Back again with the finish.
Ran into some unexpected problems this time. The first of which was that I realized the outer screws holding the jacks in place were going to run directly into the outer perimeter of the case, preventing closure.
EDIT: (Forgot to mention that all photos in this post and the previous post were taken with my new camera, the Panasonic DC-G9 and the Panasonic Leica 45mm F2.8 Macro Lens, except the last image, which was taken with the Panasonic Leica 25mm F1.4 Lens, and the thermals which were taken with a Seek Thermal RevealPro.)
View attachment 16141
I ground them down with a Dremel. Unfortunately, this was my first time doing this, so it's not pretty (it's on the inside, so who cares). I wish you guys could have seen the sparks coming off the steel screw though! Too bad I didn't get a video of that.
View attachment 16142
New Problem! The board doesn't fit into the case. See the left (white) jack down there? It's in the way because we set it too low when drilling the holes. I have the beginning marks of the area I need to cut on the PCB. That's right, I have to cut into the PCB. By some miraculous fool's luck, there is nothing important there (It's just a part of the extensive grounding plane, it won't be missed) except maybe the standoff hole... but I'm not using them, so it's time to cut!
View attachment 16143
Measured and marked.
View attachment 16144
Confirmed there is nothing there. No traces.
View attachment 16145
I don't trust myself, so I put a bunch of tape to protect the nearby components in case of a slip.
View attachment 16146
Little crooked. Doesn't matter.
View attachment 16147
Now it fits!
View attachment 16148
Just have to wire the inputs and outputs. Even with an appropriate tool, pulling the shielding braid out gets old... fast.
View attachment 16149
Also remembered I still needed to fit an op-amp, so I went for my tried and true LME49720.
View attachment 16150
Input wired.
View attachment 16166
Output wired.
View attachment 16152
Ready for testing! I didn't screw in the self-tapping screws yet, because they can only be put in so many times before they strip out their own holes... hence the crap-tastic tape job... onwards!
View attachment 16153
Test commencing! But there's a problem. I keep hearing crackling and popping. I'm devastated. However, I remember from the WHAMMY thread on diyAudio that they recommend testing many different op-amps if the one you choose doesn't work well. I have an OPA2134, so I put it in instead. It fixed the issue!
EDIT: Forgot to mention, the DC offset was measured and was negligible: less than 1 mV.
The thermal images are next. I took these at various intervals of the test. There wasn't that much variation between the temps over an hour. I've chosen some of the most interesting pics. They progress from earliest (around 10 minutes) to oldest (about an hour).
View attachment 16154
View attachment 16155
View attachment 16156
View attachment 16157
Op-amp.
View attachment 16158
The power supply MOSFETs got up to about this temperature after ~30 minutes and stayed there.
View attachment 16159
View attachment 16160
View attachment 16161
This was the hottest that the other MOSFETs got.
View attachment 16162
An overhead shot without the center reticle.
View attachment 16163
The op-amp never got much higher than this. Since the OPA2134 max recommended temp is 85C (185F), I decided it was fine and didn't need a heatsink. There are some op-amps that operate at their upper limit (17V) when used in this design. Make sure you confirm what the op-amp can handle before using it. If it does approach its limit, you may have to use a heatsink on the op-amp or a different one altogether.
View attachment 16164
After testing, it was time to put it together and be done. I screwed on the panels, the volume knob, and put on some rubber feet. There's a slight gap where the backplate meets the top panel (it must have gotten warped during drilling or another process). It's not too bad though. Unfortunately, this amp doesn't really look new or shiny. There's a bunch of scratches all over it from mishaps during the build. It doesn't bother me, but maybe I'll get a blue Sharpie one day and try to touch things up a little.
Overall I'm really happy with it and am listening to it as I write this. It sounds fantastic, but that's just subjectivity. There's no hiss or anything I can hear, so it seems like a really good, clean amp. It also has a lot more range with the volume than my Millet Butte (and not so much gain), so I don't have to feather the knob on the low end to get even (but not deafening) sound. It gets more than loud enough when required. Also, there's only a slight blip when the unit powers on, unlike the Butte; which is loud enough that I started unplugging my headphones before powering it on.
If you've been thinking about building one, I say go for it! Feel free to shoot me any questions, or you can head over to the
official forum at diyAudio, where there's a proverbial army of people who have already built this, ready to answer questions.
I'll leave you with a glamour shot...
View attachment 16165
Thanks for looking! Until the next time I find something to build...