RBH Sound 61-SFM/R Tower Speaker Review

[shadyJ]

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It’s strange to think that modular designs aren’t more popular with tower speakers. They are easier to deal with, logistically; instead of a single large unit that requires heavy-duty packing, the speaker is packed in two boxes which makes it less prone to shipping damage. Modular designs have inherent construction advantages that single-piece towers don’t necessarily have; bracing and woofer compartment separation is built-in with modular systems. They can also simplify design where the internal space required by the drivers are more easily designed for and accommodated. These aspects make it easier for them to be a better loudspeaker.

RBH Sound has had dalliances with modular tower systems with good results, but usually, that type of setup was reserved for their expensive flagship systems such as the SVTRS Active Towers. However, for the 61-SFM.R Tower, the subject of today’s review, they attempt to bring modular design down to a much more affordable price point. How well have they succeeded? Read our full review to find out…

READ: RBH Sound 61-SFM/R Dloor-Standing Loudspeaker Review

 

[Bobby Bass]

View attachment 68864​

It’s strange to think that modular designs aren’t more popular with tower speakers. They are easier to deal with, logistically; instead of a single large unit that requires heavy-duty packing, the speaker is packed in two boxes which makes it less prone to shipping damage. Modular designs have inherent construction advantages that single-piece towers don’t necessarily have; bracing and woofer compartment separation is built-in with modular systems. They can also simplify design where the internal space required by the drivers are more easily designed for and accommodated. These aspects make it easier for them to be a better loudspeaker.

RBH Sound has had dalliances with modular tower systems with good results, but usually, that type of setup was reserved for their expensive flagship systems such as the SVTRS Active Towers. However, for the 61-SFM.R Tower, the subject of today’s review, they attempt to bring modular design down to a much more affordable price point. How well have they succeeded? Read our full review to find out…

READ: RBH Sound 61-SFM/R Dloor-Standing Loudspeaker Review

James thanks for another review. Beyond The equipment info your music listening always has me searching Qobuz and checking out the albums and songs you play to test the equipment. I now have a few more to checkout. Thanks

 

[AcuDefTechGuy]

I’ve always love modular towers, especially if they are towers of power. I can handle a 100-lb speaker, but not 200-lb speaker.

 

[AcuDefTechGuy]

Superb sound quality, Response of +/- 2.0dB, and in-room bass response of 30Hz.

 

[TLS Guy]

View attachment 68864​

It’s strange to think that modular designs aren’t more popular with tower speakers. They are easier to deal with, logistically; instead of a single large unit that requires heavy-duty packing, the speaker is packed in two boxes which makes it less prone to shipping damage. Modular designs have inherent construction advantages that single-piece towers don’t necessarily have; bracing and woofer compartment separation is built-in with modular systems. They can also simplify design where the internal space required by the drivers are more easily designed for and accommodated. These aspects make it easier for them to be a better loudspeaker.

RBH Sound has had dalliances with modular tower systems with good results, but usually, that type of setup was reserved for their expensive flagship systems such as the SVTRS Active Towers. However, for the 61-SFM.R Tower, the subject of today’s review, they attempt to bring modular design down to a much more affordable price point. How well have they succeeded? Read our full review to find out…

READ: RBH Sound 61-SFM/R Dloor-Standing Loudspeaker Review

Thanks for another insightful review.

However, I am noting a trend to very low frequency passive crossovers, and this is a terrible idea and trend. It needs to stop now.

Just look at that low pass inductor, it is wound with a huge length of wire with a gauge approaching hair.

One thing you should have done was to have measured the DC resistance of that coil while you had it the crossover out.

I bet it would have knocked your socks off!. I emphasise again, with loudspeakers the standard measurements are not the whole story. I can absolutely bet I would not like the sound of those speakers. What they did is BAD design period.

Not only that, but this trend is driving mids down too low right into the BSC range. So that speaker will be wanting when all the cellists and double basses are ff.

Then we get to the issue of sub integration. This approach just magnifies the problem. And as you say a sub crossover is generic for a start which is suboptimal. I have a strong hunch that a lot of so called "room corrections" are actually in major part dealing with this very issue.

This all really does make the strongest case for active speakers, as this is the only way you can really get this right.

I do consider that I got this right in my design, with enough power in the midrange and sharing the power of BSC, as well as making the latter available to control.

So having two powerful mids and usung drivers that can assist the mids with BSC is a actually a big advance.

This is not rocket science and actually simple in an active speaker, as you can get the power splits dead right and mix in the sub/LFE is a seamless manner. This is I know a valid and far better approach.

 

[AcuDefTechGuy]

I think the market for the 61-SFM/R are people who have smaller rooms and/or don’t want earthquake subwoofer bass, and want a “tower” without additional subwoofers.

They don’t want a typical looking “monitor + sub” for aesthetics. They want just 2 towers that have enough bass (30Hz) for them.

So if I were in this market, I would treat this tower as a bookshelf + sub - feed the L/R audio signal to the bookshelf cabinet and feed the LFE/Sub output to a sub-amp to the bass cabinet. Thus, it becomes a typical monitor + sub, but aesthetically looks like a single tower speaker.

 

[ryanosaur]

Indeed, @shadyJ , thank you again for another good review!

Interesting product. I need to look at it more when I have some time to dig deeper.

 

[Bobby Bass]

I’ve always love modular towers, especially if they are towers of power. I can handle a 100-lb speaker, but not 200-lb speaker.

I hear you My Arendals are 111 lbs. each and that’s all I can move

 

[gene]

Thanks for another insightful review.

However, I am noting a trend to very low frequency passive crossovers, and this is a terrible idea and trend. It needs to stop now.

Just look at that low pass inductor, it is wound with a huge length of wire with a gauge approaching hair.

One thing you should have done was to have measured the DC resistance of that coil while you had it the crossover out.

I bet it would have knocked your socks off!. I emphasise again, with loudspeakers the standard measurements are not the whole story. I can absolutely bet I would not like the sound of those speakers. What they did is BAD design period.

Not only that, but this trend is driving mids down too low right into the BSC range. So that speaker will be wanting when all the cellists and double basses are ff.

Then we get to the issue of sub integration. This approach just magnifies the problem. And as you say a sub crossover is generic for a start which is suboptimal. I have a strong hunch that a lot of so called "room corrections" are actually in major part dealing with this very issue.

This all really does make the strongest case for active speakers, as this is the only way you can really get this right.

I do consider that I got this right in my design, with enough power in the midrange and sharing the power of BSC, as well as making the latter available to control.

So having two powerful mids and usung drivers that can assist the mids with BSC is a actually a big advance.

This is not rocket science and actually simple in an active speaker, as you can get the power splits dead right and mix in the sub/LFE is a seamless manner. This is I know a valid and far better approach.

I don't think this is a fair assessment at all and I Think you missed the point of this product. It's designed as a 2CH solution for those that can't place subs at separate locations in their room. RBH did NOT Intend this to be a fullrange speaker that people would also add separate powered subs. The fact that you can bi-amp this system and adjust bass to taste with their own DSP amps with PEQ is where a solution like this really shines. If you want a multi-ch system with separate powered subs, don't buy the bass modules and use the very competently designed satellite speakers as LCRs as James mentioned in his review.

 

[TLS Guy]

I don't think this is a fair assessment at all and I Think you missed the point of this product. It's designed as a 2CH solution for those that can't place subs at separate locations in their room. RBH did NOT Intend this to be a fullrange speaker that people would also add separate powered subs. The fact that you can bi-amp this system and adjust bass to taste with their own DSP amps with PEQ is where a solution like this really shines. If you want a multi-ch system with separate powered subs, don't buy the bass modules and use the very competently designed satellite speakers as LCRs as James mentioned in his review.

I get the point. The problem is a passive crossover at 100 Hz. That doesn't work.

 

[gene]

I get the point. The problem is a passive crossover at 100 Hz. That doesn't work.

In a closed loop system with no bass management it works just fine as James reported running these as fullrange towers.

 

[TLS Guy]

In a closed loop system with no bass management it works just fine as James reported running these as fullrange towers.

It is not a s good as you think it is. If you put that crossover under the o-scope it would be a horror show. I would bet that the DC resistance of that LF choke is out of sight for another thing. The distortion it will create will be off the clock.

I have personally been down that road, and it is truly a horror show if you look into it rigorously.

I am not alone in believing that passive crossovers below 350/400 Hz region are to be absolutely avoided. I personally have a rule, that below 400 Hz is active.

Even then, as Raymond Cooke taught me that even at 400 Hz, you need added components to deal with the impedance/phase problems.

My family room speakers are threeways, with the bass mid cross at 400 Hz, and the passive crossover is complex with a high component count for the issues created by a crossover at 400 Hz. It all came together, but it is a challenge that magnifies the lower the crossover. I can tell you that the wire gauge and size of the inductors is significantly larger then what I saw in the picture Shady showed.

Lastly there was a missed opportunity, as the form of that enclosure looked ideal for a transmission line, rather than an ABR design with a sixth order roll off.

 

[shadyJ]

I can tell you that the wire gauge and size of the inductors is significantly larger then what I saw in the picture Shady showed.

The pasive bass module has its own filters that are not shown in the review. The inductors in the bass modules are much larger then the ones shown. The crossover network we do show is just for the bookshelf speaker portion, the 61-SF.

 

[AcuDefTechGuy]

I am not alone in believing that passive crossovers below 350/400 Hz region are to be absolutely avoided. I personally have a rule, that below 400 Hz is active.

The 61-SF (bookshelf cabinet sans the bass cabinet) has crossover frequency point of 2700Hz (which is the same XO point as the $12K Status Acoustics Voce Fina bookshelf that Gene absolutely loved).

Status Acoustics Voce Fina Bookshelf Speaker Review

Review: The Status Acoustics Voce Fina Bookshelf is one of the finest sounding speakers we’ve heard or measured. It’s a two-way design featuring SOTA drivers and a cabinet made out of solid granite.

www.audioholics.com

So for MOST people, they would just buy the 61-SF/R bookshelf and buy their own separate subwoofer.

But are you saying that all passive speakers, including towers like the Revel Salon2 (passive XO 150Hz), Focal Utopia (passive XO at 80Hz), should have the bass XO frequency point above 400Hz?

Revel Ultima Salon2 loudspeaker Measurements

Sidebar 3: Measurements My estimate of the Revel Ultima Salon2's voltage sensitivity was 86dB(B)/2.83V/m. This is slightly lower than the specified 86.4dB but within experimental error of that figure. The speaker's impedance (fig.1) drops to between 3 and 5 ohms between 17Hz and 600Hz, but as...

www.stereophile.com

The KEF Reference 201/2 bookshelf was considered to be one of the best speakers in the world by many people with almost textbook-perfect measurements, and it had the passive XO at 145Hz.

The KEF Reference 207/2 passive tower was also considered to be among the best, and the XO was at 120Hz.

KEF Reference 201/2 loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

KEF Reference 207/2 loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

 

[gene]

It is not a s good as you think it is. If you put that crossover under the o-scope it would be a horror show. I would bet that the DC resistance of that LF choke is out of sight for another thing. The distortion it will create will be off the clock.

I have personally been down that road, and it is truly a horror show if you look into it rigorously.

I am not alone in believing that passive crossovers below 350/400 Hz region are to be absolutely avoided. I personally have a rule, that below 400 Hz is active.

Even then, as Raymond Cooke taught me that even at 400 Hz, you need added components to deal with the impedance/phase problems.

My family room speakers are threeways, with the bass mid cross at 400 Hz, and the passive crossover is complex with a high component count for the issues created by a crossover at 400 Hz. It all came together, but it is a challenge that magnifies the lower the crossover. I can tell you that the wire gauge and size of the inductors is significantly larger then what I saw in the picture Shady showed.

Lastly there was a missed opportunity, as the form of that enclosure looked ideal for a transmission line, rather than an ABR design with a sixth order roll off.

Again you made assumptions without knowing all of the facts or considering the application of the design. This is a dangerous thing to do in any field of discipline, especially when it comes to audio.

I spoke to Shane Rich from RBH Sound who is an extremely seasoned and competent loudspeaker designer and he said that a lower crossover point is better for this particular speaker given the low placement of side firing 8” drivers (for better bass) and to provide best integration with the 6.5” driver/s from the satellite module. Bookshelf speakers on stands are quite frequently crossed over to subwoofers at 80Hz and even lower as I also alluded to in a prior post. This is meant as a closed loop fullrange sub/sat system with the convenience of maintaining a smaller footprint by not having to place additional subs at different locations.

Yes, it requires a bigger inductor which costs more, but they spend more to do it right. Attached is a picture of the crossover used in the 88-MS bass module.

The filters are effectively 1st order within an octave or so of the crossover point, then transition to second order. Using the lower crossover point also reduces the chance of noticeable phase shift in the vocal region, which would be more apparent with a higher crossover point—especially given the side-firing 8” woofers. This is one of the reasons the speakers image so well.

There’s nothing wrong with designing a speaker that uses a higher crossover point between the woofers and midrange/midwoofer, but according to Shane, for the 61SFM/R, the 100Hz crossover provides the best overall performance. Since the crossover is low order, the phase shift is minimal, and the 8” drivers actually still have usable output beyond 200Hz, ensuring ample dynamic range.

I updated the written review with this image and small passage for clarity.