4 ohm/8 ohm cunundrum?

Question

Kenwood av amp has a 8 ohm subwoofer output and a 8 ohm matched passive speaker.Bass is crap cos am spoilt by a Paradigm Active used in another room.
What would be the consequences of using a 4ohm active subby in the 8ohm passive output? Any suggestions for thunderous bass greatly appreciated, friends. Paul.

Answer 1

The concequences my friend is that you amp would be running through a speaker with 1/2 the resistance it should have and basically it could cause your amp to overheat and blow up unless it has an overloud trip built in it, what I would suggest if you must use your 4ohm subby as you call it is to change it impedence how so you ask? I will tell you if you put a 4ohm resistor in series with you speaker it will make it an 8 ohm speaker not a 4ohm one clever eh! I hope this helps

Answer 2

If you have an active subwoofer, the input is not driving the speaker directly, but is really feeding an amplifier. Therefore, all discussion of speaker impedance matching is irrelevant. What really matters in this case is signal level. Amplifier input impedances are very high and can be driven from low impedance source like the 8 ohm speaker output. Most amplifiers are designed for "line level" (about 1V rms) signal levels. A 10W signal into an 8-ohm load is about 8v. This may overload the amp. Some active woofers are designed to operate from speaker outputs, or will recommend a way to connect a speaker output to the amp input.

Answer 3

I take it the Kenwood has no line level sub out to use (if it does just use this). If you send the bass signal through a speaker level connection to the active sub, the the active sub cuts the signal down to line level and then uses its own amp. At that point there is no impedance problem since the signal the sub uses is then line level and you are using the sub's own amp. No conundrum. You don't say anything about the other speakers. If your Paradigm sub has speaker level inputs it will also have speaker level outputs to the mains. In the unlikely event it does not have speaker level outs you can hook it up to the speaker 2 outputs on the receiver and keep the main L&R speakers hooked up to speaker 1. If you do this just be sure to set your mains to small in the receiver's menu if they are too small to handle low bass.

Answer 4

Is the Sub active or Passive? You may want to consider replacing the passive sub with a active one. Or replace the amp that doesn't have a sub pre out(LFE) for one that does.

Secondly, to the other posters, it is not resistance it is IMPEDANCE. They are not interchangeable term, get with it!!!!

Your goal is to impedance match, yes? The cheap way would be to get a speakers selector that has variable output impedance. Or get different equipment.

Answer 5

The miss-match in the impedance will obviously result in loss of power, in your case thunder. You will need to insert an amplifier with 8 ohm input and 8 ohm output to boost the bass to match the 8 ohm speaker. Or a 4 ohm output for the 4 ohm speaker. You will probably have to find someone to design and build it for you.

Answer 6

eh