4 ohms 2 ohms?

[123R-Prozak]

Evening,

Im taking out my amp and sub and putting it into my new little car, before i didnt worry about rms and ohms, but now looking at the parts, ive got

225rms 4ohms sub

300rms 2ohms amp monoblock

is this good for my sub? what does it mean if the ohms is different? how much total power will be going to the sub if the ohms is 2 not 4??

thankyou for your help.

-Daniel

[DJKOR]

What amp have you got? Sometimes a model number will help. Otherwise to basically answer your question:

Your amp would say 300W RMS when given a 2 ohm load. You will be able to run a 4 ohm subwoofer off it without a problem. It usually only becomes an issue when you present less of a load than what it's rated for (ie. a 2 ohm stable amplifier running a 1 ohm sub) and not the other way around. Just bear in mind though that if it can deliver 300W RMS for a 2 ohm sub, then it will deliver less power for a 4 ohm sub. That figure depends on the amp that you have. At a rough guestimate, I would say you would have a maximum of 200W RMS when your amp is connected to a 4 ohm sub.

[123R-Prozak]

ahh

JBL CS300.1 - http://www.jbl.com/car/products/product_de...;CheckProduct=Y

MTX Thunder4512

so if its under 225 whats for the sub, is it under powered then? thats not too bad is it?? ive powered x2 of these subs of this amp for nearly 2 yrs, ran good..

Edited April 22, 2009 by 123R-Prozak

[DJKOR]

Not far off.... according to their specifications, you will get 200W RMS into a 4 ohm load.

CS300.1

• 200W RMS x 1 channel at 4 ohms and ²1% THD + N

• Signal-to-noise ratio: 100dBA (reference 1W into 4 ohms)

• 300W RMS x 1 channel at 2 ohms, 14.4V supply and ²1% THD + N

• Dynamic power: 460W at 2 ohms

• Effective damping factor: 6.395 at 4 ohms

• Frequency response: 10Hz – 300Hz (–3dB)

• Maximum input signal: 6V

• Maximum sensitivity: 100mV

• Output regulation: – 0.07dB at 4 ohms

• Dimensions (L x W x H): 12-11/16" x 10-1/4" x 2-3/16"

• Fuses: 20A x 2

so if its under 225 whats for the sub, is it under powered then? thats not too bad is it?? ive powered x2 of these subs of this amp for nearly 2 yrs, ran good..

Yeah, it will be underpowered. It won't kill your woofers or anything as long as it's not clipping.

[123R-Prozak]

Thanx DJ, i can live with that!

[Guest]

Not far off.... according to their specifications, you will get 200W RMS into a 4 ohm load.

CS300.1

• 200W RMS x 1 channel at 4 ohms and ²1% THD + N

• Signal-to-noise ratio: 100dBA (reference 1W into 4 ohms)

• 300W RMS x 1 channel at 2 ohms, 14.4V supply and ²1% THD + N

• Dynamic power: 460W at 2 ohms

• Effective damping factor: 6.395 at 4 ohms

• Frequency response: 10Hz – 300Hz (–3dB)

• Maximum input signal: 6V

• Maximum sensitivity: 100mV

• Output regulation: – 0.07dB at 4 ohms

• Dimensions (L x W x H): 12-11/16" x 10-1/4" x 2-3/16"

• Fuses: 20A x 2

so if its under 225 whats for the sub, is it under powered then? thats not too bad is it?? ive powered x2 of these subs of this amp for nearly 2 yrs, ran good..

Yeah, it will be underpowered. It won't kill your woofers or anything as long as it's not clipping.

Under/Over powered amps dont kill subs, clipping does!

[DJKOR]

Under/Over powered amps dont kill subs, clipping does!

That is very true. Just a fact to others, you can overpower a speaker (to a certain limit) provided you can keep the voice coil cool. Kind of the same concept of over-clocking a PC that is kept really cool.

BTW: Thanks for quoting me Mick. That's some great advice there, LOL.

[Eargunk]

agree, i am currently running 300 rms to my fronts which is rated at 90, i just turn down the gain extremely low and made sure it didnt clip through using a voltmeter and what not. time consuming but its worth it IMO

[Guest]

For those who don't know what clipping is/how it breaks speakers, here is some basic info.

Clipping occurs when you try to force an amplifier to provide more power than it can to a speaker (by setting the gain too high, having an underpowered amp, etc).

Normal audio signal is AC, which when viewed on an osciliscope will look like a wave, now when a signal is clipping, the 'peaks and valleys' of the wave are cut off, and become flat, because the amplifier is already outputting the as much power as it can before the top of the wave is reached.

When a speaker is receiving AC, it is moving, and while the voice coil is generating heat (due to current being passed through it) the movement of the speaker is keeping it cool, and thus it does get destroyed.

When an amp clips, the flat sections of the peaks and valleys are where the amp is passing DC to the speaker....

Now, DC when viewed on an osciliscope is a flat line, speakers do not like DC. Passing DC through a speaker will cause its voice coil to heat up, but not move and destroy it.

Some higher end amps have clipping detection, which is awesome and makes it very easy to tune your amplifier.

[123R-Prozak]

ahh thankyou for the advise on clipping...

ive upgraded the amp to 250rms, so sub is 225, gain isn't too high, maybee half.. so hope im safe, even tho the gain is at half it still pumps harder than the jbl 200rms..