Radiant Acoustics Clarity 66 Speaker Review

[dfuller]

oh yes, an active with a PTT10 can go deep with good headroom. would make it sealed and EQ it, F3 at 20Hz should be feasible.

Not far off what PDP has done, no?

 

[markk]

While interesting, that would be a wildly different speaker from a design standpoint. We wanted to make something that could actually easily fit into most “normal” living rooms (with existing gear) and still provide deep, clean bass and a truly distortion free mid-range.

I think the 66s truly challenge the status quo of what a relatively small, passive floor standing speaker can do when it comes to performance and distortion… without costing an arm AND a leg. But then I am not really objective

I get it. There is a niche for this form factor, a taller narrow passive unit. It's what a large number of old school audiophiles are looking for to match up with the their high end amp and interconnects. And, in this niche it has outstanding performance and top tier bass performance

 

[pma]

There is a niche for this form factor,

I would go for it, but the price is too high, to me.

 

[see_no_evil]

But home HiFi fans just won't adopt the technology. It's been that way for so long. It's a shame.

Maybe just maybe reliability and modularity (and not just performance alone) are still the concerns to people spending their money.

 

[markk]

Not far off what PDP has done, no?

Interesting

Not far off what PDP has done, no?

Interesting. I would really like to see Amir test the MUM-10's. Anyone want to send him one?

Still, probably doesn't appeal as much to the niche that the Radiant Acoustics is targeting.

High end audio evolves slowly. 20 years ago I designed a 2 way speaker around the Seas DXT. The whole point was an exercise in improving the DI of the standard 6.5" two way speaker. I thought at that time a plethora of manufacturers would follow with different OEM waveguide/tweeter combos. I stepped away for a while (life) but have recently started doing a little DIY. In that interval the pro sound manufacturers have taken this idea and ran with it. Waveguides with HF units are the norm to improve the DI. But if you look at the high end OEM loudspeaker driver manufacturers, I'm suprised at the lack of WG tweeters. I thought there might be an explosion in the two decades I wasn't paying attention, but that didn't happen. There are more WG tweeters around, but they are more boutique and DIY types. Some for sure, like the Satori WG based units. But not what I was expecting. OEM manufactures are still pumping out tweeters with a flat 104mm faceplate and some esoteric dome material. (Though I did get sucked into buying some beryllium dome tweeters in a moment of DIY weakness...)

I do think the niche for built in active speakers with low distortion and uniform DI characteristics is growing. Just more slowly than I thought it would among audiophiles.

 

[MCH]

would be nice but active speakers are sadly not an easy sell to the hifi market. they eliminate expensive cables and several other electronics boxes. somehow consumers don’t value all the electronics inside active speakers

I do, but I don't want to have to ship a 40 kg, 4000 eur worth huge fragile item internationally for repair. Not everybody lives close to a place where these things could be repaired.

 

[pma]

Impedance is typical at minimum of 4 ohm:

This will make hard times, to some amplifiers. As well as the area near 60Hz (phase). EPDR would show it even more clearly.

 

[Gremlins]

10k ?? .. not impress
I'd rather spend that cash into a pair of genelec 8361a that would cost exactly the same price for a linear frequency response, amps, digital, DSD etc etc

I still don't understand what argument would be on table to purchase 10k hifi tower speakers these days against 8361a where you just need a streamer/preamp and you running

 

[markk]

10k ?? .. not impress
I'd rather spend that cash into a pair of genelec 8361a that would cost exactly the same price for a linear frequency response, amps, digital, DSD etc etc

I still don't understand what argument would be on table to purchase 10k hifi tower speakers these days against 8361a where you just need a streamer/preamp and you running

You're just not the market niche.

If said audiophile owns a 10k esoteric amp they really like, well, changing their mind is like trying to convince someone to change their political party.

I think a manufacturer over the long term probably would do well to target both markets as there is money to be made in both niches. As long as they can have better performance in their niche than the other manufacturer, they will do ok. There is still money to be made in this style of speaker if they can do it better than the competition.

 

[Marc v E]

And £6998 in the UK according to the Hifi News review in the August 2026 edition.

For comparison, my ATC SCM40 Active are £8500 a pair.

I can’t see that review online yet, but the earlier one of the 4.2 model is here:-

Radiant Acoustics Clarity 4.2 loudspeaker

To call the Clarity 4.2 ‘petite’ is no understatement, as this second loudspeaker to be introduced by Radiant Acoustics boldly puts the ‘book’ back into ‘bookshelf’. Moreover, the cabinet, just 260mm high and 164mm wide, still manages to host a full four drive units. This Danish company only...

www.hifinews.com

Note the exceptional bass extension, and the trade-off with sensitivity below 80dB!

You know what keeps me wondering?

Why would anybody pick the 66 over the 4.2 or 6.2 with subs?
The 4.2 is 2500 euros a pair. 6.2 is 4000. With 2 to 4 subs I think it could give an equal or better sound in a room. Or am I overlooking something?

 

[Matt_Holland]

That's a mistake. Again see my measurements of TAD and JBL and pay attention to response of those woofers as they roll down. There are break ups and resonances mixing with everything else resulting in chewed up response in critical area of 1K to 5 kHz. Using idealized drives in sims gives you highly misleading results. I much rather see a 3-way than any 2.5 way. It is a difference about reality vs theory....

I think you showed bad examples of 2.5 designs.
If the lower woofer is crossed with a steeper LPF slope it shouldn’t interfere in the mid-range.
The other benefit of 2.5 way is you can compensate for baffle step with the woofer instead of having to absorb all the unwanted (forward only) energy in the crossover.

There is another thread on here somewhere where Bruno addressed a few of us commenting on the decision for 2-way versus 2.5-way and he agreed that he could achieve a much better vertical dispersion, but he preferred to compromise that in order to get the crazy good distortion results and power handling.

Edit: I think it was Lars who commented, not Bruno. Apologies.

 

[DSJR]

I see that these use AMT tweeters. I remember hearing those many, many years ago and being very impressed; I didn't know they were still around. Just wondering about the bass-midrange: is it better to have 2 smallish wide-range drivers or larger bass and smaller mid? Is it just about having a nice, narrow cabinet? Anyway, I'd guess that these are hard to beat for £7k.

Am I talking out of turn to suggest a raft of Genelecs and Neumanns which are fully active, let alone many other passives recommended both here and by Erin (Ascilab, Audio First and so on)?

Apologies folks, but as soon as I saw the tweeter type used it rang pre-conceived alarm bells as so far on the few speakers I've heard with similar type of tweeters-with-cones, the timbres have never integrated properly to me, the sharply defined (or downright tinselly in bad-uns like Neats) top never properly matching the mids and bass. Things have moved on so far now, but properly implemented conventional tweeters may well have improved the vertical dispersion plot, as I see it anyway

 

[dfuller]

Apologies folks, but as soon as I saw the tweeter type used it rang pre-conceived alarm bells as so far on the few speakers I've heard with similar type of tweeters-with-cones, the timbres have never integrated properly to me, the sharply defined (or downright tinselly in bad-uns like Neats) top never properly matching the mids and bass. Things have moved on so far now, but properly implemented conventional tweeters may well have improved the vertical dispersion plot, as I see it anyway

I'm personally also not fond of AMTs, even in generally well-engineered designs they don't sound great IME. Kinda sandpapery quality to the lower treble...

 

[Matt_Holland]

Interesting

Interesting. I would really like to see Amir test the MUM-10's. Anyone want to send him one?

Still, probably doesn't appeal as much to the niche that the Radiant Acoustics is targeting.

High end audio evolves slowly. 20 years ago I designed a 2 way speaker around the Seas DXT. The whole point was an exercise in improving the DI of the standard 6.5" two way speaker. I thought at that time a plethora of manufacturers would follow with different OEM waveguide/tweeter combos. I stepped away for a while (life) but have recently started doing a little DIY. In that interval the pro sound manufacturers have taken this idea and ran with it. Waveguides with HF units are the norm to improve the DI. But if you look at the high end OEM loudspeaker driver manufacturers, I'm suprised at the lack of WG tweeters. I thought there might be an explosion in the two decades I wasn't paying attention, but that didn't happen. There are more WG tweeters around, but they are more boutique and DIY types. Some for sure, like the Satori WG based units. But not what I was expecting. OEM manufactures are still pumping out tweeters with a flat 104mm faceplate and some esoteric dome material. (Though I did get sucked into buying some beryllium dome tweeters in a moment of DIY weakness...)

I do think the niche for built in active speakers with low distortion and uniform DI characteristics is growing. Just more slowly than I thought it would among audiophiles.

The lack of WG tweeters in audiophile products is, I believe, because there is a myth that plagues the scene that says a WG is a horn and horns are bad. You can add it to the list of myths like EQ is bad, digital creates a stepped waveform, everything matters, 24/192 is clearly superior to 16/44, etc.

 

[kemmler3D]

the crazy good distortion results and power handling.

Yes, that seems to have been job #1 with this speaker, and well done. I can't recall seeing a cone speaker with lower distortion than this... maybe some horns can manage it.

 

[dfuller]

The lack of WG tweeters in audiophile products is, I believe, because there is a myth that plagues the scene that says a WG is a horn and horns are bad. You can add it to the list of myths like EQ is bad, digital creates a stepped waveform, everything matters, 24/192 is clearly superior to 16/44, etc.

To be fair, I'd rather a flat baffle than a badly designed WG and all the lovely diffraction effects they can cause...

 

[kma100]

I do, but I don't want to have to ship a 40 kg, 4000 eur worth huge fragile item internationally for repair. Not everybody lives close to a place where these things could be repaired.

You would just ship the amplifier section, correct? Not the entire speaker.

 

[markk]

To be fair, I'd rather a flat baffle than a badly designed WG and all the lovely diffraction effects they can cause...

I don't want to get into a tiff about this, but the evidence seems to support the opposite. Controlled DI has been shown to correlate with listener preference. The data for diffraction and listener preferences, last time I reviewed it, was mixed and minimal. Maybe I missed some more recent studies/data. Like I said, having been keeping up with recent AES stuff.

Diffraction effects certainly look bad on an FR chart. How audible they are is open to debate. I would take a smooth, monotonically decreasing DI than a low diffraction design with a wonky DI.

Of course, hopefully you can get respectable DI and try to minimize diffraction effects as well. I'm not suggesting going back to some of the terrible horn designs of the past but passing up a WG design because it has a moderate on axis only wobble at 15k is probably not the way to go.

 

[Matt_Holland]

To be fair, I'd rather a flat baffle than a badly designed WG and all the lovely diffraction effects they can cause...

Yes, but who’s talking about badly designed WGs? What you’ve described is a “horn”.

Plenty of good sounding speakers with flat baffles, but none that beat the directivity performance of one with a well designed waveguide. Don’t forget a “phase plug” if you want extended highs too!

 

[Matt_Holland]

I don't want to get into a tiff about this, but the evidence seems to support the opposite. Controlled DI has been shown to correlate with listener preference. The data for diffraction and listener preferences, last time I reviewed it, was mixed and minimal. Maybe I missed some more recent studies/data. Like I said, having been keeping up with recent AES stuff.

Diffraction effects certainly look bad on an FR chart. How audible they are is open to debate. I would take a smooth, monotonically decreasing DI than a low diffraction design with a wonky DI.

Of course, hopefully you can get respectable DI and try to minimize diffraction effects as well. I'm not suggesting going back to some of the terrible horn designs of the past but passing up a WG design because it has a moderate on axis only wobble at 15k is probably not the way to go.

I would also add to this that a waveguide can reduce or even eliminate cabinet diffraction effects. There seems to be no technical downside to a good tweeter waveguide.