Re: Speaker Z's Continued

["Merlyn Plotz" <MERLYNP@TC-MANKATO.SCM.TEC.MN.US>]

> Date:          Wed, 06 Mar 1996 19:07:27 -0700
> To:            quattro@coimbra.ans.net
> From:          Brooks Ellis <brooks@fortnet.org>
> Subject:       Speaker impedences

> >> Actually, if you wanted to , you could build a pseudo-surround system 
> >> in your car by wiring four speakers like this:
> >> 
> >> From the positive terminal of the front outputs, you would wire like 
> >> this (flow of power is from left to right, from + to -).
> >> 
> >> +___ +(spkr 1)- ___ +(spkr 2)- ___ +(spkr 3)- ___ +spkr 4)- ___ -
> 
> I do not see why this would do anything other than give you a 'pseudo-mono'
> system. all of the speakers would do the exact same thing!
> 
> 
> >I thought I had this set up so it would not load up the amplifier's 
> >output and melt things - but Merlyn's post indicated I was wrong.  
> >The fact that I got away with this for a while in a home stereo (at 
> >low volumes) does not assure its safety.  So DON'T do it.
> 
> Well, if you wire them all to the same source, the impedence will be
> something like, 16 ohms. I wouldn't worry about blowing your amp with that
> MUCH restistance. If you wired them all in series, you might have to worry
> about haveing too LITTLE resistance - 1 ohm! That would be fine, for a good
> compitition amp, but not for say, a Bose system, or a Delta head unit/system.
> 
> If you were connecting them all to the head unit's amp, AND all of them
> together...why?
> 
> Brooks
> 
******
If speakers were totally resistive (they aren't - more in this 
later), then the total resistance when connecting in series
would be the sum of all individual speaker's resistances. 
Example; If each were 8 ohms, the total would be 32 ohms.

(+) --- + SPK#1 - --- + SPK#2 - --- + SPK#3 - --- + SPK#4 - ----- (-)

If the same were connected in parallel, the resistance would
be, 2 ohms.

(+) --|----- + SPK#1 - ---|
       |                          |
       |----- + SPK#2 - ---|
       |                          |
       |----- + SPK#3 - ---|
       |                          |
       |----- + SPK#4 - ---|
                                  |
(-) ------------------------------|

Speakers are fairly complex. They exhibit impedance,
which is a combination of mainly resistance and 
inductance. The idea is somwhat similar to the results 
obtained with resistances only.

A series / parallel combination of similar speakers can 
be used to maintain the same load impedance. Here goes,
I hope the straight text / graphic emulations are readable.

(+) --|----- + SPK#1 - ---|
       |                          |
       |----- + SPK#2 - ---|
                                  |
       |------ - SPK#3 +---|
       |                          |
(-) ---|------ - SPK#4 +---|

One must be careful of the fact that sometimes
speaker manufacturers may choose to ground
one of the terminals to the frame of the speaker.
This would create a real mess if the frame were to
be connected to the car's frame!!!

Merlyn

  
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