Nice! Happy to donate more when I start integrating the TW29TX into my next project. Meanwhile, I'm still pretty new to waveguides so forgive me if this is covered a lot elsewhere---it is pretty obvious that above 10khz the phase shield on the TW29TX is causing a really exaggerated dip off axis. Do the other benefits of the phase shield outweigh the dip? When the dip is that far off axis is it that big of an issue anyway? My hearing doesn't go that high so maybe a moot point but just curious what to look for in all of this.
Are the .stl files for these waveguides available somewhere? On the soma sonus website, I could only find 6.5" waveguide with a circular mouth. I would really appreciate getting my hands on them!
I've revisited circular waveguides for the SB26CDC, to see if I improve upon early attempts with what I've learned since then. Since the SB26CDC models well in ABEC, I did investigate circular waveguides with both my constant radius contour, and an OS-SE contour. None of them improved on the elliptical designs I already had, and I think the following measurements validate that.
Asking for the .stl files for the smaller circular sbc26 waveguides for one last time, before I go ahead and print out the 6.5" inch one.
My situation is that I can only book the library's printer for 8 hours at a time, and that means that with the 6.5" waveguide I will have to use very low fill density. I would much rather do a smaller guide and print it with higher fill / quality. The elliptical ones are, aesthetically, very unpleasing to me. It just can't be helped. And routing will be tough, while I already have a set up to do circular routing easily.
By the way, The 6.5" inch guide measures 190.5mm in the printing software once I scale it to mm (2540% uniform scaling). This seems rather big for 6.5, and by diameter, the mounting hole is more similar with 7.5-8 inch bass-mid drivers. Did I mess up something, or are the guides just classified a little differently?
PS. I haven't bought the sbc26 tweeters yet, so I am open to suggestions for waveguides suited for other tweeters that would be smaller and circular. Thank you!
My situation is that I can only book the library's printer for 8 hours at a time, and that means that with the 6.5" waveguide I will have to use very low fill density. I would much rather do a smaller guide and print it with higher fill / quality. The elliptical ones are, aesthetically, very unpleasing to me. It just can't be helped. And routing will be tough, while I already have a set up to do circular routing easily.
By the way, The 6.5" inch guide measures 190.5mm in the printing software once I scale it to mm (2540% uniform scaling). This seems rather big for 6.5, and by diameter, the mounting hole is more similar with 7.5-8 inch bass-mid drivers. Did I mess up something, or are the guides just classified a little differently?
PS. I haven't bought the sbc26 tweeters yet, so I am open to suggestions for waveguides suited for other tweeters that would be smaller and circular. Thank you!
Last edited:
Hi AllenB,
Is the MTM not an exception to this rule, i.e. eleptical usefull to :
1) reduce the space to space center of the two woofer to make them more point source
2) reduce the vertical pattern of the tweeter cause it is sandwiched between two vertical sound waves formed by the two woofers while still needing due to the MTM to be crossed over low -preferabily 2000 hz max- ?
While if you look at Living Voice MTM,they use a big wave guided 13 cm scan-speak tweeter offseted in a side between the two big 7" woofers, but not sure they bother much about that.
Is the MTM not an exception to this rule, i.e. eleptical usefull to :
1) reduce the space to space center of the two woofer to make them more point source
2) reduce the vertical pattern of the tweeter cause it is sandwiched between two vertical sound waves formed by the two woofers while still needing due to the MTM to be crossed over low -preferabily 2000 hz max- ?
While if you look at Living Voice MTM,they use a big wave guided 13 cm scan-speak tweeter offseted in a side between the two big 7" woofers, but not sure they bother much about that.
Last edited:
Zappa> what is your intended usage? For a nominal 18cm driver, I would use the 6" waveguide, not the 6.5". The 5" would even work better than no waveguide. BTW for a given width, an elliptical is always less material and print time than a circular. And using the template to route the hole is so simple, I really don't understand people's resistance to this. There is no way any of these waveguides are going to print in 8 hours, so you are going to have to figure something out there regardless of what you use.
AllenB> I don't think we can make generalizations like that. Geddes admitted his waveguide would be better on-axis if it were asymmetric. JBL are all asymmetric. Genelec all asymmetric. Those guys aren't in the business of making "second best". And at least in mine, the vertical response is not as different as one might expect from the horizontal response. And it is different in a way that might be better, depending on the design.
diyiggy> If you are still in the school that closer is better, than yes elliptical allow that. I've moved to the 1.2-1.4x wavelength school, but even there I tend to find that I get the best baffle diffraction signature when the tweeter is closer to the top edge than a circular waveguide would allow. Regarding MTM, I have done some initial investigation with VituixCAD, and yes, MTM still require the closest spacing possible for the smoothest floor and ceiling reflection. And this is where the waveguide shines, since it can keep a tighter vertical directivity even in the treble. I think waveguides are the thing that finally make MTM work, all the advantages and none of the disadvantages.
AllenB> I don't think we can make generalizations like that. Geddes admitted his waveguide would be better on-axis if it were asymmetric. JBL are all asymmetric. Genelec all asymmetric. Those guys aren't in the business of making "second best". And at least in mine, the vertical response is not as different as one might expect from the horizontal response. And it is different in a way that might be better, depending on the design.
diyiggy> If you are still in the school that closer is better, than yes elliptical allow that. I've moved to the 1.2-1.4x wavelength school, but even there I tend to find that I get the best baffle diffraction signature when the tweeter is closer to the top edge than a circular waveguide would allow. Regarding MTM, I have done some initial investigation with VituixCAD, and yes, MTM still require the closest spacing possible for the smoothest floor and ceiling reflection. And this is where the waveguide shines, since it can keep a tighter vertical directivity even in the treble. I think waveguides are the thing that finally make MTM work, all the advantages and none of the disadvantages.
Hi, I was in the school of 1 to 1.2 x the wave length before you discovered it if I remember, so the "still" doesn't apply 
... but as you say : MTM is scary (I have to because the drivers needs to be twiced for the acurate sensivity of the design, alas. But I unfornatully read somewhere than higher than one WL was too much for the MTM, hence the ask : cause 2000 hz is that WL with two 5.1/4 with few spacing ! So yes I have the feeling the WG is mandatory to help the tweeter to go that low.
Thanks for your input...
I hesitate still between the elleptical (and also because I am a little beginner at routing) because of this ctc or an offsetting of a 5" circular WG à la Living voice or at worst an asymetric of the two 5.1/4" woofers .... As I have pain to find a good cheap 2000 hz tweeter capable, the adc in one of the Somasonus will be very welcome (well I made a donation for the 6.5" but didn't print the stl, I have a snail house on the back, lol ! )
... but as you say : MTM is scary (I have to because the drivers needs to be twiced for the acurate sensivity of the design, alas. But I unfornatully read somewhere than higher than one WL was too much for the MTM, hence the ask : cause 2000 hz is that WL with two 5.1/4 with few spacing ! So yes I have the feeling the WG is mandatory to help the tweeter to go that low.Thanks for your input...
I hesitate still between the elleptical (and also because I am a little beginner at routing) because of this ctc or an offsetting of a 5" circular WG à la Living voice or at worst an asymetric of the two 5.1/4" woofers .... As I have pain to find a good cheap 2000 hz tweeter capable, the adc in one of the Somasonus will be very welcome (well I made a donation for the 6.5" but didn't print the stl, I have a snail house on the back, lol ! )
Hey auger, thanks for the reply>
I want to make more sloping directivity speakers than my current ones, to see if they work a lot better in a room I am not keen on treating acoustically. I have a sub I'm handing them over to with active crossovers on the speaker as well on the sub, so low frequency extension is optional.
I think 6.5" would be ideal driver size, since the speaker won't be overly big, but can still work well enough without a sub if I ever need to do that. 8" is needlessly big and I get to 3D printing problems if I want a similarly sized waveguide. 5.25" Would be pretty acceptable as well, that's the size of the speakers I currently have build here.
My current plan is to print the 6.5" circular guides with that low density fill in the library and fill them up with epoxy. I have not heard of people doing that, but it's not immediately obvious to me why it woudln't work. Maybe some other fill is better? I am open to suggestions. The library prints are practically free, so I want to see if I can make them work first. I'm new to printing so I consider it free experience as well. Only problem is that the printer is in another town, and I had to convince the printer guy to put the printer on for me when I send the files. I doubt he's eager to keep doing this for several prints, so prototyping is limited to couple of tries.
Depending on the quality of the print, I might then end up ordering commercial prints, and possibly design and print the baffles too, for the finished speaker.
I strongly prefer the look of circular guides and also, because of the printer being in another town, it is not so simple for me to print the guides for elliptical routing either, and I would want to keep the option open for traditional wooden front baffle.
I want to make more sloping directivity speakers than my current ones, to see if they work a lot better in a room I am not keen on treating acoustically. I have a sub I'm handing them over to with active crossovers on the speaker as well on the sub, so low frequency extension is optional.
I think 6.5" would be ideal driver size, since the speaker won't be overly big, but can still work well enough without a sub if I ever need to do that. 8" is needlessly big and I get to 3D printing problems if I want a similarly sized waveguide. 5.25" Would be pretty acceptable as well, that's the size of the speakers I currently have build here.
My current plan is to print the 6.5" circular guides with that low density fill in the library and fill them up with epoxy. I have not heard of people doing that, but it's not immediately obvious to me why it woudln't work. Maybe some other fill is better? I am open to suggestions. The library prints are practically free, so I want to see if I can make them work first. I'm new to printing so I consider it free experience as well. Only problem is that the printer is in another town, and I had to convince the printer guy to put the printer on for me when I send the files. I doubt he's eager to keep doing this for several prints, so prototyping is limited to couple of tries.
Depending on the quality of the print, I might then end up ordering commercial prints, and possibly design and print the baffles too, for the finished speaker.
I strongly prefer the look of circular guides and also, because of the printer being in another town, it is not so simple for me to print the guides for elliptical routing either, and I would want to keep the option open for traditional wooden front baffle.
Time for an update! I've landed on some good designs for the Satori and Scanspeak tweeters, and hope to have the .stl/.stp files uploaded to my website by the end of the week. Now I can scale the design up to 8" and down to 4" for those tweeters.
I won't post all the variants, but I tried different diameter phase shields, and tried using a hole in the middle of the phase shield. I also played with shape of the profile near the throat, since that has a huge effect.
Here are the Scanspeak 6640 results:
I won't post all the variants, but I tried different diameter phase shields, and tried using a hole in the middle of the phase shield. I also played with shape of the profile near the throat, since that has a huge effect.
Here are the Scanspeak 6640 results:
Will you be revisiting the SB26ADC with the hybrid contour? I've been designing my own waveguide using a logarithmic spiral profile like joseph crowe, and through AKABAK found that the OS radius in the throat cleared up nasty stuff out to 180°, it's likely because the dome is very flat and yields more of a plane wave.Time for an update! I've landed on some good designs for the Satori and Scanspeak tweeters, and hope to have the .stl/.stp files uploaded to my website by the end of the week. Now I can scale the design up to 8" and down to 4" for those tweeters.
I won't post all the variants, but I tried different diameter phase shields, and tried using a hole in the middle of the phase shield. I also played with shape of the profile near the throat, since that has a huge effect.
Attachments
Promising results on the SB26ADC. I may have to give that one another look. The phase shield appears to not make that much difference, which indicates not alot of the upper HF is reaching the tip of the done due to higher internal damping. That may be a good thing.
As a side note, did you plan on any WGs for the Audax TW034? I know that Jantzen makes one, but its expensive and doesn't fit the dome that optimally.
Anyways, very nice work you're doing! It's nice to see there are still kind people in this world willing to share their knowledge.
As a side note, did you plan on any WGs for the Audax TW034? I know that Jantzen makes one, but its expensive and doesn't fit the dome that optimally.
Anyways, very nice work you're doing! It's nice to see there are still kind people in this world willing to share their knowledge.