The Objective2 (O2) Headphone Amp DIY Project

[konga]

Can you have both the 3.5mm input jack and an external jack connected to P3? Would I need to cut the traces to ground as mentioned in the documentation.

I'm thinking I can maybe fit a pair of rca jacks in the rear of the b2 case next to the batteries.

[qusp]

Originally Posted by Willakan

Moving on from cheapskate (I think bothering with what he has addressed to me, what he has addressed to NwAvGuy and what he has said regarding the amplifier design is no longer worth anyone's time) I have enjoyed listening to my O2, which incorporates RCA jacks and a PCB-mount headphone jack (secured below with the finest audio-grade glue after I realised it wasn't going to go in any other way) into the front panel.

silver epoxy?

[Jokener]

The power circuitry in the O2 divides the AC up into two half-sine waves for each channel.
That would not be possible when supplying only one single DC current.
-> Major rework would be necessary to get it working on external DC.

Regards,
Jokener

P.S.: Please correct me if I'm wrong or talking nonsense.

[Alexium]

@Jokener: thanks! The color-coded resistors really drive me mad. Russians are simple people, they don't know colors, so they just spell the resistance with numbers Otherwise resistors are great once you have a DMM to measure them (I know it's not accurate, but provided I have the exclusive list of all the nominals used I hope I'll be fine).
P.S. On a sidenote, why use color-coding, anyway? I can only think of one advantage over plain simple numbers - it doesn't matter how you rotate the part, so you don't have to spend time aligning it when mounting. Am I missing something else?
Sorry for OT.

[Alexium]

Originally Posted by timpert

I have just started writing something like that. I think a first version should be ready after the weekend, to be reviewed here.

Thanks! I'll wait for it, then. I hope to participate review first-hand, so to speak

Originally Posted by timpert

I have just started writing something like that. I think a first version should be ready after the weekend, to be reviewed here.

Great! I'll wait for it, then. I hope to participate review first-hand, so to speak

[NicMac]

Originally Posted by Alexium

I was hoping someone has composed the instruction like "put the piece A into the hole B"

I stuffed it by looking at a good photo of a build unit. The 1/8W resistors are terribly small and I used a DMM to identify these. If you got the component kit from Jokener there are actually many more resistors than you will need (for freedom in choice of gain). The placing of all other component can readily be identified by their footprint.
Cheers,
Nic

P.S. Really sings with my HD650 and not running hot

[Jokener]

Well... russian technology, american technology... nowadays its all from Taiwan anyway ^^
(free translation of a semi-decent movie-quote)

[qusp]

Originally Posted by cheapskateaudio

I change my thoughts, my words, my story? Why does this make one insane? Things change, new ideas, new facts, these things adjust perception, unlike you I'm trying to find the TRUTH, and not live according to DOGMA like some folks around here who get all kerfluffled when their dogma is challenged.

not on the same page it doesnt, changing your story of your view of the amp on the previous page of this thread from a good value and nice sounding amp that needs a single compensation cap; to a pile of junk you had to 'fix' to make it rise from the level of vaguely musical rectal murmurings for dramatic effect makes you either a troll or a genuine insane person, which would you prefer?

[Alexium]

@NicMac: it didn't occur to me... Great idea! Would you advise any specific picture?

[cheapskateaudio]

Originally Posted by Jokener

@ CSA: 50€'s say you are making stuff up!
I just recently assembled my first own O2 after sending out all the kits for people in the GB.
It was built using a cheap, unregulated soldering station built BEFORE the last war (and I live in Germany, we don't have many wars around here) by someone (me) with mediocre (at best) soldering skills.
I have successfully used it to drive a Medusa headset (more power hungry than HD650), a few HDXXX series headphones, my Shure SE530 cIEM's and a few others, all without problems.

But I am prepared to put my money where my mouth is.
I am offering you 50€ (which is more than the parts cost) for your bad sounding O2.
And when I get it, I will put it up and measure it against a few of my own O2s I will have built by then.
And I will publish the results here and on Head-Fi ( -.- ) to show what was really wrong with your O2.

Your turn!
Do you fold and give up?

I will ship you my modded amp for 80 euros. I'll be sure to wrap it in an anti-static bag and it will be well padded. I'll include the hammond case for 15 euros more, I won't need that one as I have a boxenclosures case with a front panel. I've got a second FPE (front panel express) file done for the hammond enclosure that I can send if you decide to get that box. Though I'm not sure if FPE ships to europe.