ohms, watts, bridging, confused?????

[Unregistered]

i see and hear alot of information regarding ohms, watts, and amp bridging... but i am having a little trouble understanding it all. i know that if you wire two 4 ohm sub in parallel they create a 2 ohm load. but, what if you wire three 4 ohm subs in parallel, what is the ohm load being created and what is the formula?

someone told me that if you wire two 4ohm subs in parallel and drive them with a two channel amp bridged to mono, this creates a 1 ohm load, is this correct?

in the above scenario, if the amp is 100w x 2, and 200w bridged, it makes sense to me that each sub would receive 100w each - if using a mono amp does the total watts get divided evenly among all subs connected, weather its 2, 3, or 4?

please help me understand!!!

thanks

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[IASCA pro 301-6 10+ year member]

the reason that two four ohm subs, when connected to an amp with a load of two ohms creates a one ohm load is because when bridging an amp, it "sees" half of the load it is given. This is due to the topography of the design of the amp. There are amps on the market that both do this as well as a number of new amps that compensate for the ohm load and they do not see this half-load. You need to be aware of the specs on the amp you are looking at. If it is spec'd to handle a two ohm load, do not give it more than two ohms...its that easy.

As for the formula to calculate ohm load:

1 devided by the the sum of 1 devided by r1 plus 1 devided r2 plus 1 devided by rn. This sound real confusing in print, but it makes more sence if you see it. To answer your question: three 4 ohm subs in parellel is 1.33 ohms.

Todd

 

[lbzrider14 10+ year member]

What does Parallel mean when wiring a sub? also, in that formula, what does r1. r2, and rn represent?

 

[lloyd]

Originally posted by lbzrider14 What does Parallel mean when wiring a sub? also, in that fo

the easiest way to calculate the impedance of speakers in parallel is to take the resistance and divide by the number of speakers. Example three 4 ohm speakers would be 4 divide by three=1.333ohms. Parallel means the same for a sub as it does for any speaker. the positive and negative from the terminals are shared.positive from amp goes to positive of two speakers for example, and same for negative.Think of it as two swings tied to the same point at the top.