The Objective2 (O2) Headphone Amp DIY Project

@Alexium: It is really easier than you think.
You start with the resistors and Diodes.
To find out what color codes on the resistors relate to what values, use an online tool.
The diodes are easy, just go by the quantity used.
Then the small caps (go by quantity, lead spacing and pictures... Mouser and Google are great).
Then the DIP-8 sockets and everything else, they should all be self-explanatory when consulting the PCB and the BOM.

Its really smooth sailing. I was surprised myself.

Best regards,
Jokener
 
CSA really is an insane person. ignore the troll :troll: he changes his story, changes his thoughts, changes his words; all in an effort to gain a reaction

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.
 
Alexium:

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

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

@ Jokener:

Construction might seem daunting, so people might get increased confidence from a step-by-step description, so that they actually see that it is not such a big deal before diving into the deep.
 
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CSA, et al., several years ago I used to get myself caught in "communication" traps and dug myself in deeper all the time trying to find stuff to back up my position. That tactic is best suited to talk radio. Now I just don't get emotionally invested in problems I'm trying to work out (including personal attacks) and things are much better because of it.

There's hope yet. Just give it time and realize the wisest among us are those who don't mind learning and taking correction even from the harshest of people.

I'd love to make changes to the O2 as well, but I don't know if any would make it "better." Better for more cost and complexity isn't always better, is it?! I personally would much prefer to have it built to run on 4 AA eneloop 1500 batteries. The power circuit would really have to change and maybe not for the better.There's only one way to find out.
 
Well this weekend I had a free moment and got my O2 working again!

I was completely wrong, the regulator was fine. I double checked the all solder joints and re-flowed any that looked suspect as well as all the components in the power section.

While I was examining the board, flipping it around under a magnifying glass I felt some odd rattling from the 3.5 mm output jack that. It was faint, you felt it more then you can hear it. I de-soldered it (a complete pain-in-the-rear) and replaced it with one I had in my parts bin.

Powered it up and it works again! At this point I'm going to sum it up as my stupid mistake, a weak solder joint that just happen to fail after a week of burn in. I should have triple checked re-flowed everything first before making outrageous presumptions.

Thanks to RS and everyone that offered their suggestions.
 
The only vaguely difficult part of the build for me was avoiding/fixing solder bridges when soldering the MOSFETS and regulators, but that is more testament to my ****-poor technique and the fact I decided not to invest in any desoldering equipment. Hence I had to get rid of the bridges by heating the solder and poking them with a cocktail stick! Worked surprisingly well, all things considered.

EDIT:mad:billyk: Not easily, I'm afraid. The O2 uses a dual-rail supply.
 
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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?
 
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.
 
@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.
 
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 :)

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 :)
 
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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;)
 
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?
 
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@ 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.