Some years ago I got a pair of ACR TT50 titan dome midranges (page 13: http://www.acr.ch/uploads/media/ACR_LAUTSPRECHERKATALOG_90ER_JAHRE.pdf). Other than just trying them out actively crossed over at ~700Hz and running "full-range" (i.e, no tweeter) otherwise, they've been sitting in the drawer. But now is the right time to put them in use.
This is going to be a 3-way using 10" aluminium cone bass from Scan-Speak Discovery series (26W/4534G00; haven't ordered them yet) and aluminium-magnesium dome tweeter from Seas (22TAF/G) - hence the name. Crossover shall be ~700Hz active 4th order and passive 5,5 kHz 2nd order for mid and 3rd order for tweeter. They shall be a modular construction - separate boxes for bass and mid plus tweeter.
The mid-high boxes are glued and waiting to be routered and finished. As you can see, I managed to make a small screw-up on one panel that will be hidden behind filler and paint. The measured frequency response of TT50 is agreeable with manufacturers published curve. And if the tweeter and mid had similar grilles, they'd be a perfect pair
This is going to be a 3-way using 10" aluminium cone bass from Scan-Speak Discovery series (26W/4534G00; haven't ordered them yet) and aluminium-magnesium dome tweeter from Seas (22TAF/G) - hence the name. Crossover shall be ~700Hz active 4th order and passive 5,5 kHz 2nd order for mid and 3rd order for tweeter. They shall be a modular construction - separate boxes for bass and mid plus tweeter.
The mid-high boxes are glued and waiting to be routered and finished. As you can see, I managed to make a small screw-up on one panel that will be hidden behind filler and paint. The measured frequency response of TT50 is agreeable with manufacturers published curve. And if the tweeter and mid had similar grilles, they'd be a perfect pair
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Update -- mid/high boxes are almost there (filling, sanding and painting not done yet). Crossover is done and I guess I got it right on the first try. Need to take some measurements with a calibrated mic, I don't think my uncalibrated DIY mic is accurate above 5 kHz or so. Anyway, they sound great crossed at ~620 Hz to my existing bass modules (two Fane Sovereign 8-225 in each). This Seas 22TAF/G is a great little tweeter
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Another update - went for elliptical crossover for midrange low-pass. This only required ~35uH inductor in series with the already in place 4,7 uF capacitor and took care of the 12 kHz peak. The result is cleaner impulse response and makes the drivers integrate better.
Progress is quite slow, have yet to order bass drivers. And now I'm thinking about SB Acoustics SB23NACS45-8 in a ~30 liter sealed box instead of Scan-Speak Discovery. I think 8" would integrate better with a 2" dome. Anyone used that SB Acoustics? How does it sound?
Progress is quite slow, have yet to order bass drivers. And now I'm thinking about SB Acoustics SB23NACS45-8 in a ~30 liter sealed box instead of Scan-Speak Discovery. I think 8" would integrate better with a 2" dome. Anyone used that SB Acoustics? How does it sound?
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Looking good! No clue about the SB other than what's posted here:
SB Acoustics SB23NACS45-8 Testing - Techtalk Speaker Building, Audio, Video Discussion Forum
http://medleysmusings.com/sb23nacs45-8/
GM
SB Acoustics SB23NACS45-8 Testing - Techtalk Speaker Building, Audio, Video Discussion Forum
http://medleysmusings.com/sb23nacs45-8/
GM
Very pretty drivers you can see them measure here.
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Where they turn in a very decent performance.
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Where they turn in a very decent performance.
Sir I commend your pun for the name of your project.
Thank you! It naturally popped into my mind after discussing metal drivers with local audio hobbyists. I was warned they'll surely sound harsh and piercing, screeching my ears off; my response was "Well, I still want to take this on; good idea or not, all metal it shall be!"
Really nice!
As for Alu drivers sounding harsh, nothing is further from the truth, if metal cone and metal dome drivers operate strictly withing intended frequencies, and the 'ringing' of nasty break up frequency of hard cones is kept well out of the range, especially if sharply cut off with 4th order, they are very low distortion, excellent drivers.
I'd like to hear them very much!
As for Alu drivers sounding harsh, nothing is further from the truth, if metal cone and metal dome drivers operate strictly withing intended frequencies, and the 'ringing' of nasty break up frequency of hard cones is kept well out of the range, especially if sharply cut off with 4th order, they are very low distortion, excellent drivers.
I'd like to hear them very much!
Indeed, breakup mode has to be properly dealt with. As for ordering the proper bass drivers, spring is here, weather is nice and my bicycling hobby is already eating up all the disposable income and time, so I'm yet procrastinating
Veikko, if you're interested in hearing them, throw me a private message
Two years have passed, and finally I'm about to finish this project. After a lot of deliberation and rumination the bass driver is going to be Hi-Vi M8A1, the passive and active crossover sections have been revised several times and the bass cabinets are in the final stages of finishing.
The bass cabinet is around 30 liters (~1 cu. ft.), tuned to around 30 Hz. The port is downfiring and the speaker will sit on three legs, two front ones made of 15x30 mm (~0,6x1,2") aluminium profile and the rear one from white beech shelf bracket, giving 50 mm (~2") of clearance between floor and port. The finish will be natural linseed oil mixed with artist oil paints (burnt umber plus a dash of ultramarine). The final layer will be karnauba wax, already tried it out on my oiled coffee table and it brings out wood grain even more and gives a very nice, yet natural, sheen. There are some scratches on the front panels that are too deep to sand out - they've been lying around in my friends garage for 2 years, after all - but its OK for me. Wabi-sabi.
Crossover points are 520 Hz BW 3rd order and 4,1 kHz 2nd order low-pass with notch and 3rd order high-pass. With felt applied to the front panel and a little bit of EQ (-3 dB, 805 Hz, Q=2; +1 dB, 3,18 kHz, Q=3,5; -1 dB, 7,97 kHz, Q=2) I got better than +/-1 dB linearity above 1 kHz (ignore roll-off above 10 kHz, my mic is uncalibrated). Horizontal dispersion is very wide and even, vertical is somewhat restricted due to high crossover point, but this is to be expected when using wide-flanged dome midrange.
Overall, I'd consider this quest almost complete and an overall success.
The bass cabinet is around 30 liters (~1 cu. ft.), tuned to around 30 Hz. The port is downfiring and the speaker will sit on three legs, two front ones made of 15x30 mm (~0,6x1,2") aluminium profile and the rear one from white beech shelf bracket, giving 50 mm (~2") of clearance between floor and port. The finish will be natural linseed oil mixed with artist oil paints (burnt umber plus a dash of ultramarine). The final layer will be karnauba wax, already tried it out on my oiled coffee table and it brings out wood grain even more and gives a very nice, yet natural, sheen. There are some scratches on the front panels that are too deep to sand out - they've been lying around in my friends garage for 2 years, after all - but its OK for me. Wabi-sabi.
Crossover points are 520 Hz BW 3rd order and 4,1 kHz 2nd order low-pass with notch and 3rd order high-pass. With felt applied to the front panel and a little bit of EQ (-3 dB, 805 Hz, Q=2; +1 dB, 3,18 kHz, Q=3,5; -1 dB, 7,97 kHz, Q=2) I got better than +/-1 dB linearity above 1 kHz (ignore roll-off above 10 kHz, my mic is uncalibrated). Horizontal dispersion is very wide and even, vertical is somewhat restricted due to high crossover point, but this is to be expected when using wide-flanged dome midrange.
Overall, I'd consider this quest almost complete and an overall success.
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I've noticed thesimilarity myself. If I'm not mistaken, it was used in Thiel CS5. The only "problem" with this driver is elevated 3rd HD around 4kHz, corresponding to the break-up at 12 kHz. Even then, it doesn't exceed 1% and is very benign.
Almost there, the stain needs to dry for a few days more before I can start waxing.
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On a side note, I'm also working on a 2-way monitor speaker using the same HiVi M8A woofer in a similarily tuned box and SB Acoustics SB26ADC tweeter on a Monacor waveguide. There will be 2 pairs of these, one for rear speakers in my setup, and one for a friend. Preliminary results are promising
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