Ampeg B100R + ext cab?

The B100-R has a 4 ohm speaker and a 4 ohm output impedance. If you wired them in series you would have a 12 ohm load (but it might not be much louder). If you wire them in parallel as is normally done, you will probably damage the amp. I imagine that's why they didn't wire an output jack on it. You could use a 12" extension cab instead of the internal 15", but it might not last very long.

It's a good amp, but it doesn't allow for a lot of changes. Fpr the price of an extension cab you could probably buy another B100r used and run them in parallel (splitting your input signal to both amps with a preamp). I've thought of going that route if I needed more volume.

 

If you are looking for a hifi sound (like a tweeter) you may not have the right amp. These are reputed to have good tone and get loud (as mine does) but it's more of a retro "P-Bass & Flatwounds" tone. I'm not sure if a tweeter would get you there because the 15" may not go high enough to reach where the tweeter starts.

Experiments:

You could use piezo's (no crossover needed + cheap) or a tweeter with a crossover, and the amp should handle that OK without loading the amp down. Just wire a jack on the back.

You might consider making a box the width of the amp and a few inches high to hold the tweeter and then just velcro the box to the top of the amp when you want a tweeter sound.

I tried something like this with piezo's, and found all it did for me was give me clear fret noise.

 

Go to Radio Shack (no tomatoes please), get a non-piezo tweeter with the capacitor on it. The cap is all you need as a crossover. Plug it in and play. I don't know the model numbers on their tweeters, but you can use the horn tweeter or the round plactic one (I don't know if they call it a horn). I've used both and they work fine.

Note: I think the one that looks like a horn has the lowest crossover frequency.

Note 2: Do not bypass the capacitor or the tweeter will fry on the first note.

 

I just noticed that you're from Kansas City. I used to live in Olathe, KS and worked for Payless Cashways in Kansas City before moving to Texas. I love the KC area.

Try the horn out before building an enclosure. Horns do not require an enclosure to function. If you put a grill cloth in front, be aware that it may absorb some of the highs. The material you use will make a difference.

 

I use mine with roundwound-equipped basses like Fender Jazzes, Lakland 55-94, Peavey Cirrus, Zon fretless, etc. and get excellent results though not along the order of an SWR tweeter equipped cab.

Sometimes people tend to forget, we got highs from bass amps for years without tweeters.

Here's an idea, if you must have a tweeter: if you test it with a tweeter and it does give you the sound you want (that's first), why not consider mounting like manufacturers do with coax car speakers? Make some kind of strap that would mount across the opening for the 15 and mount the tweeter on it, in front of the 15.

 

That would be convenient, but I think it would be hard to keep it from rattling and buzzing.

 

I don't think it will block much sound from the 15, but I do think it will be near impossible to keep it from rattling and/or buzzing.

 

If you put it on a sturdy enough brace I can't see why it would buzz or rattle. Use a heavy guage metal for the brace and it should be no problem.