Talking to my friend more, it was actually his grandfather's banjo. His grandfather played rock music on it, in Ireland. It has a Hofner pickup on it. We don't think it's a Hofner banjo, because we cannot find any more like this. And most headstocks on a Hoffner banjo, have Hoffner written on them. Hoping someone out here can help me.
Your friend's banjo was manufactured by Stromberg-Voisinet Co., 316 Union Park Court, Chicago, Illinois. Many of us know this by the shape of the peghead. But, generally speaking, little is known about Stromberg-Voisinet Co. banjos. I won't discuss their pre-history (more later) but the Stromberg-Voisinet Co. that made this banjo was incorporated Feb. 20, 1922 in Illinois. Their factory at 316 Union Park Court was housed in rental space in the large building there. The company existed for almost a decade and in July 1931 the name was changed to the Kay Musical Instrument Co. doing business from the same 316 Union Park Court address The original incorporators were Frank C. Voisinet (wood milling business), Charles G. Stromberg (patentor of mandolin and guitar tuners), and Henry Kuhrmeyer (fresh from the Navy with no apparent experience in musical instrument trade). Generally speaking, the firm's core business practice was to furnish fretted instruments to jobbers and other musical trade institutions. This is why we don't see "Stromberg-Voisinet" branded banjos as the retail market was not the firm's target. Initially the firm concentrated on making mandolins and guitars. I don't think anyone here knows when this S/V Co. began making banjos but my research suggests that they made an open back 17 fret banjo for retailer, Montgomery Ward in or about 1924. By 1926 S/V Co. was making a 17 fret resonator model similar to the subject banjo for Montgomery Ward so we might estimate the date of your friend's banjo at ca. 1926. Also, by mid-1926 S/V Co. was making a 19 fret resonator and flange banjo for jobber/retailer the Wurlitzer company so I would guess the subject banjo was made prior to the Wurlitzer contract banjo. The Kay Musical Instrument Co. (hence S/V Co. by implication) liked to advertise that its antecedents began in 1890 with mandolin maker, Andrew Groehsl, and there is a smidgeon of accuracy to that claim as the original Stromberg-Voisinet Company began with Messrs Voisinet, Stromberg and Groehsl operating as an unincorporated "partnership" of some kind at 3406 Greenview Ave., Chicago, ca. 1920.
Generally speaking, the firm's core business practice was to furnish fretted instruments to jobbers and other musical trade institutions. This is why we don't see "Stromberg-Voisinet" branded banjos as the retail market was not the firm's target. Initially the firm concentrated on making mandolins and guitars.
In my 47 years of being in the music business I have only seen one banjo with a Sttromberg-Voisinet label. It showed up at Goose Acres in Cleveland in the 1980's. Sadly if I have pictures ot the banjo, I have no idea where they are. I remember it was a tenor banjo.
I have seen hundreds of banjos similar to the original posters instrument that had no manufacturer's ID on them.
Almost concurrently with the name change from S/V Co. to the Kay Musical Instrument Co. on July 1, 1931 Henry Kuhrmeyer (now sole owner of the firm) began using his patented neck adjuster system on Kay banjos which consisted in part of a metal rod that replaced the wood dowel. Banjos with the neck adjuster hardware are Kay banjos. However, Kuhrmeyer continued to use the original, and old fashioned S/V Co. peghead shape and other rim and resonator appointments on some of his Kay banjos. So, many early Kay banjos look like S/V Co. products until you find the neck adjuster hardware with the screw in the bottom of the heel facing you. On some of these Kay banjos you might find a paper tag explaining how to use the neck adjuster. Inexplicitly, the paper tag recites the Stromberg-Voisinet Co. name. It is possible that the S/V tag that you saw was one of the Kay neck adjuster explanatory labels? I've attached a photo. Kuhrmeyer, not S/V Co. , is identified as the patentor on the patent application dated April 7, 1930 and the patent was granted granted Oct 31, 1933.
While we're discussing Stromberg-Voisinet Co. banjos here are a couple of inexperienced manufacturing quirks from S/V that had only recently begun manufacturing banjos.
First, SV designed the resonator attachment to be a bolt thru the resonator to a threaded hole in the dowel like the subject banjo. Often the owner would overtighten the bolt to the extent that it would crack the dowel upwards. I suspect that is what occurred with the subject banjo as I detect some metal supports screwed into the sides of the dowel to strengthen and probably straighten it.
Second is a recent ebay offering where SV appears to have copied Gretsch's pot metal tension hoop with an integral armrest that attaches to the pot metal flange. ebay.com/itm/VINTAGE-TENOR-BAN...w3tNfSvER Again, the former owner has overtightened the bracket bolts with disastrous results. This is the first SV banjo I've seen with the tension hoop/armrest combo.
Maybe banjo owners with wrenches can often be a bad combination?
Valuewise, the pickup and the tailpiece are worth more than the banjo. The pickup if its working is probably $65 -$80 and the tailpeice $200 or so on the high end. I would plug that thing in and play rock and roll like his grandpa did. Never heard rock on roll on a tenor banjo, but the way the modern music scene it could use that kind of innovation.
I know nothing about pick-ups, but the tailpiece im,ay not be worth a lot, because it doesn't appear to me to be an original Presto. It's definitely not original to the banjo, and because the uncle lived in Dublin, it's probably a British made knock-off.