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A few questions about cardioid subs

ReDFoX

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Joined
May 23, 2022
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Location
Russia, Samara
Hi ASR, it's been almost 2 years since I first heard about cardioid speaker design being implemented in mass-production (it was during D&D ad campaign I guess). Last year I had a chance of listening to 8c and KH310 (w. 750 sub) side by side along with some Amphions, and while I disliked the"out of the box" V-shaped FR of 8cs, there was something in the upper-bass region that separated them from the rest. A feeling of that uncanny headphone-like ability of 8c to produce such clean bass earned a place in my speakers "watchlist", although I was blown away by 310s, especially the soundstage they created. Sooo, earlier this year, out of the blue, Genelec announces their 8381 which also has cardioid LF design.

After their release I did a quick search only to realise that there aren't many articles or studies on this subject, moreover, the number of commercially available is extremely low and the only thing I can possibly afford is Beag HEC 45 (they're ~500$ if I convert a price at the official rate).

The next biggest thing is room. I have ~2.2x5.5x2.7 room which really helps with LF modes but the upper-bass region is still a total mess despite quite a few absorbers with high-density rockwool placed on walls.

So, having almost the whole summer ahead, my questions will be:
1. Is it possible for a sub to operate in cardioid mode in such a small room?
2. Is there a software or some kind of script for precise modelling of waves behaviour?
ones that I've seen on the internet do not allow precise calculations
3. Is there a possibility to build a cardioid (based on delay between drivers) sub w/o "real" measurements (outdoor/anechoic)?
I live in a city centre and have no opportunities of making frequent outdoor measurements (although I can do them in theory)

I would appreciate any articles about real world examples of active cardioid designs, especially, from a calculation perspective. Since my english is far from perfect and I'm new to this subject I'd be happy to hear any answers or suggestions from people, who already had experience with such designs.


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bigjacko

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Sep 18, 2019
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Cardioid sub are not that useful because room mode dominate at those frequencies. Cardioid will have higher distortionat low frequency, more monopole sub is better. The only benefit of cardioid might be when you place the sub at a distance to the wall, cardioid can avoid SBIR.

Cardioid need some space to work as the cancelation happens after a certain distance. Not sure how long but can be a few meters. So put it against the wall and sit 1m in front of it, it will not be cardioid.

Do you want to simulate cardioid? VituixCad can do it, and it is easier. Akabak is another one but has very steep learning curve.

Normally subbass frequency are close to simulation, so probably you will be fine without measurement. But being able to measure can verify what you have done.

This thread from crtl is a good read.

There are many threads on diyaudio too. I don't have very good theory article....
 
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