How do i connect my 4 ohm subwoofer to my 8 ohm reciever ?

Hello my good friends,

The heading explains it all, I have a Onkyo 8 ohm reciever, and a 4 ohm Bose 15" sub woofer. Ive searched high and low on Googs, always conflicting answers, called Jaycar and other reputable audio places..... and nothing.

It 2012, surely im not the first to raise this question, in this day and age, nothing should be impossible.

Help Help Help !!!

Your search may not have included the proper terminology. There's a wealth of information available if you do a Google search for "speaker impedance matching". Hope that helps.

High quality impedance matching transformers can be costly. You could wire two 4-ohm speakers in series.

reply to post by scubagravy

Just a thought but couldn't you just get a 4 ohm resistor and put it in series with the speaker?

I know when I tried to connect my Amp and Sub-Woofer to my computer.

I think I blew it....



Not sure if it works now.

reply to post by scubagravy


Firstly what is an 'Onkyo 8 ohm reciever' ?

Is that a radio or something ?

As for the speaker, you could connect a 4 ohm wire wound resistor in series with the speaker (one terminal of the speaker connects to the resistor and the speaker wires connect one speaker terminal and one side of the resister).

The resistor will look like this

This will work but most amplifiers will happily drive into a 4 ohm speaker.
The amplifiers will however get hotter as the amplifier is driving more power into the speaker.

hope it helps.

Originally posted by freedomguy
reply to post by scubagravy

 

Just a thought but couldn't you just get a 4 ohm resistor and put it in series with the speaker?

That is one option, but you need a high wattage resistor, especially since it is for a subwoofer and most of the power in the audio signal is in the lower frequency range.

It's effective but inefficient because half the power is dissipated in the resistor as heat. Depending on the current and the resistor used, it could get a little toasty.

reply to post by scubagravy


Thankyou all, still conflicting answers..... what ive come to think is that i shall put the 15" in a box and i shall cut out a spot for a panel amp. That way i can select a 4 ohm panel amp, run it from the wall at 240v and just carry the music signal via RCA from the 8 ohm reciever .... what do you guys think ??

reply to post by scubagravy


I think you just replied to yourself!


No, but unless it's a dual voice coil speaker you really shouldn't run a 4ohm speaker from an 8ohm receiver. The amplifier will overwork and eventually give out. I don't know how long that may take, but it will happen.

My advice is exactly what your last post said.
Run the sub from a separate power supply and just source the audio signal in.
If you could "bridge" the output of the receiver to 4ohms, then yes you could run it.
But that would mean your receiver would need two 8ohm subwoofer outputs.
Most receivers only have one output.

Most home audio receivers have powered subwoofers for this exact purpose.
The subs draw alot of power from the receiver so most companys build their power amp separate.

My advice? Either get an 8ohm sub or separately amplify the one you have.

Does your receiver have a dedicated subwoofer out?
If not you'll have to buy a crossover which separates the frequencies.

Yup, I think what cha need is going to be some kind of a crossover network.

www.mcmelectronics.com...&green=10E5D768-2A6B-5801-AF2B-4A00C0387B88&utm_campaign=MyBuys&utm_medium=Recommendation&utm_source=pr od&utm_term=555-15330

www.parts-express.com...

THe output impedance of your amp is 8 ohms. Your speaker impedance is 4 ohms. It is important to match the impedance of the output to the speaker with some kind of matching circuit. For maximum power transfer and even to prevent damage to the amp you must match the impedance with a matching circuit.

A simple resistor is not what you need. I think a crossover might work but you need to do some research to find the correct one.

This is pretty straight forward -

wiki.answers.com...

www.audioholics.com...

I googled -- 8 ohm output 4 ohm speaker - millions of hits.