Slot Resonator Build

Hey everyone, I'm a long time visitor and just finally jumped in and signed up to share a couple projects I've got planned. I'm more a musician and producer than I am studio owner, but I figured I'd take this winter as a chance to improve my setup (and hopefully save myself some money in the long run). This site has been an incredible resource, and hopefully I can give a little back while I do my best to soak up the expertise that so many here graciously give away! My control room is in the master bedroom of a rental house. I'll get some photos and diminensions ASAP. We're setup around a MCI 636 console. We're lucky enough to have a MCI JH-24 2" (that doesn't get enough love lately) and she lives in another room. The room actually sounds pretty decent and fares pretty well with a pink noise shoot. As always, room for improvement. Pretty much, I'm trying to build John's wall units as close to his designs as my feable carpentry skills will get me! Today I started on the slot absorbers. I'm building two 7' X 4' units. My plan is for them to be free standing with some anchor hooks/eye hooks and twine attaching them to the wall (just to keep them from tipping). I'm trying to keep all the treatments fairly movable as I'm am looking at moving in the next 12-18 months. Here's a couple pics after today's first trip to Lowes. I had them cut the two 4' X 8' x 3/4" (no 1" to be found) MDF boards into 8' X 8" strips. Perfectly straight and clean cuts (and no clean up!). Enough to frame out the two units plus a couple left over for the next. Tried to make notes in the descriptions but they didn't get posted. Sorry 'bout that! I made the remaining cuts to the MDF, mocked up the frame and applied a bead of construction adhesive anywhere two boards met, then 2" brads (and a pneumatc nailer) sealed the deal. I only have a circular saw, so I had to experiment with the angle of the cuts on the slats (as well as the length with those angles!). Came out pretty flush with the sides of the frame. I'll make it airtight with caulk and maybe some rubber tubing. The front of the slat braces are 3/4" from the frames front edge, sloping to 2" inside the frame (hopefully as per John's specs). After I had mocked up some slats, we flipped the frame, glued and nailed the 1/4" plywood back. Tomorrow we'll finish this one out. Not sure whether to use 703 or fluffy pink stuff. Hoping to save the 703 for the rear wall absorbers. Any suggestions? Couldn't seem to find if it really matter for these boxes. More pics soon!

Got a bit more done today in between trying to make the G5 be friends with Logic Studio! Hoping to finish these two tommorow and move on the the back wall bass panel. I used the pink stuff on these, figured I'd save the 703 for doubling up and taming the lower octaves. The insulation just barely touches the slats at their most narrow depth. I know there's some debate as to whether it should touch at all, but I'm not aiming for a specific feq, so I figured I'd leave a little damping, and I think it'll work well. I used twist wire and staples to keep the insulation in the back of the box. Next post should see these two boxes in the control room!

very nice!

Yeah, looks great!

Thanks guys! Here's a pic of one done unit (right wall). Down the road I may add some trim for aesthetics, but for the price of enough trim to finish these, a can build two bass traps! Got a bit distracted today with more Logic woes, but I'll get some pics and initial results of my little hobbit hole up ASAP. Rog

Very nice! I'll be making some of these in the next month or so too :D How did you fix the slats onto the frame to the braces? Thanks, Gareth

Gareth, I caulked (Liquid Nails, I think) the out side edges of the slats (the short edge that meets the frame wall) and used a couple 2" brads. I was worried about this, and how to make it airtight. Because the fabric (black quilters cotton) is between the slats and the bracing, I couldn't just draw a bead of caulk on the braces and nail them. I'll include a pic. Not to scale or anything. If you had the right tool (table saw?) to bevel the supports, it'd be a LOT easier. Cutting those slats one by one with beveled edges (with a circular saw) is a pain! Plus, I'm sure that the way I'm having to attach them has an affect on the freq., Q, and efficiency. But as I'm looking for broadband coverage, I didn't worry too much. The boards still resonate when tapped over a big range of frequencies (not so much as to be a problem - though I'm glad I left a little insulation touching to dampen a bit). It's pretty amazing to hear the difference in freq the same size slats cover with the other variations in place. I mean, it actually works! Gotta love physics! I'll keep looking at this http://www.avatarstudios.net/ for inspiration... BTW, I don't think I'd be doing this without that Pneumatic nailer! Rog http://www.mingofishtrap.com

Here's a couple shots of the units in the control room. The difference was really noticeable! Along with the bass trap cluster on the rear wall (just fluffy insulation in those - already had them), which I mounted about two inches off the wall, the units have done away with the hi and mid-hi flutter I had at mix position, tamed the low-mid peaks, and as you move around, the room seems to be more consistent overall. I think I may build two more, but at half the width, to cover a bit more of the side walls. As new stuff gets put in, I'll update. Rog

These look great. It makes me ask a question: If you build a bass trap (like a super chunk) - can you (or should you) cover the face of it with these wooden slats with the alternating slot widths? Is there any value in doing something like this?

BradJacob, John's design for corner traps is an airtight slot resonator with a couple layers of insulation, so I'd think if you made some super chunks inside an airtight "box" with slats on the front (leaving some air between the slats and the chunks) it would work. Though it doesn't seem like it'd be that much more effective in the lower octaves. And with so many variables, it doesn't seem like the corners would be the place to address particular freq. issues. Guess you could always just drop the super chunks into place and see if it takes care of your problems before you finish them out. rog

I figured I'd post a shot of these portable 4' X 2' slot resonators. The boxes are only 4" deep, so not meant for low absorption, but they've come in really handy for changing the sound of our little drum room. They're on a swivel (threaded rod running through the box with washers and wing-nuts on end), so they can break up flutter pretty well too. They stand about 7' high. I think I'm going to build another four that are 8" deep on stands made of angle iron (or something metal) with the small holes in it so the height could be adjusted. Also considered putting two 3'6" boxes stacked on one stand so they could be swiveled independently of one another. rog

Wow those portables look awesome! It would be interesting to hear a quick recording with them in and out of the room to see how they change the sound. Any chance of one? :P :wink: Also how big is your drum room, as mine will be pretty small too so i've been considering what I'm going to do in there. Those portable slats look as though they might be a great idea :D Gareth

The design on those is great! It does look like they would be better however at reflection rather than absorption. Keep up the good work, you are flooding us with great ideas!

what happens to the sound if you tip them back at the top about 6"?

Thanks for the encouraging words guys! Basically, my drum room is fairly small, about 18' X 12' X 8' 6" high. It's a little room within a room inside a garage. I went way overboard with high end absorption when we first put it in. Aside from an extremely dry recording (which I could deal with), the main problem to me is that it hasn't been very fun to make music in. Just way too dead in the highs and not well treated in the lows/mids. I find that drummers play louder when there's no reflection, which compounds the problem. It's a rental, too, which means I'm gonna eventually have to rip it all out. If it wasn't, I probably would have just built every wall into a huge slot resonator with no parallel walls. But that will have to wait, so I figured I'd rip a lot of the carpet and Auralex out and deal with the flutter, etc. with this kind of solution for now. I'm really happy with the first tests. I'll post examples as soon as I can. rog

Hello every body I can not find any answer for this q. COuld you help me? ohn's diagram shows diferent pieces of timber on the face of the wall of alternating widths (100mm, 75mm, and 50mm). i'm curious as to what pattern i should alternate them (i presume it would be 50, 75, 100, 75, 50, 75, 100,75, 50 etc.) i'd also like to know in what pattern i should i place the gaps between the timber (the three sizes john has recommended are 6mm,, and 12mm). should i place the larger gaps next to the narrow pieces of timber, or next to the wider ones? Thanks!!