Looking to run a true 5HZ signal to my Sub woofers but think my anthem receiver will Bottle neck this.

[Allen Vos]

If this is what you want to pursue you should. Whether it works out or not, this is a hobby and the pursuit and journey is the point.

There are clearly some here who cannot get out of their own way and forcing their own preference or agenda into every subject. I mostly just ignore them at this point. They also post as though they have any authority over your actual experience or enjoyment of whatever it is that you do hear or feel. There is value in the science and objectivist analysis of things, but ultimately this is a hobby that boils down to your personaly sensory perception of things and whether or not you enjoy it or not.

I am glad I'm not the only one seeing this.........Spelling it out a couple times wasn't enough, so does it need to be typed out in all caps next? I feel like we are all stuck on repeat here.

I fix cars for a living, and if I used this level of circular logic with my customers, they’d look at me like I had three heads and take their keys back immediately."

 

[m. zillch]

This original release's square wave also shows some nasty clipping [depicted in red below] at least in this version I just measured:

 

[m. zillch]

forcing their own preference or agenda into every subject.

I'm not "forcing" anyone to do anything, but I have a right to express my position, just like everyone else, and I often explain how I got there.

 

[TLS Guy]

Just to clarify, since I am starting this build from scratch, I want to ensure the system is physically capable of extending down to 5 Hz. I know most LFE tracks rarely drop below 10–12 Hz, but I want that ultra-low headroom built into the design from day one.
I am completely open to your suggestion of increasing the enclosure size. Because these boxes haven't been built yet, going larger will only cost me an extra sheet or two of the 3/4" Baltic Birch veneer plywood I plan to use.

Enclosure Volume & Driver Mechanics
While I noticed the higher output gains offered by the 8.2 ft³ box, I also see that it increases driver excursion. I am trying to determine how critical this is for a 5Hz-capable system. Moving from the 6.2 ft³ box to the 8.2 ft³ box bumps the Xmax by 3.5mm—bringing it to 26.5mm, which is getting uncomfortably close to the driver's 29mm limit. That said, I appreciate that the larger air volume is easier on the driver, creates less voice coil heat under heavy loads, and yields a deeper, more natural bass.
On this note, I have two specific technical questions:

1. Xmax Specifications: Can you clarify how you calculated a 34mm Xmax, compared to the manufacturer’s listed 29mm spec? I am trying to understand that discrepancy.
2. Mid-Bass Impact: How will transitioning from a 6.2 ft³ to an 8.2 ft³ enclosure affect the "punchy" mid-bass frequencies from 40 Hz and up? Will the punch increase, decrease, or remain relatively unchanged?

Cabinet Dimensions & Construction
For construction, my original plan was a 24" x 24" x 24" cube featuring a double-thick front baffle, a central window brace, extensive interlocking bracing throughout, and a dedicated support ring for the driver basket. I will absolutely post build photos once sawdust starts flying!
If I move to the 8.2 ft³ net volume, I will spec the gross internal volume to 8.6 ft³ to account for the 0.4 ft³ displacement of the driver and bracing.

• A 26" x 26" x 26" cube achieves this, but I am wondering if it would be structurally superior to keep the face at 24" x 24" and extend the depth to 31" instead?
• Changing the depth to 31" would actually fit significantly better in my dedicated room layout.

Current System Layout
For context, here is the rest of the audio chain I am integrating these into:

• Receiver: Anthem MRX 1140
• Front L/R: Paradigm Premier 8000F
• Center: Paradigm Premier 600C
• Side Surrounds: Paradigm Monitor 7 v5
• Rear Surrounds: Paradigm Monitor 11
• Atmos: 4x Paradigm Pro PR-80R (In-Ceiling)
• DSP: MiniDSP Flex HTx
• Subwoofers: 4x Sealed FTW-21 drivers
• Amplification: CVR D1004 rack amplifier (capable of 1700W RMS @ 4 ohms, dialed back to 1200W)

OK, we need to get back to the physics of the situation. We have to follow the rules of physics as dictated by natures physical laws.

The first point I would make is that the least promising way of loading a driver is a sealed box. You are fighting natures laws, and not working with them in any way that assists the driver to perform well. Ported enclosures, pipes and horns harness natures laws, which if followed enhance the design enormously. The one advantage to sealed is that it substantially reduces enclosure volume. But the driver is on its own so to speak. However, the restoring force is the spring of the compressed air in the enclosure. Essentially the box volume is determined by driver limits. So whether the xmax, is 29 or 34 is of no consequence as the driver is not reaching xmax in these designs and are of no consequence to the FR.

Now, the free air resonance of any driver effectively sets is useable low frequency limit +/- a few Hertz. If you push it below Fs distortion rises rapidly and you also start to get frequency doubling as the cone starts to break up from the force of the VC. So that is why every engineer who knows their craft high passes around F3. The models I gave you are correct and you can see the FR starting to go horizontal below F3.

So, whatever any body else tells you on the net, the driver needs to be high passed for its protection and stop distortion rising to absurd amounts.

So it is fundamental to the design of a sealed alignment that you high pass around F3, and certainly where a driver gets close to xmax.

There is no way you can escape these laws of physics and good design practice. If you do, you will not get the results you want and risk driver damage.

I have been doing this for a very long time and my mentors were some of the most famous in the history of audio and I stayed in touch with some until their deaths.

I have given you the correct advice and it is nonsense and BAD practice to pursue infrasonic frequencies with a sealed design. If you do, you stand a good chance of being out a lot of money by destroying drivers. All drivers are susceptible to damage if the design and physics are not correct.

Lastly this obsession with low frequency reproduction has been on the whole harmful, as it has taken funds away from where money would be much better spent in regions of the FR that a far more important to good and realistic reproduction.

 

[dolynick]

I'm not "forcing" anyone to do anything, but I have a right to express my position, just like everyone else, and I often explain how I got there.

Your inststence that any of your graphs overrule my own experience in my own house in my particualr setup is the issue. No one is disputing the science behind the graphs. But I can go downstairs and in 2 minutes have a 10Hz tone playing through the system and listen to the room shudder and creak. I may have to turn it up a little to make it more encompassing, sure. My system is not designed to emphasize that range. But for you to sit there and post replies suggesting that I'm not hearing or experiencing anything in that range (and thus getting some sort of experience from it) or that the OP shouldn't pursue his project (I'm sure he's well aware that there isn't a lot of content down there in the first place, that's not really the point) is so overbearingly arrogant that it makes your post useless and pointless. The information was good. You could have left it at that.

 

[m. zillch]

that the OP shouldn't pursue his project

On the contrary. I want the OP to make an infrasonic capable system so he can properly experience the frequency sweep in my test video, to then fully comprehend what frequencies do what.
------------------------------

Hearing bass is fun for me too.
Feeling bass is fun for me too.
Getting the best possible system (which is within my budget and room constraints) to do this is one of my goals. [Removing unproductive and detrimental content, such as ultrasonic and infrasonic material, is also a goal.]
But what eludes me, personally—that's just me, not that I'm forcing my view on anyone else—is why making one's dishware rattle, yet not hearing nor feeling the infrasound that causes it, would be seen as "beneficial", like occurs here in this short video I already posted:

Interestingly note the poster of this very video in the comments describes it in the same way that I would with a single word: "Annoying", i.e. not beneficial. [Yet my call is his system or content is artificially EQ'd to induce this (or perhaps it is from a recording of a warped LP causing the stylus to generate infrasound as it bobs up and down on the disc to negotiate the warp) in which case he needs to learn about using an HPF to remove this detrimental (from his and my perspective) content.]
. . . but I see that they certainly sometimes market such sympathetic rattles as a goal some people might pursue, so I accept it's just a thing that I don't personally get, but that's just me:

"FTW-21 – For the Win!
Imagine if you can, every picture, vase, dish and window in your home rattling uncontrollably as air pressure begins to build in your theater room. That’s what will happen if you get the FTW-21."

 

[ski2xblack]

The problem with seismic infrasonic extension is that it causes seismic results.

This one time I was visiting the home of a fellow forum member so he could show off his new sub setup, which entailed multiple 18" AE subs and several kilowatts on tap. He spent a small fortune on it.

As I sat in the dimly lit home theatre room he slowly advanced the volume. Increasingly, every knick knack on every shelf in the house began to rattle. Then the picture frames began to rattle against the walls, and the doors within their door frames. I knew I was in trouble when the vitreous fluid in my eyeballs began to sympathetically vibrate. It turns out the average sized eyeball's resonant freq is about 18hz, in case anyone is wondering.

The experience to this point was disorienting and highly uncomfortable, nauseating even. But there's more! He continued to advance the volume. As I sat there, through blurred vision, I noticed bits of plaster and dust fall from the ceiling. The walls themselves were now beginning to bow and flex.

Terror gripped me and I dashed for the door. No sooner had I launched myself onto the front lawn when the entire structure of the house gave way completely, imploding as though through controlled demolition. All that remained was a choking cloud of dust and pile of rubble filling the foundation.

True story.*















* Partially true, at least.
-Your eyeballs really do resonate at 18hz or so.
-The listening experience was truly horrid, akin to being in an earthquake.
-I may have slightly embellished the implosion part, but I couldn't get out of there fast enough.