Choosing a Cabinet

[Steve_77]

I have an Ampeg BA-210 and want to add an additional cabinet. The specs show that the combo alone has 283 watts for the 210, and that an 8 ohm cabinet can be added that will allow the full 450 watts from the amp to be utilized. My question is how to choose the best cabinet to pair with this combo? I am assuming that the 450 watts would be divided evenly between the total of all the speakers between the combo and the added cabinet, i.e. 210 + 210 = 4 speakers / 112.5 per speaker, 210 + 410 = 6 speakers / 75 watts per speaker, 210 + 115 = 3 speakers / 150 watts per speaker, but I don't think it is that simple. I would also assume that there is a point where the higher the number of speakers starts to reduce the optimal performance of each individual speaker at some point, thus losing efficiency. Is there a formula to calculate power handling, and optimal performance always assuming the additional cabinet is rated at 8 ohms? Also, any particular recommendations are welcome.

 

[buldog5151bass]

Traditional/safe advice is to get a matching cab, especially if you like the tone.

 

[Redbrangus]

but I don't think it is that simple.

You're right, it's not. Your mathematical presumption works in the first case -- if you add an 8-ohm 210 cab to your existing speakers, you essentially will have 4 x 16 ohm drivers in parallel, so the power will be distributed equally between the four drivers -- so yes, 112.5 watts per driver. It gets more complicated with the other scenarios you've described -- it really would be best to familiarize yourself with series and parallel circuits to understand why your other calculations don't work. In the 210 +115 scenario, for instance, you'll have three drivers in parallel, but each of the two 10s are 16-ohms and the 15 will be 8-ohms, so yes, it's 4-ohm total load, but the 15 will be dissipating twice as much power as each 10. It could get more complicated yet with a 410 cab in parallel with your existing 210 configuration. As I say, it would be useful for you to understand how series and parallel circuits dissipate power -- it isn't particularly complicated when you're just analyzing speaker impedances. The sticky FAQs at the top of the main page have quite a bit of info about it, and there is a ton of things on the Web about series-parallel circuits.

As far as your extension cab goes, get an 8-ohm 210 and call it done. Anything else either doesn't work or it's too complicated.