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4 or 8 Ohm speakers?

 

Anonymous
 
Ok, this is actually about a small PA system for use by a gigging pub band, but I'm guessing my question can be answered here...I hope so because nowhere else seems to explain it for stupid guys like me! Basically, I'm purchasing a power amplifier, and part of the specification runs like this:

300W 2-channel power amp
------------------------
OUTPUT POWER IN WATTS
200W @ 8 ohms per channel
300W @ 4 ohms per channel
600W 8 ohm bridged operation

Now, basically, I'm planning on purchasing two passive speakers to plug into this amp. My question is, what would be better: two 4 ohm speakers that can handle 300W, or two 8 ohm speakers that can handle 200W? I want plenty of volume and decent sound quality. My current plan is to go for two 8 ohm 300W speakers to allow for future upgrading; would this be a good idea?
 

Bronze Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 70
Registered: Feb-04
The difference in sound produced between 200 and 300 W is the same as between 2 and 3 W. It's about 1.8 dB and 1 dB is barely perceptible. I wouldn't worry about such a small difference.
 

Anonymous
 
so are there any advantage to using 4ohm speakers? Better details ????
 

Bronze Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 73
Registered: Feb-04
4-ohm speakers are not intrinsingly better than 8 ohms, however not all amplifiers can drive them because of the higher current needed.

For the same voltage from the amplifier, a 4-ohm speaker will request twice the current and power.
 

Anony
Unregistered guest
Lol that second anonymous post wasn't me...I assume someone else is in the same dilemma...oh well, no trouble :-)

The amplifier definitely can drive speakers at 4 ohms, so is there any advantage to going for them? Basically, my question comes down to this: should I buy two 8 ohm speakers that take up to 350W (future upgradeability ;). I can find speakers with those specs for £130; for the same price I can get 250W 4 ohm speakers. I'm guessing I couldn't get 250W because it would be risky at high volumes due to the specs of the amp. However prices seem to increase steeply after that.
 

Bronze Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 98
Registered: Feb-04
Anony,

I personally don't think you should be buying speakers based on power handling. First, typical variations in speaker efficiency will yield a bigger change in sound pressure. Second, power handling is not a good indicator of good sound. Third, it's difficult to assess how much clean power a speaker can take because peak power is generally in short peaks at low frequencies. For example, my speakers were said to handle 100W RMS but peaks of 1000W. It's just not a very useful measure.
 

Anonymous
 
Cheers Pete :-) ok then, well my question is just this: 4ohm or 8ohm speakers?
 

Silver Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 101
Registered: Feb-04
You are in the position to buy the best speaker you can find regardless of the ohm rating. A lot of people would have to cross 4 ohm speakers off their list because their amp can't drive them. So simply forget that factor and listen to different speakers in your price range to find the best sounding.

Keep in mind that you may change amplifiers one day to something that can't drive 4 ohms...
 

Daniel Benatar
Unregistered guest
I think that with the time, more and more speakers will move to 4 ohm. For example, NAD receiver will perform better with 4 ohm - better sound performance. The high end amp and pre amp will drive 4 ohm speakers better with better dynamic and cleaner sound.

Be sure that your amp is capable to drive 4 ohm as if not it will be damaged.

Good luck, Daniel
 

Anony
Unregistered guest
I can't seem to find many 4 ohm speakers in my price range which can take 300W...I'm looking at around £150 per speaker, two speakers, and a decent SPL (at least 98DBSPL 1w/1m). Am I right in thinking SPL is a relatively important factor?
 

Daniel Benatar
Unregistered guest
In 4 ohm speakers you will find better materials, and therefore, I don't think you will find a good 4 ohm speaker at this price range.

Anywat, goodluck, Daniel
 

Silver Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 108
Registered: Feb-04
Anony,

Yes, sensitivity or efficiency is an important factor to consider. For every 3 dB, there's a doubling of power. So a 98 dB efficiency speaker needs 1/8th of the power as an 89 dB efficiency speaker to attain the same sound pressure.

But higher efficiency does not necessarily mean better sound.

Klipsch speakers are efficient, but they are beyond your budget I would think.
 

Silver Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 109
Registered: Feb-04
Anony,

Why are you insisting on finding a speaker that will take 300W anyway?
 

New member
Username: Djflannel

Crofton, Maryland United State...

Post Number: 1
Registered: Oct-04
Uh, hey, i think i'm a little screwed in a situation i've got goin on.
I was literally JUST on ebay and went a little trigger happy, and bought two speakers, overlooking their 4 ohm thingy. These are dual 12" woofer speakers, and i wanted to run at least 100 watts through them using an 8ohm amplifier. DOes this mean i will only get 50 watts?!?!? I'm only 16, i don't get much money, so these will be the speakers i'm gonna be stuck with for a while--- any hope of me gettin 100 watts through to DJ the school dance?!?!?
 

New member
Username: Djflannel

Crofton, Maryland United State...

Post Number: 2
Registered: Oct-04
Hold on, i just read a message up above that says 4 ohm speakers can DAMAGE an 8 ohm amplifier??? Will the autoshutoff protect my amp?!?!? MY amplifier is a KLH-R5100 Surround Reciever. 500 watts thru 5, sub lineout
 

Silver Member
Username: Petergalbraith

Rimouski, Quebec Canada

Post Number: 122
Registered: Feb-04
FKW,

If a 100W receiver can drive 4 ohm speaker perfectly, it will do so at 200W per channel; not 50W.

Do not assume that 100W is a magic number for a school dance. It all depends on how efficient the speakers are (usually expressed as how many decibels (dB) with 1W input and measured at 1m).

Will a receiver that can't really do 4 ohms be damaged? Possibly, but more likely it might just sound flat, with little dynamics and little bass.

 

New member
Username: Djflannel

Crofton, Maryland United State...

Post Number: 3
Registered: Oct-04
Frankie here,
So, overall is there much to worry about?- am i over-reacting?
And if my amplifier does get damaged, would you know in what way it would be damaged?- signal, output, functions, ???

thanks


 

New member
Username: Djflannel

Crofton, Maryland United State...

Post Number: 4
Registered: Oct-04
Uh, another concern for my speakers- I didn't take a close enough look at the pictures, and now i don't know if the rear connectors on the speakers are bare wire push terminals, or 1'4" pro connectors- My amp hooks up with push-terminals, not 1/4", so is this "the end?"
I was wondering if i could buy 1'4" speaker cable, cut off one end of the cable- strip the insulation, and use that end like speaker wire, into my amplifier- Is this a BAD idea? So far, I don't see why this wouldn't work- Could this cause damage to my speakers or amp in some mysterious way?
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