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The project started out a bit backwards or, literally, from top to down. I acquired the tweeters for a fair price and wanted to build something around them. One option would've been to start creating something of my own, but at this point it would've too much. Life and such sometimes gives directives you can not avoid 
Anyhow, tweeters were acquired and I started evaluating designs which I could find publicly available. There wasn't really many and Jon's Modula MT XE shined, with a big margin. There is lot of thought put into the design and the pdf was/is very insightful. Jon was also very supportive during the build process. I wonder why so few have built these. Or publicly admitted it
The waveguide
Biggest issue with this project was the waveguide. The legendary MCM waveguides are no longer available, and there aren't that many substitutes that work with D2608/9130. After a while I grew tired of trying to fing suitable waveguide and had a chat with our local (I live in Finland) DIY community. Helpful fellow hobbyist offer to make these and we ordered 1 meter (3') of POM bar. Little bit of modeling and testing plus CNC machining and voila, user friendly waveguide. Only thing you need, is sealing tape and four wood screws to attach the tweeter. Now I have 24 waveguides to spare, I wonder if I'll ever build a speaker without one
The cabinet
I had to make some sacrifices with the cabinet. First of all, it's white. Blasphemy, I know The other one is size and shape. 0.75cu PE box is, well, a bulky fo me. Original design is 10" wide, I made it 8.5" wide and extended the cabinet to be a floorstander. Lower compartment is sealed off and reserved for crossovers.
Internal volume is approx. 22 liters and port tuning around 40Hz. 40Hz sounded the best, being a compromise between extension and mid bass attack.
The crossover
Nothing out of the ordinary, if we count out the mad science of Jon's. Actually, the crossover layout isn't that daunting at all, compared to Jon's other designs I followed the specs more or less to the letter, choosing a bit cheaper coil for bass section. Components are glued to 6mm MDF boards with SuperFix and voicing components are connected with terminal blocks. That way they are easy to change if needed. I experimented with the treble level (R4) for a while and I ended up with the default value, that seemed to bring the sparkle I wanted yet keeping the voicing analytic but calm. I still wonder what the other resistor (R6) does. I tried default and extremes and I'm not sure if I heard any differences
Placement
As with any boxed loudspeaker, these want to be at least 2' (measured from baffle) from concrete wall in order to avoid midbass humps. Other than that, they seem to be quite easy to place. Toe inn does not make much difference although they need to be a bit toed inn if side walls are close. Otherwise stereo imaging disintegrates.
The Sound
Wow. It has Sound with capital letter. As Jon describes, they are never shouty even with higher levels. There are limitations what on 6.5" element can produce in shere SPL, but with my typical listening levels there is no hint of reaching the limits. They just produce the sound and sort of disappear. With ease.
I presented these in our local DIY event this month. Many visitors complemented the sound being calm, balanced and precise. Here is a short write up of the event. I wanted to present publicly available designs so that beginners like me would have more confidence in starting the DIY journey. Not everyone can design a speaker but most enthusiasts/diy-curious can build cabinets and solder crossovers.
I am very pleased with the speakers and I assume they will be my reference speakers for years.
Joni
Anyhow, tweeters were acquired and I started evaluating designs which I could find publicly available. There wasn't really many and Jon's Modula MT XE shined, with a big margin. There is lot of thought put into the design and the pdf was/is very insightful. Jon was also very supportive during the build process. I wonder why so few have built these. Or publicly admitted it
The waveguide
Biggest issue with this project was the waveguide. The legendary MCM waveguides are no longer available, and there aren't that many substitutes that work with D2608/9130. After a while I grew tired of trying to fing suitable waveguide and had a chat with our local (I live in Finland) DIY community. Helpful fellow hobbyist offer to make these and we ordered 1 meter (3') of POM bar. Little bit of modeling and testing plus CNC machining and voila, user friendly waveguide. Only thing you need, is sealing tape and four wood screws to attach the tweeter. Now I have 24 waveguides to spare, I wonder if I'll ever build a speaker without one
The cabinet
I had to make some sacrifices with the cabinet. First of all, it's white. Blasphemy, I know
The other one is size and shape. 0.75cu PE box is, well, a bulky fo me. Original design is 10" wide, I made it 8.5" wide and extended the cabinet to be a floorstander. Lower compartment is sealed off and reserved for crossovers.Internal volume is approx. 22 liters and port tuning around 40Hz. 40Hz sounded the best, being a compromise between extension and mid bass attack.
The crossover
Nothing out of the ordinary, if we count out the mad science of Jon's. Actually, the crossover layout isn't that daunting at all, compared to Jon's other designs
I followed the specs more or less to the letter, choosing a bit cheaper coil for bass section. Components are glued to 6mm MDF boards with SuperFix and voicing components are connected with terminal blocks. That way they are easy to change if needed. I experimented with the treble level (R4) for a while and I ended up with the default value, that seemed to bring the sparkle I wanted yet keeping the voicing analytic but calm. I still wonder what the other resistor (R6) does. I tried default and extremes and I'm not sure if I heard any differences Placement
As with any boxed loudspeaker, these want to be at least 2' (measured from baffle) from concrete wall in order to avoid midbass humps. Other than that, they seem to be quite easy to place. Toe inn does not make much difference although they need to be a bit toed inn if side walls are close. Otherwise stereo imaging disintegrates.
The Sound
Wow. It has Sound with capital letter. As Jon describes, they are never shouty even with higher levels. There are limitations what on 6.5" element can produce in shere SPL, but with my typical listening levels there is no hint of reaching the limits. They just produce the sound and sort of disappear. With ease.
I presented these in our local DIY event this month. Many visitors complemented the sound being calm, balanced and precise. Here is a short write up of the event. I wanted to present publicly available designs so that beginners like me would have more confidence in starting the DIY journey. Not everyone can design a speaker but most enthusiasts/diy-curious can build cabinets and solder crossovers.
I am very pleased with the speakers and I assume they will be my reference speakers for years.
Joni
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