Just got my Digmoda 552 hooked up!

[studiotech]

Sorry for the quality....cell phone camera. Got these 2 weeks ago and finally hooked everything up for a test rig. What you see is my old OB woofers, a test box for various midrange evaluation(currently with a little tang band in there) and the CSS LAR1 ribbon filling in for future RAALS dues to budget.

Greg

[LineSource]

I am very interested in your step-by-step development work with the Digmoda 552 for this 3-way dipole configuration and hope you can find the time for several informative posts. Your work might start a group purchase of the Digmoda 552 and/or a common speaker set.

From my listening experience:
1) under 100Hz, the H-baffle reduces the cone-displacment enough to sound better than a identical width no-wings flat baffle
2) A single 8"-10" midrange on a minimal baffle, even with some dispersion compromise, sounds better than a smaller driver or MTM
3) a dipole tweeter is very important on a minimal baffle. Experimenting with dipole ribbons and open back compression drivers is worthwhile.

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OLD Wholesale pricing From DigModa in 2009 AV Forum post:

"Thank you for your request for info about KSC's digmoda amplifier series of products. These products are available now and are powered by ICE POWER® amp modules and utilize KSC's proprietary DSP design and easily programmable D-PRO® GUI software.


DDC552 product uses the 500ASP + 500A+ 250A modules with DSP and is a 6 inch by 18.6 inch rectangular plate configuration. This amp has mono input for 3-way loudspeaker applications. Sample pricing is: $712; 1 - 49pcs, & $583; 100-249pcs. FOB San Diego.

DDC1150 product uses the 1000ASP + 1000A+ 500A modules with DSP and is a 6 inch by 20.64 x 7 x 3.6 inch rectangular plate configuration. This amp has mono input for 3-way loudspeaker applications. Sample pricing is: $930; 1 - 49pcs, & $747; 100-249pcs. FOB San Diego.



Acoustic Elegance Speakers: IB15 are 8ohm drivers. Running a pair in parallel at 4ohm off a modest pro audio amplifier will easily push these drivers to high levels.

IB15
Fs: 16Hz
Qms: 6.8
Vas: 439L
Cms: .45mm/N
Mms: 220g
Rms: 3.239
Xmax: 18.5mm
Xmech: 25mm
Sd: 830sqcm
Vd: 3.07L (p-p)
Qes: .78
Re: 5.5ohm
Le: .33mH
Bl:12.49
Pe: 500W
Qts: .7
1WSPL: 86dB
2.83V: 87.3dB

Physical dimensions:
Cutout hole: 14"
Outer diameter: 15.5"
Mounting Depth: 7.5"
Overall Depth: 8"
Weight: 19lbs
$150 each or 4 for $500

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DIPOLE10 (coils in series)
Fs: 25.9Hz
Qms: 11.0
Qes: 0.73
Qts: 0.68
Vas: 118 Liters
Cms: 0.7mm/N
Mms: 54.6 grams
Sd: 345 cm2
Rms: 0.81Kg/S
Bl: 12.2T/m
Re: 12.3 ohms
Z: 16ohms
Le: 0.15mH
Pe(max): 200Watts
1WSpl: 87dB
Xmax: 12mm
Really Expensive
Low Efficiency


The Lambda motor is 20 years old. A radial NdFeB motor with a much smaller rear blocking area is the current state of the art for medium displacement bass and midbass.

[LineSource]

studiotech....

XBAFFLE and EDGE freeware running the described driver T/S parameters.

The XBAFFLE graphs does not include the baffle shape or driver location, just the "dipole potential" of each driver's T/S parameters.

The EDGE models the H-baffle with floor reflections for the 15" dipole woofers and a minimal baffle "nude" 10" midrange. Simple equalization was turned on.

I have experimented with listening to unaccompanied vocals with different crossover frequencies and different speakers. These experiments gave me an understanding why "full range" is so popular ... I could hear crossovers between 100 and 1200 Hz, especially between "signficantlly" different speakers technology (cones, Qts, breakup). A soprano like Kathleen Battle sounds like two differnt people on a two way with a woofer and 900Hz waveguide. I decided that I had to build 3-way speakers, and the main reason to pay for state of the art driver technology is to put the 80-1500Hz human voice range on one midrange drive VOICE SPEAKER.

The Lambda TD10D and Tang Band W8-1808 (cut off wizzer) are pretty good dipole voice speakers. but I think a much better design is possible with a NdFeB radial motor.

(I have 0.7" wide 5.8 micron thick Al foil if you want to DIY a dipole ribbon. A study of the RAAL "flatfoil" ribbon explains how to get dynamics)

[studiotech]

Linesource, yes your line of reasoning is just what I've been working towards. Leaning towards Lambda mids and woofers with the Raal, but have MANY other mids here at the moments for listening and measuring.

Digmoda current pricing is a little higher, but not too bad for what one gets. Been working out of town since the first post so news to report.

May pull the trigger on the TD6 dipole that John has now, but might hold out for the 8" too! I am prefering larger or multiple mids. Considering an array like Legacy uses on the Whisper or Helix. Was very impressed with these @ last years RMAF and the lame AXPONA show in Jacksonville.

Greg

[LineSource]

studiotech

Have you found the perfect dipole midrange yet?

From my limited listening I find I favor 8" or 10" wide bandwidth speakers with a Qts just under 0.5. A low Mms is required to get good efficiency. I've played around with simple T/S parameter equations to see what might be possible.

I find it interesting to compare the wide bandwidth, extremely flat SPL vs. frequency curve from an 88db/watt 7" midbass ScanSpeak Illuminator with the extreme rising SPL respone from a 98db/watt pro sound Emimence 8". I'm hoping new technologies can create a 95db/watt 8" or 10" midbass with the same wide BW and flat SPL of an Illuminator.

[studiotech]

No news to report. Too much travel with work and then on vacation. Sitting in Prauge @ breakfast right now! Wonderful live music everywhere though. Just sort of drifting down the streets. Heard many church choirs yesterday. It was sublime.

Greg