RBH Sound 21" Monster 4kwatt Sub First to Meet our Maximus Bassaholic Rating!

[shadyJ]

Why would you place all subs in a single spot, tho? Or you mean just within a 1/4 wavelength or ?

If you want the most output, placing them all in one spot ensures that there won't be any phase cancellation. But 1/4 wavelength distance out to be sufficient. Of course, I wouldn't advise anyone placing all the subs in one spot in room.

 

[TLS Guy]

So why can't a ported sub be done that could get you there to infrasonic.? One with a low port tune. The box needs to be bigger. But with that in mind the power requirements are less and as long as the ports can go that low you get the best output vs efficiency especially with power usage.

In fact @TLS Guy your talented and very knowledgeable about modeling and building speakers and subs.

Not asking for a detailed model but can you give us an rough ideas ballpark figure on just how big a box and driver would need to be to get you there into infrasonics without using a ton of power

You really can't reverse engineer like that. You have to have a driver that could actually be built, with measured T/S parameters. If RBH will publish the T/S parameters of that driver, I will tell you exactly.

But the bigger question is: - why this obsession with infrasonic frequencies? I maintain they do not contribute to the pleasure of audio, or AV on the home and actually almost certainly the reverse. They will annoy family members as Gene has pointed out with his family. They might cause structural damage, and probably will to largely American built homes. Even my TLs had enough infrasonic output to give me concerns from my frame built room at our Benedict location. Seriously that was a factor in building a concrete house. As I have said in this thread, we don't even know if it safe to expose humans to infrasonic sound on a regular basis and I strongly suspect it isn't. So just on the doctrine of primum non Nocere, this is a bad idea.

My opinion is that the pursuit of these infrasonic frequencies in home audio and HT is just plain daft, and more than likely unsafe.

 

[highfigh]

You really can't reverse engineer like that. You have to have a driver that could actually be built, with measured T/S parameters. If RBH will publish the T/S parameters of that driver, I will tell you exactly.

But the bigger question is: - why this obsession with infrasonic frequencies? I maintain they do not contribute to the pleasure of audio, or AV on the home and actually almost certainly the reverse. They will annoy family members as Gene has pointed out with his family. They might cause structural damage, and probably will to largely American built homes. Even my TLs had enough infrasonic output to give me concerns from my frame built room at our Benedict location. Seriously that was a factor in building a concrete house. As I have said in this thread, we don't even know if it safe to expose humans to infrasonic sound on a regular basis and I strongly suspect it isn't. So just on the doctrine of primum non Nocere, this is a bad idea.

My opinion is that the pursuit of these infrasonic frequencies in home audio and HT is just plain daft, and more than likely unsafe.

There's no way it would only be family members whop are annoyed since low frequencies are very difficult to block and stop. I often hear car stereos from the major street that's two blocks away from my house and it doesn't matter if every door and window is shut tight, it's coming in.

It seems to be a 'Because we can' goal. Unless someone is dead set on achieving special effects nirvana, there's almost no reason to do this. Maybe recordings with the 64' stops in the pipe organ in Atlantic City are a favorite musical source.

The frequencies from that organ are a great way to show that a speaker system needs at least one subwoofer- I played some of the audio tracks and the lowest notes modulated the midbass and lower midrange pretty badly.

 

[Danzilla31]

You really can't reverse engineer like that. You have to have a driver that could actually be built, with measured T/S parameters. If RBH will publish the T/S parameters of that driver, I will tell you exactly.

But the bigger question is: - why this obsession with infrasonic frequencies? I maintain they do not contribute to the pleasure of audio, or AV on the home and actually almost certainly the reverse. They will annoy family members as Gene has pointed out with his family. They might cause structural damage, and probably will to largely American built homes. Even my TLs had enough infrasonic output to give me concerns from my frame built room at our Benedict location. Seriously that was a factor in building a concrete house. As I have said in this thread, we don't even know if it safe to expose humans to infrasonic sound on a regular basis and I strongly suspect it isn't. So just on the doctrine of primum non Nocere, this is a bad idea.

My opinion is that the pursuit of these infrasonic frequencies in home audio and HT is just plain daft, and more than likely unsafe.

I was just curious how big a box for a ported version would have to be

 

[TLS Guy]

I was just curious how big a box for a ported version would have to be

You will have to stay curious, unless Gene can persuade RBH to publish the T/S parameters. There was a time, sadly now long, long ago, when manufacturers were an open book about information like that. They listen to marketers who just believe as an article of faith, that doing so will loose sales. I know they are wrong about that like nearly everything else. Raymond Cooke of KEF would never have concealed data like that, but would be proud to publish to all. He did. He also published constrictor plans. That is a way to involve customers, build interest and market. Keeping information proprietary I am certain reduces and looses sales, openness achieve the exact opposite. As Peter Walker always said, you get a lot of work done for free!

 

[TLS Guy]

There's no way it would only be family members whop are annoyed since low frequencies are very difficult to block and stop. I often hear car stereos from the major street that's two blocks away from my house and it doesn't matter if every door and window is shut tight, it's coming in.

It seems to be a 'Because we can' goal. Unless someone is dead set on achieving special effects nirvana, there's almost no reason to do this. Maybe recordings with the 64' stops in the pipe organ in Atlantic City are a favorite musical source.

The frequencies from that organ are a great way to show that a speaker system needs at least one subwoofer- I played some of the audio tracks and the lowest notes modulated the midbass and lower midrange pretty badly.

I agree with all that. Obviously a sub or two helps, but you don't have to go extreme. The money put into what happens between 500 Hz and 5 KHz has a far greater impact. So budget needs to be concentrated far more on that range than 40 to 20 Hz. I really think an F3 around 20 Hz is all that is required for optimal results and enjoyment. The rest is just spending money on bragging rights, which is not very useful.

 

[ryanosaur]

I was just curious how big a box for a ported version would have to be

Here is a design for the SI HS24 Driver that Red Five did as a companion to the Devastators/

The Devastator Index

www.avsforum.com

It comes in at just under 20cu.ft net volume with a 12 hz tune.

 

[TLS Guy]

Here is a design for the SI HS24 Driver that Red Five did as a companion to the Devastators/

The Devastator Index

www.avsforum.com

It comes in at just under 20cu.ft net volume with a 12 hz tune.

There you see the issues. That is clearly an extended bass alignment form the curves, and in my view not an optimal alignment. Then you have another problem, either a port with too high a vent velocity or one with a port resonance in the operative frequency range. When you design a really good sub, you have to take a very balanced view. Concentrating on how low you can tune it to lower F3, is not balanced. That leads to sub-optimal alignments, which I fear have plagued this market for some time and still does. Raving on about infrasonic extension will only add to the problem.

 

[Shane Rich]

Hello All,

Great to see all the interest regarding our new subwoofer. I have a few comments regarding some of what has been discussed. This subwoofer is not any more dangerous to own or operate than any other high output sub on the market. The subwoofer has a grill option to protect against accidental or purposeful contact with the driver. Yes, the driver is tremendously powerful, but not to the point of causing some type of bass explosion resulting in destruction of the subwoofer that would potentially cause bodily harm or injury as some have insinuated. There have been hundreds of hours of extreme SPL testing performed with this subwoofer while developing the driver and enclosure. Several drivers and a single test enclosure have sustained minor damage in the process, which resulted in further improvements to the driver and enclosure, but sadly nothing as dramatic as what has been discussed. If the subwoofer was capable of explosive destruction, it would make my job incredibly exciting! Just like car crash testing, it is my job to test this product to the point of failure to find out what the subwoofer's limits are. I can definitively tell you, that is not an easy task to perform with this sub using our 4000W+ capable amplifier. I have yet to burn up a voice coil on this driver even when the subwoofer has been continuously pushed over and over again during extreme testing that an end user of the subwoofer would likely never be able to replicate even if they were purposely trying to burn it up. Also, there are no power handling problems at all using neodymium magnets in this open motor structure . Yes, large ceramic magnets used in a motor structure are capable of dissipating more heat, however, because of the enclosed nature of ceramic motor structures (how they cover the voice coil bellow the top plate all the way to the back plate) , they need to be able to dissipate more heat due to being subjected to more heat from the voice coil. The open motor structure our driver uses does not require substantial heat dissipation by the magnets and is ultimately capable of higher sustained voice coil temperatures (thermal power handling).

Why use a sealed design over a vented design for the subwoofer? Read Matt's explanation posted above. He explains it very well. Sealed subs are inherently more effective at producing extreme low frequency (infrasonic) output in reasonably sized enclosures. For those that are interested in a vented version of the 21" sub, we can produce a vented version of this subwoofer which requires a 19 cubic ft enclosure (Fb=16Hz), but is capable of producing 125dB@20Hz and 113dB@16Hz, passing CEA2010 distortion levels. At 12Hz and below the sealed 21-FS/R has more output in a much more reasonably sized 6 cubic ft enclosure.

Regarding how the 21-FS/R performs/sounds, I look forward (like all of you) to reading Gene's opinions in his review. All I can say from my perspective as the engineer behind the product, is this; I have heard a number of very good subwoofer systems from various manufacturers over the 30 years I have worked in the industry, but as of yet, I have never heard/experienced another subwoofer quite like this.

Shane Rich
Technical Director
RBH Sound

 

[TLS Guy]

Hello All,

Great to see all the interest regarding our new subwoofer. I have a few comments regarding some of what has been discussed. This subwoofer is not any more dangerous to own or operate than any other high output sub on the market. The subwoofer has a grill option to protect against accidental or purposeful contact with the driver. Yes, the driver is tremendously powerful, but not to the point of causing some type of bass explosion resulting in destruction of the subwoofer that would potentially cause bodily harm or injury as some have insinuated. There have been hundreds of hours of extreme SPL testing performed with this subwoofer while developing the driver and enclosure. Several drivers and a single test enclosure have sustained minor damage in the process, which resulted in further improvements to the driver and enclosure, but sadly nothing as dramatic as what has been discussed. If the subwoofer was capable of explosive destruction, it would make my job incredibly exciting! Just like car crash testing, it is my job to test this product to the point of failure to find out what the subwoofer's limits are. I can definitively tell you, that is not an easy task to perform with this sub using our 4000W+ capable amplifier. I have yet to burn up a voice coil on this driver even when the subwoofer has been continuously pushed over and over again in extreme testing that an end user of the subwoofer would never likely be able to replicate even if they were purposely trying to burn it up. Also, there are no power handling problems at all using neodymium magnets in this open motor structure . Yes, large ceramic magnets used in a motor structure are capable of dissipating more heat, however, because of the enclosed nature of ceramic motor structures (how they cover the voice coil bellow the top plate all the way to the back plate) , they need to be able to dissipate more heat due to being subjected to more heat from the voice coil. The open motor structure our driver uses does not require substantial heat dissipation by the magnets and is ultimately capable of higher sustained voice coil temperatures (thermal power handling).
Why use a sealed design over a vented design for the subwoofer? Read Matt's explanation posted above. He explains it very well. Sealed subs are inherently more effective at producing extreme low frequency (infrasonic) output in reasonably sized enclosures. For those that are interested in a vented version of the 21" sub, we can produce a vented version of this subwoofer which requires a 19 cubic ft enclosure (Fb=16Hz), but is capable of producing 125dB@20Hz and 113dB@16Hz, passing CEA2010 distortion levels. At 12Hz and below the sealed 21-FS/R has more output in a much more reasonably sized 6 cubic ft enclosure.

Regarding how the 21-FS/R performs/sounds, I look forward (like all of you) to reading Gene's opinions in his review. All I can say from my perspective as the engineer behind the product, is this; I have heard a number of very good subwoofer systems from various manufacturers over the 30 years I have worked in the industry, but as of yet, I have never heard/experienced another subwoofer like this.

Shane Rich
Technical Director
RBH Sound

I am glad you were aware of the problem an tested for it like I hoped you had. It is interesting to me that you walked right up to the line, and it seems an inch or two over it.

As far as damage to the human body from frequent exposure to infrasonic sound waves, this is still very much I work in progress. However there is enough data to proceed with caution. It seems to bring a different set of problems compared to high spl. acoustic damage to the inner hear and VIII cranial nerve. What is of concern at this time is CNS and cardiovascular damage. CNS damage is easier to explain than cardiovascular damage. But medicine has a long history of turning up the unexpected in search of an explanation. Myself, I have thought for some time there is a level of concern, so I have been moderate with LF outputs. Apart from anything else they have a significant antisocial aspect, and that is well known. At the end of the day we have a lot bigger fish to fry, than infrasonic reproduction. There are far more pressing priorities in need of improvement.

 

[Verdinut]

There's no way it would only be family members whop are annoyed since low frequencies are very difficult to block and stop. I often hear car stereos from the major street that's two blocks away from my house and it doesn't matter if every door and window is shut tight, it's coming in.

It seems to be a 'Because we can' goal. Unless someone is dead set on achieving special effects nirvana, there's almost no reason to do this. Maybe recordings with the 64' stops in the pipe organ in Atlantic City are a favorite musical source.

The frequencies from that organ are a great way to show that a speaker system needs at least one subwoofer- I played some of the audio tracks and the lowest notes modulated the midbass and lower midrange pretty badly.

Not only the frequencies from that organ, but frequencies from all pipe organs that have a true 32 foot pipe with a fundamental frequency of 16 Hz, are actually better suited for enjoying infrasonic sounds.

By the way, the fundamental frequency of the 64' pipe is 8 Hz. Not only the organ in Atlantic city has a 64' pipe. There's one at the Sydney Town Hall in Sydney, South Wales, Australia:

Sydney Town Hall Grand Organ - Wikipedia

en.wikipedia.org

 

[Danzilla31]

Hello All,

Great to see all the interest regarding our new subwoofer. I have a few comments regarding some of what has been discussed. This subwoofer is not any more dangerous to own or operate than any other high output sub on the market. The subwoofer has a grill option to protect against accidental or purposeful contact with the driver. Yes, the driver is tremendously powerful, but not to the point of causing some type of bass explosion resulting in destruction of the subwoofer that would potentially cause bodily harm or injury as some have insinuated. There have been hundreds of hours of extreme SPL testing performed with this subwoofer while developing the driver and enclosure. Several drivers and a single test enclosure have sustained minor damage in the process, which resulted in further improvements to the driver and enclosure, but sadly nothing as dramatic as what has been discussed. If the subwoofer was capable of explosive destruction, it would make my job incredibly exciting! Just like car crash testing, it is my job to test this product to the point of failure to find out what the subwoofer's limits are. I can definitively tell you, that is not an easy task to perform with this sub using our 4000W+ capable amplifier. I have yet to burn up a voice coil on this driver even when the subwoofer has been continuously pushed over and over again in extreme testing that an end user of the subwoofer would never likely be able to replicate even if they were purposely trying to burn it up. Also, there are no power handling problems at all using neodymium magnets in this open motor structure . Yes, large ceramic magnets used in a motor structure are capable of dissipating more heat, however, because of the enclosed nature of ceramic motor structures (how they cover the voice coil bellow the top plate all the way to the back plate) , they need to be able to dissipate more heat due to being subjected to more heat from the voice coil. The open motor structure our driver uses does not require substantial heat dissipation by the magnets and is ultimately capable of higher sustained voice coil temperatures (thermal power handling).
Why use a sealed design over a vented design for the subwoofer? Read Matt's explanation posted above. He explains it very well. Sealed subs are inherently more effective at producing extreme low frequency (infrasonic) output in reasonably sized enclosures. For those that are interested in a vented version of the 21" sub, we can produce a vented version of this subwoofer which requires a 19 cubic ft enclosure (Fb=16Hz), but is capable of producing 125dB@20Hz and 113dB@16Hz, passing CEA2010 distortion levels. At 12Hz and below the sealed 21-FS/R has more output in a much more reasonably sized 6 cubic ft enclosure.

Regarding how the 21-FS/R performs/sounds, I look forward (like all of you) to reading Gene's opinions in his review. All I can say from my perspective as the engineer behind the product, is this; I have heard a number of very good subwoofer systems from various manufacturers over the 30 years I have worked in the industry, but as of yet, I have never heard/experienced another subwoofer like this.

Shane Rich
Technical Director
RBH Sound

Hey Shane. Wassup

So I hear you got a new subwoofer on the market.

Yeah

That's kinda cool

 

[Danzilla31]

So I just looked up some quick crude measurements for a box size for 19 feet cubed

This sub box's dimensions are 21 inches tall, 52 inches wide, and 49.625 inches deep.

That's fuggin awesome man

 

[TLS Guy]

Not only the frequencies from that organ, but frequencies from all pipe organs that have a true 32 foot pipe with a fundamental frequency of 16 Hz, are actually better suited for enjoying infrasonic sounds.

By the way, the fundamental frequency of the 64' pipe is 8 Hz. Not only the organ in Atlantic city has a 64' pipe. There's one at the Sydney Town Hall in Sydney, South Wales, Australia:

Sydney Town Hall Grand Organ - Wikipedia

en.wikipedia.org

As far as I know there are only two organs with pipes 64' in length: - Midmer-Losh organ at the Atlantic City Convention Center. The second one is the Pogson organ in the Organ Sydney Town Hall. Quite a few organs have 64' stops by the 8 Hz is derived from a beat frequency, like the Tibetan monks use to get their low tones.

 

[VonMagnum]

The RBH sub wins, but not by as much as you would think. The figures also illustrate the massive efficiency penalty you pay for a sealed design.

So of you had four RSL speedwoofers, you would get a gain of 6db over a single

Now we need to look not only at the output in the 16 Hz range and below, but well above it. This reveals the efficiency penalty of a sealed design and it is massive.

4 X RSL------------------------------------------ RBH
31.5 HZ 114.4db ------------------------120.1db

20Hz 110.6db -------------------------112.3db

16Hz 106.1db --------------------------105.5db

12.5Hz 93.7db --------------------------- 97.7db

However the four RSL subs would require 2000 watts for max output.

So going from 31.5 Hz to 16 Hz there are roughly five 3db steps in which the RBH sub has to double its power output. The RSL subs will be constant power and roll off 24db between 20 and 10 Hz, but amp output will not have to increase. So the RSLs are actually the more efficient solution by far, with only a penalty in the infrasonic range.
In my view that does not justify such a massive and costly engineering response the quality of the engineering not withstanding. The whole approach to me is intellectually unsatisfying.

Those numbers don't look all that silly to me, although I was actually assuming 9dB gain with 4 RSL subwoofers (not 6dB or 12dB as you get 3dB more output per additional sub and so 3 extra subs would be 9dB over just one within 1/4 wavelength).

Thus, my original statement that the 4 RSL setup wins at 20Hz (113.6 Vs 112.3) and 16Hz (109.1 Vs 105.5) and is very close at 12.5Hz (96.7 Vs 97.7) and not even terribly far off at even 31.5Hz (117.4 Vs 120.1) plus you have at least some flexibility to address room modes.

I just don't find it silly at all, not even with the 6dB numbers (where putting one farther apart would get you even more flexibility to address room modes).

But I'm not an expert like Gene so I'm probably wrong. Either way, I'm not dropping $10k on a sub. It'd be hard enough to fit 2 or 3 RSL subs in my room without tripping over them or blocking cabinet doors, etc. In fact, I'm thinking with ART in mind, 3 to 6 RSL 10 subs with some Crowson actuators for Infrasonic "feel" below 20Hz (they work at 5Hz even) might be the more room fitting (and hearing safe) option for me.

 

[TLS Guy]

Those numbers don't look all that silly to me, although I was actually assuming 9dB gain with 4 RSL subwoofers (not 6dB or 12dB as you get 3dB more output per additional sub and so 3 extra subs would be 9dB over just one within 1/4 wavelength).

Thus, my original statement that the 4 RSL setup wins at 20Hz (113.6 Vs 112.3) and 16Hz (109.1 Vs 105.5) and is very close at 12.5Hz (96.7 Vs 97.7) and not even terribly far off at even 31.5Hz (117.4 Vs 120.1) plus you have at least some flexibility to address room modes.

I just don't find it silly at all, not even with the 6dB numbers (where putting one farther apart would get you even more flexibility to address room modes).

But I'm not an expert like Gene so I'm probably wrong. Either way, I'm not dropping $10k on a sub. It'd be hard enough to fit 2 or 3 RSL subs in my room without tripping over them or blocking cabinet doors, etc. In fact, I'm thinking with ART in mind, 3 to 6 RSL 10 subs with some Crowson actuators for Infrasonic "feel" below 20Hz (they work at 5Hz even) might be the more room fitting (and hearing safe) option for me.

I calculated it on the subs being separated. Then you gain 3db. every time you double the power. So four subs gives you 6db over one.

 

[highfigh]

Not only the frequencies from that organ, but frequencies from all pipe organs that have a true 32 foot pipe with a fundamental frequency of 16 Hz, are actually better suited for enjoying infrasonic sounds.

By the way, the fundamental frequency of the 64' pipe is 8 Hz. Not only the organ in Atlantic city has a 64' pipe. There's one at the Sydney Town Hall in Sydney, South Wales, Australia:

Sydney Town Hall Grand Organ - Wikipedia

en.wikipedia.org

There's no way my speakers were outputting 8Hz or 16Hz and with REW, they fall off higher than 32Hz, but that doesn't mean they weren't trying. The modulation was very easy to hear, basically because the two octaves involved are below the port tuning frequency although the notes in the useful range of the speakers came through very nicely, considering the small woofer size of 6-1.2" in a 2.5 way.

 

[highfigh]

I calculated it on the subs being separated. Then you gain 3db. every time you double the power. So four subs gives you 6db over one.

But, is that with additional amplifier channels? One speaker at a specified power output produces what it will, but the output from an additional speaker depends on how it's powered- is it parallel, or series with the first? If parallel, can the amplifier drive both at full power output at all frequencies with 1/2 of the impedance? If in series, the output from two drivers will be the same as one, due to doubling the impedance. Adding a speaker AND driving it with its own amplifier channel adds 6dB, due to doubling the total output power and cone area/pistonic volume.

 

[highfigh]

So I just looked up some quick crude measurements for a box size for 19 feet cubed

This sub box's dimensions are 21 inches tall, 52 inches wide, and 49.625 inches deep.

That's fuggin awesome man

Why not be practical and use commonly available sheet goods (plywood, MDF, etc)?

FWIW, ElectroVoice had designs for the 30W woofer with slightly different F3- the larger enclosure enabled 17.5Hz and it was 28.5" x 4' x 8'.

I wish I could have kept mine.

 

[Verdinut]

There's no way my speakers were outputting 8Hz or 16Hz and with REW, they fall off higher than 32Hz, but that doesn't mean they weren't trying. The modulation was very easy to hear, basically because the two octaves involved are below the port tuning frequency although the notes in the useful range of the speakers came through very nicely, considering the small woofer size of 6-1.2" in a 2.5 way.

Forget about the 8 Hz fundamental as there is no CD containing it. I don't think that you would find a CD or any other audio medium with such low frequency. There are not many CDs with 32' stop recordings. I have one CD which has some 32' stop passages, especially on track No. 17 (Shostakovich's Credo) :

Amazon.com

Be careful with driving your speakers below their cabinet tuning frequency. Below that point, the drivers are no longer controlled by any air pressure within their box, and it's rather easy to get their cones move beyond their xmax.

You would need good subs such as the Dayton RSS390HF-4s that I'm using in my three front cabinets. Their cabinets are tuned to 16 Hz and I can get an F3 at 20 Hz without any EQ.