The above photo of the ETB150 was taken from Gibson's Mastertone System for Steel Guitar, 1940. The system consisted of four parts, each part containing 12 instructional pieces of sheet music. To see the entire system of sheet music, please click Gibson sheet music. The interesting fact about most early photos of Gibson instruments and players that you see online or in published books is that the artists, bands or music groups featured were mostly common folks who submitted their photos to Gibson. They were not sponsored by the company. If you are a Gibson fan and notice the same 'old' Gibson photos are posted in several publications at various times, chances are the photos may have come from early Gibson catalogs or music systems.

The above photo and photo to the left show the earliest of bar magnets used in Gibson prewar electrics. Go tofirst Gibson electric and lapsteels, there you will find the complete history of Gibson's pickup evolution. Here in this photo, you will note the similarities of the early lapsteel (rt) and the early ETB (lft). Both instruments have 2 large thick magnets and both have their backs fastened with 12 screws. In late 1938, Gibson devised a more compact, 'horseshoe' shaped pickup which would enable their lapsteels and electric banjos to circumvent the necessity to require full access to the instrument's insides, such as in this photo.

In this photo, note the bar magnet (rt)  is mounted onto a plate and then fastened onto the base of the lapsteel. The bar magnet on the banjo (lft) is not mounted to a plate, but instead is fastened to the underside of the top to the banjo by small silver bar and a small screw. 

The interesting point to the ETB150 is that its early bar magnet ('Charlie Christian' pickup) mounts to the underside of the top of the banjo. The pickup mounts much like the pickups from the famous 1936-'39 ES150, but the magnets are much thicker, more like the early electric hawaiian lapsteels, 1935-'38. 

Another interesting point is there are absolutely no serial/FON numbers on this model, just a simple '23' handwritten on the inside. This factor  makes it almost impossible to date save for the landmarks. 

According to Lynn Wheelwright,

'Gibson began building them(electric banjos) in late '37, probably late Nov of '37 but only shipped a couple before the end of the year by mid Dec.' He estimates that this particular ETB was shipped in the first 5 months of 1938. Mr. Wheelwright has only seen one electric banjo that used the Horseshoe magnet...'is a custom built for Roy Smeck that is unlike any other Gibson ever built and I believe the first electric banjo.' Mr. Wheelwright goes on, 'all the rest have the regular CC with Bar magnets and screw back like yours (this ETB). Even my (Mr. Wheelwright's) 1941 model which was, as I recall one of the last batch.'

I also asked Mr. Wheelwright if he knew how many ETBs were shipped during 1938. He stated,

'Tough question of how many may have been shipped. Bellson's numbers are:

1938: 43 ETB. We found 90 entries but it is very hard to figure how many due to most with no Sn's that could bave been shipped multiple times.'

This photo shows the smooth back of a later '30's model lapsteel (lft) that had the newer, smaller 'horseshoe' magnet. Note the 1936 model on the right requires 12 screws for the back, just like the early tenor banjo. It also requires 4 screws in the middle to elevate and lower the bar magnet pickup. After mid-'38 electric tenor banjos would not use the 12 screw back or the bulky bar magnets.

The above photos are taken from Gibson's Mastertone System For Steel Guitar, 1939. It is a system of 12 individual pieces of sheet music put together into varying degrees of difficulty for the steel guitar learner. The system comes in four individual parts, each part with 12 pieces of sheet music. The parts are colored in peach, blue, magenta and orange. Please see Gibson Music Books 

to view all of the pieces of sheet music.