Ohms question

[ssmith]

If I have a speaker with an impedence of 4 ohms and an amp that is running in 2 ohms...am I actually getting the specs wattage delivered to the speaker?

ie. 4ohm speaker rated at 150w RMS powered by amp that is 150w @ 2ohms.

Seems as though if the speaker resistance(4 ohms) is higher than the amps 2 ohms, then full power (150w) wouldn't be delivered. So is a 4ohm speaker Ok to power with a amp in the 2ohm mode?

I know I'm just confused on all this stuff and I'm probably trying to over think it but I'd appreciate some clarification.

Thanks,
Scottie

[metalic]

What sub and amp you running? If it's a cheap amp they advertise Peak power 2 2ohms making it sound better than it really is. A model # would help so we would know specs but every amp I have dealt with is rated at 4ohms and stable down to 2 or 1ohm loads. I hope my example clears it up for you but if not I can go in more depth or someone else will chime in.
Example
I have a JL 8W3 @ 4ohm my amp is rated at 175@ 4ohm and 250@ 2ohm
I'm pushing 175 watts to that sub but if I was to wire a second 4ohm sub it would put a 2ohm load on the amp drawing 250 watts

[wetsounds1]

http://www.bcae1.com/

For those that are very interested in learning some basics. This site is a good resource.

In a quick breakdown

The speakers impedance is what will determine the load the amp "sees". You cannot make an amp play at a particular impedance. An amp will provide the power based on the load it sees. And how the speakers are wired.

Do you have TWO 4 ohm speakers wired in parallel to the amp on the same ch? If so this is the only way that amp would be seeing 2 ohms. Or do you only have one speaker per channel on the amp. If so, then the amp is only seeing a 4 ohm load and is producing around half of the 2 ohm rating.

If it is only one 4 ohm speaker per channel then the amp would most likely be doing 75 watts rms.

If in fact you have 2 speakers in parallel (postives together and negatives together) on that amp ch so it is in 2 ohm load for 150 at 2 ohms, you still only net 75 watts per speaker.

You have doubled the amount of speakers to create the lower load on the amp making it produce more power. But that power is then split between so your end net is the same.

The only way to look at the specs if what the amp will be producing at the load you will be running it in. If you have one pair of 4 ohm speakers to run in stereo on a 2 ch amp. The only rating you will need to know is the 4 ohm stereo rating.

Tim
Wet Sounds

[AirTool]

The maximum power delivered by an amplifier or power supply occurs when the resistance of the load (or combined load) matches the resistance of the amp.

When the load is less, less power will be delivered. When the load is more, less power will be delivered.

One trick with these amps is that the internal resistance varies with load and heat. So, figure that out.

The other rub is that music is delivered in an alternating current (AC) situation despite the (+) and (-) on the speakers. Both the load and the amp are not purely resistive....which further complicates the answer.

So back to the short answer....match the load to the amp.

[maxxwell]

Very few amplifiers now a days rate in 2 Ohm, would help to know the brand of the amp to get a clearer picture. The above posts are right in the money as far as what the amp sees when the speakers are in parallel or series and that varying resistance on AC current further changes the final output.

One other note is the quality of the amplifier as to what wattage is claimed. Some lower quality amps state output wattage as a whole, ie including clipping and distortion. I assume this would be a selling tactic, but who knows. We joke about these amps being rated in "ILS" which is If Lightening Strikes this amp it may do said wattage, lol. Old school thinking is that a decent amp is roughly $1 per watt, not even close to being scientific but is just a reference point. This has probably come down over the years but still a good reference.

Example
Hypothetically if a Boss amp sells for $69.00 and claims to output 1000 watts - i would use the amp for an anchor.

And this 1000 watt Boss amp would not compare to a JL 1000 watt amp selling for $999.99

[ssmith]

Thanks for all the input. Its beginning to make a bit more sense. I have the WS "Double Up" (should be here this Friday) and was trying to decide what to power it with to get the best sound without breaking the bank. I've decided to suck it up and power it with the Syn2 as several people have recommended to me. Its more $$ than I wanted to spend on an amp right now but hopefully I'll be satisfied with this setup.

[AirTool]

....Its more $$ than I wanted to spend on an amp right now but hopefully I'll be satisfied with this setup.

There is an old axiom we use in the offshore engineering business: "If you spend too much, you might waste a little money. If you don't spend enough, you waste all your money."

[bubba]

There is an old axiom we use in the offshore engineering business: "If you spend too much, you might waste a little money. If you don't spend enough, you waste all your money."

Yep, my moto is: "Buy quality and only Cry once."