Ultra is (digital) preamp for active 4 way dipoles

Valentino

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Community Curator
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Jul 6, 2024
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Location
Hamar, Norway
In 2009 ha friend helped me costruct and have manifactured a 3-way dynamic dipole system with closed box subwoofers operating below 45 Hz. The dipoles themselves operate below the dipole peak up to appx 6 kHz where the tweeter becomes too large and beaming starts. We have to thank Rudolf Finke for his work on this way of thinking dipoles: A small baffle or maybe no baffle at all, trying to make the radiation pattern as close to a theoretic dipole as possible.
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Left main speaker in the nude. Two Beyma 12" in a small H frame, two nude SEAS W15CH and one nude Mundorf AMT2340. The pic is from before I replaced my Yamaha WXC-50 and Squeezebox Touch with the Ultra.
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Old pic from the rear wall. As you may understand I do not use the Ultra HDMI. Listening position pretty close about 1,5 m from the speakers. 10 cm acoustic tile above the listening triangle. Large distance to side walls, 1 m from speakers to front wall.
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I use a Topping L30 headphone amp instead of the onboard one. I also use a Cambridge Audio Alva Duo instead of the onboard Phono amp.
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My turntable is a modified but you cannot see that German treasure from 1973 with a new Bokrand tonearm (my father bought the record in 1963 or so).
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Details above. I've always used class D amplification and DSP crossovers/eq. To use something else you'd have to be dipole hero Siegfried Linkwitz. Until MiniDSP came along with their Flex Eight I had a PC running the filters under Console and a RME Fireface UD sound card. That PC is now running LMS for the setup. Peak volume in the listening position is a Mahlerian 108 dB(A).
 
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This is the system acoustic impulse response measured in the listening position. Linear scale, 10% is -20 dB. Such a behavior is impossible without DSP.
Please note that the WiiM DSP is not involved here, only the ones in the MiniDSP Flex Eight.
 
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Speaker system frequency response.
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Left speaker waterfall. Right speaker is quite similar.
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Bartok in the winter sun. A system upgrade now would have to be the new and modestly priced MiniDSP PocketADC between the phono amp and Ultra, and move the CD player to Line In. The Ultra analog input specs could have been better, but the CD player is only used for checking out if the music on a CD is worth ripping anyway. And look good of course. I love the Yamaha facias.
 
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