200 watts at 8ohms=400 watts at 4 ohms? am i getting this right?

henfjel · #1 08-25-2011, 05:44 PM

well, to elaborate on that a bit:
i have a tc electronic BH500 head. as of yet i have not bought a cab but i just have one question here. one cab i'm looking at is rated at 200w at 8 ohms. so, does this mean that the cab can take 400w at 4 ohms?
i've gotta admit, i'm not really getting this wattage/ohm thing so please enlighten me if this is totally wrong.

thanks,
henfjel

JackTheRipper · #2 08-25-2011, 05:48 PM

No, that is totally wrong. Here, read the AMPS FAQ!! Info on OHMS, Allsize RIGS-OverUnderPowerCabs DIY TechTalk-Links

--jack

5StringBlues · #3 08-25-2011, 05:48 PM

^ Yup,read the FAQ.

The ohms won't go down to 4 unless you add a second 8 ohm cab.

8 ohm cab + 8 ohm cab = 4 ohm load. The ohmage of the cab doesnt change,the load you put on your head does.

JHAz · #4 08-25-2011, 05:50 PM

no. The cab is 8 ohms, and will never be 4 ohms (nominally). Your amp will see an 8 ohm load, and it's 4 ohm capability is not relevant.

Simplistically, if you set up your system with an 8 ohm cab, then disconnect it and connect a 4 ohm cab, without changing anything else, the 4 ohm cab will draw twice as much power from the amp. Real world amps do not double their maximum power when you halve the impedance they are driving, but as long as you are not at the bleeding edge of the amp's power capability, power doubles when you cut the impedance in half. It's Ohm's law.

henfjel · #5 08-25-2011, 05:51 PM

ok, thanks for clearing that up!
i think i just might buy one or two tc bc210 cabs that the manual says i can use.

another question then:
how much noticeable louder will a 212 cab be compared to a 210? will i be able to tell the difference?

BurningSkies · #6 08-25-2011, 06:51 PM

Quote:

Originally Posted by henfjel

ok, thanks for clearing that up!
i think i just might buy one or two tc bc210 cabs that the manual says i can use.

another question then:
how much noticeable louder will a 212 cab be compared to a 210? will i be able to tell the difference?

Generally speaking, you can assume that the 212 will be louder than the 210. 12" speakers have more cone area than 10" speakers, thus more air pushed, more volume. That's rough look at things though, because it doesn't take into account excursion, or the distance a given speaker can travel...more excursion, more air moved, more volume. If we're looking at speakers with similar excursion, that are either 10 or 12 inches, I'd go with the 12's if you're concerned with volume from a single cab.

And on a side note, you may wish to view TC's amp wattage ratings with a grain of salt.

henfjel · #7 08-26-2011, 07:54 AM

Quote:

Originally Posted by BurningSkies

Generally speaking, you can assume that the 212 will be louder than the 210. 12" speakers have more cone area than 10" speakers, thus more air pushed, more volume. That's rough look at things though, because it doesn't take into account excursion, or the distance a given speaker can travel...more excursion, more air moved, more volume. If we're looking at speakers with similar excursion, that are either 10 or 12 inches, I'd go with the 12's if you're concerned with volume from a single cab.

And on a side note, you may wish to view TC's amp wattage ratings with a grain of salt.

ok. i'll have to consider it then, and put some thought into it before i decide.

yeah, i read that. it kinda sucks, the info being wrong like that but it does not really matter that much to me. the amp sounds great (i don't mind the compression thing) and by norway standards, the price was low.