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General speaker questions for audio and home theater.

Some observations/comments

Howdy stranger! I assume at the start that your question "Why does the 70w/channel amp sound & measure much louder than the higher rated amp?" is based on retaining the balance of the system as a constant in the two listening experiences?

Firstly, the Watts to dBW conversion is accurate in electrical terms provided the input power rating is accurate to start with...

Amplifier manufacturers are guilty of, shall we just call it "loose interpretation", of the definitions of "output power" and "watts".

Similarly, speaker manufacturers can also sometimes quote misleading specs for their speakers - particularly that lovely term "nominal impedance" and also sensitivity.

The amplifier-related anomalies can be seen - using extremes - between the following "usages":

a) Continuous output power in Watts into an 8 ohm load, all channels driven, and measured across a frequency spectrum of 20Hz to 20KHz.

b) Peak Music Power Output (sic)

Now, a) is how power ratings SHOULD be quoted - by inclusion of parameters such as:

- a specified duration (in this example = "continuous")
- a specified speaker load (impedance in ohms)
- a specified number of active channels sharing the power supply
- a specified frequency range (in this case, the full audio spectrum)

On the other hand, b) omits all of these parameters and, as a result, it is virtually impossible to verify/disprove the claimed rating. Judging by some the numbers they come up with, I'd hazard a guess at some of the values to the parameters above as used for PMPO derivation:

- a specified duration = <1 millisecond (to save the power supply from exploding)
- a specified speaker load = somewhere between 2-4 ohms
- only a single channel active
- a specified frequency range = an interval of approximately 5Hz

Using these blatantly bullshit parameters allows these boombox manufacturers to quote PMPO outputs somewhere in the "Bevawatt" regions... :-)

Now, that comparison was based on hyperbole and looked at two extremes. Coming back to your question, I would check out the parameters mentioned above for each of the two amps - and using the first case example:

1) a specified duration (in this example = "continuous")
2) a specified range of speaker loads (impedance in ohms) (eg 8/4/2)
3) a specified number of active channels sharing the power supply
4) a specified frequency range (in this case, the full audio spectrum)

These parameters will provide a fairly good guide to the quality and reserves of the power supply(ies) used, while other information (if available) will help to assess the psycho-acoustic aspects (such as frequency-linked responses with peaks/troughs that might sound subjectively louder on one amp vs t'other), etc.

So, come back with the results of the comparison and research and then there might be enough information to answer the question. (You made no mention of brand/model references for the two amps).

I trust you are both well and have quaffed the first frothy of the day?
DevillEars


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