The Objective2 (O2) Headphone Amp DIY Project

[BuildMeSomething]

Originally Posted by lorriman

Anyone got any ideas for making an ODAC sized USB hole for the rear faceplate?

I successfully drilled holes for the frontplate. However, a drill is all I have so right now it seems like I'm going to have to drill a large, round hole for the ODAC usb port and then find some way of making a surround (perhaps with a glue gun). Any suggestions on making surrounds would be great also.

Hmm, I'd think about investing in some Needle Files, drill one hole and file out the shape needed... should take less than 20 minutes.

[jtktam]

Originally Posted by BuildMeSomething

Hmm, I'd think about investing in some Needle Files, drill one hole and file out the shape needed... should take less than 20 minutes.

I used to do this and it works well.

just make sure that your needle file is perpendicular to the hole, then you will get a nice even surface, otherwise your hole will get bigger and come out all crooked

in the beginning work slow and get a feel for the technique.. i usually use a marker to mark off sections that is "high" (needs more filing) and then mark on the panel where to stop filing (edge of hole)

-joe

[4nradio]

If Tandy in the UK is like Radio Shack in the US, they sell a "nibbler" tool meant to cleanly cut small squares of soft metal or plastic sheeting. To use the tool you just drill a small access hole for the tool and then you can create straight-edged cuts and openings easily.

My "nibbler" tool has saved the day on a number of DIY projects.

Here's a link to what I'm talking about:
GO! MOD Nibbler 29524 Metal Cutting Tool : General tools & tool kits | RadioShack.com

Originally Posted by lorriman

Anyone got any ideas for making an ODAC sized USB hole for the rear faceplate?

I successfully drilled holes for the frontplate. However, a drill is all I have so right now it seems like I'm going to have to drill a large, round hole for the ODAC usb port and then find some way of making a surround (perhaps with a glue gun). Any suggestions on making surrounds would be great also.

[jtktam]

For my friends in Toronto, I got mine from Sayal

TOOL NIBBLING CUTTER UP TO 18GA

-joe

[jschristian44]

Can anyone point me towards a Front Plate stencil so I can make my custom desktop version O2 amp? I want to have the RCA red/white plugs as well as the 1/4" adapter. Does the 1/4" adapter go on the front and the RCA plugs in the back? Also how do the RCA plugs attach as well as the 1/4" adapter. Thank you!

[jtktam]

Originally Posted by jschristian44

Can anyone point me towards a Front Plate stencil so I can make my custom desktop version O2 amp? I want to have the RCA red/white plugs as well as the 1/4" adapter. Does the 1/4" adapter go on the front and the RCA plugs in the back? Also how do the RCA plugs attach as well as the 1/4" adapter. Thank you!

depending on the jacks you use, i think there was a groupbuy on the b3 panels, they should have pictures or template there

the rca would go to the back and be wired into the input header
the headphone jack would go in the front and be wired to the output header

you would probably want to relocate the volume control to the front as well.

-joe

[agdr]

Originally Posted by PATPP2

hi,
I suspect mosfet Q2 is out
i found an IRF 630 from a supplier near me,but the VGS is +-20v,where i can measure vgs?
Will it works or burns or only works with battery(2X9)
thanks for help

Vgs(max) of 20Vdc for the mosfets won't work (for very long, anyway). The power supply rails when running on AC are +/-12Vdc, so there is 24Vdc rail to rail, or more like 23Vdc after voltage drops across the schottky diodes and comparator chip output. The " 9v" NiMH batteries charge up to around 10.5Vdc, as I recall. That results in 21Vdc rail to rail when running on batteires, or right at 20Vdc after the various voltage drops.

So... you should get a mosfet with a Vgs(max) of at least 25Vdc. All the alternate mosfets RocketScientist lists in the BOM have Vgs(max) = 25Vdc.

Good luck!

[coolhead]

Found some low ppm (<50ppm) 0603 surface mount resistors in drawer. Decided to replace R14, 20, 16, 22, 12, 13. Also add bass boast R16 and 22 with 0.1uF film cap as agdr suggested in the other post.
After done, hock it up to my BII DAC, I listen to it for 3hr. All i can say is, It is very nice to my ear, I like it a lot.

Did know how to upload picture with iPad. Maybe later will upload.

[coolhead]

Originally Posted by coolhead

Found some low ppm (<50ppm) 0603 surface mount resistors in drawer. Decided to replace R14, 20, 16, 22, 12, 13. Also add bass boast R16 and 22 with 0.1uF film cap as agdr suggested in the other post.
After done, hock it up to my BII DAC, I listen to it for 3hr. All i can say is, It is very nice to my ear, I like it a lot.

Did know how to upload picture with iPad. Maybe later will upload.

Here is the picture, the picture is not so good as I am using mobile phone to capture it. All old resistors are removed and new SMD resistors are mount underside of the board as it is easier to work with. IMG-20120519-00191.jpg

[agdr]

Originally Posted by coolhead

Here is the picture

Hey that is pretty slick! You found a way to use the (bigger than ceramic) film caps for the boost mod by sticking them on the bottom. I like the contrast there, the tiny SMD resistors and the huge 0.1uF film cap. That is what is needed electrically though. Looks like you are not going to use a switch on the boost mod (on all the time)? Another fellow has tried the boost mod and discovered the switch really doesn't fit anywhere in a B2-080 chasis. Have to go to B3. I just wired it all up to make sure it worked electrically, but hadn't tried to mount the switch in the box and got caught flat footed on that one.