Tele bridge base plates... why?

[FunkyKikuchiyo]

I was reading in a different thread and a thought struck me. Today we know that the tele bridge pickup base plate gives the pickup a certain sound and it is a must for many people. But, I find it hard to believe that it was implemented to begin with because of the unique sound it imparts. The way we see the designs today the way they were seen sixty years ago are just two different things. The designs on those early Fenders just weren't that meticulous. Why on earth didn't they just thread the forbon and hang it from the bridge as it was? Leo didn't seem overly concerned with shielding (never seen a shielded cable in a Fender prior to the 80s), and the bridge itself would have provided more shielding than he seemed to typically think was necessary. So, it leaves me wondering what the original intent was. Being that the neck pickup was body mounted, maybe he didn't trust the forbon to hold threads?

Maybe it is a stupid question, but I just had a moment where I felt like I was missing something.

[ken]

The bridge plate has three purposes...

1) It is a major part of the bridge grounding system.

2) It is a magnetic focus element for the original spec Alnico III pickup magnets. The plate concentrates the pickup's magnetic field making the pickup brighter and twangier than a pickup without it.

3) Something about eddy currents, I think.

Happy Holidays,
ken

[FunkyKikuchiyo]

See, my problem is that purposes 2 and 3 just wouldn't have been on the minds of anyone at Fender in those days. Those are the sorts of things that happened as happy accidents rather than being strictly intentional. In fact, knowing that Leo typically chased after thinner, brighter sounds he probably would have omitted the base plate if he became fully aware of the sound impact it had. The first purpose is helpful, but seems like they could have run a wire with greater ease than punching out a piece of steel and threading it. My curiosity is what could have been the original motivation.

[belwar]

probably as simple as screws wouldnt stay threaded in forbon, but will in steel.

[big_teee]

I found this explanation on another site.
Later,
Terry

Explained by Bill Lawrence.

Bridge Pickup Base Plates
There is quite some confusion about the Tele bridge base plate. Everybody tries to explain the reason for this baseplate with only one function, but this baseplate has, in reality, 3 different functions:

A. Ferromagnetic functions,

B. Electrodynamic functions

C. All metal plates provide extra shielding.

#1 -- Only the steel baseplates corresponds to function A, B, and C.

#2 -- Brass, copper and aluminum baseplates have no ferromagnetic functions, and therefore, only correspond to function B and C

#3 -- Alloys of the 300 series stainless steels have neither ferromagnetic nor electrodynamic functions and therefore, only correspond to function C.




Brass Base Plate - notice that the base plate also serves as the ground for the bridge pickup.

Function A

Leo Fender used copper-plated steel baseplates on the Tele bridge pickup to stabilize and to increase the magnetic force of the relatively weaker Alnico 3 slugs. The ferromagnetic steel plate increases the inductance of the coil (like increasing the number of turns on the coil).

The steel baseplate also transmits from the steel bridge mount via the steel mounting screws some of the body vibrations into the pickup, resulting in that typical Tele twang. As a negative, this is also the cause of microphonic squealing at high volume levels.

Function B

Baseplates made of steel, copper, brass or aluminum are the cause of eddy current interference. Eddy currents shift the resonances toward the lows, resulting in a fatter, more pleasant tone, especially in the bridge position. If you don’t want to increase the inductance of the coil and the magnetic force of the magnets, aluminum and brass baseplates are ideal to fine tune the tone of single coil pickups.

These baseplates can be very effective on traditional single coil pickups with alnico slugs, but on many different designs, the result can be disastrous.

Also, the thickness of the baseplate is very important -- if the plate is too thin, the effect is very little, but if the plate is too thick, you may end up with a muddy pickup. For excellent results, keep the thickness of the plate between 1/32” and 1/16” and make sure that the plate is firmly attached to the pickup.

[belwar]

The above bill lawrence explaination may scientifically be accurate (i've leave that to scientists) but making the assertion that Leo was thinking about this is just false. There is no way in hell Leo was thinking about stabalizing magnetic fields and increasing inductance and so on. Also, I bet back then no one even thought of eddy currents. Nobody thought about Eddy currents until Joe Gwinn opened his big mouth! <ducking for cover>

Early fender pickups are sloppier than PAF's. Baseplates zinc plated, then copper plated, etc. The magnets were not all Alnico 3, there were other Alnico alloys in there as well (i've done the spectoscopy myself to prove it). The windings are sloppy and all over the place since they didnt have a winding machine at the time. The forbon bottom plates were different thicknesses, and so on and so forth.

I am 100% positive that tonal alteration was not a part of the equation. He probably made the first one and when he tightened the pickup to the bridge the screws popped out of the forbon so he took some of the scrap metal left over from the bridges and and made a baseplate. The bridge and the baseplate are the same alloy (again i've done the spectoscopy myself to prove it).

The name of the game was profit profit profit. If it played it shipped. If they Leo didnt think enough to put a truss rod in the neck, he sure wasnt thinking enough to put a steel baseplate on the pickup to reduce the effects of electromagnetic endopromophic polygonal eddy graphical polymorphs. or whatever

[big_teee]

I think it was the tonal thing!
They may have stumbled on it by accident, but think about it.
A Ash body with a maple neck, can be a pretty unpleasant shrill thing.
Perhaps he stripped the screws from the forbon flatwork, and the quick fix was a piece of metal that was laying around.
Then he may have said "DAMN" That's better Tone.
Lets put sheet metal on the bottom of all of them.
You get a double Dinger.
More durable, and Better Tone!
I think we need to give Leo and the Boys more credit.
It wasn't just bottom line, I still think his objective was to build a good sounding guitar.
Rock On,
Terry

[belwar]

I can agree with that statement. My overall point was that it was likely acidental, or to fix a problem that arose, but not intetionally designed

[the great waldo]

I was just wondering why the tape to insulate the magnets from the base plate was put there , and if it was on the original pickups in the early 50´s
Cheers

Andrew

[FunkyKikuchiyo]

Thanks Belwar, I think you said exactly what I was thinking.

Maybe he did have problems with the forbon threading, and maybe it took one of the other designers later on to convince him that it would be just fine on the strat. That seems like the most plausible explanation at this point.

I'm not sure if I even buy the "happy accident of tone" argument. Many people who worked with Leo said that he tended to really prefer thin, shrill sounds, supposedly because his hearing wasn't all that great. Think of the choice to leave a tone pot off of the bridge pickup on the strat. He figured a bridge pickup should be BRIGHT and why take away from that?

There may be one tonal argument we're overlooking... when the telecaster was designed, spanish guitars were less popular than steel guitars, and perhaps there is some genesis story of it coming from the steel guitar designs or trying to emulate the sound of steel guitars.

[voodoochild]

I was reading in a different thread and a thought struck me. Today we know that the tele bridge pickup base plate gives the pickup a certain sound and it is a must for many people. But, I find it hard to believe that it was implemented to begin with because of the unique sound it imparts. The way we see the designs today the way they were seen sixty years ago are just two different things. The designs on those early Fenders just weren't that meticulous. Why on earth didn't they just thread the forbon and hang it from the bridge as it was? Leo didn't seem overly concerned with shielding (never seen a shielded cable in a Fender prior to the 80s), and the bridge itself would have provided more shielding than he seemed to typically think was necessary. So, it leaves me wondering what the original intent was. Being that the neck pickup was body mounted, maybe he didn't trust the forbon to hold threads?

Maybe it is a stupid question, but I just had a moment where I felt like I was missing something.

I really believe it was for grounding purposes only. All of the other stuff associated with it was more than likely a happy accident.

[ken]

If the Tele pickup's steel plate was only used to keep from ripping the screws out of the Forbon baseplate,
then how come Strats never had a steel baseplate?

ken

[FunkyKikuchiyo]

If the Tele pickup's steel plate was only used to keep from ripping the screws out of the Forbon baseplate,
then how come Strats never had a steel baseplate?

ken

I'm wondering that too, but it should be noted that strats came around years later and had a larger team of designers. I'm not one of the archaeologists, but I believe that while the tele was mainly Leo's design, the strat was more Freddie Tavares and... what was his name? Oh well. Also, if Leo had realized the tonal differences, he'd be more likely to omit the baseplate than to include it as I suggested before. It is probably also why he didn't bother too much with full covers after the tele, but I could be wrong on that.

[Joe Gwinn]

The above bill lawrence explaination may scientifically be accurate (i've leave that to scientists) but making the assertion that Leo was thinking about this is just false. There is no way in hell Leo was thinking about stabalizing magnetic fields and increasing inductance and so on. Also, I bet back then no one even thought of eddy currents. Nobody thought about Eddy currents until Joe Gwinn opened his big mouth! <ducking for cover>

May the Force be against you! -- Heinrich Lenz, 1834

While I did publicize eddy currents and their effects in guitar pickups, I am not convinced that I am the first to understand that eddy currents are important in pickups.

I was not the first engineer or physicist to come through, and some of them must have recalled all those classes about such things. They may have felt that it was too hard to explain, or wanted to keep it a trade secret, or both I suppose.

[big_teee]

I still think that the complexity and the enigineeredness(new word), of the copper clad grounded baseplate was High tech for its day.
I'm all for giving credit where credit was Due!
Hats off for Leo!
Later,
Terry