The Objective2 (O2) Headphone Amp DIY Project

[Bananaheadlin]

I have a quick question. The board I got from the Fall 2011 group buy of the last and latest v1.1 Sept release seems to have smaller holes for the J1 kobiconn DC jack. Has anyone else experienced this issue before?

It seems like the only choice I have right now is to somehow trim the very hard lead so it can fit in. To confirm, if I do so, I should make sure that one side of th lead is always touching one side of the PCB so it is making contact correct? Would it be bad if it didn't?

[sofaspud]

I recall RS answering this (or something similar) for another member earlier in the thread. You should be able to trim the lead with diagonal cutters. As to your latter questions, do you mean the lead making contact with the plated hole? That isn't absolutely necessary; the connection only needs to conduct the AC. For peace of mind you could bend the jack leads slightly in different directions. That should give the best possible mechanical connection, but you'll probably have a little harder time getting all the pins in the holes. Another instance when a small flathead screwdriver comes in very handy, to push the lead over just enough to fully insert the part.

[hubertus]

I have finished my O2 and its not working properly. The sound coming out is quiet, distorted and echo-y.

I have done all the voltage checks and the power supply section is fine. There appear to be no solder bridges. The only thing i can think of is that the voltage coming out of P2 is 4.2 mV in the bottom 2 pins when its meant to be 8 mV. This is exactly the same as what comes out of op-amp U2/U3.

I think it could be something wrong with the op-amps although i could be wrong.

Any help would be great!

THanks

[BamboszeK]

It should be under 8mV, so 4.2mV is well. Check that jack ground ale properly soldered. Sounds like grounding issue.

[sofaspud]

Give it another close inspection for bad connections and correct components. Looking at the schematic, reading your description is very bewildering to me.

[Bananaheadlin]

Does anyone seem to know anyone who sells acrylic or generally clear enclosures for the O2? I saw a seller that sells acrylic front plates on the forum, but he has been away for a while.

[availlyrics]

Sincere apologies to O2 purists, actually I didn't followed the exact BOM
This is just to show you an O2 with PC mother board style jumpers for vol.(next project-panel mounted stepped attenuator),gain, i/p & o/p.
Prime reason for using jumpers was to avoid accidental pressing of gain switch in my pocket. I'm planning to use PC CDROM type audio connectors for all connections. BTW All resistors are 1/4th watt.
I'm using 12VAC adapter that came with Creative spk. Even old dial-up modem AC-adapters will also work with O2.

[gopanthersgo1]

I'll be building this amplifier, what is the recommended part list if I want this to be my last amp?

[availlyrics]

Originally Posted by gopanthersgo1

I'll be building this amplifier, what is the recommended part list if I want this to be my last amp?

All the details at-
NwAvGuy: O2 Details

Step by step guide-
Building the O2 Headphone Amp

Ordering straight from Mouser is expensive(S&H 40$).
You can buy kits from jtktam (Audio Poutine) or swalter (Head n' Hifi) or many other GB. BOM is pretty standard, all you will be needing are couple of extra gain resistors ,suitable front panel & enclosure.
If you are not experienced builder maybe reading all the 3149 comments (incl. this)will definitely prove useful

[gopanthersgo1]

Originally Posted by availlyrics

All the details at-
NwAvGuy: O2 Details

Step by step guide-
Building the O2 Headphone Amp

Ordering straight from Mouser is expensive(S&H 40$).
You can buy kits from jtktam (Audio Poutine) or swalter (Head n' Hifi) or many other GB. BOM is pretty standard, all you will be needing are couple of extra gain resistors ,suitable front panel & enclosure.
If you are not experienced builder maybe reading all the 3149 comments (incl. this)will definitely prove useful

Thanks, any recommended op amps?