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TOPIC: AINOgradient - a 4-way active dipole speaker

AINOgradient - a 4-way active dipole speaker 3 years 2 months ago #11970

  • Juhazi
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My project is fully described in this forum thread www.diyaudio.com/forums/multi-way/231353...speaker-project.html



Idea
To make a partially dipole speaker in the spirit of the legendary Gradient 1.3.

System
Versions:
AINOgradient
AINOgradient Neo
AINOgradient NeoB
Dipoles need lots of eq and measurements/adjustments, so a minidsp 4x10HD is the way to control it. The lowest bass is a sealed box, midrange is true dipole 150-4kHz, highs with a ribbon and a backside assisting dome. Power amplifiers are B&O ICEpower 125 and 50 modules per speaker. My AV receiver is the input selector and feed analog signal to minidsp. Too bad that it does not have digital out with volume control. I used UMIK-1 and REW for measurements. All minidsp settings were done without REW-automation.

Measurements

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AINOgradient - a 4-way active dipole speaker 3 years 2 months ago #11980

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With dipoles, it is crucial to know how directivity really is, 0-90¤ and 90-180¤. Other difficult aspect is distortion at high levels, because of poor acoustic efficiency of open drivers, specially with "nude drivers like in AINOgradient. I have not seen exactly comparable data of other dipoles, but I am rather sure that AINOs perform exceptionally well!

The sound of dipoles depends very much on positioning in the room (wall bounces) and room's reflectivity. The strong backwards sound must not interfere with forward sound, but compliment it By smooth late reflections. These issues can be seen in room response RTA, decay graphics and RT values .

More measurements:









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AINOgradient - a 4-way active dipole speaker 3 years 2 months ago #12008

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I have done PowerPoint presentations of AINOgradient. If you want to get one, please email me to juha.sirkka(*)fimnet.fi
Summary - 4 pages
Full - 27 pages

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AINOgradient - a 4-way active dipole speaker 3 years 2 months ago #12047

  • devteam
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Wow.. that's really neat info Juha! Is that a product on sale? Maybe we could put it in the "powered by miniDSP section"?
www.minidsp.com/applications/powered-by-minidsp
Keep us updated, very neat work!

Devteam
MiniDSP, building a DIY DSP community one board at a time.
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AINOgradient - a 4-way active dipole speaker 3 years 2 months ago #12081

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Thank You for asking,
but this is purely a personal project, I don't have any commercial interests. This is too far-out and unorthodox composition for marketing, but I am happy if any diy'er wants to use/copy my ideas and documented solutions and experience.

This project can be published in your Project gallery. Please give email address straight to Devteam/you! My email is in the previous messge
Juha
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AINOgradient - a 4-way active dipole speaker 2 years 2 months ago #17620

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AINOgradient NeoC

minidsp 4x10HD-controlled, 4-way active hybrid sealed-dipole speaker
SEAS L26ROY (sealed monopole), Beyma MW12Nd, BG Neo8PDR, BG Neo3PDR
B&O ICEpower class D amplifiers, 125+50 per speaker

I finally pulled the trigger and purchased a pair of B&G Neo3PDR tweeters (without back cup or faceplate). Got them from Spain by eBay. Unused, in plastic bags. First I put them in normal vertical position in the frame, but measured response was not what I expected. Hopla, turn the thing 90¤ and it gets acoustically narrower because it does not fill the opening in the frame (see pic) Raw measurements, some eq, delay setting and xo set LR4 at 3500Hz - bingo!

Dipole action past 6kHz, excellent! The dip in direct response at 7kHz does not show in backside response, so it might be a "cavity effect" and managed with a new frame. Rear radiation was attenuated in NeoB, now it is equal and room decay measurements look more nice. There is more sparkles in the sound too, which is nice.

I will make new plywood frames for Neos in near future. Tweeter must have open space in the frame to maintain dipole action so high in F. Vertical directivity is not perfect because of too much M-T distance but tolerable, and the xo-range beam can be tilted with delay adjustment, now it is a bit upwards.
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AINOgradient - a 4-way active dipole speaker 1 year 3 months ago #22495

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AINOgradient Neo83

I ended up to purchasing Neo3PDR tweeters too, it was obvious tha the large horn/magnet structure of Fountek dispturbed backwards radiation and back-to-back tweeters were too much a compromise. Crossover between subwoofer and lower mid is LR2, others LR4.

With planar mids and tweeters and narrow open baffle I was able to push acoustic dipole radiation pattern up to almost 7kHz and almost seamlessly. See polar graphics! My measurements are mostly done indoors and there are lots of reflection below 400Hz.

I attended a Finnish DIY-audio event held in May 2015, and AINOgradients were voted to give "Best Sound in show"!
Pictures from the event in this link



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AINOgradient - a 4-way active dipole speaker 1 year 3 months ago #22691

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I found some more smoothed polar graps, based on same measurements. Backside measurement has only 4 different angles, frontside has 6.
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AINOgradient - a 4-way active dipole speaker 5 months 1 week ago #28234

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Updated presentation of the project ready for download here, wellcome!
drive.google.com/file/d/0BzUGcoofhVkAbjR...eFk/view?usp=sharing
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AINOgradient - a 4-way active dipole speaker 2 months 14 hours ago #30192

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Did you have any impedance problems with minidsp vs. icepower, have read somewhere that it could be a problem?
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AINOgradient - a 4-way active dipole speaker 2 months 10 hours ago #30193

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Thank You for asking, but no I haven't recognized any such problems. Spl response, distortion and dB scale are clean and wide. I use 50asx2 and 125asx modules without any added circuits. I have used several other home-hifi integrated and power amplifiers too for testing and measuring, without any changes in measured performance.
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