Any interest in an ASR community speaker project?

[617]

These types of models where you enter in driver size and mounting and baffle dimensions model two things, diffraction and driver radiation off axis (dispersion). The error you mentioned is mostly due to the model of driver dispersion, not the diffraction. It assumes the driver radiation is the solution to the wave equation for a rigid pistonic disc. A real speaker cone enters into break up and emits like a smaller cone at higher frequencies, broadening radiation there. There are no physical parameters specified for speaker drivers that lets anyone model this break up except the driver's designers that have access to the FEM model.

To have a hope of an off axis simulation useful for DIY design, the actual driver radiation on an IEC baffle needs to be used (available from the manufacturer or retailer), the IEC baffle's diffraction "backed out" using the tool's diffraction modeler, and then the diffraction of it mounted in the target box modeled and added back in. This has to be repeated at every observation/measurement location. I wrote this up here: http://audio.claub.net/software.html -> http://audio.claub.net/software/DaveDalFarra/Simple Loudspeaker Design ver2.pdf I wrote this up quickly for a DIY meet and Charlie and Jeff then went one better and later created their splice tool.

What I'm curious about is the second part, how well Vituix Cad models diffraction. It doesn't need to get this "wrong" by much to create audibly misleading results because the error will exist over a wide frequency range, so even small dB errors will be noticeable. Here's how the other tools fared compared with anechoic measurements. The Edge vs Paul's BDS vs Jeff Bagby's DBS (based off Paul's BDS so no surprise those two are close):

View attachment 68871

That's really great data there. Ultimately, with this speaker at least, the diffraction simulation is just a way to get an idea of what diffraction will look like. Naturally, full polar measurements at 10 degrees will be made, which will show diffraction effects pretty clearly.

The reason I'm going to the trouble of making a nice, accurate, tall platform is that I realize that quality of measurement is now the 'hard part' of speaker design. If you have really good data you can design a crossover with all the graphs in the cea 2034 right under your nose.

 

[dwkdnvr]

Now, onto some news. SIY has provided measurements of the Dayton amp, and the results are not that good. Actually, for the price I think this is still an amazing product, but I'm not sure I'd use it in a speaker with the level of performance we are attempting.

See the following AP captures:

View attachment 68847View attachment 68848


The power output is not that good; the supplied power supply only puts out 100W, with which we are powering 200W of amplifier boards. This might be rectified with a bigger power supply.

Distortion performance is not impressive. SINAD at 5W appears to be 48-58 db, which is pretty terrible for a hifi amp. Distortion seems to be more of a factor than noise.

When I get the amps I will listen to them myself and make a determination of their usability, but even if I decide they sound great, they severely limit the appeal of the project to audiophiles, perhaps for good reason. Who knows, maybe the amps in the JBL 708 are just as bad! Probably not.

So, this leaves us with a decision. Since the existence of these DSP amps was the inspiration for the 3 way design, we have to revisit some of our earlier project assumptions and choose a path forward.

[options deleted for space]

Anyway, please provide your thoughts moving forward. The most important decision is whether to make an active 3 way (expensive), a hybrid 3 way (somewhat cheaper but requires soldering), an active two way (relatively easy to build but requires a big WG) or whatever other option.

That's a bit disappointing, but big thanks to SIY for doing the measurements - better to have the info up front than spend time building a system around the amps.

Option 1 would require 1 MiniDSP unit per channel, or else moving up to the 2x8 or 4x10, which definitely raises the price target. 6 channels of amp is a bit of a barrier as well.

Option 2 would probably have the broadest appeal, but is more of a constraint. I'm actually a fan of the hybrid passive/active 3-way, but it definitely is a bit of a compromise compared to the initial direction. the MiniDSP 2x4HD plus your suggestion of 50ASX2 / 200asc/200AC would run about $500 for electronics I think, which isn't terrible but is definitely noticeably higher than the original target. Plus any 2 stereo amps that someone has on hand could be subbed in if desired.

Option 3. This is somewhat well-trodden ground recently. Jeff Bagby has the Helios which is basically the price-no-object version of this idea (Satori WO24P + Satori BE Waveguide tweeter. ~$650 per side in driver cost). Javad S is apparently working on a budget version based around the SB23NBAC, SB29 tweeter and custom waveguide. Then there's the Grimm LS1 idea using an 8" woofer and the DXT tweeter (I think the RS225 could probably pull this off pretty well, although not as well as the Satori WO24P at 3x the price). I think the big barrier here is designing a good tweeter/waveguide combo if we don't want to just go with a proven design. At first glance, off-the-shelf options would be the DXT, pricey Satori, or Augerpro has an 8" for the Dayton RST https://www.somasonus.net/dayton-rst28 which at first glance would probably work with the RS225, but once again has the problem of making printed or machined versions available. Or, go off the board and use the 18sound XT1086 and NSD1095N - $300/side for the tweeters, but remarkable measurements.

The main 'problem' with Option 3 is that it has shifted from being a fairly wide dispersion design to a narrower dispersion design. Not really a problem, but I thought that aiming for a wider design was part of the original motivation.

I'm torn on what I'd vote for. The hybrid 3-way is the closest to the original vision of the project, and the 2x4HD is proven if not exactly state-of-the-art at this point. However, the 8" 2-way is a bit different and having looked into the Grimm LS1 the concept intrigues me (even if this effort wouldn't go for the wide-baffle approach). Either the DXT or RST28+ WG would keep the budget in line, and might offer an excuse to pick up the 18Sound combo for comparison purposes.

 

[dwkdnvr]

In other news; I tried doing some measurements outside last weekend and it was just a mess. My measurement set up works but it lacks precision and is a major PITA to use. Since @hardisj pointed out the existince of these 'tic' stepper controllers, I have decided to revisit the idea of a computer controlled measurement platform. At the most basic implementation, I should pretty easily be able to control the tic using either its windows gui, or a series of windows shortcuts which can be assigned to move the stepper certain distances, but I am also trying to get a program working which allows ARTA to do measurements fully automated. My friend who knows python is currently working on this.

I spent some time looking into this very idea last week. Honestly, I think the easiest approach is just grab a cheap GRBL or even 3d Printer arduino shield and use that to drive the Nema 17 stepper. You have to do the calibration from X distance to degrees, but it leverages off-the-shelf stuff for the most part. Integrating with ARTA would just mean cribbing some code from one of the many g-code senders out there.

 

[617]

That's a bit disappointing, but big thanks to SIY for doing the measurements - better to have the info up front than spend time building a system around the amps.

Option 1 would require 1 MiniDSP unit per channel, or else moving up to the 2x8 or 4x10, which definitely raises the price target. 6 channels of amp is a bit of a barrier as well.

Option 2 would probably have the broadest appeal, but is more of a constraint. I'm actually a fan of the hybrid passive/active 3-way, but it definitely is a bit of a compromise compared to the initial direction. the MiniDSP 2x4HD plus your suggestion of 50ASX2 / 200asc/200AC would run about $500 for electronics I think, which isn't terrible but is definitely noticeably higher than the original target. Plus any 2 stereo amps that someone has on hand could be subbed in if desired.

Option 3. This is somewhat well-trodden ground recently. Jeff Bagby has the Helios which is basically the price-no-object version of this idea (Satori WO24P + Satori BE Waveguide tweeter. ~$650 per side in driver cost). Javad S is apparently working on a budget version based around the SB23NBAC, SB29 tweeter and custom waveguide. Then there's the Grimm LS1 idea using an 8" woofer and the DXT tweeter (I think the RS225 could probably pull this off pretty well, although not as well as the Satori WO24P at 3x the price). I think the big barrier here is designing a good tweeter/waveguide combo if we don't want to just go with a proven design. At first glance, off-the-shelf options would be the DXT, pricey Satori, or Augerpro has an 8" for the Dayton RST https://www.somasonus.net/dayton-rst28 which at first glance would probably work with the RS225, but once again has the problem of making printed or machined versions available. Or, go off the board and use the 18sound XT1086 and NSD1095N - $300/side for the tweeters, but remarkable measurements.

The main 'problem' with Option 3 is that it has shifted from being a fairly wide dispersion design to a narrower dispersion design. Not really a problem, but I thought that aiming for a wider design was part of the original motivation.

I'm torn on what I'd vote for. The hybrid 3-way is the closest to the original vision of the project, and the 2x4HD is proven if not exactly state-of-the-art at this point. However, the 8" 2-way is a bit different and having looked into the Grimm LS1 the concept intrigues me (even if this effort wouldn't go for the wide-baffle approach). Either the DXT or RST28+ WG would keep the budget in line, and might offer an excuse to pick up the 18Sound combo for comparison purposes.

Thanks for your input. For me the main issue is whether we go ahead with amp modules in the speaker or outboard. I think if the amp modules are in the speaker it only really makes sense to do the icepower plate amp. Getting 3 channels of amplification into the speaker and wiring it all up is needlessly complicated. On the other hand, if outboard amplification is used, the construction of the speaker becomes pretty easy - all it contains is one tiny, simple mid tweeter crossover network and a speakon connector for connection to whatever amps you have on hand. If they have different gains, you can easily attenuate the high or low outputs using the minidsp software and a sound meter - or just going by ear.

As far as hybrid 3 way vs active two way, they both make sense but I would favor the 3 way. First, the crossover for the mid/tweet could be very simple. Here's an example using some not-totally accurate data for simulation:

This is an arguably over-corrected crossover design which only uses a two components per channel plus some series resistance on the tweeter. I'm fairly confident with good measurement data a hybrid design can be just as good as a fully active design, unless serious high power is needed, or difficult to mate drivers are used. Here is the simulation:

If you look at the mid tweeter roll-offs you'd ideally want something a bit smoother, but if you look at the DI and sonogram you can see...that even with 5 minutes of effort and 5 crossover components I was able to get a pretty great response, completely flat on axis. Note that this simulation uses no waveguide, just a baffle mounted bc-25 tweeter. I don't know which baffle this corresponds to, I just opened a random Vcad file and brought in some impedance data to make things harder.

So, now that I've thought it through, I favor a hybrid 3 way with wide, smooth dispersion, which has a simple passive network, and offers the users to user either a minidsp plate amp, or their own amps and an outboard minidsp, or indeed any other dsp system of their choice.

I am a little biased against this approach, but I realize that I hate it because I did it years ago, with a huge poorly designed speaker that had an eight conductor goddamned speakon cable which then broke of into 8 rca jacks on the end. Just a nightmare. Most audio people can rustle up 4 channels of amplification, and the cost of a minidsp in a box is pretty moderate; if they decide the speaker is worth making with plate amps, they can do that.

Now, this lets us revisit the woofer choice, by the way. We were operating under the assumption that the KAB woofer amp, rated for 100W, would struggle to provide anything like that; which is probably correct, and so we sort of shunned woofers that required a big amp to get going. Seeing that an active outboard design offers the possibility of using whatever amps we want for the bass (iNukes, icepower) we can increase the overall output capabilities of the speaker by using a beefier 8" woofer, perhaps the SB23MFCL:

https://www.madisoundspeakerstore.c...cl45-4-8-polypropylene-cone-sub-woofer-4-ohm/

Response looks good to maybe 800hz, but you'd probably end up using it to 300hz LR4.

 

[617]

Regarding a two way active - this is a great idea for a speaker in theory. The soma sonus 8" waveguides for the rst28 and sb26 really show excellent measurements - I'd say the sb26 is slightly better on top, but I'd rather have the RST28's beef factor to cross lower. The problem is getting a woofer which is 8" and happy playing high up. The rs225p is an obvious choice, I'd say from this normalized off axis chart that it starts breaking up at around 3k:

But of course directivity rapidly decreases before then. I can do a simulation tomorrow comparing this data to the waveguide from soma sonus.

Regarding the viability of printing; for people with a sufficiently big 3d printer, printing the two waveguides will require a whole spool of material and over a day each of print time. This would cost quite a bit to have printed professionally, but I just got a printer and my time is free for my use...

This is with 40% infill.

I'm currently experimenting with fully 3d printed baffle designs:

Which use the 3d printer to basically made a thin shell of material which can then be filled with some cheap and heavy material such as resin mixed with sand. Printing a baffle conventionally leads to long print times.

This wouldn't be suited to a community focussed design but is fun to think about.

 

[TimW]

I like the 3-way design for its wider directivity compared to the 2-way. I also like limiting the number of amplification and DSP channels to 4 because it keeps plenty of options open. Very interested to see where this 3D printed baffle and hybrid 3-way crossover might go.

 

[617]

I like the 3-way design for its wider directivity compared to the 2-way. I also like limiting the number of amplification and DSP channels to 4 because it keeps plenty of options open. Very interested to see where this 3D printed baffle and hybrid 3-way crossover might go.

Yeah me too. You can get a 3d printer with a 500mm square bed for under 1000 dollars now, and I got a very high quality unit with a 300mm bed for 700...you can get a unit that's probably totally passable for like 200-300 dollars now. The material cost is not outrageous at around 22 dollars a kg of PLA, but the killer is time. Printing with fine layers and good surface finish takes forever, which isn't a problem if you're doing it for fun, but if you're ordering parts from an online printing service, everything gets really expensive.

I had ordered some little flanges to connect the rst28f to a waveguide. These parts are about 4" in diameter and maybe 4mm thick or less, and it was like $20 for both. I just ran an estimate and it would cost me less than a dollar in materials and only 3 hours of time.

 

[617]

Fun update: I'm learning Python to get code working to create an ARTA interface for a stepper motor. Learning python itself is actually easy, the hard part is getting a working installation of the modules you need to get this to work (pip, pyyaml, particular version of Python)

I can only get my installation to work in Python 3.7, but the .exe which I am generating should work on any windows system.

I don't have my tic and motor yet, but it should be here before the weekend. Right now I have successfully written code which takes arta's supplied arguments and converts them into the proper commands (home and go to position.)

If you want to learn Python for a command line program like this I would recommend the Thonny IDE, it allows you to install packages via a GUI, and it also has a little box at the top of the screen to enter in command line arguments for the script you're working on.

If this ends up working well I may learn how to make a simple windows GUI which allows you to just click on different positions, to let this interface work with REW people / Holm heathens / Clio elitists / Fuzz measure weirdos.

 

[somebodyelse]

I guess I'm spoiled with linux - python usually just works. Virtualenv is worth a look if you're going to be working on multiple projects that could have different dependencies - I think it's available on Windows too.

Do REW etc. have interfaces to allow automated measurement, or are you just making the rotation easy before manually running and naming another measurement run? In any case I'd be interested in making this work cross-platform, and with other ways of driving steppers.

 

[DeruDog]

Regarding a two way active - this is a great idea for a speaker in theory. The soma sonus 8" waveguides for the rst28 and sb26 really show excellent measurements - I'd say the sb26 is slightly better on top, but I'd rather have the RST28's beef factor to cross lower. The problem is getting a woofer which is 8" and happy playing high up. The rs225p is an obvious choice, I'd say from this normalized off axis chart that it starts breaking up at around 3k:
View attachment 68972
But of course directivity rapidly decreases before then. I can do a simulation tomorrow comparing this data to the waveguide from soma sonus.

Regarding the viability of printing; for people with a sufficiently big 3d printer, printing the two waveguides will require a whole spool of material and over a day each of print time. This would cost quite a bit to have printed professionally, but I just got a printer and my time is free for my use...

View attachment 68973
This is with 40% infill.

I'm currently experimenting with fully 3d printed baffle designs:
View attachment 68974
Which use the 3d printer to basically made a thin shell of material which can then be filled with some cheap and heavy material such as resin mixed with sand. Printing a baffle conventionally leads to long print times.

This wouldn't be suited to a community focussed design but is fun to think about.

I have a CNC router, and can make baffles like this out of MDF, if that would be useful for experimentation. That said, I think the idea of a "community speaker" would be one that could be made without a 3D printer or a CNC router. I think it would be best to make a design that can be made with MDF, a table saw, and a router.

I appreciate all of the experimentation and thought that is going in to these speakers. I look forward to seeing where this goes.

 

[dwkdnvr]

I guess I'm spoiled with linux - python usually just works. Virtualenv is worth a look if you're going to be working on multiple projects that could have different dependencies - I think it's available on Windows too.

Yes, virtualenv does work on windows

Do REW etc. have interfaces to allow automated measurement, or are you just making the rotation easy before manually running and naming another measurement run? In any case I'd be interested in making this work cross-platform, and with other ways of driving steppers.

He's setting up the automation for ARTA, which does handle this - sets up file naming templates, and walks through a series of measurements invoking a configurable command program/script between each step. I don't think REW or Holm support anything like this, so it would require spending money. This type of setup would still make things somewhat easier with REW, but there would be manual work to name the measurements/files.


as usual, many ways to approach this. My thought was to leverage the cheap off-the-shelf grbl or ramps setups. This utility https://www.npmjs.com/package/clinc/v/1.0.0 is a NodeJS package to allow command-line access to GRBL, so it's possible to just say 'clinc g0 x50' or similar to move to the designated X location. somewhere you'd have to map between rotation angle and X distance as grbl sees it, but that's easy enough. For 'manual' use rather than with ARTA, an incremental move would be more useful - I'd have to refresh my g-code to pin that down but it should be possible. Being grbl, you could also set up limit/home switches pretty easily.[/quote]

 

[dwkdnvr]

I have a CNC router, and can make baffles like this out of MDF, if that would be useful for experimentation. That said, I think the idea of a "community speaker" would be one that could be made without a 3D printer or a CNC router. I think it would be best to make a design that can be made with MDF, a table saw, and a router.

I appreciate all of the experimentation and thought that is going in to these speakers. I look forward to seeing where this goes.

Well, the problem is that if you've followed the discussion so far, the conclusion seems to be unavoidable: it's really not possible to create a speaker that is in keeping with the "ASR" philosophy without a waveguide on the tweeter. It's just really difficult to get smooth directivity matching without it. So, the options are
- use an off-the-shelf tweeter with waveguide
- machine/print an appropriate waveguide.

The list of off-the-shelf options is pretty limited, particularly in the budget range. Basically, the Seas DXT, the cheap Dayton ND28FW, and maybe the Wavecor. The Dayton RST28F and the naked Vifa XT25 mate very well with both the Visaton WG148 and Seos-8, but @617 has already done a design with the RST/Visaton and the results seem to be 'good, but not state of the art'. I do think an RST/Seos + RS225 might be an interesting direction, but you're back to the wide/narrow dispersion question and the consensus seems to be heading in the 'would prefer wide over narrow' direction.

I think there are probably enough of us around that can print and/or machine waveguides to make an approach using a custom unit viable. I mean, it's not like we expect hundreds of people to come out of the weeds and start to build these - if we end up with even 10 sets being built, I'd consider it a big success (but maybe other folks are more ambitious).

Like you, my intent is to machine the waveguide directly into the baffle rather than as a separate assembly. If that works, I'd probably be able to make a limited number of baffles available - CNC is rather quicker than printing, although shipping a set of baffles will be more expensive than printed waveguides.

 

[DDF]

That's really great data there. Ultimately, with this speaker at least, the diffraction simulation is just a way to get an idea of what diffraction will look like. Naturally, full polar measurements at 10 degrees will be made, which will show diffraction effects pretty clearly.

The reason I'm going to the trouble of making a nice, accurate, tall platform is that I realize that quality of measurement is now the 'hard part' of speaker design. If you have really good data you can design a crossover with all the graphs in the cea 2034 right under your nose.

I agree, with the popularization of the important design targets through internet info share over the years, the design problem has gotten easier. Data preparation is still critical (garbage in, ....). Long FFT windows are a luxury to achieve low cut off frequency and high resolution in the frequency domain, but there are some ways to reduce the drawbacks of using shorter windows:

1. Low frequency cut off: near field measurement plus a good diffraction modeler. This is why I always validate the accuracy of any diffraction modeller, IME its a crucial tool in the design process
2. Good measured frequency resolution suits two main purposes: catching resonances and getting accurate woofer/mid measures for a 3 way crossover.
   • Catching cabinet resonances can be mitigated by proper box design and construction. Commercial cabinets that have to care about shipping weight and construction and so cost cut corners that lead to resonances, all avoided with DIY. Catching driver or port resonances is achievable using closer field measurement that allow wider windows
   • for lower frequency range crossovers, near field + diffraction model techniques work well. Lots of tools out there, but another reason that a diffraction modeling tool is so critical and needs to be verified IME

 

[somebodyelse]

He's setting up the automation for ARTA, which does handle this - sets up file naming templates, and walks through a series of measurements invoking a configurable command program/script between each step. I don't think REW or Holm support anything like this, so it would require spending money. This type of setup would still make things somewhat easier with REW, but there would be manual work to name the measurements/files.

That's pretty much what I expected, but wasn't sure if the others had automation interfaces or not.

as usual, many ways to approach this. My thought was to leverage the cheap off-the-shelf grbl or ramps setups. This utility https://www.npmjs.com/package/clinc/v/1.0.0 is a NodeJS package to allow command-line access to GRBL, so it's possible to just say 'clinc g0 x50' or similar to move to the designated X location. somewhere you'd have to map between rotation angle and X distance as grbl sees it, but that's easy enough. For 'manual' use rather than with ARTA, an incremental move would be more useful - I'd have to refresh my g-code to pin that down but it should be possible. Being grbl, you could also set up limit/home switches pretty easily.

Indeed - I mentioned GRBL and Firmata in hardisj's thread. You're thinking of G91 to switch to relative coordinates, and $100=(X axis steps per mm), or degree if that's what we're using as units. It's trivial for those of us who know how, but I thought it would be useful to add to the gui with instructions for those that don't.

 

[617]

Fun update: I'm learning Python to get code working to create an ARTA interface for a stepper motor. Learning python itself is actually easy, the hard part is getting a working installation of the modules you need to get this to work (pip, pyyaml, particular version of Python)

View attachment 69335

I can only get my installation to work in Python 3.7, but the .exe which I am generating should work on any windows system.

I don't have my tic and motor yet, but it should be here before the weekend. Right now I have successfully written code which takes arta's supplied arguments and converts them into the proper commands (home and go to position.)

If you want to learn Python for a command line program like this I would recommend the Thonny IDE, it allows you to install packages via a GUI, and it also has a little box at the top of the screen to enter in command line arguments for the script you're working on.

If this ends up working well I may learn how to make a simple windows GUI which allows you to just click on different positions, to let this interface work with REW people / Holm heathens / Clio elitists / Fuzz measure weirdos.

 

[617]

I have a CNC router, and can make baffles like this out of MDF, if that would be useful for experimentation. That said, I think the idea of a "community speaker" would be one that could be made without a 3D printer or a CNC router. I think it would be best to make a design that can be made with MDF, a table saw, and a router.

I appreciate all of the experimentation and thought that is going in to these speakers. I look forward to seeing where this goes.

If you can ship me some test baffles when my measurement set up is more refined that would be great. I deliberately designed the 4" waveguide so it could easily be recessed by hand using a 1/4" bit and a rectangular template.

 

[617]

Well, the problem is that if you've followed the discussion so far, the conclusion seems to be unavoidable: it's really not possible to create a speaker that is in keeping with the "ASR" philosophy without a waveguide on the tweeter. It's just really difficult to get smooth directivity matching without it. So, the options are
- use an off-the-shelf tweeter with waveguide
- machine/print an appropriate waveguide.

The list of off-the-shelf options is pretty limited, particularly in the budget range. Basically, the Seas DXT, the cheap Dayton ND28FW, and maybe the Wavecor. The Dayton RST28F and the naked Vifa XT25 mate very well with both the Visaton WG148 and Seos-8, but @617 has already done a design with the RST/Visaton and the results seem to be 'good, but not state of the art'. I do think an RST/Seos + RS225 might be an interesting direction, but you're back to the wide/narrow dispersion question and the consensus seems to be heading in the 'would prefer wide over narrow' direction.

I think there are probably enough of us around that can print and/or machine waveguides to make an approach using a custom unit viable. I mean, it's not like we expect hundreds of people to come out of the weeds and start to build these - if we end up with even 10 sets being built, I'd consider it a big success (but maybe other folks are more ambitious).

Like you, my intent is to machine the waveguide directly into the baffle rather than as a separate assembly. If that works, I'd probably be able to make a limited number of baffles available - CNC is rather quicker than printing, although shipping a set of baffles will be more expensive than printed waveguides.

Custom print an 8" waveguide is something I wouldn't ask anyone to do. It would take a long time and cost a fortune. A 4" waveguide, on the other hand, is much more manageable, and could even fit in a resin type printer.

I can produce whichever geometry you want of course (cnc'd into baffle or 3d printed)

 

[dwkdnvr]

Well, the problem is that if you've followed the discussion so far, the conclusion seems to be unavoidable: it's really not possible to create a speaker that is in keeping with the "ASR" philosophy without a waveguide on the tweeter. It's just really difficult to get smooth directivity matching without it.

Well, having said that, this does look pretty darn good for a flat-baffle 3-way. Only out to 45 degrees, and you can see some directivity problems in the 1-2k range (quite possibly diffraction related), but pretty good.
http://techtalk.parts-express.com/f...6265-jeff-bagby-tribute?p=1444128#post1444128

Apparently one of these will be making it's way to Amir, so it'll be interesting to see it on the NFS

 

[617]

That's pretty much what I expected, but wasn't sure if the others had automation interfaces or not.

Indeed - I mentioned GRBL and Firmata in hardisj's thread. You're thinking of G91 to switch to relative coordinates, and $100=(X axis steps per mm), or degree if that's what we're using as units. It's trivial for those of us who know how, but I thought it would be useful to add to the gui with instructions for those that don't.

My choice of the tic interface rather than grbl is because it was easier for me to understand. The tic documentation is very good and simple for someone running windows, which seems to be the dominant platform for speaker designers. It controls one stepper, but that's all you need for this application.

The software I am making is called by ARTA directly but creating a version with a gui that has buttons for home and then 5/10/15.. degrees would not be hard. This would enable use with other measurement interfaces. It wouldn't be automated, but it would make measurements a lot easier.

One thing I need to figure out is how to take inputs from a configuration file in python (I have been using python for less than 30 hours). This will enable user setting of constants needed for positional calculation; microstepping setting, gear ratio and stepper motor degrees/step.

I may turn this design into a semi commercial venture; figuring out all the little parts to build this has taken a lot of time. It would include a build manual, DWG files for someone cutting the wood on a CNC, drawings for someone just using a circular saw/chop saw, a link to all the different fasteners on the fastener website I like, the software, 3d print files for all the 3d printed parts (the drive gear, a little plate which holds the motor/homing sensor, a diagram showing how to wire the tic to the homing switch and everything. If anyone here is interested in testing, when I get mine done I can share the design details and you can give me some feedback. On the other hand, if you're the sort of person who knows what grbl is, then you can probably do all this by yourself!

I think the younger/more technical makeup of ASR is not the best audience for such a product, but there are a lot of less technical speaker designers out there who could really use a good measurement platform.

 

[suttondesign]

I have a CNC router, and can make baffles like this out of MDF, if that would be useful for experimentation. That said, I think the idea of a "community speaker" would be one that could be made without a 3D printer or a CNC router. I think it would be best to make a design that can be made with MDF, a table saw, and a router.

Are there not web-based firms who will just spit out a 3-D printed thing if you supply the file? I was under the impression this was not too expensive these days.