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Author Topic: New Generation "High Powered" MI Level Speakers  (Read 11058 times)

DBA

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New Generation "High Powered" MI Level Speakers
« on: February 04, 2011, 03:39:23 pm »

Looking at the specs for new(ish) generation top tier MI loudspeakers (take Peavey QW or SRX for example)  I can't help but think some of the power handling figures are marketing fluff.   

For Example:
JBL SRX 715 is rated Passive: 800 RMS/1600 Program/ 3200 Peak
Peavey QW2: 1600 watts program, 3200 watts peak
 
So,  now that we have an apples to apples loudspeaker comparison that have similar output,  sensitivity, frequency response, etc..etc and technically should be a close drag race between them.

Does this mean for either of these two cabinients, the LARGEST PLX amp (let's just agree for a moment that this amp line is suficient to match most MI level use..because it is) is "ONLY" good for 700watts RMS at full tilt on either of these speakers wich is barely,  if not even, their RMS power levels?

Ok,  so now to the real world.   What does this really mean?   Does it mean that neither of these loudspeakers can be pushed to acceptable levels for a rock band or DJ use with one of the biggest MI level amps you can buy?   Or does it mean,  they will get loud enough without catching on fire?   Does it really mean that a DJ could take a PLX 3402 and let it rip on either of these cabinents constantly in "clip" or "peak" and never burn up anything?   I mean, that's what the RMS figures suggest right?   I just find it all hard to believe, or maybe I have been out  of it for too long. 

Is there really that much to be gained by hitting these speakers with a solid 1600 watts each?   If manufactures are making simply trying to make bulletproof speakers, I am for that.  If they are truely making speakers to hold this much power to get slightly louder, then I don't really see the point in having to have 6,000 watts on tap to power a pair of them.   

This question is just a general observation to some of the huge power figures on speakers these days.   

Maybe, I should have just asked "What do you power your SRX and similar high powered cabs with and how do they sound".       
« Last Edit: February 04, 2011, 03:53:30 pm by Whit Hutchinson »
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Steve Ferreira

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Re: New Generation "High Powered" MI Level Speakers
« Reply #1 on: February 04, 2011, 05:16:07 pm »

This past weekend I powered 2x712s with an Itech 8000. I didn't use all that power, but they sure did get up and go. I also use the rms limiters in the ITechs just to make sure nothing blows up.
Any of the speakers you mentioned will take that kind of power and sound good. By matching the rms with an amp will not give you enough headroom for transients to "get through". You don't want to clip an amp into any speaker.

As for your last question:I power up srx 725s and 728 with IT8000s. That's a 1200 watts rms @4 ohms cab on a 4000 watts per ch amp.
« Last Edit: February 04, 2011, 05:17:54 pm by Steve Ferreira »
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Tracy Garner

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Re: New Generation "High Powered" MI Level Speakers
« Reply #2 on: February 04, 2011, 06:30:01 pm »

My main go to rig is 2x IT8000 with 4x 725/728. It runs at 2 ohms on 2 20amp circuits (sometimes even 1-20 amp circuit with control). If I do only 1 bottom/top per side, I don't change any amp settings. Sometimes, I hook straight up into a DJ mixer and other times I will use up to a 40 channel console for bands/choirs. I'm enjoying a pretty versatile setup I can move myself except for the occasional endless staircase. Even then, I usually enlist a security guy instead of the second helper. When I do need a helper in these cases, its more about needing production help than moving help.

I'm really not a big fan of the sound of a 725 overall but for the weight and power, and even reliability, its hard to beat.

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Paul G. OBrien

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Re: New Generation "High Powered" MI Level Speakers
« Reply #3 on: February 04, 2011, 11:41:48 pm »

Looking at the specs for new(ish) generation top tier MI loudspeakers (take Peavey QW or SRX for example)  I can't help but think some of the power handling figures are marketing fluff.   

For Example:
JBL SRX 715 is rated Passive: 800 RMS/1600 Program/ 3200 Peak
Peavey QW2: 1600 watts program, 3200 watts peak

Ok,  so now to the real world.   What does this really mean?

It means the manufacturers tested these speakers with an 800w signal that had momentary peaks(maybe only miliseconds) of up to 3200w.. and they survived. That may sound like a lot but you have to remember these 3 numbers represent the last 6db of power handling where most of the power compression and distortion occurs, or where the output gains from adding more power are dimishing fast.

Does it mean that neither of these loudspeakers can be pushed to acceptable levels for a rock band or DJ use with one of the biggest MI level amps you can buy?
Not unless you consider close to 130db output from a pair of speakers unacceptable, because that is what they will produce with about 700w each

Does it really mean that a DJ could take a PLX 3402 and let it rip on either of these cabinents constantly in "clip" or "peak" and never burn up anything?
Absolutely not, but it's because of what happens to an amp pushed deep into clipping, it produces a squashed(compressed) signal with heavy high freq distortion content that will be at quite a bit higher output level than what the amp is spec'd to produce, and that is something speaker systems in general aren't designed to handle.

Is there really that much to be gained by hitting these speakers with a solid 1600 watts each? 
Yes.. as some of the other responders have already indicated, but it depends upon the source material and what you do with that 1600w. It should be used as headroom to cover momentary peaks without clipping the amp, you cannot push sine waves at this power level.. for that you have to keep it at the RMS rating.
« Last Edit: February 04, 2011, 11:45:22 pm by Paul G. OBrien »
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Bob Leonard

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Re: New Generation "High Powered" MI Level Speakers
« Reply #4 on: February 05, 2011, 01:53:05 am »

The question of amplifier rating has been discussed many times in the past and I have yet to see anyone come up with a better rule of thumb than the rule of thumb which has been used for the past 40 or so years.
 
If you want your speakers to perform to their potential then;
 
Take the RMS long term capability of the cabinet and multiply it by two. In the case of you SRX example, which is not considered an MI or entry level cabinet your amplifer should provide.
 
2 x 800 watts = 1600 watts. 1.5 can be substituted for 2, and an amplifer which provides 800 watts may work fine depending on the application and as long as the amplifier does not clip.
 
In most cases it is usually long term clipping caused when under powering the cabinet which destroys the drivers, not the instantaneous peaks the cabinets are designed to handle at 1600 or 3200 watts when using a properly sized amplifier that does not clip.
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Brad Weber

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Re: New Generation "High Powered" MI Level Speakers
« Reply #5 on: February 05, 2011, 08:46:39 am »

I agree with Paul's response, it all depends on what you are trying to do.  Having an amp rated equal to or even less than the RMS rating of the speaker may be absolutely fine and provide plenty of headroom unless you try to get more out of that combination than it can support.  There is no magic that happens by using an amp rated at 1.5 to 2 times the continuous power rating of the speaker, that is simply a general guideline to have a reasonable balance of maximum output and reliability.  Maybe the simplest way to put it is that it is the use that defines what power is needed or appropriate and a speaker power rating does not define what power a speaker needs but rather what power it can handle.

There are two aspects of speaker power ratings that are commonly overlooked.  One is that typically only the continuous power rating of a speaker is actually measured.  The peak rating is assumed calculated based on that measurement and the crest factor of the test signal while the Program rating is just a number somewhere between those two, typically midway between them.  The other aspect is that nothing says the speaker performance stays the same all the way up to the ratings, there could be variations in frequency response or other changes prior to there being some form of failure.  This is one reason why people sometimes may subjectively feel that a certain speaker sounds better with more power, but it also is not inherently a positive nor is it reflected in specifications.

People sometimes seem to get too caught up in power values that probably don't matter as much as they think.  For example, being worried that the Program rating of the speaker is 1,200W and you only have a 1,000W to power it, a 0.8dB difference that probably no one would notice.

To the comment "Does it really mean that a DJ could take a PLX 3402 and let it rip on either of these cabinents constantly in "clip" or "peak" and never burn up anything?   I mean, that's what the RMS figures suggest right?", the short answer is no, that is not what it means.  The long term or continuous (not RMS, there is no such things as RMS Watts) rating is simply the power the speaker could handle for a specific period of time with a specific test signal.  Clipping is not part of the rating.
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Ivan Beaver

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Re: New Generation "High Powered" MI Level Speakers
« Reply #6 on: February 05, 2011, 11:13:14 am »

ALso in relation to what Brad said (which is right on as usual) is looking at the peak SPL outputs that are often listed.

There are all kinds of different ways to come up with the published numbers.  Is that peak SPL a sinlge freq that the rest of the response cannot equal?  I know of one manfacturer that lists their active products as having a much higher output than their passive models.

WHY?  Because in the active measurements there are no eq filters and there is a HUGE (think 10-15dB) peak at one freq that makes the "peak" SPL really look large.  But nobody wants to actually listen to a loudspeaker that has a peak in the response that large.  But are they lying-no-the loudspeaker will do it-but it is VERY misleading because the typical user will take that single number (without looking at a response chart) and compare it to other products who do not have that peak and wrongly mistake it as being a louder box.

Is it a calculated value from the measured freq response?  If so-where in the freq response?  Is it a usable average from a line drawn down the average of the response?  Or a peak in the response-which could be several dB higher than the average?

If you are going to get pickly about a couple of dB, then you REALLY have to look and know where  those numbers are coming from
STUPID FORUM  WHY DO IT IT KEEP JUMPING AROUND WHEN YOU TYPE ONCE YOU GET PAST A CERTAIN POINT

DOES ANYBODY ELSE HAVE THIS PROBLEM?

IT ONLY HAPPENS ON THIS FORUM

REALLY REALLY ANNOYING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Brad Weber

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Re: New Generation "High Powered" MI Level Speakers
« Reply #7 on: February 05, 2011, 12:40:23 pm »

STUPID FORUM  WHY DO IT IT KEEP JUMPING AROUND WHEN YOU TYPE ONCE YOU GET PAST A CERTAIN POINT

DOES ANYBODY ELSE HAVE THIS PROBLEM?

IT ONLY HAPPENS ON THIS FORUM

REALLY REALLY ANNOYING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Ivan, mouse over the two little horizontal lines in the center just below the bottom of the reply window, that should allow you to resize the window to avoid the problem.
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Douglas R. Allen

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Re: New Generation "High Powered" MI Level Speakers
« Reply #8 on: February 06, 2011, 06:37:20 am »

Whit.
What is important and often over looked as well is how loud a given speaker gets with the wattage put in.
A speaker that handles 1000 watts rms and only puts out 105dbs is not really that good of a speaker.......

Instead of going for the most power and highest power handling speaker one should work in reverse.

How loud do you need it to be at a location?

Purchase enough amps and speakers to be at that spl level with some headroom to spare. In live sound I try for at least 10dbs although it doesn't always happen.

Buying a system that needs to be run at peak levels at all times should be avoided. Even if the system is not loud enough with the amps just starting to clip turning it down 3/6 dbs is not going to make or break a show. I can't remember the last time someone has come up to me and say " Could you please turn this F"%!ing thing up!" Just being loud does not make a good show. Allot of times its just so much noise.

Don't play the "How loud can I get" game.
Instead go for "How good can I make this sound"

Douglas R. Allen
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john manson

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Re: New Generation "High Powered" MI Level Speakers
« Reply #9 on: February 06, 2011, 07:39:51 pm »

What does "MI" stand for?
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Reggie Kendrick

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Re: New Generation "High Powered" MI Level Speakers
« Reply #10 on: February 06, 2011, 08:06:32 pm »

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Bob Leonard

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Re: New Generation "High Powered" MI Level Speakers
« Reply #11 on: February 07, 2011, 03:20:01 am »

I agree with Paul's response, it all depends on what you are trying to do.  Having an amp rated equal to or even less than the RMS rating of the speaker may be absolutely fine and provide plenty of headroom unless you try to get more out of that combination than it can support.  There is no magic that happens by using an amp rated at 1.5 to 2 times the continuous power rating of the speaker, that is simply a general guideline to have a reasonable balance of maximum output and reliability.  Maybe the simplest way to put it is that it is the use that defines what power is needed or appropriate and a speaker power rating does not define what power a speaker needs but rather what power it can handle.

There are two aspects of speaker power ratings that are commonly overlooked.  One is that typically only the continuous power rating of a speaker is actually measured.  The peak rating is assumed calculated based on that measurement and the crest factor of the test signal while the Program rating is just a number somewhere between those two, typically midway between them.  The other aspect is that nothing says the speaker performance stays the same all the way up to the ratings, there could be variations in frequency response or other changes prior to there being some form of failure.  This is one reason why people sometimes may subjectively feel that a certain speaker sounds better with more power, but it also is not inherently a positive nor is it reflected in specifications.

People sometimes seem to get too caught up in power values that probably don't matter as much as they think.  For example, being worried that the Program rating of the speaker is 1,200W and you only have a 1,000W to power it, a 0.8dB difference that probably no one would notice.

To the comment "Does it really mean that a DJ could take a PLX 3402 and let it rip on either of these cabinents constantly in "clip" or "peak" and never burn up anything?   I mean, that's what the RMS figures suggest right?", the short answer is no, that is not what it means.  The long term or continuous (not RMS, there is no such things as RMS Watts) rating is simply the power the speaker could handle for a specific period of time with a specific test signal.  Clipping is not part of the rating.

Not sure if you may have missed this part of my statement.
 
"2 x 800 watts = 1600 watts. 1.5 can be substituted for 2, and an amplifer which provides 800 watts may work fine depending on the application and as long as the amplifier does not clip."

Clipping, when an amplifier will reach at least twice it's rated output power, is a very real and common reason for driver failure, usually the compression drivers first.
 
You are correct in stateing that the term RMS when used today is innacurate. An RMS rating would depend on a purely resistive load and speakers of any type are not a purely resistive load. I'll amend my old school statement to read "manufacturers long term power rating".
 
In a general context without measurement and analysis of the application I'll stand by my time proven rule of thumb and add that for the novice this rule is in most cases the safest method to use for sizing an amplifier.
 
I'll state that because regardless of the amplifier size, a person who fails to recognize the limits of their speakers and system can and will destroy drivers regardless of amplifier size, and will destroy those drivers more often with an amplifier rated much lower than most manufacturers recommend. And that manufacturers recommendation will almost always be 2x the long term power rating. I have rarely met the person looking for less power for their cabinets, at least not in my 45 years of working with sound.
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John Roberts {JR}

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Re: New Generation "High Powered" MI Level Speakers
« Reply #12 on: February 07, 2011, 10:23:45 am »


Not sure if you may have missed this part of my statement.
 
"2 x 800 watts = 1600 watts. 1.5 can be substituted for 2, and an amplifer which provides 800 watts may work fine depending on the application and as long as the amplifier does not clip."

Clipping, when an amplifier will reach at least twice it's rated output power, is a very real and common reason for driver failure, usually the compression drivers first.
 
You are correct in stateing that the term RMS when used today is innacurate. An RMS rating would depend on a purely resistive load and speakers of any type are not a purely resistive load. I'll amend my old school statement to read "manufacturers long term power rating".
 
In a general context without measurement and analysis of the application I'll stand by my time proven rule of thumb and add that for the novice this rule is in most cases the safest method to use for sizing an amplifier.
 
I'll state that because regardless of the amplifier size, a person who fails to recognize the limits of their speakers and system can and will destroy drivers regardless of amplifier size, and will destroy those drivers more often with an amplifier rated much lower than most manufacturers recommend. And that manufacturers recommendation will almost always be 2x the long term power rating. I have rarely met the person looking for less power for their cabinets, at least not in my 45 years of working with sound.

This is the first time we had this discussion since re-skinning this forum.

It is true that an amplifier clipped so hard it turns a sine wave into a square wave will put out roughly 2x it's clean sine wave power. IMO more important is the simpler explanation. Amplifiers clip because the operator turns up the gain too high. This "too high" gain increases all of the signal, not just the peaks that may be clipped. It is this higher average power that overheats the voice coil.

This topic has been beat to death, but not completely to death.

Sizing power amps to loudspeakers is not neat. To get useful peak output we routinely connect them to amplifiers that can fry them long term. The operator must use some discretion.

This is a little like car engines. To be able to get up to cruising speed quickly and safely we put in bigger motors than we need to just barely reach speed limits. That's why we have speedometers and temperature gauges. A stock passenger car driven at full throttle for too long, like on a race track, could overheat and fail. Just like a loudspeaker driven too hard. 

JR
 
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Geoff Doane

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Re: New Generation "High Powered" MI Level Speakers
« Reply #13 on: February 07, 2011, 10:49:55 am »

 
You are correct in stateing that the term RMS when used today is innacurate. An RMS rating would depend on a purely resistive load and speakers of any type are not a purely resistive load. I'll amend my old school statement to read "manufacturers long term power rating".
 

At the risk of being pedantic, I think Brad was correct when he said "There is no such thing as RMS watts".  I remember an instructor telling us the same thing in tech school, 30-odd years ago.  The term has been appropriated by marketers to mean "continuous average sine wave power", or something like that, although I do admit that "RMS" does roll off the tongue more easily.

All the rest of that stuff, I'm in agreement with.  People would blow up fewer speakers if they listened to the speakers, could recognize the sound of speakers reaching their limits, and actually cared about not blowing them up. ::)

GTD
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Bennett Prescott

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Re: New Generation "High Powered" MI Level Speakers
« Reply #14 on: February 07, 2011, 10:58:04 am »

Here is an article I wrote on this very subject. The rules of thumb from 20 years ago still apply, but you can extract much more performance from a loudspeaker by using RMS limiting, which is now widely available.

http://www.bennettprescott.com/downloads/LoudspeakerFundamentals.pdf
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Brad Weber

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Re: New Generation "High Powered" MI Level Speakers
« Reply #15 on: February 08, 2011, 08:00:17 am »


Not sure if you may have missed this part of my statement.
 
"2 x 800 watts = 1600 watts. 1.5 can be substituted for 2, and an amplifer which provides 800 watts may work fine depending on the application and as long as the amplifier does not clip."
Not missed, just being reinforced.

I'll state that because regardless of the amplifier size, a person who fails to recognize the limits of their speakers and system can and will destroy drivers regardless of amplifier size, and will destroy those drivers more often with an amplifier rated much lower than most manufacturers recommend. And that manufacturers recommendation will almost always be 2x the long term power rating. I have rarely met the person looking for less power for their cabinets, at least not in my 45 years of working with sound.
The context of the 1.5 to 2 times the continuous rating of the speakers 'rule of thumb' is essentially having a reasonable balance of getting as loud as possible with reliability and for many situations that is indeed the goal.  However, in some situations it may not be the only consideration or even a consideration at all and I have seen where the budget or the requirements of the application led to lower power amplifiers being used with totally acceptable results.

In the install world it is common practice to start with determining the desired levels in the audience, add some desired headroom (typically 10-20dB), back that into a required level at 1m and then use the speaker sensitivity to determine the power required.  In that approach the speaker power rating is simply a verification that the speaker can handle the power required and not a factor in determining the amplifier power required.
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DBA

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Re: New Generation "High Powered" MI Level Speakers
« Reply #16 on: February 08, 2011, 09:49:59 am »

Thanks for the replies.

I guess I should have just asked my question as:

Is it really necessary to power these newer speakers at their program levels to get adequate performance from them, or will they still get loud enough at RMS levels for 90% of applications?

I know as you start to push things close to the limits of power handling the performance vs. input wattage falls off quickly.     I was just curious as to if this means that they can still get as loud as they ever have been able to,   but they are more resistent to letting the smoke out. 

Clearly they dont expect everyone to buy a fricken Itech 6k or 8k to run these things. 
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Brad Weber

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Re: New Generation "High Powered" MI Level Speakers
« Reply #17 on: February 08, 2011, 12:12:04 pm »

I guess I should have just asked my question as:

Is it really necessary to power these newer speakers at their program levels to get adequate performance from them, or will they still get loud enough at RMS levels for 90% of applications?
3dB.  That could be 3dB of additional output level with the same headroom or 3dB of additional headroom with the same output level but either way, that's the difference between using an amp rated a the continuous rating of the speaker and one rated at the program rating.  A 3dB increase in level is going to be noticeable and would normally be perceived as somewhere around a 23% increase in loudness or 1.23 times as loud.
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Re: New Generation "High Powered" MI Level Speakers
« Reply #17 on: February 08, 2011, 12:12:04 pm »


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