InDIYana 2022; "Missing Link" theme announcement....

[Billet]

I'm also hoping one of my friends comes this year and brings the Misfits, which I helped build. They are an odd combo of a sealed TL with a 5" woofer and a 6.5" open baffle tweeter. (ES140 and a PS180)

[Wolf]

He sent a request to the event addy, I have him on the list!

[Wolf]

I thought about bringing the Zingers again. That cool?
Wolf

[Billet]

It's cool with me, I'd like to hear them again. I'm bringing the B9's and it will be like 2019 all over again...

[Billet]

The Zingers are always good!

[jhollander]

I'd say those are a MWAF winner for sure

You know the mini LX521's haven't appeared at MWAF and they have a better story. There was talk about one entry per person so these may not go. At least these are buildable

[ugly woofer]

By buildable, do you mean that all the drivers are available?

[jhollander]

I think it's a matter of perspective. The mini LX521 is not really buildable because there's no drawing for the shape of the top portion of the LX521, but the LCR mains are a simple box. Not saying that some talented people couldn't build it, but in general I wouldn't place it in the buildable category. …similar to some other builders designs.

[Wolf]

Yeah, like nobody will build my Trichotomy, Cecropia Supreme, or my in progress Tandems that even I am having difficulties with. There are some people with ingenuity to do so for more difficult constructions, but you don't see it much.

[4thtry]

Congrats to Ben & Chuck on the Lifetime Achievement Award for their contributions to DIY audio!! Well deserved!

[4thtry]

Congrats to E.Q. from Singapore, winner of the missing link xover design competition (entry #2). He completed his xover in the adjoining room just moments before the competition began. Special mention goes to Meredith C., as some of the parts from his 4 way OB speaker project were used by E.Q. to complete the winning xovers.

[Paul K.]

I really enjoyed the event and thought that the awards given to Chuck and Ben were well deserved. I hadn't been to an event since 2019 and had a great time seeing and talking to familiar faces while meeting a few people new to me.
Paul

[Wolf]

Thanks, guys! I was really shocked, and it took about 45 minutes before I was myself again.

Wolf

[DaveFred]

How "different" were the various XO's in design and sound?

(I know, very broad question)

[PWR RYD]

I could hear differing levels of baffle step compensation and I definitely could hear if the tweeter's natural resonance was tamed or not (or maybe it was the woofer's breakup not being notched enough). The opera singer's voice got nasty on some entries. None of them were awful but there were audible differences for sure.

[jhollander]

I'll add that a few closely split the room. Process was 3 to 4 x-os each played a 5 minute demo track, then vote for your favorite by a show of hands. Of the three finalists 2 were voiced. I thought it was interesting how everyone had different things they were listening for and that the back of the room could hear more of the breakup.

[mobius]

I really hope you guys are going to post the winning xo schematic and better yet, the next couple of best ones too. Lots of valuable info there for those trying to learn the hobby.

[wogg]

I really hope you guys are going to post the winning xo schematic and better yet, the next couple of best ones too. Lots of valuable info there for those trying to learn the hobby.

That's a great idea! I'll have to post my design and reasoning behind it when I get a chance. Didn't win.. but was in one of the "split the room" votes so I'll take it!

"Hoping to finish in the top 10" - Billet

[Rory Buszka]

There were some requests for additional information about my DIY "LRAD" portable acoustic hailing demonstration, and the speaker components used for the "acoustic emitter" - the speaker head.

The drivers used were PRV Audio D4400Ph-Nd phenolic-diaphram neodymium drivers, with a combined weight of 35 lbs of driver in the speaker, plus about 10 more pounds of MDF and hardware. They are mounted to horns from "Blast King", a car audio company with a cheeky name, but they were the right size and the right flare rate, and they had a very solid thick wall construction. The D4400Ph-Nd is about 6" in outer diameter, and they have a 4" diaphragm with a 4" voice coil, so they are the most monstrous midrange-oriented compression driver I could use at a reasonable price to keep the project feasible. (BMS has a dual-diaphragm midrange compression driver but that would be unreasonably expensive.) The emitter was positioned a little less than 6' off the ground using a pro-audio tripod speaker stand.

Peak sensitivity of the driver is 113dB 2.83V/1m, and the four drivers operate as a coherent 'phased array' summing to provide a voltage sensitivity of 125 dB @ 2.83V/1m, with the impedance dropping to 2 ohms (all four drivers are in parallel). This is no problem for the amp used, which is an auto sound amp with an internal step-up power supply, designed to draw power from a 12V battery. The amp I used for the demonstration was a SounDigital Nano 250.2 supplying 125W into the 2-ohm load, but the plan for future demos is to use a Taramps HD3000 2-ohm variant to supply up to 3kW peak into 2 ohms.

Frequency response is from 500 Hz at -10dB to 7.5kHz at -10dB (full power operating range 400-8,000 Hz should be no problem), and peak SPL is at 4.5kHz, with smooth-ish response between 1kHz and 5kHz (no big peaks).

With the amp I used, peak SPL at 4.5kHz/1m should have been around 145 dB, and SPL at the 500' distance of the listening position should have peaked around 100 dB, but for various reasons (including atmospheric loss, windage, ground reflections, power compression, throat distortion, or the lower crest factor of speech compared to tone signals) I suspect I wasn't achieving that level, at least not continuously. There is more testing to be done. With the bigger amp, it should be possible to reach continuous on-axis levels of 154 dB at 1m, and peaks of 158 dB; that's pretty lofty so I'll need to figure out a way to validate that. The guidance from FEMA for designing outdoor warning siren systems uses a -10dB per distance doubled model instead of -6dB for a typical point source, so they are factoring in more losses. Even so, all reports during the demo confirmed there was no lack of volume.

Thanks for indulging me with the chance to demonstrate this project publicly. There's nothing really patentable here; the design approach is to implement a modular construction with a phased array of 'cells' that provide good efficiency in converting electrical power to acoustic power. They can then be configured in any manner needed to optimize dispersion and suit the application, such as a panel array (imagine 2x4 or 3x3 units in a grid), a circular array of 12 drivers, a hexagonally-packed array on a flat surface, or a ring array (annular array) where very narrow dispersion is needed from a minimum number of sources.

JR's wife took a video: https://www.youtube.com/watch?v=OhusYx4Dv3Q

[tktran]

Congrats Ben & Chuck!

Sounds like you guys had a great time. What a great little community for our niche hobby.