If I bridge 2 4ohm subwoofers together, does it change it to 8ohms? 2ohms? Any change?

Question

Hello,

I have two simple 20watt subwoofers that are both 4ohms each. These are home audio subwoofers that I pulled from a Creative Audio setup.

I have a receiver that says it only works with 6ohm and 8ohm speakers.

Is there any way to connect these two together to make them work with the receiver without blowing them?

Answer 1

It does not work like resistance. The measurement refers to IMPEDANCE not resistance, and ohms law does not apply. sorry but most here are WRONG.

Answer 2

Connecting them in parallel will give you a 2 ohm load.

Connecting them in series will give you an 8 ohm load.

http://www.termpro.com/articles/spkrz.ht...

If you try hooking your sub up to the same output as another 8 ohm speaker, you'd be back to a 4 ohm load. It would need to be hooked up to it's own output, or a speaker selector switch designed to safely operate multiple speakers could be used.

I don't know how you'd hook this thing up to one channel or the other without causing a channel imbalance in the loudness of the main speakers though...  If you built two of these things and your receiver had A and B speaker outputs...  that would work.

The best design for a passive sub would be to use two  8 ohm sub drivers connected to the main stereo channels of the amp. The sub would contain a simple two-way crossover for each channel that passes everything under a certain frequency to the sub drivers and everything over a certain frequency to some speaker jacks where you'd plug in your regular speakers. This way, any given frequency would only drive the 8 ohm sub or the 8 ohm speaker, depending on the frequency. Alternatively, you could use a single sub driver with twin 8 ohm voice coils instead of dual drivers. That's the way most passive subs worked before powered subs became popular and how speakers with passive subs like some of the Bose models are still designed. The speaker cables run from the amp to the sub and the satelites are plugged into the sub that contains a crossover.

42 is obviously faking being an electrical engineer because my link clearly shows the formulas for figuring impedance in speaker hookups. Not only are the formulas quite correct, but also extremely elementary for any REAL electrical engineer.

Answer 3

YES YES YES.

Edit- But you can only use one channel ,either Left or Right but no way to use both channels. For subs it is not that important though. Most bass is the same for both channels.

Anyone that says you can't are wrong.

But remember the OHMS listing on your receiver is for IMPEDENCE not RESISTANCE

Connect them up in series.

Connect your + lead from your amp to the + on one speaker then connect the - of that speaker to the + on the other speaker. Then connect the - lead of the second speaker to the - on your amp.

Impedence OHMS is resistence to alternating current.

Speakers use alternating current.

Resistance OHMS is resistence to direct current.

Both are measured using OHMS but are different.

In all actuallity 8ohms impedence is about 6 ohms resistive.

But speakers do not use direct current. The only time a speaker will see direct current is when an amplifier clips. Direct current destroys speakers.

Now for all intensive purposes you can use the following. It is not rocket science.

If the impedence is the same for 2 speakers the impedence gets split in half if they are connected in parallel. The impedence doubles if they are connected in series.

If you start connecting more than 2 speakers together with varying impedences then it gets more tricky. But for your application you will be fine to connect them in series. That will give you 8 ohms impedence.

Parallel 8 and 8 = 4 ohm

4 and 4 = 2ohm

series 8 and 8 = 16 ohm

4 and 4 = 8 ohm

Answer 4

if you  wire them: positive on one speaker to the amp and the other negative to the amp then the remaining positive and negative to each other you will get an 8 ohm load aka series

Answer 5

The answer is No.  You HAVE to have a speaker Ohm load that matches the Ohm load of the receiver or else the speakers WILL blow out or cause very nasty distortion.  Think of it this way.  If you run an 8 Ohm load (power) from the receiver to ONLY one connected speaker by way of one set of terminals (channels; 1 negative & 1 positive) capable of withstanding 8 Ohms you are in perfect harmony.  

Add another speaker to the setup connecting each speaker to each set of terminals (channels) seperately & you are still in perfect harmony.  

On the other hand, if you take the same 8 Ohm load & connect 2-4 Ohm speakers together by way of 1 bridged terminal (both the negative & positive of each channel connected to make one channel total) the speakers will act as one with double the power.

The above setup would "see" only 1 speaker & double the power, making the speakers distort enough to pop or explode.

Only way for setup to "see" the 8 Ohm load is by series as stated above by previous contributors.

Answer 6

Bridging your subs will make them 2 ohms, you should get 8 ohm speakers if you use the amp your referring to.