Qtc for music

I don't know the theory of now, but back a few decades ago when I first played around with DIY speaker building .7 was the goal of accurate bass for music in a sealed system. I know things change but for my old ears I still like the sound of some of the classic builds of speakers and amps.

for a sealed subwoofer configuration, the q of the system determines how much damping there is.

the lower the q, the more quickly the system will return to its initial state. the higher the q, the longer it will resonate.

most people untrained in listening like a higher q as it makes explosions in movies really resonate, same with the hip hop bass heads--mo is betta.

those with a critical ear listening to an upright bass or cello don't want any more resonances what is in the recording, so they are most pleased with a very low q.

so, there really isn't a universal better or worse. accurate vs. enjoyment. i have no idea how to reconcile the two other than to say it kind of depends on the person, their preferences, and the recording.

or put another way, what sounds better to you, might not sound better to me. that doesn't make either one of us more right or wrong...

It was, but that was before the advent of modeling software. Now you model the driver/box and let the Q end up where it may for the desired result.

Yeah, my son does installs for car audio and some of his models are way out of the ball field I was playing in decades back.

I prefer flat in-room response.

I shoot for 3. At least.

When I design a sealed cab I don't pay much, if any, attention to Q.

Changing response via EQ changes final system Q.

"Changing response via EQ changes final system Q."

+1, but not completely.

Identical final response curves have, by definition, identical final Q. It doesn't matter how you get there.

Unlikely to achieve identical curves using eq on two different alignments (unless a tailored eq like a linkwitz transform), but it illustrates the problem with the question.

That's not the case. You can use drivers with different specs in different cabs to arrive at identical response curves with very different Q values, or identical Q values and very different response curves. That's why I pay little mind to Q, as arriving at a set Q value is not a worthwhile goal in and of itself. Q is defined by the driver and enclosure, and is unaffected by external factors such as EQ. EQ will change response, emulating a change in Q, but it won't affect all of the other factors that an actual change in Q by modifying the enclosure will result in.

Bill, you're speaking nonsense. You can have two different response curves with the same q (obviously, as a high pass response and a low pass response can have the same q), but two identical response curves by definition will also have the same q.

And what other factors are you speaking of that are only affected by changes in "actual" q? RLC effects are just as real as MKD effects. EQ doesn't emulate a change in q, it IS a change in q. The whole system is electromechanical. You can't ignore half the system.

I'm not sure what Q you're referring to. I'm referring to Qtc of a sealed speaker, to which your comments do not apply.

I'm speaking of the q you actually hear, the one defined by the final response of the speaker. I don't see the point in talking about qtc when that isn't what we hear when eq is in play. Changing q electrically has the same effect in both frequency and time domains as were it achieved by driver and alignment alone.

Which is what the question specifically stated... q in the context of eq. To which my answers assuredly apply. So why are you talking about something else?

Not as I understood it; he did specify Qtc. To clarify for those interested, neither EQ nor any other form of processing alters the Qtc, and therefore the transfer function, of a speaker.

Maybe a misunderstanding of what is being discussed. The original question was about qtc. Once eq is introduced we aren't talking about qtc as you can't hear it in isolation. You only hear final q, effective q, effective qtc, or whatever other name you wish to apply to it. In any case, once he asked about eq and what was preferred it was correct to point out that by altering frequency response you alter q. You seemed to object to this, even going so far as to make flatly wrong statements such as two enclosures with the same response can have different q, and also suggesting that electrically altering q somehow doesn't produce the same effects as altering "actual" q via enclosure alignment.

I suspect these comments simply arise from a common tendancy to forget that eq alters time domain behavior just as it does frequency domain, and changing q electrically has the same effects on ringing etc as does altering it via alignment.

To the original poster: given access to in-room measurement and PEQ, the box's qtc only really matters in the context of driver choice, box size, available power, and desired output SPL and bandwidth, and is not directly applicable to final sound quality. What you actually hear at your seat is the combination (well, technically, convolution...) of system and room responses.

In short, don't worry about the "sound" of a particular box qtc. Build the box according to your application constraints, measure it in the actual position in the actual listening room at the actual listening position(s), and move and/or (parametric) eq accordingly. Because that's what you finally hear. Qtc is a useful measure, but not nearly as useful as many would have you believe.

Not the Qtc of the speaker. Yes, system response will be altered, but only by dint of the alteration of the signal going into the speaker. That's an entirely different proposition than actually changing the Qtc of the speaker by either making the cab larger or smaller, or by adding stuffing, which alters F3, excursion, sensitivity and maximum SPL. EQ has no effect on those parameters.

Well of course. How else could it work? But he asked about sound preference of the alignments. Who cares about qtc when eq is on board and the question is about how various Q's sound.
Not different when the question is about how a particular q sounds in the presence of eq. That was the question. You don't hear qtc, you hear the final q. There may be peripheral differences regarding power compression and other thermal effects, amplifier distortion, etc, but that wasn't the question.
F3 is certainly affected by eq, and theoretical max spl in a sealed system (what the thread was about) as frequency lowers is not altered by box size. Efficiency of course changes. No one has suggested a cheat to Hoffman's law.