# When 4 ohms + 4 ohms= 8 ohms

Discussion in 'Amps and Cabs [BG]' started by FunkySpoo, May 30, 2002.

Feb 6, 2002
2. ### AllodoX

we knew that

parallel = less resistance coz : 1/total = (1/cab1) + (1/cab2)
serial = more resistance coz : total = cab1 + cab2

Feb 6, 2002
oh

4. ### Johnny BoomBoom

Jun 8, 2001
Glasgow, Scotland
Yes this is correct. If you link cabs, resistors, loads whatever you want to call them, then the formula for resistance you use is:-

Rt = R1+R2+R3+R4 +.........+Rn

Where Rt is the total resistance

If you link them in parallel, the formula you use is:-

1/Rt = 1/R1+1/R2+1/R3+.......+1/Rn

One is conservation of energy, one is conservation of charge. I could prove this from first principles many years ago, but trust me on this one!

5. ### Nino ValentiSupporting MemberCommercial User

Feb 2, 2001
Staten Island NYC
Builder: Valenti Basses
I truly doubt that everyone knew that.

6. ### ZuluFunkNot Impressed By Those Who Flaunt “Authority”Supporting Member

Apr 14, 2001
Pennsylvania
I never knew of anyone hooking up in series though. Is daisy-chaining considered paralel?

Usually, I run stereo.
If I hook my top 210 into the mono out with a banana clip cable into the 1/4" into the speaker, then another banana clip out to the 115's 1/4" in, is this a parallel?

7. ### Richard Lindsey

Mar 25, 2000
SF Bay Area
Daisy-chaining is almost always parallel IME, the reason being that the second jack on cab 1 is connected directly to the first jack. So the signal going into the input of cab 1 doesn't go through cab 1's speakers and then into cab 2 (which would be series): it "splits off" at the input of cab 1 and goes to cab 1's speakers and cab 2's more or less simultaneously (parallel).

8. ### Johnny BoomBoom

Jun 8, 2001
Glasgow, Scotland

I am unaware of anyone that does. I don't think it would work well in the bass environment! That's why everybody usues parallel wiring!

9. ### Richard Lindsey

Mar 25, 2000
SF Bay Area
Actually, *within* cabinets, at least in the form of series-parallel wiring, it's quite common. That's how you put together four 8 ohm 10s and get an 8 ohm cab--good old series-parallel.

But you're right, I don't know of anybody who links discrete *cabs* in series, and most dual speaker outputs on amps are in parallel.

10. ### FunkySpooSupporting Member

Feb 6, 2002
I think Eden has this in there speaker manual because you can't run their heads at 4 ohms bridged. So if you have an Eden head and want the option of running bi-amp or bridge, you buy two 4 ohm cabs for bi-amp mode or hook them up in series for bridge mode. Does that sound logical or am I missing something?

11. ### Johnny BoomBoom

Jun 8, 2001
Glasgow, Scotland

Yes two arms of speakers linked in series - then wired as parallel. Bingo - a parallel circuit! The system isn't clever enough to know that the load in each arm is actually made up of two in series! Therefore, the cab is effectively wired in parallel.

Ever thought they might use 16 ohm speakers - totally in parallel????

12. ### Oysterman

Mar 30, 2000
Sweden
Aren't you taught things like this in school? I was.

Though I have to admit I always tend to mix up series and parallell...

13. ### Richard Lindsey

Mar 25, 2000
SF Bay Area
Well, of course--but that would give you a 4 ohm cab. Not unusual, naturally, but my comment specifically had to do with 8 ohm cabs, and more specifically, how you get an 8 ohm cab with four 8 ohm drivers, which is quite common.

14. ### Johnny BoomBoom

Jun 8, 2001
Glasgow, Scotland

OK, fair point!

15. ### jamminji

Mar 22, 2002
Really it all comes down to what your specs are. You wire your cabs to meet your specs. Even though parallel IS more common on a brand name dual jack cabs, if series gets you the ohms you want then you set it up in series. Large quanity cab systems (PA's) can get quite complicated. Ever see the DEAD's "WALL OF SOUND"? Now there was an OHM matching NIGHTMARE...lol

jam

16. ### Gallient Knight

Jul 31, 2001
Milford CT
I have meesed with this sort of thing in a pa system. it lets you run almost an infinite number of speaker cabinets under one amp. If might help if you goal is 10 4 by 10's on one amp

17. ### PrimaryTB Assistant

Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

Dec 3, 2020