Any Attempt at a National/Valco/Supro Under-the-Bridge Pickup?

[Tim Escobedo]

I've played with the idea over the years, but I've never actually seen one apart. Anybody ever attempt one or something similar? If so, any tips?

[Steve A.]

Oops! Wrong pickup...

[Tim Escobedo]

I recall that pickup, but the one I'm referring to is the "Silver Sound" pickup, often mistaken these days for a piezo bridge pickup. When in fact it's a magnetic pickup in the bridge. Patent found here. Looks like a couple small-ish identical hum cancelling coils mounted in the base, in series, with two rod magnets mounted in the saddle portion that extend down into the cores of the coils. I guess somewhat like a moving magnet design. I've heard them briefly a couple times decades ago, thought they were unusual. I recall seeing one with a clear plastic base, revealing to me at the time that it wasn't a piezo. I've been puzzled since then how any meaningful amount of volume could be had from such a passive configuration.

[Steve A.]

I recall that pickup, but the one I'm referring to is the "Silver Sound" pickup, often mistaken these days for a piezo bridge pickup. When in fact it's a magnetic pickup in the bridge. Patent found here. Looks like a couple small-ish identical hum cancelling coils mounted in the base, in series, with two rod magnets mounted in the saddle portion that extend down into the cores of the coils. I guess somewhat like a moving magnet design. I've heard them briefly a couple times decades ago, thought they were unusual. I recall seeing one with a clear plastic base, revealing to me at the time that it wasn't a piezo. I've been puzzled since then how any meaningful amount of volume could be had from such a passive configuration.

Here is a smaller image for display...




And here is a larger image for downloading, etc.



I hope that might jog someone's memory banks!

Steve A.

P.S. Please check back and post whatever you find even if it is nothing in case this thread turns up later in a Google search. Thanks and good luck!

P.P.S. Here is the attached PDF file of the patent for future reference...

US2988946.pdf

https://patents.google.com/patent/US2988946

[Possum]

I made a replica of one once. You have to build everything from scratch. It sounded pretty good, but the amount of time to make one isn't worth the effort. There was some company claiming to sell replicas, but inside the cover they were just a cheap P90. There is a thick piece of steel inside with a right angle bend to it that is hard to get without a huge press. Here's the patent....2,683,388

[LtKojak]

Here's the patent....2,683,388

For the lazy googlers...

https://patents.google.com/patent/US2683388

You're welcome!

[Sweetfinger]

I made a replica of one once. You have to build everything from scratch. It sounded pretty good, but the amount of time to make one isn't worth the effort. There was some company claiming to sell replicas, but inside the cover they were just a cheap P90. There is a thick piece of steel inside with a right angle bend to it that is hard to get without a huge press. Here's the patent....2,683,388

That's not the bridge pickup the OP is talking about.
I have some info from my notes that may be helpful, if a little late...
The two Alnico rod magnets are 3/32" diameter and 3/4" long. They are glued into the wooden bridge saddle with the south end sticking down into the base. Embedded in the base are two small coils wired in series. The DCR for the assembly is 3.58K.
I don't have much in the way of size for the coils. Since they are essentially single pole pickup coils, the turns could be pretty high relative to DCR. They're likely about a half inch in diameter and .2" tall based on my old drawing attempt at "scale". For whatever reason, I did not measure much of the base assembly. YMMV.
If someone really, REALLY needed better specs/measurements, I have of these on a guitar in storage. I could break it out and pull the strings off to get a better look.
It's a usable sound but not "magic", by any means. The big drawback is that it's a lower output and brighter sound than the Valco/Supro pickups which are pretty grunty, I guess you could say. This design would be a better match for some brighter pickups. What I have found is useful on a guitar with one of these is the ability to mix it with the other pickups. On my National you can't do that with the stock 3 way Tele style switch, but just like an old Strat, I can balance the switch in between and get a mix. I've never had the will to actually mod it with a 4, 5, or other way switch.

[Tim Escobedo]

That's not the bridge pickup the OP is talking about.
I have some info from my notes that may be helpful, if a little late...
The two Alnico rod magnets are 3/32" diameter and 3/4" long. They are glued into the wooden bridge saddle with the south end sticking down into the base. Embedded in the base are two small coils wired in series. The DCR for the assembly is 3.58K.
I don't have much in the way of size for the coils. Since they are essentially single pole pickup coils, the turns could be pretty high relative to DCR. They're likely about a half inch in diameter and .2" tall based on my old drawing attempt at "scale". For whatever reason, I did not measure much of the base assembly. YMMV.
If someone really, REALLY needed better specs/measurements, I have of these on a guitar in storage. I could break it out and pull the strings off to get a better look.
It's a usable sound but not "magic", by any means. The big drawback is that it's a lower output and brighter sound than the Valco/Supro pickups which are pretty grunty, I guess you could say. This design would be a better match for some brighter pickups. What I have found is useful on a guitar with one of these is the ability to mix it with the other pickups. On my National you can't do that with the stock 3 way Tele style switch, but just like an old Strat, I can balance the switch in between and get a mix. I've never had the will to actually mod it with a 4, 5, or other way switch.

Thanks much. That's exactly the kind of info I was seeking.

[Mark Hammer]

Hey Tim. Glad to see you're alive and well. When you have a spare moment, pay a visit to the DIYstompbox forum. There's a whole whack of folks for whom the circuitsnippets are a place they love visiting. I'm sure they'd love to hear from you. Though be prepared for the questions!