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

[ryanosaur]

it wasn't easy. I had to employ two All Pass Filters to not get it to cancel with the other ported subs in my system. I may investigate sealing ALL of the ported subs in my system to eliminate the APFs. I have so much headroom in bass that it may be worth the output sacrifice. It will certainly reinforce the infrasonics which my family won't appreciate

I can’t imagine that your friends at RBH wouldn’t replace all your Subs with the new 21s for a smallSVS style upgrade fee!

 

[VonMagnum]

Wouldn't it be a better idea to buy 4 RSL 12S Speedwoofer subs for about 1/3 the price, which could then not only outperform this sub down to 16Hz (and be within 2dB at 12.5Hz), but with 4 subs you could apply DIRAC ART (available already on Storm and coming soon for the Monoprice HTP-1) or at least smooth your room response (unless someone wants to spend $30k+ with at least three of these for ART and at least two to smooth room response with a Mini-DSP or DLBC).

With the Marantz Cinema10, you could have stereo bass front-to-back, left/right or quadrant based. They'd also be considerably easier to place.

I know I'm planning on upgrading to the Speedwoofer 12s (at least two, if not three).

 

[TLS Guy]

I doubt the RBH 21-SF/R will produce anywhere near the magnitude of sonic boom caused by the F-4 jet.

It is not about spl. It is about how fast it can raise the pressure inside the box. So the smaller the box and the faster the driver can move, will be the determinant. This is not about playing a recording of a sonic boom.

 

[ryanosaur]

Wouldn't it be a better idea to buy 4 RSL 12S Speedwoofer subs for about 1/3 the price, which could then not only outperform this sub down to 16Hz (and be within 2dB at 12.5Hz), but with 4 subs you could apply DIRAC ART (available already on Storm and coming soon for the Monoprice HTP-1) or at least smooth your room response (unless someone wants to spend $30k+ with at least three of these for ART and at least two to smooth room response with a Mini-DSP or DLBC).

With the Marantz Cinema10, you could have stereo bass front-to-back, left/right or quadrant based. They'd also be considerably easier to place.

I know I'm planning on upgrading to the Speedwoofer 12s (at least two, if not three).

Truly depends on goals and budget.
The 12s compresses pretty readily at full tilt, though. It is not the end-all solution that many want it to be. Mind, it does impress… but until we see a full set of measurements for this RBH, judging and critiquing it by the capabilities of budget subs is relatively meaningless.

If you are looking for highest quality reproduction, there are better products than the Speedwoofers to be certain. Budget and goals tell all, however. Finding the individual balance for each individual’s values is up to them.

 

[gene]

Wouldn't it be a better idea to buy 4 RSL 12S Speedwoofer subs for about 1/3 the price, which could then not only outperform this sub down to 16Hz (and be within 2dB at 12.5Hz), but with 4 subs you could apply DIRAC ART (available already on Storm and coming soon for the Monoprice HTP-1) or at least smooth your room response (unless someone wants to spend $30k+ with at least three of these for ART and at least two to smooth room response with a Mini-DSP or DLBC).

With the Marantz Cinema10, you could have stereo bass front-to-back, left/right or quadrant based. They'd also be considerably easier to place.

I know I'm planning on upgrading to the Speedwoofer 12s (at least two, if not three).

LOL that's silly. 4 RSL's cannot match the output of this single 21" RBH. The RBH is sealed and will see a +9dB output advantage at infrasonic frequencies due to room gain over a similar ported sub. I already have 4 subs. The 21" is added for infrasonics.

 

[ryanosaur]

The 21" is added for infrasonics.

And helping that new foundation settle. Don't forget that.

 

[shadyJ]

Yes, we concentrate on spl, but the damage from excess low frequency vibrations are an evolving research topic as you found out. I think there is quite enough data already to be very concerned about it. I would say that RBH sub should NOT go into production. I would advise any professional installer not to install that sub for liability and health issues.

I have been concerned about this in my own system. As you know I don't use sub drivers, but I do have those large lines that really make an acoustic coupling to the room. They also measure much lower than predicted. I suspect the room plays a part on this, but not all of it.

Now the only musical instrument that produces frequencies below 20 Hz is the pipe organ. The lowest note has an F of 16 Hz. I know there is the odd organ that has stops labelled at 64 ft. but these are rare, and contrived from the physics of beat frequencies.

As you know I am an organ enthusiast, and these instruments do rattle my rib cage, and shake the floor. I don't watch a lot of movies, but I get concerned when the grandchildren rattle the furniture downstairs watching some action movies, and I intervene.

I have however had increasing concerns about LF damage to the human body, and funnily enough I did reduce the sub signal to the four drivers on the long TLs a few weeks ago.

My impression is that most systems I hear have subs too loud. I suspect a lot of members here are over woofered, and probably dangerously so.

Balance in all things is an axiom to live by, and that includes low frequencies.

I don't believe any of this sonic boom in subwoofers business at all. I have run many subs at full throttle for long durations, both outdoors and indoors, and have never experienced anything like this. I have never heard of anyone causing anything like this, and there are people with more powerful subwoofers than the RBH 21" who run them at high levels routinely. I haven't seen any literature describing this in any AES, ASA, or IEEE papers that describe anything like this. I think your concerns on this matter are not warranted.

As for harm from high amplitude low frequencies. the literature I have seen suggests it is not totally harmless, but much less harmful than exposure to loudness at higher frequencies where our ears are more sensitive.

 

[shadyJ]

All you have to do is look at the overall design and engineering of Funk and Harbottle subs and it's clear they are superior in both. But you keep pushing one of your site's sponsors. We all have to eat.

I am looking at the overall design and engineering of those subs, and I don't know why you think Funk/Harbottle subs are better designed. There is nothing to suggest that. These are unwarranted presumptions with no data to support your conclusions. The RBH 21" looks like a perfectly viable alternative, and what's better is it probably would not take many months after ordering to expect delivery.

 

[shadyJ]

One example is the Harbottle Audio/Funk Audio Drivers where their design has effectively eliminated compression at the highest output levels. The DataBass measurements done many years back on the earlier models are effectively "textbook" of what long term output should look like.

I don't have enough time to fully unpack this subject, but I will say that compression can come from a variety of sources, and some are more benign than others. In most mass-produced commodity subs, the compression that you see in test measurements occurs when the amplitude drive level exceeds the equalized response. So it isn't the driver that is compressing, it is some filter in the signal processing.

Actual thermal compression in the driver is an entirely different beast, and it isn't shown very well in ours -or anyone's- test suites. If you want to see what that is like, set up REW with one of your subs along with a microphone. Set your subs to full volume, and max out the signal chain without risking signal clipping. Set the tone generator to CEA-2010 bursts, and have the 'repeat busts' box checked. Open up REW's RTS, start up the CEA-2010 bursts on the tone generator, and watch how the recorded levels drop after the testing has started. This is an audible as well as measurable occurrence.

The funny thing is both the RBH and Funk/Harbottle subs have used an unfortunate design choice if they really wanted to thwart compression since they have used neodymium magnets in the motor. Neo doesn't have nearly the surface area to radiate heat that ferrite motors have, so ferrite performs better in this respect. RBH and Funk/Harbottle were probably forced to use neo because of the weight and internal stability issues.

 

[VonMagnum]

LOL that's silly. 4 RSL's cannot match the output of this single 21" RBH. The RBH is sealed and will see a +9dB output advantage at infrasonic frequencies due to room gain over a similar ported sub. I already have 4 subs. The 21" is added for infrasonics.

I'm sorry I'm being "silly" as I'm not a subwoofer expert. But doesn't room gain also apply to ported subs, particularly down to their port frequency? The RSL is tuned to 16Hz I gather? (Infrasonic the last time I checked) and from what "silly" things I understand is that the really big advantage with a sealed box for room gain would be below that frequency due to the faster roll off on ported sub (not because room gain doesn't actually affect ported subs as well). I'm just going by the reviews burst measurements quasi-anechoic so maybe I missed how the RBH can put out more bass at 20Hz or even 16Hz than four RSL 12s units. At 10Hz, there's no question about it.

Like I said, I'm not an expert on subs, which is why I asked a question based on the quasi-anechoic measurements based on my needs (not yours as you seem to be assuming by your comments about Infrasonic use only and already having four subs).

Now you might want 10Hz tactile feel from a real sub, but 14-16Hz is about as low as I imagine ever needing to go (pipe organ). Explosions aren't that interesting to me and a Crowson actuator would give safer Infrasonic tactile sensations (for both my hearing and my house structure) than blasting oneself below 16Hz for $650 per chair (plus amp) and a DIY HoverEze would be an more reasonably priced. But maybe my silly non-expert self is still missing something here?

 

[isolar8001]

I doubt the RBH 21-SF/R will produce anywhere near the magnitude of sonic boom caused by the F-4 jet.

Oh Man, the F4 is my all time favorite jet !!
I worked at a stereo shop in the 90's....one of our in house repairman was stationed on an aircraft carrier during Vietnam.
One day I asked him if he got to see a lot of F4's.
He jumped up out of his chair (he was quite the character) and started shouting.....

"Those MFing Phantoms !!! The whole Gdamned ship would shake when one of those fat bastards hit the deck, and they hit the MFing deck all day and all night !! F those F4's !!!!!"
I will never forget that response.

 

[TLS Guy]

I don't believe any of this sonic boom in subwoofers business at all. I have run many subs at full throttle for long durations, both outdoors and indoors, and have never experienced anything like this. I have never heard of anyone causing anything like this, and there are people with more powerful subwoofers than the RBH 21" who run them at high levels routinely. I haven't seen any literature describing this in any AES, ASA, or IEEE papers that describe anything like this. I think your concerns on this matter are not warranted.

As for harm from high amplitude low frequencies. the literature I have seen suggests it is not totally harmless, but much less harmful than exposure to loudness at higher frequencies where our ears are more sensitive.

What Bob did was to use a small powerful driver in a very small sealed box. So the pressure fluctuations were enormous. None of any of the subs you have tested would create a situation like that. This has to be a sealed box with huge pressure and temperature changes moment to moment. I just have a feeling that sooner or later with these powerful drivers in smaller and smaller sealed boxes, and piling on the power, someone is going to get a very nasty surprise, they never expected.

 

[ryanosaur]

I don't have enough time to fully unpack this subject, but I will say that compression can come from a variety of sources, and some are more benign than others. In most mass-produced commodity subs, the compression that you see in test measurements occurs when the amplitude drive level exceeds the equalized response. So it isn't the driver that is compressing, it is some filter in the signal processing.

Actual thermal compression in the driver is an entirely different beast, and it isn't shown very well in ours -or anyone's- test suites. If you want to see what that is like, set up REW with one of your subs along with a microphone. Set your subs to full volume, and max out the signal chain without risking signal clipping. Set the tone generator to CEA-2010 bursts, and have the 'repeat busts' box checked. Open up REW's RTS, start up the CEA-2010 bursts on the tone generator, and watch how the recorded levels drop after the testing has started. This is an audible as well as measurable occurrence.

The funny thing is both the RBH and Funk/Harbottle subs have used an unfortunate design choice if they really wanted to thwart compression since they have used neodymium magnets in the motor. Neo doesn't have nearly the surface area to radiate heat that ferrite motors have, so ferrite performs better in this respect. RBH and Funk/Harbottle were probably forced to use neo because of the weight and internal stability issues.

I know that there is a lot that can be unpacked, and I am not trying to claim one design as superior to another... rather using one I am a touch more familiar with as an example for one method of designing for the Extreme Subwoofer market...

That said, it is worth adding that Cody's design utilizes an Aluminum Dustcap to help with heat in the VC as well as the back of the motor housing being vented.

As has been detailed in many threads, there is a balance in all aspects of the design phase.

 

[TLS Guy]

I know that there is a lot that can be unpacked, and I am not trying to claim one design as superior to another... rather using one I am a touch more familiar with as an example for one method of designing for the Extreme Subwoofer market...

That said, it is worth adding that Cody's design utilizes an Aluminum Dustcap to help with heat in the VC as well as the back of the motor housing being vented.

As has been detailed in many threads, there is a balance in all aspects of the design phase.

I just favor elegant design. There is nothing elegant about producing a huge driver with a massive motor system throwing it in a sealed box and providing insane quantities of power. That is the very definition of crude brute force, and does nothing to arouse my interest. I do think this may partly be cultural, as brute force solutions are in many ways archetypically American.

 

[ryanosaur]

I just favor elegant design. There is nothing elegant about producing a huge driver with a massive motor system throwing it in a sealed box and providing insane quantities of power. That is the very definition of crude brute force, and does nothing to arouse my interest. I do think this may partly be cultural, as brute force solutions are in many ways archetypically American.

Can't argue with this!

What has been interesting to watch is that a majority of these Raw Drivers that are definitely showing as better in a Sealed Alignment do seem to also behave well in a large ported cabinet. This is getting beyond my ability to understand well, but many do it and have shown it to be efficacious. The Stereo Integrity 24" is one that can benefit from a large ported cabinet... About the size of a Fridge! *shrugs

Similarly, it seems we should see more on the Sealed variant of this RBH as well as a very large Ported build, too!

 

[Verdinut]

LOL that's silly. 4 RSL's cannot match the output of this single 21" RBH. The RBH is sealed and will see a +9dB output advantage at infrasonic frequencies due to room gain over a similar ported sub. I already have 4 subs. The 21" is added for infrasonics.

Which filter frequency are you using for the crossover if any between the RSLs and this RBH?

 

[ryanosaur]

Which filter frequency are you using for the crossover if any between the RSLs and this RBH?

He’s not using the RSL Speedwoofers.

 

[TLS Guy]

I don't believe any of this sonic boom in subwoofers business at all. I have run many subs at full throttle for long durations, both outdoors and indoors, and have never experienced anything like this. I have never heard of anyone causing anything like this, and there are people with more powerful subwoofers than the RBH 21" who run them at high levels routinely. I haven't seen any literature describing this in any AES, ASA, or IEEE papers that describe anything like this. I think your concerns on this matter are not warranted.

As for harm from high amplitude low frequencies. the literature I have seen suggests it is not totally harmless, but much less harmful than exposure to loudness at higher frequencies where our ears are more sensitive.

It is not just hearing that low frequencies damage, but the CNS as a whole and even cardiovascular damage. The effects of low frequency abuse are significantly different from spl. abuse per se. They do not just involve hearing. There has not been a lot of investigation until recently and LF noise from wind farms has prompted a resurgence of interest.

Here is a good review article of the literature. Although it goes back to 1920, this is a relatively new area of study.

I know for certain that I don't like excessive bass, but a well balanced sound. I have stated here often that I think subwoofers are frequently abused to the detriment of realistic accurate reproduction. I do not believe these 'mega' subs are required for accurate balanced reproduction in the home. As you know I do not use a sub as such in my HT room. However I believe the reproduction to be balanced and accurate to concert hall levels, with no frequency band favored over another.

I think this topic will receive increasing attention in the years ahead. As I have said, at this time I advise caution, and reinforce the dictum of Primum non Nocere!

 

[gene]

All you have to do is look at the overall design and engineering of Funk and Harbottle subs and it's clear they are superior in both. But you keep pushing one of your site's sponsors. We all have to eat.

We've reviewed Funk subs in the past. They were good but not really class leading from what I recall from this review. Cabinetry was good however.

Funky Waves FW 12.X Subwoofer Review

The Funkywaves FW 12.X Ported 12” subwoofer is a beautifully crafted piece of furniture. It offers true 20Hz performance with a unique sound not matched by any other sub in our comparison.

www.audioholics.com

very inefficient driver needs lots of power to play loud at least from our 2011 review. I'd imagine they've made improvements since.

I promote what happens to be really good and class leading such as products from Perlisten, RBH Sound, Paradigm, etc. It just happens when our reviews are chock full of positive objective and subjective comments, said companies want to advertise with us. You seem to take issue with this site's success. You're welcome to not participate on this forum if capitalism offends you.

 

[gene]

I'm sorry I'm being "silly" as I'm not a subwoofer expert. But doesn't room gain also apply to ported subs, particularly down to their port frequency? The RSL is tuned to 16Hz I gather? (Infrasonic the last time I checked) and from what "silly" things I understand is that the really big advantage with a sealed box for room gain would be below that frequency due to the faster roll off on ported sub (not because room gain doesn't actually affect ported subs as well). I'm just going by the reviews burst measurements quasi-anechoic so maybe I missed how the RBH can put out more bass at 20Hz or even 16Hz than four RSL 12s units. At 10Hz, there's no question about it.

Like I said, I'm not an expert on subs, which is why I asked a question based on the quasi-anechoic measurements based on my needs (not yours as you seem to be assuming by your comments about Infrasonic use only and already having four subs).

Now you might want 10Hz tactile feel from a real sub, but 14-16Hz is about as low as I imagine ever needing to go (pipe organ). Explosions aren't that interesting to me and a Crowson actuator would give safer Infrasonic tactile sensations (for both my hearing and my house structure) than blasting oneself below 16Hz for $650 per chair (plus amp) and a DIY HoverEze would be an more reasonably priced. But maybe my silly non-expert self is still missing something here?

CEA 2010 data is done anechoic and doesn't reflect how a sub couples in a real room. That's a real limitation of just going off these numbers and a discussion I've been having with Matt Poes, James Larson and even Dan Roemer from Perlisten. A sealed sub that has a large high excursion driver like the RBH 21" and a high power amp can both be boosted at low F and take advantage of the shallow rolloff characteristics inherent in a sealed design without a deliberate HFP added to protect the driver. I have 4 ported RBH 1212 subs in my room (which are more capable subs than the RSL 12s Speedwoofer) that roll off at 15Hz (-3dB) even if I boost. This 21" is flat to 10Hz and I can even extend to 5Hz if I add more boost. If you want true infrasonic, high output sealed has advantages.