Watts and Ohms

Hello Music Wizards

OK, so I am doing my homework on if I want to upgrade my speakers.

I now use two powered JBL Eon 10G2's with my Tyros. Sounds quite good. So far it has been plenty of power for my needs. But I've been thinking of having more in reserve for bigger rooms. Plus you all know we need to get new toys once in a while.

So with that in mind. My JBL's are 175 watts.

I have been thinking about the Peavey PR12's which are 8 ohms.

I have been checking out the Behringer PMX2000. This is 250 watts at 4 ohms and 180 watts at 8 ohms.

I have also been looking at the Behringer PMH880S. This is 2 x 400 watts at 4 ohms and 2 x 200 watts at 8 ohms.

So in checking the numbers:

JBLs 175 watts
PMX2000 180 watts
PMH880S 200 watts

If what I am looking at and deducing from these figures is correct, then really there may be no real reason to even make a switch with this combination. It appears to be a very small difference in power. I know the EV sx100+ are 200 watts also.

I know a little knowledge can be dangerous. This is not my area of expertice.

I also know that a bunch of numbers on a piece of paper is not as important as the sound itself.

Any comments to help clear up this topic up in my mind?

thanx
Scott

Scott,
You need to increase the wattage by TEN times to get twice the volume. That's right - TEN times.

My advice is to get a subwoofer - that will make the output of your eons more efficient and the dance floor will FEEL the punch that the 10s are missing.

Unlike men, all watts are not created equal. This is a widely researched subject, but different companies arrive at their wattage ratings in varying ways. Also important to consider is the efficiency of the speaker.
Use your ears and trust them.
DonM

Listen to Uncle Dave get the sub!!

Also take in consideration:
- the impedance load (ohms) effect the amp.
- the load depends on the wiring configuration of the speakers
- the amp has to be able to handle this load
- the lower the impedance, the higher the amperage, the higher the load
- too low of an impedance will damage your amp.

SOUNDS like detective work for Sherlock OHMs and Dr. WATTson.

I'm sorry. I am on my way to work right now and my mind gets this way whenever I try and gear up for that event. I apologize.

Good Day everyone.

Ed - That's a dreadful pun but very clever.

KFingers

Scott,


Typically consumer speakers are rated at 8 Ohm, most portable professional speakers at 4 Ohm, and stationary pro speakers (like in the concert halls) at 2 Ohm.

This is how 8 Ohm/4 Ohm rating is applicable, in the case of PMX2000:

If you plug in one set of speakers, rated 8 ohm, you get 180 watt sound output. If you plug in a second set of speakers (in parallel with the first one - some amps provide dual outputs), this halves the impedance to 4 ohm, but you do not get twice the power output, but only 250 Watt.

It follows that you have to match the impedance of speakers to the amp - for maximum output you should get 4 ohm speakers, or use 2 sets of 8 Ohm speakers. I would not recommend getting speakers with lower impedance than the amp is rated for (possible to damage the amp).

BTW, despite some posts to the contrary, I still believe that PMX2000 is a MONO mixer, as you can not pan the individual inputs to the right and left. If you think it sufficient for your needs - fine, but I would spend another $70 and buy a true stereo device.

Regards

I believe to get 250 watts out of the Berringer, you would need to either use a mono mode (if there is a stereo/mono capacity) and 2 8 ohm speakers, for a 4 ohm load, or use 4 8 ohm cabinets (two per side) in stereo mode.

Russ

It alsohas something to do with "decibels."
I don't know exactly how it works, but I remember that it takes twice the wattage to raise 100 decibels to 110 decibels, or something like that. Anyway, it's not just wattage, but decibels and distortion.

Get the sub-woofer.

The PMX-2000 is 500 Watts bridged and 180 Watts X (2) (Left/Right) @ 8 Ohms or 360 Watts total in Stereo Mode. See the manual for yourself http://www.behringer.com/PMH2000/index.cfm?lang=ENG

Whether you believe it or not the PMX is TRUE Stereo...All you have to do is Listen to the results out the speakers and you will agree. All my patches and my MP3 player are in True stereo.

When I play with my band 7 piece band, I never move the volume knob past 5. There is a lot of headroom with this AMP for a Keyboard Player.

I'm constantly amazed at someof the posts pertaining to wattage and impedience applications I read on this and other forums. Unfortunately, some posts are based on information put forth by manufacturers, much of which is hype for their product.

More often than not, the rating of their sound systems is based on peak power using low impedience speakers. Peak power is almost a meainingless term, almost like an engine rated at 1,000 HP. That 1,000 HP may not be developed until the engine reaches maximum RPM.

One thing that may help in this endeavor to garner information pertaining to sound systems is to apply Ohm's Law, which is the basis for determining all things electrical. You'll find a good example of this at http://www.angelfire.com/pa/baconbacon/page2.html The main thing that should be considered with all sound sytems, IMO, is RMS power, freqency response, frequency range, and last, physical speaker size.

Have Fun,

Gary

Question,

I thought that the amp needed to be less than the speakers in order to make sure you don't damage the speaker. Like if you have 175 speakers, shouldn't that be the maximum wattage output the amp should be able to produce and not go over that?

JBLs 175 watts
PMX2000 180 watts
PMH880S 200 watts


Thanks
Bob
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It's the combination of amps and volts that create wattage. The basic formula is I=E/R which is from the old school of learning. I is the current in amperes, E is the voltage and R is the resitance.

The forumla for determining power in watts usind direct currnt is P=EI=RI 2.

Gary

My formula is...if you smell or see smoke, the amp and speakers are not compatible..

Hey Bob

I reckon so, but the JBL's at 175 watts that I now own are powered speakers. I just used that as a comparison. Wondering if it was really worth me getting something that is only a few more watts, if those figures are in fact arrived at the same way.

Scott

Originally posted by Scott Langholff:


Scott, the info on speakers is very much like the political scene -- who's telling the truth? I have a Ampeg bass amp rated at 25 Watts witch sounds clearer and louder than a fender rated at 125 Watts.
Bottom line is to listen and decide -- use the info only as a gentle guide.

The JBL 10"s -- powered, sound great, a good full warm sound. I am inclined to agree with Dave --- Sub-woofer and you have it all. If you are talking about very large crowds (400 and up), then you need bigger speakers and lot more wattage.

Don't sell um, John C.

I believe that the self-powered speakers are louder and more efficient "per watt" than unpowered, proably because each speaker has a dedicated amp that is expressly designed for maximum efficiency.
DonM