Real life example please as I can’t recall seeing such a design.
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Directiva r2 project: market requirements gathering
- Thread starter Rick Sykora
- Start date
there is no real life example (maybe the Tom Danley Synergy horn without the horn?) I'm just curious if this is a good way to go to have multiple woofers in a baffle without having it be a floor stander.
I understand that the industry shifted away from having wide baffles for a reason that i don't remember right now, but that was in the 80s, we have technology now that they didn't have access to back then.
Sb23 aluminum cones are 127 dollars. Dayton RS225 are 74 dollars.
So in total you're looking at 300 to 500 dollars for four of them. The purifi is 740 for a two.
My point is that in terms of value, 2x8 is hard to beat. However, if you can ccept slightly less output, the sb17 aluminum drivers are very good as well.
So in total you're looking at 300 to 500 dollars for four of them. The purifi is 740 for a two.
My point is that in terms of value, 2x8 is hard to beat. However, if you can ccept slightly less output, the sb17 aluminum drivers are very good as well.
Unless you use a very wide baffle no speaker will have much directivity below 1000Hz. The wavelength at that frequency is longer than the baffle width hence it doesn’t block the driver. Speaker is in a 4Pi space.
Are you are suggesting two D’Appolito layouts where one set rotated 90 degrees?
I have not simulated such a design but I expect the low frequency units will create phasing errors. If you plan the outer units to be cut off below 1000 Hz then placement of the drivers wouldn’t matter much. All you will achieve a wide and chubby speaker, which is ergonomically not suitable for domestic rooms.
yes exactly, something like this ceiling speaker i found in the middle of nowhere. Ofcourse there would only be one high frequency driver in the center.
I believe that this is what Tekton tries to do. I've simulated this idea a lot. The responses always become rather ragged.
Ideally you'd want more than four drivers surrounding the tweeter. Of course then you have a huge difference in output potential.
A mid and tweeter work far better.
Your example is a PA speaker where the sound level is the main criteria. It was a wishful thinking design to boot. Please don’t see this the wrong way as arrogance but you need to study speaker design before making design suggestions for Hi-Fi speakers. There are a myriad of physical limitations we need to negotiate. We are all happy to help and guide but as this a speaker design thread a basic understanding of the job will be beneficial to all.yes exactly, something like this ceiling speaker i found in the middle of nowhere. Ofcourse there would only be one high frequency driver in the center.
Well there is not really a book or a university course one could follow on speaker design
I would love to learn more about this, but i haven't been able to find good sources.There are lots of books for various starting levels. Some better than others but for a beginner all should help.Well there is not really a book or a university course one could follow on speaker design
any of these in particular you recommend over the others?
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DNA Sequence, if you don't mind a slight clocking of the array. I can't recall seeing a polar map, but it's been years since I read the patent.
Also see Follgott's "pseudo-coax" actively phased array. An important lesson is that dimensions matter, even for active pattern control.
It's something you can make sort of work but the off axis is super chaotic.
I think that at a very small scale you can achieve interesting results. The Hanover hardcore German dude did some small kids surrounding a ribbon I think? And Sony used to do these tiny tweeter/super tweeter arrays. However for mids you are better off just using a big woofer.
I think that at a very small scale you can achieve interesting results. The Hanover hardcore German dude did some small kids surrounding a ribbon I think? And Sony used to do these tiny tweeter/super tweeter arrays. However for mids you are better off just using a big woofer.
I’m afraid I haven’t read any of them. My education was a long time ago at university level first then through scientific and engineering papers.
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JRS
Major Contributor
I'm wondering whether the choice of 1, 2, 3 could be left to the builder's discretion. Just provide some guidelines as to desired f3, max output, approximate effciency and the height for providing a stand for the top box. Certainly there is nothing wrong with having recommended drivers and a cabinet, but I'm thinking bass is bass, provided the cabinet is sturdy and the drivers capable. This would provide some freedom to follow heart, budget, required WAF or whatever.
Well what do we want over Directiva R1?
A: An upgrade path for R1 builders.
S: Louder and deeper
M: 3dB or higher sensitivity; F3/F10 lower by 10Hz
A: Doesn't need new NFS (using near field measurements for woofers are entirely appropriate; and accurate up to f(Hz) = 4311/Diameter of emissive cone area (inches)
R: Select bass bin size and appropriate woofer, and then do new W/M crossover, some MT tweaks (remove BSC)
T: 2-3 months (Christmas or Q1 2022)
Option B: New speaker, based on all knowledge gained by designing R1
S- Lower cost, but equal performance
M- Same F3/F10; preference score, cost of drivers at least significant cost reduction (33%)
A- W+M+T <=$300USD; yes; lots of candidates
R: More difficult, will need completely new cabinet and baffle design and NFS measurements
T: 1 year (if it took 8 months to do a Directiva; a 2 way with a DSP crossover, it'll take 6-12 months to do the first 3 way)
A: An upgrade path for R1 builders.
S: Louder and deeper
M: 3dB or higher sensitivity; F3/F10 lower by 10Hz
A: Doesn't need new NFS (using near field measurements for woofers are entirely appropriate; and accurate up to f(Hz) = 4311/Diameter of emissive cone area (inches)
R: Select bass bin size and appropriate woofer, and then do new W/M crossover, some MT tweaks (remove BSC)
T: 2-3 months (Christmas or Q1 2022)
Option B: New speaker, based on all knowledge gained by designing R1
S- Lower cost, but equal performance
M- Same F3/F10; preference score, cost of drivers at least significant cost reduction (33%)
A- W+M+T <=$300USD; yes; lots of candidates
R: More difficult, will need completely new cabinet and baffle design and NFS measurements
T: 1 year (if it took 8 months to do a Directiva; a 2 way with a DSP crossover, it'll take 6-12 months to do the first 3 way)
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JRS
Major Contributor
Good for trying to clarify. I thought we were making bass bins that could be used with either the R1 or R2 and that the R2 was even more ambitious in terms of directivity. And that knowing there was augmented bass available, we could use a less expensive driver and direct the savings into a cardioid implementation. Seems a bit of spaghetti thread at the moment.
I’m must had missed the good coaxial target.
I know of no good coaxial driver available for DIY market that are as good as the KEF range.
But still; a co-axial is just a co-incident mid and tweeter. Still needs a crossover. And that’s the secret sauce that needs optimisation to all speakers (see Directiva vs SPK5)
So it’ll be interesting to see what comes of this.
I know of no good coaxial driver available for DIY market that are as good as the KEF range.
But still; a co-axial is just a co-incident mid and tweeter. Still needs a crossover. And that’s the secret sauce that needs optimisation to all speakers (see Directiva vs SPK5)
So it’ll be interesting to see what comes of this.
The secret sauce is really good measurement technique. Making a crossover is pretty easy nowadays if you have the resolution of measurements the directiva team had from the NFS. I do not believe we will have access.to the NFS this time around.
A few thoughts on improving directivity in the bass before my employer claims my time for the day:
So eventually (maybe not as a first iteration) it would be awesome to see:
Specific: Extended directivity control down to low midbass, using an active woofer module
Measurable: Directivity controlled to +-100 degrees down to 150Hz instead of the current 400Hz, with an F3 of 40Hz just like R1 (stretch goal, move F3 to 35Hz)
Achievable: Seems well within the bounds of Rick and @ctrl's capabilities. No changes other than a cheaper mid woofer and removal of the PR needed to R1
Realistic: We have an existence proof in the W371A, knock down cabinets available from Parts Express
Timely: Probably not as a next evolution
In practical terms, if Rick wanted to go there, perhaps the next evolution only needs to be a sealed bass module using cheaper woofers all round to prove out the basic build?
- Drivers are not actually a huge part of the BOM unless using esoteric parts like the Purifi woofer
- Custom cabinets are really really hard and expensive
So eventually (maybe not as a first iteration) it would be awesome to see:
Specific: Extended directivity control down to low midbass, using an active woofer module
Measurable: Directivity controlled to +-100 degrees down to 150Hz instead of the current 400Hz, with an F3 of 40Hz just like R1 (stretch goal, move F3 to 35Hz)
Achievable: Seems well within the bounds of Rick and @ctrl's capabilities. No changes other than a cheaper mid woofer and removal of the PR needed to R1
Realistic: We have an existence proof in the W371A, knock down cabinets available from Parts Express
Timely: Probably not as a next evolution
In practical terms, if Rick wanted to go there, perhaps the next evolution only needs to be a sealed bass module using cheaper woofers all round to prove out the basic build?
