Madison PA-A203 amplifier

  • Thread starter Thread starter Hazardsneon
  • Start date Start date
Power ratings are always referred to some percent of harmonic distortion. Most power amps will put out quite a bit more than their rated power with more distortion, at least until they overheat. I suppose you could just run it up until you see the waveform start to flat top for an approximation. Also, music is different from sine waves. What an amp does at 1kHz doesn't say a lot about what it does at the lower extremes of the audio spectrum. What kind of test signal are you using?
 
bouldersoundguy said:
Power ratings are always referred to some percent of harmonic distortion. Most power amps will put out quite a bit more than their rated power with more distortion, at least until they overheat. I suppose you could just run it up until you see the waveform start to flat top for an approximation. Also, music is different from sine waves. What an amp does at 1kHz doesn't say a lot about what it does at the lower extremes of the audio spectrum. What kind of test signal are you using?
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now that you mention it ..... he does need to take those voltages at the point right before the tops of the waveforms start going flat .... that still seems like more than I would expect from that amp and if he was running it into clipping that would account for the extra.
 
I don't really have the technology yet to measure the % THD unless you can enlighten me with techniques on a scope but like I said on my post I watched the scope and made sure to measure just before clipping. I plan on playing around with a program I found that supposedly tests %THD and a battery of other amplifier quality tests called Rightmark Audio Analyzer. It utilizes a PC's sound card which isn't as good as "real" equipment but it will give me more information than I currently have and it shouldn't be that inaccurate.

With reguards to signal input, it is noted in my post. Aren't most amps tested with 1kHz sine waves?
 
Sorry, I missed that bit of info.

Running 1kHz up to clip (defined by some %THD) is just one test of an amp. Pink noise is also used. Musical signals are complex and variable, and the amp may get used in a lot of different ways so no single test tells you enough. A sine wave has a crest factor (peak to average ratio) of about 3dB while music, especially live music, usually has a much higher crest factor, higher peaks for the same average power.
 
I believe the new version of Room EQ Wizard has THD measurement capability.
 
Hazardsneon said:
I don't really have the technology yet to measure the % THD unless you can enlighten me with techniques on a scope but like I said on my post I watched the scope and made sure to measure just before clipping. I plan on playing around with a program I found that supposedly tests %THD and a battery of other amplifier quality tests called Rightmark Audio Analyzer. It utilizes a PC's sound card which isn't as good as "real" equipment but it will give me more information than I currently have and it shouldn't be that inaccurate.

With reguards to signal input, it is noted in my post. Aren't most amps tested with 1kHz sine waves?
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while boulder is correct in every thing he's saying ..... I really do see LOTS of amps that only give a rating done with a 1khz sine wave.

For the purposes you wanted to accomplish .... to have an idea of what fuse you needed and a general idea of how much power it puts out I would think that's sufficient.
 
In my old days of PA systems (1970's 1980's) the amps we used were rated at 300 watts a channel, I had the amps tested by a tech and they were a real 300 watts a channel at 4 ohms. However 1 thing we found was that if only 1 side was tested (no signal on the other side) we could get 360 watts from the single channel. We put this down to the power supply only having to power 1 side of the amp.

As we had electronic crossovers in our system (so that different amps run highs mids and subs), we then came up with the idea of using one side of the amp to run subs and the other to run the horns, the subs pull a big load from the amps but the horns are very easy on the amps, we found we got more power (volume) out of the amps this way.

Alan.
 
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