Myths about subwoofers

S

shadyJ

Speaker of the House
Distortion can give a sub's position away too, as a lot of that is frequencies above 80 Hz. Many of the smaller subs are basically harmonic distortion generators past a very modest loudness level.
 
TLS Guy

TLS Guy

Audioholic Slumlord
What makes a half space radiator locatable?
This problem has received a lot of attention in professional circles of late. We now know that bass can be and frequently is able to be localized, but as is the case there are the usual variables.

Bass does have to radiate to full space to not be localized easily. To do that it needs to radiate in free space of the room. It will transfer to a half space radiator at 380 divided by the width of the cabinet in feet. So a big sub say 3 ft wide will transition at 126 Hz. Now the filters are not brick wall, and the sub will have significant output an octave above. So a crossover set to 80 Hz the output will not be negligible until 160 Hz.

If you put it against a wall then the wall becomes part of the dimension of the cabinet.

The other big factor determining whether or not you can localize a sub is the room. The better the room the room the greater the chance of localizing the sub. In a room with powerful bass reflections you are less likely to localize the subs.

The bigger the room the more likely you are to localize a sub.

The take home is that it is a myth that bass frequencies are not able to be localized by the human ear. Circumstances will vary.

In the open air you can easily localize deep bass. Pretty much everyone can localize the low rumble of distant thunder. You can easily tell the direction it is coming from.
 
S

shadyJ

Speaker of the House
Thunder isn't just 80 Hz and under rumbles, so that doesn't make for the best example. Anyway, this is an interesting subject, and one that I think Audioholics could develop into a good article pretty easily. All you would have to do is setup a sub system where the bass is under 80 Hz, test it with a mic and some measurement gear to be sure, and blindfold some people and ask them where they think the bass is coming from. The results would be informative no matter what the outcome.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Thunder isn't just 80 Hz and under rumbles, so that doesn't make for the best example. Anyway, this is an interesting subject, and one that I think Audioholics could develop into a good article pretty easily. All you would have to do is setup a sub system where the bass is under 80 Hz, test it with a mic and some measurement gear to be sure, and blindfold some people and ask them where they think the bass is coming from. The results would be informative no matter what the outcome.
When thunder is way off in the distance it is all very low frequency. You can tell the direction it is coming from.
 
U

utubecomment21

Audioholic Intern
Ported subs are louder than sealed.

YouTube: Pipo Sanchez and see what sealed set up can do


Statements from links given

Sensitivity is very important for subwoofers. - http://www.data-bass.com/myths

At the very least, I would say; highly debatable. At the most; Wrong! ! A subwoofer in isolation (without baffle/enclosure) is a 'near soundless air-pump'. This Sundown X & Z (Sundown X-10 77.64 dB) type have low dB one watt figures, however when it comes to dB SPL, they're up there!


Cone material affects the sound

50/50. I would say cone weight in relation to other T/S parameters .... and that does matter!

Often times larger drivers require less amplification

er, since when? from car audio to PA audio, both shove huge power into the respective subs, high sensitivity or not. Why is it my DJ friend has runs subs on 1k plus, and his subs are around 10dB more sensitive than my car subs!
 
Auditor55

Auditor55

Senior Audioholic
How about the Subwoofer Crawl Test. It isn't always practical and its not the be all end all application that people make it out to be. For example, how you're going place this at ear level on the sofa.:confused:



Epik Conquest.
 
F

fmw

Audioholic Samurai
It is hard to find subjects with more myths than home audio. The misinformation is astounding.
 
HTfreak2004

HTfreak2004

Full Audioholic
One of the best ways to determine sub placement is to first determine the trouble frequencies. Take the room length in meters and divide it by the speed of sound in meters. My room is (20.4 ft/ 3.28 ft/m)
Length in meters is 6.22 rounded divided by speed of sound at 343.2 meters per second so I have 55 hz as a trouble frequency half octave 27.5 hz double octave 110 hz. I do not want to crossover my mains and sub at these frequencies as it doubles the power at that frequency. Now it is important to know that furnishings make a massive impact on room shape and because most subs are lower to the ground than mid range speakers and tweeters, the sound wave is intercepted by objects in the path causing dispersion. This can be useful in breaking up the trouble frequencies inherent with frequencies under 200 hz. Remember sound is omnidirectional and the reflections of side walls in your listening area will either add to the sound re-enforcement or have a cancellation effect. This tends to be a major reason why some serious HT owners and audiophiles prefer multiple subs so the bass can be balanced over the width of the room with more consistency and the sub can be located mid way or beside the listening area. If the sub was dead centre where the centre channel normally sits or below it it would be technically balanced but have no side wall re-enforcement. If it is nearer the left or right main speaker then the bass wave reflects off the closest side wall first. Place the sub in the listening area position first then go to the sound stage part of the room and listen to where the bass sounds the loudest and most solid. That is where you want the sub in a single sub setup. That is a reversal of listening position between you and the sub and is good to get the closer to correct distance and placement to minimize bass loss and trouble frequencies. On a last point sound reaches the ear in my room in about 1/100th of a second which is going to be an average as my room is a Medium size at only 1733 cft. This room is very easy to overpower so bass management really improves the experience. Usually I find my mains and surrounds are ample but the sub does tie it all together like a speaker that doubles the power should. If your receiver or amp has say 1800 watts for all speakers then using a sub with an rms output of around that gives you great headroom considering the room size is included and isn't beyond the speakers performance ceiling. That's what works for my setup.


Sent from my iPhone using Tapatalk
 
Verdinut

Verdinut

Audioholic Samurai
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.
Greetings!
I figure that this SACD you are referring to is on the BIS label. Am I right?

Also, I wanted to mention that I recently installed three Dayton RSS390HF-4 subwoofers in the 3 cabinets which form the three front channels on my cinema system. They are in 7.5 cf cabinets tuned at 16.8 Hz. According to BassBox Pro, I should be getting an F3 of 20 Hz approximately. I figure that I should be able to get a flat 20Hz with active graphic EQ in the near future.

So far, I am satisfied with those RSS Series subs. I also built 2 three-way systems using the RSS315HF-8 with excellent results.

I am curious. Have you had experience with the RSS390HF-4?

Finally, if you like the Saint-Saëns Symphony No. 3, there is an excellent Reference Recordings SACD with the Kansas City Symphony under Michel Stern. You may already have it.
There are several 32 foot stop notes from a Casavant organ, a Canadian factory which has been in existence for more than 100 years.
For your info, that company is world renowned and it recently signed a contract to build 40 organs to install in China.

Thank you in advance. By the way, you have quite an interesting studio.

It's good to exchange positive comments and our common passion.

André
 
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Jivinjoe

Jivinjoe

Audioholic Intern
So much to learn, this was helpful for me looking into a new subwoofer and placement
 

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