# How many ohms would this be?

Discussion in 'Amps and Cabs [BG]' started by B String, Aug 1, 2004.

1. ### B StringSupporting Member

Apr 11, 2002
Los Angeles
What would 5.3 ohms and 8ohms, come out
to be? Wondering if i could still use a 4ohm
minimum amp, or if i need a 2ohm minimum amp.

2. ### xcental34x

Feb 28, 2003
Memphrica, TN
It'd be less than 4 ohms. You need a 2 ohm minimum. 8 + 8 ohms= 4 ohms, so obviously 5.3 + 8 would be less. I'd take a wild guess and say it'd be 3.

3. ### bennettsteveGuest

Dec 14, 2002
Good guess! It would be approximately 3.2 Ohms.

4. ### blueflamerick

Jul 1, 2004
Richmond VA
Right. To figure this out in the future, multiply the 2 resistances then divide that by the sum of the resistances:

8 * 5.3
________ = 3.1879699

8 + 5.3

5. ### xcental34x

Feb 28, 2003
Memphrica, TN
Woohoo! I rule!

6. ### B StringSupporting Member

Apr 11, 2002
Los Angeles
Hey... you guys is smart! thanks!

7. ### De Teng

Oct 27, 2003
Utrecht, Holland
The exact formula is in fact this one:

1/R(total) = 1/R1 + 1/R2 + ..etc..

Now you can always do the ohm job yourself.

8. ### IvanMikePlayer Characters fear me...Supporting Member

Nov 10, 2002
Middletown CT, USA
by the way.....................

don't do it.............you won't even hear the 8 ohm cabinet, the 5.3 ohm cabinet will get most of the juice, so unless the 8 ohm cabinet is at least 3 dB more sensitive, it won't sound like much if you have them both on the same load

on the other hand, if you have them on opposite channels of a stereo rig with seperate level controls, no problemo

9. ### BasspolizeiPseudo bass player/collector

Jun 23, 2004
US
Buy basses and lots of guns before it's too late! You have been warned.
If and when you sell, buy matching OHM Ampeg gear and be happy for life! Enjoy..........

10. ### De Teng

Oct 27, 2003
Utrecht, Holland
Good point dude...I just forgot! A small example to understand a bit more of the power/ohm blabla.

For instance... using a 2.10" and a 4.10", you'll have to choose the 2.10" with twice the resistance of the 4.10". The 2.10" will get then half the power but also has half the amount of speakers. If they are from the same brand (and most of the characteristics resemble in general) then you have the same power to every speaker.

Example, hypthetically speaking

600W ... in a 4 ohm and an 8 ohm cab.

The 4ohm gets twice the power than the 8 ohm. Thus 4 ohm > 400W and 8 ohm > 200W. The 4 ohm (4.10) gets 100W a speaker and the 8 ohm too (which was 2.10 remember?)

(That's why I want a Bag End 4 ohm 2.10" in the future, so I can wire it to 16 ohm -speakers in series instead of parallel- and use it with the 8 ohm 4.10".... awesome sound and still managable!!!)

11. ### B StringSupporting Member

Apr 11, 2002
Los Angeles
AARRGH!! Just when I think i've got it figured
out, you guys come up with logic! DAMN!!
So the idea of adding an 8ohm 112 box to the
5.2 ohm 310 box won't work well? I can't always
carry tons of gear to gigs, but when i need more,
I like having things modular. Now I'm back to square
uno!

12. ### De Teng

Oct 27, 2003
Utrecht, Holland
In theorie...no...but it depends on how you think about it. Just listen to it, but I can't garantee you satisfaction.

13. ### BassIan

Apr 27, 2003
Cupertino, California
This may not be exactly as you expect. Right now I have a 4-ohm SWR Goliath Senior in parallel with an 8-ohm SWR Big Ben. Both of them get similar levels, particularily when I open the amp up a bit, then the 18 really gets going, which I actually really like. So, it's at least worth a try. Cabinet sensitivity really comes into play. In my setup, the Big Ben gets half the power of the Senior, but seems to be more sensitive, which makes up for the power difference.

14. ### De Teng

Oct 27, 2003
Utrecht, Holland
It depends on the total square inches of the speaker too. An 18" has a lot more than a 10"... together with the fact it is more sensibel, he comes (as shows) pretty close a 4.10" which gets more power.

In my example, I didn't want to mention it, because it makes it even more complex. But in fact, it is very important. My excuses...

So we have now a few variables:

Total impedance thus power each speaker
Sensibility
Total square inches

(complex isn't it..??)

15. ### B StringSupporting Member

Apr 11, 2002
Los Angeles
was hard enough!

16. ### BassIan

Apr 27, 2003
Cupertino, California
Speaker area has little to do with anything in the real world. Besides, 6 10" speakers have nearly twice the surface area of 1 18" speaker...

There are too many factors to consider, but a very useful one is the sensitivity rating of a cabinet, assuming you know all useful parameters (power applied, frequency of test signal, distance of measuring device from baffle or dust cover, etc).

17. ### B StringSupporting Member

Apr 11, 2002
Los Angeles
I think in this situation, mixing a 5.3 ohm 310
cab at 103db sensitivity, and an 8 ohm 112 cab
at 100db sensitivity, may not work too well if
the information i'm getting is correct.

18. ### BassIan

Apr 27, 2003
Cupertino, California
Very true. I hadn't looked at the sensitivity ratings of those cabinets. IF it were the other way around, with the 8 ohm cab having the higher sensitivity, it wouldn't likely be a problem, but in this case it is likely that the 112 will be pretty quiet compared to the 310.

19. ### IvanMikePlayer Characters fear me...Supporting Member

Nov 10, 2002
Middletown CT, USA
all very good points...............
one thing to consider, just because a 210 has half the speakers and surface area than a 410 doesnt mean that it would be a good idea to run a 16 ohm 210 with an 8 ohm 410
i used an 8 ohm 210 and an 8 ohm 410 together on the same mono amp for years and it sounded fantastic - the 210 sounded equally as loud as the 410, this is a very common setup with eden gear

20. ### De Teng

Oct 27, 2003
Utrecht, Holland
Alright... but how come? May be it is because the 4.10 has a bigger housing, thus produces more sound.... so it is in the end equally loud?