Why is the Active Cardioid unpopular in DIY projects?

[P.L.]

I have worked on several DIY cardioid projects and plan to post about one of them.
While reviewing existing DIY cardioid projects for that, I found that most DIY projects focus on passive designs.
(I mean, not sub-base only but fullrange, including midrange)

The only active cardioid project I found is this one:
http://www.hifi-forum.de/viewthread-104-28780.html

I would like to determine whether this conclusion is due to the limitations of my search abilities, or if there is a specific reason why people do not prefer the active approach.
If you could provide information on other projects, I would greatly appreciate it.

 

[voodooless]

I think the DIY audio community in general is still stuck in passive mode. The same goes for the non-DIY audio communities. Too much random tinkering, too little applied science and engineering. DACs, Amps and crossover components are seen as tinkering devices, instead of items with known properties.

 

[P.L.]

I think the DIY audio community in general is still stuck in passive mode. The same goes for the non-DIY audio communities. Too much random tinkering, too little applied science and engineering. DACs, Amps and crossover components are seen as tinkering devices, instead of items with known properties.

I appreciate your response, but my intention here is to discuss active (such as the Kii 3) and passive (such as the Dutch 8c) implementations in the context of the cardioid design, which is quite different from the general concept of active and passive amplified speakers.

 

[voodooless]

I appreciate your response, but my intention here is to discuss active (such as the Kii 3) and passive (such as the Dutch 8c) implementations in the context of the cardioid design, which is quite different from the general concept of active and passive amplified speakers.

That’s not what you asked initially, though

As for active vs passive, it should be quite clear that active with DSP is vastly superior: you can endlessly test out filter changes for free, you can do non-causal filters (FIR), no issues with gain, easier to compensate for driver frequency responses, higher slopes, time delays, etc.

 

[kemmler3D]

I've seen plenty of active designs at DIYAudio but not too many cardioid, although I haven't looked lately. I think just in general cardioid is a more complex design so fewer DIY folks attempt it.

 

[P.L.]

That’s not what you asked initially, though

Well, that wasn't my intention—so I just wanted to clarify in case there was any ambiguity.

I've seen plenty of active designs at DIYAudio but not too many cardioid, although I haven't looked lately. I think just in general cardioid is a more complex design so fewer DIY folks attempt it.

Thanks for your response.
I was able to find quite a few implementations using the passive approach, but I could only find one for the active approach.
So, I wanted to check with people here to see if I might have missed anything.

 

[OldHvyMec]

If I may ask, what plate or plates are you using for your projects? Is there one in particular you like to use over another?

Regards

 

[mcdn]

The D&D 8c is hardly a passive design either, and it took many years to develop, a lot of it with the support of the DIYAudio community. I’m not sure I could name a single passive cardioid that works well, commercial or otherwise.

 

[sigbergaudio]

I think the OP is trying to discuss active cardioid (as in done with additional drivers) vs passive cardioid (as in done with acoustical vents / physical adjustments to the cabinet).

So not if it is powered / has digital crossovers / DSP or not.

 

[P.L.]

If I may ask, what plate or plates are you using for your projects? Is there one in particular you like to use over another?

Regards

If "plate" refers to a plate amplifier, I have used SpeakON to place the amplifier and DSP outside the speaker enclosure. For my next project, I am considering using a FusionAmp from Hypex.

The D&D 8c is hardly a passive design either, and it took many years to develop, a lot of it with the support of the DIYAudio community. I’m not sure I could name a single passive cardioid that works well, commercial or otherwise.

As I clarified earlier, "passive" hereby refers to a cardioid implementation method utilizing resistive ports, not the amplification method.

I think the OP is trying to discuss active cardioid (as in done with additional drivers) vs passive cardioid (as in done with acoustical vents / physical adjustments to the cabinet).

So not if it is powered / has digital crossovers / DSP or not.

Thanks!

 

[mcdn]

The midrange of the Linkwitz LXMini is a passive cardioid of sorts, but it still needs DSP

 

[sigbergaudio]

The midrange of the Linkwitz LXMini is a passive cardioid of sorts, but it still needs DSP

The discussion is not about DSP or no DSP.

 

[voodooless]

I think the OP is trying to discuss active cardioid (as in done with additional drivers) vs passive cardioid (as in done with acoustical vents / physical adjustments to the cabinet).

My guess: the main reasons are that it's a simpler setup, with fewer components, but it's also less flexible, so contained in design freedom, and arguably harder to implement.

 

[tmuikku]

Active cardioid gives more control on the pattern, but it requires enclosure per driver and more amp and processing channels making it complicated as a trade-off. Passive cardioid is also complicated in sense that tuning of the pattern isn't exactly easy as programming a DSP, but tinkering with materials and physical objects in general.

Great benefit for passive cardioid is that once good structure has found it costs almost nothing to make, because the enclosure is simpler and smaller than for a closed box for example. Benefit here is that sound that would normally go inside box and do nothing (except prevent destructive interference on bass) is now utilized to cancel sound that would normally go toward wall behind speaker, trade off is throwing away bass performance but if this is not a bass driver good riddance, bass exchanged to less sound toward back hemisphere.

So, if one is able to cover need for cardioid pattern with passive version it's much simpler than active equivalent. Active has more control though. Active system could provide variable pattern, one could turn nulls with toe-in for example, to target some particular angles to further help with specular reflections, the SBIR stuff. Active cardioid done by stacking identical boxes in various physical configurations and changing processing provides great flexibility for single set of boxes, and so on.

So, pick your poison

 

[nc535]

I've got a design in the works that has active cardioid bass and passive cardioid midrange so I've examined the tradeoffs in detail. If I were doing this for a commercial product, I would never end up with the same design, unless it were a cost no object product.

My design has an 8" coax up top, an 8" woofer below it, and dual opposed 8" side subwoofers and sits on a stand. There is a floorstander version with 4 side subwoofers.. With a complex DSP XO, I make the side woofers support the front woofer below 80 Hz and oppose it above, to create both sub-bass and cardioid directivity up to 230 Hz, where it meets the passive cardioid coax mid. To implement the XO, I need an Motu Ultralite and Camilla DSP on an Rpi4. Because of the DSP tunability, I achieve really deep attenuation to the rear. All this extra just to extend the cardioid range down another octave, but that octave is where most of the SBIR takes place. In defense of my apparent love of complexity, I would say that this design, thus far only simulated in ABEC+Vituix, has exceptionally constant directivity and is a very good choice for use close to the front wall and near corners in an untreated, smallish room.

You don't have to look very far to see how much simpler it is with cardioid just down to 175 Hz or so where an 8" passive cardioid might begin to show rising THD. Given how much cost matters to the consumer and margin matters to the producer, I can't see this being done commercially. It certainly can't compete with D&D 8C. It might be viable against Kii3+BXT, especially with a subwoofer in room for spatial diversity. For me, it's about the engineering challenge. I'm not even sure I want to take it beyond simulation. But it is a cute trick to get the side woofers to both act as sub-woofers and create directivity at the same time, which helps justify the extra cost and complexity.

 

[Trdat]

I have worked on several DIY cardioid projects and plan to post about one of them.
While reviewing existing DIY cardioid projects for that, I found that most DIY projects focus on passive designs.
(I mean, not sub-base only but fullrange, including midrange)

I am a fan of DIY and a big fan of active. Current system is a horn with 15inch and it would be great to see a cardioid design in active either with a horn or a coxial.

I would like to determine whether this conclusion is due to the limitations of my search abilities, or if there is a specific reason why people do not prefer the active approach.
If you could provide information on other projects, I would greatly appreciate it.

My opinion is that, it takes time for new technology to settle in, people need convincing, implementation needs to simplify , prices need to come down. My 2 cents worth from an amateur's perspective is that passive approach is outdated and has been surpassed.

 

[smowry]

I am presently working on the development of DIY Active Cardioid Monitors. I posted a report at LinkedIn. Here's the link.

MY RETIREMENT PROJECT (Part 1)

1. OBJECTIVE: A DIY Active Cardioid Monitor Loudspeaker Project 2.

www.linkedin.com

 

[gene_stl]

The Airfoil – VPE Electrodynamics

vpeelectrodynamics.com

 

[Pareto Pragmatic]

I assume a big reason you are not seeing a lot is that many people have never heard of the term "cardioid". Crutchfield, for example, lots of cardioid mics, but not much for speakers/subs.

Second, DIY tends to follow a path from "the simple easy project" to "very complicated project", and along the way many people drop out. They do one, a second, and that's enough. Simple = passive in most people's minds, less to learn, less to worry about. If I make a passive speaker, then the next one is simple. Adding active aspects means a whole different approach and more to learn before design and construction.

So I see lots of reasons for low demand for such plans/projects, and those who make such things generally want to at least sell the plans if not the parts and won't spend much time marketing to a very small market segment. They will focus on "bigger selling potential" options first, and maybe eventually go cardioid plans/parts.

So I would say DIY active cardioid puts a person WAY out on the tail of the curve. Even here, this thread on ASR, 20 posts, 4 years old. https://www.audiosciencereview.com/forum/index.php?threads/diy-cardioid-designs.11663/ It seems a niche of a niche area to me.

 

[smowry]

Active Cardioid interest seems to be just that, a subjective interest.

Martin J King said the following to me back in April. "I really have no experience in Cardioid or Unidirectional speaker design, it is not something I am interested in right now. I have two or three projects/theory exercises of my own that I am currently working and I move at my own slow pace so they are long term goals." Now here's a guy that named his website quarter-wave.com.

Then when I visited Genelec in Finland, Ilpo told me that "Directivity is everything".

When I met and interviewed Neville Thiel in Malaysia, he poked fun at Acoustic Resistive enclosures.

Then when I recently tried to discuss my Flower Concept with General* Danny Richie, he referred to it as a disaster. "Between the Dayton Audio drivers and MiniDSP, it looks like a recipe for a disaster." He then went on to say, "The only Genelec speakers I have ever heard, sound like crap." "The Kef design is a gimmick and just something for their marketing department to run with. If they were really interesting in performance then they would use garbage level crossover parts in their speakers." Coaxial arrays are a "gimmick"?

My point is that few industry leaders embrace Active Cardioid Systems, thus the DIY community follows that model. In my case working with Ilpo for 3.5 years had an impact on my interest. Specifically, without the Genelec experience, I would most likely feel like Martin about Active Cardioid, something I would not be interested in!

As most understand, respect is best earned. Having said all this, it appears that the Active Cardioid Loudspeaker Concept has yet to earn the industry's respect. Regardless of that, I went with Ilpo.


*Note that in Audio, the designation of General refers to one who generalizes.