Big 2-way - cardoid

[TimVG]

Just realized I never posted an action shot..

 

[abdo123]

Just realized I never posted an action shot..

These pannels at the back almost make no sense now with the cardioid directivity . This is great stuff, do you think you will fine tune the design in the future?

 

[TimVG]

Nicer cabinets are on my to-do list, as are ground plane measurements but from the looks of it we're looking at 2022 for those. Fine tuning a passive cardioid system will require lots of trial & error and would unfortunately mean lots and lots of labor. Unless you're looking at making a whole bunch it's probably not worth the hassle. Active cardioid is also something I'd be interested in trying and would only require an extra amp and DSP channel, I actually have a couple of 10" eminence bass cabinet drivers around which would probably work well as a rear driver to achieve a cardioid pattern.

And yeah, those panels are probably not doing all that much anymore now.

 

[dc655321]

Fine tuning a passive cardioid system will require lots of trial & error and would unfortunately mean lots and lots of labor.

What would you "fine tune"?

I can think of side-slot dimensions and position, cladding acoustic resistance properties, and back wave panel depth. Any others?

 

[TimVG]

What would you "fine tune"?

I can think of side-slot dimensions and position, cladding acoustic resistance properties, and back wave panel depth. Any others?

That's about it really. For further inspiration you could also look at some of David Gunness' (Fulcrum) patents. Truth be told an active cardioid system would be easier to implement.

 

[Absolute]

Did you ever fine-tune these things? I looked this thread up because you stated in your Genelec-ad that you were happy with your DIY efforts. I assumed these are the speakers you had in mind

 

[TimVG]

I haven't, my attention has been focussed on the Directiva R2 project. I've been using these cabinets as bass module/stands for the R2 prototype top module though

R2 has given me a lot more insight into how passive cardioid systems work though - I'm sure I could build a much better version of this speaker at the moment. Unfortunately time is scarce and need is low at the moment.

 

[Absolute]

I see. Can't wait to see the final result of that project!

Given your experience with different stuff and all kinds of EQ tunings with different speakers with different directivities, how would you rate the different factors in relative importance if you were to construct an ideal speaker?

 

[TimVG]

It's a loaded topic, and I haven't built/heard/tried everthing I want to, but here are some random thoughts

-I would first look at the nature and size of the room, and the nominal listening distance or distances in that room and work from there.

-Speakers with a narrow pattern such as this one really shine in larger rooms, to increase the direct to reflected sound ratio. I recently built some 15" coaxial full (ish) range (40hz -3dB) main monitors for a large studio room and especially in stereo this (and other) type of narrow directivity speakers can make other loudspeakers sound like toys under the right circumstances. Give them too little space and then things become less enjoyable as sounds are easily identified as coming from the left and right with an extremely clear phantom image (headhone effect). There's always a sweetspot when it comes to the ratio of direct/reflected sound.

-Keeping the beamwidth controlled (constant or steadily increasing) down to the transition frequency is never detrimental to the sound.

-There is no such thing as too neutral, yet at the same time some flaws don't bother us and aren't even noticeable until we do a proper a/b test with another speaker that doesn't feature such a flaw.

-The estimated in-room response does not predict the perceived in-room response, rather the measured response. I have tested quite different crossovers on R2 for example and in my room at least, I'm not sure I can seperate them with absolute certainty, despite the different in-room response (both estimated and measured). This because the direct sound is identical and the off-axis responses, while different, are both 'controlled'. Differences might become more obvious in different rooms or with different listening distances, this is one thing I have not been able to test yet.

-Bass matters a lot.

 

[Absolute]

Thank you for sharing your thoughts! There seems to be a shift of focus in directivity from simply controlled dispersion to constant dispersion, at least around these parts of the internet.

For me it makes intuitively sense that we would want constant directivity from around Schroeder and up, but will it subjectively be better than controlled/steadily increasing directivity?

This is the main question I hope we'll find an answer to sooner rather than later as a constant directivity design requires far more complex speaker designs or large waveguides/horns/speakers.

 

[TimVG]

Thank you for sharing your thoughts! There seems to be a shift of focus in directivity from simply controlled dispersion to constant dispersion, at least around these parts of the internet.

I'd say a more a shift from controlled from (upper) midrange up, to controlled over a wider bandwith.

For me it makes intuitively sense that we would want constant directivity from around Schroeder and up, but will it subjectively be better than controlled/steadily increasing directivity?

I agree with that completely, it is also my own gut feeling, although just like you, I'm asking myself the same question. It would need to be tested objectively in a variety of rooms to achieve meaningful data though. Constant also still has the variable of the actual beamwidth itself.

It's such a multifaceted concept that makes it quite difficult to answer that question, if there is one at all.

 

[jamescarter1982]

It's a loaded topic, and I haven't built/heard/tried everthing I want to, but here are some random thoughts

-I would first look at the nature and size of the room, and the nominal listening distance or distances in that room and work from there.

-Speakers with a narrow pattern such as this one really shine in larger rooms, to increase the direct to reflected sound ratio. I recently built some 15" coaxial full (ish) range (40hz -3dB) main monitors for a large studio room and especially in stereo this (and other) type of narrow directivity speakers can make other loudspeakers sound like toys under the right circumstances. Give them too little space and then things become less enjoyable as sounds are easily identified as coming from the left and right with an extremely clear phantom image (headhone effect). There's always a sweetspot when it comes to the ratio of direct/reflected sound.

-Keeping the beamwidth controlled (constant or steadily increasing) down to the transition frequency is never detrimental to the sound.

-There is no such thing as too neutral, yet at the same time some flaws don't bother us and aren't even noticeable until we do a proper a/b test with another speaker that doesn't feature such a flaw.

-The estimated in-room response does not predict the perceived in-room response, rather the measured response. I have tested quite different crossovers on R2 for example and in my room at least, I'm not sure I can seperate them with absolute certainty, despite the different in-room response (both estimated and measured). This because the direct sound is identical and the off-axis responses, while different, are both 'controlled'. Differences might become more obvious in different rooms or with different listening distances, this is one thing I have not been able to test yet.

-Bass matters a lot.

could we have some more info /pics of these monitors you made ? I'm Interested in making someing similar myself

 

[jzagaja]

Is it possible get cardioid passively in smaller cabinets?

 

[TimVG]

Sure. Do a search on the Directiva R2 project on this forum.