AsciLab F6Bs Speaker Review

[OnAir]

I love the VESA mount and slim profile! @AsciLab I’ve seen your roadmap but are there any plans to offer a similar profile but with the better drivers of the c/a/s lines?

The C5Bs of the C line is now on sale in Korea.
32×16×15.5 cm

 

[ry_]

The C5Bs of the C line is now on sale in Korea.
32×16×15.5 cm

Thanks for the info! Thats good to know. Sounds like it’s definitely in the realm of possibility that there will be more sealed ones coming later if the C5Bs is already on sale in Korea! I may see if I can find a way to get a C5BS to California… I’m surprised @AsciLab hasn’t commented yet

 

[Dovydas]

Yes and no. the only other speaker offering those levels of performance is the Kii Three/BXT combination at over three times the price.
Keith

I definitely did not have in mind it's not worth it. It's just that for my use it would be an overkill. I'm planning to change my aging Focal Arias in near future and looking around for a nice cost effective solution. My use case is 95% home theatre and I already use 2 subs, so 3-way tower or monitors + matching centre would be perfect.

 

[torgeirs]

Just wonder about x-over heat and the low sensitivity.
The tweeter would normally be 90 dB + in a waveguide. Maybe 93. That means 10 dB damping, or allmost all power goes to passive x-over in HF.
Will not the xover overheat with a 200+ watt amp at high volume over time?

 

[stigger]

Sorry for a maybe naive question, but I don't trust myself at reading the measurements correctly yet, so: how do these sealed speakers compare against sealed KEF R3 Metas? Seems like the Metas have a somewhat flatter HF, and the rest of the differences can be eq'd out? And in return F6Bs have a smaller size and a much cheaper price, which seems like a good deal. I was looking at KEFs for a while, but now very tempted by the F6Bs. If only there was a matching center channel as well...

 

[amirm]

Just wonder about x-over heat and the low sensitivity.
The tweeter would normally be 90 dB + in a waveguide. Maybe 93. That means 10 dB damping, or allmost all power goes to passive x-over in HF.
Will not the xover overheat with a 200+ watt amp at high volume over time?

The high frequency energy in music is quite low so unless you run sweeps, it should be OK.

 

[eyke]

@AsciLab any advantages of (waiting for) your upcoming bass stands vs just getting a separate subwoofer to pair with F6Bs?

 

[Davey]

Just wonder about x-over heat and the low sensitivity.
The tweeter would normally be 90 dB + in a waveguide. Maybe 93. That means 10 dB damping, or allmost all power goes to passive x-over in HF.
Will not the xover overheat with a 200+ watt amp at high volume over time?

The tweeter padding only dissipates power in the passband for the tweeter. (The HP filter is doing the job.)
The padding resistor(s) are likely not even warm to the touch in normal operation.

We have a very inefficient speaker system here, with low SPL capability.
There is no free lunch in speaker design.

 

[staticV3]

any advantages of (waiting for) your upcoming bass stands vs just getting a separate subwoofer to pair with F6Bs?

Cardioid bass response for smoother In- room response with fewer and less severe dips and peaks

 

[JDS]

This is a review, detailed measurements, EQ and listening test of AsciLab F6Bs bookshelf/surround speaker. It was sent to me by the company and costs US $575 [now $725 with shipping included] for a pair.
View attachment 455079
This is an absolutely gorgeous design! It feels that way as well with a solid cabinet that is neither too light, nor too heavy. I didn't know if the grill over the woofer came off so left it alone. Back side shows that it is a sealed speaker:
View attachment 455080

Company uses Klippel Near-field scanner for testing which as you all know, is the same system I use. I reviewed my measurements with them and they concur with those results.

AsciLab F6Bs Speaker Measurements
As usual, we start with our anechoic frequency response measurements:

View attachment 455081
Wow, that is one smooth response! Even when a speaker has a flat on axis response, Klippel NFS manages to tease out small variations. Here, there are not other than a gentle "bump" centered around 500 Hz. There is also a slight slope down to the on-axis response. Directivity is heavily managed/controlled as you will see in later graphs.

We can predict the early window reflections:
View attachment 455082

And as a result, predicted in-room:
View attachment 455083
Is that bump an issue or not? Will have to examine with listening tests. For now, the slope is somewhat aggressive which should result in a warmer tone.

Near-field measurements show that the woofer is responsible for that small bump:
View attachment 455084
Horizontal tweeter is exceptionally well controlled, courtesy of good design and that wide waveguide:
View attachment 455085
It is a bit narrow though as is typically the case so more of a sharp focused soundstage. Directivity shows the same:
View attachment 455086
This is what we see in well designed professional monitors! Even the vertical is well mannered for a 2-way:
View attachment 455087

I was worried that F6Bs wouldn't be able to handle the full 96 dBSLP. So went up to 91 initially. Hearing no distortion, I went to my standard 96 dBSPL and it still sounded clean!

View attachment 455088

View attachment 455089

Before I forget, sensitive is low as is the case for sealed enclosures. I estimate about 2 to 3 dB lower than average so better have good amplification.

Impedance shoots sky high as we get down to DC indicating a high pass filter:
View attachment 455091
So no worries about overdriving the speaker with too much bass.

Waterfall shows the expected time domain elongation due to 500 Hz bump:
View attachment 455092

Finally, here is the step response which is pretty clean:
View attachment 455093

AsciLab F6Bs Speaker Listening Tests and EQ:
Initial impression was super positive with a warm "glow" to the music that was a bit apparent. Otherwise, the impression was that of neutrality. I almost stopped there in my analysis but thought I should dial out the bump and see what happens:
View attachment 455094
I preferred the eq as it lightened up the tonality some, bringing extra clarity. To be sure, I switched to my Revel Salon 2 speakers and they definitely had less of a bass tilt. It is a small change though and preference will likely vary especially if you have some room modes piling on as well.

Sub-bass output was essentially zero. Go up a bit though where techno bass lives and this little speaker puts out solid tones, even causing physical sensation of bass! I did not hear distortion even as I cranked up the volume. And crank I had to do with my 400 watt amplifier. Didn't have to go near max output but did push the volume up. So definitely get a mid to higher power amplifier to drive them.

Closing my eyes and listening to one speaker as I always do, the spatial halo around the speaker was not very large. This was predicted from the directivity plot. So if you are a fan of wide dispersion, then this speaker may not be quite for you. But the reverse is also true of people who want a focused soundstage.

Overall, the response was delightful. Every reference track sounded wonderful and belied the size and cost of this speaker.

Conclusions
Amazing what happens when you follow audio science and engineering to the max: you get a very reasonably priced, gorgeous speaker that is near perfect objectively. It does things that speaker many multiples of its cost can't. I don't know how AsciLab has managed to optimize so many factors all at once without having to sell the F6Bs for thousands of dollars.

Not only is this speaker excellent for surround duty -- with its screw holes in the back for wall mounting -- but it also makes an excellent monitor or desktop speaker.

It is my pleasure to recommend the AsciLab F6Bs speaker. Don't walk, run to purchase a pair!
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Something I am having trouble figuring out from the pictures: is the waveguide around the tweeter a simple conic section, or is contoured (a bit like the "wobbly wheels" on a 1960's racing Lotus)?

 

[Selkirks]

contoured

 

[Tafelberg]

Would the

TOPPING PA5 II Plus Fully Balanced Power Amp, 140W*140W Dual Channel Class D Amp​

have any problem driving these speakers in a desktop 2.2 (R and L F6B speakers, 2 subwoofers) setup?
My listening position is a little less than 1m away from the speakers, and I usually listen at less than 80 dB.
Currently, I have KEF Q150 speakers, but I am thinking of upgrading to the F6B.

@staticV3 @amirm

 

[amirm]

Just 1 meter away? If so, I think you will be fine.

 

[staticV3]

Would the

TOPPING PA5 II Plus Fully Balanced Power Amp, 140W*140W Dual Channel Class D Amp​

have any problem driving these speakers in a desktop 2.2 (R and L F6B speakers, 2 subwoofers) setup?
My listening position is a little less than 1m away from the speakers, and I usually listen at less than 80 dB.
Currently, I have KEF Q150 speakers, but I am thinking of upgrading to the F6B.

@staticV3 @amirm

The PA5II can theoretically drive the F6B to ~104dB SPL at 1m, or ~107dB SPL with the Asci's placed near a wall.

That's both at the limit of the F6B's capabilities and far in excess of your stated playback levels.

And that's the regular PA5II btw.

Spending extra on the Plus nets you just 1dB more headroom, which neither your ears nor the Asci's can likely take advantage of.

+1dB ≈ +7% perceived loudness. Barely detectable.

Edit:
Calculated values are for the F6B with passive radiator.

For the F6Bs sealed variant, simply subtract 1dB from the calculated levels

 

[Bucking]

Could the F6bs be layed on its side to be used as a center?

 

[Ricardojoa]

Could the F6bs be layed on its side to be used as a center?

Absolutely! The vertical directivity measures better than most 2 way without a wave guide.

 

[Bucking]

Absolutely! The vertical directivity measures better than most 2 way without a wave guide.

Perfect

 

[amirm]

Researching new ways to test anything, new pharmaceuticals or audio equipment, is what science is about. Most of the audio equipment tests we use today were not available decades ago. What makes anyone think that we are at the peak of testing now? I know how important it is to believe that the choices we made are perfect... but...

Generic topic don't belong in review threads. We have master threads for such complaints.

 

[Gremlins]

great review, great speakers!

if someone buys one to EU, i would be interested knowing - import duty/tax

They are on audiophonics

 

[RickS]

As Amir posted, this is a review thread and so a number of off topic posts were deleted.

Please report off topic posts as otherwise I have to delete the replies too.