More turns please

[tonedeciple]

I can only get about 6,500 turns on a humbucker bobbin. This gives me about 6k of DC resistance with 42 awg wire. How can I get more turns to achieve 8k for each bobbin?

[LtKojak]

I can only get about 6,500 turns on a humbucker bobbin. This gives me about 6k of DC resistance with 42 awg wire. How can I get more turns to achieve 8k for each bobbin?

Very simple: using AWG 43 wire.

[Robert M. Martinelli]

Hi,
if your aim is only to achieve an increased DC resistance then the solution Pepe suggested does it twice, as you'll be able to wind more turns of an higher Resistivity wire on the same bobbin.

I understand your aim is to wind a very hot humbucker, but I find that using the DC resistance alone as a key parameter is misleading.

Bill Lawrence once said that trying to judge a pickup on its DC resistance alone is just like trying to state a person's brain by looking at the shoes he's wearing.

The key factor in pickups winding is always Inductance - DC Resistance and stray ( or parasitic ) Capacitance are inevitable "side effects" caused by the wire's Resistivity not being zero.

The basic equations are F0 ( resonant peak ) = 1/(2pi*(Sqrroot(L/C)))

( where F0 is the resonant Frequency in Hertz, L is the pickup's Inductance in Henries and C is the pickup's stray Capacitance in Farads ).

As you can see, DC Resistance does not appear in the above equation ( =it does not affect the resonant peak ).

DC resistance has some relation with the Q factor instead ( or Quality factor )

Q=(1/R)*(Sqrroot(L/C))

The bigger the Q factor, the narrower the pickup's bandwidth ( more "focused" around Fo ).

This comes from this ( approximated ) equation:

BW=F0/Q

Where F0 and Q have the same meaning as before and BW is the bandwidth in Hertz.

An increased DCR makes the divider ( 1/R ) bigger in the Q equation, resulting in a lower Q, this, together with the higher Inductance ( which grows with the number of turns SQUARED ), will most likely result in a hot pickup, at the cost of a very low resonant Frequency and a large bandwidth, so ( all other factors being equal ) it will probably sound loud, but bassy and muddy ( low definition ) with a reduced "attack".

Hope this helps

Best regards

Bob

[Mike Sulzer]

...this, together with the higher Inductance ( which grows with the number of turns SQUARED)....

Increasing the number of turns is what makes the pickup hotter. (Look at the law of magnetic induction.) The voltage only rises linearly with the number of turns, actually somewhat less than that in practice. The rapidly increasing inductance is a problem since it raises the impedance faster than the output increases.

[David Schwab]

All the "hot" pickups use thinner wire, as a necessity, since they have to fit onto the same size bobbins.

So 43 and even 44 are common. To help get around the darker tone you will likely get, many designs switch to ceramic magnets. But the Duncan JB is wound with 44 and uses an alnico magnet. It's not the brightest sounding pickup in the world!

But if you just want to get some more turns than you can with 42, switch to 43 and you will end up with something in the DiMarzio Super Distortion range.

[Robert M. Martinelli]

Increasing the number of turns is what makes the pickup hotter. (Look at the law of magnetic induction.) The voltage only rises linearly with the number of turns, actually somewhat less than that in practice. The rapidly increasing inductance is a problem since it raises the impedance faster than the output increases.

Mike,
I have just re-read my previous post, and I don't think I said something wrong in it..... ( but, if so, I beg your pardon.... )

I was trying to make him understand that DCR is only one of the factors in winding pickups, and that there are no "free lunches", and, all other factors being equal, as the number of turns grows and the pickup gets hotter ( more output ), it also gets darker ( lower F0 ) and less defined ( lower Q ).

I also apologize because my posts often tend to be rather wordy, maybe this is due to my rather poor grasp of the English language that brings me to use too many words to express a concept.

Another factor I didn't mention ( I was afraid to confuse him with too much information at the same time ) is that load ( cable/amp input circuitry ) is a very important factor, as it further shifts the resonant peak and the Q factor on the low side.

Cheers

Bob

[tonedeciple]

Mike,
I also apologize because my posts often tend to be rather wordy, maybe this is due to my rather poor grasp of the English language that brings me to use too many words to express a concept.

Another factor I didn't mention ( I was afraid to confuse him with too much information at the same time ) is that load ( cable/amp input circuitry ) is a very important factor, as it further shifts the resonant peak and the Q factor on the low side.

No apology is necessary. I appreciate your response and the others very much. Thanks. I'm not a mathematician, so I'm a bit fuzzy when it comes to understanding how to figure out the resonant peak, which if I'm not mistaken, is more important than DC resistance.

[Robert M. Martinelli]

Hi td,
Thanks for your appreciation!

The basics of pickup winding ain't rocket science, pickups behave like RLC filters and their equivalent circuit can be drawn with good approximation ( good enough for practical purposes ) as an Inductance with a series Resistance and a parallel Capacitance.

A pickup's frequency response ( signal amplitude vs. frequency ) curve is a "bell-shaped" one, with the vertex at F0 ( resonant peak ) - The Q factor influences the bandwidth ( which turns into different bell widths "graphically speaking" ) - the higher the Q the narrower the "bell".

Each factor has some influence on tone, so winding a good sounding pickup ( or at least one that does more or less what you want it to do ) requires the understanding of how all factors interact ( the above basics ) and, most importantly, good ear and taste.

Hope this helps

Best regards

Bob

[Mike Sulzer]

Mike,
I have just re-read my previous post.......


Bob

Bob

I am sorry to be so abrupt sounding. I just wanted to emphasize in a bit different way that winding more turns on a pickup becomes a problem rather than a solution if you try to take it too far.

Mike

[Robert M. Martinelli]

Oh, Ok Mike, then we're tuned on the same "wavelenght"....

( I told you I had a poor grasp of the English language )

Cheers

Bob

[Mike Sulzer]

Oh, Ok Mike, then we're tuned on the same "wavelenght"....

( I told you I had a poor grasp of the English language )

Cheers

Bob

Your English is great. The problem is my writing!

Mike

[Zhangliqun]

Keep in mind also that 8k worth of 43 gauge is not the same as 8k worth of 42. If you can get 6k worth of 42 on a bobbin, you have pretty close to the equivalent of 8k worth of 43 already in terms of the number of turns. The 6k/42 would likely also be a bit beefier because the coil is probably a bit bigger than an 8k/43 coil.

12k worth of 42 is a plenty hot pickup. You might even end up removing a few turns.

Another way to handle the situation is to make your own taller bobbins. Cut a bobbin in half and crazy glue a 1/4" wide strip of styrene (thanks again, Spence) as an insert to make the bobbin taller. There are limits to this too, of course, because it pushes the magnet farther away from the strings by necessity, but 8mm tall bobbins are very viable in my experience (vs. standard +/-6.5mm).

[tonedeciple]

12k worth of 42 is a plenty hot pickup. You might even end up removing a few turns.

I have to admit my intention now, after reading all the excellent responses to my question, is not to actually wind an 8k bobbin. As I was winding up my first pair of humbuckers last week, I managed a maximum of 6,100 turns, which filled one of the bobbins. That got me to thinking about how other winders are able to get 8k and more from a single bobbin. In truth, I couldn't be happier with what I ended up with. As it turned out, the DC resistance measured 9.6k for the bridge and 6.8 for the neck.

I've tried high powered pups before, but IMO, they drive my amps too hard. Even my 15-year old son seems to prefer a lower powered pup. After all he just asked me to wind a vintage style P90!

[belwar]

myself I think low powered pups in the 7k range are just perfect.. You can do way more with that P/U than something that is 10-15k. There is something just sweet around 7-7.7k

[Jim Darr]

Belwar hit the nail on the head!!

Jim