Blues Jr and speaker cabs?

Is it true that a Blues Jr's internal speaker can be disconnected and it can drive a cab? If so, it stands to reason it might gain some volume since it would be moving more air? (thinking of helping it deal with the drums in a finished basement environment) If this is true specific cab suggestions??? Think classic rock and blues etc... with a lil jazz as well. lol

Or would mic'ing it to a PA be a better choice?

Thanks in advance.

I would think that any open back amp could be setup to drive an external cab instead of its internal speaker. I am sure that the Blues Jr. is no exception. Personally, I would suggest a 2x12' vertically oriented cabinet. The added height would also make for better speaker-to-ear dispersion. But, for that matter, have you tried just putting the combo on a chair? It works wonders soemtimes....

Yes, it's true.

Best would be to use a better speaker cabinet and mic that if it needs more volume.

Joe

Look on the back of your amp. If there is a plug for a speaker out and there's currently a line going from the amp to the speaker then you could simply run a line out of that and to a cab instead of to the internal speaker. Just make sure you match the impedance.

The speaker plug is way up in there on a BJ. Just follow the speaker wire up to the plug.

You can always disconnect a combo speaker and use an external cab. (Match impedance) It's just that it's easier to do in some amps than others.

It might. The skinny on speakers vs. volume:

Actual volume is increased by using a MORE EFFICIENT speaker, or by using MORE speakers. Using multiple speakers that are also more efficient will give the loudest results.

Speaker efficiency is rated in db/watt/distance (usually db at one watt at one meter). Some speakers are VERY efficient, like the Vintage 30. The Vintage 30 is so efficient that a 25 W amp on a Vintage 30 will sound as loud as, or even louder, than a 50W amp on another speaker. As a rule, if you drop 3db in sensitivity rating of your speaker, you'll need TWICE the power to get the same actual volume. So, if your BJ has a less efficient internal speaker, and you replace it with a more efficient speaker, it WILL be louder.

When you use multiple drivers, you also increase actual volume. The 'rule of thumb' that I constantly see is that every time you double cone area, you gain 3 db.

So, play along:

If your Blues Jr. puts out 15W and has a speaker with a sensitivity of 97 db (I don't know the actual value, just guessing), and you disconnect it and use a Vintage 30 4x12, then:

You gain 3db with speaker change, and another 6 db going from 1x12 to 4x12, for a theoretical gain of 9 db, which *is* substantial, when you consider that it takes DOUBLE the power to get a 3 db gain.

Will the theory pan out in practice? I can't promise that your BJ will then sound like a 120W amp, but I know it will be louder!

To maximize volume: The most efficient driver, and the most number of drivers that you can live with.

DON'T FORGET: The BJ is a tube amp with an output transformer. You need to match the impedance load to what the output transformer wants to

Hmmm I'm trying to get particulars on the stock speaker as far as sensitivity rating. All I've found thus far is it's a 1 x 12' 8 Ohm Fender Special Design Eminence speaker

As for the rest I just need to be sure the cab has an 8 ohm impedance and more efficient speakers than the stock Eminence which has yet to be properly defined.

Thanks a ton everybody for your responses!

I've played my BJ through Marshall 4x12 slant cabinets in the reheasal studio. Actually it sounds surprisingly good. The output jack is very hard to reach though. Its underneath the chassis next to the output jack that connects to the built-in speaker. Needless to say, don't stick your hand in there when the amp is plugged in...

Depends what you want, do you want volume, band balance or both?

Frank G.