Radiant Acoustics Clarity 66

[Lars Risbo]

They said it's a 2 way and not 2.5 Way so I posted a message on their video roughly asking :

I read on their website that crossover point is at 2.4kHz

Really curious as λ (wavelength in m) = c (wavelength speed propagation in the air at 20°C and 1013HPa of atmospherical pressure in m/s) / f (Frequency in Hz) = 343/2400 = 0.1429m => As 6.5" drivers measure 0.1651m, means the wavelength at crossoverpoint is roughly the same size as the driver, so between the top and the bottom of the driver, that Frequency should nearly cancel, but let's admit that's fairly ok (which is already not much honestly), the thing is that now there are two drivers doing the same, now it certainly gets worse I assume (Especially between 1 and 2.4kHz as at 1Kkz it still can cancel between the top of the top driver and the bottom of the bottom driver), that's why most of manufacturers make a 2.5 Way with the 2nd driver crossing at a different Frequency, preventing that problem.

So, I truely wonder how they deal with that, and I'm quite curious to see Klippel vertical off Axis measurements, which would most certainly pinpoint that issue and look quite bad.

saw your post on youtube and answered. It was a very conscious choice to run the woofers in parallel. A 2.5 way has a main lobe pointing down into the floor whereas this is straight ahead towards the listener. we avoid a low crossover frequency that would add more group delay compared to this 2 way configuration. The two woofers share the load also in the midrange which further lowers the distortion. The woofers can share the same cavity and we can use a single large port which reduces port loss compared to separate ports. The flip side is that the the usual vertical off axis nulls that any non coaxial speaker now extend down in frequency. However, another way to look at it is that it helps mitigate the floor reflection a bit. Again, it was a very conscious choice. Everything involves compromises that have to be made carefully.

 

[henz]

That's basic acoustics.

And that's why I'm kinda disappointed to see a presumed error (not much presumed, honestly, as they provided Horizontal but not vertical measurments, surprisingly) like this at this price-point.

I love PuriFi drivers, I think they bring lots of new technologies/Ideas and pushed it all the way, along with Kartesian in the industry, but if it's truely like this, it's a total joke, imho.

Of course it's not an error. It's a trade-off. The gains from designing the system like this far outweighs the small disadvantage it brings, which ends up really only being that any vertical measurements won't look as good. In real life listening scenarios, the fix for this is easy (and free): simply sit down and listen on axis. Then you'll get all of the advantages only.

 

[Lars Risbo]

Curious, would like to hear them. Wonder if the claimed reduction of distortion could also be obtained by high passing (80hz) a Clarity 6.2?

no, the 6.2 would still only have a single woofer playing midrange whereas the 66 has two sharing the load which lowers distortion. Secondly, it is extremely difficult to do a good integration with a sub and the 66 bass performance probably outperforms many subs.

 

[Paul7777x]

We'll make sure Erin gets a pair.

Great news. I’ve no doubt they are as excellent as the 4.2s and 6.2s are, but I do like to check measurements.

Especially since I landed here.

 

[LEA-Ebenisterie]

Of course it's not an error. It's a trade-off. The gains from designing the system like this far outweighs the small disadvantage it brings, which ends up really only being that any vertical measurements won't look as good. In real life listening scenarios, the fix for this is easy (and free): simply sit down and listen on axis. Then you'll get all of the advantages only.

Well gentlemen, thank you for explaining the whole thing. I wonder how it sounds honestly considering that trade-off. As you said it's a choice of compromizes, but I truely wonder the benefits of lowering distortion on an already top class driver on that matter ! Especially when the trade-off is risking to cancel that utterly important midrange region whenever you move a tiny bit on your chair (considering that your ears are generally farther than measurments done - I.e. 1m), the fact of moving up and down a tiny bit is actually truely increased the farther you move from the speaker, correct me if I'm wrong.

 

[Soniclife]

saw your post on youtube and answered. It was a very conscious choice to run the woofers in parallel. A 2.5 way has a main lobe pointing down into the floor whereas this is straight ahead towards the listener. we avoid a low crossover frequency that would add more group delay compared to this 2 way configuration. The two woofers share the load also in the midrange which further lowers the distortion. The woofers can share the same cavity and we can use a single large port which reduces port loss compared to separate ports. The flip side is that the the usual vertical off axis nulls that any non coaxial speaker now extend down in frequency. However, another way to look at it is that it helps mitigate the floor reflection a bit. Again, it was a very conscious choice. Everything involves compromises that have to be made carefully.

Very interesting speaker, the bass measurements are very impressive from such a compact speaker.

I'm sure lots of us would like to see the vertical response, even though we think we know what it will look like, are you able to share it?

What sort of listening tests were done before settling on this configuration?

D’Appolito is the normal way of doing this in a 2 way, what were the pros and cons Vs your solution?

FWIW I like the ribs on the front.

 

[dfuller]

I'm curious why the choice was dual-woofer 2 way rather than 3 way for the tower. Purifi is way better than most in terms of midrange distortion in a 2-way configuration, but I find it difficult to wrap my head around this being lower than a driver that isn't doing all that excursion at LF. Maybe the sensitivity was too low? Just a guess.

 

[Lars Risbo]

Very interesting speaker, the bass measurements are very impressive from such a compact speaker.

thanks

I'm sure lots of us would like to see the vertical response, even though we think we know what it will look like, are you able to share it?

horisontal polar: we need to work on a fixture lift it sideways up in 3.7m height.

What sort of listening tests were done before settling on this configuration?

yes, we listened and decided it was the right call to go 2 way.

D’Appolito is the normal way of doing this in a 2 way, what were the pros and cons Vs your solution?

D’Appolito would require a taller cabinet if the tweeter should sit in the conventional height.

I'm curious why the choice was dual-woofer 2 way rather than 3 way for the tower. Purifi is way better than most in terms of midrange distortion in a 2-way configuration, but I find it difficult to wrap my head around this being lower than a driver that isn't doing all that excursion at LF. Maybe the sensitivity was too low? Just a guess.

3 way is reducing IMD because the midrange woofer is not doing bass duty. however, that would leave all bass to a single woofer and we would not get our increased bass headroom. 2.5 way helps on the bass but like 3 way you have a crossover at a low frequency which adds more group delay (timing). Also, this delay makes the main lobe point downwards into the floor. The pure 2 way lowers the midrange distortion as well as bass distortion thanks to the load sharing and we have less group delay from the crossover. The vertical nulls might even be an advantage since the two woofers act as a line array and less sound bounces of the floor and ceiling.

 

[Lars Risbo]

Well gentlemen, thank you for explaining the whole thing. I wonder how it sounds honestly considering that trade-off. As you said it's a choice of compromizes, but I truely wonder the benefits of lowering distortion on an already top class driver on that matter ! Especially when the trade-off is risking to cancel that utterly important midrange region whenever you move a tiny bit on your chair (considering that your ears are generally farther than measurments done - I.e. 1m), the fact of moving up and down a tiny bit is actually truely increased the farther you move from the speaker, correct me if I'm wrong.

the sensitivity to listener height actually diminishes the long you sit away. the nulls are in specific angles and the change of angle is reduces and you move away. You need to hear them to try.

 

[dfuller]

3 way is reducing IMD because the midrange woofer is not doing bass duty. however, that would leave all bass to a single woofer and we would not get our increased bass headroom.

This, I assume, could have been solved with using a larger woofer, but then you still have the additional crossover with added phase rotation that can't be linearized out in passive crossovers.

An active design using FIR filters or the PSI-style cascading all-pass network could work here; I am thinking something along the lines of a PDP MUM-8 but with meaningful directivity control.

 

[Paul7777x]

Well gentlemen, thank you for explaining the whole thing. I wonder how it sounds honestly considering that trade-off. As you said it's a choice of compromizes, but I truely wonder the benefits of lowering distortion on an already top class driver on that matter ! Especially when the trade-off is risking to cancel that utterly important midrange region whenever you move a tiny bit on your chair (considering that your ears are generally farther than measurments done - I.e. 1m), the fact of moving up and down a tiny bit is actually truely increased the farther you move from the speaker, correct me if I'm wrong.

Actually as it is sound waves we’re talking about here, the further you sit from the source the less important it becomes. The sound will spread more as a widening, (from the source) cone like effect.

I can’t think of any way to keep a sound wave in free air from spreading. Certainly no way to make it converge to a smaller point?

 

[Paul7777x]

This, I assume, could have been solved with using a larger woofer, but then you still have the additional crossover with added phase rotation that can't be linearized out in passive crossovers.

An active design using FIR filters or the PSI-style cascading all-pass network could work here; I am thinking something along the lines of a PDP MUM-8 but with meaningful directivity control.

March Audio do something of this kind (that is a two way) using an 8 inch Purifi.

But so far as I know there are no Klippel measurements published yet.

I’d be interested to know what differences might be expected between the choice of an 8 inch or two 6.5 inch woofers.

Ps;

I’m trying to be educated here, not contrary

Ukkonen AWG Floor Standing Speaker (PAIR) – March Audio

The Ukkonen AWG is a floor standing speaker featuring state of the art drivers from Purifi and SB Acoustics with beautiful solid wood or painted cabinets. Class leading technical and subjective audio performance.

marchaudio.com

 

[dfuller]

March Audio do something of this kind, using an 8 inch Purifi.

But so far as I know there are no Klippel measurements published yet.

Ukkonen AWG Floor Standing Speaker (PAIR) – March Audio

The Ukkonen AWG is a floor standing speaker featuring state of the art drivers from Purifi and SB Acoustics with beautiful solid wood or painted cabinets. Class leading technical and subjective audio performance.

marchaudio.com

Oh I was talking about a 3-way design, not a 2-way. If you wanted to do all-Purifi, you could do that; 8 or 10 + 4 + 1. There are other options for non-purifi mid and tweeter though; Bliesma and SB Satori come to mind. PTT8 or PTT10 + M74 series (take your pick) + T25 series, or PTT8/PTT10 + MD60N or MR13TX + any of the TW29s.

 

[Paul7777x]

Oh I was talking about a 3-way design, not a 2-way. If you wanted to do all-Purifi, you could do that; 8 or 10 + 4 + 1. There are other options for non-purifi mid and tweeter though; Bliesma and SB Satori come to mind.

Cheers sir. I changed my post at the same time you replied. And I confused myself.

 

[Paul7777x]

Oh I was talking about a 3-way design, not a 2-way. If you wanted to do all-Purifi, you could do that; 8 or 10 + 4 + 1. There are other options for non-purifi mid and tweeter though; Bliesma and SB Satori come to mind.

Ps I have a very good (to my ears; never measured them) three ways using an eight inch, five inch and the venerable Scanspeak D2905/93000 tweeter.

I’ve loved them for years.

I’m hoping, and expecting, the 66 or the 6.2 or the SPK16 kit to comfortably outperform them.

 

[Paul7777x]

Just a thought.

But, a pair of 6.2s and a Lyngdorf TDAi 2210 is the same price as the 66 pair.

Add another thousand pounds for a pair of subs and the 66’s look expensive.

Unless you already have a high power, high quality amp naturally.

I’ve decided to second guess myself.

If I read the graph above correctly then the anechoic f3 is at 32Hz?

So in a room and even remotely close to a rear wall these may well be floorstanders that actually don’t need a sub.

Given enough horsepower. And that’s no longer expensive.

 

[Penelinfi]

Oh I was talking about a 3-way design, not a 2-way. If you wanted to do all-Purifi, you could do that; 8 or 10 + 4 + 1. There are other options for non-purifi mid and tweeter though; Bliesma and SB Satori come to mind. PTT8 or PTT10 + M74 series (take your pick) + T25 series, or PTT8/PTT10 + MD60N or MR13TX + any of the TW29s.

There's still this CLC 65 (is there even much advantage to the 4" vs 6.5"?)

 

[LEA-Ebenisterie]

There's also a good 3 way involving PuriFi drivers (+ SB Acoustics tweeter) made by Troels Gravesen :


http://www.troelsgravesen.dk/Purifi-6661.htm

 

[Juhazi]

Actually as it is sound waves we’re talking about here, the further you sit from the source the less important it becomes. The sound will spread more as a widening, (from the source) cone like effect.

I can’t think of any way to keep a sound wave in free air from spreading. Certainly no way to make it converge to a smaller point?

You forget the interferences from multiple drivers and edges. It is sad that we don't often see this effect visualized. Even a ripple tank shows it only for a single freq.

Here just a single midrange on-axis at different mic distance, spl normalized

 

[dfuller]

There's still this CLC 65 (is there even much advantage to the 4" vs 6.5"?)
View attachment 519425

I mean, I think the 4" might work better for a smaller WG, which generally means rather wider overall beam width. If you prefer that, cool.

(Personally I'd rather use a higher sensitivity 3" dome like a Bliesma M74S-6 - about the same cost as a PTT4M - if I was going for wider beam, it's something like 12dB more sensitive and matches better to other drivers in terms of sensitivity.)