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Directiva r2 project: market requirements gathering

JRS

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I keep staring at these dedicated tweeter/midrange coaxials from SEAS for that. They have a ton of woofers, but I'm a sucker for matching and their 7" reed woofers look really nice.
A good value according to Zaph Audio. In case you're unaware of these msmt's, John put together the SR 71 design many moons ago. Were you thinking of a 2.5 design with the straight 7" supporting the low end and then getting out of the way as you near the XO point?
 

alex-z

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Unless KEF markets the driver for DIY use, am hesitant to use something that has limited availability and/or lifecycle issues. If we put major effort into a reusable design, do not want to get to the end and find out the driver is unobtainable. That said, have at it as a side project!

Have looked at the Dayton and agree that it is attractive and so is the RS225. Both @ctrl and I have RS225s already. As you mentioned, it is kind of big, so will keep on the list for now. Thanks!

My thought was that even if KEF does stop Q150 production, it will likely only be for a higher quality replacement. They have been refining the current Uni-Q design since about 2007. Even the LS50 Meta woofer is physically the same size I think?

Another reason the RSS265HF-8 is a good candidate is the 1.5ft knockdown cabinet from Denovo fitting it. Then take the .56ft knockdown from the R1 and place it on top for the mid/tweeter. Think Paul Carmody Tarkus, but not quite as pretty. I assume the goal for Directiva R2 is still to have them be easily built by people who lack woodworking tools.
 

abdo123

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Hello Everyone! Unfortunately i don't have any of the expertise necessary to assist you in the design process.

but i want to be involved in the listening and measurin whenever you're set on a baffle and cabinet.

I would love for you guys to explore 3D printing to make it so ANYONE can print / order the design to be printed anywhere in the world.
 
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JRS

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While it might be more of a 'Directiva R1.5', a sealed version of R1 would be a nice small step of evolution.

It would allow some work on sealed bass without having to start from scratch with a new cabinet. It's kind of a principle of product design that small iterations lead to better results. By holding more things constant you can see the effects of the changes you _are_ making more easily.

From there you could go to a different woofer, a tower cabinet, a coax mid/high, etc. But just removing the PR from the R1 seems like the easiest first step.
Agree with the one step at a time approach, but wasn't a sealed enclosure rejected on acct of it's low Qt? I mean given the excursion, some bass EQ is definitely an option, just wondering.
 

headshake

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Another reason the RSS265HF-8 is a good candidate is the 1.5ft knockdown cabinet from Denovo fitting it.
The L26ROY also fits the large Denovo 10" sub box w/o any changes.

While I do think KEF drivers are nice, I don't trust the market to buy them. Have you looked at what you can get out of China on ebay? How do you know you aren't buying factory rejects or fake?
The tweeter in the SB16PFCR25-4 coax has good directivity matching in the 2500-4000Hz crossover region. Unfortunately it seems to fall apart even at 20 degrees off-axis if the datasheet is right.
Maybe the 5" then? It looks a bit better as far as the tweeter. It is a darn cheap part. I don't like how the datasheet stops at 20 degrees though.

On the opposite end, the Seas Excel C18EN002/A (E0060) looks nice. It is not cheap, but it has a waveguide mid, 2nd gen design, neo magnets, low distortion.. you have to ignore the on-axis since it is meant for off-axis listening.
 

D!sco

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A good value according to Zaph Audio. In case you're unaware of these msmt's, John put together the SR 71 design many moons ago. Were you thinking of a 2.5 design with the straight 7" supporting the low end and then getting out of the way as you near the XO point?
Yup, exactly. First order crossover around the 500hz point to reduce excursion on the coaxial driver and raise the overall SPL without causing distortion. The lobing on a midwoofer should be minimal like this, too. I could do a medium bookshelf or towers, like the KEF R-series. SB Acoustics is very attractive for this project, also. Their woofers/coax are much less expensive and have very high excursion and a low Fs. I've been playing with the idea of full range with coax and some small sub drivers, but it's proven finicky.

Funny about the crossover point for the SR71 is it's exactly where they recommend the coaxial crossover, higher order but with less notch filtering. It would probably be really easy to stack these up for SPL purposes, or even get them running in a CBT or line-array. I can dream, at least.
 
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Rick Sykora

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Yup, exactly. First order crossover around the 500hz point to reduce excursion on the coaxial driver and raise the overall SPL without causing distortion. The lobing on a midwoofer should be minimal like this, too. I could do a medium bookshelf or towers, like the KEF R-series. SB Acoustics is very attractive for this project, also. Their woofers/coax are much less expensive and have very high excursion and a low Fs. I've been playing with the idea of full range with coax and some small sub drivers, but it's proven finicky.

Funny about the crossover point for the SR71 is it's exactly where they recommend the coaxial crossover, higher order but with less notch filtering. It would probably be really easy to stack these up for SPL purposes, or even get them running in a CBT or line-array. I can dream, at least.

Yes, Zaph’s ZA5s are my second, third and fourth kits. I have studied his work extensively.

If you are referring to the ER18, it is a venerable woofer. Aged but worthy of serious consideration. Will keep it in mind. Thanks!
 

mcdn

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Rick Sykora

Rick Sykora

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My thought was that even if KEF does stop Q150 production, it will likely only be for a higher quality replacement. They have been refining the current Uni-Q design since about 2007. Even the LS50 Meta woofer is physically the same size I think?

Another reason the RSS265HF-8 is a good candidate is the 1.5ft knockdown cabinet from Denovo fitting it. Then take the .56ft knockdown from the R1 and place it on top for the mid/tweeter. Think Paul Carmody Tarkus, but not quite as pretty. I assume the goal for Directiva R2 is still to have them be easily built by people who lack woodworking tools.

If we do not do the coaxial, like the premise of small monitors on top of a bass module. Do not recall Tarkus, but Bagby did something like this with the Adelphos. It would have the advantage of the monitors being small enough to ship to Amir without the bass module.
 

McFly

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Have looked at the Dayton and agree that it is attractive and so is the RS225. Both @ctrl and I have RS225s already. As you mentioned, it is kind of big, so will keep on the list for now. Thanks!

RS225 not suitable for sealed enclosures due to phase plug? i.e. it leaks?
 

D!sco

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The L26ROY also fits the large Denovo 10" sub box w/o any changes.

While I do think KEF drivers are nice, I don't trust the market to buy them. Have you looked at what you can get out of China on ebay? How do you know you aren't buying factory rejects or fake?

Maybe the 5" then? It looks a bit better as far as the tweeter. It is a darn cheap part. I don't like how the datasheet stops at 20 degrees though.

On the opposite end, the Seas Excel C18EN002/A (E0060) looks nice. It is not cheap, but it has a waveguide mid, 2nd gen design, neo magnets, low distortion.. you have to ignore the on-axis since it is meant for off-axis listening.
I love the C18EN002/A idea so much, but the King Roy already exists. It's a hypex powered coax/sub bookshelf that fits on a JBL LSR308 sized stand. I dream of it some nights, and that's why it costs $1800/speaker before labor. I just want something accessible. Maybe the answer is the Dayton Coax, in a line array no less. I really don't think so, but maybe it is! For $35, I'll go dipole if it measures up. Directiva R1 is expensive, and while I'm not opposed to quality, I'd like to build one of these someday, too.

Can't wait for the passive crossover R1 results, too.
 

617

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The success of the directiva hinged on the constraints chosen early in the project. Decide now, active vs passive and how big.

My suggestion. Copy the driver sizes of revel f206 or 208.

2x Sb17nbac-4 in series
1x sb15mfc or other mid
1x seas dxt

I've simulated this speaker and the bass would be excellent.

Or for a big speaker:

2x sb23nbac4 in series
1x sb17mfc or something else
Dxt

Or if you want to get drivers from parts express:
2x rs225-4 in series
1x rs150p or something else
Wavecor horn loaded tweeter or maybe peerless dx34 corundum dome. Or DXT.

I've been working off and on with this idea for a while and I think the rs225, sb17 and sb23 are your best passive tower woofer values.

Another good option is a rs270p sealed, for a small classic shaped speaker like a JBL century.

If you want to do wide dispersion there is a very intriguing new satori dome tweeter.

I would recommend avoiding coaxial, the only options available to diyers are pretty mediocre compared to what you can get with a cheap mid and tweeter.
 

mcdn

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R1 feels like a proof of concept, showing that "non professionals" can use well tested design principles and free tools to create an exceptionally well performing speaker. In a way it didn't really matter what R1's format was. What mattered was that it worked, scored well and sounded good. Its only real "customer" was Amir.

Who is the customer for the next speaker? It could be people who want a simpler build (i.e. without the PR). It could be people who want a cheaper build (i.e. without the Purifi). There are others who want a passive tower, or a coax design. There will be lots of calls for all sorts of things to be created, but I feel the important thing is for there to be more customers for the next iteration than for R1.

That said, I would argue for Rnext to stick with an active DSP approach, regardless of the form factor. Room correction is needed for any speaker, and the commercial market has passive speakers to cover all tastes. Directiva can fill a different niche.
 

JRS

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Yup, exactly. First order crossover around the 500hz point to reduce excursion on the coaxial driver and raise the overall SPL without causing distortion. The lobing on a midwoofer should be minimal like this, too. I could do a medium bookshelf or towers, like the KEF R-series. SB Acoustics is very attractive for this project, also. Their woofers/coax are much less expensive and have very high excursion and a low Fs. I've been playing with the idea of full range with coax and some small sub drivers, but it's proven finicky.

Funny about the crossover point for the SR71 is it's exactly where they recommend the coaxial crossover, higher order but with less notch filtering. It would probably be really easy to stack these up for SPL purposes, or even get them running in a CBT or line-array. I can dream, at least.
SB makes some killer, sanely priced drivers. Not a lot of first hand experience except for building a J. Bagby design using Sartori 7" midbass + ring tweeter. Very, very nice using either passive XO or my digital ones using brick wall slopes. Both Jeff and Troel among many others have make very popular designs using them as I am sure you're aware. Sounds like a very interesting project. I am sorely tempted to try something similar with my monitors as I'm migrating platforms from 6 ch dig out to 8 and have the option finally--but I'm looking at a grand for the midbass units (Scandanavian sourced so high ouch factor) + new cabs. If you do spring, hope you'll post a build thread.
 

JRS

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mcdn

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If we do not do the coaxial, like the premise of small monitors on top of a bass module. Do not recall Tarkus, but Bagby did something like this with the Adelphos. It would have the advantage of the monitors being small enough to ship to Amir without the bass module.
A possible roadmap could be:
  • do a sealed version of R1 first - simplifies the bass alignment, reduces build effort, but presumably increases bass distortion and power requirements
  • next swap out the Purifi woofer for something lower cost - would presumably lower max output and increase distortion in low bass again, but also maybe not, that's the fun of inquiry!
  • then add a bass module, removing the low bass requirement from the 2-way monitor and removing the output and distortion limits
That's three individually easy steps, and people could also work on different crossover arrangements in parallel.
 
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Rick Sykora

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Ok, a little brainstorming post, so bear with me…

Not trying to be selfish, but as r1 was done partly for Amir, r2 is more for my own use. That said, just the initial thread here demonstrates there are like-minded members. So, my vision for r2 is a more extensible speaker than r1. I want to start with a base set of solid parts and be able to deploy them in multiple ways. A good example is what Krutke did with his ZA5, but updating the approach to take advantage of more current technology.

Given this, agree we still need to have an initial target or two. So, while still like the floorstander aesthetic, suggest it might also be a bookshelf as well. So, while am tempted to keep the Seas DXT from r1, the Purifi woofer price is not conducive to being used for scalability unfortunately. If you accept the premise of my proposed concept, the coaxial gets shelved too. Am still pretty sure there is not a better alternative to the minidsp 2x4 HD, so plan to keep it for now.

So, the r2 bookshelf should get back to my price target of $1000 per pair (with XO and without amps). The floorstander would initially be the bookshelf in a larger cabinet, but also have a higher output version with an additional woofer. More cabinet and another woofer might push the price closer to $1400 but just a guesstimate for now…

So, suggest r2 needs a woofer that is $150 or less. r1 suggests that we can get good directivity with a smaller woofer and avoid the complexity of a dedicated midrange, so thinking it needs to be a 6-7 inch driver. We have a few queued, but on the high end a Satori MW16 comes to mind, but one of the SB woofers would likely do too. Like the idea that we could have a drop-in upgrade.

Realize this is getting long, so going to toss it back to members to get your feedback.
 
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Rick Sykora

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A possible roadmap could be:
  • do a sealed version of R1 first - simplifies the bass alignment, reduces build effort, but presumably increases bass distortion and power requirements
  • next swap out the Purifi woofer for something lower cost - would presumably lower max output and increase distortion in low bass again, but also maybe not, that's the fun of inquiry!
  • then add a bass module, removing the low bass requirement from the 2-way monitor and removing the output and distortion limits
That's three individually easy steps, and people could also work on different crossover arrangements in parallel.

Yes, as you now know, was contemplating along the same lines…

While I like the bass module premise, it strikes me as aesthetically challenged. Also, is almost a subwoofer too, but not quite. If enough others feel otherwise, may reconsider. It is not the first time I have pondered it and always seems to come up shy for me in the end. :)
 

Colonel7

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Yes, as you now know, was contemplating along the same lines…

While I like the bass module premise, it strikes me as aesthetically challenged. Also, is almost a subwoofer too, but not quite. If enough others feel otherwise, may reconsider. It is not the first time I have pondered it and always seems to come up shy for me in the end. :)
I don't feel strongly on this but Jeff Bagby wrote a white paper for his bass module which is helpful for those contemplating it - and it's aesthetic limitations.
 

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mdsimon2

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RS225 not suitable for sealed enclosures due to phase plug? i.e. it leaks?

No issues using the Dayton reference series in sealed enclosures, there are many designs that do so.

I have not personally used RS225s but I am thinking about a project with them when they come back in stock. I have used RS180s in sealed enclosures and in box T/S parameters as measured by Dayton DATS match exactly what you would expect.

Michael
 
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