Dating standel amplifiers
The SPL rating specifies how loud a speaker is at a distance of one meter when driven by one watt. I don’t know what speaker is in your amp, and even if I did, its specs might not be available.
That’s probably a moot point, though—experience tells me that most original speakers in amps of that age are substantially fatigued and generally sound very weak. It's a great-sounding speaker, but with a sensitivity rating of 100 d B, it’s relatively efficient and would probably be pretty loud in that amp.
Here’s a list of brands along with their EIA codes.
(I’ve also included a few others brands you might encounter as aftermarket installations.) This should help you identify your speaker.
If you want the least volume from your amp, search for a speaker in the style you like with the lowest SPL rating.The Statler Brothers were planning to produce and distribute them as, "Diamond T" guitars, from their location in Staunton, VA, however after showing some of them at the NAMM show for music dealers, the product line did not significantly make it to the market place. the cool headstock is a major rercognizable feature. The case is velvet lined and is in pretty good condition. Years later, on their popular TNN television show, they did not even play them. Were you ever able to find out anything about this guitar? David Bowie played a jumbo shaped 12 string on the ziggy tour/film, and demo recordings. I have a dreadnaught shaped 12 string with a Harptone logo and a standel logo visible under the paint. I collect them and also collect photos and serial numbers for a web page data base. The guitar has all the hardware but one machine screw to hold together a pin and gear for tightening the string. You also mentioned that you’re looking for a speaker option that decreases the overall volume of your amp.You need a speaker with a lower audio output, so you should consider the spec known as SPL, or sound pressure level (sometimes called sensitivity).