Seeking info about a 1933 "All Electric Dobro" pickup -it's particularly noisy

[David King]

My good friend is restoring this particular guitar and wonders if there is a remedy to it's noise. I suspect it's not a terribly efficient pickup and since there's no shielding it buzzes louder than most. I was wondering if perhaps a dummy coil could be added to the circuit but would need to know the approximate turns*area of the existing coil. I'll see the instrument in question and take a few photos later on today.
I'll bet that there were fewer sources of EM noise in 1933 than there are now.

Here's a photo of the pickup on an 1934: https://images.reverb.com/image/uplo...fvkyfveohl.jpg
It appears to be a split coil?!!

[Lollar Jason]

consider there is probably a spider under the cover plate being a dobro. I have never seen that set up but have seen alot of 30s lap steels- national aluminum pans with split blades like that Also some gibson steels. They must have split the blade because they are using a horseshoe magnet so the split minimises the cancelling between north and south. For those that just follow what the pickup books say- Yes a single coil that has north polarity on one end and south on the other works with some problems in the very center of the coil- its not humcancelling. I imagine DK knows this im just saying for someone else reading. Typically those pickups used 38 gauge and would be around 1.6K oms- big coils though so I dont know whats up with the spider. A couple of those old under the bridge pickups used tiny coils but ive only seen 2 or 3 of those in the last 25 years where the big 38 gauge coils are common. Another thing I have run across is some of the very early old amps had a different input impedance and if you plug a strat or some such thing in they distort to an extreme.
adding a photo of a single coil with two polarities the magnet is a channel horseshoe

[Mark Hammer]

I doubt it was original, but a local guy asked me to repair a 1948 DeArmond for him (I may well have mentioned it here in past) that was installed on a dobro of what I gather was similar vintage. The DeArmond was one of these and has two Alnico mags inside, separated by a brass spacer. One of the mags lies under the 4 lowest strings, and the other lies under the high E, with the brass spacer below the B. Ferromagnetic "tongues" sit atop the mags, extending the field a little outwards. The separation of the two mags is, I gather, a strategy for fostering equal sensitivity to the G, B and high E, given the gauge of strings typically used at the time. I imagine the unusual blade in the pickup David notes employs a similar sort of strategy to foster similar sensitivity across strings. I guess we always need to keep in mind that such pickups were devised well before we had adjustable polepieces, or even height-adjustments at the high and low E sides of the pickup mounting ring. Moreover, one always needs to be mindful of what sorts, gauges, and compositions of strings were typically being used when such pickups were being developed.