Failure to do proper level matching.
That's precisely why the AudioGeorge LX55 modification doesn't work for me (or, I believe, anyone actually committed to "high fidelity").
Actually, both measurements and listening tests confirm that George's first modification, the tweeter polarity "correction" (corrected from the factory inverse polarity connection, which has no obvious explanation but was consistent) actually may improve matters, both in frequency and impulse response. It certainly sounds better than the full modification, I've confirmed that in listening tests. (I have not yet consistently compared with the factory version(s) in listening tests.)
Now all my listening tests are level matched...in this case using the weighted pink noise my Yamaha receiver puts out...for level matching purposes. I believe it is identical or close to C weighted pink noise, what is recommended by objectivist experts and gray hats such as John Atkinson.
George refused to use such things. He would only level match by ear, on the fly, adjusting level after any change to what sounded best to him. And he insisted this was the ONLY way to do this. We had a long argument about it. To me, this was endless cheating, he could make anything sound better or worse than the last at whim. To him, he was playing music to satisfy himself, so he ought to see how best each change COULD satisfy himself, by setting the level to what sounded best to him each time.
That position is hard to refute in it's own terms, I admit. The problem lies in insufficient data, and believing that your auditory perception is unbiased and uninfluenced by other irrelevant factors, such as how far your wrist is turning.
In principle, George is right, the system exists to satisfy him, so every change ought to be measured as to how well it satisfies him. The error is that in a quick twist of the knob, he has found the one and only, ultimate, and always most satisfying playback level given the state of the system.
The way the satisfaction test would really have to be done...would be to test each and every possible 0.1dB increment, from faint to blasting, in random order, under both conditions, to find the highest ranking satisfactions, and under each condition where such satisfaction ranking might vary (such as early in the morning, and after coming in from heavy traffic).
Failing to do that, he (and most subjectivists) have a strong tendency to favor the louder, because hearing bandwidth is increased for louder signals. And the tendency, when adjusting volume, is to return to the same electrical level (same rotation of the knob, etc). So if any change makes the system louder, that is immediately what is preferred.
Anyway, that explains why he finds that removing the choke makes the speaker sound better. With the same power input, it now sounds louder. Nothing in the output has been restricted by this change, only more has been opened up.
When you do the level matching, however, the part that has been opened up now dominates the level more than it did before. So, at matched level, everything else becomes LESS.
This is how, with level matching, a change which impedes nothing in the high frequency response...removing the choke on the woofer...can make the system now sound dark and univolving. Removing the choke creates a mid frequency peak, relative to which everything else is now at a lower level, including the higher frequencies.
But if you don't match the level acoustically, more more like electrically, the highs stay the same and now the midrange is WOW.
Now, the difference is easy to see, but perhaps not entire unambigous in the frequency response graph. Actually, with no choke, the highs are boosted past 10kHz! But the boosting above 3kHz is far less than the boosting at 3kHz, with the audible result I've described, level matched.
What I might not have expected was the deterioration in the step response. The step response is greatly messed up within the first 1 msec by removing the choke. So much for "simplicity" and all that. I suspect the high frequency output of the woofer is highly frequency variable, and without the choke it dominates the relatively nice tweeter output.
That's precisely why the AudioGeorge LX55 modification doesn't work for me (or, I believe, anyone actually committed to "high fidelity").
Actually, both measurements and listening tests confirm that George's first modification, the tweeter polarity "correction" (corrected from the factory inverse polarity connection, which has no obvious explanation but was consistent) actually may improve matters, both in frequency and impulse response. It certainly sounds better than the full modification, I've confirmed that in listening tests. (I have not yet consistently compared with the factory version(s) in listening tests.)
Now all my listening tests are level matched...in this case using the weighted pink noise my Yamaha receiver puts out...for level matching purposes. I believe it is identical or close to C weighted pink noise, what is recommended by objectivist experts and gray hats such as John Atkinson.
George refused to use such things. He would only level match by ear, on the fly, adjusting level after any change to what sounded best to him. And he insisted this was the ONLY way to do this. We had a long argument about it. To me, this was endless cheating, he could make anything sound better or worse than the last at whim. To him, he was playing music to satisfy himself, so he ought to see how best each change COULD satisfy himself, by setting the level to what sounded best to him each time.
That position is hard to refute in it's own terms, I admit. The problem lies in insufficient data, and believing that your auditory perception is unbiased and uninfluenced by other irrelevant factors, such as how far your wrist is turning.
In principle, George is right, the system exists to satisfy him, so every change ought to be measured as to how well it satisfies him. The error is that in a quick twist of the knob, he has found the one and only, ultimate, and always most satisfying playback level given the state of the system.
The way the satisfaction test would really have to be done...would be to test each and every possible 0.1dB increment, from faint to blasting, in random order, under both conditions, to find the highest ranking satisfactions, and under each condition where such satisfaction ranking might vary (such as early in the morning, and after coming in from heavy traffic).
Failing to do that, he (and most subjectivists) have a strong tendency to favor the louder, because hearing bandwidth is increased for louder signals. And the tendency, when adjusting volume, is to return to the same electrical level (same rotation of the knob, etc). So if any change makes the system louder, that is immediately what is preferred.
Anyway, that explains why he finds that removing the choke makes the speaker sound better. With the same power input, it now sounds louder. Nothing in the output has been restricted by this change, only more has been opened up.
When you do the level matching, however, the part that has been opened up now dominates the level more than it did before. So, at matched level, everything else becomes LESS.
This is how, with level matching, a change which impedes nothing in the high frequency response...removing the choke on the woofer...can make the system now sound dark and univolving. Removing the choke creates a mid frequency peak, relative to which everything else is now at a lower level, including the higher frequencies.
But if you don't match the level acoustically, more more like electrically, the highs stay the same and now the midrange is WOW.
Now, the difference is easy to see, but perhaps not entire unambigous in the frequency response graph. Actually, with no choke, the highs are boosted past 10kHz! But the boosting above 3kHz is far less than the boosting at 3kHz, with the audible result I've described, level matched.
What I might not have expected was the deterioration in the step response. The step response is greatly messed up within the first 1 msec by removing the choke. So much for "simplicity" and all that. I suspect the high frequency output of the woofer is highly frequency variable, and without the choke it dominates the relatively nice tweeter output.
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