Beta22 - Headamp for dummies

Having all your boards soldered might be fine, but the Beta22 (and Sigma22 as well) deserves a nice home, so head to the workshop and start scroungin' for parts for your enclosure!

There is a first for everything they say, this time I decided to have custom fronts made for me. This is what I got. Take a good look now, since I will be covering them up.

Ouch! So much for sexyness, but putting masking tape on the front panel helps protect it so that it does not accidentally get scratches and marks as I machine it.

The only thing I was absolutely dead set on at this time (I admit to having made some rough sketchups prior to ordering the front panels and casing though) was the placement of the headphone jack. So, off with the masking tape to allow for some drilling! I made the hole for the jack first, then I made two through holes with a diameter of 2,5mm and threaded them with an M3 tap.

I now went on to the detail planning phase, putting things on the bottom plate and front and rear panels roughly where I wanted them to check if it was doable and made sense.
Do take note that I decided to place the volume control at the back, this was done as, apparently, the "line in" does have a bad habit of picking up noise and this noise will then be amplified. Therefore, I decided to keep the input wiring as short as possible...

In order to be able to mount the volume potmeter on the back panel I manufactured a small aluminum bracket. This bracket will allow me to mount the potmeter to the back panel with threaded machine screws.

I made the hole for mounting the potmeter and the input sockets. Not in the picture is the hole I made for the power jack.

The finished back panel, all holes are "through holes" (not threaded holes).

...and there we go. I hope the mounting bracket makes sense now! Both inputs have been soldered to the volume control and GND wires have been connected.
If you have not noticed it, the input GND has not been tied to the chassis in the above picture! I forgot that initially and had noise in the amplifier, tying GND to the casing eliminated all hum!
Oh, and please read the instructions on proper "earthing" / "grounding" your amplifier as the instructions does vary for versions with internal and external power supply!

I marked all mounting positions for the Beta22 boards, drilled the holes and put hex screws through the holes and screwed standoffs onto them...

I braided wire for the "plus", "minus" and "ground" and soldered them onto the bottom of the boards.
Using this colour scheme was actually rather stupid! It seemed to make sense that each channel got its own colour, but since I only had red and blue wire the GND board got a mixed braiding... Also, colour-coding based on channel is nonsense for power supply really and I should have used the colours to identify GND from V+/V- or even better, used three wires in order to more easyly identify each line. That would have saved me A LOT of probing with the DMM later to check, double-check and TRIPLE-check that I had gotten it all right!
Then the boards were flipped over and the output wires were soldered onto the boards.

First test fit... Luckily all boards fit!
The GND board is to the left, right and left channels are the two rightmost ones. The space to the left will be used for wiring to the power jack.

Bottom plane and back panel was joined as well as the sides. It is a tight fit!

Now I drilled the remaining holes in the front panel. The circular pattern of 12 countersunk holes are for the volume indicators as you might recall a design goal of mine was to allow for it to "go to 11". The center hole is for the volume control and the pattern of threaded holes (those are NOT through-holes) is for the Epsilon12 protection circuit. If you look carefully you might be able to figure out that I originally intended for it to be mounted "horisontally", but I had to redo that part so I ended up with some excess holes...

That centre hole... You guessed it, it is for the volume control. I would have liked to "sink" the volume control knob into the front plate, but since I wanted a big knob and since I also want to do things myself I had no way of drilling a 30+mm hole in the front plateso instead I opted to make whatever I came up with as smooth looking and feeling as I possibly could. To make sure turning the knob would be an out-of-the-body experience (or, well close to) I mounted an axle in a ball bearing. Picture above shows just how I did that and whilst not the most elegant of methods it worked.
When pressing axles through ball bearings, do remember to support the inner "ring" of the bearing when pressing your axle through.

Well, here it is, ready for the first test fit.

...and here is a snapshot from that very test fit. Volume control has been connected via a through-case axle to the front.

Power cables connected...

My first look at something resembling the final front.

Above you can see just how I secured the ball bearing to the front. I would have liked to make a press fit, but the bearings outer diameter was 21mm and I only had a stepped drill allowing for a hole of 22mm so I used washers to keep the bearing in place.
I prepared 12 LEDs by applying heatshrink to their legs in order not to short anything.

Next step was gluing the LEDs into place...

Next thing I "daisy-chained" all LEDs.
The headphone input was screwed in and the Epsilon12 was mounted. As these units are both mounted on the front panel I hard-wired them, no need for connectors if I can get to service the parts should I ever have to.

The LEDs legs were shortened and insulated so as not to encourage shorts. I also added a receptacle for the current-limiting resistor so that I may change its value in case I get unsatisfied with its brightness.

The Outputs were bundled in a pin receptacle and the power leads likewise. The front panel was mounted and the connectors plugged in. The volume axle was secured by drilling holes through the axles and securing them with locking nuts (those with a nylon ring).