The Objective2 (O2) Headphone Amp DIY Project

[lorriman]

Awsome!! What type and size of reamers did you use? Were they tapered hand reamers?

Originally Posted by chickwhite

Got a few tips on drilling the front panel. I printed out the front panel label adjusted to exactly fit the panel. Cut it out and taped one edge of panel printout and aligned it to the panel and hinged it open. Then I got some double sided scotch tape and laid three rows down on the top of the panel and folded the label back over the top of the panel. Got it right the first time. (The label has cross hairs at the center of each hole position.) Then I used an auto-centerpunch to dimple the center of each hole position. A hammer and nail or regular center punch just doesn't work for me. I always seem to lift the punch and end up with the dimple off center. I had some scrap plywood that was much bigger than the front panel, so I screwed the panel down to the plywood with the screws that came with the enclosure. Now I drilled out the holes with an 1/8th inch bit for the LED and a 1/4th inch bit for all the other holes.The paper/tape kept the burrs to a minimum on the top and the wood did the same for the back side. Now take a long thin reamer and use it to de-burr and enlarge the holes as necessary. I used a hand drill with some titanium-oxide coated drill bits.

Next I intend to gin up a front panel label and print it on glossy photo paper and spay the label with fixative and I'll an OK front panel.

[agdr]

matthaios - you did pretty well for the first time with a soldering iron! The small 1/8 watters can be hard to spot a bad joint on, even with a magnifying glass. Reheating solder joints in a suspect area is always a good first step to try.

[chickwhite]

Originally Posted by lorriman

Awsome!! What type and size of reamers did you use? Were they tapered hand reamers?

Yes, it is a hand reamer, tapering from 1/2 inch to about 1/16th of an inch over a distance of 4-5/8th inches. I bought it in the 1970's for 2 or 3 USD. I have no idea what one would cost today. See the photo in the original post.

[RocketScientist]

Originally Posted by agdr

matthaios - you did pretty well for the first time with a soldering iron! The small 1/8 watters can be hard to spot a bad joint on, even with a magnifying glass. Reheating solder joints in a suspect area is always a good first step to try.

The above is really good advice--a magnifying glass and/or eye loupe (4X - 8X) can be really useful for checking for soldering problems. That's especially true for those who wear glasses or contacts. Fine solder bridges can be difficult to see with the naked eye--especially where the spacing is really close like the O2's regulators and MOSFETs.

And I agree those who built an O2 as their first DIY project have a lot to be proud of. It's not a trivial build with nearly 80 components and a fairly cramped PC board layout.

[Alexium]

I think the thing you need most when assembling O2 is attention. O2 is my first serious project (not the first time I hold solder iron, though), and I have to say it is awesomely designed and extremely easy to build (thanks again, RS! ) There are no SMD parts (my personal opinion - you have to be a neurosurgeon to solder those by hand), there are no closely located pads that would be easy to bridge... Consider this: the tip of my iron is 3.5 mm in diameter, and I have no skill, and I have assembled it right with the first try! I didn't have to re-solder a single part! If I can build it - everyone can build it.
It is indeed much harder if you need optical devices to see clearly, though.

[greenalien]

There are no SMD parts (my personal opinion - you have to be a neurosurgeon to solder those by hand)

+1 - although if you ever do have to solder SMD parts, particularly those with multiple pins, it can be effectively done by sticking the part accurately in position with a very small blob of hot melt glue, then soldering the part into place without worrying about bridging any pins, and finally removing excess solder with desoldering braid, which then unbridges the pins.

[tschuss]

After receiving the front panels from the GB (thanks @Flynhawaiian!), I finished my second build last night and everything passed with flying colors.

I thought I had a strange voltage issue at first, but then realized I had temporarily forgotten that the pin locations on DIP8 packages count in anti-clockwise fashion, not columnar.

Thanks again, RS. You've really made it easy to enjoy both the build process and the end results. Now Santa just needs to bring me some new cans for Christmas so I can REALLY appreciate it.

I can't even fathom the amount of time you've given to this project (the documentation alone is jaw-dropping), and just really want to say a heartfelt THANK YOU for everything.

[RocketScientist]

And a heartfelt thank you in return. Happy Holidays and Happy Listening! The more people look like the little guy under the batteries the more the time investment is worth it.

[billyk]

There are no SMD parts (my personal opinion - you have to be a neurosurgeon to solder those by hand)

Don't be afraid of SMD work. I have come to almost prefer it. Once you get the hang of it... I think you might like it better than through hole! Just think no more leads to trim!! Try a Grub DAC, a good entry into SMD and a fine sounding low priced piece of kit that will go nicely with your ne O2!!

[Alexium]

billyk, my hand is just not steady enough for SMD, it shakes too much. I'd prefer to cut the leads, at least that's possible for me I get your point, though. I think I'm a bit jealous to those who can actually solder SMD