Can/should I use 3 Ohm sub with 8 Ohm system?

[Super-D-38]

Hi, I have an RCA 650 W system that runs all speakers at 8 Ohms...

As a typical Guy I wish to get more bass..
A friend had an older RCA sub that runs 3 Ohms at 50 -200 W

The Sub channel on my system puts out 150 W so I know that is good..
I know also that I would need to use a 5 Ohm resistor to get this extra sub to 8 Ohms...

Now the questions:
1: Can I use this sub? (with the resistor that is.)
2: If I can what "side" do I put the resistor on... ( + or - )
3: Can I also keep using my existing sub and just plug this one in too? (same sub port)

Thanks in advance...

 

[WmAx]

Now the questions:
1: Can I use this sub? (with the resistor that is.)

Yes.

2: If I can what "side" do I put the resistor on... ( + or - )

Doesn't matter. But + is more logical.

3: Can I also keep using my existing sub and just plug this one in too? (same sub port)

I'm not sure what you mean. If you have two passive subs connected to the single amplifier output, then connect them in series. You will be able to avoid the resistor in this configuration.

If you use a resistor, you need to use a non-inductive load resistor, which is typically used for amplifier testing. I recommend a rating that matches the input RMS rating of your subwoofer, or the output power rating of your amplifier, which ever is smaller.

Be prepared for somewhat 'peaked' bass response. When you add this much resistance to the circuit, the speaker is going to develop frequency response peaks at the hi impedance peaks of the bass alignment tuning. Don't ask me how much, exactly, as this would require an impedance plot of your speaker for me to accurately simulate. However, I would not be suprised if you experienced 4-6dB peaks with the ratios to be expected in your case. But considering that peaks in the typical room exceed this, you might not even be bothered by this effect.

If you want to do this right, just wait until this is in stock for $125.00:

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=300-632

Seems to be a lot of good words from people, concerning this product's value.

-Chris

 

[Super-D-38]

Thanks for the reply..

As far as the $125 sub....... Uh I think not..
"Free and almost free is the way for me".

The last answer kinda started over my head..
I understood up to in series, after that my brain just went "Huh??"..

My receiver has a "powered" sub out.. and another sub "pre-out" I think..
Though that would then require an extra amp.

What I was thinking, was to just use the same sub out (+ -) to run the two subs..

Now I have an understanding of series, but how would I go about it with these two subs?
They are both in the factory sealed boxes, and I would prefer not to open them..

So could it go something like: from amp to original sub, then from orig sub over to extra sub ?

They have those spring loaded "clamping" things for the wires to go into...
They being the two subs and the receiver...

Also the "Extra" sub says its a "dual driver" will this effect my choice of configuration?

Please for give my ignorace, I'm still new to this stuff...
Could you "dumb" down your answers a bit.. Thanks.

 

[WmAx]

The last answer kinda started over my head..
I understood up to in series, after that my brain just went "Huh??"..

What I was thinking, was to just use the same sub out (+ -) to run the two subs..

Now I have an understanding of series, but how would I go about it with these two subs?

Since I am not there to *see* the actual conditions/equipment, I have to assume you have speaker terminals available, that are connected from the back of the cabinet, wired directly to each individual subwoofer driver. You did imply earlier that you had two passive subwoofers.

Then a standard series connection is in order:

-Chris

 

[Super-D-38]

Ah, yes just as I thought.. OK and this configuation will allow me to use the 3 Ohm sub without the resistor, correct?

I will give this a try today... Woo Hoo more bass!! That will rock!.... Or is that "Thump"??..

Thanks Loads,...

 

[Super-D-38]

Ok, I've tried it.. Good news, I didn't fry it... Bad news is the extra woofer isn't getting enough power.
Cant really hear it or feel it.. The original one still seems to work fine..
So I guess I'm gonna need an amp for the "Dual driver super woofer".

Oh well I learned a new thing, even if I can't use it right now..
Thanks for the help WmAx