Spyboy - Your thread is welcome here! Is 20 Hz all we need in a subwoofer?

[craigsub]

Guys - Yesterday, Spyboy posted a new thread. It's an interesting conversation to have.

I think the basics behind the thread is Rythmik Audio has established a baseline for the output at 20 Hz for their subwoofers.

The response on that forum has been to make fun of Spyboy for posting it.

I believe that both Spyboy and Rythmik are making the point that 20 Hz is the lowest frequency needed in order to have a great subwoofer. (Edit - Rythmik does have a 14 Hz extension setting on their sealed subs, so there is some proof that they expect a deeper in room response in certain situations, which is natural in sealed subs).

Archea has made much the same point with his captivators here.

This is not my agreeing with the premise (I think, for our subs, 16 Hz is the number), but it is worth discussing without abusing the OP.

The thread can be found here:

http://www.avsforum.com/avs-vb/showthread.php?t=1380572

Spyboy - feel free to join us here for this discussion.

[yblocgerg]

Problem is he's not saying that "the point that 20 Hz is the lowest frequency needed in order to have a great subwoofer"; so until you just said that, I had no idea what he's been on about. Let's see if the original thread direction changes.

[HuskerOmaha]

Guys - Yesterday, Spyboy posted a new thread. It's an interesting conversation to have.

I think the basics behind the thread is Rythmik Audio has established a baseline for the output at 20 Hz for their subwoofers.

The response on that forum has been to make fun of Spyboy for posting it.

I believe that both Spyboy and Rythmik are making the point that 20 Hz is the lowest frequency needed in order to have a great subwoofer.

Archea has made much the same point with his captivators here.

This is not my agreeing with the premise (I think, for our subs, 16 Hz is the number), but it is worth discussing without abusing the OP.

The thread can be found here:

http://www.avsforum.com/avs-vb/showthread.php?t=1380572

Spyboy - feel free to join us here for this discussion.

It is an interesting discussion and probably has merit. But for those capable sub systems, since sound designers and mixers in films have purposely put infrasonics and <20hz in their material, I guess I would want a system that is able to reproduce such material.

[craigsub]

Problem is he's not saying that "the point that 20 Hz is the lowest frequency needed in order to have a great subwoofer"; so until you just said that, I had no idea what he's been on about. Let's see if the original thread direction changes.

Understood, but it's not a "problem". All someone had to do was ask if that was what he meant.

Something like "Spyboy, is Rythmik making the point that 20 Hz extension the primary design goal for a proper subwoofer?"

[craigsub]

It is an interesting discussion and probably has merit. But for those capable sub systems, since sound designers and mixers in films have purposely put infrasonics and <20hz in their material, I guess I would want a system that is able to reproduce such material.

Greg - An interesting test would be to take a subwoofer system in a room like MK Theater's. He is basically flat to 5 Hz now.

Have a group of listeners audition the same movie tracks under blind conditions. These movie tracks should have plenty of bass in the 5 to 40 Hz range.

In a random order, they do a 15-30 minute audition of the same tracks. The four scenarios would be:

1. Highpassed at 20 Hz
2. Highpassed at 15 Hz
3. Highpassed at 10 Hz
4. No highpass

The listeners then post impressions of each subwoofer package before knowing which was which.

A study like this would provide meaningful information as to the importance of the listening experience.

[sbdman]

It is an interesting discussion and probably has merit. But for those capable sub systems, since sound designers and mixers in films have purposely put infrasonics and <20hz in their material, I guess I would want a system that is able to reproduce such material.

This idea has been heavily debated, and with the accepted idea that 20 Hz is the lowest point of human hearing, seems to be a "bedrock." I agree that the better mixers introduce it, but probably more of a physical effect than hearing.

The obvious contenders to the accepted rock bottom end, have an experience that are getting out of audible senses arena and into the tactile/pressure area that MK puts it so well as that underwater feeling. There seems to be an electrical charge to the air as well - clothes, hair leather seats seem to be connected to the sound like they're caught in the waves of the ocean.

I'd like to hear Bosso's setup, since he reports that applying a very low HPF in scenes like Black Hawk Down, Irene scene have a noticeable difference when you cut off the single digits area, but somehow he just seems too theoretical to believe. I'll never be able to purchase that level of system, or attend that experience, so just pondering.

A lot of fun are air pressure effects felt by your chest which seem to be affected between outside and inside your lungs, but I think this is more in the higher "slam" region.

[HuskerOmaha]

Yeah I'll agree with that-the pressure or waves flowing over you feeling.

I was trying to go back and see what the barrel roll on FOTP actually was....maybe that is actually around 30hz?

But, the pods emerging and ground imploding, that feels so much more visceral with the 8 MFWs because of the sheer output which I'm sure is bringing up the low end purely by a numbers standpoint, making it more alive, seems to be in the 10-20hz range from looking at the avsforum master bass list and attached spectrum pictures.

I think most people would be perfectly fine with a great setup achieving solid output to 20hz.

[HuskerOmaha]

Greg - An interesting test would be to take a subwoofer system in a room like MK Theater's. He is basically flat to 5 Hz now.

Have a group of listeners audition the same movie tracks under blind conditions. These movie tracks should have plenty of bass in the 5 to 40 Hz range.

In a random order, they do a 15-30 minute audition of the same tracks. The four scenarios would be:

1. Highpassed at 20 Hz
2. Highpassed at 15 Hz
3. Highpassed at 10 Hz
4. No highpass

The listeners then post impressions of each subwoofer package before knowing which was which.

A study like this would provide meaningful information as to the importance of the listening experience.

Might be able to do this with the MFWs and J river. Mojave?

[Mktheater]

The low end, awesome topic as always. The problem here is that not many have experienced 5 hz at reference and louder. I just demoed to a member who has high output to 20hz covered.

I showed him the difference between flat to 5 hz and flat to 10hz and the flat to 10hz was 5 DBS louder overall.

I did not filter any low end out from the 10hz so you still had 5 hz in there. He said with it flat to 5 hz you cloud really feel the low end more but the Midbass is lacking compared to flat to 10hz(uneq'd).

I told him what I I turn it up 5 DBS more and he said flat to 5 hz sound better any day. So I turned it up 5 DBS and te Midbass came back but now the low end was scary!

The bottom line is not 20hz at all. Yes you get awesome perceived low end with that huge Midbass but once you make it flat to 5 hz and then turn it up you will get that Midbass back but now the low end is as strong! BTW, you need lots of headroom to do this and it is fun to show the differences.

I always describe it as underwater but I can also say it just starts feeling weird like the build up of a lightning storm coming. It does not last long but the extra pressure actually seals the doors shut and people always have a hard time opening them. They tell me something is blocking the door and I laugh.

[craigsub]

MK ... Your test as described follows what is pretty normal ... Speaking in relative terms for SPL ...

At "0" dB, the listener thought the tactile was there, but midbass lacking

At plus 5 dB, it sounded better

At plus 10 dB, the whole system came to life

Is this a correct summary?

[craigsub]

Might be able to do this with the MFWs and J river. Mojave?

That would also be interesting. Too bad you don't have a pair of SS-18.2's and a Marathon 5050 amp. :biglaugh:

[tesseract]

I like having the ability to reproduce the 16 Hz content in my Steely Dan recordings.

I wonder if there is a list of music that contains subsonics?

[HuskerOmaha]

That would also be interesting. Too bad you don't have a pair of SS-18.2's and a Marathon 5050 amp. :biglaugh:

Yeah, too bad I dont know where I can purchase such a setup.:peeping:

[Mktheater]

Here is what I meant. Without Eq I am plus or minus 5 DBS from 10-100 hz. I ran the Tron scenes 10 DBS hot or test tone calibrated to 85 DBS. We played Tron at reference and the low end was there but most of the time the 20-100hz was so powerful it masked the low stuff. I EQ'd the 20-100hz content down so I can be flat to 5 hz and when I measured the calibration the test tone was now 80dbs. So I brought down the upper frequencies but the lower frequencies were the same. Listening like this had much more tactile and visceral low end effects that were much more pronounced but the Midbass slam was gone or much lower subjectively. So I turned it back up to a test tone of 85 DBS and BAM! The Midbass was slamming but now that low end was scary! Of course this means I was running Tron flat to 5 hz 10dbs over Reference but I bet most are used to this exagerrated Midbass or 20-100hz. Again you need lots of headroom to do this. I hope this clarifies things!

[nube]

Greg - An interesting test would be to take a subwoofer system in a room like MK Theater's. He is basically flat to 5 Hz now.

Have a group of listeners audition the same movie tracks under blind conditions. These movie tracks should have plenty of bass in the 5 to 40 Hz range.

In a random order, they do a 15-30 minute audition of the same tracks. The four scenarios would be:

1. Highpassed at 20 Hz
2. Highpassed at 15 Hz
3. Highpassed at 10 Hz
4. No highpass

The listeners then post impressions of each subwoofer package before knowing which was which.

A study like this would provide meaningful information as to the importance of the listening experience.

I think bossobass has repeatedly noted doing this exact type of blind testing multiple times, specifically with regard to the intentional inclusion of < 20hz content in movies and music, and his findings are always that audiences prefer the no HPF experience to the HPF experience. Since he has one of the best ULF reproduction systems in the world (purely conjecture, but I'm hard-pressed to find better), I'd say he's already made the case for us.

With regards to Spyboy's thread, it was and still is unclear what he was trying to say, or why he was trying to say it. Until he clarifies, it may be hasty to assume one way or the other.

With regards to 20hz being the low threshold for human hearing, that is a popular myth. Scientists have been testing this since Fletcher Munson's 1933 Equal Loudness Curves (which have subsequently been updated in 1956, for anyone who cares). I posted just a minor amount of the scientific research regarding < 20hz human hearing on AVS here:

http://www.avsforum.com/avs-vb/showt...8#post21362228
and
http://www.avsforum.com/avs-vb/showt...1#post21365081

Granted, I wasn't nice about it, but the guy I responded to is acting like an ignorant douche. That notwithstanding, the scientific research stands on its own merit. I highly recommend reading it.