ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: New Generation "High Powered" MI Level Speakers  (Read 10746 times)

Reggie Kendrick

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 82
  • Channel Live Productions - raising the bar...
    • Channel Live Productions
Re: New Generation "High Powered" MI Level Speakers
« Reply #10 on: February 06, 2011, 08:06:32 pm »

Logged
Raising the bar...

Atlanta Wedding DJs
Atlanta DJs / Wedding DJs / Prom DJs ...and more

Bob Leonard

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6807
  • Boston, MA USA
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.
Logged
BOSTON STRONG........
Proud Vietnam Veteran

I did a gig for Otis Elevator once. Like every job, it had it's ups and downs.

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16338
  • Hickory, Mississippi, USA
    • Resotune
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
 
Logged
Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Geoff Doane

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 815
  • Halifax, NS
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
Logged

Bennett Prescott

  • Full Member
  • ***
  • Offline Offline
  • Posts: 138
  • This text is personal!
    • Bennett Prescott Dot Com
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
Logged
-- Bennett Prescott
Director of North American Sales
ADRaudio d.o.o.
Cell: (518) 488-7190

"Give me 6dB and I shall move the world." -Archimedes

Brad Weber

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2209
  • Marietta, GA
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.
Logged

DBA

  • Newbie
  • *
  • Offline Offline
  • Posts: 24
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. 
Logged

Brad Weber

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2209
  • Marietta, GA
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.
Logged
Pages: 1 [2]  All   Go Up
 


Page created in 0.06 seconds with 21 queries.