What does mean IHF dynamic power?


New member
Username: Panfis

Post Number: 5
Registered: Oct-05
Hello everybody. I have been searching for one integrated amplifier by Nad but when I read the specifications I don't understand very well them. For example the Nad C352 amp has the next datas:

Continuous output power 2x 80 watts
IHF dynamic power at 8 ohms 115 watts (20.61 dbw)

What of both datas is the real power of this amp and What does mean IHF?....I hope someone can help with this doubt. Thank you for the attention.


Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6257
Registered: May-04

I hate to say it but it means NAD doesn't want to tell you everything you should know about their products. IHF is an old technique for measuring output power; IHF standing for Institute of High Fidelity (http://www.soundstagemagazine.com/measurements/test_preamplifiers.htm). As you can see in the article link, there are also EIA specifications. All audio sold in the US has to meet FTC specifications. All of these measurement techniques try to present different ways to measure the performance of a piece of audio gear to get what they consider to be a representative picture of the unit's performance. There are lots of arguments about measurements but in general they are of minimal use in choosing any piece of audio equipment no matter what technique is used to get the numbers.

Put "IHF dynamic power" into a search engine to see how many references come up to anything other than NAD. The first 18 in my Yahoo engine were specifically for NAD products. Not many other companies promote this concept. And for good reason. Some do a pitiful job at dynamic (or peak) power and others feel the term is too vague to be of real use.

Dynamic power means what short term wattage can the amplifier produce when a dynamic peak in the signal comes along. It has no specific meaning to music regarding frequency response nor how long of duration the signal must be. It really only asks how much voltage swing is allowed in the power supply for instantaneous (peak) power. Every amplifer can produce wattage above its RMS (root mean squared) value for a short period of time. Just as every amplifier can work into a lower impedance load for a short time. The question that is not answered by the concept of dynamic power is how the amplifier accomplishes this feat and what happens immediately after the signal has past.

This is not to take anything away from the NAD products. Overall they do a very decent job compared to some of the drek that is sold as "hi fidelity". However, the dynamic power spec should, in my opinion, be viewed as a marketing tool rather than a performance measurement.


Silver Member
Username: Smitty

Post Number: 250
Registered: Dec-03
Presumably NAD uses this term to counter any negative impression one may get from their RMS ratings( eg. 50w x 5 for the T743 and 70w x 6 for the T753) which are typically lower than the mainstream competition but probably more accurate. H/K uses the term HCC(High Instantaneous Current Capacity) in their similary-rated receivers. Sherwood Newcastle uses the term 'Dynamic power (EIA Standard Rating)' in a similar manner.

As Jan so eloquently stated, I think what people typically are looking for is some measurement of a receiver to play music well at louder volumes.

For instance I'd like to see something that measured the following (eg. two 91dB sensitivity floorstanding speakers, seated 12 feet away, room size 10' x 14'):
a) How long can a receiver play 'party' music loud and clean? (eg. Pop/rock/R&B)
b) How well can a receiver handle significant swings from lows to peaks in music (eg. classical)?

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6690
Registered: May-04

The first is basically a constant, therefore: http://www.myhometheater.homestead.com/splcalculator.html

"a" and "b" will vary with each amplifier section.

I have always found it annoying that the audio industry has placed such an emphasis on wattage (without explaining how wattage is derived) when wattage alone means so little to either "a" or "b". After you've been around audio for awhile, you realize it is the sensitivity of the speaker, not the wattage of the amplifier, which will be the most important specification to look at. The fact that most loudspeakers operate at less than 5% efficiency is still an appalling idea. All this, of course, comes down to marketing and not what is good for the consumer.

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