Ascilab C8C Active Speaker Review

[AudioJester]

I have had loads of non-cardioid setups. My listening space is accoustically terrible.
The C8C measures and sounds the best so far - can only assume due to the cardioid effect.

 

[staticV3]

I know I'm over simplifying and not trying to wind people up....but if the speaker falls short in measurements in one area surely the manufacturer can just tune it out with the DSP? Subject to distortion physical parameters.
In other words you can polish the performance. Improve the graphs?

Frequency response and phase response are the only parameters which a manufacturer can realistically tune out after the fact.

Everything else (directivity, distortion, compression, group delay, burst decay) is usually subject to physical speaker properties and cannot be tuned with DSP.

Edit:
There are exceptions of course, like DSP driven directivity and limiters, but even then the possibilities are limited.

Like with the C8C for example, Ascilab could totally update their C8C firmware to include the notch filter which Amir applied to his unit, if they found that to be a consistent improvement across all units, but the directivity lobing that the C8C shows in the midrange cannot just be tuned out with an updated DSP config.

 

[jEDGEc0m]

I have had loads of non-cardioid setups. My listening space is accoustically terrible.
The C8C measures and sounds the best so far - can only assume due to the cardioid effect.

I imagine the excellent directivity of the AsciLab could certainly be a factor, depending on the competition you're comparing against.

I see your recent measurements of the C8C

Ascilab C8C Active Speaker Review

From their own measurements, in 96 dB, HD relative, from best to worst between these 4. IMO the A6B is the overachiever. C8C + BX8C crosses -50 dB around 80 Hz. A6B crosses -50 dB around 100 Hz. C8C crosses -50 dB around 150 Hz C8T crosses -50 dB around 180 Hz. The real winner here is...

www.audiosciencereview.com

Do you have some measurements you could share of other speakers in the same space/location for comparison?

 

[AudioJester]

Do you have some measurements you could share of other speakers in the same space/location for comparison?

I was hoping you would not ask that as i have never done it in a systematic comparative way, measurement was more so just a tool to get the best out of what I had set up.

This is C8C and Genelec 8361a. Both on same stands in same position. Different toe in/out. 8361a was measured at 1.2m listening distance, found it got much more room interaction at longer listening distances. C8C is measured at 2.5m listening distance. 8361a measured with GLM, C8C with Acourate.

 

[Arthur Edwards]

So, you can create a cardioid radiation pattern in two different ways:

1. Use the back wave from the driver to cancel out the side radiation via carefully tuned ports - this is the D&D, Amphion, Palmer etc way of doing things. Upsides, this system is entirely passive so can be done in analog active or even completely passive speakers and doesn't require any additional drivers or amp and DSP channels. Downside is you need a driver with considerable excursion capability to keep good linearity at more elevated levels if you want the directional behavior to really reach down to the region it's most useful in.

2. Use extra drivers and DSP delay lines - this is the Kii, Mesanovic, Ascilab etc way of doing things. Upside, you don't lose headroom from adding the cardioid response and it can be tuned very precisely. Downside is this is a considerably more expensive option in terms of both complexity and in terms of raw BOM cost (more amp and DSP channels, more drivers).

I am experiencing some confusion.

I am referring to the attenuation of lateral acoustic radiation at midrange and high frequencies, not at low frequencies. The slots are designed to achieve this attenuation. The midrange sound emerges 180 degrees out of phase, which is paired with a substantial waveguide for the high-frequency driver.

The Kii addresses bass issues using side and rear drivers with DSP. Dutch & Dutch employs a rear-firing bass driver and DSP; I believed the slots and rear woofer DSP functioned independently to achieve a full-range cardioid characteristic. Is the Ascilab C8C only implementing a cardioid in the bass frequency range? Amphion uses slots and is passive, so its bass response is not cardioid.

 

[jEDGEc0m]

I was hoping you would not ask that as i have never done it in a systematic comparative way, measurement was more so just a tool to get the best out of what I had set up.

This is C8C and Genelec 8361a. Both on same stands in same position. Different toe in/out. 8361a was measured at 1.2m listening distance, found it got much more room interaction at longer listening distances. C8C is measured at 2.5m listening distance. 8361a measured with GLM, C8C with Acourate.

View attachment 516797View attachment 516798View attachment 516799

Still definitely interesting even if not directly comparable. Thanks.

If just looking at graphs instead of listening to sound, there are certainly some similarities to be seen - notably the peak at about 50hz, and the broad dip ~50-100hz. And obviously the impressive extra low extension from the C8C - up against the bog-boy 8361A, that's saying something. Even at different measurement distances of the different speaker systems, some of the room’s influence seems to remain consistently evident in the low end. Interesting.

Other than the extra extension, with eq applied, I imagine the "lines" could look similar. but you've already said things sound favourable with the AsciLab - so that's great to hear, considering we're talking about comparison with something as awesome as the Genelec 8361A.

Thanks for providing! yeah, based on graphs, I'd maybe think cardioid might not be particularly "game changing". But I'd certainly like to experience it for myself some day.

 

[Purité Audio]

I find a very worthwhile benefit to cardioid response and why I have pursued cardioid designs, early on it was comparing the non-cardioid D&D 8M to their otherwise similar cardioid 8C,
Keith

 

[AudioJester]

Still definitely interesting even if not directly comparable. Thanks.

If just looking at graphs instead of listening to sound, there are certainly some similarities to be seen - notably the peak at about 50hz, and the broad dip ~50-100hz. And obviously the impressive extra low extension from the C8C - up against the bog-boy 8361A, that's saying something. Even at different measurement distances of the different speaker systems, some of the room’s influence seems to remain consistently evident in the low end. Interesting.

Other than the extra extension, with eq applied, I imagine the "lines" could look similar. but you've already said things sound favourable with the AsciLab - so that's great to hear, considering we're talking about comparison with something as awesome as the Genelec 8361A.

Thanks for providing! yeah, based on graphs, I'd maybe think cardioid might not be particularly "game changing". But I'd certainly like to experience it for myself some day.

Thats the best position and listening distance I got with the 8361a. Did not save others, but measurement was much worse at 2.5m. I really needed to be more nearfield in my listening space with the 8361a - this area has floating wood floor, sloping ceiling and glass on 3 sides! I have other spaces, but here I can listen loud and late without disturbing others.

The C8C is a starting point. Need to work on them a bit more, need to raise the stands a bit. I feel the improvement between 100-300Hz and the mids and top end is "cleaner" and more spacious, but that may be listening distance.

To answer your question, cardioid allows me to get pretty good sound at longer listening distances without completely sucumbing to room effects. I could not achieve this with non-cardioid in my listening space.

 

[Marin]

These are Class-D. They will not get hot.

Oh, it's going to get really hot..
It all depends on the level of amplification and the cooling that is installed.

 

[kharan]

I am experiencing some confusion.

I am referring to the attenuation of lateral acoustic radiation at midrange and high frequencies, not at low frequencies. The slots are designed to achieve this attenuation. The midrange sound emerges 180 degrees out of phase, which is paired with a substantial waveguide for the high-frequency driver.

The Kii addresses bass issues using side and rear drivers with DSP. Dutch & Dutch employs a rear-firing bass driver and DSP; I believed the slots and rear woofer DSP functioned independently to achieve a full-range cardioid characteristic. Is the Ascilab C8C only implementing a cardioid in the bass frequency range? Amphion uses slots and is passive, so its bass response is not cardioid.

There is no attenuation needed for the high frequencies, the tweeter and its waveguide already do that. For the mids, above about 800 Hz, the size of the midwoofers already makes their output beam. Between 100 Hz and 800 Hz, the side woofers are also playing signal delayed in order to cancel the side and rear output of the midwoofers, even though as we near 800 Hz, that output is very diminished.

You can see this in Amir's near field measurements.

Hmm, I have no idea why there's a bump in the sub left response around 600-800 Hz, I don't think there's a resonance there.

 

[totti1965]

Here is my take on the EQ.

Please report your findings, positive or negative!
For the score rational your journey starts here
Explanation for the sub score
The following EQs are “anechoic” EQs to get the speaker right before room integration.
If you able to implement these EQs you must add EQ at LF for room integration, that is usually not optional… see hints there.

The raw data with corrected ER and PIR:

Score no EQ: 7.3
With Sub: 8.1

Spinorama with no EQ:

• SOTA
• Waveguide ON/LW discrepancy?

View attachment 516290
Directivity:
Better stay at tweeter height
Horizontally, better toe-in the speakers by 10/15deg and have the axis crossing in front of the listening location, might help dosing the upper range. explanation here
View attachment 516306

EQ design:
I have generated two EQs. The APO config files are attached.

• The first one, labelled, LW is targeted at making the LW flat
• The second, labelled Score, starts with the first one and adds the score as an optimization variable (here).
• The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment although the LW might be better suited for this purpose.
• One can model the EQ with Vituixcad by using the DSP "Generic" setting with 96000Hz sampling rate.

Score EQ LW: 7.1
with sub: 7.8

Score EQ Score: 7.7
with sub: 8.5

AsciLab C8C APO LW EQ 96000Hz
March092026-103546

Preamp: -1.90 dB

Filter 1: ON HPQ Fc 22.3 Hz Gain 0.00 dB Q 1.14
Filter 2: ON PK Fc 2120.3 Hz Gain 0.57 dB Q 1.35
Filter 3: ON PK Fc 4644.5 Hz Gain -0.94 dB Q 2.58
Filter 4: ON PK Fc 14522.3 Hz Gain 1.26 dB Q 0.46

AsciLab C8C APO Score EQ 96000Hz
March092026-103546

Preamp: -2.00 dB

Filter 1: ON HPQ Fc 22.3 Hz Gain 0.00 dB Q 1.15
Filter 2: ON PK Fc 1083.6 Hz Gain 0.55 dB Q 6.00
Filter 3: ON PK Fc 4810.3 Hz Gain -1.25 dB Q 2.29
Filter 4: ON PK Fc 11025.5 Hz Gain 0.59 dB Q 6.00

View attachment 516296
Spinorama EQ LW
View attachment 516291

Spinorama EQ Score
View attachment 516292

Zoom PIR-LW-ON
View attachment 516295

Regression - Tonal
View attachment 516294

Radar no EQ vs EQ score
Does Not EQ
No improvements?
View attachment 516293
The rest of the plots is attached.

@pierre: can you please add some of the insights of @Maiky76 to the spinorama.org side?
Would be nice to see the AsciLab C8C also for the Ranking "Preference Score WITH Eq"
Must be something like 7.6 or 7.7?

The Problem is: If you look at "Measuring Quality high" + "Preference Score WITH Eq" the speaker doesn´t show up at all!
Even not with its 7.24 Score without equalization!

It would be nice, if you could fix this perhaps per programming the spinorama site: Even with no EQ at all the C8C must be ranked somewhere between March Audio Sointura WITH EQ and Neumann KH 150 WITH EQ, if a spinorama user clicks
"Measuring Quality high" + "Preference Score WITH Eq"

The same problem would occcur for any other speaker which has no valid indication for "Preference Score with EQ"!
Instead of just dissapearing, it would be better to let pop up at least the worse score for just ranking by "SCORE"

All of this could be a problem for Spinorama users with not so much "Insider knowledge" like some of us.

Thank you for your incredibly work for the spinorama.org site and the github spinorama discussion group!!!

 

[totti1965]

Here is my take on the EQ.

Please report your findings, positive or negative!
For the score rational your journey starts here
Explanation for the sub score
The following EQs are “anechoic” EQs to get the speaker right before room integration.
If you able to implement these EQs you must add EQ at LF for room integration, that is usually not optional… see hints there.

The raw data with corrected ER and PIR:

Score no EQ: 7.3
With Sub: 8.1

Spinorama with no EQ:

• SOTA
• Waveguide ON/LW discrepancy?

View attachment 516290
Directivity:
Better stay at tweeter height
Horizontally, better toe-in the speakers by 10/15deg and have the axis crossing in front of the listening location, might help dosing the upper range. explanation here
View attachment 516306

EQ design:
I have generated two EQs. The APO config files are attached.

• The first one, labelled, LW is targeted at making the LW flat
• The second, labelled Score, starts with the first one and adds the score as an optimization variable (here).
• The EQs are designed in the context of regular stereo use i.e. domestic environment, no warranty is provided for a near field use in a studio environment although the LW might be better suited for this purpose.
• One can model the EQ with Vituixcad by using the DSP "Generic" setting with 96000Hz sampling rate.

Score EQ LW: 7.1
with sub: 7.8

Score EQ Score: 7.7
with sub: 8.5

AsciLab C8C APO LW EQ 96000Hz
March092026-103546

Preamp: -1.90 dB

Filter 1: ON HPQ Fc 22.3 Hz Gain 0.00 dB Q 1.14
Filter 2: ON PK Fc 2120.3 Hz Gain 0.57 dB Q 1.35
Filter 3: ON PK Fc 4644.5 Hz Gain -0.94 dB Q 2.58
Filter 4: ON PK Fc 14522.3 Hz Gain 1.26 dB Q 0.46

AsciLab C8C APO Score EQ 96000Hz
March092026-103546

Preamp: -2.00 dB

Filter 1: ON HPQ Fc 22.3 Hz Gain 0.00 dB Q 1.15
Filter 2: ON PK Fc 1083.6 Hz Gain 0.55 dB Q 6.00
Filter 3: ON PK Fc 4810.3 Hz Gain -1.25 dB Q 2.29
Filter 4: ON PK Fc 11025.5 Hz Gain 0.59 dB Q 6.00

View attachment 516296
Spinorama EQ LW
View attachment 516291

Spinorama EQ Score
View attachment 516292

Zoom PIR-LW-ON
View attachment 516295

Regression - Tonal
View attachment 516294

Radar no EQ vs EQ score
Does Not EQ
No improvements?
View attachment 516293
The rest of the plots is attached.

Score EQ LW: 7.1
with sub: 7.8


EQ is Equalisation - but can you tell me what LW is?

Thanx for your great work!!!

 

[markstein]

Score EQ LW: 7.1
with sub: 7.8


EQ is Equalisation - but can you tell me what LW is?

Thanx for your great work!!!

LW = Listening Window

 

[pierre]

Score EQ LW: 7.1
with sub: 7.8


EQ is Equalisation - but can you tell me what LW is?

Thanx for your great work!!!

Not Maiky but

LW == Listening Window

My take on it: optimising for flat LW is good for near field listening. Far field aka living room, optimising for a flat ER or PIR is better. That's what the score does (optimising the PIR==Predicted In-Room Response).

 

[DearSX]

With EQ = 7.85 Wow!

Measurements for speaker AsciLab C8C

www.spinorama.org

 

[Marin]

Default (measured) on-axis and power average slopes are not very compatible with directivity spectrum. Frequency range with close to constant directivity index should have negative on-axis slope to get suitable slope for PIR and SP. Suitable slope targets for conventional multi-ways are mentioned in 'Multiple Regression Model for Predicting Loudspeaker Preference...' by S. Olive. PIR slope of -1.0 i.e. -0.69 dB/oct. is good 'factory default' target also for concepts closing to constant directivity. Ideal CD has the same slope for on-axis and power averages such as PIR and SP. Slope of 0 dB/oct. would produce too thin sound as CD with low overall directivity such as DI=5...10 dB. Stronger overall directivity with much larger LF radiators are able to challenge this rule of thumb, but probably doesn't enable 0 dB/oct. Has not enabled in practice so far ime.

This EQ produces more suitable slopes with C8C. General tilt of ca. -0.37 dB/oct. and reducing LF power due to omni bass should help overall balance to far field. Near field is different case.
View attachment 516224
Result as spinorama.

View attachment 516216

Another problem is that directivity changes from omni (DI=0) to cardioid (DI=4.8) from 68 Hz to 200 Hz. That is kinda unavoidable with tiny cardioid speakers, but it happens too rapid and too high. Cardioid covering also mid and upper bass (40...160 Hz) is helpful in practice (without multi-sub or flush-mounted half space system).

Yes, I'm interested in this too.
The slopes of A6b and F6b seems to be close, but I would characterize C8c as too thin or bright sound

compared to the first two.

 

[Matt_Holland]

Yes, I'm interested in this too.
The slopes of A6b and F6b seems to be close, but I would characterize C8c as too thin or bright sound View attachment 516845compared to the first two.

C8T very similar to C8C. Interestingly no-one is saying the C8C sounds bright with the exception of Amir's comment on the 4KHz peak (which is subtly in the PIR). Comments seem to be mostly related to the incredible resolution and separation. I think C8C/C8T PIR is preferable when horizontal dispersion is in the 40-50deg range.

 

[Marin]

So basically, the amps offer a 120F space heater inside the cabinet while playing? Does it cool off in idle mode or do you have to unplug the speaker to drop the heat? Does the speaker have open ports that allow cooler air to enter? Thank you!

Design with ports whoud definitely help that cooler air enter and cooles amplifier behind the plate.
Unfortunately I don't see any openings other this little holes on plate.
Is this enough to keep this amplifier cool and in working order for years to come?

 

[pat355]

View attachment 516847

C8T very similar to C8C. Interestingly no-one is saying the C8C sounds bright with the exception of Amir's comment on the 4KHz peak (which is subtly in the PIR). Comments seem to be mostly related to the incredible resolution and separation. I think C8C/C8T PIR is preferable when horizontal dispersion is in the 40-50deg range.

it doesn't sound "bright" to me at all. Subjective, yes - but I played guitar in a band for 2 decades and any brightness in my Strat always bothered me so I'm sensitive to this. I can't say I've noticed anything in that respect at least until now...

 

[Marin]

So basically, the amps offer a 120F space heater inside the cabinet while playing

Yes, that worries me a lot, and that's why I'm skeptical of active speakers.
There is so much talk about how much voice coil and engine heat in general contributes to compression in passive speakers...