Long time ago, I designed an amplifier protection circuit based on the simple idea that when an amplifier works correctly its output signal is the exact image of the input one.
My amplifier was a pretty good one, at this time. Very low measured distortion, 2X 150W RMS, 3Mhz at -3dB, powered with a 1200 W transformer and a lot of big CAPs, with > 1 square cm copper bars to feed the + & - rails inside. High dumping factor, big speaker's wires.
And my enclosures had ~ 96dB/W of efficiency.
The circuit was added to this amp, charged on 6 Ohms resistance and tuned with a safety margin for it fires with visible clipping on my scope (10% of distortion ?).
Now, I tried the assembly with music and my enclosures, and, at loud but normal listening level, the protection fired-up at the first kick drum impact.
Back on the resistance, it was stable. So, I measured the peak signal at the moment it fired-up with my enclosures: Oh, Lord, it was a LOT under the max level. A lot.
Now, I use this circuit (witch subtract the input signal from the output one, after having them both tuned at the same level) to look in real time at the errors. And you can listen to this signal. Very interesting and not agreeable to listen-to.
All that to say that the measurements we ordinary use to evaluate a power amplifier (distortion with continuous sinusoidal signal at input) are not accurate to reflect the reality.
I don't understand why we don't use standard samples of music, recording output signal and comparing (In the digital world) the input and the output signals, with an accurate and standard way to put numbers on the levels of errors.
If it was so, i should rely on those numbers, reading "reviews" in magazines.
I believe that the company which will produce such an equipment, and succeed to make this stuff as a measurement standard near AES will make a lot of money ;-)
Yes, the problem is not measurements, but the accuracy of the ones we use to figure-out what happens in the real world when we listen to music.
My amplifier was a pretty good one, at this time. Very low measured distortion, 2X 150W RMS, 3Mhz at -3dB, powered with a 1200 W transformer and a lot of big CAPs, with > 1 square cm copper bars to feed the + & - rails inside. High dumping factor, big speaker's wires.
And my enclosures had ~ 96dB/W of efficiency.
The circuit was added to this amp, charged on 6 Ohms resistance and tuned with a safety margin for it fires with visible clipping on my scope (10% of distortion ?).
Now, I tried the assembly with music and my enclosures, and, at loud but normal listening level, the protection fired-up at the first kick drum impact.
Back on the resistance, it was stable. So, I measured the peak signal at the moment it fired-up with my enclosures: Oh, Lord, it was a LOT under the max level. A lot.
Now, I use this circuit (witch subtract the input signal from the output one, after having them both tuned at the same level) to look in real time at the errors. And you can listen to this signal. Very interesting and not agreeable to listen-to.
All that to say that the measurements we ordinary use to evaluate a power amplifier (distortion with continuous sinusoidal signal at input) are not accurate to reflect the reality.
I don't understand why we don't use standard samples of music, recording output signal and comparing (In the digital world) the input and the output signals, with an accurate and standard way to put numbers on the levels of errors.
If it was so, i should rely on those numbers, reading "reviews" in magazines.
I believe that the company which will produce such an equipment, and succeed to make this stuff as a measurement standard near AES will make a lot of money ;-)
Yes, the problem is not measurements, but the accuracy of the ones we use to figure-out what happens in the real world when we listen to music.
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I find it quite hard to tell which type of inlet receptacle those are intended for.
Those power cords are huge. One can fit chipamp inside one of them to make music.
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We all hear differently, have different liking to music, have different choices of equipment, So can we ever agree on perception ? A common guideline to how far measurements are worth pursuing and how much to agree/disagree (which requires collaboration) the subjective listening perception of other individuals would be fruitful discussion. Provided there is no commercial interest only genuine liking to the audio hobby.
Regards.
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We all hear differently, have different liking to music, have different choices of equipment, So can we ever agree on perception ? A common guideline to how far measurements are worth pursuing and how much to agree/disagree (which requires collaboration) the subjective listening perception of other individuals would be fruitful discussion. Provided there is no commercial interest only genuine liking to the audio hobby.
Regards.
Excellent points, I have no problem with the guys in the full range horn/DHT/SET crowd but why bring in the diatribes against DBT? These things usually have distinctly colored sonic signatures and the best one can do is sort preference.
I'm equally cool with the crowd that wants to narrow the field to the basic acoustic to electronic and back mechanical devices as being the most worthwhile place for improvement.
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The old von Recklinghausen law comes into mind:
"If it measures good and sounds bad, it is bad. If it Measures bad and sounds good, you've measured the wrong thing."
I prefer Pirsig, at least when it comes to our subjective enjoyment of reproduced music.
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." —Robert Pirsig, Zen And The Art of Motorcycle Maintenance
se
Indeed.
At the level we are, nowadays, in electronic, I thing we better concentrate our efforts and imagination to try to find better solutions for electro-acoutic transducers. We drive Ferrari with wooden wheels ;-)
Did we have to drive this cable up to the nuclear central ? Or just to plug-it after the two little poor cables feeding our AC outlet ?
That cable is a bit of an overdo, don't you think?
I mean, I like big quality cables, but that calibre is not usually seen outside big power generating facilities. But then, I do have 230 VAC, so this far, I make do with 6 mm.sq cables, capable of 50-60 Amps continuous. And I do have that same size bringing the power in from outside the apartment.
I mean, I like big quality cables, but that calibre is not usually seen outside big power generating facilities. But then, I do have 230 VAC, so this far, I make do with 6 mm.sq cables, capable of 50-60 Amps continuous. And I do have that same size bringing the power in from outside the apartment.
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