Pickup lines

In the first part of our focus on P-90s, we meet with ThroBak’s repro supremo, Jon Gundry, to look at how Gibson’s preeminent single-coil pickup evolved during the 50s and 60s

The earliest P-90 pickups appeared just after the First World War in 1946, having evolved from the short-lived P-13 single-coil variants. Using a plastic bobbin and two Alnico bar magnets, they were wound with 42-gauge plain enamel wire and can be found on a variety of post-war Gibson electric models including lap steels, archtops and solid-bodied guitars. The ensuing success of the P-90 helped to bolster Gibson’s status as a market leader in the new era of electric guitars and it remained the company’s standard pickup until being eclipsed by the PAF humbucker in the late 50s. Nevertheless, testament to its winning design, the P-90 has remained in regular production to this day and is often cited as the pickup of choice for many a guitarist across a diverse range of styles including jazz, blues, rock and punk.

Although its basic construction remains the same, having been in production for well over seven decades, the P-90 has seen many changes with respect to manufacturing techniques and materials – changes that, to many people’s ears, significantly affect both the pickup’s sound and appearance. As such, over the years, guitarists have increasingly turned to period-correct repro P-90s and sought out original examples from the earlier periods of Gibson production for a piece of that elusive vintage magic.

Hoping to arm our readers with some down-to-earth knowledge by shedding some light on the evolution of the P-90 throughout Gibson’s golden era of the 50s and 60s, we spoke to Jon Gundry, founder of Michigan’s preeminent P-90/PAF repro specialists, ThroBak, located in Grand Rapids, some 50 miles north of Gibson’s old Kalamazoo site.

“The initial design appealed to people for good reason,” Jon tells us, “and that design evolved over time because of Gibson’s desire to improve efficiency and I think that’s what drove the evolution of [P-90s]. Those changes inevitably affected the sound, so what I try to do is recreate those variations and elements of the 50s and 60s from ’52 onward. We make every single part of the pickup assembly here in the

USA, and for some of our P-90s, we use one of the original machines with the original fixtures that Gibson used. It’s a Geo Stevens machine made in 1950, so that’s probably a reliable timeline as to when the P-90’s design was finalised.

“As far as the magnets go, P-90s generally have the same ¹/8-inch thick magnets that you see in PAFs, but there was a very small window where they used a thicker [3/16inch] Alnico III magnet. Those sound quite good. They appear randomly during ’52, and you can also find some from ’53. After that, they mainly used Alnico IV, V and II. I’ve seen a pattern of Alnico IV being used for bridge pickups and Alnico II being used for neck pickups, but like many things with vintage guitars, they weren’t consistent about it. By 1960, you often see them with shorter magnets [50s magnets typically measure 2½-inches in length], and by ’61, they became standard. The shorter magnets generally sound a little more aggressive than the longer equivalent Alnico magnets.

“In the 50s, Gibson used the same 42-gauge plain enamel wire you find in PAFs. The general consensus is 10,000 turns, but that varies depending on the era and it’s not unusual to find P-90s well under 10,000 turns. P-90s most often vary between 7.2k and 8.1k[ohms DCR]. You can find outliers above and below, but throughout the 50s they’re generally not as hot as later ones. You see random differences in the ohms [resistance] per foot of the wire and the 42-gauge diameter tolerance. It becomes much more consistent when they go [from plain enamel] to poly-coated wire around ’65 to ’66, but the poly wire really changes the character of the sound.

“The P-90’s character also changes depending on which winding machine was used because of the differences in coil tightness. That really affects the tone. I equate a more compact coil with a crisper treble response in the low-end, which gives a slightly harder tone.”

Guitarist would like to thank Jon Gundry of ThroBak Electronics (https://www.throbak.com)