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ASR Directiva Open Source Speaker Review

thewas

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By the way for people having no access to affordable solutions there is also the passive option which costs only 50 bucks per speaker
which would be often even preferred by many people who have already good integrated or power amps.
 

fluid

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Well, I am posting my opinion to the Directiva "as a product" consistently,
This is likely where most of the confusion comes from. The Directiva at least to this point, is an open DIY design and not a product you can purchase. It would seem that there is in fact only a single speaker in existence so far, so criticism of it as a "product" is premature :)
 

Rick Sykora

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To be clear about $250 of my $1400 Directiva estimate is a minidsp 2x4 HD.

So, a crossover is included in the estimate. Prices for amps range all over and r1 does not have space for internal one.

If you put the FA253 in a external box, it would be about $700 here. So, an amplified Directiva r1 would be $1850. Hope this helps, but it is not for everyone and am ok with that. Directiva is about customization in a DIY setting. You are not limited by the someone else’s choice of amp or dsp or any other part for that matter. r1 is just the first realization of the Directiva platform. Think of it as a next gen DIY speaker platform.

If someone wants a Revel or Gelenec, they are not in the same market as Directiva. Those are proprietary products and Directiva is open source and NOT FOR COMMERCIAL USE. So, while r1 may measure favorably to proprietary commercial products, trying to make it fit the “product” mold is a pretty big stretch IMO. :)
 
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MdeVelde

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Another speaker designer here chiming in :)
I think the design would be improved by lowering the crossover freq. That tweeter can be crossed quite a bit lower. Grimm LS-1 crosses it at 1550Hz for instance.
As for the woofer, Purify has a metal cone version of this woofer now which is slightly better imo.
 

voodooless

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That tweeter can be crossed quite a bit lower. Grimm LS-1 crosses it at 1550Hz for instance.
In general, I tend to agree. In most designs, tweeter crossover is to high, letting woofer resonance through. The purify however is very clean, so one can get away with a higher X-over frequency. It’s also a matter of directivity. Question is if the lower X-over still yields smooth directivity? The LS-1 is very wide. Also at 1.55 kHz will impact tweeter power handling somewhat. Not sure the waveguide will make up for that?

It would be an interesting experiment for sure.

BTW, there seems to be a version of the DXT waveguide with a soft done as well. Haven’t seen any DIY versions of the thing, but system audio uses it in their active speaker models.
 
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samysound

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To be clear about $250 of my $1400 Directiva estimate is a minidsp 2x4 HD.

So, a crossover is included in the estimate. Prices for amps range all over and r1 does not have space for internal one.

If you put the FA253 in a box, it would be about $700 here. So, an amplified Directiva r1 would be $1850. Hope this helps, but it is not for everyone and am ok with that. Directiva is about customization in a DIY setting. You are not limited by the someone else’s choice of amp or dsp or any other part for that matter. r1 is just the first realization of the Directiva platform. Think of it as a next gen DIY speaker platform.

If someone wants a Revel or Gelenec, they are not in the same market as Directiva. Those are proprietary products and Directiva is open source and NOT FOR COMMERCIAL USE. So, while r1 may measure favorably to proprietary commercial products, trying to make it fit the “product” mold is a pretty big stretch IMO. :)
Hello, I would love to tinker with a pair of these. While I can install drivers and play with DSP options, I lack the tools and desire to build and finish cabinets. Any chance build to print drawings could be generated for the cabinet, lining/stuffing and wiring/speakeon cables such that this could be out sourced to a speaker/cabinet builder?
 

Rick Sykora

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Hello, I would love to tinker with a pair of these. While I can install drivers and play with DSP options, I lack the tools and desire to build and finish cabinets. Any chance build to print drawings could be generated for the cabinet, lining/stuffing and wiring/speakeon cables such that this could be out sourced to a speaker/cabinet builder?

Have a couple of people looking to supply cabinets or cabinet parts. Once they are available, I can build pretty readily and reasonably. Otherwise, if I have to build from scratch, my lead times are pretty long rn. ;)
 

samysound

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Have a couple of people looking to supply cabinets or cabinet parts. Once they are available, I can build pretty readily and reasonably. Otherwise, if I have to build from scratch, my lead times are pretty long rn. ;)
this is great to hear. looking forward to commissioning a pair!
 

voodooless

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Any carpenter should have an easy job making these. It’s just a box with rounded sides on the baffle. Hardest part is routing the PR on the back.
 

MdeVelde

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In general, I tend to agree. In most designs, tweeter crossover is to high, letting woofer resonance through. The purify however is very clean, so one can get away with a higher X-over frequency. It’s also a matter of directivity. Question is if the lower X-over still yields smooth directivity? The LS-1 is very wide. Also at 1.55 kHz will impact tweeter power handling somewhat. Not sure the waveguide will make up for that?

It would be an interesting experiment for sure.

BTW, there seems to be a version of the DXT waveguide with a soft done as well. Haven’t seen any DIY versions of the thing, but system audio uses it in their active speaker models.
One can't get away with a higher crossover with the Purify off-axis. Since the Purify drops off significantly off-axis while the tweeter does not.
The main benefit to crossing lower is that the vertical nulls will occur at a greater angle and you will get a smoother power response etc.
As for the waveguide, yes it will make up for it somewhat but also remember that with a proper LR4 crossover the tweeter will be -6dB at the crossover point already. Btw, I personally wouldn't bother with the soft dome DXT it's not as good (and the main breakup resonance of the metal dome DXT is above adult human hearing)
Btw I disagree the LS-1 is very wide. It is even slightly less wide than this DIY speaker as it has a wider baffle which means the mids are a bit more directional (the baffle step occurs lower in freq). Small speaker and with small metal dome tweeters without waveguide are the widest.
 

ctrl

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I think the design would be improved by lowering the crossover freq. That tweeter can be crossed quite a bit lower. Grimm LS-1 crosses it at 1550Hz for instance.
In general, I tend to agree. In most designs, tweeter crossover is to high, letting woofer resonance through. The purify however is very clean, so one can get away with a higher X-over frequency. It’s also a matter of directivity. Question is if the lower X-over still yields smooth directivity?
Unfortunately, it doesn't work that simply. Just because a tweeter can be crossed low doesn't mean it will work with any baffle.

A low crossover frequency would make the (horizontal) directivity of the Directiva r1 quite uneven, especially in the presence range (2-4kHz), because then the edge diffraction of the tweeter would come through fully.
That means either a very deep dip on-axis or a boosting of the frequency response under angle in the 2-4kHz range with linear on-axis FR.

Here is the simulated normalized horizontal frequency response of the Directiva r1 Tweeter (ignore FR above 9kHz):
1633968441302.png

For a low crossover frequency, the baffle must be optimized, as described in post#446. Then the tweeter shows good directivity down to below 2kHz.
Simulated normalized horizontal frequency response of Directiva with optimized baffle, tweeter only (ignore FR above 9kHz):
1633968540826.png

If you want to make it easier, use a large waveguide, but many don't like that for aesthetic reasons and then it would be a completely different speaker.


You can download the full VCAD project here, try different things and see the effects immediately.


Grimm LS-1 crosses it at 1550Hz for instance.
The just described effect of the edge diffraction on the frequency response of the tweeter can be observed very nicely in the measurements of the Grimm LS1, where the sound pressure level of the horizontal 45° frequency response coincides or even exceeds the on-axis sound pressure level in the range below 3kHz.
1633969167549.png
Source: https://www.hifitest.de/images/testbilder/big/grimm-audio-ls1-lautsprecher-stereo-17246.jpg
 

MdeVelde

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Unfortunately, it doesn't work that simply. Just because a tweeter can be crossed low doesn't mean it will work with any baffle.

A low crossover frequency would make the (horizontal) directivity of the Directiva r1 quite uneven, especially in the presence range (2-4kHz), because then the edge diffraction of the tweeter would come through fully.
That means either a very deep dip on-axis or a boosting of the frequency response under angle in the 2-4kHz range with linear on-axis FR.

Here is the simulated normalized horizontal frequency response of the Directiva r1 Tweeter (ignore FR above 9kHz):
View attachment 158428

For a low crossover frequency, the baffle must be optimized, as described in post#446. Then the tweeter shows good directivity down to below 2kHz.
Simulated normalized horizontal frequency response of Directiva with optimized baffle, tweeter only (ignore FR above 9kHz):
View attachment 158429

If you want to make it easier, use a large waveguide, but many don't like that for aesthetic reasons and then it would be a completely different speaker.


You can download the full VCAD project here, try different things and see the effects immediately.



The just described effect of the edge diffraction on the frequency response of the tweeter can be observed very nicely in the measurements of the Grimm LS1, where the sound pressure level of the horizontal 45° frequency response coincides or even exceeds the on-axis sound pressure level in the range below 3kHz.
View attachment 158434
Source: https://www.hifitest.de/images/testbilder/big/grimm-audio-ls1-lautsprecher-stereo-17246.jpg
Well then make a bigger roundover and change the baffle size if needed?
I personally don't feel one should ignore the vertical off-axis and power response to the benefit of perfecting only the horizontal off-axis.
Crossing lower if the tweeter allows it (and the DXT does) and optimising the baffle for this will give a better overall end result in my personal opinion.

edit: btw I've designed a wide speaker with PVC tube halves at the sides and top in the past. It's doable DIY and would solve edge diffraction almost completely. (never built that speaker though as I got exited about a very different design, building an omni speaker currently)

edit2: btw one other thing to watch for is that Vituixcad tends to exaggerate diffraction effects. It assumes a baffle/speaker with 0 depth. Real life measurements tend to show less diffraction. Always measure in real-life too.
 
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Rick Sykora

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Well then make a bigger roundover and change the baffle size if needed?
I personally don't feel one should ignore the vertical off-axis and power response to the benefit of perfecting only the horizontal off-axis.
Crossing lower if the tweeter allows it (and the DXT does) and optimising the baffle for this will give a better overall end result in my personal opinion.
In the spirit of Directiva, feel free to take what we have done in r1 and modify it according to your preferences. Except for some possible small crossover tweaks, r1 is a done design. If we modify it much more, it would no longer match what Amir reviewed. :)
 

MdeVelde

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In the spirit of Directiva, feel free to take what we have done in r1 and modify it according to your preferences. Except for some possible small crossover tweaks, r1 is a done design. If we modify it much more, it would no longer match what Amir reviewed. :)
Ah cool. I didn't realise that it is a done design :)
Very good design indeed at an amazing price point! I had been working on something similar (though a 3-way active design) and it would have cost somewhere around 3000 to make a pair.
 

amper42

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Part of the concept was that R1 should based around a readily available denovo flatpack. Hence the 'set' dimensions.
What is the link to the denovo flatpack? Thanks!
 

mdsimon2

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What is the link to the denovo flatpack? Thanks!

Parts list can be found at link below.


Direct link to flat pack below.


As an aside I've built 2 subwoofers and 2 towers using Denovo flat packs and I really like them. I was a bit worried about shipping damage but I have had no issues with that. They really simplify the building process and assuming you have enough clamps they are very easy to build without any fasteners (glue only). As has been discussed a few times you will need to router holes for the drivers, passive radiator and your preferred binding posts / connectors but if you have a router and a some scrap material it is very easy to give it a few practice attempts and dial it in before completing the final routing.

Michael
 

gab

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Well then make a bigger roundover and change the baffle size if needed?


edit: btw I've designed a wide speaker with PVC tube halves at the sides and top in the past. It's doable DIY and would solve edge diffraction almost completely. (never built that speaker though as I got exited about a very different design, building an omni speaker currently)

 

bluefuzz

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no off-the-shelf cabinet could have been used, so this option was also discarded
If I'm not mistaken the Denovo cabinet is only 'off-the-shelf' in the USA. Buying this cabinet and having it shipped to Europe, for example, would probably cost nearly as much as getting a similar cabinet custom built by a local cabinetmaker. And really, if someone can't cut six pieces of MDF square and glue them together they probably shouldn't be considering DIY in the first place. Since the majority of ASR members are not in the USA, the off-the-shelf requirement of Directiva is a bit unnecessary IMO as most potential builders will be building from scratch anyway ...
 
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