The clicks and pops at power on and off aren't that loud even with my Shure SE530s which are very sensitive so it should hardly be "deafening" with the less sensitive Coppers or Magnums.
It sounds like there's something wrong with it to me.
I currently have my O2 sitting next to me, and I am very much enjoying it. That aside, I am having issues that prevent me from running my O2 off of battery power.
The amplifier runs fine from the wallwart, nothing gets hot, no audible clipping or distortion, etc.. I do get between 13.0 to 11.6 volts on pin 8 and the inverse on pin 4 of u3 and u4. The surplus voltage does not seem to be a problem, and it is the only voltage issue I have when running from the wallwart.
Running the amp from batteries, however, nets me 9.1 Volts on both output channels (measured from p2).
The batteries are Tenergy 200mAh batteries as specified in the BOM. I have checked the board as best I can for bridges, and so far I have found none.
Is this an issue stemming from damage to u5 and u6, or do I have a bigger problem?
The amplifier runs fine from the wallwart, nothing gets hot, no audible clipping or distortion, etc.. I do get between 13.0 to 11.6 volts on pin 8 and the inverse on pin 4 of u3 and u4. The surplus voltage does not seem to be a problem, and it is the only voltage issue I have when running from the wallwart.
Running the amp from batteries, however, nets me 9.1 Volts on both output channels (measured from p2).
The batteries are Tenergy 200mAh batteries as specified in the BOM. I have checked the board as best I can for bridges, and so far I have found none.
Is this an issue stemming from damage to u5 and u6, or do I have a bigger problem?
When building my O2, I accidentally singed C15 while correcting a mistake. One corner is now no longer a corner and more of a melted mess.
Do capacitors have a state between "fully working" and "fully broken", and what would the impact of a damaged/broken C15 be?
The various tests measured OK on the multimeter and the amplifier appears to function perfectly, but I'd rather be sure some non-obvious problem isn't going to blow things up.
A picture:
Do capacitors have a state between "fully working" and "fully broken", and what would the impact of a damaged/broken C15 be?
The various tests measured OK on the multimeter and the amplifier appears to function perfectly, but I'd rather be sure some non-obvious problem isn't going to blow things up.
A picture:
@Tawz
U5 and U6 should not affect battery power at all, and since you can run from a wallwart it would appear that the regulated part of the power supply is functioning correctly. Full battery voltage on the outputs is definitely a problem though. I can't think of anything specific... I'd pull the chips U1, U3,U4 and attack it again with an ohmmeter and a magnifier.
@nurulwai
Your C15 is fine. It doesn't appear that you compromised the capacitor innards in any way. It's just a cosmetic defect.
The answers to your questions are: yes; and shorted - a nonfunctioning O2, open - a noisier power supply. It's a bypass cap for the power supply.
U5 and U6 should not affect battery power at all, and since you can run from a wallwart it would appear that the regulated part of the power supply is functioning correctly. Full battery voltage on the outputs is definitely a problem though. I can't think of anything specific... I'd pull the chips U1, U3,U4 and attack it again with an ohmmeter and a magnifier.
@nurulwai
Your C15 is fine. It doesn't appear that you compromised the capacitor innards in any way. It's just a cosmetic defect.
The answers to your questions are: yes; and shorted - a nonfunctioning O2, open - a noisier power supply. It's a bypass cap for the power supply.
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Everything seems to be working.
Volume attenuation works on both channels.
Output voltages are well below 1v. The max voltage with a battery removed was .68 on p4 off U4.
Voltage at Batteries is closer to 11.6 than 11.8, and when I expect 11.8 at any voltage measurement I see 11.6.
I am getting a pretty loud click and thump at turn on and off with volume full down. HD597s and HD518s
Measuring close to
AC, on, no batteries for U2
1=-11.7
2=-8.8
3=-10
4=-11.7
5=-10
6=-11.7
7=8.5
R25 codes are something like (blue body) brown, dark-green, dark-blue/black, light-green, purple
Anything to worry about, or am I ready to sit back and enjoy?
Volume attenuation works on both channels.
Output voltages are well below 1v. The max voltage with a battery removed was .68 on p4 off U4.
Voltage at Batteries is closer to 11.6 than 11.8, and when I expect 11.8 at any voltage measurement I see 11.6.
I am getting a pretty loud click and thump at turn on and off with volume full down. HD597s and HD518s
Measuring close to
AC, on, no batteries for U2
1=-11.7
2=-8.8
3=-10
4=-11.7
5=-10
6=-11.7
7=8.5
R25 codes are something like (blue body) brown, dark-green, dark-blue/black, light-green, purple
Anything to worry about, or am I ready to sit back and enjoy?
How about a proper speaker amp...
Sorry, but its a headphone amp.. not a speaker amp.. people need to stop trying to make it into something it's not..
Wow! Pretty good job cramming all that in there... Those aluminium enclosures are rather nice... The ODAC should only be a month or so away and if the O2 is used as a yard stick, it should be a nice performer.
It will be interesting to hear the ODAC - will probably build one for fun, if nothing else.
My setup suffers a very small amount of noise and there is a sweetspot on the 25K attenuator where the noise is all but gone. maybe that can be improved. This is my portable system along with a netbook loaded with 200G of FLAC files.
It compares pretty well to my B4 preamp/AK4396 combo.
My setup suffers a very small amount of noise and there is a sweetspot on the 25K attenuator where the noise is all but gone. maybe that can be improved. This is my portable system along with a netbook loaded with 200G of FLAC files.
It compares pretty well to my B4 preamp/AK4396 combo.
Can't tell from your photo but is the body of the potentiometer connected to ground... I had a similar issue with my Wire using a near identical case & Alps RK27 pot', grounding the pot was the first recommedation I got and it worked 100%.
Of course if you've already done that then??? Though it does sound like it's a grounding issue.
I need to copy my CD's to HDD, the O2 & Odac should make for a very nice tranportable rig
Of course if you've already done that then??? Though it does sound like it's a grounding issue.
I need to copy my CD's to HDD, the O2 & Odac should make for a very nice tranportable rig
Is there a way to tell given an output V for my source and my headphones specs if the O2 will clip at gain level X, Y, etc.? I did some calculations using that spreadsheet that's floating around and it looks like I need a gain of 3.2 for my source (2.16 V) and my headphones (DT880 600 ohm).
Looks good! The big thing to check is DC offset voltage on the headphone output jack. Can also do it on P2. Just make sure that with the amp power up and nothing plugged into the input jack you only have 3-6mV (0.003Vdc) or so on the left and right channels. If that is OK then enjoy some music!
On the on/off popping, no idea. That is one for RocketScientist.