Budget Directiva Project

[Rick Sykora]

Ever since Directiva r1 specified the pricey Purifi woofer, there have been requests for a lower cost version. I have been shopping less expensive woofers and am prepping to evaluate them. The initial evaluation will continue with the Seas DXT tweeter but may consider others as it has become rather pricey as now too. Another potential cost reduction would be to drop the passive radiator, so this is likely as well. In line with a lower cost target, the initial crossover design will be passive but will consider a low-cost active option. More like r1, also plan to keep to a simple cabinet but will likely include a smaller sealed design (depending on woofer choice).

Am anticipating a fair amount of forum feedback and with r2 still in progress, planning one doing this project solo. In a later post, will share my woofer selections. They are all around 6.5 inches and, for cost and availability, may allow more than one choice if they fit the same cutout. Most of them are slightly larger than the r1 woofer.

I am hoping to make this a short project (less than a few months). Aside from measurements though, just found that will need to seek out other options for cabinets as the Denovos are no longer available. Am more in favor of precut baffles but am open. So, this may take a bit more time.

 

[hex168]

Looking forward to your results!

Just a thought: I do not know if people would like or dislike the appearance, but an upholstered box can let people get away with Home Depot (or equivalent) cuts and lots of glue. Jigsaw cuts for the drivers, surface mounted. A couple of inches of polyester batting or foam as padding, nice fabric and some staples, done. I think someone more skilled than I (not a high bar) could come up with something actually good-looking. Acoustic benefits, too.

 

[D!sco]

Would a budget directiva benefit from a budget subwoofer option?

 

[alex-z]

For the cabinets, I know places like solen.ca offer CNC machining. It is $100 CAD per hour + materials though, so probably $150 for a pair of bookshelf speakers.

As for the passive radiator, I think it worth keeping. A bass reflex design without having extraneous port resonances really sets Directiva apart. I know KEF has some fancy port designs using closed cell foam, but that means complicating the build process and potentially still not reaching the same performance level.

 

[Trdat]

I like the sealed idea, we save on the passive radiator and can add subs to the design. I get this is the budget version but I am also still up for a coaxial design with a couple woofers but don't want to hijack this thread, so back to reality.

The Denovos would have been a great option doesn't parts express have any other cabinets for sale?

Lets keep the tweeter, I don't think its should be a budget budget, the purifis are expensive and if we add a sub then the woofer doesn't need to perform at that level hence we can find a cheap option with decent quality and also not skimp on the tweeter or at least choose decent tweeter.

 

[DWPress]

I'm currently using a Dayton RS150P-4 6" for mid woofer duty and am quite pleased with my gated measurements for a budget woofer. Good down to 100Hz and doesn't start beaming (according to PE) until 2kHz.

 

[mcdn]

Looking at The original BOM, the expensive parts are the Purifi woofer. The MiniDSP, and the 4 channels of amplification required. And probably the machining of the cabinet unless the builder has the right tools and skills.

Saving cost by going passive is already well addressed in the directiva r1 Passive xo thread, so the job here would be to settle on a single recommended passive XO. Alternatively there are cheaper ways to go active, but now the builder has to build a case etc to house a DSP amp module, and program it, and it all soon doesn’t save money at all!

So the opportunities to save costs while sticking to the core design are really only:

• go passive - easy and proven
• change the woofer - easy, but needs work to mate with appropriate PR
• reduce cost of cabinet - requires some thought. Open source CAD files that can be given with confidence to your local place? Group buys?

Maybe the other alternative is to stick with most of the original Directiva design goals but at a radically lower price point, and come up with something totally new?

 

[mcdn]

Actually open source CAD files would be great. My local community shed (an Aussie thing - maker space for woodworking etc) has a CNC router that takes vcarve files I think. If I had the files prepared I could knock out cabinets for free for local use.

 

[617]

I assume this will be a cardioid? If I remember correctly, the original directiva was not that hard to make a passive filter for.

Looking forward to seeing how you approach this, Rick.

 

[Trdat]

Looking at The original BOM, the expensive parts are the Purifi woofer. The MiniDSP, and the 4 channels of amplification required. And probably the machining of the cabinet unless the builder has the right tools and skills.

Saving cost by going passive is already well addressed in the directiva r1 Passive xo thread, so the job here would be to settle on a single recommended passive XO. Alternatively there are cheaper ways to go active, but now the builder has to build a case etc to house a DSP amp module, and program it, and it all soon doesn’t save money at all!

So the opportunities to save costs while sticking to the core design are really only:

• go passive - easy and proven
• change the woofer - easy, but needs work to mate with appropriate PR
• reduce cost of cabinet - requires some thought. Open source CAD files that can be given with confidence to your local place? Group buys?

Maybe the other alternative is to stick with most of the original Directiva design goals but at a radically lower price point, and come up with something totally new?

Hear Hear!

 

[Rick Sykora]

Would a budget directiva benefit from a budget subwoofer option?

Plenty of those already imo.

 

[Rick Sykora]

I'm currently using a Dayton RS150P-4 6" for mid woofer duty and am quite pleased with my gated measurements for a budget woofer. Good down to 100Hz and doesn't start beaming (according to PE) until 2kHz.

Might have a RS180 around to try but have some other options so will see.

 

[Rick Sykora]

I assume this will be a cardioid? If I remember correctly, the original directiva was not that hard to make a passive filter for.

No, but will leave as a potential option for a later round. To do the quickest turn, the simplest approach will be just replacing the Purifi woofer and possibly the passive radiator. A good, vented design should be possible too but understand some reluctance in that regard. I tested a supposed ideal r1 design with the Purifi PRs and it had some ugly resonances too. A passive radiator is not a panacea.

 

[MarnixM]

Ever since Directiva r1 specified the pricey Purifi woofer, there have been requests for a lower cost version. I have been shopping less expensive woofers and am prepping to evaluate them. The initial evaluation will continue with the Seas DXT tweeter but may consider others as it has become rather pricey as now too. Another potential cost reduction would be to drop the passive radiator, so this is likely as well. In line with a lower cost target, the initial crossover design will be passive but will consider a low-cost active option. More like r1, also plan to keep to a simple cabinet but will likely include a smaller sealed design (depending on woofer choice).

Am anticipating a fair amount of feedback and with r2 in progress, am doing this project solo. In a later post, will share my woofer selections. They are all around 6.5 inches and, for cost and availability, may allow more than one choice if they fit the same cutout. Most of them are slightly larger than the r1 woofer.

I am hoping to make this a short project (less than a few months). Aside from measurements though, just found that will need to seek out other options for cabinets as the Denovos are no longer available. Am more in favor of precut baffles but am open. So, this may take a bit more time.

Based on the TS-parameters (in particular the large X-max (10mm) of the Purifi) the Tang Band W6-1721 Bass-midwoofer seems to be an option, Nice smooth frequency curve with natural roll-off in the lower region. But it is only 50Watt RMS. No experience with it. The price in the Netherlands is about €130,-

 

[Deleted member 48726]

So.. The budget directiva is sporting
-Different drivers
-Different crossover
-Different design
-Different cabinet

--> not a directiva but a completely different speaker?!

 

[Rick Sykora]

So.. The budget directiva is sporting
-Different drivers
-Different crossover
-Different design
-Different cabinet

This is not what I stated in the opening post, so did you not read?

--> not a directiva but a completely different speaker?!

If you are asking, the Directiva project is not bound by the r1 speaker design. Although it would a shame not to build on the design experience from r1. We did with r2 as it kept the Seas DXT tweeter, The intent of the project is to create useful speakers. Yes, the project name was picked to emphasize directivity as a design goal. I see consistent directivity as just one aspect of the design approach though.

 

[Deleted member 48726]

... I have been shopping less expensive woofers ... will continue with the Seas DXT tweeter but may consider others ... drop the passive radiator, ... the initial crossover design will be passive ... but will likely include a smaller sealed design (depending on woofer choice).

Is this not a completely different speaker though?

 

[Rick Sykora]

Is this not a completely different speaker though?

That is part of the project to determine. Could just be r1 with a different woofer but am open to a wider range of options. Directiva is a project and not a single speaker. Amir did not differentiate this in his review so can see there may be some confusion. Note all the other threads here refer to the Directiva project and specific instances by a release designation. Amir reviewed Directiva r1.

 

[D!sco]

The Purifi woofer is going to be a tough act to follow. Have all the woofer options come through yet? I keep thinking about the Zaph 5.X series with increasingly more drivers and the scalability of budget systems whenever the idea of following a top of the line woofer shows up. That or increasing the woofer diameter. Eight 6" SB Acoustics drivers still cost less than a pair of Purifi's. So do two 10" pro midwoofers. It's all about the constraints. I've always adored projects that scale, so taking the DXT from one level of Directiva to another could be a nice mark of progression.

I can only think of the Dayton RS series or SB Acoustics midwoofers as a value alternative. Curious what this project lands on, anyways.

Last thought is the DXT could ultimately be a budgetary constraint. The price keeps going up, and there are plenty of alternatives. It may not be conducive to a quick project, but a horn-loaded compression driver in Directiva could be an interesting choice, and less expensive than a DXT in total. There is also the Visaton 1" compatible waveguide for $20 that could open the possibility for more tweeters in the future with better controlled dispersion.

 

[morpheusX]

Could this be an interesting alternative? It seems interesting from an innovation perspective:

Wom165_vMS | .Kartesian

www.kartesian-acoustic.com

It can be obtained in canada for $178: https://www.solen.ca/en/products/wom165_vms-8