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Introducing Directiva - An ASR open source platform speaker project

fluid

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The radiation from the speaker remains the same but the response at the listening position will change depending on the distance to the walls. Most cardioid speakers have high rear rejection so the wall behind the speaker is less of an issue, but still wide horizontal directivity so close side walls are a problem as they are for any speaker without very high horizontal directivity.

In a very compromised position absorption to the sides and cardioid to help with the rear wall is a good option to deal with boundary effects.
Simulations can help ball park the effects based on distances.

https://www.audiosciencereview.com/forum/index.php?threads/dutch-dutch-8c-review.21016/post-989007

https://www.audiosciencereview.com/forum/index.php?threads/dutch-dutch-8c-review.21016/post-990590
 

muad

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The radiation from the speaker remains the same but the response at the listening position will change depending on the distance to the walls. Most cardioid speakers have high rear rejection so the wall behind the speaker is less of an issue, but still wide horizontal directivity so close side walls are a problem as they are for any speaker without very high horizontal directivity.

In a very compromised position absorption to the sides and cardioid to help with the rear wall is a good option to deal with boundary effects.
Simulations can help ball park the effects based on distances.

https://www.audiosciencereview.com/forum/index.php?threads/dutch-dutch-8c-review.21016/post-989007

https://www.audiosciencereview.com/forum/index.php?threads/dutch-dutch-8c-review.21016/post-990590
I was more wondering at what point will side reflections disrupt the cardioid effect?
 

fluid

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I was more wondering at what point will side reflections disrupt the cardioid effect?
They have the same influence as any speaker, a cardioid has reduced rear hemisphere output, by 90 degrees they tend to have a wide pattern and no real immunity from side wall reflections interfering.
 

sonicboomer

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Hey Folks, Nice progress on the r2 project. I was also attempting a similar build, a 3-way poor-man's kef blades (was unaware of the progress on the r2). I'm using a dedicated midrange (SB12MNRX2-25-04) passively crossed over with the same DXT tweeter as the Directiva, and actively crossed over with a couple of side firing dual opposing oval sb acoustics woofers (SB15SFCR39).
I'm leaning on minidsp to fill in any baffle losses, flatten response, help with time alignment and room correction. Here is a crossover I worked on, with manufacturer supplied data (diyaudio post).
I'm almost at the point of getting a cabinet cnc'd. I'm planning for a compact sealed tower (~30l) that works in my living space.
1645999811514.png
1645999835095.png
1645999757062.png

Now that I saw the progress on this design, I'm curious about the team's thoughts on my design choices. Since I'm a beginner, I'm nervous about going ahead with my design while I can just wait and build the r2.
  • The midrange driver seems to have slightly better sensitivity at the expense of bass extension. I'm planning to crossover a bit higher, and expect the bass unit to take over below 200-300hz. If 3 way is the end goal, would you still use a midwoofer over a dedicated midrange? Am I chasing efficiency at the expense of something?
  • Are side firing woofers capable of delivering the cardioid dispersion pattern? Just with the ability to control timing using minidsp2x4HD? Is a single point source not a thing worth going after?
If y'all don't think this is the place for this post, let me know and I can move this.
 

alex-z

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Here is a crossover I worked on, with manufacturer supplied data (diyaudio post).

  • Are side firing woofers capable of delivering the cardioid dispersion pattern? Just with the ability to control timing using minidsp2x4HD? Is a single point source not a thing worth going after?
Manufacturer data can bite you quickly. The large IEC baffles they use for testing behave much differently than a normal speaker baffle. Get a test cabinet, measure the drivers in-situ before buying any passive crossover components.

The side woofers can only deliver cardoid radiation in the area overlapped with the mid-range. The phase relationship between the energy escaping the front and sides is what creates the effect.

If you want a true poor mans KEF Blade, buy a pair of LS50 Meta and take the coaxial drive units for use in your project. Then the vertical directivity will be just as good as the horizontal. Or Q150 drive units for an even poorer KEF Blade.
 

fluid

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  • Are side firing woofers capable of delivering the cardioid dispersion pattern? Just with the ability to control timing using minidsp2x4HD? Is a single point source not a thing worth going after?
Side woofers can provide cardioid like directivity but there has to be an overlap between the mid and woofer in order for the woofer to provide cancellation to the mid further off axis.
If y'all don't think this is the place for this post, let me know and I can move this.
If you want help with the design start a new thread or build an R2 when the development has been completed.
 

sonicboomer

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Thanks for taking time to reply, @fluid and @alex-z. I’ll also contemplate the next steps, whether to go with a coaxial or if the directivity is good enough for the listening window. I’ll subscribe to the r2 threads and will post in a new thread if I pursue my 3 way design.
 

Nwickliff

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Manufacturer data can bite you quickly. The large IEC baffles they use for testing behave much differently than a normal speaker baffle. Get a test cabinet, measure the drivers in-situ before buying any passive crossover components.

The side woofers can only deliver cardoid radiation in the area overlapped with the mid-range. The phase relationship between the energy escaping the front and sides is what creates the effect.

If you want a true poor mans KEF Blade, buy a pair of LS50 Meta and take the coaxial drive units for use in your project. Then the vertical directivity will be just as good as the horizontal. Or Q150 drive units for an even poorer KEF Blade.
I used the q100 in my open baffle design with a couple of grs 15 in drivers crossed at 275hz. Great little driver and made top end xo super easy. Just two parts I had lying around. Bottom half is active and top 2 way is eq’d but not actively crossed over.
 

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Rick Sykora

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Hey Folks, Nice progress on the r2 project. I was also attempting a similar build, a 3-way poor-man's kef blades (was unaware of the progress on the r2). I'm using a dedicated midrange (SB12MNRX2-25-04) passively crossed over with the same DXT tweeter as the Directiva, and actively crossed over with a couple of side firing dual opposing oval sb acoustics woofers (SB15SFCR39).
I'm leaning on minidsp to fill in any baffle losses, flatten response, help with time alignment and room correction. Here is a crossover I worked on, with manufacturer supplied data (diyaudio post).
I'm almost at the point of getting a cabinet cnc'd. I'm planning for a compact sealed tower (~30l) that works in my living space.

Now that I saw the progress on this design, I'm curious about the team's thoughts on my design choices. Since I'm a beginner, I'm nervous about going ahead with my design while I can just wait and build the r2.
  • The midrange driver seems to have slightly better sensitivity at the expense of bass extension. I'm planning to crossover a bit higher, and expect the bass unit to take over below 200-300hz. If 3 way is the end goal, would you still use a midwoofer over a dedicated midrange? Am I chasing efficiency at the expense of something?
  • Are side firing woofers capable of delivering the cardioid dispersion pattern? Just with the ability to control timing using minidsp2x4HD? Is a single point source not a thing worth going after?
If y'all don't think this is the place for this post, let me know and I can move this.

Sorry if a bit candid, but a 3-way speaker is challenge for even more experienced designers. You might get some decent results eventually but will require a lot of patience. If you have not already, suggest you read Linkwitz's beginner advice on his website.

The Directiva team is a bit stretched right now and though you chose the DXT and a comparable cabinet, it is another design in its own right. As such, would require a significant design effort. As suggested, if you still want to pursue, start another thread and will help as time allows.

If you are willing to learn, do not want to discourage you. Just want you to be aware that you are attempting a complex design and it may be a longer journey than you anticipate. Directiva r2 or an established small tower design are better choices for a newbie. Might want to take a look at this thread: https://www.audiosciencereview.com/...-compact-tower-speakers-recommandation.31025/
 

TheBatsEar

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Well, i'm about to give up on the Directiva. It's just so frustrating to collect and guess the information on how it was built, what the decisions for this or that where, BOM and so on.

Is there anyone that built the speaker measured by Amir that wasn't on the development team? I mean, it could be just me and my scatter brain. :rolleyes:
 

TimVG

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Well, i'm about to give up on the Directiva. It's just so frustrating to collect and guess the information on how it was built, what the decisions for this or that where, BOM and so on.

Is there anyone that built the speaker measured by Amir that wasn't on the development team? I mean, it could be just me and my scatter brain. :rolleyes:


Perhaps the build thread would be of help to you
 

TheBatsEar

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Rick Sykora

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While seemingly way overdue, I posted the r1 build link at the start of this thread. :)
 
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Rick Sykora

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ernestcarl

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I used the q100 in my open baffle design with a couple of grs 15 in drivers crossed at 275hz. Great little driver and made top end xo super easy. Just two parts I had lying around. Bottom half is active and top 2 way is eq’d but not actively crossed over.

Any reason why you decided to put the concentric driver on the same left side?
 

Nwickliff

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Any reason why you decided to put the concentric driver on the same left side?
Was a complete oversight. I made the second baffle so far apart from the first since I was testing just one baffle for design. Also made the flush mount hole too large, didn’t use raking light or mineral oil to check for scratches before staining, so stained twice which ended up darker than I wanted. I figured I’d just take them to completion no matter the mistakes I made and make a version 2.0 with everything I learned later down the road.
 

TimVG

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Short answer: not really, I wish it were that simple :)
Without giving away too much - we're working on something that can be coupled to a sub. I'm upgrading my measurement system at the moment and we're all switching to ARTA as well, so we'll a need a bit more of your patience until we're sure our data is as reliable as possible.
 

abdo123

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Short answer: not really, I wish it were that simple :)
Without giving away too much - we're working on something that can be coupled to a sub. I'm upgrading my measurement system at the moment and we're all switching to ARTA as well, so we'll a need a bit more of your patience until we're sure our data is as reliable as possible.
That's cool to hear!

I just meant it that the driver would have enough displacement (a la Dutch & Dutch 8C) and can still be crossed around ~2KHz so there is no need for larger tweeters with waveguides.

Ofcourse there will always be need for a crossover somewhere because from what I collected the excursion needed would be insane below 100Hz anyway.
 
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