Kamis, 20 Maret 2014

Do Not Be Deceived By The Manufacturer Ratings Of Today's Power Amps

By Marta McBrian


Audio amp providers generally present the frequency response of their products and solutions that, unfortunately, does not always show you a lot concerning the audio quality. I am going to shed light on the meaning of this expression and additionally offer some recommendations on how to interpret it when searching for an amplifier. An amplifier is only able to function within a particular frequency range. Any signals outside of this range are going to be removed. As such the frequency response gives a significant hint concerning if a particular amplifier could be well suited for a specific use. Usually a lower and upper frequency are provided, just like 20 Hz - 20 kHz. This kind of spec shows that the amp will be able to amplify music inside of this frequency range. You could be tempted to decide on an amp that offers the biggest frequency response. However, there is certainly more to comprehending an amplifier's overall performance than just understanding this simple range.

An amplifier is made to amplify a sound signal enough in order to drive a couple of loudspeakers to moderate or higher volume. Suppliers typically publish the frequency range over which the amplifier works. Normally a lower and upper frequency are provided, like 20 Hz - 20 kHz. This spec suggests that the amp has the capacity to amplify music within this frequency range. You could be tempted to go with an amp that gives the biggest frequency response. Then again, there's far more to comprehending an amplifier's functionality than only realizing this simple range. A large frequency response doesn't mean the amplifier has good sound quality. For example an amplifier having a frequency response between 30 Hz and 15 kHz might sound a lot better than a different amplifier having a response between 10 Hz and 30 kHz. Also, each supplier, it seems, uses a different procedure for specifying the lowest and maximum frequency of their amplifiers. Typically, the frequency response shows the standard operating range of the amp. Inside this range, the amp gain is essentially constant. At the lower and upper cutoff frequencies the gain is going to decrease by no more than 3 decibels.

On the other hand, several manufacturers push this standard to the limit and may list a maximum frequency where the amp is going to barely generate a signal any longer. In addition, simply looking at these 2 numbers won't say a lot about the linearity of the frequency response. Therefore it is ideal to have a complete frequency response chart. This sort of graph is going to reveal whether or not there are any significant peaks or valleys inside the working frequency range. You may also desire to ask for a phase response diagram which also presents crucial hints about the sound quality.

In order to better understand the frequency response behavior of a particular type, you should try to figure out under which conditions the response was calculated. You will probably find this info in the data sheet of the amplifier. However, most manufacturers won't show those in which case you may need to contact the producer directly. One condition which can impact the frequency response is the impedance of the loudspeaker attached to the amplifier. Standard speaker impedances range from 2 to 16 Ohms. The lower the loudspeaker impedance the higher the strain for the amplifier.

Primarily contemporary digital or "Class-D" amps will show changes in the frequency response with different loads. The primary reason is the fact that Class-D amps use switching FETs as the power phase which produce quite a lot of switching components. These components are removed with a filter which is part of the amp. A varying loudspeaker load will affect the filter response to some extent. Normally the lower the loudspeaker impedance the lower the highest frequency of the amp. Furthermore, the linearity of the amplifier gain is going to depend on the load. Some amps incorporate feedback as a way to compensate for changes in gain due to different connected loads. Other amps employ transformers and provide outputs for different speaker loads. Aside from improving the frequency response of the amplifier, this method normally additionally enhances the amplifier efficiency.




About the Author:



Tidak ada komentar:

Posting Komentar