What Power Output Am I Getting?

[DJK 0]

TOPIC MOVED TO CORRECt AREA

Hello everyone

I have a yamaha emx5000 powered mixer with 2x 350w tops and 2x 350 watt bass speakers, if i run the amp at full am i getting 500w per side? it just doesnt seem to be loud enough sometimes, i have to run the amp at full when the bass speakers are plugged in.

someone mentioned something about ohms, but i don't really understand it. when all the 4 speakers are plugged in does the power get distributed to different speakers evenly? or does 350w per side go to the tops and 150w per side go to the bass?

sorry if it's a stupid question, but i just don't get it

thanks for any help offered.

[Gary 0]

For me, running the amp (your Master volume?) at full is scary - one wrong move elsewhere on the mixer, or as I've seen happen, the raffle lady dropping your mic on the floor >THWUMP

 

Ideally, as you've got 4 x 350 watt speakers, (1400 watts), you should have around 2000+ watts in amplifiers - so that the amplifierss are just "ticking over". A nice analogy of this is the car engine/speed idea. Say a cars engine says its max speed is 160mph, if you drove everywhere at 160mph you'd get nicked your engine would be straining its guts out to match your request.

 

Whereas, if your engines top speed was 250mph and you drove everywhere at 160mph you'd still get nicked but your engine would be a heck of a lot happier.

 

I really wouldn't recommend trying to pull 500watts out of a 500watt amp, not for an entire evening anyway, not even for an entire evening of peaks (bass beats etc).

 

There is, unfortunately, another layer/level to the whole speakers/amps/wattage story, and you've already mentioned it briefly - Ohms.

 

To offer specific advice on your set-up, we'd really need to know the OHMs (impedence) of each of the speakers, and the amp (the amp might have 2 or 3 variations, knowing all of them would be handy - for example - the amp label/manual might say something like....

 

500watts @ 4ohms (per channel/side - if its Stereo)

250watts @ 8ohms (per channel/side - if its Stereo)

 

 

The speakers should just have one rating on them -eg:

 

350watts @ 8ohms.

 

 

BUT...if your speakers get joined together using simple daisy chaining - eg: two identical looking sockets on the back, where the amp goes to the first speaker, then the first speaker gets connected to the second - then two 8ohm speakers connected together show themselves (oh err missus) to the amp as a 4ohm speaker/load.

 

So...say your powered mixer is 500watts into 4ohms (per channel / side) and lets say that your speakers are each 8 ohms daisy-chained together. The amp will see a single load/speaker of 4ohms.

 

 

What I'd suggest as you're not finding it loud enough and are pushing the internal amp, is to use the internal amp just to power the "top" speakers, and then buy yourself an amp just to run the bass speakers. This way, you'd have 4 speakers and 4 "outs" from the amps, and neither amp would be straining - both amps just running "nice".

Edited April 1, 2008 by Gary

[UKHero 0]

For me, running the amp (your Master volume?) at full is scary - one wrong move elsewhere on the mixer, or as I've seen happen, the raffle lady dropping your mic on the floor >THWUMP< and your speakers could getting the full 500w.

 

Ideally, as you've got 4 x 350 watt speakers, (1400 watts), you should have around 2000+ watts in amplifiers - so that the amplifierss are just "ticking over". A nice analogy of this is the car engine/speed idea. Say a cars engine says its max speed is 160mph, if you drove everywhere at 160mph you'd get nicked your engine would be straining its guts out to match your request.

 

Whereas, if your engines top speed was 250mph and you drove everywhere at 160mph you'd still get nicked but your engine would be a heck of a lot happier.

 

I really wouldn't recommend trying to pull 500watts out of a 500watt amp, not for an entire evening anyway, not even for an entire evening of peaks (bass beats etc).

 

There is, unfortunately, another layer/level to the whole speakers/amps/wattage story, and you've already mentioned it briefly - Ohms.

 

To offer specific advice on your set-up, we'd really need to know the OHMs (impedence) of each of the speakers, and the amp (the amp might have 2 or 3 variations, knowing all of them would be handy - for example - the amp label/manual might say something like....

 

500watts @ 4ohms (per channel/side - if its Stereo)

250watts @ 8ohms (per channel/side - if its Stereo)

The speakers should just have one rating on them -eg:

 

350watts @ 8ohms.

BUT...if your speakers get joined together using simple daisy chaining - eg: two identical looking sockets on the back, where the amp goes to the first speaker, then the first speaker gets connected to the second - then two 8ohm speakers connected together show themselves (oh err missus) to the amp as a 4ohm speaker/load.

 

So...say your powered mixer is 500watts into 4ohms (per channel / side) and lets say that your speakers are each 8 ohms daisy-chained together. The amp will see a single load/speaker of 4ohms.

What I'd suggest as you're not finding it loud enough and are pushing the internal amp, is to use the internal amp just to power the "top" speakers, and then buy yourself an amp just to run the bass speakers. This way, you'd have 4 speakers and 4 "outs" from the amps, and neither amp would be straining - both amps just running "nice".

 

 

you have opened a can of worms here as Gary is right but also wrong and the next poster will probably say the same about me..

 

Dependant on your bass bins your amp might only see 8 Ohm with both tops linked to your subs. ie out of amp into bass or sub unit then link from sub into mid top speakers. if there is a cross over in the sub then the amp will see 8ohm even though Gary is right that when you link two 8 ohm speakers in parallel they will be seen as 4 ohm.. But a cross over hides the second speaker and just showes up as 8 ohm...

 

 

As for the double the amp power to speaker rating and the car analogie, and we can all use different analogies to prove many points right or wrong.

 

If a speaker is rated at 350 RMS then that is the maximum it should be fed, better quality speakers will have more tollerence to peaks above this. A slave amp delivers the potential to its speaker at all times ie the volume controle is on the pre amp side...

 

So if you connect a 500 watt amp to a 350 watt speaker the amp has the potential to deliver 500 watts to that speaker at any time. You are mearly limiting the volume going into the amp not the power coming out.

 

I agree with Gary that you should not drive your amps to excess all the time and so need to invest in an amp or amps and speakers that will be well above your expected requirements.

 

For example if you had a 2000 watt amp into 5000 watts of speakers but only feed a signal to drive the speakers upto say 1000 watt then all would be fine. But if you had a 500 watt amp and a 350 watt speaker and continualy pushed the amp to max then eventually something would give, most likley the speaker.

 

As I say this is a can of worms and there are many thought as to the right way to run your amps etc..

 

A good gain structure is also important for good safe and clear sound...

 

Nik

 

[Robster 0]

err as far as i know (and thats not a lot) amp wattages and impedance are not a real accurate indication of how loud it will sound.

Sound pressure level will tell you how loud something is . Sensitivity and impedance of the speakers the Amplifiers current capability not just measurement of wattage and the room acoustics have a great influence on how loud you will perceive the system.

 

running the system on full is as others have said not the way i would do it. you need a more powerful amp if you want it to sound louder and not one that just just gives a wattage figure without telling you its RMS across the audible spectrum and at what level of THD its rated at. the other way is to get more sensitive speakers if you want it to sound louder.

 

but hey whatta i know i might be completely wrong!!!

Edited April 1, 2008 by enquirer

[TonyB 0]

Looking at the spec of your amp, it is 500w at 4 Ohms and 325w at 8 Ohms

 

As Nik says, if the bass bins have a crossover that balances the impedance when you connect tops to it, there is a chance that the system is running at 8 Ohms which is 325w a channel. Different manufacturers do it in different ways but a general rule of thumb is if the bass bins have one speaker socket marked as "input" and the other one marked as "output" then then the amp will see the impedance of the bass bins irrespective of whether tops are added or not e.g. if the bass bins are 8 Ohms, adding 8 Ohm tops will still give an impedance of 8 ohms.

 

If you can plug the speaker lead into either socket on the bass bins then the impedance is worked out using the "connected in parallel" formula e.g. if the bass bins are 8 Ohms adding 8 Ohm tops will give an impedance of 4 Ohms.

 

It does vary from manufacturer to manufacturer so it is best to check the speaker manual to confirm how they do it.

 

With regards to how much power goes to each speaker, two identical speakers connected in parallel will share the power equally. So if the amp outputs 500w, they would get 250w each.

 

Using bass bins and tops, alters this a bit because the lower frequencies use more power than the higher ones. It depends on what the crossover frequency is. A lower frequency will mean the tops are handling more of the lower frequencies, and I find that at about 90hz the power split is roughly 50/50. At 180hz the bass bins seem to use roughly 2/3rds of the power compared to the tops 1/3rd. It also depends on what sort of music is playing, music with a heavy bass line will mean that the bass bins will consume more power than music with less of a bass line.

 

Probably the easiest way to give you more volume is to get another amp for the bass bins and plug it into the ST SUB OUT sockets. Won't be ideal because the tops will still be running full range but there not a lot you can do about that using a mixer amp.

[nigelwright7557 0]

Is really important to match the speakers to your amplifier.

If the amp gives most power into 4 ohms then use that otherwise you need a bigger amp.

 

I have seen people just parallelling speakers up and end up with 2 ohms or less.

The amp power supply supplys so many volts at so many amps so you must stay inside those limits.

This is where the 8ohms and 4ohms spec comes from.

 

If you use to high an impedance there wont be enough volts to output full power.

If you use too low an impedance the amp power supply will run out of amps before the max volts is reached and will probably blow the fuses.

 

I would never ever have an amp with more power than the speakers.

I worked in an audio repair shop for a while and replaced more speakers than I care to mention because of people over driving them.

 

An often overlooked thing is the sensitivity of the speakers.

This is usually speced in db i.e. 80db to 110db, the higher the figure the louder the speaker.

I have seen good 50 watt speakers outperform 100 watt speakers due solely to better sensitivity.

This is why I build my own speaker boxes and buy the most sensitive speakers for them.

 

There is little point having massive watts if all the speaker does is convert the watts to heat instead of magnetic flux.

Edited April 1, 2008 by nigelwright7557

[norty303 0]

I would never ever have an amp with more power than the speakers.

I worked in an audio repair shop for a while and replaced more speakers than I care to mention because of people over driving them.

 

But to be fair, you don't know HOW they were over pwering them.

 

Amps bigger than speakers are fine, but need to be used within limits. A clipping amp will kill a speaker if its the same power of more, so its incorrect use that kils the speaker, not neccessarily the size.

 

As you say sensitivity is important, in fact i think its THE spec to be looking at. Thats why most pro audio systems are horn loaded, or clever narrow bandwidth ported designs, because it gets the most out the amp and driver.

 

As for turning the amp down, it s been said before and I don't have the time to repeat it or inclination, but your amp can deliver its full power regardless of knob position 9aprt from off obviously!)

 

If you're worried about mic drops and thumps then you should be using a limiter to catch these sorts of things, but in my experience most failures are due to sustained high power, either with distorted signal and/or clipping causing the voice coil to fry. Mechanical failures or the spider/cone are much rarer and tend to happen in cabs where the driver is under a lot of stress such as a high compression horn.

 

Other causes of failure are from drivers becoming unloaded in ported cabs due to exessive EQ below tuning frequency, or not using high pass filters to remove ultra lows. i think the reason why mobile jocks suffer blow ups as much as they do (and sweeping generalisation here....) is because they use simply a mixer into amp into speaker setup, so the cabs are not protected from very low frequencies, sudden gain increases or heavily clipping amps at all.

 

Look at a pro audio rack for a system and you'll see a range of kit, from limters, filters, etc which are not just flash, they are there to do a specific job, and as a result you get much higher performance and longevity.

 

The Behringer DCX2496 is such a great unit as it makes these sorts of features accessible to everyone, and i'm sure most people would notice much improvement using one on even the simplest rig

[Robster 0]

In our service dept we found it was distorted music from amps clipping and being over driven and not clean signal from much more powerful amps that blew speakers .

mission the hi fi speaker manufacturer used to have a little booklet that said there 100wts rated speakers could happily be ran by 600wts quality amps fed with master tape quality source and would not blow.. but a 30Watt Technics amp often blew them driven into clipping in our experience.

 

sensitivity of speakers is key to how loud it will sound in my experience but you also need a quality amp with plenty of current capability if you want it to be a reliable set up.

[UKHero 0]

an any one tell me what is the point of rating speakers and amps if you are ok or supossed to put higher reated amps with lower rated speakers.. I just dont get it.. I understand the clipping thing but then thats because you should have a more powerfull set up if you need more sound.. As I said above if you need say 1000 Watts and you have a 2000 watt amp with 4000 watt speakers surely this is better than having 1000 watts with say a 700 watt speaker.

 

Analogie time again. :ads: If you come to a bridge that says maximum gross weight 5 ton and you are 8 ton do you cross?? Chances are you will be OK because the bridge company will have allowed for the odd heavy vehicle to cross it for safety and reliability reasons. How ever if all vehicles trundled over that bridge at 8 tons all day every day the bridge would eventualy become stressed and fail. The weight restriction was put there for a reason. And so I assume the ratings on amps and spaeakers are...

 

Also as said above you need a good gain structure once distortion is added to a signal it can not be removed. So unless your a lead guitarist in a rock band set up the gains from Laptop HDC CD or Deck to mixer to EQ to amp correctly...

 

 

Nik

 

[Robster 0]

an any one tell me what is the point of rating speakers and amps if you are ok or supossed to put higher reated amps with lower rated speakers.. I just dont get it.. I understand the clipping thing but then thats because you should have a more powerfull set up if you need more sound.. As I said above if you need say 1000 Watts and you have a 2000 watt amp with 4000 watt speakers surely this is better than having 1000 watts with say a 700 watt speaker.

 

 

It was explained to me like this ..measurements in electronics are not just one statement wattage on amps is open to various criteria so one amp can quite happily say its 500watts legally and another say its 500watts legally but is measured with 10% distortion at just one frequency say 1KZ the other is measured at 1% distortion over 20hz to 20Khz now we know which one is more likely to sound better but both are 500watts

 

analogie

a Ferrari and a 2CV are going 90 miles an hour down the Autobahn one is about to blow up the other is cruising comfortably with more speed in reserve if you wanted it ...BUT if you measured them they are both doing 90 miles an hour the 90 miles an hour figure can not be trusted as a speed for the 2CV but they can legally say it can do 90.

 

Now with speakers a similar thing happens the rating of the speaker and i am talking about complete speaker cabinets not the component drivers themselves is what the manufacturer says the speaker can take(obviously unclipped distorted power) ..not what it outputs! we do not hear wattage the measurement is dB spl

Bose interaudio speakers for example used to put a filament resistor inside there speakers (better known as a bulb) so when you turned it up to the bulb glowed inside to take excess power away from the tweeter, a crossover often has parts in it to protect the drivers , the figure on the back has no real bearing on the Quality of sound or loudness. sensitivity is an indication of how loud a speaker will sound but again loudness has no bearing on the quality of sound.. a plane taking off is loud but i don,t want to listen to that all day.

 

The quality brands of equipment tend to rate there products better , they show more conservative measurements with better tolerances ,cheaper brands do the opposite so the truth is its near impossible to choose a set up from facts and figures spec sheets unless they fully print the specs and you know and trust the brands reputation , the best way to choose is to listen your self to the equipment before you buy and listen to friends who use the gear they recommend or from staff at quality stores who can demonstrate the products.

 

Crown who make quality amps say between 1.6X and 2.5x the continuous power handling of the speaker is the power rating of amp you need for headroom

http://www.crownaudio.com/amp_htm/amp_info..._much_power.htm

 

As i said i have never seen a speaker blown from too much power but i have seen many from smaller amps over driven

Edited April 2, 2008 by enquirer

[TonyB 0]

This is a subject that gets debated until the cows come home!

 

The suggestion of it being a good idea to have a more powerful amplifier than speakers is because of "head room".

 

For example, a 300w rms speaker can usually handle short term peaks of 4 times its RMS rating i.e. 1200w

 

A 300w amplifier cannot supply enough watts to cleanly provide power for any transient peaks up to the 1200w. According to the Crown link, an amplifiers RMS and peak power are nearly the same. At best it will allow 1db for peaks but transient peaks can be up to 25db or more.

 

It is therefore recommended that a more powerful amp is used to have some power in reserve (headroom) for the transient peaks.

 

Using a more powerful amp doesn't mean that it will be any louder. For example, if the speakers are 300w RMS and a 600w amp is used, the volume should be at the same level as it would be if you used a 300w amp. The extra 300w is the "head room".

 

The problem is:

 

1) Most DJ's have no way of knowing how much power they are pumping into the speakers and are likely to pump more than 300w rms into them

2) If the power is there, there is a temptation to use it.

3) If you clip the amp, drop a mic or get feedback with a 600w amp connected, you are more likely to damage the speakers because of the extra power.

 

As it says on the Crown site quote"If you cant keep the power amp from clipping (say, you have no limiter and the system is overdriven or goes into feedback) the amplifier power should equal the speakers continuous power rating"

 

So basically you should only use a more powerful amp if you have a limiter and you can be careful enough not to push more power than the speaker RMS power rating in to it.

 

Using the Enquirers analogy, if the engine is represented by the amp and the rest of the vehicle is the speakers:

 

A 300w amp with 300w speakers is like the the 2CV that will do 90mph

 

A 600w amp with 300w speakers is like the 2CV fitted with a Ferrari engine, i.e. it is still only safe to do 90mph in it because the transmission, suspension, tyres, brakes, bodywork etc won't cope with anymore but the ride will be a little less stressful

 

A 600w amp with 600w speakers is like the Ferrari and will happily cruise at 125mph

 

It is also interesting that active speaker manufacturers such as Mackie match amp and speakers. The transducer (main speaker) in a Mackie SRM450 is 300w RMS and the amplifier powering it is 300w RMS. So if its good enough for one of the worlds top selling speakers, its good enough for me smile icon

Edited April 2, 2008 by TonyB

[nigelwright7557 0]

But to be fair, you don't know HOW they were over pwering them.

 

 

I always talked to the customers to ensure the problem didnt happen again.

If I simply replaced the speaker and they were back next week with the same problem I would have got seriously slated for that !

 

In every case it was pure overdriving speakers with too big an amp.

 

A speaker coil is like a resistor in electronics.

It will take transients but not continuously.

It will get to a point where voice coil overheats and melts the insulation and the speaker goes low ohms or even short circuit.

I have ripped quite a few failed speakers apart and the voice coil is always cooked.

I havent as yet seen an open circuit speaker.

 

[UKHero 0]

 

A 600w amp with 600w speakers is like the Ferrari and will happily cruise at 125mph

 

 

Surely then my example of a 1000 watt amp with a 2000 watt speaker is like a Rolls then. Plenty of speed if needed but a body built beyond expectations.

[norty303 0]

But will never achieve it's full potential due to not having enough power to move the heavy body effectively.

 

 

 

[BK Sound 0]

To protect your expensive speakers from damage.....Formula Sound make a product called an AVC2 - its a 1U rackmounted "automatic volume control"...if Mr DJ turns the mixer volume up too high, the AVC2 turns is back down to its preset level until the dj turns it down again...this is not a compressor/limiter so you dont get nasty pumping effects, its pretty much unnoticable in use.

 

I run my 600 watt AES subs with 1000 watts AES

I dry hire the system out, unmanned all night.

The system is used for raves, bands & disco/karaoke

In 5 years of owning it i have never had to replace a driver

 

Expensive but check ebay, about £120-150 used, worth every penny.

 

AVC2 Product Page

 

 

to the OP - put a multimeter set to "ohms" at the amp end of your speaker cable across the 2 terminals and you'll get a reading of the load your amp will be seeing.

 

 

 

 

 

 

[EdBray 0]

to the OP - put a multimeter set to "ohms" at the amp end of your speaker cable across the 2 terminals and you'll get a reading of the load your amp will be seeing.

Don't think you will, the speaker coil resistance(impedence) will be measured using an AC current, not a DC one as will be given by a multimeter. It will give a false reading on a multimeter.

[UKHero 0]

But will never achieve it's full potential due to not having enough power to move the heavy body effectively.

 

No I agree but in turms of the speaker if you dont want to push them then they will never reach there full potential any ways... If you need to do 125 MPH and your Rolls can easilly do 175 MPH you know you are safe. ok you might be able to supercharge the engine so the body could get to its full potential of say 225 MPH, but would it last as long and be as safe. Cue magic round about theme... :dan+ju:

 

Nik

 

[BK Sound 0]

Don't think you will, the speaker coil resistance(impedence) will be measured using an AC current, not a DC one as will be given by a multimeter. It will give a false reading on a multimeter.

 

You're probably right about the ac/dc thing, i'm not technician so i'm not gonna argue the complexities with you...however....

 

I've just put a 3 seperate multimeters across an 8 ohm load and got a 7.8 ohm reading, then across a 4 ohm load i got a 4.0 reading, tried this on several speaker drivers & commercially made speaker cabs.

 

It might not be 100% accurate but it will give the OP an approximation...and most importantly he should be able to see if adding the bass bins reduces the load or it stays the same, which answers that crossover question.

 

 

 

[Robster 0]

I agree with nik this is magic roundabout ..my analogie was for the AMP ONLY not the speakers being the suspension etc it was to describe how not all 500 watt amps are the same.. quality does count

 

Many companies have found new, convenient ways to get "big" wattage ratings on their amplifiers. They may take one frequency or tone (1kHz) and push it through one channel of amplification. This way the power supply only needs to supply power to one tone and one channel (no one listens to one tone through one speaker). This is not a difficult task for a power supply, so you get a nice, high rating like 100 watts. Now let's feed that one tone (1kHz) into 2 channels. Now the power supply has to supply power to 2 channels. The wattage rating is drastically reduced. Now let's take that one tone and make it ALL tones (pink noise). The power supply now has to supply power to all frequencies in both channels. Again, the wattage rating is drastically reduced. Now, your 100-watt amp is suddenly 50 watts (approximately).

 

Let's take it one step further. When you turn the amp up and begin to average the 50 watts of power, what happens to all of the dynamics/peaks in the sound? It can't get any louder, because the amp has hit its "ceiling," so the sound gets "clipped." The human ear typically can?t hear this clipping because peaks pass by so quickly but, nonetheless, the dynamics are gone.

 

 

Quality manufacturers still rate amplifiers the old-fashioned way - all frequencies with both channels driven. So "50 watts" is 50 watts. Twenty-five years ago, a 50-watt amp was very powerful. These days you can go to a store and hear a "500 watt" Amplifier and it won't impress; it lacks dynamic punch.

 

Now if you take it that extra step. When you turn the amp up and begin to average the 50 watts of power, the amp still needs to put out much more power every time a snare drum etc hits. Quality amps are able to instantaneously put out Extra amps of high current to the speakers, allowing those dynamics to come through loud and clear, without any distortion. This brings the overall decibel average up, making it seem even louder that 50-watts.

That's all i was saying with my analogie nothing about the speakers

 

moving on to speakers...

 

A speakers impedance is not the same when music is played thorough it .

a speaker is not a fixed resistor. some manufacturers lable them having a "nominal" impedance Such a nominal value may often be different from the actual value, having a relation to the actual value that is anywhere on a spectrum from closely related to only distantly related.

The impedance of the speaker varies when you play music through it.

If you measure it when its silent with no music playing that's not really catching a speaker in its natural environment so to speak.

some speakers can present an awkward load on some amps when trying to produce certain frequencies if the amp is a quality one it is very likely it can handle it .If the amp is poor quality then its likely that it won't handle that load as well.

 

active speaker systems work well as the manufacturer can match the speaker and the amp and if they want to they can introduce limiting electronics so they know the speakers wont blow increasing reliability.

 

This is a groundhog day debate that will always pop up because there are valid arguments on the many facets of the topic.

[norty303 0]

Formula Sound make a product called an AVC2

 

My favourite piece of kit in the rack!

 

Affords me the opportunity to NOT have to babysit DJ's with poor technique/knowledge for 12 hour stints!

 

 

The only thing that I'd add to enquirers post about impedance/nominal impedance is the way that the driver loading can change the impedence. Reflex boxes have impedance spikes at points above the port tuning frequency. This is not normally too much of a problem as it occurs over a narrow band. Where a bandpass box is employed with a very narrow bandwidth tuning these can be very close together and change the impedance for the cab over most of its operating range.

 

Horns can also significantly change the nominal impedance of a cab, compared to the driver rating.