Wiring more bits, and a shot of the faceplate

I'm mostly at an impasse right now until I receive some shielded audio cable I'm waiting for Fedex to deliver, which may take a while. Apparently the package arrived in Chicago a week ago, then went up to Wisconsin, and is now back in Chicago and "In Transit" as of 4 days ago.

In the meantime, I'm trimming the shafts on the pots down so that the knobs sit at the proper height, and I wired the cue select LEDs. I'm not sure which knobs I'll be using for volume yet, so I am waiting to cut those down. One thing I discovered is that it's extremely difficult to cut something that rotates with a hacksaw, especially if you don't have a vise. The cutting wheel on my Dremel made quick work of the shafts though.

The cueing will be 1 channel at a time, with a blend between cue and master. The channel is selected via a rotary knob. Here's a shot of the LEDs in action, but obviously no audio yet (but at least I'm on track). This is the first visible sign of life from the mixer.

Primer, paint, sanding, etc

I decided to go with flat black for the base of this mixer, and a gloss ivory for the top. All of the features on top (knobs, dial plates) will be silver and black, so it should look pretty sharp against the off-white.

Just a tip: make sure your primer is compatible with your topcoat. Mine weren't, and I had to completely take the base and faceplate back down to bare metal with steel wool and a sanding block. It was not very enjoyable. I started with some generic old primer, and when I used a Krylon top coat it just dissolved the primer and everything wrinkled up and cracked. I ended up using a combo primer/topcoat from Krylon on the sanded metal, and everything is looking good so far. Here's a shot of the base with a couple connectors installed for the photo op.



Below, you can see the faceplate. I'm still adding layers to this one, I want to take my time and get a nice finish on it.



The vertical lines of holes on the left will be for the vu meter LEDs, mounted in metal bezels. The 4 holes on the bottom will be for the main volume knobs for the 4 channels, with the cue select LEDs mounted above them. Above that are the pilot holes for bass EQ, which will come later. The top 3 holes on the right are master, booth, and headphone volume, and under that is cue select and cue/master blend.

Case prep

The case is from Hammond Manufacturing. They had plenty of options. I would have liked something more compact but I thought it best to err on the side of having too much room to work with rather than not enough.

I started by designing the mixer layout in Illustrator - took a while for me to decide on spacing and arrangement on the faceplate. The rear was pretty easy. I used a sharpie to mark the protective coating on the aluminum case, then made pilot holes with my Dremel.



Then, the drilling of the holes. This led to a lot of tiny aluminum shards on the floor of my apartment, one of which hitched a ride in the bottom of my foot for a couple days.

Boards soldered

A quick shot of the soldered audio boards and the power supply, sitting in the unprepped case. Not too exciting yet. More to come.

Some catching up...

First, an overview and introduction.

I created this blog to document the building of my rotary mixer. The heart of this mixer lies in the boards designed by Bozure. Pern (Bozure is just 1 man) designs modular mixer PCBs that allow for pretty much the highest degree of customization imaginable, as the boards basically just provide a core functionality.

Bozure's circuitry is inspired by the Bozak and Urei rotary mixers of days yore. I am basically putting that functionality into a 4-channel desktop rotary mixer, with no bells and whistles and very high sound quality.

This mixer uses the 3 boards from Bozure's M1 project - 1 main audio board, 1 cue system board, and 1 power supply board which converts AC to +DC and -DC. For the most part, I am following Pern's own recommendations for components in this build, including using ALPS RK27 potentiometers which are probably the highest cost in the whole project. In addition to the Bozure boards, I am using Velleman K4305 PCBs for the LED VU meter (available as a kit), and future plans include phono preamps and bass EQ for each channel, both of which are still in development from Bozure). I plan on assembling the mixer and getting it operational as soon as I have the phono preamps, and adding EQ later. Eventually, having an isolator might be nice as well.

A bit about myself: I am an amateur DJ ("bedroom beats" if you will) but am very into the hobby. I like mixing various types of house, techno, disco / nu-disco, etc. I'm not going to be doing quick cuts or scratching on this mixer. I'm building it because I always wanted a high-end rotary mixer but couldn't justify the $1000+ expenditure. What I'm building isn't exactly cheap, but it's definitely in a different price range. I have some experience with doing some small electronic projects when I was younger (playing with phones, re-wiring a guitar or bass or two, just fixing little things), but I don't have a serious background in electronics or anything. Just doing this as a little (or maybe not so little) winter project.

Anyway, I'll update with pictures soon, hope you enjoy reading this blog.