Disappointed... Jensen P15R too low power

[softwarejanitor]

I was planning on using a vintage 1956 Jensen P15R to build a combo with a 20 watt (2x 6V6) Motorola tube amp chassis but I found out that speaker is only rated at 15 watts...  Dohh!  The original record player console the amp and that speaker came in also had a tweeter, which is probably why Motorola could get away with using that low power handling speaker.  That and the fact that stock that amp chassis (HS-475) is totally clean all the way up to max volume.  I'm modding it to increase the gain and get some overdrive/distortion as a guitar amp though, so that will no longer be true.  A 20 watt guitar signal would probably toast that P15R real quick.

Anyway, instead I will be using a pair of Silvertone labeled Oxford 12" speakers.  I think they are model 12J4-2.  They should be able to handle the power as I think they can handle 15-20 watts each.  Anyone know for sure the rating on these?  I can't find anything specific other than that Fender used the 12J series speakers in some of their smaller combos.

[triode]

Remember, speaker manufacturers used to rate speakers with two ratings, music power and program
power (or some other such name/nomenclature). I would be willing to bet unless you put a bass
on it, it could take 20W from a guitar for quite a while. I would also bet they called it 15W music
power, 30W program (they do this now in fact).

I would use it first and check it out. If you hear flubbing or pole piece slamming, stop and get another
15". Again, I think it could take it. I have an old ampeg in the shop right now that does 30W with a
"15 Watt" Jensen in it. Been in there for decades.

[softwarejanitor]

Remember, speaker manufacturers used to rate speakers with two ratings, music power and program
power (or some other such name/nomenclature). I would be willing to bet unless you put a bass
on it, it could take 20W from a guitar for quite a while. I would also bet they called it 15W music
power, 30W program (they do this now in fact).

I would use it first and check it out. If you hear flubbing or pole piece slamming, stop and get another
15". Again, I think it could take it. I have an old ampeg in the shop right now that does 30W with a
"15 Watt" Jensen in it. Been in there for decades.

You may be right, but I've already got the pair of Oxford 12" speakers, so I think I'd rather be safe than sorry.  I'll probably just build 1 1x15 cabinet for the Jensen and use it with my 5 watt Epiphone Valve Jr.  That little amp shouldn't blow it up too easily.

[Tiny_Daddy]

I have seen vintage speakers just fall apart once the amp is re-built. The ancient adhesives may be long dried up and gone.

[softwarejanitor]

I have seen vintage speakers just fall apart once the amp is re-built. The ancient adhesives may be long dried up and gone.

I think a lot of that may depend on how and where the speaker was stored.  Not only do exposure to light and temperature variations probably play a factor, but from what I've seen there is something in cigarette smoke that causes some kinds of adhesives to break down over time.

FWIW though, I've got a number of 1950s and early 1960s speakers I'm using with tube amps that are working great, so far at least.