Tweed Princeton-8" or 10" Speaker

[WMThompson]

I'm building a Princeton 5f2-a , and I would like some feedback on
speaker sizes.
I know 8" is stock, but how would a 10" Jensen (or whatever) perform?
How about some pros and cons, and different speaker brands!
Thanks All
WT

[Mark Hammer]

I bought mine in 1976. It is all original with the exception of the speaker. I couldn't get rid of the 8" Jensen it came with fast enough. I replaced it with a JBL 2110, an 8" speaker that I gather is long out of production. The nearest current equivalent to the original stock speaker is a Jensen P8R, with a stated response of 80hz-8khz and a sensitivity of 92.5db. The JBL came with a 60hz-10khz response and a 97db sensitivity. So, the bigger magnet, and lighter more compliant cone gave more oomph per watt and a little more sparkle.

Moving more air, via a 10" cone will certainly deliver more oomph per watt, too. Do take a moment, though, to consider the rated sensitivity. When an amp is capable of delivering 50W or more, what it delivers at 1W can be of considerably less consequence. When you only have 4 or 5 more watts to spare, though, sensitivity ratings start to matter a lot. As a result, if I was asked to choose between a 10" with a 94db sensitivity rating and an 8" with a 97db rating, I'd opt for the latter unless there were something particularly unpleasant about its tonal properties.

In theory, a bigger cone surface will provide more bottom, but a) it has to move to do so , and b) the cabinet can trump the speaker. A "proper" tweed Princeton has a fairly small open-back cab, so differences in bass capability between speakers can often disappear. Similarly, a stiff 10" cone may exhibit less bass response than a more compliant 8".

If the amp is something where the cab dimensions are entirely of your choosing, then certainly you can stretch that puny little 6V6 a lot farther with a 10" and an appropriately-sized cab, factoring in sensitivity. I sometimes run my Princeton through a separate cab, about 30" larger than the amp cab, with a C12R in it. The 12" cone and slightly more closed cab provides more bottom (specs say a 70-6khz range), but with a 93.8db sensitivity, it isn't that different in perceived loudness from the 2110.

[tubeswell]

I built one and use an old 12" Alnico speaker (Goodmans) - works fab.