I started a little project that might interest some of you. I feel we're really getting short-changed by manufacturers like ScanSpeak and SBA when they supply waveguide tweeters to the retail companies but not us. 3D printing inspired me to think maybe there was a solution. Once I got up to speed on the CAD software (Autodesk Fusion 360 is awesome for the untrained) I've started moving forward with some designs. The goal will be to create application specific waveguides. Applications will basically define the woofer size intended, acoustic offset, low frequency cutoff needed, and directivity at the crossover that matches the woofer DI. I see three or 4 ultimate designs: one for 12-15cm woofers, one or two for 15-17cm woofers, and one for a 22cm woofer. I'll be designing the first guide to be used with the SB Acoustics SB26ADC-C000-4. Once the best practices are established, I'll move on to my Transducer Lab ceramic tweeter. After that I'm hoping someone will supply a few good candidates, like a good Scanspeak.
The first application is a 5" guide intended to match a 12-15cm woofer and has a 3.5dB spread from 0 to 60 degrees at 2.5khz - about the same as the intended woofer. AC depth of these woofers are about .75" - 1". I'll be doing both a .75" and 1" deep guide to gauge the impact on DI at 2.5khz. I'll also being two versions at each depth, one where the flare is tangent to the baffle face (and so flare radius is out of my hands) and one where it isn't and allows me to enter my own radius. For the designs so far the radius is about 2.1" for the tangent version, and I specified 4" radius for the non-tangent version.
A phase shield will be in all designs, though I will test without just to see the difference. I basically copied the size the SB tweeter uses.
I'm starting with round guides but will move on to elliptical also.
I intend to make all of the resulting designs available for free to anyone. My hope is to quantify the actual differences between design parameters and end up with very high quality designs for handful of popular tweeters for the entire DIY community.
BTW if anyone has access to an industrial printer for say, resin, and can help out (I'll pay material and shipping costs of course) let me know. Retail prices for the service are still high enough that it isn't feasible to pay for 20 prototypes that will end up in the garbage afterward. In an unfortunate turn of events the person that was going to no longer can. Luckily another hobbyist will help making some in wood with a CNC (which I can easily attach the printed phase shields to) so design and prototyping will still move forward, but in the future the 3D print will probably be the most accessible so I'm hoping to source that at reasonable cost.
The first application is a 5" guide intended to match a 12-15cm woofer and has a 3.5dB spread from 0 to 60 degrees at 2.5khz - about the same as the intended woofer. AC depth of these woofers are about .75" - 1". I'll be doing both a .75" and 1" deep guide to gauge the impact on DI at 2.5khz. I'll also being two versions at each depth, one where the flare is tangent to the baffle face (and so flare radius is out of my hands) and one where it isn't and allows me to enter my own radius. For the designs so far the radius is about 2.1" for the tangent version, and I specified 4" radius for the non-tangent version.
A phase shield will be in all designs, though I will test without just to see the difference. I basically copied the size the SB tweeter uses.
I'm starting with round guides but will move on to elliptical also.
I intend to make all of the resulting designs available for free to anyone. My hope is to quantify the actual differences between design parameters and end up with very high quality designs for handful of popular tweeters for the entire DIY community.
BTW if anyone has access to an industrial printer for say, resin, and can help out (I'll pay material and shipping costs of course) let me know. Retail prices for the service are still high enough that it isn't feasible to pay for 20 prototypes that will end up in the garbage afterward. In an unfortunate turn of events the person that was going to no longer can. Luckily another hobbyist will help making some in wood with a CNC (which I can easily attach the printed phase shields to) so design and prototyping will still move forward, but in the future the 3D print will probably be the most accessible so I'm hoping to source that at reasonable cost.
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