The small cheap sub will probably have more audible harmonics above 80hz from THD and Fletcher-Munson then the stuff below
80hz. Not a fair comparison.
Historically [at least here in USA before moving the industry ~offshore], quality assurance [QA] programs for these types of products measured its efficiency at some point on a curve that apparently resulted in a ~ -10%, +0% based on numerous Fs measurements of all sizes/types of point source drivers, so no need for break-in for the reason you assume.
Other than the late Avatar/Adire Audio, no clue how [QA] was/is done in recent decades.
GM
Linkwitz transform, perfect for prototyping this, completely ignored by the others.
You are spot on. Sadly I don't think many people appreciate the simplicity and brilliance of what you just said. Clearly the way to go. Use the Linkwitz spreadsheet, build a few digital filters and load them into a PC or miniDSP or something and listen to what ever damping you desire. It could be done at various frequencies. Another approach is to just create a high pass filter and listen to the various configurations with headphones with sufficiently extended low end.
You are spot on. Sadly I don't think many people appreciate the simplicity and brilliance of what you just said. Clearly the way to go. Use the Linkwitz spreadsheet, build a few digital filters and load them into a PC or miniDSP or something and listen to what ever damping you desire. It could be done at various frequencies. Another approach is to just create a high pass filter and listen to the various configurations with headphones with sufficiently extended low end.
Which could be taken by constant current, or by constant voltage, at a variety of drive levels, all yielding somewhat different numbers. Then you have driver-to-driver production variance. Then you have "adjusting" the numbers for marketing purposes, on up to complete nonsense.
--> It does not really make sense to worry too much about small differences in calculated box sizes or Q in the box or whatever.
(Even though that's exactly what I did when I started as a loudspeaker engineer, until cold reality set in
)- Also because T/S parameters are a MODEL and the reality is more complicated.
- I have seen a couple of tests showing significant drop in resonance from break-in...I consider that not a great design, frankly. My experience testing some woofers over time, and most extremely I think it was a gross of 5x7s slammed stop-to-stop at full power for 280 hours. Resonance did indeed drop, and continually so, but the change to resonance and parameters and frequency response were not huge. [Note that Fs is proportional to 1/(square root of Cms) so the effect of a change in compliance is reduced]
If you really want to get picky, then ya gotta measure your individual parameters-after ha ha deciding on which flawed method you want to use...
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I am a novice when it comes to these things but surely the 'sound' of a sub as defined by terms like 'muddy' and 'slow' has very little to do with the driver. Receipt of low frequencies is not limited to audio. The vibrations travelling through concrete or wood reach the listener at 10x the speed of those travelling through air - this may contribute to any perceived muddiness or slowness.
Unless you're listening to sign waves, the majority of the texture of bass sounds is not the responsibility of the sub-woofer. Beyond the fundamental frequency the timbre is produced by the overtones that are output by higher frequency speakers.
Unless you're listening to sign waves, the majority of the texture of bass sounds is not the responsibility of the sub-woofer. Beyond the fundamental frequency the timbre is produced by the overtones that are output by higher frequency speakers.
Thiose charactes have a myriad of causes Driver, box, amp driving them (amplifier Zout has to be suitable for the driver/box), room, room placement, what the source is even.
dave
Very interesting point about vibrations through the room structure, I've never seen that before. Delayed energy could come out of that as well. And the "speed"* of the bass probably has more to do with the midbass rolloff of the sub plus integration to the mains. I wouldn't absolve the subwoofer, however, even though it IS almost Easter
. The sub can certainly "ring" on low notes depending on the design.
In what context? Sealed box fullrange? Sealed box subwoofer? (If so, with external 1st order filter? Or passive capacitor?) Or are you talking about crossover between midrange and woofer or woofer to tweeter or etc etc?
Nothing the least bit "critical" or even desirable about the magic number. Just a numerical convenience.
The proper Q for reproducing a recording is zero. You want your speakers to have no voice of their own. And if they have a voice of their own (which is hard to avoid), it should be outside their passband.
B.
The proper Q for reproducing a recording is zero. You want your speakers to have no voice of their own. And if they have a voice of their own (which is hard to avoid), it should be outside their passband.
B.
If the Q is zero, then the driver’s Qms is close to zero (unfnistly damped) such that the cone can no longer move. So on the fce of it that statement is somewhat hard to believe (or understand).
dave
The baffle has a Q based on its roll off cancellation slope and combined with the driver's Q = ? Qt. Sim/compare an IB and a simple baffle and at some baffle size the slopes matches close enough for me, so wonder if DMB can add it to OBs.
Interesting - I agree - every time I mention this fact I am shot down in flames by folks telling me this is swamped by room effects. I continue to hear systems having lots of stored energy (folded/tapped horns, ported etc.) as very poor compared with those which do not. Very fast Metallica-style bass drumming always sounds like blurry mush to me on such systems, rather than the staccato machine-gun like sound it should be. (This genre is but a tiny subset of my listening used as a pertinent example, not representative of it!). Step response seems to be so often ignored or overlooked...