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-   -   The Objective2 (O2) Headphone Amp DIY Project (http://www.diyaudio.com/forums/headphone-systems/193977-objective2-o2-headphone-amp-diy-project.html)

availlyrics 4th February 2013 06:17 AM

You don't scare me:)
Actually, I forgot to order them :o & only the ordinary ceramic types are available locally. I dont want to wait for another 15 days for it to arrive.
I'm more concerned from ckt. stability point , thankfully I donít have golden ears to diff. between various capacitors.BTW I've read somewhere that SMD ceramic cap. are C0G only

qusp 4th February 2013 07:28 AM

C0G/NP0 have better Tempco and Voltage coefficient. C0G vs X7R or less, generally C0G are made to a higher quality and can cause lower distortion due to the second factor. they are critical for timing and compensation circuits and have measurably lower THD depending on where they are used. no golden pinea arguments here, very objective.

but no, not ALL SMD caps are C0G, not in the slightest

availlyrics 4th February 2013 09:32 AM

Quote:

Originally Posted by qusp (Post 3355126)
.
...but no, not ALL SMD caps are C0G, not in the slightest

That cleared my doubts

ramsfan6239 5th February 2013 02:45 PM

I have a problem with my o2 amp,

I tried it with several sources, and each one gave the same result. The light comes on but there is no sound when the unit is switched on with battery power only. If you either start it on wall power and then remove the wall power, or start on battery power and then plug in wall power and remove it, then it runs fine on battery power. The key here is that it will run fine on battery power as long as it has been plugged into wall power, even for a moment, sometime after the power has been cycled. I can't see how any flaw with my several audio sources or a flaw with the batteries (I did try another set of known good batteries, by the way) could cause this strange behavior. I'm guessing that it might have to do with the power control circuit.

Any idea on where I should troubleshoot?

6L6 5th February 2013 02:53 PM

Please post well-lit, in-focus photos of your PCB from a few angles. That will help us immensely.

You will be amazed at what some people can spot on a photo!! :)

jtktam 5th February 2013 05:58 PM

Quote:

Originally Posted by ramsfan6239 (Post 3357015)
I have a problem with my o2 amp,

I tried it with several sources, and each one gave the same result. The light comes on but there is no sound when the unit is switched on with battery power only. If you either start it on wall power and then remove the wall power, or start on battery power and then plug in wall power and remove it, then it runs fine on battery power. The key here is that it will run fine on battery power as long as it has been plugged into wall power, even for a moment, sometime after the power has been cycled. I can't see how any flaw with my several audio sources or a flaw with the batteries (I did try another set of known good batteries, by the way) could cause this strange behavior. I'm guessing that it might have to do with the power control circuit.

Any idea on where I should troubleshoot?

the batteries are out of sync, if you have a standalone 9v charger, then take out of the o2 and charge them to full.. once you do that and put them back into the amp, it will work correctly..

next time don't run the battery down to a level where they are uneven

-joe

ramsfan6239 5th February 2013 09:23 PM

Quote:

Originally Posted by 6L6 (Post 3357031)
Please post well-lit, in-focus photos of your PCB from a few angles. That will help us immensely.

You will be amazed at what some people can spot on a photo!! :)

I will do that in a moment!

Quote:

Originally Posted by jtktam (Post 3357245)
the batteries are out of sync, if you have a standalone 9v charger, then take out of the o2 and charge them to full.. once you do that and put them back into the amp, it will work correctly..

next time don't run the battery down to a level where they are uneven

-joe

Both batteries are fully charged - Tested with a multimeter at 9.2 ish volts, and there is maybe a tenth of a volt between the two.

ramsfan6239 5th February 2013 09:27 PM

ramsfan6239's Library | Photobucket

There are a bunch of photo's, they will be the first 6 or so. If you need me to take more let me know.

-Tyler

WildChinoise 6th February 2013 11:58 PM

Wow! I stumbled upon this one a few days ago and have read all 3000+ messages. Kudos to the great support you are lending to each other and to the newbies that are asking for help. I'll be one of those fellows in a month or so after I clear some other items off my desk first.

And especially thanks to the RocketScientist for the great effort he put in!

Bassd 8th February 2013 03:27 AM

Hi guys, new to DIY. I ordered the kit from headn'hifi, I know how to solder and have all the right tools. BUT I can't work out how to sort and label all the parts I got and match them with the reference numbers on the BOM.

main problems is the tiny resistors. Do I really have to look at each color code and slowly decipher them? Only problem there is the resistors seem to have 5 stripes and i'm not sure how you tell which end to start at.

Sorry for the novice questions


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