RMS vs Dynamic Power handling? Does the "dynamic" power mean anything? [Archive] - Audio & Video Forums

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riotact
12-25-2009, 11:19 AM
Hey all, I am looking at a Klipsch KSW-10 Sub. It says the RMS is only 50 watts, but the dynamic is 225. Is dynamic just another word for peak, aka not really how much power it will put out?

I guess im just wondering how much power this thing will have?

KSW-10 Specifications:

* Frequency response: 29Hz-120Hz±3dB
* Power handling:
FTC Rated Power: 55 watts continuous, 22-125Hz @ = 1% THD
Dynamic Power*: 225 watts @ = 1% THD *Dynamic power indicates the actual power this amplifier will deliver to the woofer under normal operating conditions. While the FTC power rating indicates power available on a continuous, long-term basis, subwoofers do not rely on that type of power. Instead, the amplifier is called upon to deliver large, short-term peaks of power to be able to support the wide dynamics required by today's digital music and movie formats. In addition to the required FTC power rating, we've provided the dynamic power rating as a better indication of the product's true performance.
* Sensitivity: 110dB SPL 1/8 space, 1 meter
* Low pass crossover: Continuously variable from 40-120Hz, 24dB/octave slope above 120Hz
* Woofer: K-1070-K 10" (25.4cm) down-firing fiber-composite cone
* Amplifier: Class A/B discrete MOSFET outputs
* Phase: Switchable 0 or 180 degrees
* Enclosure material: MDF
* Enclosure type: Bass reflex via rear-mounted port
* Inputs: 2) Line level/LFE RCA phono jacks and 2) High level speaker terminals
* Auto power on: 2 Second ON delay, 15 minute OFF delay
* Dimensions: 15.5" (39.37cm) x 13.5" (34.3cm) x 13.5" (34.3cm)
* Weight: 29 lbs. (13.18kg)
* Finishes: Matte-finish Black vinyl
* Voltage: 110/120 VAC/60Hz
* Export voltage: 230 VAC 50/60Hz
* Built from 1998

http://www.wwstereo.com/website/ecommerce/productdetail.aspx?product=KSW-10

harley .guy07
12-25-2009, 03:34 PM
Well yes it does. RMS power stands for Rate Mean Square. Which is a measure of constant output power over a 1 minute interval. Peak power is a rating of power of a 1 millisecond burst of signal and it is the highest power that the amp can put out without square waving in 1 millisecond. Peak power is more useful of a measurement for high volume musical peaks and RMS is a more real world measurement meant to be what to expect from the amp in normal circumstances with normal volume loads. Dynamic power output and peak power output are used by different companies but mean the same thing in almost all cases. The only other measurement that most companies publish without going through the owners manual or pdf is the Dynamic Headroom which basically the difference between the RMS power and the Peak power output of an amplifier. It is kind or hard to believe that the 55 watt amp in this sub has a peak power of 225 watts, but is not unheard of I suppose. that just means that the amp is a more dynamic peak oriented amplifier than a continuous power output amp which for a sub meant for movie peaks it would not seem as different for a company to do such a thing.

canuckle
01-01-2010, 02:23 AM
Not to be nitpicky, but...


RMS power stands for Rate Mean Square.
Fail. RMS stands for root mean square. As in: the square root of the mean of the squares of the values.


Which is a measure of constant output power over a 1 minute interval.
Fail. It's just an average that in electronics is used to express the power magnitude that can be continuously output by a device... 1 minute, 1 hour, 1 year, 1 decade... there is no time period associated with rms power ratings. It's a sad amp that could only output at its rms rating for 1 minute.


Peak power is a rating of power of a 1 millisecond burst of signal and it is the highest power that the amp can put out without square waving in 1 millisecond
Fail. Again, there is no proscribed period that the power is measured in, it's just a rating of the power that the unit is capable of. If peak power were only achievable for 1 millisecond, it would be a pretty useless rating and the amp would have pretty sad capacitors.

Ajani
01-01-2010, 06:28 AM
Not to be nitpicky, but...


Fail. RMS stands for root mean square. As in: the square root of the mean of the squares of the values.


Fail. It's just an average that in electronics is used to express the power magnitude that can be continuously output by a device... 1 minute, 1 hour, 1 year, 1 decade... there is no time period associated with rms power ratings. It's a sad amp that could only output at its rms rating for 1 minute.


Fail. Again, there is no proscribed period that the power is measured in, it's just a rating of the power that the unit is capable of. If peak power were only achievable for 1 millisecond, it would be a pretty useless rating and the amp would have pretty sad capacitors.

Been watching a lot of 'failblog' clips on youtube?

mlsstl
01-01-2010, 09:28 AM
There is no standard industry definition for "dynamic" power. It means whatever the manufacturer wants it to mean. I discount all such references as marketing jargon of the useless variety.

If you think about it, if any part of the audio spectrum needs "continuous" power, it is in the bass region. I was at church the other day listening to their pipe organ. That beast (about 7,700 pipes - it's in an old cathedral) is capable of putting out some very sustained deep bass frequencies. If that's the music you're trying to reproduce with this sub and 50 watts isn't enough, then their "dynamic" rating is of no help whatsoever.

That said, the subwoofer's 50 watts may well be perfectly adequate depending on the volume level you're trying to achieve. The dynamic rating of 225 watts may only be present for impressing the susceptible. I'd recommend listening to the unit and see if it does what you want done.

harley .guy07
01-01-2010, 12:16 PM
I was talking about what most companies test with and damn if someone has to role all over it. I will watch my typing from now on and also let the coolio's of this forum answer all the damn questions since they know so much. I guess you need to write a book or something because you have tried to fail me several times and I was going off of how a lot of companies test there power output used pink noise. I guess I will let you answer all the tough questions from now on there trigger.