To get the 140 Hz crossover producing a decent RTA, I had added a 7dB boost at 174 Hz in the sub response. I figured this was "OK" because of the 140 Hz crossover, certainly by 174 Hz the crossover was already applying more than 7dB of attenuation, this was just providing a bit of boost in this region where the sub itself was starting to roll off, but not hugely rolled off yet.
But when I was listening to the Saturday night program featuring local concert performances called Performance Saturday on KPAC, announcer Nathan Cone's voice seemed to have a lot of added upper bass delayed resonance. The kind you might imagine, say, from a 1930's large cabinet radio.
OK, I immediately figured this had to do with the boost. So I dialed back the boost, and re-listened to the radio program I had recorded digitally from my FM radio onto my Marantz state recorder. (Pity me having to listen to the preceding 5 minutes of music over and over for these tests--marvelous music--but anything gets tiring in a situation like this.)
I thought it sounded better, but the upper bass resonance had NOT entirely gone away.
I tried it with the boost again. I thought it was worse again, but now it was getting really hard to tell. That's the way it goes, for me, with A/B audio tests. If I even listen to B at all, I start getting confused, and by the time I've listened to A/B/A, I am really confused.
When I just want to move forwards with something I know is an objective improvement, I don't bother trying to do an A/B test at all. I just set up B--which often takes awhile--and start listening to it. Days later, if there's clearly something wrong with B, I may go back to A or try to move on to some further refinement of B which is C. And so on.
I find listening tests so inconclusive I don't put much faith in them. I'd also hate to predjudice my judgement against what is likely to be a step forwards with a quick but possibly false snap judgement against it. But I've known people who take the opposite stance, intended to do A/B/A test, but finding B so much clearly better they don't need to go back. Just forwards. I find that very suspicious actually. Strong result claims need better, not lesser, validation.
Anyway, as I was dialing back the A, I noticed something. As part of the previous day's testing, I had never re-enabled the midrange EQ on one channel. It was bypassed. I completed the A/B/A test sequence anyway, which I felt had some internal validity even if the conditions were way off.
Then I went back to re-enable the midrange EQ, and I noticed something else. I had never restored the 140 Hz crossover for the subwoofer, I had left it with the 300 Hz crossover I had dialed in for testing purposes.
It was THAT which had distorted the sound of Nathan Cone's voice the most.
What may be happening in the subwoofer as the frequency rises above 160 Hz or so, the subwoofer's 13 inch cone starts becoming directional. It measures fairly flat to 300 Hz...but only on-axis. Of axis, the increasing directionality means that midbass in that region is less radiated toward the listening position, but more towards a wall reflection.
Well, that's another theory I have but not really well established yet.
But concluding the boost was THE problem was wrong. It's even hard to know how much it was a factor. I generally don't like to boost anyway, but it's unclear how much bad this experience shows it to be a problem. I could have just been mistaken.
I have often found longstanding "conclusions" to have been caused by some mistake, exactly like this, but sometimes long after.
For that reason, things would need to be tested and retested for firm conclusions. I avoid that problem by resisting firm conclusions generally, especially in things that don't make sense to me.
But when I was listening to the Saturday night program featuring local concert performances called Performance Saturday on KPAC, announcer Nathan Cone's voice seemed to have a lot of added upper bass delayed resonance. The kind you might imagine, say, from a 1930's large cabinet radio.
OK, I immediately figured this had to do with the boost. So I dialed back the boost, and re-listened to the radio program I had recorded digitally from my FM radio onto my Marantz state recorder. (Pity me having to listen to the preceding 5 minutes of music over and over for these tests--marvelous music--but anything gets tiring in a situation like this.)
I thought it sounded better, but the upper bass resonance had NOT entirely gone away.
I tried it with the boost again. I thought it was worse again, but now it was getting really hard to tell. That's the way it goes, for me, with A/B audio tests. If I even listen to B at all, I start getting confused, and by the time I've listened to A/B/A, I am really confused.
When I just want to move forwards with something I know is an objective improvement, I don't bother trying to do an A/B test at all. I just set up B--which often takes awhile--and start listening to it. Days later, if there's clearly something wrong with B, I may go back to A or try to move on to some further refinement of B which is C. And so on.
I find listening tests so inconclusive I don't put much faith in them. I'd also hate to predjudice my judgement against what is likely to be a step forwards with a quick but possibly false snap judgement against it. But I've known people who take the opposite stance, intended to do A/B/A test, but finding B so much clearly better they don't need to go back. Just forwards. I find that very suspicious actually. Strong result claims need better, not lesser, validation.
Anyway, as I was dialing back the A, I noticed something. As part of the previous day's testing, I had never re-enabled the midrange EQ on one channel. It was bypassed. I completed the A/B/A test sequence anyway, which I felt had some internal validity even if the conditions were way off.
Then I went back to re-enable the midrange EQ, and I noticed something else. I had never restored the 140 Hz crossover for the subwoofer, I had left it with the 300 Hz crossover I had dialed in for testing purposes.
It was THAT which had distorted the sound of Nathan Cone's voice the most.
What may be happening in the subwoofer as the frequency rises above 160 Hz or so, the subwoofer's 13 inch cone starts becoming directional. It measures fairly flat to 300 Hz...but only on-axis. Of axis, the increasing directionality means that midbass in that region is less radiated toward the listening position, but more towards a wall reflection.
Well, that's another theory I have but not really well established yet.
But concluding the boost was THE problem was wrong. It's even hard to know how much it was a factor. I generally don't like to boost anyway, but it's unclear how much bad this experience shows it to be a problem. I could have just been mistaken.
I have often found longstanding "conclusions" to have been caused by some mistake, exactly like this, but sometimes long after.
For that reason, things would need to be tested and retested for firm conclusions. I avoid that problem by resisting firm conclusions generally, especially in things that don't make sense to me.
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