Bag End Infrasub, the latest subwoofer scam?

[SigbergAudio]

Indeed, hardly new.

Way Down Deep II

In Part II of the perhaps most ambitious report on subwoofers ever to appear in print, Keith Yates gives you the lowdown on four more contenders, from one that uses a water-filled membrane in its design to a model popular for producing gut-wrenching rumbles on theme-park rides. Details on the...

www.soundandvision.com

IIRC their drive units only have about half the throw of the current SOTA “pro” devices.

Nice graphs in that article (And I didn't know Keith Yates used to do reviews), but they don't specify the distance. I guess we can assume 1 meter?

 

[SigbergAudio]

By skimming the video I'm not sure if there is anything in the somewhat complicated explanation beyond being a sealed enclosure where they use DSP to amplify (and limit) the low-end? Which they in the video are comparing to a ported system? Nothing wrong with that, but also not quite as unique as presented? Or am I missing something?

 

[Waxx]

I once had a diy sub that went very low (f3 of 23Hz, f10 of 16) but changed the design to a 30Hz (F3) tuned sub, because that low there is only rumble. Below 30Hz is only needed for HT in my opinion, and even the 16Hz organ note (that is rare) can be heared with that 30Hz sub, as the first overtones (32 and 64hz) are there and your brain fools you by recreating the fundamental. So no need to go that low. Nowadays with dsp I even filter out everything below 25Hz (8th order filter), also to avoid vinyl record rumble (yes i do listen to vinyl from time to time).

 

[norman bates]

Yea, a ported (and tuned at) 27hz or the systems f3 (theoretical anechoic) was plenty low for me.

I hunted through my cd's for bass under 60hz.
Not many I have except some William orbit mixed "ray of light" from madonna.

Even morpheus's knee through the floor in the first matrix movie was centered near 60hz (according to the DoD spectrum analyzer I had at the time).

To me, below 60hz is rumble, or shaking the dust off the ceiling notes.
I believe it can set the tone for action/horror movies.

But my 80's / mid 90's rap doesn't need anything below 60hz for me.


I know the first track on yellow's CD toy, "frau tonium" gets rumbly low according to a friend with infinity kappa 9's....

 

[Waxx]

There are many music styles that go way below that, even classical does often. But rarely below 30Hz, and most even not below 40 (especially older music). A lot of the music i listen to is quiet bass heavy and needs a good 30Hz to shine. But it's mostly reggae or electronic music. But if you only listen to rock or classic pop, 40Hz and above will do the job.

 

[Titurel]

One might be surprised how much low-sonic material there is in fairly conventional TV programming. For instance, the theme music for Masterpiece Theatre's 2016 series "Victoria" contains sub 30Hz organ fundamentals, which evoke memories of the cathedral ambience during the queen's coronation. As has been mentioned by others, a large enclosed space is difficult to portray without low, sub, and (even) infra sonics.

My present system is flat to 20Hz with a steep cutoff below. Organ music sounds like organ and large spaces are realistically portrayed.

However, were I a frequent visitor to the Marvel Universe or enjoyed humming along with test discs, I'd probably dial in a steeper filter starting an octave sooner. This is not because I fear intended output below 40Hz. It's the unintended output that angers neighbors and has you reconing your woofers.

 

[egellings]

This uses 14 minutes of AI CGI to describe a below resonance operated sealed subwoofer with a correction EQ and excursion limiter. You have to buy their "Integrator" to do worse (only +6 dB shelv) what any 10$ DSP would do *facepalm*‍

Could have just posted free field frequency response & CEA-2010 graphs of the thing and we would have known everything we needed to know. I doubt we will ever see either.

Who can hear 8Hz? No point in it. Get a massage chair for that.

 

[levimax]

The threashold of hearing at 8 Hz is 103 dB. A small enclosure and driver as described may create a very limited amout of distorted 8 Hz signal but it is going to have many orders of magnitude less energy than what is required to be heard / sensed. The only audible result may be be intermodulation distortion. The presentation carefully stays scientifically correct but without any practicle context 8 Hz from a small enclosure and driver is just a bogus claim to confuse people.

 

[kemmler3D]

There are many music styles that go way below that, even classical does often. But rarely below 30Hz, and most even not below 40 (especially older music). A lot of the music i listen to is quiet bass heavy and needs a good 30Hz to shine. But it's mostly reggae or electronic music. But if you only listen to rock or classic pop, 40Hz and above will do the job.

Tonal content is not the only consideration, transients (if not highpassed) will technically be full-spectrum, (so anything with drums) and ambience can have an arbitrary spectrum.

 

[Titurel]

The threashold of hearing at 8 Hz is 103 dB.

You may be guilty here of comparing sensory apples to bagels. 8Hz can be felt at much lower signal levels than it can be heard. There is no need for infra tones to be perceived (exclusively) aurally for them to be telling in a performance. As has been mentioned, low sonics and sub-sonic can induce feelings of discomfort, dread, or awe, while not being perceived (heard) as sound. Why do you think church organs frequently have 32' registers, a few even have 64s? Resultants can produce even lower pitches. E.g., 32'C and G played simultaneously - Awesome! - we hear C and G and feel the sub-octave resultant pitch as it rattles our thoraxes.

 

[levimax]

You may be guilty here of comparing sensory apples to bagels. 8Hz can be felt at much lower signal levels than it can be heard. There is no need for infra tones to be perceived (exclusively) aurally for them to be telling in a performance. As has been mentioned, low sonics and sub-sonic can induce feelings of discomfort, dread, or awe, while not being perceived (heard) as sound. Why do you think church organs frequently have 32' registers, a few even have 64s? Resultants can produce even lower pitches. E.g., 32'C and G played simultaneously - Awesome! - we hear C and G and feel the sub-octave resultant pitch as it rattles our thoraxes.

64 ft pipes are ~8.2 Hz with 120 dB output, you need a huge amount of SPL for 8 Hz to be perceived in any way. The amount of 8 Hz energy made by small subs amounts to practically nothing. I am not saying it can't or should not be done, but it is a scam claiming a small sub can do anything useful at 8 Hz.

 

[KL....]

64 ft pipes are ~8.2 Hz with 120 dB output, you need a huge amount of SPL for 8 Hz to be perceived in any way. The amount of 8 Hz energy made by small subs amounts to practically nothing. I am not saying it can't or should not be done, but it is a scam claiming a small sub can do anything useful at 8 Hz.

Thank you, @levimax, have you tested/measured the Bag End InfraSub? Note that @Vladimir Filevski has suggested/indicated otherwise (ie not a scam) and has built it and it would appear measured the build.

• Further note, as 2 threads have been merged, that I asked for the Title of this thread 'The latest subwoofer scam' to be changed to 'Bag End InfraSub'.... do you have any objection/s?

It is not a subwoofer scam! You got it all wrong.
It is not "only +6 dB shelv"! A single integrator has 6 dB per octave slope, so for equalizing a second-order sealed enclosure, two integrators are needed, producing 12 dB per octave slope. You can equalize it to 1 Hz if you want, but for practical reasons Bag End subwoofers are limited to 8 Hz. This type of subwoofer is patented by Edward Long and Ronald Wickersham and is licensed to Bag End company.
I built this type of subwoofer some 20 years ago, with 18" RCF pro driver - it works as advertised by Bag End company. I limited it to 15 Hz.

 

[ElJaimito]

I built this type of subwoofer some 20 years ago, with 18" RCF pro driver - it works as advertised by Bag End company. I limited it to 15 Hz.

I built some in 199?3?4? based on a circuit in the magazine ETI (UK). There's also two designs available (for own use, Bag End for some reason managed to get patents on something so obvious, which may still be in force) here:

P48 Sub-Woofer Controller (Rev-A)

ESP Project Pages - Electronically Assisted Subwoofer (EAS) - If you have tried to get a sub to sound right (and go low enough), you already know that it is not easy. Well, now it is :-)

sound-au.com

The concept is sound, the result is near ideal bass performance down to sub-20Hz for precision uses (such as recording studios). No overhang, no flappy bass. I still use the one I built in the '90s and will be building a new system fairly soon for new woofers. Of course, there's a trade off: ~ 1kW of amps required to match 96dB+ levels @3m with reserve power, and drivers that can handle that transient power. Currently I blew my elderly Yamaha power amp It's strange the technique is not better known. Or perhaps (kW) not...

 

[ElJaimito]

64 ft pipes are ~8.2 Hz with 120 dB output, you need a huge amount of SPL for 8 Hz to be perceived in any way. The amount of 8 Hz energy made by small subs amounts to practically nothing. I am not saying it can't or should not be done, but it is a scam claiming a small sub can do anything useful at 8 Hz.

Actually not so. But it is a very bad idea trying to reproduce such frequencies, and they have no musical value. Just property damage. A sealed equalised sub has no lower limit in principle, but it is limited by woofer displacement capacity and power handling (plus availability of the input power). I would not go below 18Hz to avoid structural damage.

 

[EJ3]

I personally think the bottom octave is more important than the top, because (1) EVERYONE can hear bass, but not everyone can hear the top octave, and (2) there is simply more music down there. This doesn't mean I am willing to sacrifice the top end though! It is easy to choose a tweeter that goes up to 20kHz, and any speaker that does not do at least that IMO isn't worth considering.

But ultimately it depends on you - do you have hearing loss? Do you regularly listen to music with extension up to 20kHz? You can test this yourself by getting REW to play a test tone at standard listening level. Start at 1kHz and adjust the volume until it feels subjectively loud. For a sanity check, put a mic next to you and use REW's RTA. This is to confirm that your speaker is actually producing sound. Then 5kHz, 10kHz, 15kHz. When you get to 15kHz, increase the tone by 1kHz increments. At some point you will stop hearing it. I can barely hear a 16kHz test tone, which is good for my age (54). Needless to say, you will need a speaker that is flat to 20kHz to conduct this test.

There are many that can't hear above 15K. Maybe more over 30 year old's that can't than that can. If you get the volume high enough at 16K, I can barely sense it.
So, for me, realisticly, if it gets solidly to 15 K, it's fine.
And that was, at one time, a worthy thing by many. Thigs above 16K, I can only see if I am using a measuring mike to graph it.
Of course, since I share my stereo when people come over, I want 20K capability.
But for me (and many) there really is no purpose for it any more.
But I do hear something below 20, as to how far below, I don't know, since I do not have the capability to (in subs) to go lower than 20 Hz.

 

[Chrispy]

There are many that can't hear above 15K. Maybe more over 30 year old's that can't than that can. If you get the volume high enough at 16K, I can barely sense it.
So, for me, realisticly, if it gets solidly to 15 K, it's fine.
And that was, at one time, a worthy thing by many. Thigs above 16K, I can only see if I am using a measuring mike to graph it.
Of course, since I share my stereo when people come over, I want 20K capability.
But for me (and many) there really is no purpose for it any more.
But I do hear something below 20, as to how far below, I don't know, since I do not have the capability to (in subs) to go lower than 20 Hz.

You have some sort of hard pass on your subs below 20?

 

[EngineerNate]

My room pressurizes around 20ish hz and I get yelled at by SWMBO.

 

[Blockader]

Why do you "need" 8hz extension and at what relative point to the general frequency response especially after eq to get there?

The lowest note on a church organ is 8Hz, and at sufficient volume, you can actually feel it. Because it's the lowest note the instrument produces, it's often considered the benchmark for subwoofer capability.

 

[Chrispy]

The lowest note on a church organ is 8Hz, and at sufficient volume, you can actually feel it. Because it's the lowest note the instrument produces, it's often considered the benchmark for subwoofer capability.

A few organs with special pipes? Got an example of a recording of one?

 

[Titurel]

A few organs with special pipes? Got an example of a recording of one?

Answering your first question: it is not (just) a few organs nor special pipes.

Pairs of pipes, played together create "resultant" pitches. A resultant can be the product of a stop, that couples the pipes (electrically or mechanically), or by a player actually playing them simultaneously. Even modest sized organs with 16' pipes can readily produce 32' pitches; likewise, moderately large to very large organs with 32' stops can produce 64' pitches (down to 8Hz). Last time I checked, there were only 2 actual, full-length 64' stops equipped organs, which I suppose would qualify them as special, but as to 8Hz response they are not.*

I have no interest in finding a sub 16Hz recording, but I have little doubt they exist, unless CD mastering hardware or software precludes such. That may the correct or more relevant question.

* If you wanted 4Hz, these 2 organs are the best equipped to give it you.