Myths about subwoofers

[UT_EE]

Nice article, much appreciated!

[Cpyder]

Overall a good read! I feel like the author is speaking in extremes for some of the points though.

"One of the biggest myths about woofers is that 8’s and 10’s are “tighter” and “cleaner” than 15’s or 18’s. Nothing is further from the truth."

Smaller subs do sound tighter, however. It's true that all subs will move at the same frequency for each note but sometimes that note isn't played long enough for the driver to fully respond. If there's a bass hit that lasts for 1/10 of a second, a smaller sub, like a 6.5" driver will be able to respond more accurately because it will be able to accelerate faster than a large sub (like an 18" for example) Over the same time interval the larger sub may not have been able to change it's velocity (accelerate) sufficiently. It's simple physics. Why do you think you use a tweeter for highs and subs for lows. They cannot share jobs.

"So in conclusion, the only reason to use a smaller bass driver is for space, weight and potentially power considerations..."

Does everyone agree with this?

Also, one reason so many people say smaller subs are faster/cleaner etc is because of the same reason a piano sounds different than a violin. It has to do with harmonics. When you play a middle C on a piano and violin, you don't just get a frequency of 263hz (or whatever a middle C is - I think it's around this frequency). You get that note plus all the other harmonics at higher frequencies. Smaller subs have different harmonics than larger ones. Hence, they sound different when playing the same notes as larger ones. This is also one reason why people say larger subs sound "boomy."

"Your subwoofer driver does not have a conscience, and it does not perform better with one type of music over another"

I cannot agree with this. Surely some subs sound better with certain types of music that other subs. I can attest for this myself as I have had 12s, 15s, and 6.5s in my car and certainly thought some songs sounded a lot better with different subs. The 6.5s make my want to blow a load with higher frequency snappiness. And the larger subs, I found, were better with lower, longer bass notes.

Reflect your thoughts. Am I crazy?

[TLS Guy]

Overall a good read! I feel like the author is speaking in extremes for some of the points though.

"One of the biggest myths about woofers is that 8’s and 10’s are “tighter” and “cleaner” than 15’s or 18’s. Nothing is further from the truth."

Smaller subs do sound tighter, however. It's true that all subs will move at the same frequency for each note but sometimes that note isn't played long enough for the driver to fully respond. If there's a bass hit that lasts for 1/10 of a second, a smaller sub, like a 6.5" driver will be able to respond more accurately because it will be able to accelerate faster than a large sub (like an 18" for example) Over the same time interval the larger sub may not have been able to change it's velocity (accelerate) sufficiently. It's simple physics. Why do you think you use a tweeter for highs and subs for lows. They cannot share jobs.



"So in conclusion, the only reason to use a smaller bass driver is for space, weight and potentially power considerations..."

Does everyone agree with this?

Also, one reason so many people say smaller subs are faster/cleaner etc is because of the same reason a piano sounds different than a violin. It has to do with harmonics. When you play a middle C on a piano and violin, you don't just get a frequency of 263hz (or whatever a middle C is - I think it's around this frequency). You get that note plus all the other harmonics at higher frequencies. Smaller subs have different harmonics than larger ones. Hence, they sound different when playing the same notes as larger ones. This is also one reason why people say larger subs sound "boomy."

"Your subwoofer driver does not have a conscience, and it does not perform better with one type of music over another"

I cannot agree with this. Surely some subs sound better with certain types of music that other subs. I can attest for this myself as I have had 12s, 15s, and 6.5s in my car and certainly thought some songs sounded a lot better with different subs. The 6.5s make my want to blow a load with higher frequency snappiness. And the larger subs, I found, were better with lower, longer bass notes.

Reflect your thoughts. Am I crazy?

Yes you are under some misapprehensions.

Whether bass is tight or not has nothing to do with driver size, but the total system Qtc. If it is around 0.5 it will be tight. It will be very boomy and muddy over 0.8.

You are also confused about fast bass. A woofer is incapable of producing any attack transient by itself. A sharp transient requires the ability to at least produce a facsimile of a square wave. Even a 20 Hz square wave requires a substantial high frequency component to reproduce it. So fast bass from a sub is in and of itself an oxymoron. Any sub cut in below 80 Hz, is incapable of producing a transient by itself. The reason is that if you do Fournier analysis the sharp up stroke of even a very low frequency has a strong high frequency component.

There for the sharp attack comes from a sub with low Qtc integrated well with the other speakers. In fact the later is very hard to achieve. That is why I have designed and built true full range speakers and go subless. If you click on my signature you will see the speakers.

On an SACD of the opening of Aho's symphony number 12, there is a lot of Laplander rhythmic drumming, that requires superb bass attack. I'm unable to get even very expensive systems at high end dealers to reproduce this disc anything close to realistically. In fact it is widely reported on the net the disc is poorly engineered. I can assure you it is not, it is a tour de force. there are just few systems on the planet, that can likely reproduce it.

[Cpyder]

Is achieving a good Qtc dependent or independent of driver size?

[TLS Guy]

Is achieving a good Qtc dependent or independent of driver size?

It is independent.

[Erika111]

Of course, this is a pure function of frequency response. One can for example, take a woofer and put it in a very tiny sealed box, effecting a Qtc of 2, and it can then be corrected with electronic line level filters to make it in effect a QTC of 0.7 or any other response target

[annunaki]

Of course, this is a pure function of frequency response. One can for example, take a woofer and put it in a very tiny sealed box, effecting a Qtc of 2, and it can then be corrected with electronic line level filters to make it in effect a QTC of 0.7 or any other response target

Very true, but again a set of compromises/requirements comes into play. In doing such said driver must have substantially low power compression, long linear excursion capability, and of course, loads of power on tap. That is assuming one would like the driver usable to the 20hz range.

VERY, VERY FEW drivers fit said requirements. It is definitely not an efficient approach.

[WmAx]

Very true, but again a set of compromises/requirements comes into play. In doing such said driver must have substantially low power compression, long linear excursion capability, and of course, loads of power on tap. That is assuming one would like the driver usable to the 20hz range.

VERY, VERY FEW drivers fit said requirements. It is definitely not an efficient approach.

Annunkai makes a great point. VERY FEW drivers are truly suited to the small sealed application. A few suitable examples: JL W7, TC Sounds TC2000(AP REVO), TC3000(AP AXIS), LMS5400( AP ULTRA LMS), R.E. Audio XXX, etc.

The TC Sounds LMS drivers (Sound Splinter has LMS technology drivers made by TC for them, re-badged as SS) are the best drivers for this application at any price to my knowledge; this is based on 3rd party analysis of the actual driver performance in acoustic tests and objective analysis of the motor system. The LMS offers the absolute longest true linear stroke of any known driver and has massive thermal dissipation capabilities.

-Chris

[TriMe]

thanks for posting this article - like it.

[ddemetrius456]

cool man...its really useful and informative.