from a candle, and then heat it with the heat gun just enough to let it soak in. Do that on both sides, and you are done.

My experience with the 80-20 paraffin/beeswax mixture is that it is going to melt at a certain temperature that depends on the wax you get. For my mix it is around 145-150. But if you get a different batch of paraffin next time it may be a different melting temperature for the same ratio. Also as the wax melts it goes through a sequence when you are heating it up. I have a precision thermometer installed on my wax pot and I can see this happening. The temperature will rise until it gets to a little more than the melting point of the wax, and then it will hold fairly steady as the wax melts. As long as there is some wax in the pot that isn't melted yet the temperature will hold. But after the last bit of the wax melts then the temperature will begin to rise. So if there is enough room in your wax pot you can start potting and be somewhat sure that it won't get too hot as long as there is some unmelted wax in the pot.

On the ABS bobbins, they can stand up to maybe 160F without a problem. You can pot them just about any way you like. On butyrate bobbins it is never a good idea to pot them, unless maybe you might use the method I described above with the drips of wax and a heat gun, but even that is going to be tricky. The butyrate plastic will begin to warp at around 140 degrees F. Gibson never potted their P.A.F.'s or the original P-90's and I'd bet that is one of several reasons why they didn't.

As far as potting changing the tone, yes IMO it does to some extent. I measure the resonant frequency of all my pickups. If I measure it before potting, and then again after potting and letting it return to room temperature, the resonant frequency will usually drop, sometimes as much as 1kHz. That means the potting makes the pickup a bit darker, at least in theory. Whether it is enough to worry about or not is a matter of opinion. I don't think it makes enough difference for me personally to hear, but there are plenty of people with better ears than mine. Just my $.02 on all of this.

[GunbarrelCustom]

Thanks! Since I still do not have coil tape I used Teflon plumbers tape on the humbucker coils. I squeezed the cover tight when soldering it on and even at loud volume with fuzz it was never uncontrollable!

I asked about time in the wax as the two winders I really liked claim to "flash pot" the pickups to get rid of the bad microphonics while keeping the good. The pickups are really lively and generally do not cause problems while playing.

It is interesting that wax keeps the same temp until it is all melted. Water does the same both from solid to liquid and liquid to gas. The latter is how rice cookers know when to shut off. I did get an inexpensive 1.5 quart crok pot to melt the wax and the thermometer should arrive tomorrow. We have a gas stove and I don't want a fire!