8 ohm - 4 ohm

[Danhoyland]

Hi guys. I wonder if you can help me. I have a pair of subs which are rated 650w RMS @ 8 ohms. I have an amp which is 450w @ 8ohm and 650w @ 4 ohm. Is there some way I can lower the resistance of the subs to get them to be a 4 ohm load? Is it just a case of wiring an 8 ohm resister in parallel with each sub? Help will be really appreciated.

 

[themadhippy]

yea just chuck in an 8 ohm resistor,make sure its rated for 450W as its going to get rather warm .Best give the amp an easy life and keep with 8 ohms,how much sub do you need any way?

 

[felix]

That'll gain you nothing - you'll be dropping about 320watts into the sub and 320watts as heat in the resistor - a complete waste.

Just drive the sub as an 8-ohm load. The amp will do a better job, and apply the full 450w rating to the sub.

 

[granville]

Purchase another two subs, and connect each pair in parallel.
sorted.

 

[robM]

themadhippy

yea just chuck in an 8 ohm resistor,make sure its rated for 450W as its going to get rather warm .Best give the amp an easy life and keep with 8 ohms,how much sub do you need any way?

Where on earth did you get this information from

 

[themadhippy]

Where on earth did you get this information from

if you meen

yea just chuck in an 8 ohm resistor,make sure its rated for 450W as its going to get rather warm

ohms law innit,2 8 ohm resitors in parralel gives 4 ohm,half the power to the driver,half the power to the resistor,cant be bothered with the maths but its going to get warm

or do you meen

Best give the amp an easy life and keep with 8 ohm

more ohms law im affraid
or

,how much sub do you need any way

If 2-3kw and a pair of twin 18" can produce bowel-loosening bass in a large venue then realisticly how much sub do you need in a domestic enviroment?

 

[sq225917]

This is the best advice thread I've ever read...

Add an 8ohm resistor- class.!

 

[robM]

This is the best advice thread I've ever read...

Add an 8ohm resistor- class.!

I think there should be a list of who can and who shouldn't give advise.

themadhippy - the 8,6 or 4 ohm figure on the back of a loudspeaker is the mean impedance figure and not a pure resistance figure.
Chucking a resistor somewhere on the rear terminal will do nothing but screw up the sound!
Even so, please dismiss that last statement as that might temp you into designing a pair of loudspeakers

 

[Dev]

That'll gain you nothing - you'll be dropping about 320watts into the sub and 320watts as heat in the resistor - a complete waste.

Just drive the sub as an 8-ohm load. The amp will do a better job, and apply the full 450w rating to the sub.

I'd personally take this advice.

 

[themadhippy]

might temp you into designing a pair of loudspeakers

I have been toying with getting a pair of beymar 15" coaxials,but the 3 way 4 foot "coffins" i build several years back still sound pretty good,their even better when run semi active via the home brewed crossover and the valve amps,but i just aint got the space any more to set it all up, also a sever case of the travel bug keeps eating funds set aside for other things.

 

[robM]

I built a pair of 15" cabs years ago...it was great fun doing it and they sounded awful in 'hifi' terms but did the job...