ASR Directiva Open Source Speaker Review

[Rick Sykora]

Thanks for the write-up, Rick!


So your starting point was already chosen so that the budget goal was already hard to reach? Luckily the excellent tweeter is budget-friendly Also, this budget does not include the active parts, does it? Amir's amplifier already costs $999, and you need two of them. Obviously cheaper options are available

One could probably shoehorn a Hypex MC and miniDSP in a small base to make a compact full contained unit. Or you could build it into a stand.. lots of options really.

The budget does not include the amps for a couple of reasons, both are cost related. First, the cost comparison to passive design is better aligned as the cost of a minidsp HD and a good passive crossover are comparable. Two, too many amplifier considerations would create a (confusing) large deviation in the cost.

I acknowledge that some would argue that the minidsp HD is not good enough either. It does offer good price/performance though. Am open to other options too, but may have to wait for r2 or someone else to provide a good alternative.

 

[abdo123]

The budget does not include the amps for a couple of reasons, both are cost related. First, the cost comparison to passive design is better aligned as the cost of a minidsp HD and a good passive crossover are comparable. Two, too many amplifier considerations would create a (confusing) large deviation in the cost.

I acknowledge that some would argue that the minidsp HD is not good enough either. It does offer good price/performance though. Am open to other options too, but may have to wait for r2 or someone else to provide a good alternative.

The Hypex Fusion Amplifiers are a steal, but you would be limited to 3 dedicated amplified channels.

I kind of also would like to keep the Purifi Woofer only because i want the design to have zero compromises for my own selfish reasons .

 

[Spocko]

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.

So now here comes the fun part - what if you stripped down the "exotic" driver materials to the cheapest available leaving only the barest system essentials: active DSP, box dimensions and shape. How close does the cheapest possible version get to the original? Probably can't reach as low and is SPL limited, and is it worth the savings...oh well just add extra piano gloss, NOW we're talking like a mass producer of premium speakers!

 

[kyle_neuron]

Minidsp uses proportional Q filters while Hypex and most other uses Constant Q filters. Could this explain it?

Firstly congratulations @Rick Sykora @ctrl and anyone else involved. This is an excellent result for a DIY project by any standards. I look forward to the floor-standing version

In the ‘pro’ world, I’ve assessed many DSP units programmed with the same filter values via two-channel measurements. They all show a huge variation in output response, which means I keep an output trace from the ‘gold master’ DSP unit and use that as a reference for other DSP’s output measurements when configuring those.

Often, the filter’s frequency and Q values aren’t particularly close to the original numbers, for the same output response.

I would expect much the same in the home or hifi world. A measurement of the speaker terminals on the Hypex amp that the designers are using would be useful

 

[abdo123]

So now here comes the fun part - what if you stripped down the "exotic" driver materials to the cheapest available leaving only the barest system essentials: active DSP, box dimensions and shape. How close does this version get to the original?

the directivity would be messier, and the maximum output would be lower. Getting a flat listening window would be trivial once you have an NFS and you're making an active design.

 

[Spocko]

I love the simplicity and security of those SpeakOn terminals!

 

[mdsimon2]

So what needs to be done to get the DSP / amplifier off the top of the enclosure for NFS measurements?

I thought there was some discussion on another thread that this might be possible with minimal wiring modification to the NFS. Although we all hope that the resonances are due the loose gear on top if they were inherent to the enclosure that would be good to know (and another project to tackle!).

Michael

 

[abdo123]

So what needs to be done to get the DSP / amplifier off the top of the enclosure for NFS measurements?

Adopting the Hypex Fusion Amplifiers moving forward will simplify testing and measurements but will require more extensive cabinet building and design.

 

[respice finem]

Rome wasn't built in a day

 

[Rick Sykora]

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.

Sorry as it may seem I am singling you out, but too often I see this same mistake being made on the forum overall...

While I appreciate what Genelec and others have accomplished, I think it is important to compare speakers that are intended for the same application space. A Genelec 8040 might be a well-designed nearfield monitor, but Directiva r1 was designed for use in far-field applications. Far-field (hifi) design puts a much greater demand on the speaker to be able supply more and lower bass (without a subwoofer) than the 8040 is able to deliver.

This would be no different than comparing the Genelec 8040 to a JBL Pro speaker. Nobody should expect a nearfield studio monitor to do duty as a high sensitivity sound reinforcement speaker (or vice versa). They are both speakers, but they are made for different applications. There is not much point in discussing value as the speakers are meant for different purposes.

 

[Dogen]

I’d like to see what can be done to a low price point - maybe $300 in materials for a $1000-1200 commercial design. That would be much more complicated, and it’s not my time being spent

 

[GWolfman]

Interesting results. Nice work & collab.

Looking forward to future projects!

 

[digitalfrost]

A quick note on a key implied requirement (of my own). The speaker would be targeted to be able to be used for music listening at 3-4 meters in a medium size room (~50 cubic meters) and produce solid bass down to 40 Hz (even away from walls). So, this speaker is designed to be used a far-field monitor.

What would you change for a near-field setup?

 

[ROOSKIE]

So what needs to be done to get the DSP / amplifier off the top of the enclosure for NFS measurements?

I thought there was some discussion on another thread that this might be possible with minimal wiring modification to the NFS. Although we all hope that the resonances are due the loose gear on top if they were inherent to the enclosure that would be good to know (and another project to tackle!).

Michael

Why not just take them without the dsp and amp, using only the woofer connected to the normal rig?
On take them in REW with them sitting off the speaker? No need for the Klipple for a quick HD test to confirm outside influence.

 

[ROOSKIE]

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 wonder if the passive radiator is a bit small for the displacement capability of the woofer at maximum volumes.
If so then it could be the source of some noise.
It appears to be a close call, has anyone confirmed it can hang at maximum?

 

[Robbo99999]

Cor, that's a lovely speaker! Reminds me a little of my JBL 308p after Anechoic EQ, without the distortion though!

 

[respice finem]

...Directiva r1 was designed for use in far-field applications. Far-field (hifi) design puts a much greater demand on the speaker to be able supply more and lower bass (without a subwoofer) than the 8040 is able to deliver...

I wasn't aware of this. Can it really work, esp. distortion-wise, for this size membrane surface?
My half-educated guess is, THD in bass would likely go through the roof(?)

 

[voodooless]

I wonder if the passive radiator is a bit small for the displacement capability of the woofer at maximum volumes.
If so then it could be the source of some noise.
It appears to be a close call, has anyone confirmed it can hang at maximum?

I did a quick sim, and it looks like it's just about an okay fit. MaxSPL is limited though, so I can imagine that Amir heard some ominous noises when playing loud. Here is the MaxSPL curve with the PR, I uses about 20 liters here, so real numbers might be a bit different:

So @abdo123, this is not a no-compromise system. Nothing ever is. Now the Purify has some mm left until Xlim, but distortion will rise quickly. the PR however is exhausted at this point. This graph BTW is quite in line with the distortion measurements @ 96 dB. below 100 Hz it shoots up like crazy.

From where I stand, this would be hardly acceptable for far-field listening if you like a bit of dynamics. Will surely need a sub to strengthen the low end.

Edit: so looks like it's not as "bad" as it looks. For some reason I got fed the wrong datasheet and I used the one with the 6 mm Xmax. The story is a bit different now:

Blue line is the correct Purify version. It gives about 3 dB more output below 30 Hz. Still output is a bit limited below 80 Hz.

 

[617]

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?

Im not saying it's not a successful design, I guess what I'm trying to say is that I'm disappointed Amir didn't have any particular reaction to the bass. I'm aware of what the purefi woofer can do on paper, but I wanted to read some personal impressions.

We live in a golden era of small woofers it seems, between this, the anarchy, even the woofers in the JBL 7 series monitors.

I guess what I want to hear is 'this tiny speaker is as loud and dynamic as my 8" floor stander".

 

[Remlab]

This could be a good alternative to the Seas tweeter. Goes down to 1.5khz with zero problems(Even lower with an 8th order) and will most likely fill the vertical directivity hole.

https://www.parts-express.com/pedocs/specs/264-1678--peerless-da32tx00-08-spec-sheet.pdf

Another, but very expensive..

BlieSMa T34A-4 | HiFiCompass

hificompass.com