Understanding Speaker Impedance and Speaker Switches

you before we look at what speak impedance means when connecting speakers we need to note that a stereo - amplifier has to individual amplifies built in one for the left channel and one for the right channel the same principles apply to both amps so to simplify our discussions we will talk about only one amp most stereo amps are designed for speakers with an impedance between 4 and 16 ohms the symbol for ohms is the Omega symbol so you connect the speaker to this amp on the back of this speaker or speaker box it says the impedance is 8 ohms 180 ohms speaker gives a total load impedance of 8 ohms this is what the amp is built for so it's happy if the speaker was rated at 6 times that's also fine as is a single speaker rated at 4 ohms now the fun starts what if you were to connect 2 speakers to the 1 amp if both speakers are 8 ohms and you have wired them in parallel you need to calculate the total load impedance an easy way is to use my speakers in parallel calculator this tells us the total load impedance is 4 ohms the app is built for this so that's fine now what happens if both speakers are 4 ohms the calculator tells us the total load impedance is now only 2 ohms way below the minimum for the amp one way to solve this situation is to Y the speakers in series we don't need a calculator for this as you only need to add the 2 speaker impedances together so 4 plus 4 gives the total load impedance of 8 ohms the amp is booked for this so that's now fine okay so what if you want 4 speakers connected to the 1 app let's say you have four eight ohm speakers wide in parallel the calculator tells us the total load impedance is only two ohms that's not good for the amp if you were to have four four ohm speakers wide in parallel then the total load impedance is even less and there's even more disastrous for the poor amp a solution is to use a combination of series and parallel connections which technically will work but is rarely practical often a better solution is to use a speaker's selector switch with impedance protection these are connected adjacent to the app and all the speakers are then connected to the switch speaker selector switches use one of three methods to provide impedance protection or impedance matching one method is to combine the speakers in a series parallel combination internally this shows you having to figure out the wiring this method also gives full power to a pair of speakers if I mean one pair is selected this method works best for two or four pairs of speakers only it is not used for six or more pairs of speakers speaker selectors which use series parallel switching tend to look like this they have no protection switch the second method of impedance protection is to use a series resistor a resistor normally around 4 ohms is put in series with the parallel speakers remember the total impedance of 4 ohm speakers in parallel it was 1 ohm for ohms in series with 1 ohm gives a total load impedance of 5 ohms which makes the app happy if you have 4 8 ohm speakers in parallel the speaker impedance is 2 ohms 4 ohms in series with 2 ohms gives a total load impedance of 6 ohms which is also good for the app speaker selectors which use series resistors tend to look like this inside there are two high-power resistors and not much else they normally have air vents for when the resistors get hot they also have a protection switch or something similar the switch is used when you have only one pair of speakers switched on this bypasses the resistor and connects a speaker directly to the end the third method of impedance protection uses transformers a transformer basically multiplies the speaker impedance if the multiplier is set to times four then the impedance of each speaker is multiplied by four so if for 8 ohms speakers each speaker would appear to have an impedance of 32 ohms the calculator tells us for lots of 32 ohms in parallel equals 8 ohms all good with 8 ohm speakers you could set the multiply 2 times 2 this would make each of the 8 ohm speakers look like 16 ohms the calculator tells us for 16 ohms in parallel equals 4 ohms no problems however if you have 4 ohm speakers and select times 2 then each speaker looks like 8 ohms and the calculator tells us for 8 ohms in parallel gives a total impedance of only 2 ohms not good however if the multiplier is switched 2 times 4 then each speaker looks like 16 ohms the calculator tells us for 16 ohms in parallel give a total impedance of 4 ohms this is fine for the app speaker selectors which use transformers for impedance matching look like this they mostly incorporate individual volume control for each zone they normally don't need ventilation and don't have a protection switch inside there are individual transforms for the left and right channel of each Zone on the rear of some there is a multiply switch which you set during installation in summary no matter how many speakers you have connected to one amp whether they are wired in series or parallel whether you use any type of speaker selector switch the total load impedance must be above the minimum impedance the app is designed for remember we have looked at 1 amp only in practice the methods mentioned need to be duplicated for each app for more information read the articles on connecting speakers on the website

Channel: Geoff the Grey Geek

Views: 2,692,852

Keywords: speaker impedance, speakers, speaker selector switch, multiple speakers, 4 ohms, 8 ohms, 6 ohms

Id: gvaojICThzg

Length: 7min 10sec (430 seconds)

Published: Tue Apr 26 2016