DIY Overhead Atmos Support (Volt 6) + SI HT18 V2 Nearfield Subwoofer Build - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 2 Old 11-15-2017, 05:14 PM - Thread Starter
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DIY Overhead Atmos Support (Volt 6) + SI HT18 V2 Nearfield Subwoofer Build

For roughly a year I've simply ran two pairs of KEF 4" coaxials as my overheads for Dolby Atmos/DTS:X needs. However it was time to upgrade to the Volt-6 kits, one of which was already built as I had ran them as my rear-back surrounds which hung on the back wall. I finally got around to having built a second pair of Volt-10 LX earlier in the year to have every surround ground level which had to be one of the best upgrades I've done to my system, position wise.

So in with the mounting solution for the Volt-6! The KEF speakers I had screws into the ceiling joists, which limited my placement options to fixed locations that were 24" center to center. I needed a way to add more flexibility to my setup so I could fine tune or even reconfigure their positions in the future.

First, I wish to thank @asarose247 for the inspiration of his setup that utilizes unistrut channel. I had then begun to work with some ideas on how I was going to do this, and what took the longest on getting this done was figuring out the most optimal choices on brackets. My ceiling isn't as optimal in my space as I'd wish it to be, but I've settled with 13/16th inch tall strut channel, solid back so I could drill the holes to the size I needed for the 1/4" lag bolts I used for fastening them to my joists.

I had bought three 10ft long pieces of this channel. Two that are for the main mounting points on each side. Then one to use for the shorter pieces I used for the cross pieces. To make them where paint would stick well, I got some vinegar and some scotch-brite pads. Which I used to clean them up and get every bit I could so my matt black spray paint will stick.



Worked rather well overall, just had to make sure you get it quite thoroughly or else paint can flake off in missed spots. Plus having a couple of good coats of paint helps.

So the next step was the brackets, and accessories for the unistrut. I found some accessories I thought would be pretty sweet...



.... but the holes are way to big! Especially since I am using 1/4-20" bolts for everything!

Fortunately we have a machine shop in the area, who I know pretty well too. Thus the numbers written on those plates came from, to make custom ones to make this work.

They were pretty quick with the turn out and got them done the next day, so I test fitted it with some short pieces of strut channel.



Looking pretty good! I had it setup where I would need to drill and tap a hole for this, for another set of brackets I had them make up for me, for the Volt-6 speakers.



With that, getting the channel up with more test fitting!




Onward to painted brackets!




Then finally, the hung Volt-6 speakers!






Wiring wasn't completed at the time of these pictures, and I'm still currently using the other wires I had for the previous overheads, but I plan to re-do that when I work on the whole system wiring in the near future.

I do feel the Volt-6 made a really nice improvement for the overheads, they've really always been one of my favorites! I want to thank @Erich H for offering those up on DIYSoundgroup.


I've also recently built a nearfield subwoofer for my system, which is still in dire need of proper calibration for my system... but regardless, this is my very first subwoofer enclosure I've built from scratch, and that wasn't a flat pack. I want to thank @Gorilla83 for providing the plans, as this was one of his designs! Unfortunately I don't have a CNC machine like he does so I had to manage with what I had.



I drew out the measurements and where I needed to cut for the cross bracing, which I had to use my jigsaw for it.




Then after using my router jig, I've got the baffles installed.




Then after using the router trimming bits, vinyl spackle, sander, and duratex, I filled the enclosure with a few pillows and installed the drivers. Here it sits behind my sofa.



Definitely a good learning curve for me, and it really makes me appreciate the work and effort I see others put into their subwoofer boxes here on the forums. Having the appropriate tools certainly pays off and would pay off if I had a bit more on hand as well.


So in the end, here's what things look like as of now with out any form of calibration. I had this running of Subwoofer 2 output so it's on the closet setting, but I notice with the nearfield alone, there's a pretty big null around 25Hz. Then likely timing issues when actually running at the same time with the front subwoofers.



With that said though, should I concern myself with the null, or just focus on trying to get the delay settings correct? I'm planning to run it off the DCX2496 that the rest of the subwoofers are running on. I don't exactly know how to use R.E.W. to measure for delay though.
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post #2 of 2 Old 11-19-2017, 04:37 PM - Thread Starter
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So I've begun to perform some work with the DCX2496 on integrating the nearfield into the system. Deciding to try to follow @mtg90 's well written guide. https://www.avsforum.com/forum/155-di...ow-thread.html

However I feel that I'm at a loss in the delay department. To my understanding nearfield subwoofers need delay added to align with the rest of the subwoofers infront of the room, correct?

For some weird reason, any delay I add, worsens the response. I've tried anywhere between 5ms to 10ms, it's showing to be at it's best with delay settings off.

Though, for the time being, I decided to play with some EQ settings in the meantime, to try to flatten the response a bit.



Input A's EQ settings as follows:
All -10dB @ 35Hz Q2.5 - +1.5dB at 20Hz Type LP 12dB mode, and -10dB @ 35Hz with Q2.5
EQ Test 2 - +1.5dB at 20Hz Type LP 12dB mode, -3.5dB @ 28Hz with Q3.2, and -3.5dB @ 40Hz with Q3.2
EQ Test 3 - Same as Test 2, but with an additional EQ of +5.0dB @ 71Hz with Q5.0

Probably too much boost on Test 3 at 71Hz, since I likely should keep that portion more minimal.


Should I try to aim for a flatter response roughly as shown? I still want to keep the subwoofer system hot, but I also want a more even response. Next few weeks, I will be adding a couple more dual opposed subwoofer cabinets using 21" drivers, so I'd like to get the hang of getting things under control.
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