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Speakers Wired in Series Versus in Parallel


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numi 
Member - Posts: 11
Member spacespace
Joined: February 08, 2015
Location: California, United States
Posted: February 09, 2015 at 12:45 AM / IP Logged  
Wait, so actually, I guess that would be only one speaker from each channel, and if I'd connect another speaker off of either speaker in parallel, there would be a potential problem... then I might blow the stereo head unit.
So I'd want to wire any extra speakers from any of my 4 original speakers from this 4 speaker stereo in series, but I'd lose a little volume, right?
Thanks,
numi
numi
oldspark 
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Joined: November 03, 2008
Location: Australia
Posted: February 09, 2015 at 12:50 AM / IP Logged  
Yes, you'd lose half the power (usually; approximately).
But go back to basics, WHY do you want to add extra speakers?
numi 
Member - Posts: 11
Member spacespace
Joined: February 08, 2015
Location: California, United States
Posted: February 09, 2015 at 1:05 AM / IP Logged  
But wait, now I'm a little confused... if the stereo says "Speaker impedance 4-8 Ohms", that means simply having two 4 Ohm speakers would be the limit, and if I had any more draw on the stereo with any more speakers, like the back speakers, then that in itself, without any speakers run in parallel or in series, then it might cause a problem for this stereo head unit?
So, am I screwed with just 4 speakers.
Okay, I had a stock car stereo that crapped out, and it had six speakers... two in the dash, two in the doors, and two in the back.
Now I've hooked up a new stereo unit, but it only plays to the dash speakers and the back speakers, but I haven't turned it up very loud in my tests.
But I'd like to get the door speakers working, and I was going to sacrifice the little dash speakers by running the wires from the dash speakers to the new door speakers that I've now managed to install in the doors in spite of some other installation problems.
So even with that configuration, with just 4 speakers, based on what you are saying, I'm going to have a problem... if I turn up the volume with just my door speakers at 4 Ohms each and my back speakers, Ohms unknown, am I going to blow my new stereo?
And then what I was potentially planning to do was to keep the dash speakers hooked up, maybe get some new ones, and then run the door speakers in series or in parallel from the dash speakers.
Please tell me this isn't right!
numi
numi
oldspark 
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Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 09, 2015 at 1:23 AM / IP Logged  
I've said what I've said. Maybe you can reread it?   
You can wire 2 4 Ohm speakers in series for each output...
And that will reduce the maximum power output of your stereo.
And it may make the sound worse since you can't just add speakers willy-nilly. Only occasional luck else design result in good or improved sound.   
If it's a typical/traditional amp, forget the "4 to 8 Ohms" spec. It effectively means "a minimum of 4 Ohms".
Less than 4 Ohms will blow the output (eg, at high volumes or peaks).
And the higher the Ohmage, the lower the power output will be (ie, max output, or undistorted output, or output at a certain volume control setting).
numi 
Member - Posts: 11
Member spacespace
Joined: February 08, 2015
Location: California, United States
Posted: February 09, 2015 at 4:33 AM / IP Logged  
Okay, so I'd only be wiring 2 speakers from the right front channel in series, and 2 speakers from the left channel in series, and then the single pair of back speakers would be the only ones on the rear left and right channel, and then I'd be okay, I guess.
That's great. Sorry for the re-asking, but all the data was mixing me up... in this case, I suppose I needed it put as simply as possible.
Thanks, OS.
numi
numi
oldspark 
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Posted: February 09, 2015 at 4:38 AM / IP Logged  
Yes, you won't have as much output power and you might have worse sound, but it's safe.
numi 
Member - Posts: 11
Member spacespace
Joined: February 08, 2015
Location: California, United States
Posted: February 09, 2015 at 1:12 PM / IP Logged  
Hi OS,
Here's what someone posted on this topic on another forum...
"the formula to calculate the impedance of 2 speakers in parallel is:
1 / ((1/R1) + (1/R2))
So in your case where you have a 4 ohm speaker in the dash and a 4 ohm speaker in the door, the formula becomes
1 / ((1/4 + 1/4))
Which becomes
1 / (2/4)
Which becomes
1 / (1/2)
Which becomes
2
So, if you wire those 2 speakers in parallel, the head unit will see a 2 ohm load across it’s terminals which is outside of it’s 4 - 8 ohm specification.
This means that if the head unit tries to feed power into that configuration it will trigger a protection circuit or burn out. "
This sort of made better sense of it for me.
numi
numi
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 09, 2015 at 2:36 PM / IP Logged  
Yes, my first reply...
oldspark wrote:
You can search for series & parallel (resistor) formulae & explanations.
2 speakers in series doubles overall resistance (hence generally 1/4 the power (output) but amplifiers may be different - eg, 1/2 the power output).
2 speakers in parallel halves overall resistance.
If an amp is rated for 4 Ohm or higher (or 1 Ohm & higher) you don't want 2 Ohm (or 0.5 Ohm)... you'll blow the amp at high power outputs.
I assumed you'd look up series & parallel if you wanted the tech stuff and hence find Wiki or similar.
But for equal resistances, the formula reduce to 2R & R/2 for series & parallel respectively (or nR & R/n where n is the number of resistors involved).
You then use P = k/R meaning Power delivered or used is inversely proportional to Resistance to understand the effect of a series or parallel connection (in your case).
[FYI: k is V*V or 1/(I*I) where V is the voltage across the resistance and I is the current thru it. That's from combining Ohm's Law V=IR and P=VI.]
numi 
Member - Posts: 11
Member spacespace
Joined: February 08, 2015
Location: California, United States
Posted: February 09, 2015 at 8:01 PM / IP Logged  
OS,
This car stereo project was really meant, in a way, to be a pleasant diversion from the rest of what's going on in life, and just getting the wiring conversion with a conversion harness to work for the head unit became an insanely stupid task, but then getting that done brought me to this speaker conundrum, where my door speakers were left out of the equation.
Then the problem became getting the wires from the dash speakers to instead drive the door speakers, and the only alternative is apparently creating a bypass wire/wires that will have to run from each dash speaker grill outside the dash in to a newly drilled hole in the front area of each door, which leaves wires open to get caught on me or any passenger in the front seat, as seen in my fictitious bypass wires mock-up image seen below, because getting to the either side of the rubber tube grommet that holds all the power window and power lock wires in between the doors and the door frames to run the dash speaker wires through to the door speakers, which in theory would be from inside the dash above the kick panels, and inside the front edge of the door, are impossible to see, and unreachable from the door speaker hole for anyone with a forearm shorter than about 3 feet.
Then there was the bad automotive design that would have required me to take off the door panels (and break the brittle snap-in pieces holding it on while potentially making the door panels unable to ever be right again) in order just to get to each door speaker, which I was, as of yesterday, able to avoid by cutting the plastic door panel with a sawzall around each door speaker because the stock holes for the door speakers weren't big enough to actually get to the speaker screws or to remove the the speaker itself... now that's solved, as also seen in the images below.
Then the other day I was reading an old thread on the subject of the door speakers and someone mentioned running speakers in series, and I started thinking how I might actually be able run all six of my speakers, and replace the dash speakers and the rear speakers, in addition to the new door speakers I'd already purchased, and maybe I'd really have something to listen to in this old Mazda minivan.
That's what opened up this can of worms about "in series versus in parallel".
So instead of a pleasant diversion, as originally intended, this entire project, and all this talk about Ohms and math formulas has made me feel more like chanting "Oooohhhhmmmm".
Thanks again,
numi
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
Speakers Wired in Series Versus in Parallel - Page 2 -- posted image.
numi
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: February 10, 2015 at 2:55 AM / IP Logged  
I don't suppose it was some car audio forum? I've made various comments on here about what I think of them tho there are some brilliant contributors.
Luckily we've had a few posts from audio forum guys which has only added support to my views.
No doubt the thread you read mentioned the (approximate) halving of the output power wrt to max output and volume control setting else explained the need to replace with speakers of half the existing speaker ohmage.
They should also have mentioned the complications of adding speakers - usual crossovers are used else proper design wrt location etc (phase delays to ears etc).   
Replacing existing speakers is common practice, but not adding speakers to existing wiring & speakers. (After all, the best sound is usually from single speakers per channel tho that may mean tweeters & midrange, and a separate sub etc.)
PS - my original question WHY do you want to add extra speakers? was intended from a project or DIY POV but a sound POV - ie, better sound? louder sound? etc. I thought the answer would can the project since all outcomes result in a negative outcome (tho audio power versus acoustic power at the ear has merits).
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