Cabinet Building

[Matteo Baratella]

Hello everybody, my name is Matteo Baratella, I am from Italy, I am trying to build my first guitar cabinet for the Marshall AVT150H pre-amp head. (150 watt output - impendence 4/8 ohm).

My cabinet is 70 x 70 x 30 cms = 27,5 x 27,5 x 11,8 inches with a thickness of 1,8 cms = 7,08 inches.

My questions concern which speakers to choose. (I would like 12' speakers)
I would like to mix one 12' Celestion and one 12' Jensen speaker.

Do I have to overcome the watt head output of 150 watts? So, do I have to buy one 80 watt Celestion and one 80 watt Jensen = 160 watt output cabin power (?)

Can I mix these two different brands? How can I know which one will not match with the other?

Do I have to worry about the internal liters of my cabin even if it's an open back cabin?

Thank you for your time
Have a nice day!!
Matteo

[Brian Evans]

I would probably get Celestion G12 or Jensen C12K speakers, rated at 100 watts each. If you get 16 ohm, wire them in parallel for 8 ohms total. If you get 8 ohm wire them in parallel for 4 ohms total. If you get 4 ohm wire them in series for 8 ohms total. I would personally get 16 ohms and wire them for 8 ohms in parallel, but I don't have a great reason why. The interior size of an open cabinet doesn't really matter all that much, what matters more is separating the sound from the back from the sound from the front. If the path is too short you get out of phase sound waves and lose low end response. Open back cabinets often have baffles at the top and bottom to help prevent this.

[Rodger Knox]

good comments above. As far as matching different brands, you need to check the sensitivity rating, which is a measure of how loud the speaker is. It's usually measured in decibels at a distance of one meter with a power of 1 watt. The higher the sensitivity, the louder the speaker will be. A 6 decibel increase sounds twice as loud, so you need to match the sensitivities of the two speakers pretty closely or one will sound louder than the other.