The main part of this little tone beast is the 1956 Jensen P12RC Professional Series speaker, that I got on eBay a few years ago. The speaker was not advertised correctly and didn’t have any of the #’s on the frame in the description. I had no idea what model the speaker was. The poor soul who sold it didn’t answer any of my emails, or anyone else’s either I assume, which is why I won the auction for all of $16 + shipping! His loss, my gain! I had no idea what it was until I opened the box and saw a mint condition P12RC. The speaker looked like brand new right out of the box. I got lucky for once in my life! BOING!!!!
Previous to this speaker, I had tried a vintage P12S, and P12Q Jensen’s, and a couple other oddball speakers in it as well as the stock speaker. One note was all I needed to blow into this speaker to know that this was the speaker I had been looking for. This speaker blew the other 2 Jensen’s I tried previously, right out of the cabinet. No comparison at all. It had more volume, and it’s tone was about as sweet as it gets. The previous two Jensen’s actually didn’t sound too bad tone wise, but the amp had less volume and sounded thin. This Pro Series Jensen speaker has the best tone for harp that I’ve ever heard from a vintage Jensen. The volume about doubled from the other Jensen’s as well, indicating that it is more efficient than the others I tried.
As I do with anything that delivers great harp tone, I tried to get all the info that I could about these Pro Series speakers from anyone who knows about why these speakers sound good. Any factual information about them, but nobody has been able to tell me much about these speakers other than not many were made, and that they were only made for a couple of years. I don’t even know how true this is. The speaker has a bronze colored frame and is the typical looking vintage Jensen basket frame, alnico magnet and a strange looking see through dust cap about the size of a quarter. The dust cap appears to be half paper, and the center is what looks to be a very fine cloth mesh. I had previously thought it was possibly brass mesh, but closer inspection with a magnifying glass shows that it is finely woven cloth.
The sticker on the magnet frame is chrome, black and red. It says, “Jensen Professional Series Speaker”, “Specially Designed for Industrial, Commercial, and Institutional Use”. The #’s on the frame are P12RC-C6160 220641. I’d like to know what makes this speaker different from the regular vintage Jensen speakers. If anyone has any accurate information about these speakers, I’d really love to hear from you. About all I know about it is that it was likely made for a juke box or some other commercial use which would explain why it’s more efficient than the standard series speakers. It needed to be louder in a commercial setting.
Anyway, I was close to giving up on my Blues Jr. until I put this speaker in it and got the mod’s right. All I can say now is, “WOW”! I knew this amp had good potential, and it turned out to be even better than I ever expected. It’s by far the best tone I’ve ever heard from an amp of this size and wattage. It’s not necessary to have one of these Pro Series Jensen’s to greatly improve the tone of the amp. I have installed a few regular vintage P12R’s in other Blues Junior’s that I’ve worked on, and they do sound very good as well, but not quite as good as the Pro Series model. I would highly recommend any Blues Junior owner who wants to use the amp for harp to install a vintage Jensen P12R in place of the stock speaker. The stock
I would recommend that you DO NOT use a P12S or a P12Q either. The P12R is perfect for the 15 watt amp. I plan to have a custom cabinet made for my Blues Jr. that is slightly oversized to get the most out the 12″ speaker, and have it made from real wood. I can’t imagine why Fender used compressed paperboard or whatever it is for these and some of the other amps they made that could have really benefited from a well made wood cabinet. Must have been $$$.