Directiva r1 speaker build

[Rick Sykora]

See Amir's review here!

Here is BOM...

So this is a build of the Directiva r1 speaker. I have not give much thought to a good naming scheme, so am calling it r1 for now. It is based on a Denovo cabinet sold by Parts Express (and others). Parts Express has changed suppliers, and the replacement cabinet should be available in March 2024.

https://www.parts-express.com/Knock-Down-MDF-0.56-ft-Bookshelf-Cabinet-300-7064

If you have worked with these flat packs before, you might have expected the back the be rabbeted, but in this case it is the sides. While clearly more milling is involved, this approach yields only one joint on each side and so offers a more even paint surface.

The back is in the bottom right and the front baffle is on the bottom left in the pic above. We will start with the front... (see next post)

P.S. (EDIT)

While using wood screws has not been an issue (as far as I know), in any of my earlier DIY speaker build for ASR, my rebuild of the Purifi SPK5s, brought some light to some ugly resonances that were apparently caused by wood scews rather than machine screws and nutserts or equiv. All of my subwoofers have used t-nuts, so given the excursion of the Purufi woofer used in r1, highly recommend using better fasteners to mount the woofer (and likely the tweeter too). As soon as I can do so with my r1 prototype, will retrofit and supply some measurements to illustrate the difference.

 

[Rick Sykora]

The front requires a hand router to properly recess the drivers. I like to start by getting out a square and compass and drawing my planned cuts. The front already has rounded edges and, since it is harder to see the edges as clearly, I start by drawing on the backside.

Forgot to get in a fuller pic before I cut it, but normally you’d see concentric circles showing the outer driver recess and the cutout. Apologize for not using metric measures, but all my tools are in standard! Will supply some drawings for those using metric system. So, next I find the center line on the 8.5“ width. Had to adjust as this one was slightly wider. Placing the square at the top, marked off tweeter center at 2 3/8 inches and 8 3/32 inches from the top. Then used compass to draw driver outlines.

Tweeter cutout is at 2 7/8 inch diameter and outer edge is at 4 1/8 inches. Depth should be .25 inch.

Woofer cutout is 5.75” and outer edge is at 6 15/16 inch diameter. Depth is at 3/16 inch.

Like the above pic the tweeter edge should be about 5/16” from top and a 3/16“ space between the drivers. If all is good, I repeat drawing on front for good measure and then drill centering holes for the router jig. Check back to ensure the center holes are aligned. If not, may want to mount the baffle on scrap backing board for cutouts.

Suggest you start with the more shallow cuts for the woofer recess and then move on to the deeper tweeter one. At this point, it is good to check the recess depths as once the holes are cut through will be more work to deepen them. My router depth gauge is not very precise and had to deepen. Will get to that later. Now I set up to do the cutout passes. I do each about a .5 inch deep and then flip over the baffle to complete. At this point, touch up with bit of filing and/or sanding and clean off any remaining dust.

Time to check the driver fit. The woofer is pretty straightforward, but until the terminal slots are cut, can only check the tweeter face down. If your recesses are cut slightly too deep, some gasketing tape can help. If too shallow, see below for my tip. If all is well. then time to cut the tweeter terminal slots. Centering horizontally on the tweeter midline, the slots need to be about 3/4" tall and 3/8" wide on each side. I use a square to draw them and then a 3/4" chisel to rough cut them. I file them to smooth the edges and then clean before checking the fit. If all is well, should look like this...

Before you forget, now is good time to mark the driver screw holes and chamfer the woofer cutout. I show this for the woofer below. I chamfered it and left some material for T-nuts. Even you do not use them, leaving the material around the left and right holes will allow more surface for them to secure to the internal brace.

Next you should prepare to glue the cabinet together. In my case, the woofer recess was too shallow and so here is how I dealt with that....

As I mentioned earlier, you can do this with a chisel, but if you want a smoother result, you need a rabbeting bit for your router. If they had them that were 5/8" wide, it would be the best way to do the driver recesses. The bad news is the widest in 1/2" and so a bit more work is needed. On MDF, this is not too bad. Once you have cut to the new depth with the router. take a small, sharp razor knife and carefully score along the recess outer perimeter. Now, take a chisel and use to lift under the remaining material. You may have to repeat with both tools a bit to clean the recess completely, but should get a good final outcome.

 

[Rick Sykora]

Now for the back panel. For this step, find the vertical midline and mark 2 centers from the top. One at 4 3/8 inches and the other at 8 1/4 inches. These are for the passive radiator cutout. Mark another 2.5“ from the bottom for the speakon connector. Using a compass, create at 4.75” diameter circles for the top center marks. Using a square, connect the outside edges of the circles to create an oval shape.

The speakon should be about 2 inch diameter circle if you want to recess it. Otherwise, you only need about a 1 inch hole for the speakon. The recess should be about 3/8 inch deep.

Here is the pic (with the top at the left)...

At this point, you can make your cuts, but I prefer to wait until the cabinet is assembled. This also allows you to cut the back edge of the internal brace at the same time. For the PR cuts, I use a 4.75 inch hole saw and trim with dremel. For the speakon, I use a 2 inch forstner bit for the recess and a 1 inch hole saw for the cutout.

 

[Rick Sykora]

Ok, so let’s start gluing this cabinet together. After a quick dry fit, decide to start by attaching the back to one one of the sides. I have plenty of clamps, but find them clumsy and like to use gravity when I can. Since these are nicely milled panels, all you really need to do is line it up and clean off the excess glue.

After I get the internal joints cleared of excess glue, I always check the joint against my table fence by sliding it along the fence and pulling away. Do not want to find that the glue has oozed out and end up with the cabinet attached to the fence!

Here is the initial pic. Note to remember to align the back bottom edge to the bottom edge of the side. This is key as the top is designed to have fewer exposed joints for a cleaner look...

 

[Rick Sykora]

Sanding the smooth edge of the top, applied glue and set it aside while adding glue to the top joint of the side panel. Next put the top in place, align and press the joints together. Remove any excess glue and push up against the fence.

Like so...

 

[Rick Sykora]

Now, the bottom...

 

[sgoldwin]

Rick, can you mention how/what you are doing to seal internal seams?

 

[Rick Sykora]

Rick, can you mention how/what you are doing to seal internal seams?

Thanks, good set up. This is why I have not glued the brace in yet. The extra room lets me readily maneuver my bottle of wood glue and add another bead along the internal seams. I usually put a liberal glue bead in the original joint and so is really just extra insurance against leaking.

If the joints are not as tight as these are, may add some rtv or latex silicone caulk along internal joints. I generally use wood filler on external gaps as want them to take paint just like the wood around it.

Another advantage of a rear mounted passive radiator is good internal access even after the cabinet is fully assembled. Notably access to the front baffle seams to give them some extra glue. Also, if using Sonic Barrier or butyl rubber dampening sheets, like to wait to apply these after a final sanding. It keeps them cleaner and less wood particles and dust from accumulating inside the cabinet.

 

[Rick Sykora]

And so after the extra glue is set, adding the brace is pretty straightforward. One tip is that you only need about an inch of glue at each end of the joint that attaches to the back. Later, when the passive radiator mount hole is cut, most of the brace will be removed anyway.

Just a quick measure to ensure it is centered and snug. As long as it is, does not have any direct effect on how well the cabinet seals. Should remove excess glue along the front edge as may prevent side panel from seating readily...

Once glue sets a bit, lay speaker on its side and check fit of remaining side panel.

 

[Rick Sykora]

Shown on its way to the garage, the other side was done last night as allowed the glue to set overnight...

You can see the pilot holes for the hole saw pre-drilled on the back panel. With the glue set on most of the box, allowed me to rough out the back baffle...

Will still do some filing and sanding, but unless you want to recess, just needs to allow the passive radiator to fit.

 

[renaudrenaud]

Wa want more!

 

[Rick Sykora]

Will likely be gluing the front baffle on tonight. After that need to complete fixing @phoenixdogfan EVAL-1 amp and taking some time to prepare for my parent’s 60th anniversary. Except for damping material, mounting and wiring drivers (already shown on the Directiva project thread, will just need to test to ensure I have decent match for the one I sent to Amir.

 

[Rick Sykora]

Snuck in a brief vacation and finished repairing the Purifi amp, so am ramping back up here.

Rather than have to refer to the other thread, left the front baffle off for now. This also allowed me to drill all the pilot holes (pics forthcoming) and more easily clean up afterwards.

Expecting measurements from Amir soon, so will show the last few steps needed to have the speaker ready for crossover design completion. So, the real fun is about to occur!

 

[Rick Sykora]

Here are pilot hole pics and, you may notice some additional recess on the woofer. This is because the woofer‘s outer flange is rounded and so is thinner at the edge than at the middle…

As did not recess the passive radiator, it needs to be centered. So, you see my marks for doing so on the rounded ends. It is about 11/16 inches from the edge. All the smaller holes are for #6 screws (tweeter and speakon) and the larger ones are #8.

 

[Rick Sykora]

Remembered how much fun it is to try to place 3/4“ Sonic Barrier with adhesive backing, so before gluing front baffle, I have installed it. Here is the bottom half…

This part requires 2 6.75” x 9.25“ side pieces. Put these in first!

The back is 5.5” x 3.75” with a 1“ inch hole for the speakon. Before you remove backing paper, mark the hole and cut it. I use a hole saw with the drill running counterclockwise. This yields a clean hole. DO NOT run drill clockwise - the teeth will tear the foam and likely ruin the piece.

Finally, the bottom piece is 5.5” wide x 8.75” deep.

 

[MrPeabody]

Hey Rick, I was curious about the stick-on sonic barrier vs. polyester batting. You obviously prefer the stick-on sonic barrier, and I was wondering why. I did a quick search to see if I could find anything in the way of tests to compare their effectiveness, but I didn't find anything. This is something I've been wondering about for a while but haven't come across any definitive answers.

 

[fluid]

I conducted some impedance measurements on different cabinet stuffing options in a speaker I built. I posted the results here
https://www.diyaudio.com/forums/ful...c9-line-array-cnc-cabinet-20.html#post5053920 if you aren't a member then the images might not show. Polyester batting was not much good on it's own, foam was better, fibreglass is good and felt and fibreglass was the best.

Another good combination was foam, felt and polyester batting which avoids the fibreglass if that is a health concern.

Any blip on the impedance response that is not there in free air is a function of it being placed in the cabinet so reducing those blips reduces the cabinets influence. You can overstuff the cabinet and that shows as an odd shape to the impedance peak.

Another good thread where many construction techniques have been tested is here
https://www.diyaudio.com/forums/multi-way/356130-monster-construction-methods-shootout-thread.html

 

[Rick Sykora]

Hey Rick, I was curious about the stick-on sonic barrier vs. polyester batting. You obviously prefer the stick-on sonic barrier, and I was wondering why. I did a quick search to see if I could find anything in the way of tests to compare their effectiveness, but I didn't find anything. This is something I've been wondering about for a while but haven't come across any definitive answers.

Like @fluid my choice is more empirical in nature. In the main Directiva project thread, I spent some time evaluating the damping material alternatives I have readily available. I agree there is a lack of definitive measurements to compare the various materials. What I am using is based on my prior evaluation and is subject to change, but seems a reasonable starting point. The Sonic Barrier I use has a nice combination of sound dampening and mechanical dampening properties. It serves as a foundation for additional damping with other materials like Dacron. Am not sure I tested polyester batting as had used it up on the Babgy speaker, so may be fine too, but is more like other fibrous materials I use for damping more open spaces. Since there are different damping considerations for the cabinet materials and the air inside the box, my experience is more than one type of damping is useful.

My approach follows from better commercial designs that utilize heterogenous materials to suppress resonances. Certainly more could be done, but cost and diminishing returns come into play as well. Am trying to strike a balance that is demonstrably effective and avoiding the common error of “more is better”.

 

[Rick Sykora]

The top is pretty much a mirror of the bottom with a shorter piece along the back AND a notch out the top where the tweeter goes…

Note, the one side panel is spliced as did not want to cut another sheet of Sonic Barrier for one section AND ensure you make a notch for the tweeter (not shown as I forgot ). The notch is 2.4 inches wide by 1.75 inches deep and centered on the top sheet.

 

[MrPeabody]

I conducted some impedance measurements on different cabinet stuffing options in a speaker I built. I posted the results here
https://www.diyaudio.com/forums/ful...c9-line-array-cnc-cabinet-20.html#post5053920 if you aren't a member then the images might not show. Polyester batting was not much good on it's own, foam was better, fibreglass is good and felt and fibreglass was the best.

Another good combination was foam, felt and polyester batting which avoids the fibreglass if that is a health concern.

Any blip on the impedance response that is not there in free air is a function of it being placed in the cabinet so reducing those blips reduces the cabinets influence. You can overstuff the cabinet and that shows as an odd shape to the impedance peak.

Another good thread where many construction techniques have been tested is here
https://www.diyaudio.com/forums/multi-way/356130-monster-construction-methods-shootout-thread.html

Thanks. As you expected, I wasn't able to see most of the attachments, however I was able to see the graph from your post #193. But even with that one graph I was unsure of the interpretation because there are three traces and I couldn't figure out what makes each of them unique. I was a member of diyaudio at one point and I suppose I should sign up again.