Here are a few tips to get you started:
Print out the Documents package from NwAVGuy's site. The board layout with the parts labelled on it helps a lot.
Use the BOM (Bill of Materials) spreadsheet to upload the parts list to Mouser directly. (or PM ,me for my copy of a Mouser Project that is already input and ready to order).
Print out the "Testing Procedure page".
When you get the parts order, Mark the part # (R1 D1, etc) on the part bag label. Then stuffing the board is like paint by number.. (Part by number?..
) Start with the smallest/lowest profile parts first and work up to the larger ones.
Some parts need to be oriented the correct way, some don't care:
Resistors can go in either way. Any capacitors (the C# parts) without + or - markings on them can go in either way as well.
The big "can" capacitors need to go in the right way. The negative wire is marked on the cans. Pictures of Completed boards can also help to figure out orientation.
Diodes(D#) are marked with a thick line on one end. Match that end up with the thick line on the D locations.
The Q and U parts (MOSfets and Regulators) backs are marked with a thick line on the board. This is the heatsink or Flat side on them(look for exposed metal, although one of the MOSFets is all plastic, if you compare it to one of the Regulators(7812), you can tell which side is the "heatsink" side.
Orient the IC sockets (U1-U4) according to the little cutout on the board layout. Pin 1 on the board is marked by a white dot, and a square printed circuit pad. Match this with the pin with the dot beside it on the actual IC itself..
It is mentioned in NwAVGuy's build document, but it's worth mentioning here too: There is a "via" (a hole that is used to connect the circuit between sides of the board but not connected to anything else) that is between S2 and R21 that is very close to one of the "standoff legs" of S2. Put S2 in temporarily before soldering anything else and you will see that the via can touch(or is very close) one of these legs. Bend or remove that leg on S2 itself. It has caused a few people some grief.
Also, cut the little Tab off the front of VR1 before you install it.. (also mentioned in the Blog).
Could you expand on that? For example what do you mean by 'not blown away"? Was the audio quality no better than a mini3? Did you hear noise? Distortion at higher volume levels? What are you comparing it to, particularly in reference to price/performance?
What amps would you say are superiour and why? What do they do that the O2 doesn't?
What did you find decent about the amp?
I also have to question if one should be "blown away" by an amp. In essence an amp should be as transparent as possible. We've all heard the saying "garbage in garbage out". Perhaps you were just hearing the source as it really is when nothing is added or taken away by the amp.
We've all heard the saying "garbage in garbage out". Perhaps you were just hearing the source as it really is when nothing is added or taken away by the amp.
How true! When I built my first O2 amp I fed it initially with the headphone output on my Sony laptop. Yuk, no bass. Then I fed it via an optical link DAC from the same laptop and wonderful sounds ensued with plenty of bass.
Nothing changed with the amp of course. Just two different sources doing their thing.I built this amp all stock except MKT181 mouser caps (semi audiophile approved, I listen to Grados and frankly stock Grados weren't sounding very good, probably because to much damping, Joe tuned Grados to a hybrid with huge ugly distorion pattern (melos). Probably the drivers cancel some of the amps distortion in much the way the O2 uses heavy NFB to distort the incoming signal in order to cancel out the distortion on the output.
However, I tried this amp with a pair of Magnums which are Grados with a driver designed in 2011 instead of 2001. And the results were stunning, detail like I never imagined possible with these style phones.
I hate to say this but NwAV guy is simply adding huge amounts of distortion to cancel the non-linearity of the opamps, the NFB works and the output is low distortion. But because headphones are non-linear themselves headphone amp builders have been doing a similiar thing just including the headphone in the loop.
Its an interesting thing and certainly a very good amp, but purists should look at the distortion at pin 6 and 2 of each audio opamp and look at all the color being added to the input in order to get a low distortion output.
There is a whole lot of color added to the input of this amplifier, a whole lot.
And I am glad, it sounds good with fairly linear headphones.
, I listen to Grados and frankly stock Grados weren't sounding very good, probably because to much damping, Joe tuned Grados to a hybrid with huge ugly distorion pattern (melos). Probably the drivers cancel some of the amps distortion in much the way the O2 uses heavy NFB to distort the incoming signal in order to cancel out the distortion on the output.However, I tried this amp with a pair of Magnums which are Grados with a driver designed in 2011 instead of 2001. And the results were stunning, detail like I never imagined possible with these style phones.
I hate to say this but NwAV guy is simply adding huge amounts of distortion to cancel the non-linearity of the opamps, the NFB works and the output is low distortion. But because headphones are non-linear themselves headphone amp builders have been doing a similiar thing just including the headphone in the loop.
Its an interesting thing and certainly a very good amp, but purists should look at the distortion at pin 6 and 2 of each audio opamp and look at all the color being added to the input in order to get a low distortion output.
There is a whole lot of color added to the input of this amplifier, a whole lot.
And I am glad, it sounds good with fairly linear headphones.
I know its just that NFB has had bad wrap, the implementation here works wonderful.
But those that say the O2 doesn't add distortion, have it backwards, it works by adding a ton of distortion to the input so it is cancelled by the output. An argument can be made that this cancelling is best left to the headphones or the ears starting with a more linear amplification.
But I like to hear all methods, and this O2 is a very very good one with the right headphones IMHO..
When judging a headamp, I'm like the rest and speak in terms of net effect. From that perspective it's acceptable to claim vanishingly low distortion from the O2. I'm also quite surprised at how well the O2 works with low impedance loads. Many headphone amps have much more residual distortion into low impedance loads (<=32 Ohms).
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Yep, it's the output that counts. (Simple "black box" approach.) The amp could have elves dances inside - who cares.
BTW, Benchmark Media's John Siau claims that 0-ohm outputs result in lowest driver distortion. On the other hand, the whole "current drive" thing started with exactly the opposite premise. I have no clue who's right - but wouldn't be surprised if the answer were "it depends". Or 42.
BTW, Benchmark Media's John Siau claims that 0-ohm outputs result in lowest driver distortion. On the other hand, the whole "current drive" thing started with exactly the opposite premise. I have no clue who's right - but wouldn't be surprised if the answer were "it depends". Or 42.
Hello there, so yesterday I finished my O2 and it was working great.
Sadly, this afternoon it stopped working properly : the left channel is OK I think, but the right channel is *heavily* distorted on both gain settings. I'll try swapping U3 and U4 as advised in the troubleshooting section of the blog and I'll report back, I just hope I've not fried one of them...
I'm sad because the amp was working so great yesterday... Listened through it for 5h without an itch...
Sadly, this afternoon it stopped working properly : the left channel is OK I think, but the right channel is *heavily* distorted on both gain settings. I'll try swapping U3 and U4 as advised in the troubleshooting section of the blog and I'll report back, I just hope I've not fried one of them...
I'm sad because the amp was working so great yesterday... Listened through it for 5h without an itch...
@Shamharoth, I would expect a U3 or U4 problem, or perhaps a bad solder connection somewhere that took a while to show up. You should should check for DC on the output and not use good headphones if you're hearing distortion.
@sgrossklass, the "current drive" thing is mostly creative marketing and myth. John Siau and I have shown the objective measurements that support our claims. There's also a lot of hard science, math, AES published papers, etc. on our side.
Those advocating higher output impedance and/or other "creative" output designs have virtually nothing supporting their claims. They don't have any credible measurements or blind listening tests. While it's certainly possible some might prefer the generally less accurate sound of some headphones driven from such a source, it's really hard to make an objective argument it's better overall. And both John and I have shown how it's generally worse.
@Everyone Else, Happy New Year!
@sgrossklass, the "current drive" thing is mostly creative marketing and myth. John Siau and I have shown the objective measurements that support our claims. There's also a lot of hard science, math, AES published papers, etc. on our side.
Those advocating higher output impedance and/or other "creative" output designs have virtually nothing supporting their claims. They don't have any credible measurements or blind listening tests. While it's certainly possible some might prefer the generally less accurate sound of some headphones driven from such a source, it's really hard to make an objective argument it's better overall. And both John and I have shown how it's generally worse.
@Everyone Else, Happy New Year!
Hello there, so yesterday I finished my O2 and it was working great.
Sadly, this afternoon it stopped working properly : the left channel is OK I think, but the right channel is *heavily* distorted on both gain settings. I'll try swapping U3 and U4 as advised in the troubleshooting section of the blog and I'll report back, I just hope I've not fried one of them...
I'm sad because the amp was working so great yesterday... Listened through it for 5h without an itch...
I'd check the solders all over the place. My first stop would be R12. Once all those are checked over and taken care of, I'd look at changing out U3.
I hope you used the right flux. Otherwise you may have continual problems arising in the future.
Good luck.
Hello there, so yesterday I finished my O2 and it was working great.
Sadly, this afternoon it stopped working properly : the left channel is OK I think, but the right channel is *heavily* distorted on both gain settings.
Have you made the modification on the gain switch yet? From here:
http://www.diyaudio.com/forums/head...headphone-amp-diy-project-14.html#post2774393
my jds labs O2 arrived today. I dont think i could be any happier with it. It really sounds better than i anticipated.
At this rate, my soon to arrive Cavalli Audio Stacker II is gonna have to learn to massage my shoulders to justify its cost ;-)
Hopefully i'll be able to DBT between the two. If for no other reason than to get an honest impression of which one i prefer.
At this rate, my soon to arrive Cavalli Audio Stacker II is gonna have to learn to massage my shoulders to justify its cost ;-)
Hopefully i'll be able to DBT between the two. If for no other reason than to get an honest impression of which one i prefer.
So I didn't end up making one, it seemed like a costly venture. I bought one from JDSlabs preassembled and bought an enclosure from Drillspot.com (b2-080).
Do I just insert the PCB board in, and that's it? The enclosure is metal so do I need to line it with foam or anything like that? So far I have a JDS board, front panel, enclosure and charger. seems like I've covered all necessary components yes?
Do I just insert the PCB board in, and that's it? The enclosure is metal so do I need to line it with foam or anything like that? So far I have a JDS board, front panel, enclosure and charger. seems like I've covered all necessary components yes?
Some random thoughts...
1. Make sure you get the box flipped around correctly - I didn't at first.
The top is the side with the two rows of groves etched into it. It matters since the PCB sits differently in the bottom slot.2. Slide the PCB in carefully in the bottom slot and take note of how close any of the solder connections or leads are to the metal under the slot as the board goes in. Trim as appropriate if anything looks too close. No foam or anything needed.
3. You may want to tap the holes first on both the front and back rather than use self-tapping screws. There is a discussion in the front panel group buy thread of the merits of pre-tapping the holes you might want to read.
4. A ground wire should be connected between the ground pin of the input jack and the box. Search through RocketScientist's essay here for the words "B2-080 Enclosure Ground"
NwAvGuy: O2 Details
Some random thoughts...
1. Make sure you get the box flipped around correctly - I didn't at first.
2. Slide the PCB in carefully in the bottom slot and take note of how close any of the solder connections or leads are to the metal under the slot as the board goes in. Trim as appropriate if anything looks too close. No foam or anything needed.
3. You may want to tap the holes first on both the front and back rather than use self-tapping screws. There is a discussion in the front panel group buy thread of the merits of pre-tapping the holes you might want to read.
4. A ground wire should be connected between the ground pin of the input jack and the box. Search through RocketScientist's essay here for the words "B2-080 Enclosure Ground"
NwAvGuy: O2 Details
Hey thanks for this. Okay so good call about the top/bottom. I'll definitely look out for this. Regarding the screws, my enclosure came with 2 different sets and the torx screws are the ones that fit. I just screwed them in and they are tapped now I think. Unless I'm missing something on how to tap the holes properly. Harhar
regarding #4, to clarify, I have to solder a wire from that input pin and make it like a hook (pictured) so it comes in contact with the front panel?
Wouldn't that make a small gap between the front panel and the enclosure? Can't I just make a smaller curl and stuff it into that hole where the screw goes in?
Where do I solder? I bought the preassembled PCB cause I never soldered a thing in my life, it would be a real shame to have to mess up the entire board cause i messed up one solder point. lol