Ascilab A6B Speaker Review

[AsciLab]

This is what I asked in my previous post
The first batch of the enclosure was made from a material largely composed of Aluminium Hydroxide.... I wonder now about the final version ?? !

Post in thread 'Ascilab A6B Speaker Review' https://www.audiosciencereview.com/...ascilab-a6b-speaker-review.69864/post-2535000

Yes. Current version is the final version.

 

[Matias]

Amazing speaker! Endgame material for 99% of us.

Personally I love the waving surround of the woofers and passive radiators. I am a "form follows function" guy, and to me, this is as nice as looking at an F1 car designed by Adrian Newey, with all the curves and sculpted angles to maximize performance. Huge pride of ownership!

 

[totti1965]

This is a review, listening tests and detailed measurements of the Ascilab A6B Stand-mount speaker with Purifi woofer and passive radiators. I purchased this from the company. The US cost is $1,955 each. Price varies in different countries due to tariff, local taxes, etc.
View attachment 515071
Please excuse the tapes. They are holding the magnetic rings in for shipping. I plan to sell these speakers after review so wanted to keep them in as new condition. On that front:

NOTE: My company, testedaudio.com, is the exclusive distributor for Ascilab products in North America. While objective tests remain the same as for any other speaker, subjective remarks may have business bias.

The A6B manages to act serious and stately at the same time. The rounded corners and invisible fasteners give it an elegant look. And the solid weight, an impression of quality.

I am not a fan of the wrinkles in the Purifi woofer surrounds. However, in the A6B when seen in normal lighting, they mostly disappear so were not an issue for me. The review picture however, highlights them to the max.

Speaker has dual Purifi passive radiators on opposing sides and are a nice indicator of when the speaker is being pushed by their excursion.

The bottom of the speaker is lined with some kind of neoprene which I much appreciate as it acts as some level of damping. To wit, I did not have to employ my elastic material for its measurements on top of Klippel Near-field scanner.

Ascilab A6B Speaker Measurements
As usual, we start with our all important, anechoic "CEA/CTA-2034" standardized frequency response and directivity measurements:
View attachment 515074
We have a very nice on-axis response (black). There is a bit of a drop in bass but then again, it extends way below to nearly 30 Hz with reasonable output!

The early window, and for that matter, sound power, track the on-axis extremely well indicating good directivity which we will examine more later.

We can see the bass extension comes from passive radiator tuning being on the low side:
View attachment 515075
The peak is around 40 Hz. As noted, resonances from the woofer is highly controlled. And given the fact that we don't have a port, there is not much to worry about with respect to enclosure resonances bleeding out. You pay a lot more for the radiator as opposed to just a port but this is the benefit it brings.

Early window sum looks very good, encouraging a room without much "treatment:"
View attachment 515076

With the resulting prediction of in-room response being what we look for:
View attachment 515077

Beamwidth is highly controlled, all the way to upper registers, courtesy of computer optimized waveguide:
View attachment 515078
The small penalty there is narrower beam width which translates into more focused imaging and less diffusion. Don't treat the side walls as to let that do its thing to widen the source image.

View attachment 515079

Vertical directivity is what it is for a 2-way speaker:
View attachment 515080

Stay at the tweeter axis.

Let me give you my usual distortion charts and then something new:
View attachment 515081
View attachment 515082

I have been on a mission to better correlate distortion measurements to audibility. Here, I could hear the start of very low frequency distortion at 96 dBSPL and heard the speaker nearly completely run out of excursion at 101 dBSPL. How can we better figure out from the graphs. Check this work in progress:
View attachment 515083
These are THD% levels charted below 200 Hz. That is where I heard the distortion. Above that, we are overdriving the speaker anyway relative to music.

We see a more or less plateau above 100 Hz indicating we have made the right choice regarding cut off at 200 Hz.

Below that we see different slopes in distortion. We see two distinct new distortion sources coming into play which I have marked as secondary and tertiary. I have placed a circle at the knee of those events. What this says is that you can play down to 42 Hz at 96 dBSPL whereas if you crank up to 101 dBSPL, you best stop at 65 Hz! This matches my hearing of the sweeps where I heard slight distortion at the very start of the 96 dBSPL sweeps. Whereas with 101 dBSPL, that lasted quite a lot longer and at much higher levels of audible distortion.

Going the other way, if you are playing at 81 dBSPL, you can essentially take advantage of the full response down to 30 Hz. We will see if this and the above prediction proves to be the case in listening test section.

Assuming above is correct, you don't need a subwoofer for 81 dBSPL and possibly 86 dBSPL. Above that, a subwoofer would be needed for those playback level and the frequency for that crossover is on the chart.

Finishing our measurements, we see some traces of resonances in waterfall graph:
View attachment 515084
Step response of the woofer is very smooth/clean:
View attachment 515085

Edit: impedance and phase:
View attachment 515092

Ascilab A6B Listening Tests
I paired the A6B with Topping LA90 amplifier which has modest amount of power. I did this to see how much power is needed given the fact that the sensitivity of A6B is a couple of dBs lower than average. I was pleasantly surprised that in near and mid-field listening, there was plenty of power available, albeit with one channel being driven.

First impression was quite a surprise: there was impressively clean and deep bass even in tracks that don't sport that spectrum! Research indicates 30% of our enjoyment comes from bass and there is no better example of this. The extra warmth, especially when it is this clean, balances tonality and creates butterflies in your stomach. I am not used to such a compact speaker being able to deliver such a bass.

I quickly skipped to my reference track for deep bass. This sized speakers either faintly reproduce the sub-bass, or distort it at slightly higher levels. The A6B in sharp contrast, reproduced the low energy like it was a full range speaker!!! It is one thing to see frequency response down to nearly 30 Hz, it is another to experience it with real music.

Excited, I cranked up the volume and bam! Massive distortion set it, just like the 101 dBSPL. You hear a static and see the dual radiators try to detach themselves as the fly out left and right! Crank it down a bit and you get a bit of roughness in bass. A bit more and you are back in business.

Note that the above test track has some of the lowest frequency energy track I have. On music with milder version of it, the A6B produced clean and authoritative bass that I could feel in my stomach (from 2 meters/6 to 7 feet away) and feel the air brushing against my face! I could get to mild distortion with cranking up the volume up again but not as bad as my reference track.

With general music tracks, no worries where there whatsoever with bass distortion and frankly any distortion. The high frequency notes would stand out in the midst of bass notes like nobody's business. Even tracks I have that don't sound very good on speakers (I use them for headphone testing), sounded nearly excellent here! The rest, wow, I kept smiling in disbelief! This is the most perfect speaker I have heard in this size. It just can't blast out its beautiful very low frequency beyond medium levels of loudness.

I am stunned....

Of course, at no time did I feel the need to EQ anything.

Nicely so, very little vibration was coupled to my desk where I had it -- unlike many speakers that uncover all kind of resonances in this setup (my far field listening space is down).

Imaging is rather focused as predicted. You hear the sound come from a circle close to the speaker.

As a side effect of my testing in near and mid-field, these speakers will also make an excellent studio monitor. I checked for horizontal directivity and it is excellent across 2 to 3 chair widths. Even after that, the drop off in high frequencies is rather small.

Conclusions
What a shame that I have started to sell these speakers and hence, my personal experience may not be trusted much. If you at all value my ethics, I am telling you, this is a speaker you have to experience. It will easily blow away any expectations you have.

Going into this review, I was kind of depressed. I an not into, "more expensive parts mean more performance" as some of you no doubt know. Those parts have pushed the price of this speaker rather high. What Ascilab has done with its tuning to deliver very low bass response that is ultra clean, is what justifies its cost. Yes, laws of physics can't be broken. It can't shake the house but if you are just a hair less power hungry than I am, you will be fully satisfied without having to mess with subwoofers and such.

As noted, I would give the A6Bs a serious consideration for mixing and mastering in smaller rooms. Pair it up with an ultra quiet amplifier like I did and you don't have none of the hiss issues of active monitors.

Please note that as of this writing, there is no production available of the A6B. Earliest time is May which means we will get them in June. I am going to put up my pair on Tested Audio but I have to say, I am so tempted to just keep them for myself! They are that good.

Needless to say, I am going to recommend the Ascilab A6B speakers. Objectively and subjectively, they have left me without pants.
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As always, questions, comments, recommendations, etc. are welcome.

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Hello @amirm,
Thank you for this extremely interesting study using the Klippel system!

What if the distortions that came into play at exactly 100 dB to 101 dB are caused by the Topping amp?
With 83 dB sensitivity per Watt per Meter you need about 64 Watt for 101 dB Sound pressure (8 Ohms).
The Topping has about 41 Watt at 8 Ohms and 70 Watt at 4 Ohms.
With an approximation of 6 Ohms in the very relevant frequency range of about 40 Hz the power capability of the Topping LA 90 is about is about 50 Watt.

So the Topping PA 90 reaches his very limit if you want to squeeze out 101 dB of these speakers and may be the reason for the Bass distortions.

Would be interesting to see how the speakers would play with a more powerfull amp. Perhaps: more relaxed at 101 dB?

 

[Raiju]

What are the main differences with the C6B?

 

[Matias]

A lower bass extension.

 

[Matt_Holland]

It will be interesting to see the distortion profile of the S6B which uses the larger PRs.

 

[FTB]

Research indicates 30% of our enjoyment comes from bass and there is no better example of this.

Hi @amirm ,

I'm interested in reading about this, do you have any link of a study ? Found nothing.

Thanks

 

[capslock]

Hello @amirm,
Thank you for this extremely interesting study using the Klippel system!

What if the distortions that came into play at exactly 100 dB to 101 dB are caused by the Topping amp?
With 83 dB sensitivity per Watt per Meter you need about 64 Watt for 101 dB Sound pressure (8 Ohms).
The Topping has about 41 Watt at 8 Ohms and 70 Watt at 4 Ohms.
With an approximation of 6 Ohms in the very relevant frequency range of about 40 Hz the power capability of the Topping LA 90 is about is about 50 Watt.

So the Topping PA 90 reaches his very limit if you want to squeeze out 101 dB of these speakers and may be the reason for the Bass distortions.

Would be interesting to see how the speakers would play with a more powerfull amp. Perhaps: more relaxed at 101 dB?

Amir wrote that he brought out the LA90 for listening. I'm sure he has a dedicated and more beefy amp for the Klippel.

 

[Everett T]

Hi @amirm ,

I'm interested in reading about this, do you have any link of a study ? Found nothing.

Thanks

Did you search AES white papers?

 

[capslock]

It is interesting to see the 86 dB/1 m distortion which is perfect and then the 96 dB/1 m which is far from. I am currently running a pair of R3 Meta and have not gotten around to integrating the subs. They don't go nearly as deep, and I'm sure their woofer is not optimized for high excursion, but they seem perfectly adequate in my roughly 60 m² (and 2.6 m high) living room. But then, what I consider loud listening is about 70 - 75 dB at the listening position, and I measured peaks of 83 dB at 1 m from each speaker with a calibrated sound level meter. This is reverberent field, so if I took them outside with the same setting, they'd probably measure lower.

So if other people are like me, these AsciLabs might be perfectly adequate without subs even in larger rooms, at least as you don't try to correct for suck-outs. Now for those who prefer to use subs, a closed box version would be highly desirable.

 

[trevor_bartram]

BBC engineers dreamt of this speaker in the 1960s. The Xover photo shows many parts, ala LS3-5A, would the frequency response be seriously degraded by fewer parts? My Debut 2 DB62s have only seven parts.
Are there Purifi papers that detail the steps they take to get performance? Low distortion, wideband woofers. Low leakage auxiliary bass radiators. I assume Purifi has patents that stop others using the technology.
This speaker is outwardly similar to the Radiant Acoustics Clarity 4.2 just measured by Erin. The 4.2 is a little cheaper.

 

[capslock]

BBC engineers dreamt of this speaker in the 1960s. The Xover photo shows many parts, ala LS3-5A, would the frequency response be seriously degraded by fewer parts? My Debut 2 DB62s have only seven parts.
Are there Purifi papers that detail the steps they take to get performance? Low distortion, wideband woofers. Low leakage auxiliary bass radiators. I assume Purifi has patents that stop others using the technology.
This speaker is outwardly similar to the Radiant Acoustics Clarity 4.2 just measured by Erin. The 4.2 is a little cheaper.

The 4.2 uses the 4 in Purifi, but there is also a 6.2 that uses the same size woofer. A 4.2 minus the passive radiators might be an even better solution for those with subs.

 

[trevor_bartram]

I have to wonder if this would have been better served with ports than PRs. PRs are excursion limited, where ports are mostly limited by how much movement the air can do before it turns turbulent.

Great results at normal listening levels though.

PRs create 12dB/octave rolloff. Ports 18dB/octave rolloff.

 

[JohnnyNG]

Wow - awesome. This was my "dream speaker" when it was first discussed in their main thread long ago. I've since gone a different route via DIY but I suspect I would not have been dissappointed!

 

[JohnnyNG]

I have to wonder if this would have been better served with ports than PRs. PRs are excursion limited, where ports are mostly limited by how much movement the air can do before it t

The Purifi woofers are almost impossible to design with ports. The port probably needs to be 16 inches long.

Or very narrow. PR is the obvious choice for a design like this.

 

[Everett T]

PRs create 12dB/octave rolloff. Ports 18dB/octave rolloff.

PRs 36, ported 24

 

[Sokel]

I'm sure he has a dedicated and more beefy amp for the Klippel.

This one:

Review and Measurements of Behringer A500 Amplifier

This is a review and detailed measurements of the Behringer A500 "Reference" Power amplifier. I purchased this unit on suggestions from members from Amazon for just $199 including Prime shipping. Being targeted at the pro market, this is rack-mount unit with heft heatsinks on each side...

www.audiosciencereview.com

About -67dB THD+N but good enough for the task.

 

[trevor_bartram]

PRs 36, ported 24

36 & 24 what?

 

[kharan]

There's a pretty large low frequency extension between Ascilab's measurements (April 2025) and ASR's measurements.

If I take the 100 Hz at the reference level, then -10 dB is at ~33 Hz with Amir's measurements, whereas -10 dB is at ~29 Hz with Ascilab measurements. Alternatively, at the same 30 Hz frequency, Ascilab's measurements are a few dB higher (-14 dB for ASR, -9 dB for Ascilab). Isn't the Klippel NFS system supposed to get rid of this level of uncertainty or are there some different settings (smoothing?) at play?

 

[JohnnyNG]

PRs 36, ported 24

Right - PR is not "sealed", it's bass-reflex.