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December-24th-2001, 07:16 PM

#16

douggie

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Join Date: Oct 2001

Posts: 484

Hehe, yeah, hihoslva posted the math stuff for me

Anyway, it depends how you connect the tweeters together. If you connect them in parallel, the resistance will decrease. On the other hand, if you connect them in series, the resistance will increase. With a lower resistance, your amp has to work harder because of the increase current flow thru the speakers.

December-25th-2001, 10:17 AM

#17

JJB

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Join Date: Oct 2001

Posts: 731

Quote:

Originally posted by hihoslva
Also, I am running the tweeters "in-line" with the front speakers - basically they are spliced into the front speaker wires. Wouldn't this INCREASE the ohm load on the deck, rather than decrease it? How could adding MORE speakers decrease the resisitance across the circuit? Doesn't it add more resisitance?

Merry Christmas

I think that what you are describing is basically a parallel comination which means that the impedance actually drops. What happens in that situation is that the voltage through each of the parallel legs of the circuit is the same, and thus the current that is flowing down each of the branches is less.

In the case of two equal impedances it would the half as much (a pair of 8ohm speakers in parallel would yield a 4ohm impedance).

the basic formula for more than one is

Code:

POS----+----+----+---
       |    |    |
      (1)  (2)  (3)
       |    |    |
NEG----+----+----+---

Z = impedance

Ztotal = ( (1/Zone) + (1/Ztwo) + (1/Zthree) +.... )^(-1)

if instead you put your speakers in series (not that I have ever heard of this being done, but I can be sure someone has done it) then the impedances add up. The current through each speaker is the same, but the voltage drops a little as it passes through each speaker.

Code:

POS---(1)---(2)---(3)---+
                        |
NEG---------------------+

Ztotal = Zone + Ztwo + Zthree +...

hope that helps.

December-28th-2001, 12:57 PM

#18

mazdaspeedwest

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Location: Huntington Beach, CA Uhhh Surfs up Dude

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yup, thats pretty much it, but to put it in lamens terms

pos > pos > pos > .......neg > neg > neg>..... this is Paralell
this lowers the impedence
(i.e. two 4ohm speakers will drop to a single 2ohm load)

pos>neg>pos>neg.....this is Series
this raises the impedenc
(i.e. two 4ohm speakers will raise up to an 8ohm load)

the lower the impedence, the more efficient the speaker becomes, but the harder the amp has to work, creating more heat and more current draw. But it also raises the power output.

the higher the impedence, the less efficient the speakers are, but the amp is happy just cruising along. Less power is output, but the amp will stay cooler and have less current draw.

IMHO, stay within 2 to 4ohms for satelitte speakers and between 1 and 4ohms for subwoofers. no matter how you wire them all up.

December-28th-2001, 02:22 PM

#19

bluephone

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Join Date: Dec 2001

Location: Vancouver, BC

Posts: 1

Hi... first time on here, and am I ever glad I found this board! I'm just about to put in a 250W MTX 10" sub and 250W Pioneer amp to drive it... got a custom-built box with the sub facing the rear of the hatch, port facing upwards, and the amp flush-mounted beside the sub... only 8" thick, so I still get to use most of the hatch.

Here's my question - I've still got the factory head unit, so I was thinking of splicing into the wiring for the rear speakers and using that as an input for the amp - will that work? I don't know enough about car audio

Any ideas? Thanks...

BTW, I'm not looking for thumping bass - I listen to a lot of jazz, so I just want to be able to hear the low end without taxing the back speakers too much.