Sonolok Acoustic Panels for the Living Room Wall

Sonolok acoustic panels come in boxes of four. 

The TV in my living room hangs on a wall that's about 3.3m (11') high x 6.7m (22') wide. That wall has had TVs and other things hung on it by previous owners of my condo, all of whom did less than professional repairs to the drywall. It looks awful. It also happens that the opposite side of that wall is my neighbor's bedroom, and it happens that my stereo speakers are positioned along that wall on either side of the TV with their rear radiation bouncing off and going through the wall.

 

This is what I started with. Is it really that hard to patch a hole in the drywall? And whose idea was it to just paint over it?

I've have been thinking about what to do about it for a couple years. I wanted something that would look nice and not seem out of place in the room/building. I considered just repairing the wall and painting it, or hanging wall paper or a wall paper mural. 

On my recent semiannual trip to Costco I saw something called Sonolok acoustic panels on sale for $30 for a box of four panels (they go for $90 per box on the manufacturer's web site and $40 per box at Wayfair). I looked them up and watched some YouTube videos about installing them and decided this was the way to go. The panels will theoretically reduce sound transmission through the wall, though the manufacturer provides no specs to that effect, and will provide some absorption and diffusion of the rear radiation from my speakers, all while looking pretty good and fitting with the look of the room/building. The panels get good reviews of their acoustic properties on amateur audio forums.

Each Sonolok panel consists of a dense synthetic felt pad 600 mm square x 10 mm thick with 27 mm wide x 13mm thick walnut veneered (really?) MDF strips stapled to it. The strips are spaced 13 mm apart. The wood strips are offset on the felt so that two edges of each panel will neatly overlap adjacent panels. Each box of four panels comes with two right side and two left side end-pieces to neatly finish the look of the wall. There are also black drywall screws and a bunch of round, black, felt stickers to hide the heads of the screws. 

My building was converted to condos about 20 years ago and uses steel studs, spaced 24" apart, covered with 5/8" drywall on both sides. I checked building codes to see what the allowable lateral loading on the studs would be (you can't just start putting heavy stuff on the walls without regard to the loading capacity!). This wall, like all the walls in my condo, are non load bearing (the rafters, posts, and beams carry all the load). I found that acceptable loading on non load bearing light gauge steel studs used in my walls was 10lbs/sqft. The wall is approximately 12' high x 22' wide, so 264 sqft. The 5/8" dry wall on both sides of the studs loads it to 4.4 lbs/sqft. The Sonolok panels add about 1.65 lbs/sqft, so the load on the studs will be a bit over 6 lbs/sqft, well within the allowable 10 lbs/sqft limit.  

Front side of one of a Sonolok panel. The felt backing is 600mm x 600mm (NOT 2'x2' as at least one Youtuber would have you believe). The wood slats are 587mm long x 27mm wide x 12mm thick, and are spaced 13mm apart. Don't worry, the dark area is the shadow of my head when I took the picture. The color of the wood slats is perfectly uniform.

The back of a Sonolok panel. The felt pad is 600 x 600 x about 10mm thick. The wood slats are stapled to the felt. Note: at least one YouTube reviewers says the panels are 2' square. NO they are NOT! 600mm is not 2'.

One of the panels with the right and left end pieces. 

When you put the end pieces in place, their slats are spaced the same as the others for a very neat look.

When the panels are installed, there will be neat, uniform horizontal gaps between the wood slats. This eliminates unsightly mismatches in the slat positions if the panels/slats aren't placed perfectly. One YouTube installer actually cut the felt at the top of the panels off so the slats would contact each other. Then he suggested hiding the resulting mismatches by using wood putty and sanding. That's insane!

The recommended mounting method is to put construction adhesive on the back sides of the panels then screw them to the wall to hold them while the glue sets up. I had a different idea. I decided to mount the panels on furring strips that would hold them away from the wall, allowing things like network, power, and speaker cables to be hidden behind the panels.

This is the wall that will be covered with the Sonolok panels. The plan is to start the panels at the top of the baseboard and go up from there. There are a couple electrical outlets and a TV mount that will have to be accommodated. Note: the light spots are reflections of the sun from the disco mushroom sitting in the window.

At the top of the wall there are unevenly positioned rafters. The top edge of the Sonolok panels  get close but won't require any trimming around the rafters.

As usual, I started the project by making a CAD model of the wall and the Sonolok panels so I could figure out the layout before starting the installation. 

This is what the wall will look like when it's done. The green thing is the wood structural post that stands forward of the wall by about 200mm. This image doesn't show the TV wall mount that I'll have to make cutouts for. There are 5 vertical x 11 horizontal Sonolok panels here, with right and left end pieces. The wall is a a few mm wider than the panels and end-pieces so I'll have to finish the right side with a custom end pieces to hide the furring strips.

Tools

 

Besides the usual electric drill/screwdriver and a tape measure, I used a couple special tools for this job:

Laser "tape" measure. IRIC it was about $30 a few years ago when I bought it. I have checked it against a couple different tape measures and found it to be very accurate.

3 axis laser level I bought from Temu for about $40. It projects horizontal and vertical lines so it can be used to check the squareness of walls, the level of floors, and to follow studs in the wall once they have been located using a magnet. I verified it's accuracy by marking a level line (as reported the this level) on the wall then rotating the laser level 180 degrees. The line remained in the same position, so I could trust the accuracy of this unit.

A razor knife with a fresh blade cuts the felt very neatly and I used a pull-saw to cut furring strips and most of the Sonolok wood slats. 

I added additional staples to the Sonolok slats to ensure that every piece would have at least two staples holding it to the felt backing before I sawed through the slats. 

Special considerations

I was planning to use the baseboard as the guide for placing the panels, but the laser level revealed that the baseboard that follows the floor is neither flat nor level. 

The green laser line is aligned to the baseboard at about the middle of the wall...

Left end of the wall at floor level. 

Level at the right end of the wall. The floor at the left side of the wall is about 30mm higher than the floor at the right side of the wall.

The left end-piece and panel had to be cut to fit around the bricks in the upper left corner of the wall.

There are three outlet boxes that had to be allowed for and a wall-mount for the TV. 

Decisions, decisions...

The original plan was to leave the baseboard in place and follow its top edge with the bottom of the first row of Sonolok panels. That wouldn't work because, like the floor, the baseboard's top surface is neither flat nor level. This install was over a wood floor that occasionally gets vacuumed and wet-mopped, so I couldn't just remove the baseboard and run the panels down to the floor because the finish on the MDF slats would not hold up against the vacuum cleaner nozzle or a wet mop. The baseboard hides gaps between the drywall and the floor, and protects the soft drywall from things like vacuum cleaner nozzles and wet mops, so it needed to be left in place.

I settled on mounting the Sonolok panels on furring strips. The furring strips are thicker than the baseboard, so the Sonolok panels overlap the baseboard. I just installed the bottom edge of the Sonolok panels along a level line overlapping the baseboard a little. That allows the panels to be high enough to protect them from the vacuum cleaner and mop. I didn't have to trim the bottom edge of the panels to fit the unflat floor or the baseboard.

This is how the Sonolok panels, mounted on the furring strips, overhang the baseboard. The gap between the Sonolok panel and the baseboard, and a few horizontal gaps between the furring strips allows me to bring speaker cables out from behind the panels. 

Preparations

I put masking tape on the floor at the baseboard and the right corner of the wall and painted the baseboard and right edge of the wall black. I also painted the left edge of the wall black right up to the bricks. Then the power outlet plates and TV mount were removed and the areas around them painted black, as well as the left and right edges of the wall.

Black paint on baseboard, surrounding power outlet, and on the right edge of the wall.

Black paint around power and CATV outlet boxes, TV mount, and baseboard. Note the vertical lines marking locations of studs. I replaced the original white outlets and cover plates with black ones.

I used a magnet to locate the studs (it sticks where there are screw heads holding the drywall to the studs) and drew vertical lines on the wall over the studs, using the laser level as a guide. I added horizontal lines on the wall to indicate where to mount the furring strips. The laser level makes all this very easy to do.

Installation

The next step was to mount the furring strips. I used 1x2" (actual measure 0.75 x 1.5"- why do they do that?) and 1 x 4" (actual measure 0.75 x 3.5") strips that I screwed to the studs using drywall screws intended for use with thin gauge steel studs. I left some gaps between the ends of the furring strips to allow for vertical cable runs in strategic places (close to the speaker locations and power outlets). Blue painter's tape on the baseboard marks the locations of the gaps in the furring strips so speaker cables can be brought out from the wall.

Wherever the ends of the furring strips were going to be visible I painted them black.

This is the layout of the furring strips with some of the Sonolok panels shown so you can see how they attach. The Sonolok panels are screwed to the furring strips without any glue so they can be removed to run cables as needed. The left end-pieces are glued to the furring strips and the ones on the right are screwed down.

I determined where the left edge of the panels would be, and placed the left edge piece and 11 of the panels and a right side end piece along the wall to precisely locate the right edge of the installation about 30mm from the edge of the wall on the right side. 

With all the prep and painting, it took two days work to get the first two rows of panels installed. They were the worst part of the job because they were closest to the floor and required a lot of bending over and sitting on the floor to work. They also involved making cut-outs for the power outlets and TV mount and that took extra time.

Installing the panels. I left horizontal gaps between the furring strips to allow power and CATV cables to go to the TV behind the panels. I considered lowering the TV enough to cover the outlets but decided against it as I need access to the power outlet for vacuuming, etc.

The first two rows almost complete. The left end-pieces are glued and the right end-pieces are screwed to the furring strips.

I used the green 09laser level to ensure the panels were aligned properly before screwing them down on the furring strips. 

I installed the panels using seven screws each- 3 at the top and bottom edges and one in the center. 

Cutouts

The positions of the cutouts were determined as I installed the panels. I started on the bottom row, placing the panels from the left edge and working toward the right edge. When I encountered a power outlet, I laid out its location on the panels using blue painter's tape, then used a framer's square to draw the cutting lines on the tape (sorry, I didn't take any pictures). In places where cutting the slat would result in a piece of the slat being held by a single staple, I added staples to stabilize the positions of those slats (example- the short slats above the TV cutout) before cutting the slats.

At some cutout locations, and at the far right edge of the installation, when viewed from the side, the ends of the furring strips were visible. I painted those black before installing the panels.

Problems

When I bought the furring strips I selected straight, untwisted boards. By the time I got to putting up the third row of panels, the 1x2s that were sitting on the floor in my living room for two days warped so badly I couldn't use them. A couple of the 1x4s also warped to unusable condition. I was able to cut them into shorter pieces, leaving out the twisted parts, and got them to work OK, but next time (hah!) I'll invest in better quality wood. For this application, it would actually be better to use strips of MDF or even plastic because it won't warp. 

The top left side panel had to be trimmed to fit around the bricks up near the ceiling. The slats are held on the felt with staples, and are made of MDF, so it's impractical to try to trim the panel at the shallow angle that would be required to follow the outline of the bricks exactly. I painted 50mm or so of the wall black, up to the bricks, and cut the left end-piece and the panel squarely to fit. Then I marked and cut the two left-most slats and felt on the panel to lengths that would fit under the overhanging bricks. I think it came out pretty good. 

The upper left corner panel was cut to fit around the bricks. First I measured and cut the left end piece, the I measured from the wood on the lower panel up to the bricks following the edge of the wood on the lower panel and trimmed the two left-most slats and felt on the upper panel to fit.

I wasn't sure how I was going to close the edge of the panels at the right side of the wall. Then I looked at the many extra left end-pieces I had and found that the wood strips are just the right width to close off the opening created by the furring strips. I removed the wood slats from the felt and glued them to the right side end-pieces and it looks very professionally finished. If I ever need to run cables through the right side I can remove one of the right end-piece plus slat, cut it open enough to run cables and then put it back. Or just make a new one with some of the many extra end-pieces that were left over from this installation.

Detail of one of the right edge finishing pieces. I removed the slat from a left end-piece and hot melt glued it to the felt on a right end-piece using a simple jig to keep them aligned. The right end-piece with the left end-piece slat attached is just held in place with screws so I can remove it easily to run more cables if I ever need to. Note: I painted the wall and the end of the furring strip black, but didn't really need to.

Jig used to hot-melt glue the left end-piece slat to the right end-piece felt. I used spring clamps to hold the right end-piece against a board, taped off the slat, then applied glue to the felt. Masking tape prevented the glue from going to the wrong places. I set the slat (removed from its felt) from a left end-piece down on the glue.

Installing cables

I prepped a set of 12 gauge speaker cables (I bought a 250 ft spool of 12 gauge speaker cable via Craig's List for $15!) for this installation. I hung the cables using some thin plastic held in place with thumb tacks. The hangers are only there to keep the cables from getting in the way when installing the acoustic panels. I also ran a piece of black network cable to the left side of the wall where the WiFi router will be placed.

Cable hangers made from thin plastic strips tacked to the wall.

I bought a power-strip/surge protector with a flat, rotating plug so that I could route the power cable up the wall under the Sonolok panels. The end with the sockets will be installed on the wall behind the TV. I will use it to power the TV, Shield Pro, and Bluetooth transmitter.

Power outlet under the TV with flat plug that rotates so the cable can go straight up under the Sonolok panels. The other cables are HDMI and optical fiber that go from the TV to the amplifier.

 

Finally

 

It took about 4 days to hang all the furring strips, run the cables, and trim and mount the Sonolok panels. I used 14 boxes of the panels at $30 each, and spent $40 on the laser level, and another $50 or so on furring strips and screws, and maybe $15 for replacement power outlets and face plates, for a total cost of about $500 to cover this 3m x 6.6m (~10'x22') wall.

I don't yet know if the Sonolok panels reduce the sound transmission through the wall a meaningful amount. They will certainly help at least a little. I'll have to ask my neighbor if he notices any difference.

The newly paneled wall is on the west side of the room. The east side wall is mostly very large windows, with heavy velvet curtains that can open and close, and is very reflective for sound with the curtains open and very dead when the curtains are closed. With the curtains open, the stereo image from my speakers seems to be a bit more sharply focused than before the wall was paneled, but that may be because I'm paying more attention to it. With the curtains closed the sound seems less satisfactory, as if the room is just too "dead". 

Living room with Sonolok paneled wall. Windows on the left are the east side of the room, Sonolok wall is on the west side.

This is what it looks like with the curtains open during the day.

 

 

Update on Arrakis 3.1- a New Mode of Operation?

Arrakis 3.1 has been working well after I sorted out some issues with the mechanism and the electronics. It is fast and quiet and not too ugly for the living room. I did run into one problem. I used 2040 V-slot material for the sandbox frame which put the glass just 28 mm over the sand. When the ball goes fast it kicks up sand and some of it ends up stuck to the bottom side of the glass. That means I have to clean it more often than I like, and the glass is heavy, so it a bit troublesome to clean it.

There are a couple ways to solve the problem. I can run the table slow, so the ball doesn't kick up the sand, but that's no fun. Or I can make a sandbox that will hold the glass a little higher off the sand. I ordered some 2060 t-slot to replace the old 2040 sandbox frame. Now the glass is 48 mm above the sand so there's much less of a problem of the sand sticking to the glass. I also printed some TPU end caps for the 2060 v-slot that work better than the hard plastic caps I had purchased for the 2040 v-slot that liked to fall out every time I looked at the table sideways.

2060 v-slot cut end. I cut the piece 3mm short at each end to allow room for the printed TPU end caps.

The 2060 end cap, printed in black TPU on UMMD. The crush ribs ensure a tight fit into the 2060 v-slot sandbox frame.

End cap in place at the corner of the sandbox frame. Unlike the crummy plastic parts I bought, these TPU parts don't fall out easily.

I had previously used a couple cheap vacuum handles to move the glass in Arrakis 2.0. They were supposed to be used as handles for old and infirm people to use in a shower/bath situation. While I was moving the glass one of them let go and the glass fell and shattered and I had to replace it at great expense.

Cheapo vacuum handles on the Arrakis 2.0 glass that failed. DON'T USE THESE!

Vacuum handle stuck to the glass. USE THESE!

The glass top I used for Arrakis 3.0 was 8mm thick and beveled. I got it cheaply via Craig's List because I wanted to try painting the LED frame on the underside of the glass and wasn't sure if I would like it. The painted LED frame was good, but the top surface of the glass had some pretty big scratches that were visible in daylight, but not visible when the table was lit up at night. 

I decided to get a new glass top for the sand table so I wouldn't have to see the scratches, at least until I put some new ones in it. I ordered a 12 mm thick, beveled, low-iron glass table top. It weighs over 23 kg (~50 lbs), so I also ordered some surprisingly cheap ($35 for a pair) vacuum handles to make dealing with the glass easier. Each of them can hold about 350 lbs, so they are very secure. The only problem with using them is that when the glass is set back on the sandbox, removing the suction handles creates a triboelectric charge that induces the opposite charge on the underside (the sand side) of the glass, and that charge picks up some of the sand and sticks it to the glass. Doh!

Sand stuck to underside of the glass after I removed the vacuum handle. This is exactly the opposite of what I want!

But what to do with the old sandbox frame?

Back when I first tried servomotors in "The Spice Must Flow" sand table I replaced the magnet with a blue LED, set the mechanism on its side in the dark, pointed my camera at it, opened the shutter, ran a drawing on the mechanism, moving the LED around, and when it finished the drawing, I closed the camera's shutter. I got pictures that look like this:

Light painting made using the Spice Must Flow sand table mechanism with servomotors. The controller applies acceleration and deceleration to the motion so whenever the LED is going to change direction the painting looks brighter because the LED was there longer.

The only way to see this light painting is to look at the photo. But I had another idea. What if I lit up a glow in the dark surface with the LED? 

The most common glow-in-the-dark stuff contains zinc sulfide. That's what you'll find in GITD 3D printer filaments, paints, and most GITD toys because it's very cheap. The glow isn't very bright and doesn't last very long, but there's something better. A compound called Alumane Dysprosium Europium Oxidanylidene Strontium (commonly called strontium aluminate) glows brighter and lasts longer. 

I painted the old glass with strontium aluminate paint for the light drawing. Then I mounted a UV laser on the magnet carriage, pointing up at the GITD paint. 

Painting a 3rd coat on the underside of the glass table top.

Daylight visibility of lines drawn with UV (405nm) laser pointer. The dimmer lines were drawn about 3 minutes before the brighter lines. The lines were drawn in about 2-3 seconds, so high speed drawing will be possible. Note, the laser pointer was hand-held maybe 300-400 mm from the paint surface.

Night time visibility of lines after about 10 minutes.

Tests look very promising, as you can see in the photos. 

There are some important differences between drawing in sand and drawing with light. One of the more important differences is that when drawing with light, there's no sand being thrown around and sticking to the glass, obscuring the view of the drawing. That means I can crank up the speed on the patterns so they will finish very quickly. Also, there's no need to erase the light drawing- it fades away after several minutes.

That's all very nice, but once I mounted the laser on the magnet carriage, I realized there was a problem. When the laser hits the painted surface and makes it glow very brightly, there are internal reflections in the glass top that create a halo around the spot lit by the laser beam. That halo is not as bright as the spot hit by the beam, but it is bright enough to cause the surrounding paint to glow. That wrecks the contrast and makes drawings look fuzzy- not exactly the effect I was going for.

It's also uncomfortably bright to watch it drawing in a dark room.

The halo problem. I've tried several types of internally baffled tubes, etc., to remove the halo until I realized it's caused by the glass table top, and not the laser optics.

You can see the bright halo around the laser beam. The red and blue light comes from the electronic status LEDs on the controller board which I later fixed with some gaffer's tape.

3D printed laser module mounted in the magnet carriage. There's a 500 mAH LiPo battery and a NC reed switch (with a disc magnet attached to keep the laser off). 

Unfortunately, this was a failed experiment. I may look into using laser galvanometers to steer the beam to draw on a wall painted with the GITD paint. There won't be any halo problems that way, and it will be a small, quiet box that does the drawing. I'll have to see if there's some hardware/software out there that can translate gcode in the drawing files to voltages to drive the galvanometers. I may have to come up with that myself.

Wiim Amp Ultra for Quad ESL-63s and SVS 3000 Micro sub

A while back I bought a Wiim Amp Pro (WAP) to replace the electronics in my bedroom stereo system. After I realized the bass management can be used as a crossover, I decided to try it in my living room system, driving the Quad ESL-63s that I recently rebuilt, and an SVS 3000 Micro subwoofer. I was impressed with the Wiim amp's performance and decided to put the WAP back in the bedroom and I bought a Wiim Amp Ultra (WAU) for the Quads/sub (20% off on Black Friday!). The WAU is similar to the WAP, but uses a different DAC and has a higher power output- 100W/ch at 8 Ohms and 200W/ch at 4 Ohms. It also has a touch screen I don't really have a use for.

Wiim Amp Ultra sitting on top of SVS 3000 Micro subwoofer.

The WAU has been reviewed ad nauseum:

WAU at Audio Science Review

WAU at Soundstageaccess

WAU at Darko Audio

But why?

The Quads, as wonderful as they are, are not perfect. The upper end of the audio spectrum (beyond my ability to hear it) is rolled off a little (easily corrected with an equalizer in the WAP or WAU), and they are incapable of producing low bass. Some people also complain of limited "dynamics" and maximum SPL - to me those are the same thing- if maximum SPL is limited, of course, "dynamics" will be limited.

The Quad's poor bass performance can be blamed on two things. First, they are bipolar radiators which means they emit sound from both the front and back sides. The front side and back side radiation are 180 degrees out of phase, so when the sound wavelength they produce is long compared to the size of the speaker, the front and back radiation tend to cancel and the result is weak bass. Second, the spacing between the diaphragms and stators in the drivers limits the maximum diaphragm excursion, and thus maximum sound pressure level (volume). The greatest excursion is demanded when reproducing low frequency sounds, so if you can prevent those low frequencies from going to the Quads, they can play everything else louder. This also addresses the "limited dynamics" some people complain of. 

The bass management in the WAP/WAU can be configured to keep the lows out of the speakers and send them directly to the subwoofer. The crossover is a Linkwitz-Riley 4th order type which means the low frequency roll-off in the Wiim amp will be 24 dB per octave below the crossover frequency. One octave is a doubling (or halving) of frequency, so one octave below 90 Hz is 45 Hz. So at 45 Hz, the signal going to the Quads from the amp will be 24 dB below what it would have been without the crossover being turned on. That means the Quads will be able to play much louder than they would if the full range signal were being sent to them. 

Linkwitz-Riley crossover response curves for 2nd (12 dB/oct), 3rd (18 dB/oct), and 4th order (24 dB/oct) implementations. The WAU/WAP use the 4th order curves. This image comes from the Rane site linked above. No, there won't be a suck-out at the crossover frequency. When the outputs of the drivers are summed acoustically, in your room, the response at the crossover frequency will be flat.

The SVS 3000 Micro sub has an 800 W amplifier built in and can produce lower bass at much higher output than the Quads ever could, so configuring the amp and speakers this way is a win-win situation. I get the lows that the Quads can't produce well, and the whole system can play louder. This is going to be true of any speakers you use that have poor low frequency output/response, including about 99% of all bookshelf speakers.

System Setup: The Subwoofer

The Wiim amp's bass management and the subwoofer can both be configured via my phone or tablet. It's a little bit of messing around, but once the configuration is done, it doesn't need to be done again. 

Connect the sub output on the Wiim Amp Pro to the LFE input on the subwoofer. Open the SVS app on your phone and switch to LFE mode - that tells the sub's DSP that it will only receive low frequencies at its input so it doesn't need to run a low pass filter of its own. In my system I set the subwoofer output to -20 dB, but your system may need a different setting. This can be changed later, as needed.

Much more detail here.

System Setup: The WAP or WAU

Connect the speakers to the jacks on the back of the amp and the sub output to the subwoofer's LFE input. Open the Wiim Home app on your phone. Select the amplifier and open its settings menu. Select the "Sub Out" item. Turn Sub Output on, set the level (start at 0dB and increase later if needed), set the crossover frequency (the default is 80 Hz which is pretty good for most speakers, including the Quads), you'll set the phase later, so don't worry about it for now, switch "Subwoofer Bypass Mode" off, and "Main Speakers Output Bass" off.

Play some music that has some low bass. As you listen, flip the phase switch back and forth between 0 and 180 degrees. At one setting, the bass response will experience a dip and at the other setting, a peak. You can usually hear the difference pretty distinctly. 

The final setting to make is to use the Wiim Amp's bass sync feature. The subwoofer and Wiim amp both have some delay resulting from the signal processing that goes on in their DSPs. There may also be a different "time of flight" between the main speakers and the sub and your listening position. Ideally, you want the subwoofer to be time aligned with the main speakers. The Wiim amps have the ability to perform the synchronization built in, but it's less than ideal. It uses a mic built into the amp to pick up test signals generated in the amp. It will then report the delay and adjust the signal(s?) to the main speakers and sub to be properly time-aligned. It would be better to use a mic at the listening position (as RoomFit uses), so right now, to do it right you have to put the amp at the listening position when you run the bass sync. Fortunately, using a mic at the listening position is possible in the latest beta release of the firmware for the amps, so in the near future you'll be able to use the same mic you use when you run RoomFit at the listening position.

More details here.

I set up Roomfit in non-boost mode to adjust response from 20-200 Hz using a Harmon target curve with ERB smoothing and plugged a UMIK-1 calibrated mic into my tablet and here is the result:

Then I turned on the PEQ and boosted the response above 10 kHz by a few dB. Finally I ran the subwoofer and main speaker sync and it set an 8ms delay on the sub and it all sounds great.

Listening

When I want to play music, I select it via Tidal Connect or LMS and touch the play button on the screen. The Wiim Amp Pro wakes up and starts playing which triggers the sub to start playing within a few seconds. I can start, stop, select new music, skip ahead, skip back, and control volume, all from my phone, so there are no remote controls to hunt for or juggle and I don't have to go to the amp and sub to turn them on. They just start when I want to hear music, and when the music finishes, they both drop back into standby mode. 

The amp can be placed out of sight, under furniture or in a cabinet, because there's no need to touch it. Do give it a little ventilation though because as efficient as class D amps are, they do generate a little heat:

WAU top side thermal image after playing for an hour at moderate volume, with low frequencies routed to the SVS 3000 Micro sub.

WAU bottom side thermal image after playing for about an hour at moderate volume.

This sort of operation won't satisfy you if you prefer to handle records or CDs and/or you like to twiddle knobs and flip switches, but for me it's ideal.

And in case you are wondering, yes, it sounds great! If you want more flowery superlatives, see some of the video reviews linked above. I don't have the vocabulary that those guys do. 

Arrakis 3.0 Updates- Now It's Arrakis 3.1

Update 3/31/26

The mechanism started making noise again, so I opened the table up and found that the belt was climbing on the corner pulleys, and that was wearing the edges of the belt and leaving bits of black rubber from the belt everywhere. The noise was occurring when the belts would climb the pulleys, increasing tension, and then snap back toward the center of the pulleys. 

I redesigned and printed the corner pulleys on the end of the stable opposite the motors to have a flat profile instead of the concave profile the other pulleys have. For some reason it only seems to be a problem at that end of the table. It's been running quietly again for several hours. I'm going to wait a while and see if I should replace the other pulleys with the flat profile type.

Now back to the original post: 

After living with Arrakis 3.0 for a few months, a few problems have led to some changes. 

1) The cheapo 6A rated power switch welded itself in the "on" position about the fifth time I switched the table on. The table has a 350W power supply - 6A should be plenty of capacity. 

2) I noticed that quite a few of the patterns started with the ball rocketing from the home position to one of the opposite edges of the drawing area, drawing a straight line across the table before the actual pattern started to be drawn. Sometimes the pattern was dense enough to wipe out that line, but very often it wasn't. I found that really annoying.

3) I noticed that the table started making some small noises only a couple months after I finished building it. That suggested parts were wearing.

4) I run the table in random mode most of the time, where the table randomly selects a pattern to draw from over 200 patterns stored in the controller's memory. Sometimes it draws a nice pattern that I'd like to keep on the table for a day or two. The only way to do that is to switch off power, which means the LEDs are also switched off. I'd prefer to be able to have the LEDs on without the table drawing any new patterns.

Changes

1) After checking the LRS-350-24 power supply specs and finding inrush current rated at 60A maximum (!), I replaced the 6A switch with one rated for 10A, and added a 16 Ohm 5A NTC thermistor and 3 second time delay relay (found in a box at the makerspace, with contacts rated for 7A @ 250V) to switch power to the table. Now when power is switched on, the thermistor is in series with the power line going into the power supply, limiting surge current to a maximum of about 10.6A (peak voltage on the power line is 170, so maximum current will be 170V/16 Ohms=10.6A, but only if I happen to flip the switch at the exact peak of the voltage). After 3 seconds, the relay closes and shorts out the thermistor. During that 3 seconds, the thermistor gets about 10C warmer than ambient temperature. This seems to have solved the power switch/surge current problem.

3 second time delay relay (the gray box) and NTC thermistor (the gray disc). If the relay ever fails, the thermistor will remain in the circuit and the table should continue to operate.

This is how the relay and thermistor are wired. Theoretically, I shouldn't need the relay at all as the thermistor resistance drops when it heats up, but I'd prefer not to have it sitting there hot when the table is powered up. If the relay ever fails, the thermistor will still be in the circuit and it should continue to operate with the thermistor sitting at an elevated temperature.

2) I manually edited all 223 pattern files and eliminated the lines that went across the table at the start of many of the patterns. I also eliminated some odd back-and-forth-along-the-edges motion that occurred at the start of some patterns. I'll be more careful to remove such lines before uploading new patterns to the table.

3) Arrakis 3.0 had wheeled carriages running in v-slot aluminum for the Y axis. I suspected that this is where the noise was coming from. When I opened up the table to inspect the mechanism I found that the Y axis carriage wheels on the outside of the mechanism frame were wearing out and the wheels on the inside of the frame weren't even touching the frame. The wear pattern is the result of the tension on the belts pushing the carriages inward while the attachment to the X axis linear guide is loose (by intention, clearly a mistake), allowing the inward motion and some tilting. It was a very bad design!

For the MakerFest in Elkhorn, Wi. on Feb.14th, I installed wheels that were made of some mystery material that was supposed to be "self-lubricating", and it restored the table to quiet operation. When I got the table home I opened it up to look at the mechanism and think about what I could do to improve it, and found this:

Self lubricating?

Arrakis 2.0 uses UHMW blocks sliding in the aluminum slots and has been 100% reliable for years. I decided to try converting the wheeled carriages in Arrakis 3.0 to use UHMW blocks instead of wheels, and to solidly attach the X axis linear guide to the two carriages. 

I found some UHMW in my stash that I was able to carve into sliding blocks to replace the wheels in the Y axis carriages. I tried it and it just didn't work out- the UHMW blocks fit loosely in the v-slots and the result was that the X axis tilted, making a noise each time the Y axis movement reversed direction. Even if they had fit well, as the mechanism wore in, it would have started making noise. Ugh.

The real problem with Arrakis 3.0 was that the X axis wasn't rigid enough. Each of the wheeled carriages could tilt due to the belt tension and that caused uneven pressure on the wheels resulting in uneven and excessive wear. Another problem is the limited accuracy of the construction of the mechanism and the use of just two eccentric adjusters at each of the wheeled carriages.

The solution to the first problem was to make the entire X axis more rigid, which I did by mounting the X axis guide rail on a piece of 1/4" aluminum tooling plate that spanned the width of the X axis. The 1/4" plate is flat and rigid, so it will flex much less (especially when screwed tightly to the X axis guide rail) than the two original 1/8" carriage plates that were loosely screwed to the ends of the guide rail.

Set up for drilling and milling the tooling plate for the X axis. Hole positions were critical, the milling was for weight reduction and cosmetic reasons (though it's inside the table and most people will never see it).

The X axis linear guide mounted on the tooling plate. 

The second problem was solved by using eccentric spacers for all the wheels. The first end is adjusted so all four wheels fit the V-slot rail, then, at the other end of the X axis, the adjusters for all four wheels are positioned to comfortably hold both sides of the V-slot rail. The holes in the eccentric spacers are offset from center by about 0.79 mm, so allow for about 1.58mm adjustment, which is more than sufficient. I would really prefer to spring load some of the wheels so they are always held in contact with the rails, regardless of imperfect spacing or flexing that may occur when the table is operating. 

I'm not sure about using 4 wheels at both ends of the X axis. If I just put 4 wheels (3?) at one end, the X axis assembly will follow the rail that it is clamped to by those wheels. Adding wheels at the other end over-constrains the motion. If the two Y axis rails aren't absolutely parallel, the second set of wheels may cause the mechanism to bind. This is why it would be good to have one set of wheels spring-loaded so they can allow for the rails to be out of parallel. Arrakis 2.0 has a spring loaded UHMW block at one end of the X axis for this reason and it works perfectly. In the end, I used 4 wheels at each end of the X axis. I will reexamine it when I see how well the wheels hold up in the new configuration.

Arrakis 3.1 left side of x axis. Yes, I know the screws holding the wheels are short- they will be replaced with longer screws when new wheels arrive and get installed.

Right end of X axis.

The tooling plate raised the X axis guide rail, belt clamps on the magnet carriage, and pulleys by 3.175 mm. That meant I also needed to raise all the corner pulleys and motors/drive pulleys, and endstop sensors the same amount. I had to modify and reprint all the motor mounts, end-stop sensor mounts, and corner pulley stand-offs. Raising the X axis guide rail also raised the magnet, so I reprinted the upper belt clamp part of the magnet carriage to lower the magnet so it stays at the its original vertical position and doesn't scrape the bottom of the sandbox.

Magnet carriage. The green parts is the new, thinner version that was needed to lower the magnet and prevent it from scraping the bottom of the sandbox. The gaffer's tape wrapped around the magnet keeps it from lifting up 

Note: the 3D printed PETG concave pulley flanges and motor mounts appear to be holding up just fine, as are the belts. There are some rubber crumbs around some of the pulleys, but that's to be expected. Eventually the belts will wear out and have to be replaced, but it won't be any time soon. I tried moving the twists in the belts from the short segments between the drive pulleys and the corner pulley blocks to the very long segments between the corner pulley blocks and opposite ends of the table. I was originally concerned about noise from the belt teeth hitting the pulleys at the corner blocks and with belt clearance along the long sides of the mechanism. Neither seems to be a problem, so I left the twists in the new positions. 

I may take another crack at using sliding UHMW blocks instead of wheels, depending on how well the wheels hold up with the new X axis configuration.

4) The solution to the LED problem was to install a switch that allows me to cut 24V power to the controller board. There are now three switches located on the underside of the table, one for main power, one to control power to the controller board, and one to switch power to the floor lights on the underside of the table. 

Here's the mechanism running: