RBH R-515 on Audioholics Measurement Test Platform

The RBH R-5 and R-515 speakers were measured in free-air at a height of 7.5 feet at a 1-meter distance from the microphone, and the measurements were gated at a 8.5 millisecond delay. In this time window, some resolution is lost below 250 Hz and accuracy is completely lost below 110 Hz. All curves have been smoothed to a 1/12 octave resolution.

RBH R-5 (left) and R-515 (right) response curves

While there are some fluctuations in the above response curves, for the most part they are not bad. These are not the flattest frequency responses I have ever seen, but these are a $150/ea and $215/ea speakers, respectively, so perfection is not expected. For the R-5, one flaw that we see is a possible breakup mode that peaks at around 4.5 kHz which the crossover is not fully suppressing. This is likely the cause of the sibilance that I heard in some of the vocals. Something else to note in the directivity index of the R-5 graph is the evenness of the dispersion up until 10 kHz or so; from 1 kHz to 10 kHz, the off-axis response remains very stable and well-controlled. One interesting contrast that we see when we compare the R-5 and R-515 graphs is that the 4.5 kHz breakup peak seem to be inverted in the R-515’s direct axis measurement which speaks of some kind of phase cancellation. It only seems to occur on the direct axis response though, since it scarcely shows up on the other curves which all contain information about off-axis output. The R-515 seems to have somewhat hotter treble than the R-5, but those who worry that these speakers do not have an exact timbral match can relax; no horizontal MTM speaker has a timbral match with its bookshelf counterpart. The moment that you tip the bookshelf over and add another woofer on the other side of the tweeter, you have dramatically changed the directional behavior and thus the sound of that speaker. This affects all speakers of this design type.

For more information about the meaning of the curves in these graphs, please refer to our article Objective Loudspeaker Measurements to Predict Subjective Preferences.

RBH R-5 (left) and R-515 (right) Horizontal Responses +/- 100 degrees 

The above graphs depict the RBH Impression speaker’s lateral responses out to 100 degrees in ten-degree increments. In the R-5’s graph, we see that the lateral response mostly holds its shape at all off-axis angles. That means these speakers are very amenable to EQ’ing, where changes will be consistent across seating positions and acoustic reflections. In other words, EQ will have a predictable in-room response. The same isn’t as true of the R-515, at least in its horizontal orientation, because of the lobing patterns that the two woofers create at off-axis angles. Below 5 kHz we see nulls of cancellation formed at off-axis angles where the woofers are fighting each other for the same frequency but at different phases in the sound pressure wave. This happens with every MTM center speaker design where the tweeter is mounted between two woofers. While the R-515 has more irregularity for individual angle responses, we can see that overall it looks to have a flatter response than the R-5. The good news about that is that the irregularities of individual response angles can average out by the various acoustic reflections that ultimately combines at the listening position. This is why it is important to know how the speaker behaves off-axis; much of the sound we hear from an average domestic speaker system isn’t sound directly from the speaker itself but from reflected sounds off of in-room surfaces.

The above graphs show the same information as the preceding graphs but depict it in a way that offers new insight regarding these speakers’ behavior. Instead of using individual raised lines to illustrate amplitude, these polar maps use color to portray amplitude and this allows the use of a purely angle/frequency axis perspective. The advantage of these graphs is they can let us see broader trends of the speaker’s dispersion behavior more easily. I have included the graph of the R-515 in its vertical orientation for those who intend to use them as an LCR set. Of these responses, the best here belongs to the R-515 in its vertical orientation. The rate and shape of falloff is very consistent at off-axis angles. In fact, listeners could get a relatively full and listenable sound at a 60-degree angle off-axis, missing only some upper treble. The R-5 might have been the same except its tweeter output is comparatively recessed, so for a full sound using the R-5s, users will want to listen within 30 degrees of direct axis. When the R-515s are used in a horizontal orientation, the off-axis response starts to become very uneven past 20 degrees, so for the best sound from the R-515s when it is lying flat, try to stay within a 20-degree angle of the direction its tweeter is facing.

RBH R-5 (left) and R-515 (right) Vertical Responses +/- 100 degrees: 3D view

The above graphs depict the R-5 and R-515’s frequency response behavior on their vertical axis, where zero degrees is directly in front of the tweeter, negative degree values are below the tweeter, and positive degree values are above the tweeter. The vertical response isn’t nearly as critical as the horizontal response since human hearing isn’t as sensitive to reflections coming in from the floor and ceiling as it is to lateral reflections from side-walls. Furthermore, most people tend to listen at around the same height, unlike horizontal angles in which listening positions can be spread over a wide area. The dips in the high and low angles in the R-5 common to all conventional bookshelf speaker designs, although the R-5 fares better here than most. Most speakers start to exhibit these types of nulls much closer to direct axis than the R-5 does, but the R-5 offers a reasonably even response from 30 degrees below the tweeter axis to 20 degrees above it. You could place these speakers at positions a fair bit above or below listening position response and still get a reasonably full sound. For the best sound, however, try to use them at a height where the tweeter is level with the ear, but that isn’t as critical with these as it is with most speakers.

 R-515 Vertical Responses +/- 100 degrees: 2D view

The vertical response of the R-515 is excellent- when it is laying down horizontally. Of course, this measurement would be its horizontal response when used vertically/standing upright. And when standing upright, its true vertical response would be the ‘horizontal’ response graph shown previously. If that is all a bit confusing to you, just understand that the R-515 behaves much better when standing upright so that the drivers are lined up vertically. In that orientation, we get a nice, smooth response at every lateral angle, which is much more important to the end sound than up/down angles.

RBH R-5 Groundplane Bass Response

The above graph shows the RBH R-5 and R-515’s low-frequency responses that I captured using groundplane measurements (where the speaker and microphone are on the ground in a wide open area). RBH’s specifications of a +/-3dB window down to 57 Hz would seem to be a stretch by this measurement, but different measurement techniques can yield different curves, so I don’t believe they are trying to inflate the low-end extension on their product. By my measurement, I would give this speaker a -6 dB point of about 65 Hz. The difference between 57 Hz and 65 Hz is not consequential if a subwoofer is used, and I would recommend that a subwoofer be used with these speakers with an 80 Hz crossover or even higher frequencies in multiple sub setups where localization won’t be a problem. The nice thing about these measurements is that the low-frequency response is quite neutral for the most part, with hardly any boost in the low-end. Sometimes we see speakers that have inflated bass output around port tuning frequencies in order to give the impression of deeper extension than the speaker is actually capable of, effectively trying to substitute quality with quantity.

RBH R-5 (left) and R-515 (right) Impedance and Phase Response 

The above graphs show the electrical behavior of the RBH R-5 and R-515 speakers. RBH specifies the R-5s to be 8-ohm speakers, and that is a very conservative specification if anything. For the most part the impedance hangs well above 8 ohms, and all steep phase angles occur at high impedance points. The R-5s are a very benign electrical load, and any amplifier will be able to handle them with ease, even very low-budget AVRs. The R-515 is a bit different. Since the woofers are wired in a parallel circuit, the impedance within their range is halved. RBH specifies the R-515s as a 6-ohm speaker, and, as a nominal rating, I would say that is accurate. While this is not as friendly an electrical load as the R-5s, most AVRs should be able to handle these speakers. However, those who use the R-515s for the entire front stage speaker set may want something better than an entry-level AVR to drive these speakers.

RBH specifies the R-5’s sensitivity at 85.5 dB and the R-515 at 87 dB for 2.83v at 1 meter. For the R-5s, I measured 83.7 dB and the R-515s, 87.6 dB for 2.83v at 1 meter. This kind of difference isn’t surprising, as there are a lot of different ways to gauge sensitivity. My sensitivity measurements of the Impression speakers are not especially high or low, and they are about what I expected. The R-5 and R-515 speakers can get loud, but the R-5 speakers in particular will need something more powerful than a low-wattage amplifier to get loud. I think most people will be happy with them so long as they use an amplifier that has more than 10 watts of power capability.

Conclusion

RBH has launched the new Impression speakers in a crowded market for their price range, so we have to ask what do these speakers bring to the table and why should they be considered over the many other speakers in this range? Although imperfect, these are really good speakers for their price range. The R-5 does have some peakiness in mid-treble range that imparts some mild sibilance to ‘s’ and ‘sh’ sounds, but that can be alleviated by listening at a 20 degree angle off direct-axis or by using a parametric equalizer to reduce 4.5 kHz by 4 dB with a Q factor of 2.8 or so. Automated room correction equalizers like Audyssey or YPAO may also be able to smooth the response out as well. The lateral dispersion of the R-5 is good, but the lateral dispersion of the R-515 when used in a vertical orientation is superb; the better the lateral dispersion, the broader coverage that the speakers will have, so these speakers won’t have a small “sweet spot” where they only sound good in a single position. The R-5 and R-515 have a reasonably good dynamic range and can stay clean at loudness levels that would satisfy most people. Those aspiring for THX Reference levels in dedicated home theater rooms will want speakers that are more robust, but these RBH Impression speakers are more than capable for most users.

Outside of the performance front, there are the aesthetics of the R-5 and R-515, which are fine in the phantom black finish and amazing in the High-gloss Black. I want to emphasize how nice these speakers look for the cost in High-Gloss Black. I’m not sure that a nicer-looking speaker can be had at that pricing. The High-gloss Black finish is only a $25/ea surcharge for the R-5s and $35/ea for the R-515. Those who get the High-Gloss Black will want to handle these speakers with cotton inspection gloves to avoid visible fingerprints on the cabinet surface- it’s that nice. Regarding amplifier compatibility, the R-5 is a very friendly speaker that can run on any amplifier, whereas the R-515 is a bit more demanding but still wouldn’t be a particularly difficult load. The build quality is generally quite good for the price, with a well-conceived enclosure, beefy-looking drivers, and a neatly-arranged crossover.

If you think the RBH Impression speakers might be a good fit for your system, there is a 30-day in home trial where the speakers can be returned for any reason for a full refund (minus return shipping charges), so there is little risk in giving them a try. Buyers get a 5-year warranty with an option to extend with a fee. To sum up the R-5 and R-515 speakers, they are a very well-rounded speaker system for an extremely reasonable price, especially for High-Gloss Black speakers. In a crowded field of $300/pr. to $500/pr. bookshelf speakers, they are a solid choice.