AsciLab speakers are about to launch

[Curvature]

Does the C8C, as a cardioid-directional loudspeaker, need to be placed far away from walls?

A friend of mine said that when a cardioid loudspeaker is placed close to a wall or a desk, it will form directional lobes, causing abnormal directivity. According to this view, correct placement would require keeping it more than one meter away from surrounding walls. If that’s the case, cardioid loudspeakers would be almost impossible to use in bedrooms or smaller living rooms.

So does the C8C have this problem?

This is certainly false. The main problem here is called speaker boundary interference response, affecting the 100-500Hz range, although the bigger effects tend to happen below 300Hz. This affects all speakers and the issues are nonminimum phase (cancellations from reflections) and therefore difficult to EQ.

I don't want to write exhaustively on how to assess different speaker radiation patterns with boundaries. Safe to say that cardioid speakers reduce SBIR because they have controlled directivity, with less energy radiating to the sides and back, limiting the strength of reflections, making speaker placement more flexible. The effect is roughly equivalent to reflection control through treatment, although that method is very difficult and far more expensive. Some say that speakers should only ever be flush-mounted monopoles (forward-firing speakers set inside walls so that the baffle is aligned with the front wall's face).

SBIR can be calculated in advance by knowing only speaker and room dimensions. The calculated figures can then be made more precise by applying anechoic speaker measurement data like the kind Ascilab posts.

The rough "rules" for dealing with SBIR involve placing speakers less than 1m away from the front wall, or ideally more than 2m away. These rules are for people who don't want to understand the underlying phenomena and math. I generally counsel most to put their speakers right up against the front wall and not to worry about the ceiling, floor, sidewalls or speaker height. How complex the advice gets depends on how much you want to understand and what your goals are.

 

[sigbergaudio]

Does the C8C, as a cardioid-directional loudspeaker, need to be placed far away from walls?

A friend of mine said that when a cardioid loudspeaker is placed close to a wall or a desk, it will form directional lobes, causing abnormal directivity. According to this view, correct placement would require keeping it more than one meter away from surrounding walls. If that’s the case, cardioid loudspeakers would be almost impossible to use in bedrooms or smaller living rooms.

So does the C8C have this problem?

Not true. Both our cardioid speakers and for instance the Dutch&Dutch 8C works well close to the rear wall, both are actually designed for such a placement. So your friend is misinformed.

 

[napfkuchen]

A friend of mine said that when a cardioid loudspeaker is placed close to a wall or a desk, it will form directional lobes, causing abnormal directivity. According to this view, correct placement would require keeping it more than one meter away from surrounding walls. If that’s the case, cardioid loudspeakers would be almost impossible to use in bedrooms or smaller living rooms.

Erin mentioned in his review of the cardiod speaker I use that you don't need to worry about near backwall placement and I can confirm that in practice. Despite a distance of only about 10 cm to the back wall, there are no SBIR-nulls visible in measurements. In room response follows the predictions of the spinorama measurements for the most part, so I limited the room correction to the range below 325 Hz.
It's great that this technology exists. A 1m speaker-to-wall distance wouldn't be feasible in my living room.

I'm very curious to see what price the C8C/BX8C will be offered at. Competition is good and could perhaps curb the rampant price inflation among the current market leaders.

 

[Purité Audio]

Pricing for the C8C/BX8C have been finalised, in the ‘pre-order’ period which runs up to the 31st December 2025,
C8C per pair in either of the two standard colours are $4995 ex-vat rising to $5400 per pair in the New Year.
BX8C per pair ex-vat $5445 rising to $5995 after the pre-order period ends.
Keith

 

[goat76]

Not true. Both our cardioid speakers and for instance the Dutch&Dutch 8C works well close to the rear wall, both are actually designed for such a placement. So your friend is misinformed.

When you say they are designed for a placement close to the back wall, do you mean they don't work as well if the placement is 1 meter or further away from the back wall?

I’m asking this because I actually want my speakers at least one meter out from the wall to get them fairly close to the listening position in my room, as that will give me a higher ratio of direct sound. And besides that, it is also important, if not the most important thing, to find the best possible listening spot in the room with the least acoustic compromises. There isn't much room for all these other sound optimisation parameters if the speakers have to be placed close to the back wall to perform their best.

 

[kharan]

What about side walls?

 

[slowTwitch]

Knock them down.

 

[pat355]

Knock them down.

would repainting them do the trick too?

 

[slowTwitch]

Yes, but only after they've been knocked down. Can't beat a bit of painted rubble imo. It acts as a diffuser.

 

[pat355]

Yes, but only after they've been knocked down. Can't beat a bit of painted rubble imo. It acts as a diffuser.

I read cardioid excels in such a configuration - better soundstage, sound is more refined, better separation of instruments, blablabla - the whole audiophile bingo card.

 

[sigbergaudio]

When you say they are designed for a placement close to the back wall, do you mean they don't work as well if the placement is 1 meter or further away from the back wall?

Slightly off topic in the Ascilab thread I guess, but at least for the Sigberg cardioids and I suspect also for the D&D, the cardioid effect won't care if you place them further out. But it will affect the bass performance of both the 8C/6C and also our Saranna. But they all have options to adjust the bass level, so that's fine too.

I’m asking this because I actually want my speakers at least one meter out from the wall to get them fairly close to the listening position in my room, as that will give me a higher ratio of direct sound.

Yes, that's a bit of a compromise with speaker placement. Closer to the wall will give you less SBIR effects, but if you're unable to move your listening position as well, it might give you less direct sound / not as wide of a soundstage. But then again, more direct sound is one of the benefits of cardioid, so you'll get as close to best of both worlds as possible even if you place them closer to the wall.

And besides that, it is also important, if not the most important thing, to find the best possible listening spot in the room with the least acoustic compromises. There isn't much room for all these other sound optimisation parameters if the speakers have to be placed close to the back wall to perform their best.

Not sure if I understood that final sentence. A cardioid speaker can be experimented with just as much as any other speaker. But actually close to the wall is usually an optimal placement on many parameters even for a traditional speaker. That being said, if you put a cardioid speaker further from the wall, it won't perform worse than a traditional speaker on any parameters.

The biggest difference between a speaker designed for placement close to the wall vs far from the wall will typically be how it is tuned in the bass.

 

[AsciLab]

The rule of thumb that closer speaker placement to the rear wall is about avoiding strong rear wall SBIR cancellation.
Unfortunately SBIR is occurred from all surface. Usually floor and ceiling bounce is overlooked which gives quite strong effect to the high bass to low midrange.

But let’s say about rear wall SBIR.

Considering to our cardioid pattern, you can easily calculate proper distance from the rear wall to the baffle. For example, our C8C and BX8C combo keeps its directivity down to 50Hz at -6dB line. If you place the speaker 1.7m away from the rear wall, then you can get roughly -6dB dip around 50Hz by the rear wall SBIR.
Usually Omni-direction bass gets much more strong dip if you place like that. And If you place more near to the rear wall saying 1m, cause BX8C combo has more than -10dB attenuation at the 85dB to the 180deg, you can less than 3dB dip around 85Hz. That amount of dip can be easily corrected by EQ.

Of course this example is just ideal and limited calculation. Real room SBIR is much more complex.

Furthermore, Cardioid is not only for less SBIR. Usually most speaker has directivity above 1kHz. But the extended directivity down to 100Hz can make the ASW much more consistent and then you hear same sound imaging and localization over the whole range. Bass is there right at the mid and high bands are. Much deeper and exact sound stage will hear. It’s more like seeing the sound than hearing as my experience.

 

[kharan]

My earlier "what about side walls" wasn't clear enough.

My thought is that we need the sound wave from the side woofer to interact with the sound wave from the front medium to properly cancel and form a cardioid pattern, if the wall is closer to the side drivers than to the front drivers, I don't know what would happen. Pushed to the extreme, you wouldn't place the C8C in a book self surrounded by books.

So the question is how far way from a side wall does the C8C need to be at minimum?

 

[jeo12]

Very impressed with the C8C measurements, but personally more interested in the smaller model. Any news on that? Timeline?

 

[AsciLab]

My earlier "what about side walls" wasn't clear enough.

My thought is that we need the sound wave from the side woofer to interact with the sound wave from the front medium to properly cancel and form a cardioid pattern, if the wall is closer to the side drivers than to the front drivers, I don't know what would happen. Pushed to the extreme, you wouldn't place the C8C in a book self surrounded by books.

So the question is how far way from a side wall does the C8C need to be at minimum?

Will you place the speaker less than 15cm from the side wall?

 

[Purité Audio]

Originally The C8C was called the C6C, so it is the ‘smaller’ one, the S6C is all Purifi with its dedicated BX10C sub module.

https://www.puriteaudio.co.uk/_files/ugd/5cac3a_dd3effcb0da34b038138cf5597f37d25.pdf

Keith

 

[jeo12]

Thanks Keith, I should have been clearer: I was thinking about what used to be called the C5C (now probably C7C?).

 

[Matt_Holland]

The best VFM for me looks like being the C8T which, based on prototype measurements, has cardioid like dispersion down to ~200Hz and will be significantly less money than the C8C.

 

[polyphony]

I was lucky to get a pair of the C6B from the latest batch through testedaudio. The shipping was fast and having listened for a couple days I am extremely impressed which also makes me interested in the C8C & BX8C combo... are there any plans to offer that pre-order price through testedaudio?

 

[kharan]

Will you place the speaker less than 15cm from the side wall?

There is some shelving on both side of the room that reduce the available width which isn't great to start with (3.2 m), so it would be good to know if I also need to move the shelving or of it can be placed close to it.