Introducing Directiva - An ASR open source platform speaker project

[D!sco]

The depth of the cabinet does not play a decisive role in the Directiva r2, but still contributes to the radiation pattern.

If you really plan to build a bookshelf speaker with a significantly greater depth, the radiation pattern will change somewhat.
When the time comes you can contact me, then I can simulate for you how big the effects will be compared to the original r2.

Update: Of course only if your design is open source again

Hahaha, maybe I'll sell it. You never know! The Directiva team has done some stellar work so far, a lot of it looks at least as good as many professional examples. With some work and marketing, they could compete with some serious products. I have no doubt that monitor would have similar value.

I'd love to learn what makes a cardioid enclosure tick, especially since I'm hoping to use these techniques in the future. My first goal would be to see if it works in a PVC pipe, the easiest enclosure to fabricate. Maybe a 3D printed cardioid cone enclosure after. This is a cool project to watch.

 

[Martyreasoner]

A quick visualization of bass module sizes, assuming a desired 43" tweeter height (110 cm)

View attachment 180209

From left to right: 4x 15cm" drivers, 2x 17cm drivers, 1 x 23cm, 2 x 23 cm, 1 x 27cm, 1 x 12".

Interesting. What are the proposed rear driver configs for cardioid. Also are we assuming this will be ran off of a hypex plate amp?

 

[thunderchicken]

A quick visualization of bass module sizes, assuming a desired 43" tweeter height (110 cm)

View attachment 180209

From left to right: 4x 15cm" drivers, 2x 17cm drivers, 1 x 23cm, 2 x 23 cm, 1 x 27cm, 1 x 12".

I think the 2x23cm version is ultimately what I'd go with, but I'm thinking WAF will be pretty high with the 2x17cm and 4x15cm versions.

 

[TimVG]

For those wondering what R2 with a bass module may look like on paper. My own midbass/mid cabinet (avatar) which is used in combination with a narrow directivity horn will serve as bass cabinet for the time being while I evaluate crossover and voicing configurations (for my own use). It laso features a somewhat controlled behaviour at lower frequencies, although it was my first attempt at such a model and it's not as good as I could make one now. I cross to my subs at 80 or so Hz.

I luckily still had the anechoic measurements from my bass cabinet, in combination with the R2 top module (a minor adjustment in baffle step is not visualised as they were not measured as such) we get the following:

 

[digitalfrost]

 

[D!sco]

A perfect sub crossover point, to boot.

 

[Lbstyling]

For those wondering what R2 with a bass module may look like on paper. My own midbass/mid cabinet (avatar) which is used in combination with a narrow directivity horn will serve as bass cabinet for the time being while I evaluate crossover and voicing configurations (for my own use). It laso features a somewhat controlled behaviour at lower frequencies, although it was my first attempt at such a model and it's not as good as I could make one now. I cross to my subs at 80 or so Hz.

I luckily still had the anechoic measurements from my bass cabinet, in combination with the R2 top module (a minor adjustment in baffle step is not visualised as they were not measured as such) we get the following:

View attachment 181006

View attachment 181007

Nice!

I assume the DI peak at crossover cannot practically be improved further as its a C to C spacing issue. If this is correct, is it possible to router into the edge of the horn so the bass driver can get closer?

 

[TimVG]

I'd like to premise by stating this is not the final crossover, just a visualisation of what I'm currently trying.

is it possible to router into the edge of the horn so the bass driver can get closer?

Not an option, sorry. Fwiw this kind of thing is not going to be audible in the slightest, there's no hint of a dip in the direct sound or even up to (and beyond) +/-10°.

It's funny as I expected this would come up at one point. I even discussed it with the other team members some time ago: Do we design for the best looking spinorama and estimated in-room response to avoid discussion, or move against this if we feel it makes for a better practical loudspeaker.

We could design it as such that the peak is gone completely, even in the DI. You have to remember though that these are averages, once we start looking at the individual curves then you'll start to see other anomalies, such as a peak around crossover above or below the acoustical axis, meaning a timbral shift as you move up and down. The closer you are the more pronounced this could be. This particular configuration as it is now however, has quite a large vertical window as well.

This is my take on it, the team will decide together on a final crossover, and it could very well be quite different from this one, I don't know yet.
Just be aware that a perfect spinorama doesn't always mean a better practical result (although the spinorama looks pretty nice as it is).

 

[fluid]

Nice!

I assume the DI peak at crossover cannot practically be improved further as its a C to C spacing issue. If this is correct, is it possible to router into the edge of the horn so the bass driver can get closer?

Splitting a waveguide with a woofer to narrow the CTC distance can have quite a negative effect on the performance of the waveguide. If you can't get the drivers within a 1/3 WL distance or closer often the best trade off position is then further away. Unless you are trying to create interference from the 0.5 to 0.7 wavelength spacing those distances are best avoided.

Example from here shown below
https://www.diyaudio.com/community/...aker-build-abec-modelling.357792/post-6492454

 

[abdo123]

@TimVG

You forgot to mention the most important thing, how does it sound?

 

[TimVG]

@TimVG

You forgot to mention the most important thing, how does it sound?

Well I don't know yet, haven't had time to plug them in. With a little bit of luck, tomorrow.

 

[Lbstyling]

I'd like to premise by stating this is not the final crossover, just a visualisation of what I'm currently trying.



Not an option, sorry. Fwiw this kind of thing is not going to be audible in the slightest, there's no hint of a dip in the direct sound or even up to (and beyond) +/-10°.

It's funny as I expected this would come up at one point. I even discussed it with the other team members some time ago: Do we design for the best looking spinorama and estimated in-room response to avoid discussion, or move against this if we feel it makes for a better practical loudspeaker.

We could design it as such that the peak is gone completely, even in the DI. You have to remember though that these are averages, once we start looking at the individual curves then you'll start to see other anomalies, such as a peak around crossover above or below the acoustical axis, meaning a timbral shift as you move up and down. The closer you are the more pronounced this could be. This particular configuration as it is now however, has quite a large vertical window as well.

View attachment 181062

This is my take on it, the team will decide together on a final crossover, and it could very well be quite different from this one, I don't know yet.
Just be aware that a perfect spinorama doesn't always mean a better practical result (although the spinorama looks pretty nice as it is

Splitting a waveguide with a woofer to narrow the CTC distance can have quite a negative effect on the performance of the waveguide. If you can't get the drivers within a 1/3 WL distance or closer often the best trade off position is then further away. Unless you are trying to create interference from the 0.5 to 0.7 wavelength spacing those distances are best avoided.

Example from here shown below
https://www.diyaudio.com/community/...aker-build-abec-modelling.357792/post-6492454

Well well, Learned something today!

This is not how I understood it works, but makes total sense given some experience with room nodes.

Thank you!

 

[abdo123]

Well I don't know yet, haven't had time to plug them in. With a little bit of luck, tomorrow.

I meant the small module on its own by the way, but indeed it makes more sense to test with more bass, cardioid or not.

 

[TimVG]

I meant the small module on its own by the way, but indeed it makes more sense to test with more bass, cardioid or not.

Oh just once really with a quick, on the spot, experimental crossover - basically just focussed on the on-axis. Sounded pretty good!

In fact you can check it out here:

 

[abdo123]

Oh just once really with a quick, on the spot, experimental crossover - basically just focussed on the on-axis. Sounded pretty good!

In fact you can check it out here:

Thank you for sharing! I love these moving videos that you do with your cardiods hahaha.

Truth be told it's difficult for anything to sound band in such a space .

 

[TimVG]

Thank you for sharing! I love these moving videos that you do with your cardiods hahaha.

Truth be told it's difficult for anything to sound band in such a space .

Oh I guarantee you i've had plenty of bad stuff passing here

In all honesty it did sound quite good, and I may be underselling that a bit at the moment, but I need to check them out in my listening space first. Perhaps I should say they sound as good as the measurements indicate they should.

 

[Lbstyling]

Oh just once really with a quick, on the spot, experimental crossover - basically just focussed on the on-axis. Sounded pretty good!

In fact you can check it out here:

I can't remember the effect of the direct Vs reflected sound in any other demo video being quite so obvious a transition as when you walk back in this video.

Also notable lack of 'boomyness' as you walk round (as expected I suppose!)

I would be I tested to see the distortion figures also.

It's looking like a mighty strong design.

 

[617]

@TimVG I'm not sure if we've discussed it privately but what are your impressions of output/distortion/ stress testing?

 

[TimVG]

I tested the top module without a high pass on some bass heavy tracks, and while there was no real output in the low range, and quite a bit of driver movement, I could not detect any audible distortion. I'm going to fire them up tomorrow in a 3-way configuration and see what happens. My horns are as dynamic as they come so it should be interesting.

 

[Newman]

...For those who might be surprised by the number of versions, along with different midwoofers, gave waveguides a shot too. ...

Hi Rick,

could you perhaps edit post #1 from time to time, so that it starts with links to the posts in the thread that represent the 'most current' design details for this project?

If not, can you point me to the key posts please?

I have quite lost track.

cheers