The Objective2 (O2) Headphone Amp DIY Project

[tslonaker3]

How would I go about replacing the 3.5mm jacks with 1/4" ones? I bought these, which are surface mount. I understand I'll have to use wire between the holes on the board and the contacts on the jack. It's just not obvious to me which correspond.
NJ3FD-V Neutrik | Mouser

It looks like that has 5 contacts, but mine didn't come that way. I have the top one, then the two that are closest to it on the sides. I'm missing the bottom two.

 

[Turbon]

jtktam, here are some?

http://www.diyaudio.com/forums/head...eadphone-amp-diy-project-251.html#post3053835

What do you expect to see? Knowing that would make it easier to take the right shots.

Brgds

 

[DreadPirate]

I'm getting my parts list together. Is there anything special over the basic BOM that I will need to accommodate 16 ohm and 64 ohm headphones, in particular the Senn CX500 and HD570 which are what I intend to use with this unit?

 

[haejuk]

All you really need to keep in mind for driving your CX500 is the gain. You might not want the default 2.5x and 6x as your settings. I built my O2 with 1x gain as one of the settings to drive my IEMs. It is really easy, you just leave R17 and R21 (or R19 and R23) off.

 

[sgrossklass]

It would be useful to know nominal source amplitude (or the type of source), and whether the amp will be operated on batteries or on mains power.

Sensitivity is likely to be quite different between the two headphones. CX500s (assuming they are original) are specified at 113 dB / 1 V, while HD570s only output 102 dB / 1 V (at a nominal 64 ohms) and are almost as hard to drive as K701s. It would make sense to run one on low gain and the other on high gain.

 

[ramsfan6239]

How durable are the lines on the board? I was cutting the traces for the ODAC and I slipped a little and scratched the line above it. I can see a little bit of copper, like barley noticeable... is that ok?

 

[ethanolson]

How durable are the lines on the board? I was cutting the traces for the ODAC and I slipped a little and scratched the line above it. I can see a little bit of copper, like barley noticeable... is that ok?

There's a very high likelihood that you're absolutely fine.

 

[ramsfan6239]

There's a very high likelihood that you're absolutely fine.

Lol just making sure.

 

[xdanelliott]

Just finished my first o2 Amp!
Works great from battery, however, when powered from the AC adapter wau12-200 there is a very loud buzzing sound and no music is playing.

 

[sofaspud]

If your AC adapter is good, there is likely a component oriented incorrectly or a solder bridge creating a short. Inspect the DC jack, diodes, capacitors, & regulators for a problem.

 

[ramsfan6239]

So I'm doing my first ODAC, plug it in... and nothing happens. I get a very high pitched noise and nothing else.

Are there drivers I need to download?

 

[xdanelliott]

Are you on windows or mac, and what type of connection are you using(audio jack or rca)

 

[tschuss]

I hate to be "that guy", but this isn't really an ODAC thread....

 

[ramsfan6239]

Never mind it was my USB cord... don't know why.

 

[ramsfan6239]

I hate to be "that guy", but this isn't really an ODAC thread....

Oh like mine is the first post about the ODAC? Scroll back a few pages.

 

[tschuss]

Easy there, guilty conscience. That was for everyone posting about the ODAC on this already-too-large thread.

You were nothing other than the proverbial straw on an overloaded camel.

 

[fenderf4i]

I assembled an O2, had never done anything like this before. It passed all of the initial tests, and sounds great! I have 2 more on the way, then I will assemble a desktop version!

 

[xdanelliott]

If your AC adapter is good, there is likely a component oriented incorrectly or a solder bridge creating a short. Inspect the DC jack, diodes, capacitors, & regulators for a problem.

Checked everything and it looks good..

 

[sofaspud]

Measure the voltages in-to and out-of the regulators U5 and U6.
Since your O2 operates fine on battery power, the problem must be within the "Optional AC Power Supply" box in the schematic.

 

[ethanolson]

Just finished my first o2 Amp!
Works great from battery, however, when powered from the AC adapter wau12-200 there is a very loud buzzing sound and no music is playing.

Do you have the same problem when the front panel is removed? What about when the board is removed from the case?