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ASR Directiva Open Source Speaker Review

amirm

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As some of you know, we have had a project to design an open-source speaker based on Purifi driver. It has been led by our member, @Rick Sykora who has named it "Directiva." You can read about it here: https://www.audiosciencereview.com/...r-open-source-platform-speaker-project.20407/

The idea came about from a hypothesis: if a speaker design had access to Klippel Near-field scanner, would he be able to design a super speaker? I own the speaker but I am not a speaker designer so it made sense to have others help create one. The results of that work is now here in the form of a prototype built by Rick with much help on design side from member @ctrl.

Other than the crinkled woofer from Purifi, there is not much to distinguish this speaker from any other DIY prototype:

ASR Directiva Review Open Source Purifi Speaker.jpg


I let Rick chime in with the choice of tweeter. On the back side, we have an SB Acoustics passive radiator:

ASR Directiva Review Open Source Purifi passive radiator Speaker.jpg


My understanding is that a traditional port design is difficult for the Purifi driver and hence the use of the radiator.

Connectivity is provided through a SpeakOn connector which provides dual set of inputs, one for tweeter and one for woofer.

This is an active design so I build a compact system to drive it comprising of the Minidsp 2x4 HD and SMSL VMV A2 desktop amplifier. The combination sat on top of the speaker with a pad under it. It was actually a bit smaller than it which helped with not creating diffraction error or changing baffle compensation.

Two scans were performed with the second one employing minor refinements.

ASR Directiva Measurements
Here is our spin graph:

ASR Directiva Measurement Frequency Response Open Source Purifi Speaker.png


I must say, the flatness of the on-axis response put a big smile on my face. I am only used to seeing such an accurate response when measuring DSP based active monitors. Not only that, the early window directivity mirrors the on-axis smoothly and only has a minor dip between 2 and 3 kHz.

Drilling into the early window reflections, we see that it is the vertical axis that is responsible for that dip:

ASR Directiva Measurement Early Window Frequency Response Open Source Purifi Speaker.png


Hard to do much better without a coaxial driver. Fortunately the floor is most responsible for that so as usual, put a thick rug there and you should be able to get better response than that. Assuming you don't do that, you still get a very nice predicted in-room frequency response:

ASR Directiva Measurement Predicted In-room Frequency Response Open Source Purifi Speaker.png

Driver and radiator response is clean:

ASR Directiva Measurement Driver Response Open Source Purifi Speaker.png


Maybe having a little filter to pull that bump above 10 kHz down a couple of dBs but likely won't be audible.

Our beamwidth measurement is excellent:

ASR Directiva Measurement horizontal beam width Open Source Purifi Speaker.png


There is slight narrowing but we need that to keep the speaker from sounding too bright as it lights up all surfaces otherwise.

Horizontal directivity as a result looks pretty:

ASR Directiva Measurement horizontal directiva Open Source Purifi Speaker.png


We have the usual non-perfect vertical directivity but it is better than many 2-way speakers:

ASR Directiva Measurement Vertical directiva Open Source Purifi Speaker.png


This is a speaker that is room friendly.

CSD/Waterfall shows some resonances:

ASR Directiva Measurement CSD Waterfall Open Source Purifi Speaker.png


Some of this could be because of the DSP and and amp being on top of the amp as the enclosure feels solid as a rock.

We see more evidence of the resonances in distortion measurements which otherwise are excellent:

ASR Directiva Measurement THD Distortion Open Source Purifi Speaker.png


ASR Directiva Measurement Distortion Open Source Purifi Speaker.png


Directiva Listening Tests
These days it takes me so little time to tell if overall tonality is right. And such was the case here. I felt no need to reach for EQ although at times I thought upper bass was a bit weak. I think speakers with distortion generate harmonics that land in that region. Take that away and the perception is a cleaner but slightly leaner upper bass. I am emphasizing upper bass as Directiva was able to deliver good bit of sub-bass. I didn't want to mess with EQ as you really need to measure the room+speaker response and correct for that.

The sound was very clean, making me want to really crank up the volume. When I pushed that hard, I could sometimes hear a bit of ticking sound. I am not sure if the the minidsp was saturating its input or the driver was the issue. By then the volume was pretty loud and with two speakers you would be fine.

I tested for tweeter hiss and unfortunately it was bad in this configuration. I could easily hear it up to about 2 feet away. Minidsp supports Toslink and ideally you would be using that input and avoid its ADC and my pre-amp. That would have required me ripping out my listening room even more so I did not go there. Fortunately unlike powered monitors, with a kit like this, you can play with such options (and amplification) to get the best noise and power capability you need.

DIY Build Cost
Rick tells me that the cost for the components to build a pair is about US $1,300 to $1,400. A commercial implementation with fancy finish and such would then land at $4K to $5K rang which would be pretty expensive given the lack of DSP and amplification cost on top of that. For DIY though, it makes sense.

Conclusions
Well, the hypothesis is proven: get a few smart people together and give them a Klippel NFS measurement system and they too can produce world-class speaker performance. I am very pleased with how the project has come out, showing the power of the community to come together to follow the best in science, engineering and simulation technology. Thanks to all of you who contributed. I am proud of you all!

P.S. Just in case @MZKM is sleep right now, he was kind enough to give me his preference scores:

Preference Rating
SCORE: 6.5
SCORE w/ sub: 8.0

Frequency response: +/- 1.9dB 40Hz-20kHz
LFX: 34Hz

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Wortifer

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Fantastic results! I've been watching this and the ASR streamer projects from the beginning and anxiously awaiting the outcome. This is only going to get better as users start adding their own twists. I plan on conceptualizing and building something like this with fusion amps.

Congratulations @Rick Sykora , @ctrl & @amirm
 

richard12511

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As some of you know, we have had a project to design an open-source speaker based on Purifi driver. It has been led by our member, @Rick Sykora who has named it "Directiva." You can read about it here: https://www.audiosciencereview.com/...r-open-source-platform-speaker-project.20407/

The idea came about from a hypothesis: if a speaker design had access to Klippel Near-field scanner, would he be able to design a super speaker? I own the speaker but I am not a speaker designer so it made sense to have others help create one. The results of that work is now here in the form of a prototype built by Rick with much help on design side from member @ctrl.

Other than the crinkled woofer from Purifi, there is not much to distinguish this speaker from any other DIY prototype:

View attachment 157072

I let Rick chime in with the choice of tweeter. On the back side, we have a purifi passive radiator:

View attachment 157073

My understanding is that a traditional port design is difficult for the Purifi driver and hence the use of the radiator.

Connectivity is provided through a SpeakOn connector which provides dual set of inputs, one for tweeter and one for woofer.

This is an active design so I build a compact system to drive it comprising of the Minidsp 2x4 HD and SMSL VMV A2 desktop amplifier. The combination sat on top of the speaker with a pad under it. It was actually a bit smaller than it which helped with not creating diffraction error or changing baffle compensation.

Two scans were performed with the second one employing minor refinements.

ASR Directiva Measurements
Here is our spin graph:

View attachment 157074

I must say, the flatness of the on-axis response put a big smile on my face. I am only used to seeing such an accurate response when measuring DSP based active monitors. Not only that, the early window directivity mirrors the on-axis smoothly and only has a minor dip between 2 and 3 kHz.

Drilling into the early window reflections, we see that it is the vertical axis that is responsible for that dip:

View attachment 157075

Hard to do much better without a coaxial driver. Fortunately the floor is most responsible for that so as usual, put a thick rug there and you should be able to get better response than that. Assuming you don't do that, you still get a very nice predicted in-room frequency response:

View attachment 157076
Driver and radiator response is clean:

View attachment 157078

Maybe having a little filter to pull that bump above 10 kHz down a couple of dBs but likely won't be audible.

Our beamwidth measurement is excellent:

View attachment 157077

There is slight narrowing but we need that to keep the speaker from sounding too bright as it lights up all surfaces otherwise.

Horizontal directivity as a result looks pretty:

View attachment 157079

We have the usual non-perfect vertical directivity but it is better than many 2-way speakers:

View attachment 157080

This is a speaker that is room friendly.

CSD/Waterfall shows some resonances:

View attachment 157081

Some of this could be because of the DSP and and amp being on top of the amp as the enclosure feels solid as a rock.

We see more evidence of the resonances in distortion measurements which otherwise are excellent:

View attachment 157082

View attachment 157083

Directiva Listening Tests
These days it takes me so little time to tell if overall tonality is right. And such was the case here. I felt no need to reach for EQ although at times I thought upper bass was a bit weak. I think speakers with distortion generate harmonics that land in that region. Take that away and the perception is a cleaner but slightly leaner upper bass. I am emphasizing upper bass as Directiva was able to deliver good bit of sub-bass. I didn't want to mess with EQ as you really need to measure the room+speaker response and correct for that.

The sound was very clean, making me want to really crank up the volume. When I pushed that hard, I could sometimes hear a bit of ticking sound. I am not sure if the the minidsp was saturating its input or the driver was the issue. By then the volume was pretty loud and with two speakers you would be fine.

I tested for tweeter hiss and unfortunately it was bad in this configuration. I could easily hear it up to about 2 feet away. Minidsp supports Toslink and ideally you would be using that input and avoid its ADC and my pre-amp. That would have required me ripping out my listening room even more so I did not go there. Fortunately unlike powered monitors, with a kit like this, you can play with such options (and amplification) to get the best noise and power capability you need.

DIY Build Cost
Rick tells me that the cost for the components to build a pair is about US $1,300 to $1,400. A commercial implementation with fancy finish and such would then land at $4K to $5K rang which would be pretty expensive given the lack of DSP and amplification cost on top of that. For DIY though, it makes sense.

Conclusions
Well, the hypothesis is proven: get a few smart people together and give them a Klippel NFS measurement system and they too can produce world-class speaker performance. I am very pleased with how the project has come out, showing the power of the community to come together to follow the best in science, engineering and simulation technology. Thanks to all of you who contributed. I am proud of you all!

P.S. Just in case @MZKM is sleep right now, he was kind enough to give me his preference scores:

Preference Rating
SCORE: 6.5
SCORE w/ sub: 8.0

Frequency response: +/- 1.9dB 40Hz-20kHz
LFX: 34Hz

index.php
Damn, that looks really good.
 

617

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Great effort but the value, apart from having fun building it, is not there. A pair of Genelecs 8040 will be cheaper and at least as good.
My hope from this review would be that the purefi woofer would somehow distinguish itself in terms of bass or output but this review doesn't seem to indicate anything special. Curious of other impressions.
 

xykreinov

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Wow, epic speaker. I would even argue the value is there. Yes, other powered monitors in this price bracket give you a similar frequency response graph. But, as good bass extension, low distortion, and compactness at the same time? Rarely. I'm no speaker designer, but those peaks in the distortion graph look very fixable- likely only problems with the gear on top, as Amir suspected. I bet a lot it's just the MiniDSP unit.
If MiniDSP made a device with the performance of the SHD with the small footprint of the 2x4, the Directiva would really kick butt and take names.
 
Last edited:

Sancus

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My hope from this review would be that the purefi woofer would somehow distinguish itself in terms of bass or output but this review doesn't seem to indicate anything special. Curious of other impressions.
Well distortion above 100hz is definitely very low, I think it's lower than anything measured so far that is 1x8" or smaller. Especially for 3rd+ harmonic.
 

mcdn

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My hope from this review would be that the purefi woofer would somehow distinguish itself in terms of bass or output but this review doesn't seem to indicate anything special. Curious of other impressions.
Sure, maybe it's not, but it's got a flat response and THD below 5% from 40Hz upwards at 86dBSPL, in a small package. Can you point to other speaker measurements that cause you to say it's not special?
 

YSC

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This looks amazing until I saw the price, now time to go back to genelec and Neumann with my bank account
 

Shazb0t

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Curious about those large distortion spikes at 96dB THD.
 

richard12511

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My hope from this review would be that the purefi woofer would somehow distinguish itself in terms of bass or output but this review doesn't seem to indicate anything special. Curious of other impressions.

I don't know, it seems like maybe the best distortion performance we've seen from something this size, especially if we can figure out the cause of those spikes. Also, great extension and Genelec like neutrality. At the build price, it looks SOTA.
 

restorer-john

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Interesting review. :)

I'm not sure what to make of it however. Has it been EQ'd in DSP within an inch of its life and if so, why the obvious hole in the response, at the crossover point, dead in the most important part of the midrange?
 

ROOSKIE

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Interesting results, very, very, very good looking DIY kit. (and helps me feel more confident that my own 2 way active designs might actually sound as good as I think they do.)
Hmmm, I am still not that over impressed with the purifi in terms of the on paper measurements here when contrasted with the price. Though I have never heard the woofer or any system using it. It is fairly expensive. Out of curiosity why this woofer? I am betting it was to prove it can be done right.
 
Last edited:

ROOSKIE

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Curious about those large distortion spikes at 96dB THD.
Based on the charts I'd say something was vibrating or loose. *Like amir said maybe the amps sitting on top) Not likely from the transducers.
 
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