Home Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

[ Follow Ups ] Thread: [ Display  All  Email ] [ Propeller Head Plaza ]
[ Alert Moderator ]

100% correct

My recent experiments with a speaker requiring substantial bass boost to equalize its output making the deepest bass it is capable of flat has convinced me that clipping is a horrible sound. The distinction between so called soft clipping where the peaks are first compressed before they simply don't result in any further increase in output seems to me a false one as harmonic distortion will rise rapidly in either case when the amplifier is pushed into overload. Therefore a nominally rated 60 wpc tube amplifier shouldn't be expected to perform any better than a 200 wpc solid state amplifier whose distortion versus power output curve rises more steeply. It's that curve which defines the usable limits of the amplifier in real use, not the nominal wattage rating, the desire by consumers for simplified numbers to replace more complicated notions notwithstanding. Therefore the idea that because one type of amplifier clips with predominantly even order harmonics while another clipps with odd order harmonics seems meaningless. One very important characteristic is the speed with which an amplifier recovers from overload and this is usually a measure of the conservativeness of its power supply. The faster the recovery, the less audible an event but this demonstrates how important it is to "engineer" a sound system rather than throw one together like a tossed salad picking individual components on their own without any thought to how they will work together. The low powered SET, an exceptionally poor value on today's market, is unsuitable for use with the overwhelming majority of loudspeakers playing most kinds of music under most circumstances. Their viable only use is relegated to the most efficient speakers available.

The measurement of actual power output is far more complicated than simply measuring the voltage and assuming the speaker is 8 ohms or 4 ohms. A impedence versus frequency plot will show that the impedence for most speakers varies all over the place while a pole zero diagram will show it's phase angle does too. Therefore, to know how much actual power is delivered to the load, a meter would have to measure the voltage, the current, and the phase angle and compute the result by the well known formula P=V*I*cos theta. Will the meter in the article do this? A slightly less accurate measure is the VAR or Volt-Amp-reactive product which omits the phase angle. This can be useful in determining if transformers have been overloaded since they are often specified that way. The proof that the so called power meters on amplifiers are useless can be easily demonstrated by disconnecting the speaker. The meters will swing back and forth just as they normally do even with the actual power output at zero. People do like to look at them anyway.

This post is made possible by the generous support of people like you and our sponsors:
  McShane Design  

Follow Ups Full Thread
You can not post to an archived thread.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]