Shakuhachi - pixelnull's BT speaker project blog

To get this started… A copy of my post over in the “What did you buy today?” thread.

So, I’m making my own BT speaker box for my basement work area. I’ve been ordering everything over time as I don’t own any wood working tools, so those need to be gotten over time.

There too many things I’ve gotten to list here but here are the important bits…

Arcane Stash Box Rolling Tray Combo With Spline Reinforced Corner Joints (11 x 8 x 4.5 inches and almost perfect for my application)

2x Dayton Audio RS100-8 4" Reference Full-Range Driver

2x Dayton Audio ND105-PR 4" Aluminum Cone Passive Radiator (These probably weren’t needed, but if they don’t help much it’s fine.)

DAMGOO 50W+50W Amp Board with Treble and Bass Control, Bluetooth 5.0 and AUX Input (I’ve already tried this and it’s pretty good actually. Distortion happens if you go loud, which might be the speakers hitting their limit, but I’m not looking for super loud. I might even step down the internal voltage to help with this. Otherwise it has impressive performance for the price and for what it is.)

It will have a laptop 3 prong 120v input on the back and a switch, which will lead to the internal power supply. The amplifier board won’t be able to be seen, just the flush mounted knobs for adjustment, the speakers/radiators, a status light, a flush mounted aux jack, and the flush mounted power switch/input.

Here’s a picture of the wholly unlabeled schematic I’ve done for fitting and planning cuts (be kind it’s my first attempt in Fusion 360):

(Front, Back, Left Side, Right Side. Units = mm)

I originally wanted it to be mono, but I had the room/budget for stereo sooooo… v0v

I had to source parts from all over so I have to wait until next weekend to start work on it. Although I don’t have a good way to record how it sounds, so you’ll just have to take my word for it when it’s done.


noiceeeeeee, looking forward to it.

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So a little about context and the progress I’ve made so far.

First of all, I recently rebuilt my workbench in the basement, and as my personal computer faces the opposite direction the speakers (LSR 305 + BIC Acoustech PL-200) aren’t really helpful.

So I decided an easy project to start back would be making a BT speaker for this area. It also has been helping me get used to metric. It’s so much easier then dealing with fractions. It’s been making sourcing parts easier too as I can get Chinese part specs far easier and cheaper. All measurements here will be in millimeters, just because it’s my own reference. Also, fractional inches can kiss my ass.

As I said above, I initially wanted to go mono (mostly for listening to spoken content (podcasts/youtube) and some music), but I found the bamboo box above and it was perfect for what I’m looking for.

The Box:

(4" speakers for size comparison)

204mm h x 240mm w x 129mm d (lid on) / 119mm (lid off) walls are 10mm thick and the bottom is offset 5 mm with a 3mm bottom. It’s very well made, and if you need a box for anything (even not audio) I recommend it. The bottom is an insert and thinner the the other walls, so it rattles. But glue will fix that.

The top uses magnets to stay on, and since I am using it on it’s side, I needed a way to keep the lid on, but still be removable. This will be done with L brackets an M4*25mm threaded rod, two nuts, and a knurled nut. The two nuts cinch down on the L bracket and make a post. The thumb nut then lets me tighten the lid on. This allows me to take off the lid but still have a good connection. These will be on all 4 corners.

As far as acoustics go, I have no idea how this will perform. As long as it’s not obviously rattling though, I think I’ll be ok. If it’s too bad I start looking into doing the woodwork right. Although I did get foam to seal the lid and under the speakers.

The speakers (Active & Passive):

(Passive, Active. Forgive the testing cardboard box)

The active speakers have good reviews all around but have a fall off of about 120Hz, which is why I also added passives. According the calculators I’ve used, I’ll need to add 19-ish grams to the passives to lower their response. Which is doable with washers. The actives are 30W RMS, 60W peak, which fits well with the amp.

I have tested them and they sound nice. Although it was on one channel only and the box was too big for the active to get enough pressure to push the passives. It sounded even better, even on the cardboard with some cloth baffling (again, just testing).

The Amp:

As it has everything included I wanted I found it well suited for what I wanted (Ample power, AUX in, and BT 5.0). The test of the left channel being fed mono from my computer passed the quality I wanted. The only thing I don’t like about it is the fact that the included knobs are super cheap silvered plastic. I will be getting proper 6mm coarse knobs, like is used on guitars, so I should be able to find nice replacements.

If you’re astute you may have noticed a problem, I can’t mount those potentiometers directly to the lid, I am going to have to get some kind of thin metal plate to mount them to. Well here’s another one of my issues. I don’t have many power tools to deal with metal. Which brings me to my next topic, the metal mounting plates.

The Mounting Plates:

Literally just anodized black metal business card blanks. Only .8mm thick, 86mm x 54mm big, perfect. All I have to do is to drill some holes in it. Also they look amazing and professional. I also got a 10 pack so I can have them laser cut and engraved with labels at a later time.

The Power Supply:

The power supply is a generic Chinese laptop replacement one, 24W and 6A, plenty for what I need.I’m going to shorten the wires, but the barrel plug already fits the amp. Which I wasn’t planning on, so it’s even better. I’m going to have a flush mount IEC320 (computer 3 prong) plug which feeds the supply.

I have already taken off the plastic shroud, though I could easily bring this to be an external supply, I like the idea of having a 120 mains powered BT speaker.

The Light Pipe:

So there is a light on the amp that shows if it’s on (and BT connection info) and I want to be able to see that from outside. These will “pipe” the light for me, I just need to mount it to the mounting plates I have. Of course poking another hole for it.


All the bolts I got are in either silver or black and have a hex head with knurling. I wanted this to look as good as I could accomplish. And the knurling all over will help that.

The aux in 3.5 mm headphone mount I got wasn’t ideal, but it will work. It’s also going to have it’s own mounting plate on the left side.

The Name:

A Shakuhachi is a Japanese flute used by Zen Buddhist monks traditionally made of bamboo. I am going for a bamboo, silver and black minimalist look. So a music making item associated with bamboo and Zen felt right. I am working on a logo for it which will go on the front mounting plate. I also plan on having my signature laser engraved on the side plate above the aux in.

Once I get everything, I will update here. Let me know if you have any questions.


Awesome! I got power tools and no motivation.

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Nice project

Also nice little sign :smiley:


I figured somebody might see that. It’s normally on my desk at work.

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So last night I got a hair in me and just did the project. As I was a man on a mission, I didn’t stop to take pics of the process. I did some tweaking today and I can say now that I’m done.

Forgive me for not having a full breakdown, but I have been salivating over doing this for a month or so now and wanted to go through it and get it done.

Takeaways… I need better/more power tools for working with wood, or I need to go to laser cutting and 3D printing (as I’ve planned) sooner rather then later. Working with wood doesn’t seem to be my strong suit. Another takeaway is to rememer that everything can’t be accounted for in the planning phase. Bringing me to the next point… Things still left to do.

I need a low profile right angle headphone adapter. Which I will get another time. The clearance for the amp board and the back of the casing is too little for a “real” headphone cable to fit. I didn’t account for that particular spacing. Until I get it the aux in won’t work.

I also have a crack in the back that I need to glue back together. It’s dealing well, but during the hole drilling it cracked all the way.

Feet, it needs feet of some kind, rubber preferably. This will be something I can put off for a bit though. The feet will make it look a lot more finished.

Last thing I need to do is design a logo for it and put it under the knobs. I was thinking about doing a label for the knobs, but I don’t think I will now that I’ve seen it done.

The sound. I love it. The thing is audible down to 30Hz then up to 18k! While in near field, I can’t push the volume past 12 o’clock on the dial without it getting too loud. My wife immediately said she also wants one. So success!

I have a rattle at about 60hz, but I think that’s a wire inside that I might have to pin down better. Overall however, you can’t hear it unless you’re doing a tone sweep. Otherwise there are no real resonances that I can tell, and as it’s only a nice looking and loud bluetooth speaker, not enough that matter.

Anyways, enough of the typing. Here is the finished product in it’s natural environment: