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 for a
pair.
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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:
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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:
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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:
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And as a result, predicted in-room:
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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:
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Horizontal tweeter is exceptionally well controlled, courtesy of good design and that wide waveguide:
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It is a bit narrow though as is typically the case so more of a sharp focused soundstage. Directivity shows the same:
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This is what we see in well designed professional monitors! Even the vertical is well mannered for a 2-way:
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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!
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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:
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So no worries about overdriving the speaker with too much bass.
Waterfall shows the expected time domain elongation due to 500 Hz bump:
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Finally, here is the step response which is pretty clean:
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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:
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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!
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