Radiant Acoustics Clarity 66 Speaker Review

[pma]

Except that a sealed speaker gives more output than ported at frequencies well below the port tuning - the only 2nd order roll off wins at low frequencies well.

Exactly. And the cone excursion is much lower below the resonant frequency.

 

[capslock]

Given the size of this port, you almost need a football to shove in there to block the port.

A softball will do. Besides, the plugs for my R3 Meta are already the size of tennis balls.

 

[henz]

Bonus question: do you have a distortion measurement of the 6.2 or 4.2 similar to the one on page 31 of the deep dive? I still think one of the smaller models might be a better fit for me, unless the the improvement in midrange distortion by the alu cone is substantial. Unfortunately, all I have at this point is Erin's measurement, and I don't think his microphone and preamp are good for measuring low low distortion (there is a discussion on diyaudio about his mic).

I don’t believe we have those measurements, no, sorry. But I would expect the 66 to have substantially lower distortion especially in the midrange mostly due to the two woofers sharing the load.

 

[Lars Risbo]

I like to ask Mr Risbo if he has a speaker or piece of hifi, or listening experience that set him on this path in life?

My father did DIY speakers when I was a toddler. Big 100L boxes with 12” Peerless and 96dB sensitivity. I still have one of those boxes and there are paintings inside from me standing there as a 3 year old. He also did diy electronics and a gramophone. My mothers oldest friend was professor in acoustics and signal processing and he also did even more clever audio with active speakers and had access to the large anechoic chamber at DTU (been there as a kid too). Actually, his M.Sc thesis project was to measure the chamber (build in 1964). He became my thesis supervisor for master and PhD. I guess all that got me locked into audio engineering and signal processing. Besides this i loved music and played piano and for the last 50 years cello.

 

[Cogito]

Probably a primary criteria among other factors.
People usually turn the volume down because of unpleasant sounding peaks - due to distortion, and end up at modest listening levels.
Clarity at reasonable loud volume is addictive!

I see frequency responses, impedance numbers, efficiency ratings, crossover points, driver size, etc., but with a few exceptions (KEF being one), I rarely see distortion values listed in published specifications in the marketing materials. I wonder why? Perhaps in real-world listening, it doesn't really matter since such distortions are typically masked by the sound? Of course, if a speaker is poorly designed and/or driven beyond it's design limits, distortion could certainly an issue.

In MY experience, I have NEVER had to turned down the volume down due to "unpleasant sounding peaks" even at unreasonable levels (95+/- dB), even with my 85 dB efficiency bookshelf speakers. Or maybe, I've simply gotten lucky with my speaker choices over the past 47 years I've been in this hobby?

 

[henz]

I see frequency responses, impedance numbers, efficiency ratings, crossover points, driver size, etc., but with a few exceptions (KEF being one), I rarely see distortion values listed in published specifications in the marketing materials. I wonder why? Perhaps in real-world listening, it doesn't really matter since such distortions are typically masked by the sound? Of course, if a speaker is poorly designed and/or driven beyond it's design limits, distortion could certainly an issue.

In MY experience, I have NEVER had to turned down the volume down due to "unpleasant sounding peaks" even at unreasonable levels (95+/- dB), even with my 85 dB efficiency bookshelf speakers. Or maybe, I've simply gotten lucky with my speaker choices over the past 47 years I've been in this hobby?

I think you are, perhaps, misunderstanding the effect of distortion on the sound you’re hearing. We’re not necessarily talking about harsh sounds or even distortion as you know it from amps or a turntable. In a speaker, I’d say it presents itself more like a smearing or veiling of the sound, more than unpleasant sounds you can easily identify.
It’s always there in the background in most speakers, quietly ruining your enjoyment of the music.

I’d liken the experience of hearing a distortion-free speaker to the relief you get when a noisy A/C unit running in the background is FINALLY turned off. To a lesser degree, of course, but I’d say it’s a similar feeling.

You end up listening to the speakers a lot more, for longer periods of time, and experiencing way less fatigue. Plus, you can turn up the volume a lot more and sometimes hardly notice it, because the distortion is normally the thing telling you that you’re playing (too) loud.

As to your question to why most manufacturers don’t show their distortion measurements… it’s probably because they’d rather you didn’t see it

Edit: I see now that my colleague also replied. Fortunately, we agree!
Sorry for ganging up on you

 

[smokeymackinsey]

I see frequency responses, impedance numbers, efficiency ratings, crossover points, driver size, etc., but with a few exceptions (KEF being one), I rarely see distortion values listed in published specifications in the marketing materials. I wonder why? Perhaps in real-world listening, it doesn't really matter since such distortions are typically masked by the sound? Of course, if a speaker is poorly designed and/or driven beyond it's design limits, distortion could certainly an issue.

In MY experience, I have NEVER had to turned down the volume down due to "unpleasant sounding peaks" even at unreasonable levels (95+/- dB), even with my 85 dB efficiency bookshelf speakers. Or maybe, I've simply gotten lucky with my speaker choices over the past 47 years I've been in this hobby?

From my (personal) perspective it could be multiple aspects. In the amplifier market, distortion is a solved problem by now. Before that it was an important spec to compare performance and make different amplifiers comparable. Therefore low distortion figures, have become a standard for spec sheets of amplifiers. Up until today, we are chasing the last couple % of THD and and SINAD improvements in this market, to have your product stand out.
Distortion is not a solved problem in speaker and driver design though. Looking at distortion levels, we are talking about magnitudes more distortion in speakers than in amplifiers. Lots of manufacturers don't have the means to properly measure it and therefore cannot publish it. Secondly, even if you have the means to measure it and can't compete on that front and nobody else does it either, why publish them at all?

We - as in Nordic Hi-Fi/Radiant Acoustics - would welcome distortion measurements to become a standard in the industry, as it is just as important as frequency responses, impedance numbers, efficiency ratings and all the other specs you mention. It is just not one that is common yet - and not instantly translatable into a real life listening experience. We are hoping that other manufacturers will also focus on this area, as you can make a true difference in sound quality there and move forward the hi-fi industry as a whole.

Further, distortion is part of the sound, it is not masked by it. I think parts of the discussion here is about semantics. The word distortion implies effects like clipping, saturation or "overdrive" - if you want to take distortion of guitar amps as an analogy. Of course most speakers don't clip or distort in that way, unless driven way past their limits. So we completely understand the feedback from many members of this forum, that have not experienced distortion in their systems - even if the speakers could have significant distortion measurements.

What distortion in the context of this review and the measurements means, is rather what I would describe as a "dynamic coloration". It is measured as frequency and volume dependent change of the sound after all. My office is right by a hifi shop and I can A/B compare the Clarity 66 with other popular brands every day. The lack of this "coloration" has to be heard to be understood well - and it is quite addicting at that!

Edit: @henz , looks like you beat me to an answer haha

 

[Drengur]

@Lars Risbo as a representative of one of your former colonies this makes me very happy: "All prices [...] include everything — shipping, duties, and VAT. No hidden fees. You also get 30 days to return your order for a hassle-free experience." I am sure this will suffice as reparations for the pain learning Danish in school has brought our proud people.

All jokes aside, how will you manage? Are you sure this would include barren islands in the middle of the frozen Atlantic? If this is true, the price is very attractive. As usually shipping+import fees+taxes could amount to double the price.

 

[henz]

@Lars Risbo as a representative of one of your former colonies this makes me very happy: "All prices [...] include everything — shipping, duties, and VAT. No hidden fees. You also get 30 days to return your order for a hassle-free experience." I am sure this will suffice as reparations for the pain learning Danish in school has brought our proud people.

All jokes aside, how will you manage? Are you sure this would include barren islands in the middle of the frozen Atlantic? If this is true, the price is very attractive. As usually shipping+import fees+taxes could amount to double the price.

A few countries are excluded for these reasons of course… any customers in these countries can still contact us, though, and we’ll see what we can do.

 

[Lars Risbo]

@Lars Risbo as a representative of one of your former colonies this makes me very happy: "All prices [...] include everything — shipping, duties, and VAT. No hidden fees. You also get 30 days to return your order for a hassle-free experience." I am sure this will suffice as reparations for the pain learning Danish in school has brought our proud people.

All jokes aside, how will you manage? Are you sure this would include barren islands in the middle of the frozen Atlantic? If this is true, the price is very attractive. As usually shipping+import fees+taxes could amount to double the price.

i am versus sorry for your sufferings and our imperialism

I enjoyed my visits to your islands when i was 6 and 18 years old. first time in an old expedition tent without a bottom and a water stream that got attracted to our tent. living in the clouds most of the time. I just loved it. my trusted job was to keep the matches dry.

 

[capslock]

i am versus sorry for your sufferings and our imperialism

I enjoyed my visits to your islands when i was 6 and 18 years old. first time in an old expedition tent without a bottom and a water stream that got attracted to our tent. living in the clouds most of the time. I just loved it. my trusted job was to keep the matches dry.

Just out of curiosity, are you two talking about the Faroe islands?

 

[Lars Risbo]

yes (I am at least )

 

[markk]

I have to chime in with agreement on the idea that distortion is under-appreciated. Well before there is obvious perceptible distortion, there is a region where the character of the low frequency spectrum is changed. The graphs I took below are from over a decade ago, and don't represent cutting edge motor/driver technology. But they illustrate some really important points about distortion at the low end.

Both of these units are MLTL towers, one driven by a somewhat pedestrian GR research 5" driver. The other, a Scan 8554, which, in its day (and, well, even now to some extent) a very solid 8" performer. They are both driven by a three tone burst centered around 50hz to a level of 86dB at 0.5m.

The m130 appears to be operating around its Xmax limit, given the 3rd order family of distortion products is around -20dB. All you should be hearing is is the fundamental group at 50 hz, but you are getting audible harmonic at 100, 150, etc all the way out to 300 or so. This doesn't sound like distortion. How do I know this? Because at the same time I'm running these graphs, I am actually listening to these test tones. One of the cool things about running these rather old school test tones is you can hear the character of the output change. Before it sounds like distortion, it just sounds, well, different. Less clean. But you can be fooled. If it's reproducing the fundamental of a kick drum in the 50's, it doesn't sound bad, it doesn't sound like distortion. In fact, some would say it's "richer."

But it's still not right. If you have a bookshelf two way with a typical 5-6.5" driver, your output signal will be more like the m130. No matter how audiophile you think you are. And this can't be overcome by the latest DAC with a 120dB SINAD and a Purifi amp...

If you look at the SS 8554 8" unit, it's notably better. Still about 3% second order products, but 3rd order and higher are way, way lower. Plus, there are no higher order products (the m130 has some mild chuffing going on. It's 60-80 dB below the fundamental, but still very audible being 5 or so octaves away from the fundamental.)

The point being most loudspeakers with small LF drive units color the LF sound with even relatively ordinary in room spl levels. Now you might be thinking that newer drivers have markedly better distortion profiles. While drivers have improved, they have not improved to the point where one 5-6.5" LF drive unit won't color LF output at reasonable listening levels.

The purifi seem somewhat remarkable in that the two 6.5" drivers, which have an Sd comparable to an 8" driver, seem to have a LF distortion profile comparable to a 10 woofer. This is definitely unusually good since it allows a two way narrow tower to provide full range performance similar to a 3 way with a good 10" driver.

 

[Drengur]

He is talking about the Faroes, I can tell from the weather-description. I am talking about Iceland. Everyone wants to come here, no one wants to ship speakers here.

 

[suttondesign]

I’d liken the experience of hearing a distortion-free speaker to the relief you get when a noisy A/C unit running in the background is FINALLY turned off. To a lesser degree, of course, but I’d say it’s a similar feeling.

You end up listening to the speakers a lot more, for longer periods of time, and experiencing way less fatigue. Plus, you can turn up the volume a lot more and sometimes hardly notice it, because the distortion is normally the thing telling you that you’re playing (too) loud.

this. I play the cadentia 3 louder. the chatter kind of thing I was accustomed to at louder levels is no longer present.

 

[Adamant11746]

Wow! I voted Great when I read the initial review, but it was a close decision coming down to stunningly low distortion vs decent but not exemplary performance in other areas. I happened to click on the review again and saw the updated measurements, which changed my opinion from "great in some areas, decent to good in the rest" to "OMG, they got that level of performance out of 2 moderately sized bass drivers?"

I've been reading ASR (and to a lesser extent following other objective reviewers) for a while, and these speakers stand out as some of the only models with such deep and low distortion bass. There are some that come close, like the Kef R11 and Revel F328be (which have similarly low distortion but slightly less extension), but without spending much more there are very few competitors that go this low. There are always going to be tradeoffs, like the directivity and treble in the Clarity 66's case, but the strengths of this design seem almost totally unique.

 

[see_no_evil]

this. I play the cadentia 3 louder. the chatter kind of thing I was accustomed to at louder levels is no longer present.

Distortion in speakers is also very apparent if you are used to listening to low-distortion headphones/IEMs.

 

[markk]

One more point about the graphs above. Since the M130 is down 20dB in its third order family, it's basically at Xmax, as I mentioned. The other way of interpreting this is that this is as loud as the M130 will play. Push it any louder and it will fall apart rapidly.

This is in contrast to the 8554. Its third order distortion products family is almost 50 dB down while generating the same spl. So the 8554 can still play louder, significantly so. It's cleaner at the same spl level and can play the transients. It's not really near Xmax at all. If you have a deep bass transient of 35hz, with the 5" driver, well, all you will hear are the 70, 105, 140... overtones if the average spl level is 85. It will sound like bass, but not the 35hz bass that was on the source material. The 8554 will have some increased distortion with transients to be sure, but it will be cleaner and play louder.

 

[Lars Risbo]

Wow! I voted Great when I read the initial review, but it was a close decision coming down to stunningly low distortion vs decent but not exemplary performance in other areas. I happened to click on the review again and saw the updated measurements, which changed my opinion from "great in some areas, decent to good in the rest" to "OMG, they got that level of performance out of 2 moderately sized bass drivers?"

I've been reading ASR (and to a lesser extent following other objective reviewers) for a while, and these speakers stand out as some of the only models with such deep and low distortion bass. There are some that come close, like the Kef R11 and Revel F328be (which have similarly low distortion but slightly less extension), but without spending much more there are very few competitors that go this low. There are always going to be tradeoffs, like the directivity and treble in the Clarity 66's case, but the strengths of this design seem almost totally unique.

thanks!

My guess is that Clarity 66 beats R11 on bass distortion at least if we level normalise. First of all R11 has a 5dB shelv down bass response so the output in the 30-60Hz range is lowered by 5dab compared to the midband and the 96dB or 102dB SPL are mid band averages. A 5dB reduction in output reduces distortion significantly- this is why a level normalised test would be most fair (like the CEA sub test). R11 is also tuned higher so the distortion explodes sooner.

Finally, our published bass distortion measurements show lower distortion than what the Klippel gets and it stays very low to just below 30Hz (port tuning).

It is challenging to measure distortion at both very low frequency and high SPL. I had to develop a super slow exponential sine sweep to capture this.

Look at eg 30Hz where R11 approaches only -10dB THD and this is at its F10 so ‘only’ 92dB SPL. The 66 is at -40dB THD at 30Hz for more SPL (my measurements though) which is quite insane.

compared to 66 measured on the same machine. note the 30Hz point: about the same SPL as the R11 102dB plot but way lower distortion.

 

[Coltr@ne]

@Lars Risbo
Forgive the stupid question—I’ve read through all the Purifi datasheets on the site—but could you tell me which innovation you consider the most significant in achieving such low distortion for your drivers?