This review and test originally appeared in Australian Hi-Fi magazine, one of What Hi-Fi?’s sister titles from Down Under. A full bench test was also performed by Newport Test Labs and is also included here. Click here for more information about Australian Hi-Fi, including links to buy individual digital editions and details on how to subscribe.
Someone once said that imitation is the sincerest form of flattery that mediocrity can pay to greatness (and no, it wasn’t Oscar Wilde; the derivation is uncertain). And in this regard we’d note that Richter’s most successful model, the ‘Wizard’, may be the only Australian loudspeaker design that has ever been outrightly copied.
The ‘knock-offs’ were marketed under the name ‘Lizard’, though the only thing that the real Wizard and the copy Lizard had in common was their general appearance (the drivers and crossover were completely different) and their one-letter-changed model name. But it was ‘imitated’ because Richter’s Wizard design was not only the best-selling Australian speaker on the market, but also the best-selling loudspeaker in its price category.
When we reviewed the latest iteration of the Wizard earlier this year (the Wizard Series 6Plus, so yes, a design still going strong), we suggested that there were so many significant changes over the previous Series 6 version that Richter could have called it a ‘Series 7’ model.
Well here we go again. The same could be said of these new speakers from the Sydney-based company, which update the company’s classic Merlin bookshelf design from Series 6 to ‘S6plus’ status.
Design & drivers
Type: Two-way vented bookshelf, bass reflex with port tuning
Tweeter: 25mm soft-dome w. neodymium magnet
Bass/midrange: 165mm composite paper cone
Quoted frequency response: 44Hz–30kHz (–6dB)
Sensitivity: 88.5dBSPL @1M @ 2.83V
Nominal impedance: 6 ohms (min. 4.6 ohms)
Dimensions (hwd): 320 × 220 × 289mm
Weight: 7.3kg (each)
As anyone acquainted with the Merlin model will see from the images accompanying this review, the Merlin S6plus are two-way bookshelf designs that look so similar to the previous Merlin S6 that it would be very easy to confuse the two. (Luckily, Richter has now discontinued the older model.) But the new version actually has both a different tweeter and a different mid/bass driver.
The obvious visual difference between the two tweeters is that the new Merlin S6plus’s 25mm neodymium-powered soft dome unit has a shiny edge trim around its mounting plate. The more significant difference, however, is that the new one has, says Gosnell, “improved sensitivity, a lower resonance frequency and double the power-handling ability, resulting in a new level of clarity and engagement”.
It is, in fact, precisely the same tweeter found in the company’s larger, pricier Wizard S6plus. And I guess it isn’t even a ‘new’ tweeter because it was actually originally developed for the Wizard Series 6 ‘Special Edition’ introduced in 2023.
Just as the Merlin S6plus share a tweeter with the latest Wizard, they also share a mid/bass driver. Indeed, it is almost exactly the same as the Wizard’s, though of course the Wizard packs two of them into each cabinet. Multi-purposing the same driver makes a lot of sense because the more drivers you order from a manufacturer, the lower the cost of each one, and it’s buying drivers in bulk this way that helps Richter keep the retail prices of its speakers so low.
You’ll notice that I wrote ‘almost exactly the same’; the Wizard driver has an eight-ohm voice coil while the new Merlin’s has a four-ohm one. Naturally, this is down to the two voice coils in the Wizard being paralleled, resulting in the crossover network seeing an impedance of four ohms.
As for the mid/bass driver’s construction, its cone uses a unique pulp – a mix of paper, hemp (non-smokable), kapok, wool and engineered chemical fibre that is made extremely stiff in order to minimise cone breakup and roll-off resonances. Gosnell says the driver in the Merlin S6plus has a newly redesigned magnetic circuit to help further linearise the driver’s frequency response, particularly across the 1kHz region. There has supposedly also been a 10% reduction in nonlinear distortion compared to the driver used in the previous model. This, says Rodgers, “delivers a smoother, cleaner performance where it matters”.
One thing I’ve often failed to mention when reviewing Richter loudspeakers is that the company has started paying a lot more attention to ‘fit ‘n’ finish’ than it ever did in the past, an example of which is that new silver trim around the tweeter mount. The mid/bass driver also benefits from being fitted with far superior ‘dress rings’ than before, so they don’t merely hide the hardware that keeps the driver firmly fixed to the baffle, but also make it look better than ever if you prefer to listen to music without the speaker grilles in place.
The provision of the dress ring meant that I could not establish whether the 16.5cm diameter Richter claims for the S6plus’s driver is the measurement for the overall chassis or the distance between the mounting holes. What I can tell you is that the Thiele/Small diameter (the measurement used by speaker designers to determine cabinet alignments) is 13cm, giving an effective cone area (fs) of 133cm².
The speaker grille attaches to the baffle magnetically and features absolutely huge rectangular cut-outs to ensure minimum diffraction for those who like listening with them in place. It’s worth noting here that Richter supplies its grilles for free; some manufacturers charge extra for them!
The Merlin S6plus’s bass-reflex port is located on the rear of the cabinet, above the single pair of gold-plated multi-way speaker terminals. The port is a 10cm-long, 5cm-diameter, shiny, black plastic extrusion that is flared only at its exit. If you typically prefer the sound of bass from a sealed enclosure, Richter supplies two foam bungs (each 7.5cm long and 5.2cm in diameter) which can be used to block the ports and convert the naturally vented enclosure to a sealed one (more about this later on...).
Although the Merlin S6plus cabinet is listed as being 22cm wide in Richter’s specifications, this doesn’t tell the whole story because the sides slope from being that width at the front to being just 21cm at the rear. This helps to control internal resonances that can be present in cabinets that do have parallel sides.
Richter’s specs are also a little misleading where cabinet depth is concerned, because while they correctly state it as ‘289mm including grilles’, they fail to mention that you will need to allow a further 2.5cm of space at the back to accommodate the long-ish terminals.
Listening sessions
First up on the audition running sheet for the Merlin S6plus was an oldie from Steely Dan, 1980’s ‘Gaucho’, and I knew I was in for a treat right from the moment the first notes of Babylon Sisters burst forth from them. There was a liveliness and presence to the delivery that I find is the hallmark of all great-sounding loudspeakers. When I hear this, I know straight away that the speakers are doing exactly what they are supposed to do.
The precision of the drums on the intro might have you wondering whether Steely Dan’s infamous $150,000 drum machine is keeping the beat, but actually it’s none other than Bernard Lee ‘Pretty’ Purdie, who was not only more precise than a drum machine but also the inventor of the famous Purdie Shuffle (triplets against a half-time backbeat) which are present further on in this track. You won’t hear Purdie again on this album, though, as there’s a different drummer on every track! In fact, more than 61 musicians contributed to it, including Michael Brecker (the sax on Glamour Profession) and Mark Knopfler (the solo on Time Out of Mind).
The balance of sound the S6plus delivers on Babylon Sisters is perfect across all fourteen instruments and seven vocalists, including Fagan himself. The Merlins reproduced even the tiniest details fantastically well, which really says something considering there are hundreds of tiny musical details on this track alone. It’s not for nothing that ‘Gaucho’ was nominated for the ‘Album of the Year’ and ‘Best Pop Performance’ Grammy Awards in 1982, and took home the Grammy gong for ‘Best Engineered Recording’.
Hey Nineteen, which follows, allowed me to hear the Merlins’ deep-bass capability, thanks to the brilliant bass lines from Walter Becker, which are recorded front and forward since they really drive the track. Sure, there isn’t the low-frequency level, nor the depth, you get from a pair of Wizards, but the Merlins come close — very close! Indeed, I was impressed by how much bass Gosnell has been able to extract from a relatively small driver in a small cabinet.
I also used this track to see which alignment I preferred – sealed or bass reflex – and I have to say that for me and my listening room, the former won out. The sealed alignment allowed me to push the cabinets right back against the rear wall to maximise bass output, and while this trick usually has adverse effects on stage depth and imaging, I remained perfectly happy with both.
Skipping past the title track (for which Becker and Fagen were successfully sued by Keith Jarrett, on account of it being pinched from his Long As You Know You’re Living Yours), I listened to Time Out of Mind to hear not only Knofler’s guitar but also Hugh McCracken’s.
Although I was very pleased with the high-frequency sound I had heard so far throughout my auditioning, I decided to listen to the string sound of the Melbourne Symphony Orchestra playing with Elton John on his album ‘Live in Australia’, not least as it features several songs from his second, self-titled album (my favourite Elton album), although sadly not First Episode at Hienton. The Merlin S6plus rose to the challenge, with smooth, lush string sound and excellent tonalities, not least with the fabulous flute solo, which sounded exactly as a flute should.
Of course, I then had to play my favourite Elton album, not least to catch up with First Episode, which was good because I could then hear how well the Richters handled the Moog lines from Diana Lewis on this track and also on The Cage. The tweeters handled the Moog’s super-highs brilliantly well, including the panned effects. Elton also used a real orchestra on this album, and the clarity and texture of the strings were once again fabulous through the Merlin S6plus.
To audition female vocals, it was back to Oz again with Missy Higgins’ debut album, ‘Sound of White’. The Richters delivered her voice with almost disconcerting realism, not least because her vocals were recorded so cleanly. In fact, all the instruments were beautifully captured, and equally beautifully delivered by the Merlins, whether it was Martin Tillman’s cello, John Patitucci’s double bass or Higgins’ own piano (though it’s actually sometimes Jamie Muhoberac playing the piano).
Verdict
The design brief for the previous Merlin S6 was that the speakers should deliver sound quality that was ‘engaging, musical and inspiring’, and in my review of them some years ago I concluded that Dr Gosnell had achieved these aims.
I’m not sure what his design brief was for this ‘plus’ version, but I do think that they are even more engaging, more musical and more inspiring than their predecessors, such that they’re by far and away some of the best-sounding speakers I’ve heard in their price bracket.
Laboratory Test Report
Readers interested in a full technical appraisal of the performance of the Richter Merlin S6plus loudspeakers should continue on and read the LABORATORY REPORTs. Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested. Steve Holding, Newport Test Laboratories
The in-room frequency response measured by Newport Test Labs for the Richter Merlin S6plus is shown in Graph 1 above. The response was measured using pink noise as the test stimulus, and the representative trace shown is the average of nine measurements taken in a grid fashion, with the grid’s central part being on the tweeter axis and its upper limit being 30kHz.
You can see that the frequency response is very flat, particularly across the midrange region, where from 170Hz up to 4kHz it is contained within a 2.5dB envelope, meaning it is essentially 170Hz–4kHz ±1.25dB. From a musical perspective, that range is from a little below ‘middle C’ to a bit beyond the highest ‘C’ on a piano keyboard.
But even if we extend our frequency compass even further, the Merlin S6plus’s response remains superbly flat, extending from 80Hz to 30kHz ±3dB. While Newport Test Labs performs this test in a room, it does not use any boundary reinforcement, hence the low-frequency limit. If you moved the speakers closer to a rear wall, the low-frequency response would extend lower, which is obviously what Richter itself did to obtain its low-frequency specification of 44Hz.
The lift in the response between 4kHz and 15kHz is only slight, in the order of 2.5dB, which I don’t think would result in any ‘brightness’ per se but would instead ensure clarity. This is, of course, an on-axis response, so you could easily reduce the high-frequency level by listening slightly off-axis.
Graph 2 above shows the on-axis high-frequency response of the Merlin S6plus, this time measured using a gating technique that delivers extreme frequency precision and replicates the response that would be obtained if the speaker were measured in an anechoic chamber. It also extends the upper measuring limit to 40kHz.
The increased precision again shows the linearity of the response across the midrange region (though this is necessarily limited to 500Hz, due to the measurement technique), and you can see here that the broad high-frequency rise revealed in Graph 1 is actually the sum of three small increases in the tweeter’s output at 4.5kHz, 5.5kHz and 7kHz, plus a significant rise at 10kHz.
You can see too that the tweeter’s response extends out to 35kHz before rolling off sharply. The two traces show the performance with (red) and without (black) the grille in place, revealing that the grille is almost completely acoustically transparent. The only real anomaly occurs at 7.5kHz, but a 3dB dip at that frequency would not be audible anyway.
The Merlin S6plus’s low-frequency performance, as measured by Newport Test Labs, is shown in Graph 3 above. It was obtained using a near-field technique that also replicates the response that would be given in an anechoic chamber, so once again there is no boundary reinforcement. Also, you should ignore the trace above 200Hz, as the near-field technique is not accurate above this frequency for a driver with a diameter of that used in the Merlins. (The ‘glitch’ at 100Hz is due to the test equipment switching from one measurement range to another, and should also be ignored.)
The blue trace on Graph 3 shows the bass driver’s roll-off when the bung is fitted to the bass-reflex port, effectively sealing the enclosure. You can see that it rolls off very smoothly below 100Hz at an almost-perfect 12dB per octave: ‘textbook’, in other words. When the port is open, the driver’s low-frequency output rolls off much faster, at 24dB per octave (black trace), but naturally the output of the port (red trace) compensates for this, as the graph shows.
You can also see that the port’s output has been engineered to peak rather lower in frequency than usual, occurring at around 40Hz rather than up at 50Hz where we would typically expect. This has undoubtedly been engineered to improve bass extension.
Newport Test Labs’ measurement of impedance and phase is shown in Graph 4 for both the ported (red trace) and sealed (blue trace) alignments.
The trace glitches at 100Hz, 1kHz and 10kHz are caused by the test equipment switching ranges, as noted earlier, but the one at around 260Hz is likely a cabinet resonance – but it is so tiny it would not affect sound quality.
The traces show that the Merlins’ impedance stays below eight ohms from 90Hz up to 500Hz, a region where there’s significant musical energy, so we would prefer to treat this design as having a nominal impedance of four ohms, rather than the specified six ohms. Although the minimum impedance within the audio band is exactly 4.6 ohms as claimed in the specifications (at 170Hz), the impedance drops lower at frequencies below 20Hz. This drop, however, is of no concern – we mention it only because it’s visible on the graph.
Graph 5 is a composite of several response measurements made by Newport Test Labs. The pink trace shows the pink noise response above 900Hz, which is closer to what the human ear would hear than the gated anechoic response shown by the mauve trace. This graph extends the measurement of the port’s output (red trace) and shows some high-frequency bleedthrough around 1–1.5kHz, but as it’s more than 15dB down, again it should not be audible (and will not be there at all if you block the port).
Newport Test Labs reported the measured sensitivity of the Merlin S6plus as being 85dBSPL at one metre for a 2.83Veq input, which is significantly lower than Richter’s specification of 88.5dBSPL albeit fairly close to the figure we would expect from a small-ish driver in a relatively small cabinet, so Richter obviously used a different measurement technique. (The average of all consumer hi-fi speakers is around 87dBSPL.) The below-average sensitivity means you should err on the more powerful side when selecting an amplifier, although any well-designed amp rated at 60 watts per channel into eight ohms (or more) would ensure realistic listening levels in a typically sized room.
Overall, the Richter Merlin S6plus are excellent designs that exhibited superior performance in Newport Test Labs’ tests, particularly in terms of midrange linearity and high-frequency extension.