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View Full Version : Parrallel vs. series



phebus
10-31-2004, 04:28 PM
Can someone tell me how the two relate to amp output. I know how to wire either way, but I'm not sure exactly how they effect amp output as far as the ohm ratings go.
For example, when is it better to wire a dual voice coil sub in either series or parralel? Or, when daisy chaining speakers together, when is it better to use one over the other? I have been told how to wire particular setups, but I would like to know the reasons.
Thanks

Havasu Hangin'
10-31-2004, 06:54 PM
When you change the way a speaker (or group of speakers) is wired (series vs parallel), then you change the ohm load that the amp "sees".
For example, a dual 4 ohm speaker can show an amp a 2 ohm load (parallel) or a 8 ohm load (series). Add another speaker and the same math applies.
Two 2 ohm subs in series is a 4 ohm load on the amp, and in parallel is a 1 ohm load.
Unless an amp has a regulated power supply, an ohm load on an amp is kinda like a throttle on an engine- the lower the ohm load, the more watts the amp is allowed to output. Ohms = resistance, so the more resistance, the less the amp will output. Usually, more output = more heat, so there is a tradeoff.
Hope I didn't confuse you too much.

Tom Brown
10-31-2004, 08:39 PM
...the lower the ohm load, the more watts the amp is allowed to output.
The output stages of most modern amplifiers contain loading circuitry that will put a lower limit on the load impedance. At some point, these amplifiers stop increasing their output as driver impedance is lowered because the actual impedance across the output stage of the amp is given a lower limit to protect the output circuitry.
If you were connected straight to the output transistors, power would double as impedance halved.
Hey... I know how contentious this subject is but at some point, lowering impedance will only make an amp run hotter. Actual magnetic flux across the gap of a voice coil will stop rising at some point and there's no benefit lowering the impedance beyond that point unless you want to win a numbers race. Even two ohm is a tough load for a high frequency switching power supply as is used in a car audio amp.

phebus
10-31-2004, 09:00 PM
I understand that if you have two 4 ohm speakers wired in parrallel, you end up with a 2 ohm load on the amp, but I don't understand how it works. If you have a 4 ohm speaker wired by itself, of course you have a 4 ohm load (like a resistor), but by adding another speaker (in parrallel) with another 4 ohm load I don't know how you lower resistance to 2 ohms. The current still has to pass through a 4 ohm resistance (voice coil), and in this case two (although not in series which I understand would increase to 8 ohms). Baffling!! :confused:

Havasu Hangin'
10-31-2004, 09:48 PM
I understand that if you have two 4 ohm speakers wired in parrallel, you end up with a 2 ohm load on the amp, but I don't understand how it works. If you have a 4 ohm speaker wired by itself, of course you have a 4 ohm load (like a resistor), but by adding another speaker (in parrallel) with another 4 ohm load I don't know how you lower resistance to 2 ohms. The current still has to pass through a 4 ohm resistance (voice coil), and in this case two (although not in series which I understand would increase to 8 ohms). Baffling!! :confused:
A speaker is nothing more than a resistor.
Here's (http://www.termpro.com/articles/spkrz.html) some formulas.
Stacking adds resistance (series), but spliiting it subtracts (parallel).

phebus
11-01-2004, 06:39 AM
Thanks for the link HH, it helped me understand it. But, now I have a three ways to think about parrallel, series, and parrallel/series combo.
Also, a sub with a dual voice coil off a mono amp is looked at like two speakers right?

Havasu Hangin'
11-01-2004, 06:57 AM
Thanks for the link HH, it helped me understand it. But, now I have a three ways to think about parrallel, series, and parrallel/series combo.
Also, a sub with a dual voice coil off a mono amp is looked at like two speakers right?
Yep...the VC is the resistor. If you have four dual VC subs, then it is really like eight subs to work with, and parallel/series will usually get you to your desired ohm load on the amp.
In the old days, we had to order special subs when running multiple subs off one amp...but now with dual VC subs...no worries.

ROZ
11-01-2004, 01:16 PM
In the old days, we had to order special subs when running multiple subs off one amp...but now with dual VC subs...no worries.
Yup, the good ole days... There was a time when the VC on a DVC driver was longer as well. Today the DVC benefit is wiring variation, just like HH said.
remember ordering 12ohm drivers? :D

CEO
11-01-2004, 04:01 PM
What happened to the days of R+, R- and F+, F- ?