RBH Sound SX-1212P/R Subwoofer Review

[Steve81]

But since smaller drivers have less excursion than a single 14" driver, would the 3 x 8" drivers be closer to the 2 x 10" drivers, assuming similar power and cabinet volume?

Let's take some real world examples of driver displacement:

The aforementioned TC LMS-R 12" driver has an Sd of 491cm^2 and an xmax of 25.4mm for one way displacement of ~1.25L.
A Dayton Ultimax 10" driver has an Sd of 328cm^2 and an xmax of 19mm for a one way displacement of 0.62L.
Three 8" ScanSpeak Revelators have a combined Sd of 660cm^2 and an xmax of 9mm for a combined one way displacement of 0.59L.

*disclaimer: rated linear displacement obviously isn't the only measure of a driver's worth.

 

[AcuDefTechGuy]

Let's take some real world examples of driver displacement:

The aforementioned TC LMS-R 12" driver has an Sd of 491cm^2 and an xmax of 25.4mm for one way displacement of ~1.25L.
A Dayton Ultimax 10" driver has an Sd of 328cm^2 and an xmax of 19mm for a one way displacement of 0.62L.
Three 8" ScanSpeak Revelators have a combined Sd of 660cm^2 and an xmax of 9mm for a combined one way displacement of 0.59L.

*disclaimer: rated linear displacement obviously isn't the only measure of a driver's worth.

So Revel seems quite optimistic equating 3 x 8" drivers to 1 x 14" driver, especially if the overall cabinet volume is similar - unless Revel was talking about a 14" driver in a much smaller volume.

 

[shadyJ]

Like Gene touched on, there is still more to output performance than displacement which must be considered. Fs, response shape, motor force vs air resistance, power compression, etc. Smaller drivers tend to have a higher fs, below which linear displacement is reduced. Also, something like an Ultimax 10" would need a bigger cabinet than the LMS-R 12" to perform well, despite a lesser sd. The TC Sounds power handling will also be very different from the Ultimax.

 

[Steve81]

So Revel seems quite optimistic equating 3 x 8" drivers to 1 x 14" driver

They're simply talking about the radiating surface, nothing more, nothing less. But yes, it wouldn't be wise for a trio of 8" mid/woofers to get into a displacement competition with a 14" long throw subwoofer driver.

 

[Irvrobinson]

They're simply talking about the radiating surface, nothing more, nothing less.

And indirectly assuming similar xmax. Actually, according to my in-room measurements, the pair of Salon2s produces surprisingly strong low-distortion 20Hz and 25Hz test tones. I have no doubt that one could build a very power sub from an array of three to six appropriate 8" drivers.

 

[gene]

I guess bigger numbers sell better.

Hey, Steve, assuming similar excursion, power, etc., do these numbers equate (3 x 8" = 1 x 14") ?

Part of that is true. Having all of the drivers on the front baffle looks more impressive. Side firing woofers can be tricky to place in a room. So there you go.

 

[Ricci]

Thanks for the compliments on the review guys. To be honest I was surprised at how powerful the SX-1212R was as well. At the end of the day in order to produce tons of deep bass requires a lot of air to be moved. The port obviously helps immensely but the drivers still require a lot of clean stroke or there would be a reduction or notch in maximum output above the port tune. The drivers in that sub really don't look like anything special compared to some of the heavyweights like the JL's or SVS Ultra but it is obvious that someone engineered them well and made the most of the components used. They had much greater linear displacement than I thought they would have. The Speakerpower amps are just beastly as well. There is a big difference in between those and a "1000w" BASH or Ice plate.

Multiple smaller drivers have some advantages and some disadvantages. Multiple smaller coils to share the power often do better than one much bigger one. The smaller cones offer more options for cabinet geometry and driver placement. However smaller driver frames ultimately limit the size of the suspension components and the voice coil diameter, not to mention the size of the motor. All of these limit the amount of power handling and linear stroke that can be engineered into the driver easily or cost effectively. This is why you do not see 6.5" and 8" drivers claiming 25mm Xmax. Also multiple smaller drivers with the same displacement potential as a single larger driver may ultimately cost more and weigh more than the single larger driver.

 

[gene]

A Note about Amplifier Price

Guys seeing the BIG difference in price between powered and non-powered versions of this sub, I asked RBH for the scoop on this.

Here is what they said:

<!--[if gte mso 9]><![endif]--> The simple answer to the question is markup. We have nothing to hide. We spend $1500 on the amp and we have to make a profit on it when we sell it to a dealer. The dealer has to make profit on it when it is sold to the consumer. As Josh stated in his review, this amp is the real deal. Not all amps with similar power ratings are equal. I have not seen a better amp with this type of power output. This is an amp we should never have to replace no matter how hard the sub is driven. It is made in the USA which also appeals to our foreign customers. The amp for the SX-1212PR is programed with our custom EQ, limiter settings etc. You will not get that when buying an amp from any other source, nor will you get our warranty which covers the complete amp - sub package.


Yes, we are aware there are less expensive amps with similar power ratings available. That is the reason we sell the passive version of the sub. If the consumer wants to mate the sub with a less expensive amp or even a similar amplifier purchased from Speaker Power, go for it! Buy the passive sub and do it!!!

<!--[if gte mso 9]><![endif]--><!--[if gte mso 10]> <![endif]-->

 

[GranteedEV]

Nothing wrong with markup. It's business.

 

[AcuDefTechGuy]

The important thing is actually having the option of either active or passive subwoofer with RBH.

You don't even have that option with most subwoofers, with the exception of a few companies like Funk Audio.

 

[crossedover]

The important thing is actually having the option of either active or passive subwoofer with RBH.

You don't even have that option with most subwoofers, with the exception of a few companies like Funk Audio.

I don't see many how that's the most important. Can you imagine JL or velodyne putting out their small sealed subs without an amp, that would be a nightmare.

 

[AcuDefTechGuy]

Can you imagine JL or velodyne putting out their small sealed subs without an amp, that would be a nightmare.

Why would that be a nightmare?

The first sub I owned back in 1992 was a little NHT 10" passive subwoofer that came with an external 80W sub amp. The only difference was that the amp was external.

This same little 10" sub & 80W amp is now installed in the family room of my brother's 4,000SF house 22 years later.

I don't see the nightmare.

 

[crossedover]

The amps are specifically engineered to the driver. All filtering, and EQ and in some cases servo control. Getting a velodyne dd10 with out the amp and using a crown pro amp to drive it wouldn't work. Not all subs are meant to be driven with off the shelf amps.

 

[Irvrobinson]

Getting a velodyne dd10 with out the amp and using a crown pro amp to drive it wouldn't work AS WELL.

There, fixed that for you.

 

[AcuDefTechGuy]

The amps are specifically engineered to the driver. All filtering, and EQ and in some cases servo control. Getting a velodyne dd10 with out the amp and using a crown pro amp to drive it wouldn't work. Not all subs are meant to be driven with off the shelf amps.

It is important to use an amp that is rated to the specification of the subwoofer.

The NHT SW2P passive sub was rated for 80W, so NHT supplied an 80W amp.

The RBH SX-1010/R passive sub is rated for 500W, so I would only use an amp that can only output about 500W into 4 ohms.

The Velodyne SC-600 IF/IC passive sub is rated for 200W, so I would only use an amp that can only output about 200W into 4 ohms.

It's almost the same way with loudspeakers. I don't recommend using a 1KW amp on speakers that are rated for 100W max.

I've used both passive subs and active subs. And I will never buy another active sub. Passive subs have worked extremely well for me. I let Audyssey EQ the bass + Dynamic EQ and let my amps power the passive subs. The resulting bass is mellifluous.

Options are good. You want active, you buy active. You want passive, you buy passive.

 

[mtrycrafts]

.... I don't recommend using a 1KW amp on speakers that are rated for 100W max.

....

But, but, but, how will you sell more drivers unless you kill them with power beyond their rating?

 

[AcuDefTechGuy]

But, but, but, how will you sell more drivers unless you kill them with power beyond their rating?

I'm not a manufacturer, so I don't know. But I wonder if there were ever a lot of complaints about blown passive subwoofers?

I've seen passive subs that are 30 years old and still sound great. My brother's NHT passive sub is 22 years and still sounds great and shakes the big room like a rag doll.

I've heard a lot more of blown active subs (drivers and internal amps).

 

[Irvrobinson]

Why would that be a nightmare?

The first sub I owned back in 1992 was a little NHT 10" passive subwoofer that came with an external 80W sub amp. The only difference was that the amp was external.

This same little 10" sub & 80W amp is now installed in the family room of my brother's 4,000SF house 22 years later.

I don't see the nightmare.

I don't think it's a nightmare, but passive subs with external amps do seem analogous to buying a modern automobile engine and using a generic engine management system, and not the one from the engine manufacturer. The combination might work, but it won't run as well as the dedicated design. I don't even want to know what Velodyne did to get my DD18+ to perform the way it does. I'm guessing I would be appalled if I knew.

Yeah, I get it that you use Audessey to pre-distort the signal for its room correction strategy, but my impression, perhaps incorrect, is that's a blunter instrument than what a sub manufacturer does with a custom amp.

 

[Steve81]

Yeah, I get it that you use Audessey to pre-distort the signal for its room correction strategy, but my impression, perhaps incorrect, is that's a blunter instrument than what a sub manufacturer does with a custom amp.

I'd opine that the more critical piece is the limiters / protection that a custom amp provides, particularly with a vented subwoofer. It takes less power than you'd expect to bottom a woofer being fed a lot of content below port tune.

 

[AcuDefTechGuy]

I don't think it's a nightmare, but passive subs with external amps do seem analogous to buying a modern automobile engine and using a generic engine management system, and not the one from the engine manufacturer. The combination might work, but it won't run as well as the dedicated design. I don't even want to know what Velodyne did to get my DD18+ to perform the way it does. I'm guessing I would be appalled if I knew.

Yeah, I get it that you use Audessey to pre-distort the signal for its room correction strategy, but my impression, perhaps incorrect, is that's a blunter instrument than what a sub manufacturer does with a custom amp.

There is no difference between an internal amp vs external amp. You could put the same DSP/XO/Limiter in an external amp. The Funk 18.2 sub uses an external DSP/XO/amp.

I'm sure proponents of active speakers will say that there is no way passive speakers + external amps could perform like active speakers with their special engineered match of drivers + DSP/XO/amp. And loudspeakers are a lot more complex than subwoofers. So if you're comparing sub amps to car engines, let's compare loudspeakers to a B1 Stealth Bomber engine.

I wonder why proponents of subs with internal amps don't all buy active speakers with internal amps. The internal amps will make the subs and speakers better, right?

Another case in point - my Linkwitz Orion are 100% active. Yet, the DSP/Crossover/Amps are all EXTERNAL.