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Daveis 26th August 2007 01:32 AM

10-25 hz, is it necessary for HT or Music?
Ok, I have this friend... let's call him Joel Ahrens.

Now Joel has 2 subwoofers stacked on top of each other. Both are 10-12" subs. One of them is a MK brand sub. He uses the system for both home theater and music. As far as I can tell both subs are fed the same under 80hz signa from his Rotel multi-channel preamp/processor.

Now I keep telling him of the joy of DIY speaker building. And he scoffs at the concept.

He says he'd consider a DIY sub if it was 18" and could hit 10hz. He says he'd use it in ADDITION to his current 2 subs.

Ok, so how silly is Joel being? He says if I build him an 18" sub that can hit 15hz he'd be all over it.

So is there an 18" driver that can comfortably hit 10hz and costs less than $1000. Also, is there ANY real movie or music content down that low?

ak_47_boy 26th August 2007 02:29 AM

You will be able to get 15hz with a 18". A regular box is never going to do it though. I suggest building a resonant pipe subwoofer tuned at 15hz. Or a horn. Both are going to be huge.

GM 26th August 2007 03:01 AM


Well, you don't say at what SPL and you quote both 10 and 15 Hz, but here's some info to mull over and while he chose 14 Hz, some will be good to 10 Hz, especially the Aura 1808:

Yes to both, though there's little in recorded music that I'm aware of:


Daveis 26th August 2007 03:50 AM

Anything from Dayton or Peerless or TC Sounds that can achieve sub 20hz bass? I see the Peerless XXLS line has some passive radiators that will go down to 18hz.

Can you ever get useful base below Fs even with tuned lines?

As for SPL, he likes it loud.. but I'd say 100db is plenty loud. I'd prefer under 90db since I watch movies frequently over at his place.

Saturnus 26th August 2007 07:43 AM

I'm sorry Daveis but you wont be able to hear sub 20hz. And even at 20hz it will take 120db for you to even start hearing it as that's the threshold of human hearing.

For normal music there is practically nothing lower the low E string on an upright bass which is 41hz. Very few mainly classical works will have organs or even live recording of canon fire going lower than that.

The need for subbass in home audio has grown out of the mistake of trying to recreate earthquake-like tremors in home theaters.

There's a couple of things people seem to forget though, it takes enormous sound pressures for frequencies below 40hz to be even audible and that human hearing is adaptive in the sense that if the harmonic overtones off the base frequency is reproduced correctly then we will hear and feel the base frequency even if it's not there.

So in order to answer your question, no, 10-25hz is absolute not necessary for HT or music. If you absolute want the tremors then buy a bass shaker instead.

Daveis 26th August 2007 05:21 PM

I agree for music under 40hz doesn't do anything for me.

My buddy loves his home theater and likes hearing the big monster thuds and special effects.

I mentioned a couch bass shaker which I think he'd love.

If I compromise and just try to achieve flat to 20hz. I think he'd go for that. What is the best (low distortion, output to 100db) bass driver in the 20-40 hz range?

Adire Audio is gone. TC Sounds is no longer going to sell to DIY from what it sounds like. ALthough I could pick up a TC-2000/TC-3000 at the last minute for a bit longer. The Peerless XXLS and Scanspeak 10" Revelator might work. And then there's the wonderful Dayton 12"/15" reference drivers.

My buddy just talks about BagEnd infra subs. Is there any DIY effort that could equal or top that? I notice they say they operate below resonance. Does that work well? I've heard various contradicting things about the Linwitz Bass transform.

From their site...

The Bag End INFRASUB-18 is a self powered subwoofer system employing a direct radiating 18" cone loudspeaker in a sealed enclosure and a 400 Watt power amplifier mounted to an aluminum plate on the back of the enclosure. The amplifier also includes a built in INFRA dual integrator providing a flat acoustical response down to 8 Hertz, well below the audible range of human hearing.

The INFRA driver is operated below resonance and flattened with an electrical boosting circuit, the INFRA dual integrator. Below resonance the INFRA system exhibits predictable, uniform response and reproduces each note with the same emphasis, reducing the influence of the resonances found in conventional above resonance bass systems.

By extending the frequency response down a full octave below what is considered to be the lowest musical note, low C on a pipe organ (16 Hz), we improve the phase response and reduce the delay throughout the entire audible bass range.

But they go on to say you can't feel it and its not audible.
So what's the point? I have to conclude that below 20hz is just not useful even for home theatre.

While the INFRASUB-18 will reproduce 8 Hz, it is not audible nor does it have enough acoustical power for you to feel it.

Daveis 26th August 2007 06:58 PM

Ok, was just following Zaph's information on low Xmax woofers.

I have experience with the 12" Dayton RS sub and have listened to the other Dayton woofers.

You are sacrificing musicality to some degree to get 20-40hz versus a good large woofer.

Can anyone recommend a woofer that has excellent bass output F3=20hz and low distortion up to 100hz?

Would the Scanspeak 10" revelator woofer do that?

Or would I be better of looking at Peerless XXLS, Aura, Dayton, TCSounds?

RobWells 26th August 2007 07:07 PM

For music I'd say flat to ~25Hz is fine - I've got plenty of electronic artists in my collection with synth bass down to at least 30Hz (I have an RTA inline all the time so can see where the bass is at)

For dvd's ideally I'd want extension down to ~10Hz. I used to use 3 15" tempests, each in a sealed 200L enclosure flat to 12Hz. Now I use 2 labhorns that are eq'd flat to 20Hz. The extra extension of the tempests made a difference and it's only lack of space right now that has stopped me putting in some 'big stuff' to give me big output down to less than 10Hz.

Even if you can't hear a 10Hz wave in your room you'll still feel it:D

For your friend, I'd suggest a ported 18" driver tuned to ~12Hz in a big box.

As he's going to run other subs above this one maybe something interesting could be done with a bandpass box, tuned to give output in the 12Hz - 25Hz region. Have a look at Dan Wiggins of Adire's suggestion here


myhrrhleine 26th August 2007 07:41 PM


the phase response is determined by the bass response.
lower F3 means more linear phase.
A speaker designed for a lower F3 will often (not always) distort less at higher frequencies.

Daveis 26th August 2007 08:07 PM


Originally posted by RobWells

For your friend, I'd suggest a ported 18" driver tuned to ~12Hz in a big box.

As he's going to run other subs above this one maybe something interesting could be done with a bandpass box, tuned to give output in the 12Hz - 25Hz region. Have a look at Dan Wiggins of Adire's suggestion here


So, what 18" driver would be up to the task? Every big driver (like the TCSounds stuff) has an Fs=23. My own Dayton 12" has an Fs=23. Does this mean I need to find an 18" driver with an Fs that's 15hz. I'm not see any (available to DIY) with specs like that.

Dan Wiggins idea (which sounds cool) requires 14 cu feet of box.

What is the smallest box/driver you could build on average and still hit 20hz flat?

Should I be looking at Pro/PA drivers from Pioneer, JBL, etc?

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