Bought mixer, what speakers?

[Mr. C]

I just purchased a Yamaha EMX 2300 mixer and read that it puts out 250 watts per channel at 4 ohms. So I've been looking around for speakers within my budget which would match this. Everything I look at seems to be rated at 8 ohms. I'm quite confused here because I don't understand the ohms ratings and I'm not sure what to buy. Any help?

[gbondo9]

What's your budget?

[pandamonk]

An amp usually puts out 4ohm and 8 ohm. It's just that it's 250w 4ohm, and probably 150w 8ohm. What are you using it for, studio or live? If for studio, you could get a pair of Behringer B2031P Truths, 150w 4ohm. If for live you could get something like a pair of these 250rms 4ohm, or even these 180w rms 8ohm.

Wait for someone elses advice though, I'm a bit confused by this too.

[pandamonk]

...double post...

[Simman]

Originally Posted by pandamonk

An amp usually puts out 4ohm and 8 ohm. It's just that it's 250w 4ohm, and probably 150w 8ohm. What are you using it for, studio or live? If for studio, you could get a pair of Behringer B2031P Truths, 150w 4ohm. If for live you could get something like a pair of these 250rms 4ohm, or even these 180w rms 8ohm.

Wait for someone elses advice though, I'm a bit confused by this too.

Amps do not put out 4 or 8 ohms of anything. 4 & 8 ohms refers to impedance values. Research Ohm's law. When dealing with power (watts) ratings of an amp, the impedance of the load (in this case speakers) is going to inversely effect power output; meaning if the load increases the power decreases. This will become évident when looking at the formulas for calculating power. There are other properties (voltage & current sink & source capabilities of the ouput stage circuity) but that is another story.


Bottom line is most commercial amps don't have an issue dealing with 4 & 8 ohm impedance, you will simply have the potential for more or less output power depending on the load.

[pandamonk]

Originally Posted by Simman

Amps do not put out 4 or 8 ohms of anything. 4 & 8 ohms refers to impedance values. Research Ohm's law. When dealing with power (watts) ratings of an amp, the impedance of the load (in this case speakers) is going to inversely effect power output; meaning if the load increases the power decreases. This will become évident when looking at the formulas for calculating power. There are other properties (voltage & current sink & source capabilities of the ouput stage circuity) but that is another story.


Bottom line is most commercial amps don't have an issue dealing with 4 & 8 ohm impedance, you will simply have the potential for more or less output power depending on the load.

Yeah i realised this as i posted it. I really said it for simplicity. I meant that they are rated for whatever wattage for whatever ohm, and most are fine with 4 and 8. Sorry for the misunderstanding.

Also do you mean that the amp works harder to power 8ohm than 4ohm, that is why the power is reduced?

[Lt. Bob]

because 8ohms is more resistance to the current flowing thru it thus, the amp doesn't manage to put out as much.
It's like how much water you can put thru a 1" hose (8 ohms) as opposed to how much'll go thru a 2" hose (4 ohms)

[pandamonk]

Originally Posted by Lt. Bob

because 8ohms is more resistance to the current flowing thru it thus, the amp doesn't manage to put out as much.
It's like how much water you can put thru a 1" hose (8 ohms) as opposed to how much'll go thru a 2" hose (4 ohms)

So doesn't that mean the amp works just as hard to power the 8ohm as 4ohm? Or it doesn't because it can't? Is it not better to use a 4ohm speaker then?

[Simman]

Originally Posted by pandamonk

So doesn't that mean the amp works just as hard to power the 8ohm as 4ohm? Or it doesn't because it can't? Is it not better to use a 4ohm speaker then?

The answer is not that simple; depends on the amplifier design. However, the most obvious result of the "work" as it relates to your question, will be heat.

[Lt. Bob]

well ...... I don't totally agree that the amp works 'harder' into 4 ohms if it's rated to run into 4 ohms.
However there are a few issues.
1. IF the amp has a marginal power supply it's not impossible that it might be working at the edge of its' capabilities trying to produce enough current to satisfy that maximum power rating and that's not uncommon with cheaper amps although something of quality like a Crown or any other name brand should be perfectly happy running into any load it's rated for.
But for those amps that are right on the edge ...... well, obviously that could lead to a greater possibility of failure.
Also ...... the difference in volume between 150 watts and 250 watts is not as much as you might think. It takes ten times the power to double the volume .... so to get twice as loud as 150 watts'll go, you need 1500 watts!

Also if you get 4 ohm speakers you won't be able to daisy chain them most of the time. A few amps like my Crown Power Base are rated to 2 ohms but most are not. And though you say right now you wouldn't want to daisychain them, how do you know a situation will never ever come up where you need that?
So just for versatility I think I'd go for 8 ohms if I were you.
Now, to be clear, I personally have a set of 4 ohm speakers I picked specifically for the reasons you're comtemplating doing so; so your reasoning isn't off that much. But I have Crowns doing the power thing and also I know a lot about hooking up systems. It sounds like you're still learning and so my advice would be to go the safe route and just get 8 ohms. If you want more later ..... then you can get a second set of speakers which will, when daisy chained, give you the higher power and having 4 speakers instead of two will give you a more noticable volume increase than using 2 4ohm speakers.

[pandamonk]

Originally Posted by Lt. Bob

well ...... I don't totally agree that the amp works 'harder' into 4 ohms if it's rated to run into 4 ohms.
However there are a few issues.
1. IF the amp has a marginal power supply it's not impossible that it might be working at the edge of its' capabilities trying to produce enough current to satisfy that maximum power rating and that's not uncommon with cheaper amps although something of quality like a Crown or any other name brand should be perfectly happy running into any load it's rated for.
But for those amps that are right on the edge ...... well, obviously that could lead to a greater possibility of failure.
Also ...... the difference in volume between 150 watts and 250 watts is not as much as you might think. It takes ten times the power to double the volume .... so to get twice as loud as 150 watts'll go, you need 1500 watts!

Also if you get 4 ohm speakers you won't be able to daisy chain them most of the time. A few amps like my Crown Power Base are rated to 2 ohms but most are not. And though you say right now you wouldn't want to daisychain them, how do you know a situation will never ever come up where you need that?
So just for versatility I think I'd go for 8 ohms if I were you.
Now, to be clear, I personally have a set of 4 ohm speakers I picked specifically for the reasons you're comtemplating doing so; so your reasoning isn't off that much. But I have Crowns doing the power thing and also I know a lot about hooking up systems. It sounds like you're still learning and so my advice would be to go the safe route and just get 8 ohms. If you want more later ..... then you can get a second set of speakers which will, when daisy chained, give you the higher power and having 4 speakers instead of two will give you a more noticable volume increase than using 2 4ohm speakers.

And twice the volume is only 3dB. I thought it was double the wattage for double the volume, or something(same as doubling the speakers, 2 speakers each outputting 100dB equates to 103dB), but doubling the volume is only 3dB which is the lowest change in volume we can hear. Something like that.

Yeah, I'm still learning. I've been to college etc, but they neglected to teach us anything about this. And as i said in another thread, I have live experience, it's just that it's mostly with actives, or a set already put together(out of my control).

I really wanna learn more.

Thanks for helping

Lee

[gbondo9]

Originally Posted by pandamonk

And twice the volume is only 3dB. I thought it was double the wattage for double the volume, or something(same as doubling the speakers, 2 speakers each outputting 100dB equates to 103dB), but doubling the volume is only 3dB which is the lowest change in volume we can hear. Something like that.

Yeah, I'm still learning. I've been to college etc, but they neglected to teach us anything about this. And as i said in another thread, I have live experience, it's just that it's mostly with actives, or a set already put together(out of my control).

I really wanna learn more.

Thanks for helping

Lee

hmmm.....

dB's are logarithmic...to the power of 10 and all that....and I was under the impression that every 10 decibels was double the volume. 24db is twice as loud as 12 db etc, etc. Somebody correct me on this if I'm wrong.....

I also *think* remember reading somewhere that a 6db increase is perceived as double volume - but that may be wrong and/or irrelevant as well.

3db is the decibel increase where your ears HEAR an increase. Less than that and the average ear doesn't notice a volume difference.

And double the power (wattage in this case I think) - should, in theory, double the volume (but obviously with amplifiers - circuitry and what not will probably play a huge role in actual volume output).

[Lt. Bob]

No ...... I believe 1 db is the smallest amount of change you ears can hear.
That's what they used to define what a decibel would be ... the smallest hearable change in volume would be 1 db. ..... so it's logritmic in that as it gets louder ..... it takes an increasingly greater change for your ears to detect. I think that's basically right though I could be mistaken.
However, while I'm not at all sure what decibel number equates to a doubling in volume, I am sure that doubling power does not double volume.
While the specifics will indeed vary depending on the amps, in general it takes 10 times the power to be twice as loud.
A 100 watt Marshall is not twice a loud as a 50 watter.

[pandamonk]

Originally Posted by Lt. Bob

No ...... I believe 1 db is the smallest amount of change you ears can hear.
That's what they used to define what a decibel would be ... the smallest hearable change in volume would be 1 db. ..... so it's logritmic in that as it gets louder ..... it takes an increasingly greater change for your ears to detect. I think that's basically right though I could be mistaken.
However, while I'm not at all sure what decibel number equates to a doubling in volume, I am sure that doubling power does not double volume.
While the specifics will indeed vary depending on the amps, in general it takes 10 times the power to be twice as loud.
A 100 watt Marshall is not twice a loud as a 50 watter.

With a doubling of wattage you see a 3dB increase. I think i got mixed up with power and volume. +3dB is twice the power(watts), and +6dB is twice the voltage. 10dB is a perceived doubling of volume. So a doubling of power gives roughly 30% more perceived volume. So if you have 2 100w speakers putting out 100dB, the volume will be 103dB(because it's a doubling of power, not a perceived doubling), the same as 1 200w speaker.

Ahh, it is right that 10xpower equals 10dB: 10xlog(1000/100)=10dB (double perceived volume).

[gbondo9]

OK - I think I got it now (sorry about some of the misinformation above).

I think this site clears up a lot of it (with examples): http://www.phys.unsw.edu.au/jw/dB.html

deciBel = 1/10th of a Bel (Bel = Created by Bell labs to quantify the reduction in audio level over a 1 mile length of standard telephone cable).

1 db change = Just Noticeable Difference between sound levels. It's not easy to hear the difference between 2 sounds that vary by 1db (check out the examples in the link above).

3 db change = Noticeable Difference between sound levels. I always heard that anything below this was not 'perceived' as a volume change by the average ear. Doing more reading though - I think this is subjective.

3db increase = roughly double power
6 dB increase = approximately four times the power and twice the voltage

10x power = double the volume

Half the power = reduce the volume by 3db

[pandamonk]

Originally Posted by gbondo9

OK - I think I got it now (sorry about some of the misinformation above).

I think this site clears up a lot of it (with examples): http://www.phys.unsw.edu.au/jw/dB.html

deciBel = 1/10th of a Bel (Bel = Created by Bell labs to quantify the reduction in audio level over a 1 mile length of standard telephone cable).

1 db change = Just Noticeable Difference between sound levels. It's not easy to hear the difference between 2 sounds that vary by 1db (check out the examples in the link above).

3 db change = Noticeable Difference between sound levels. I always heard that anything below this was not 'perceived' as a volume change by the average ear. Doing more reading though - I think this is subjective.

3db increase = roughly double power
6 dB increase = approximately four times the power and twice the voltage

10x power = double the volume

Half the power = reduce the volume by 3db

That's it .

Ok, so another question. Is it ok to run a low powered amp(100w) into a 500w rms speaker? Is there anything you should look out for?

[Lt. Bob]

sure ..... it's fine although some here will freak out about the possibility of frying a horn.
But really ...... just don't turn the amp wide open where the clip light is always on and you'll be fine.

[Mr. C]

Thanks Lt. Bob, I think you've pretty much cleared up my confusion. In fact in the manual it does say that with 8 ohms it puts out 165 watts (if I remember correctly). And it does say NOT to daisy chain two 4 ohms as it could damage the amplifier. So I guess I will look for some 8 ohms.

Now one more question. I see the speakers are rated xxx watts RMS and then yyy watts maximum. What does that mean? What wattage should I be looking for?

[pandamonk]

Originally Posted by Lt. Bob

sure ..... it's fine although some here will freak out about the possibility of frying a horn.
But really ...... just don't turn the amp wide open where the clip light is always on and you'll be fine.

Yeah thanks a bunch. You've been a lot of help.

What about using a full range speaker just as a sub? Asked this here(with more detail) also.

[Lt. Bob]

ummmmm, I usually look at RMS ratings for speakers ..... the max thing usually means that it'll take a peak of that much ..... but I, persoanally, don't pay any attention to that at all ...... only thing I'm interested in is the RMS capacity.

A full range for sub? .... hmmmmm, if it goes low enough and you have one so it saves you from having to buy one ...... why not?
Don't have time to check out the link though 'cause I'm headed to a gig ..... I'll get back to ya' this afternoon.

[Mr. C]

So what am I looking for in the RMS rating Bob? If it's rated 165 watts at 8 ohms am I looking for an RMS of at least a 165?

[pandamonk]

Originally Posted by Lt. Bob

ummmmm, I usually look at RMS ratings for speakers ..... the max thing usually means that it'll take a peak of that much ..... but I, persoanally, don't pay any attention to that at all ...... only thing I'm interested in is the RMS capacity.

A full range for sub? .... hmmmmm, if it goes low enough and you have one so it saves you from having to buy one ...... why not?
Don't have time to check out the link though 'cause I'm headed to a gig ..... I'll get back to ya' this afternoon.

The link just asks if it's ok to use full-range as a sub, and has a list of my equipment. The ones I'd use as subs have 15" drivers, and tops have 12".

Enjoy the gig.

[pandamonk]

Originally Posted by Mr. C

So what am I looking for in the RMS rating Bob? If it's rated 165 watts at 8 ohms am I looking for an RMS of at least a 165?

In my understanding, the amp should be slightly more than the RMS. So maybe look for 150w. Not sure though

[Simman]

Originally Posted by Mr. C

Thanks Lt. Bob, I think you've pretty much cleared up my confusion. In fact in the manual it does say that with 8 ohms it puts out 165 watts (if I remember correctly). And it does say NOT to daisy chain two 4 ohms as it could damage the amplifier. So I guess I will look for some 8 ohms.

Now one more question. I see the speakers are rated xxx watts RMS and then yyy watts maximum. What does that mean? What wattage should I be looking for?

RMS=0.707 x peak

This is the effective power (in this case) of a the amplifier.

When selecting speakers the effective power rating (RMS) should ideally match the RMS values of the amps they are connected to. However transients (peaks) will occur at higher levels and could potentially damage the speaker.

One other thing to consider is application. For example selecting a sub. Frequency responce of the speaker itself needs to be considered as well as power ratings. Since low frequenices will require more volume to sound at same level as say your mids, you generally need larger apms and/or run them bridged. In addition there are usually spikes (i.e. Kickdrum) that will generate considerable pressure on the speaker as well. Just some things to consider

[Lt. Bob]

I pretty much want speakers to handle as much as possible. I wouldn't choose a speaker because it has less handling capacity to try to make it match better to a lower powered PA.
If the amp'll put out 165 (is that a channel?) then I'd want speakers that's handle at least a couple of hundred and if the price was right I wouldn't care if the speakers could handle 2000 watts. Just makes it less likely you'll fry anything.
There's a lot of misconceptions about this ..... that bit about an amp needing more power than the ratings of the speakers is not correct.
The idea behind it is that an amp, if driven into clipping, puts out so much energy that it can damage speaker coils (almost always tweeters and horn drivers but rarely even a woofer). That is true and does happen.
But this doesn't happen because the speakers' rating was too high ..... it happens because the PA's power was too low ..... so you turn it up and up and up in a vain attempt to get it loud enough and you don't really get it louder past a certain point .... it just gets dirtier and dirtier and finally goes into hard clipping which is bad for voice coils.
But none of this would be avoided by having speakers that were rated less than the amp puts out .... if anything the speaker's more likely to burn because it can handle even less of the high energy clipping. The only way to avoid it is to recognise that "that's all it's gonna put out" and don't turn it up anymore.
So basically (even though someone might jump in and disagree ..... I've done PA's a LOT) I'm saying that you should not choose one speaker over another in order to have a speaker with a lower power rating. If that's the only difference ..... then always go for the speaker that'll take the most.