# Math task for cab stackers

Discussion in 'Amps and Cabs [BG]' started by jani_bjorklund, Oct 26, 2002.

1. ### jani_bjorklund

May 22, 2002
Finland
OK. I have a 8 ohm 15" cab. I also have two 10" (8 ohm) beyma speaker elements, a passive 2-way crossover (4000 Hz) and a 8 ohm tweeter lying around. Here is the quest. Can I use the two 8 ohm 10" and the tweeter to build a 2x10" cab wit a tweeter or am I in deep **** impedace wise? By my maths I would end up with one 15" 8 ohm cab and a second cab with a 16 ohm pair of 10" with a 8 ohm tweeter. What will actually happen here?

2. ### GreyBeard

Sep 5, 2002
BARRACKVILLE WV
If you wire the 10" in series and get 16 ohms your X-over is padded for 8 ohms on the low end and the high end as well. The x-over will probably throw more high end current to the tweater than you want and the x-over point of 4k will probably change (although I don't know how but someone will probably quote you a formula explaining this whole thing) because of the different ohms. I once added a Carvin Red Head tweater to a cab . The tweater was a piazo (sp?) type and didn't a x-over. It came with a nice L-Pad and mounted into the cab real nice. Worked really well.

3. ### jani_bjorklund

May 22, 2002
Finland
I forgot to tell I do have two identical crossovers and also two identical horns as well. So I could throw in the second tweeter in series and end up with 2x10" (16 ohms) + 2xtweeter (16 ohms) and a 4000 hz crossover (8 ohms). I guess it would be good to also throw in a pad for the tweter(s). Of course there's also the option to just use one set (1x10" + horn), but would I achive anything with just one 10"?

4. ### Joris

You absolutely MUST use a crossover at its rated impedances. If it says "low 4 ohms" and "high 8 ohms", you MUST hook it up to those impedances. If you don't, the crossover freq will be WAY off. Even worse, you'll end up with different freqs for high and low.