Stacked humbucker bobbins / les paul recording pickups

[JasonG]

HI
I am new here but have been reading up on pickups for a few months now. I have Animal Magnetism for musicians and guitar electronics for musicians so I have some understanding of the basics of pickup winding.
At the moment I am building an updated version of a Les Paul recording. I fell in love with that guitar ages ago and now I want to build one. I have some basic info on the pickups wire gauge , magnet type ect. Now I am having problems finding a stacked humbucker bobbin. Does anyone have a source for those?
Thanks
Jason

[David Schwab]

You can just stick two normal bobbins on top of each other, but you are better off making them since the bobbins in the LPR are rather large in diameter to accommodate the large gauge wire.

You can do them the way Alembic make their stacked pickups. Just get some kind of thin, yet stiff, plastic, like phenolic or even printed circuit board (that's what Alembic uses). You can use the magnet as the core and put a sheet of PCB on top. The LPR had a steel plate between the bobbins. The bottom bobbin also had a magnet, but that's really not needed. The magnets have the South poles facing the steel plate. Alembic pickups have a plastic spacer in place of the bottom magnet.

I've always been a fan of those guitars.

[bbsailor]

You can just stick two normal bobbins on top of each other, but you are better off making them since the bobbins in the LPR are rather large in diameter to accommodate the large gauge wire.

You can do them the way Alembic make their stacked pickups. Just get some kind of thin, yet stiff, plastic, like phenolic or even printed circuit board (that's what Alembic uses). You can use the magnet as the core and put a sheet of PCB on top. The LPR had a steel plate between the bobbins. The bottom bobbin also had a magnet, but that's really not needed. The magnets have the South poles facing the steel plate. Alembic pickups have a plastic spacer in place of the bottom magnet.

I've always been a fan of those guitars.

David and JasonG

You can start with the assumption that the low impedance LPR pickup will have 1/10 the number of turns of AWG 28 to 36 compared to a high impedance pickup with AWG 42/43 wire. If you use a 1 to 10 turns ratio microphone matching transformer, you are looking to make the LPR pickup impedance between 200 to 300 ohms that matches to a transformer with an actual input impedance of about 1500 ohms (rated for 150 to 500 ohms). Putting on more turns, in the 300 to 500 turns range (per coil), will tend to boost the low end a little more. The low impedance LPR resonant peak will be higher than the typical range of the guitar.

The steel plate should be designed to help return the down facing pole magnetic field back up to the strings (U-shaped or channel shaped) to increase the efficiency of the LPR design.

Low impedance pickups offer a different sonic range of guitar tones and less noise. Use the matching transformer at the amp input to keep the guitar cable capacitance effects to a minimum and obtain the full benefit from low impedance pickups. This is fun stuff to play with! Let us know how it works out?

Joseph Rogowski

[David Schwab]

The steel plate should be designed to help return the down facing pole magnetic field back up to the strings (U-shaped or channel shaped) to increase the efficiency of the LPR design.

That's a very good suggestion. I've become very careful about how I set up my magnetic circuits. The right shaped piece of steel used in the right place can make a would of difference.

[JasonG]

First off thanks for the help! I have been bouncing around the net for some time trying to figure out how to get / make some LPR style pickups.
If I were to make bobbins with PCB what kind of glue would you suggest I use and would I wind the coil directly onto the magnet? I think I will use the suggestions of making the 2nd coil and air coil and have a steel plate around the magnet.
As I have said before I am new to all of this. What size magnet(s) would work ? I have heard it was an Alnico magnet the LO Z pickups started being produced in the late 60's so my guess is that they are Alnico 5's.

[JasonG]

So I have wound one air coil and I am tweaking it. Its going in my strat. So far I have made 2 failed pickup winders I had my own designs that didn't work out so well. I have successfully made a tester guitar though!
I ended up buying a LPR pickup and I am glad I did and yes those mothers are heavy.
I have some 36 ga & 38ga, neo bars and mic transformers to play with so I am moving ahead.
I would have more done but, I have been building pedals again and I have had this strange desire to actual play a guitar as a opposed to constantly tweaking it.

[bbsailor]

So I have wound one air coil and I am tweaking it. Its going in my strat. So far I have made 2 failed pickup winders I had my own designs that didn't work out so well. I have successfully made a tester guitar though!
I ended up buying a LPR pickup and I am glad I did and yes those mothers are heavy.
I have some 36 ga & 38ga, neo bars and mic transformers to play with so I am moving ahead.
I would have more done but, I have been building pedals again and I have had this strange desire to actual play a guitar as a opposed to constantly tweaking it.

JasonG,

Now that you have a LPR pickup in hand, I have a few questions.
What is the DC resistance of each coil in the LPR pickup?
Can you measure the inductance of each coil? or both coils in series?
Can you identify the wire gauge used in the LPR pickup?
Can you take the LPR apart and show a picture?

There are a few of us that would find this to be useful information.

Thanks,

Joseph Rogowski

[jonson]

there is a little nick in the back of my mind that keeps saying they were 28aws

[David Schwab]

In the book An Introduction to Scientific Guitar Design, Donald Brosnac says it uses 28 AWG wire.

[salvarsan]

There was a thread on Les Paul Lo-Z pickups at:
http://music-electronics-forum.com/t3737/

Some of the specs were 10.8 ohms DCR and 8mH inductance.
For #28 wire, this puts it in the 300 winds range
at ~165 feet of wire giving a mean wind length of 6-5/8".

This suggests a wider than usual core size, as anyone
who has looked at a Les Paul Low Z pickup can see.

-drh

[JasonG]

Everything sounds right on , my pickup measured at 11.5 DcR
I have some " magnetic paper " so here are some pictures that you may give you a bit more information.
Also if you check out the extras section on the " Les Paul chasing sound " dvd you will see a good shot of " The Log " without pickup covers. You can see both coils of the stacked humbuckers. If those were made before 1965 ( Burns guitars had them by then ) that would make them the first stacked humbuckers ever. I have read on the LPR forum that Chuck Burges has made some repro LPR covers and bobbins and that Les was helping him with the bobbins my guess is that those were the bobbins he was measuring to help out chuck.
I think Chuck has a repair shop (?)in Kalamazoo so if you wanted some of those parts no doubt he has got them. I know he made 300 LPR pickup covers not sure about the bobbins.
On a side note I got Neptue Bound today the Vinnie Bell chapter was mainly just a long list of the people he worked with and a few pic's from his website . The print quality of the book was a bit low but, for 28 bucks it's worth getting. Also they have a picture of Danelectros first pickup winder, I can't see how that thing would work. If you guys have any ideas I would like to hear them.

[David Schwab]

Les made the Log in 1939. I remember reading in Guitar Player that he made the pickups from the coils in an AC powered clock, but I've also read they were hand wound.

Which Burns pickups were stacked?

Thanks for the photos.

[JasonG]

The full story on how the pickups for " The Log " came about can probably only come from the man. Maybe the first pickups on it were from a clock the 2 nd were hand wound who knows. He has said in interviews that he knew about hum bucking techniques and low Z from his understanding of the telephone system. Who knows how many pickups he has had on that thing.
I read that burns had stacked humbuckers. I can't site a source for that but the page is out there, they didn't give a pickup modal name in the article I read. Maybe I shouldn't believe everything I read on the internet. But It does makes sense that we would have stacked humbuckers by the 60's we had humbuckers for a few decades by then some one had to have thought to put the coils on top of each other.
No problem.

[jonson]

the Burns stacked single coils David were the 1965 Bar O Matics with the second coil on a blendable control.

[David Schwab]

the Burns stacked single coils David were the 1965 Bar O Matics with the second coil on a blendable control.

Cool... Burns always did some interesting things... as well as Shergold and Hayman.

I used to have a Hayman 3030H with some really odd Re-An humbuckers. It sounded great once I changed the 100k pots to 500k.

I wish I still had that guitar.