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rms vs aes

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myser View Drop Down
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    Posted: 14 August 2010 at 6:07am
is the rms rating higher than the aes rating .. how does this work . so if a driver is rated at 800 aes what would i expect the rms to be .. ?  confused ..
myser
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Post Options Post Options   Thanks (0) Thanks(0)   Quote subbass Quote  Post ReplyReply Direct Link To This Post Posted: 14 August 2010 at 12:04pm
http://lmgtfy.com/?q=aes+power+rating

AES is same as RMS, but 3rd party verified

AES = RMS, but AES can be relied on 100% unlike RMS


Edited by subbass - 14 August 2010 at 12:06pm
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Post Options Post Options   Thanks (1) Thanks(1)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 14 August 2010 at 12:31pm
You really need a time to be specified on RMS.

Once the whole magnet and frame reach their maximum temperature the power rating goes way down.

AES is a very short duration test (under 2 hours IIRC). A 100 hour RMS rating (like the old JBL ones) will be much lower.
djk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote myser Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 7:16am
mmm .. conflicting answers 
myser
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cnc123 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cnc123 Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 6:32pm
In short
As a general estimate or a gest-ermate the “rms” is a third less of the “aes”
quote myser “so if a driver is rated at 800 aes what would i expect the rms to be” = 600w rms approx

before the 80s  speak power ratings where for use with valve amps generally of small power
so you had British and American watts rms with no standard test procedure

British ratings where “Continuous rms” (sinewave at min impedance typically 400Hz)
or “Nominal rms”
(normal watts, What normal?. dictionary explanation. existing in name only)
Like old Goodman speak for example
Amercan ratings  at 1kHz rms and later on a aes test for 8 hours all gave higher numbers
Djk the man to ask especially on the history of American ratings
and all the other rating example
IEA
DIN
IEEE
IEC
FTC
ANSI
and more.
dont ask question with answers. thats negative but with
why why why untill you get and understand the answers you want
P.s workt  especially well when I was under 10


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sibulus Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2010 at 9:32pm
http://www.doctorproaudio.com/doctor/temas/powerhandling.htm


a good read. OP, are you a Buddist by any chance?

http://soundcloud.com/judas-beast
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _djk_ Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 3:20am
That last reference at

http://www.doctorproaudio.com/doctor/temas/powerhandling.htm

Is quite good until the end of part 4 (causes of speaker failure),
  • too much input power
Should be changed to: too much long term average power.
  • signals outside the speaker bandpass (radio frequency, subsonic frequencies, deep bass). Energy not to converted to sound ends up as heat
Should be changed to: too much power outside of the speaker's bandpass causes mechanical damage, or thermal damage from RF or oscillation.
  • amplifier clip, the most common cause of thermal failure
Amplifier clipping causes no damage what so ever, unless you exceed the long term average power limit of the driver, or it causes mechanical damage. (more on this later).
  • direct current (DC) at the amplifier output, although this is uncommon in today's amplifiers
This is partially true, and if your amplifiers don't have DC protection, you need to build a crowbar protection circuit, and use HF protection caps as appropriate.
  • excessive equalization, mostly high frequencies, since these frequencies exhibit low transducer efficiency and generate lots of heat
That comes back to excessive long term average power, and not having enough drivers to handle it.

and part 5 (selecting amplifier power).

In general, the amplifier power needs to be larger than the speaker's rated power. This is because an amplifier only delivers its rated output power with sinewave signal, and delivers much less with a real signal with dynamics.

Totally backwards. Every amplifier puts out WAY more than its rated RMS power on program material. The only possible exception to this would be an amplifier with foldback current limiting trying to drive  a very reactive loudspeaker into its rated minimum load. Four 8 ohm woofers in parallel are an example of this, unless the amplifier is expressly designed to do so (an example of this would be the QSC RMX 1850HD. An 1850HD is a 2450 with a reduced voltage, increased amperage transformer. In spite of its reduced power output at 2R, 900W vs 1200W, it still only carries an EIA rating at 2R, and not an FTC rating like it does at 8R and 4R).

The Crown VZ series are another example of the above,
when driving four 8 ohm woofers in parallel the ODEP lights will occasionally flash (even if not clipping). When this occurs the amplifier cuts its power supply voltage in half (in theory reducing power by a factor of four). Yes, a VZ will drive even a 1R load, but it will lock itself down into low voltage mode (to protect itself). It will also lock down to low voltage mode if it gets too hot for a long period of time.

An Altec 9440 was an old favorite of mine, it too would lock down to a lower supply voltage if you got it too hot driving a low impedance. It also had a thermal shut-off if things got out of hand (fan failure or similar).


will continue later
 As ageneral guideline, it is recommended to use an amplifier delivering 50% more power than the speaker's average ("RMS") power. For example, for a speaker with 450W average power, an amplifier with an output of 700W may be used. If a small amplifier is used, sufficient level will not be reached, nor the perception that it is attained, so the signal will tend to be clipped to compensate, thus endangering the integrity of the speaker.

The cabinet design also affects thermal power ratings too. It's all about getting rid of the heat, a tightly sealed rear chamber can't get rid of the heat (without some external heat exchanger).
djk
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cnc123 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cnc123 Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 3:34am
arr grasshopper not gras-shoppper you guess

http://www.youtube.com/watch?v=WCyJRXvPNRo&feature=related



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Post Options Post Options   Thanks (0) Thanks(0)   Quote cnc123 Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 5:44am
arrr djk enlighten us some more  to be continued later you said
I shall have patience till then

the fat Buddha
p.s nice one about the amps
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass traffic Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2010 at 6:03am
Good reading this thread, hopefully I'll remember to keep checking it!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote myser Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 6:31am
cheers for info guys...  
yep am Buddhist ...
Chinese proverb say - " he who goes to bed with itchy bum awaken with smelly finger  "

myser
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myser View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote myser Quote  Post ReplyReply Direct Link To This Post Posted: 17 August 2010 at 5:59pm
what about "nominal power handling " as a power rating  ... ?
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