{"id":24674,"date":"2020-11-20T12:34:32","date_gmt":"2020-11-20T10:34:32","guid":{"rendered":"https:\/\/www.hifi-advice.com\/blog\/?p=24674"},"modified":"2022-06-27T09:12:21","modified_gmt":"2022-06-27T07:12:21","slug":"rtfs-part2","status":"publish","type":"post","link":"https:\/\/www.hifi-advice.com\/blog\/review\/accessories-reviews\/tuning-tweaks-reviews\/rtfs-part2\/","title":{"rendered":"R.T.F.S. Sirrah – Part 2"},"content":{"rendered":"

Review samples supplied by R.T.F.S.<\/a>
\nRetail price in the NL including 21% VAT: 249,90 Euro per unit<\/h4>\n

After starting my assessments of the R.T.F.S. SiRRAHs at audio buddy Jeroen’s place<\/a>, this is the second installment of the SiRRAH review. My experience with these products actually started in 2018 as part of Ben van Leliveld’s AcousticMatters<\/a> service which resulted in a series of tuning sessions (see review)<\/a> and the installation of four R.T.F.S Big Block Bass Absorbers.<\/p>\n

While the R.T.F.S Big Blocks that Ben installed at that time much improved my room acoustics and turned them from unlistenable to very good, I never managed to fully linearize the Wilson Watt\/Puppy 8 speakers’ response over the entire frequency range using acoustic treatment. What I could<\/em> achieve was either very clean upper bass accompanied by a rapidly rolling off sub-bass or very deep bass accompanied by extreme dips and peaks in the mid-bass and upper bass. Ultimately, I accepted that the massive output of these speakers’ twin bass-reflex ports simply does not play ball with the acoustic peculiarities of my room. Since then, I’ve changed speakers twice, rotated the system position, and back again.<\/p>\n

After having been blown away by the Martin Logan ESL15A<\/a> and Magico S1 MkII loudspeakers I knew that I’d never get the Wilsons and the massive output of their twin bass-reflex ports to perform as linearly, not in this room. Via the Kroma Audio Carmens<\/a> which were much more well-behaved than the Wilsons and did many things better, ultimately, I settled on using Martin Logans and Magicos in a combined setup and this has been working very well for me ever since.<\/p>\n

There was only one small remaining problem: a flutter echo when using the Martin Logans. The issue was really only noticeable with certain music when the music consisted mainly of staccato beats and not much in the way of sustained sound, such as it is in many tracks by Janet Jackson or Michael Jackson. Interestingly, with the Magicos or any other direct-radiating speakers, the flutter echo was nowhere near as obvious which initially led me to believe that the issue had its roots in the speakers’ rear-firing sound. Thus, I set out to address the issue by means of treating the front wall.<\/p>\n

First efforts at treating the walls<\/h3>\n

Of course, I’ve always been aware of other detractive influences from the rear wall which in my setup of the last 2 years is only 60 cm removed from my ears. It’s just that I have never liked the side-effects of any materials that I tried on that wall in order to dampen or diffuse the reflections. I also tried adding damping and diffusion to the front wall but that also introduced unwanted side effects. For instance, the relatively simple GiK 244<\/a> wide-band bass traps deadened the sound too much and reduced the perceived treble response while Hofa Diffusers started adding very noticeable coloration when applying more than two of them. And when applied minimally, their effectiveness was only modest at best.<\/p>\n

\"\"<\/p>\n

In an effort to go all-out and betting on diffusion rather than absorption, I recently I tried 6 pieces of Resonator Stockholm Optiffusers. Constructed from expanded polystyrene foam, these 60 x 1200 cm units come highly recommended by acoustic experts and so I expected a lot. My samples were already painted and mounted into handy stackable wooden boxes by the previous owner meaning that I could get straight to the listening session without having to mount anything.<\/p>\n

Alas, while they most certainly took care of the flutter echo, they also introduced a boxy and nasal coloration in the midrange that was audible no matter where they were positioned. On the rear wall, this effect was most severe. I really wanted these diffusers to be the solution but, evidently, they were not the right way to address my issue.<\/p>\n

\"\"<\/p>\n

Long story short, because every measure that I took to treat my front and rear walls introduced unwanted side-effects I simply chose to live with the flutter echo and slightly too lively reflections.<\/p>\n

\"\"<\/p>\n

Could SiRRAHs be the solution?<\/h3>\n

At some point, I suddenly thought of the SiRRAHs. Since these panels are not only absorptive but also diffusers, they could be perfect for my application. Prior to this, I had performed tests using sofa cushions and this made it clear that I would need absorption and\/or diffusion in at least 3 spots on the front wall. I also experimented with these cushions on the rear wall where it would seem to be more logical given the proximity of the listening position to that wall. (60cm) However, using the aforementioned cushions in this location literally made me feel like my head was stuck in a pillow. So, I decided that I would treat only the front wall and contacted Farshid Shahlawandian of R.T.F.S. to ask for review samples. Farshid suggested sending 6 modules to enable more experiments and I am glad that he did because, as it would turn out, first, my assumption was incorrect, and second, I needed all 6 of them!<\/p>\n

\"\"<\/p>\n

Each SiRRAH unit has a flexible magnet glued to its wall-facing side to allow very easy application.<\/em><\/p>\n

\"\"<\/p>\n

The above flexible metal-impregnated plastic sheets with self-adhesive tape are attached to the walls as shown below.<\/em><\/p>\n

\"\"<\/p>\n

But during experimentation, they can be fixed using regular paint masking tape.<\/em><\/p>\n

\"\"<\/p>\n

SiRRAH Description<\/h3>\n

Uniquely, the smartly designed SiRRAH units have a twofold function. They combine the advantages of a diffuser with those of a bass\/midrange absorber. Given their relatively small size, they are remarkably effective as bass and midrange absorbers. Having made direct comparisons, I would say that a single SiRRAH is almost as effective as a single, twice-as-large, GiK 422 panel in terms of bass absorption.<\/p>\n

The SiRRAH modules achieve diffusion with their curvy shape which is painted with a proprietary coating that the company calls BreaCoat. This coating is only permeable to sound from the lower midrange down and thanks to this, the SiRRAH only acts as a diffuser in the midrange and treble. Medium and low frequencies penetrate the coating, where the core absorbs it. This is particularly important on the wall behind the speakers, as they emit more bass than high-frequency energy from the rear. This property allows the SiRRAHs to do their work while avoiding killing the ambiance as so many absorbers do.<\/p>\n

A diffuser is typically used to disperse incoming sound waves in order to enable clearer focus, better imaging, better soundstage layering and to eliminate (flutter-) echos. According to the manufacturer, most conventional diffusers only develop their full effect from a distance of approximately 2.5 meters. With the SiRRAH, however, R.T.F.S. has succeeded in reducing this distance to less than one meter and this allows the units to be placed very close to the listening position.<\/p>\n

<\/p>\n

Application with dipoles<\/h3>\n

From earlier experience, I already knew that you need to address reflection issues precisely in the right spots which is why the R.T.F.S. Sirrah panel’s 48 x 48 cm format is ideal. When using them directly behind the listening position one needs to take their depth of 23 cm into account but otherwise, they are pretty unobtrusive and in my view actually make for a tasteful work of art. To see how they transform a very empty room, see also part 1 of the SiRRAH review<\/a> done in audio buddy Jeroen’s setup.<\/p>\n

Normally with SiRRAH’s, one starts with two units, one left and one right at the points of the first rearward reflections. When the precise positions have been found you can work your way up using more SiRRAH modules to increase the impact until you get it just right.<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

The left speakers’ direct reflection point goes right into the RTFS Big Blocks.<\/em><\/p>\n

\"\"<\/p>\n

The outer edge of the speaker does aim straight at the bare wall. When standing in that position you can also clearly hear where the reflection stops.<\/em><\/p>\n

Preparation<\/h3>\n

I started by finding the first reflection points on the front wall, 3+ meters removed from the speakers’ stator panels. Especially on their rear end, Martin Logans are very beamy, following precisely the arc that the curved stators describe. Thus, it was easy to find the first direct reflection point, and from there, the adjacent sections.<\/p>\n

\"\"<\/p>\n

In-between the Big Blocks and the Audio Racks is where the first SiRRAH will be placed.<\/em><\/p>\n

\"\"<\/p>\n

Treating the front wall<\/h3>\n

Starting with the two most obvious positions behind the Martin Logans’ first rearward reflection points at ear height, the SiRRAHs greatly reduced the flutter echo while adding more clarity to and more distinct layering within the soundstage.<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

The quick result of the two SiRRAHs in this large space was so impressive that it made me lust for more. After unpacking two more units, I attached them right above the earlier two.<\/p>\n

\"\"<\/p>\n

The two extra panels provided a further reduction of overall reflections but it wasn’t quite as drastic as what the first two panels achieved. With the left and right sides so much improved, the remaining reverb that lingered in the center part of the room made it obvious that only the sides of the wall had been treated.<\/p>\n

\"\"<\/p>\n

Adding a SiRRAH panel right in the middle of the front wall at the same height as the left and right ones ended up visually half-behind the rack but very clearly reduced the flutter echo. While experimenting with the height, I found that the reflections started just above the highest component in the rack and extended to above the single SiRRAH.<\/p>\n

Adding another SiRRAH on top of the center one was the proverbial cherry on the pie, reducing the last remnants of the flutter echo while extending the soundstage further behind the speakers and making it appear more even-handed and more believable. Now, I also started hearing similar benefits as I observed in Jeroen’s setup – more isolated vocals with better focus.<\/p>\n

\"\"<\/p>\n

At this point, I entered a super-critical mode. Although the midrange and treble regions were amazingly clear and articulate, I simultaneously felt that the bass transients had become a little rounded. Could I be wrong about the placement of the left and right units behind the speakers? They are more than 3 meters removed from that wall so, theoretically, the rear wall should be an insignificant factor. Yet, I had this flutter echo to deal with.<\/p>\n

\"\"<\/p>\n

In an effort to re-balance the bass, I removed the four left and right panels while leaving the center ones in position. As hoped, this did indeed remove the roundness in the bass and reinstated the articulation and transient sharpness just the way I like it but it also very audibly brought back some of the flutter echo, this time clearly located in the left and right part of the room.<\/p>\n

This led me to conduct some more experiments with the horizontal positions while varying the height as well, made easy by the extra sheets that Farshid so kindly added.<\/p>\n

As it stands, the front wall exhibits three main issue areas. But the question that entered my mind was whether these should all be addressed on the front wall. The left and right ones are where the speakers beam rearward while the center position is where the forward-beamed sound ends up after being reflected off the back wall, focusing back onto the middle on the front wall.<\/p>\n

\"\"<\/p>\n

The final arrangement on the front wall<\/em><\/p>\n

I finally accepted that, while the center two locations offered clear benefits without introducing any unwanted side effects, the left and right locations behind the speakers were just not ideal. Although I had tried to avoid it for the aforementioned reasons, it seemed that the remainder of my reflections had to be taken care of via the rear wall.<\/p>\n

<\/p>\n

Also treating the rear wall<\/h3>\n

After finding the direct reflection positions and the range of the horizontal spread on the rear wall, I started by adding two SiRRAHs in the places where the reflected sound would directly reach my ears.<\/p>\n

\"\"<\/p>\n

Bull’s eye! Just like with the first two SiRRAHs on the front wall, these two on the rear wall made all the difference. Gone was the remaining flutter echo, replaced with much more order to the soundstage and a significantly better focus of vocals and other sounds that are recorded in mono. Now, the Logans were coming a lot closer to the reach-out-and-touch 3D imaging capabilities that many dynamic speakers seem to do so much more easily.<\/p>\n

\"\"<\/p>\n

But, as with the experience on the front wall, some residual lively reverberance was exposed now that the sides had been taken care of. It’s amazing how easily the ear can tell where a problem area is, once part of the issue has been dealt with. Adding a third SiRRAH in the middle evened out the reflected sound and provided a nice, uniformly behaving sound bubble. It was better but I wasn’t sure if this was the way to go.<\/p>\n

\"\"<\/p>\n

Although the advantage was great and the side-effect subtle, the centrally-placed SiRRAH did take away just a little bit of sparkle and liveliness.<\/p>\n

\"\"<\/p>\n

It was nothing like the effect of the couch cushions when I tested them in the same position but when adding another SiRRAH on top to make for three vertically-stacked rows, I did feel that there was too much damping going on behind my head.<\/p>\n

\"\"<\/p>\n

Because it looked so nice and because I just wanted to know, I proceeded by adding two more SiRRAHs but this confirmed that there was indeed an ideal number of units to use for this wall.<\/p>\n

Fine-Tuning<\/h3>\n

Knowing now that I needed two rows of two vertically-stacked SiRRAHs, it was only a matter of finding the ideal horizontal positions. After all, in their initial positions, the results in the left and right portions of the rear wall were amazing but that left me with a portion in the center that was still standing out by being too lively.<\/p>\n

In itself, liveliness can be nice, in some cases even essential. In this case, though, the experiments with the SiRRAHs have shown that the uncontrolled reflections also add blur and mess up the focus and other aspects of the soundstage.<\/p>\n

\"\"<\/p>\n

The grey rectangle on the wall is actually what I used as the projection area for the beamer when my setup was still rotated by 180 degrees. I never got around to painting it over and now I find that it actually enhances the artful presentation of the SiRRAHs.<\/em><\/p>\n

In order to find the ideal positions, I attached multiple fixation sheets closely together so that I could freely position the four SiRRAHs in any horizontal position. Then, the listening started.<\/p>\n

As I anticipated but had to try anyway, spacing them out further only increased the audibility of the uncontrolled reflections in the center area. But when moving them closer, all of a sudden I hit the jackpot. Boom! Even though there was still an amount of empty wall between the two stacks the size of a single SiRRAH unit, all of the perceived reflections in the center were gone. And along with it came even better focus and bass articulation.<\/p>\n

Wrapping it up<\/h3>\n

Since my issues were the result of using dipole loudspeakers in a room with two reflective walls, it had been more difficult than it normally would be to arrive at the ideal composition. But I also found it hugely interesting to hear the result of every step that I took. Essentially, Martin Logans are line sources. They are quite beamy but their curved stators do spread out the sound roughly over the width of a 3-person sofa. Although I initially thought that my flutter echo issue was caused by the speakers’ rear-firing sound, it turned out to be caused only by the sound coming from the front, spread throughout the room horizontally. Part of this sound bounced off the rear wall and right into my ears while another part of this sound (angled more to the sides) went past my ears and ended up on the front wall again, only to be reflected back at me, causing the flutter echo in the process.<\/p>\n

What I arrived at to effectively solve this, while improving many other aspects of the sound, was a mix of front-wall and rear-wall damping\/diffusion. The front wall (behind the speakers) ended up with a single row of two stacked units that took care of the part of the speakers’ forward-firing reflections after they had been reflected off the rear wall. Meanwhile, the rear wall (behind the listening position) ended up with two rows of two vertically-stacked units to take care of the part of the direct reflections.<\/p>\n

As it followed, the center part on the rear wall did not need any damping because the front wall already took care of that. And vice versa for the left and right sections on the front wall.<\/p>\n

\"\"<\/p>\n

There you have it: the final positions for the SiRRAHs on the rear wall.<\/em><\/p>\n

\"\"<\/p>\n

Conclusion<\/h3>\n

Please read this story as the adventure that it is, don’t let it discourage you from starting work on treating your own room. See part one of the SiRRAH review<\/a> for a much more common room and, consequently, a more typical solution.<\/p>\n

Given my unusual situation, the solution that I arrived at is perhaps also a little unusual. But the results are staggering and absolutely worth the effort. These include clearer bass with better articulation, deeper and more even soundstaging with clearer layering and much better focus. The real beauty of the SiRRAHs, as opposed to every other damping or diffusion product that I used so far, is that, when applied sensibly, they bring all the benefits without any negative side effects. That, and they look like beautiful pieces of art!<\/p>\n

\"\"<\/p>\n

Manufacturer’s Comments<\/h3>\n

A Schroeder Diffuser acts as a diffusor because the sound is reflected from it at different angles and at different times. This creates the huge sound field these diffusers are known for. That is very important in an opera hall. But it is a false hugeness in a listening room which has two big disadvantages.<\/em><\/p>\n

If you sit too close to that type of diffuser you can hear the different sound waves reflecting off it at different times. Depending on how deep the diffuser is the more distance it takes for these different sound effects to become a \u201ecloud of sound\u201c which creates a huge sound.<\/em><\/p>\n

That chopping of sound in the time domain, however, leads to much less focus. At first, it is impressive that the soundstage of the orchestra becomes so big. But then you realize that you cannot hear where the first violin is located exactly.<\/em><\/p>\n

More SiRRAH<\/h3>\n

R.T.F.S Sirrah – Part 1<\/a><\/p>\n

External Links<\/h3>\n

AcousticMatters website:\u00a0AcousticMatters<\/a>
\nR.T.F.S manufacturer’s website:\u00a0R.T.F.S.de<\/a>
\nDealer for the Netherlands: ListeningMatters<\/a><\/p>\n

\r\n
Related Posts<\/div>\r\n
\r\n\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n Network Acoustics origin Streaming Power Supply <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n XACT N1 Network Switch <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n PS Audio PowerPlant 15 and 20 <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n Silent Angel Bonn N8 Pro and Bonn NX Ethernet Switches and Genesis GX Clock <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n Network Acoustics tempus <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n Ansuz PowerSwitch X-TC3 and D3 <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n Mad Scientist Black Magic Ultra and Black Magic Gold <\/a>\r\n\r\n <\/div>\r\n
\r\n
\r\n \r\n\r\n \"\"\r\n\r\n <\/a>\r\n <\/div>\r\n\r\n \r\n Jorma Audio Unity Interlink, Power Cable, and Speaker Cable <\/a>\r\n\r\n <\/div>\r\n \r\n <\/div>\r\n\r\n