The Defiants - InDIYana 2019 Build

[KEtheredge87]

Thanks again jhollander , rpb , PWR RYD , and wogg. Seems like I left the proverbial corner I put myself in, but I forgot to take off the dunce cap

That kind of silliness will bug me, so I'll fix my mistakes later tonight/tomorrow and repost a model. One that will hopefully match my measurements better!

[scottvalentin]

Great process and thanks for sharing. jhollander and rpb and PWR RYD great input!

Always learn a lot when you guys are helping others!

[KEtheredge87]

Hey Everyone - it's been a few days so its time for another update. I had promised to post a new model result after taking more measurements and correctly processing my woofer nearfield / farfield and tweeter farfield with the Jeff and Charlie response blender program. I did give this another go... or two or three... but I still could not get things to match up with reality, so I don't know what I've done funny with that side of things. In the interest of time, I moved on to the final stretch of the project.

Armed with OmniMic measurements that showed a good looking response curve and reverse null, and my listening interpretations of the design as-assembled, I pushed forward with orders for final XO components. I needed some 2.0 mH solid core inductors for lower DCR, some proper 20uF capacitors for the LF section, and some 15ohm resistors to triple-up in parallel (5 ohm composite) for power handling at high volumes on the HF section. I have a rough layout put together on the 3" x 5" perforated board that I selected and epoxied into the cabinet base way back on post #2, and I'm going to go vertical with the capacitors to save some real-estate. I am also glad I was able to swap a 0.15mH x 14 AWG inductor for a much smaller 18AWG version without any appreciable drop in signal, as that saved a lot of weight / a little space too.

Tonight I'll start assembly of the XO modules and test the assembled version outside the cabinet (no more gator clips!)

[KEtheredge87]

Bonus post for today - Speaker Grilles!

Normally - I hate speaker grilles. They hide the pretty drivers, generally do *something* however small to the sound we hear since they are in the way, and they're one more thing to plan for and create as part of the design.

However, this time... with that delicate fabric dome on the RST28F sitting like a bullseye in the middle of the Visaton waveguide, I decided it was worth the effort and "insurance factor" to make it work. One day I will have kids... so grilles will be a part of life. Well... grilles and a giant safety fence between the tiny humans and the artfully designed DIY masterpieces! I'll sit back and turn the volume up and rationalize my words thinking, "Nah... that wasn't super smug of me to call my speakers DIY masterpieces on the forums so many years ago... I'm a humble guy... yeah...."

But I digress... Let's talk about how I made grilles!

Step 1) Design a pattern - I did this by copying the edge lines on my baffles in Fusion360 and printing it out as a template on 11" x 17" paper. Since I went this route, I also gave myself a center mark for holes cut with the router jig, and some guide lines for sanding to-the-line in the area in-between holes. This paper template was adhered to some 3/4" MDF using 3M Super77 spray adhesive, which worked great!

Step 2) Cut the actual grille frames - I went with 1/2" baltic birch plywood for the frames because I had some extra laying around, and because I wanted the strength. There are two thinner sections in my grilles, and I wasn't sure if MDF would hold up if someone bent them just the right way to remove the grilles from the cabinet front (remember... I put some neodymium grille magnets in the cabinets to hold these). I rough cut the insides of the pieces with a jigsaw, the outside of the pieces with the bandsaw, then secured both grille blanks to the template with double sided tape. Kind of like a grille sandwich. And now Im hungry!

Step 3) Flush cut, machine, and magnets - I used a 1/2" spiral upcut flush trim bit in my router table to remove the excess plywood and match my template shape, then I used a chamfer bit to put a 3/8" 45 deg chamfer on the outward facing edges. This made the grilles blend in with the facet-aesthetic on the cabinets pretty well in my opinion. The last part here was embedding more magnets so the grilles would be attracted to the cabinet baffles. It's important to observe polarity on these magnets so your grille actually attracts to instead of repels from the cabinet!

Step 4) Paint it black - Since I knew I had some black "Mellowtone" speaker cloth from PE to use on this project, I used some Krylon matte black spraypaint to coat the outside of these grille frames. I didn't want the bare wood to be visible after I applied the grille cloth, which is supposed to be acoustically transparent. That also means you can see through it if you're close enough, and that bare wood would definitelly show through enough to bother me.

Step 5) Apply fabric to the front - Again using 3M Super77 spray adhesive, I put a good layer on the outside / front facing surfaces of the grille frames, then pressed them face down on some stretched out grille cloth. This helped set the initial tack, so I could flip it over and start pulling the fabric into the corners and curves. This wasn't too difficult to do by hand, but I did use a roller to make sure everything was super smooth and adhered after I got it placed well.

Step 6) Fold fabric around back and trim - Using one last coat of 3M Super77 with a scrap of HDF to shield most of the grille fabric on the interior, I got the backside of the grille sticky and ready to accept the grille fabric. When tacky, I folded the fabric around the backside of the grilles, which required some 45 degree cuts and seam joining. This process isn't too bad and is decently easy once you get the hang of it. After the fabric was covering all the surfaces of the grille I took an olfa razer knife and trimmed the fabric on the inside face of the interior, where the speaker cones will be. The end result is a smooth cover for the speakers that looks seamless from the front!

I still have a little bit of bling to apply to these grilles and speaker cabinets in general... pictures of that will come later. Hope that helped!

[KEtheredge87]

A few more pictures...

[KEtheredge87]

Whew! After a whirlwind weekend and a great time at InDIYana 2019, it's time to update you all on the Defiants. Yes, I did finish them on-time, and yes, my crossover was pretty darn good for just 5 parts! A big thank you goes to jhollander for some help troubleshooting my XO modeling issues via email. Turns out my issue was a mislabeled tweeter ZMA file... It was right under my nose every time I opened up PCD and scrolled by the tweeter impedance plot. For future reference, tweeters are not supposed to have a double peak and tuning frequency of 38Hz! After loading a correct ZMA file all the issues went away and I had good agreement with my measurements. Speaking of which... here's some pictures of my final XO design for the competition, some measurements, and the Front Baffle reveal! Much more detail on all these topics are in my masters thesi... I mean writeup! I may have gone a bit overboard, but I do it for you guys!

[KEtheredge87]

As-expected, the PETT forum software won't allow me to post my full write-up directly because the filesize is over 2MB. Instead, I have a google drive link where you all can view my writeup by clicking below. You'll have to trust that I'm not going to rick-roll you ;)

The Defiants - InDIYana 2019 Bare Minimum Competition - Final Writeup

So what's next from here? I will be doing some vertical off-axis measurements to accompany the horizontal off-axis measurements that I detail in the report. I will also be doing some A-B testing with an additional 1.5ohm resistor after the 20uF capacitor in the LF circuit to control the woofer knee. I tend to like relaxed midranges, and the current 5 part XO measures much more flat than relaxed. I don't find the current XO objectionable at all with 5 parts... I just think it might be that much better with a 6th component. Time will tell.

Otherwise, these bad boys will be going to Midwest Audio Fest in July! I hope to see you guys there!

Thank you so much for following along with my build and learning with me. The interactions are what make the build logs all worth it.

- Keith

[Drjay]

Your PDF write-up is top notch as were the Defiants in real life. Thanks for posting it all.

[KEtheredge87]

Your PDF write-up is top notch as were the Defiants in real life. Thanks for posting it all.

Thanks Jay! I did go full-on Master's Thesis on that writeup More of a reflex than anything... it's amazing how that kind of writing style sticks with you long after the document gets published!

[OldBeginner]

I would say you did not go overboard at all! These kinds of threads are fascinating and watching you work through this process is both entertaining and informative. i don't know if I will ever try to design anything of my own, but seeing others work through the process is a big part of what makes this forum a place I come back to.

Also - those look really really good. My hat is off to your woodwork.

[scottvalentin]

DID NOT SEE THE BLUE SNAKESKIN COMING!
Nice job Keith and hope to hear how you made out in the competition. Those look amazing and unique, and obviously a meticulously designed project.

[KEtheredge87]

DID NOT SEE THE BLUE SNAKESKIN COMING!
Nice job Keith and hope to hear how you made out in the competition. Those look amazing and unique, and obviously a meticulously designed project.

Thanks Scott! I actually got knocked out in the first round by ugly woofer and his very well designed honeycombs! He used the aluminum dome RST28 tweeter to great effect. I think I took 14 votes to his 24 votes! At the end of the day I was still smiling as I heard my speakers in the room, so I consider that a win. I'm looking forward to a rematch at MWAF

[jhollander]

Keith, nice write up on the Tolex and write up in general. Not likely you are going to be in the same category as Nick at MWAF unless Nick changes the woofer?

[wogg]

Are you going for the under $200 or all Dayton category Keith? Mine will be back in the under $200.

I think it will come down to personal preference and the audition tracks... that goes for all of the expected repeats I heard over the weekend. They're all damn good!

[KEtheredge87]

Are you going for the under $200 or all Dayton category Keith? Mine will be back in the under $200.

I think it will come down to personal preference and the audition tracks... that goes for all of the expected repeats I heard over the weekend. They're all damn good!

Wogg... I can't quite decide what category I should enter into. I handily fall into the under $200 category with only $87 in drivers ($100 if you count the waveguide). The All-Dayton category could in theory have someone showing up with a giant WMTMW with 8's and 10's and whatnot, which would be an odd comparison to a 2-way bookshelf design. I know it's about sound quality... but I tend to think people listen to music with their eyes more than their ears sometimes.