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Old 13th December 2011, 02:37 PM   #1421
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Originally Posted by hbarradah View Post
I'm planning on running this using the batteries for most of the time. Puting the battery on the board, the wires are pretty much right on top of the batteries, may be 1mm over it. Is that ok? or will the batteries introduce noise into the pot cables?
Yes, that's fine and much better than running anything on the AC adapter side of the amp. Just make sure the pot/input/output wiring are twisted pairs. As mentioned in the article, pulling the pairs out of any sort of CAT5 ethernet cable works great. You can also twist together 30 AWG wire wrap wire.

Quote:
Originally Posted by Limp View Post
FQU17P06 for Pch and the Nch says FQPF10N20C. It's what was supplied with Jokeners kit.
I have now replaced both MOSFETs and all tests seem ok. I get ~250mV on the Low Voltage Shutdown test, but there is still very loud 'pop' when I turn it on.
If you don't have an oscilloscope I can only make "blind" suggestions. Make sure all the parts around U2 are the correct values and correctly soldered. Getting any of those wrong, especially C1, C16, C21, R4, R24, and R8, could make the turn on transient worse by "unbalancing" the circuit. I'm also assuming you didn't modify the amp in any way (use parts not on the BOM, etc.)?

This may sound weird, but try pushing the power switch in (with no front panel or just the bare board) at an angle from both the power jack side and from the volume control side and see if that makes a significant difference in the pop. Pushing it from the side will slightly rotate the sliding portion inside the switch. If one side of your switch is making contact much sooner than the other side that might make the transient worse. If so, you might have a marginal power switch.

You can also try making C1 smaller--say 0.1 uF or 0.22 uF but if it's too small, the amp may not turn on at all with partially discharged batteries and the transient associated with low battery shutdown might be worse. In my testing (see the scope photos in the O2 Details article) 1 uf was optimal.

With my amps, using "average sensitivity" headphones the turn on "tick" isn't very loud or objectionable. With my HD650's it's even softer. With my balanced armature IEMs, which are some 20+ dB more sensitive, the tick is more of a "pop" as it's 20+ dB louder.

What headphones have the loud pop?
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Old 13th December 2011, 05:18 PM   #1422
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Timpert, I am very interested in your guide. This is my first PCB board that I am soldering and I would greatly appreciate any help you can give. I was just going to go off my knowledge of soldering and looking at the pictures, but I know the current needs to flow between the pieces and I would vastly thank you for creating a step by step guide for people like me. I think it will help me a lot to take on future projects but I wanted to start with this Objective 2 Amp because it has awesome reviews and doesn't really look like a terribly hard thing to put together if I got all the right parts. So please if you have the time and energy make this guide. I think there will be a lot of people appreciative of this on here because it seems that tons of people have questions and it's their first or second project as well. I PM'ed you as well but I might even donate $5 to the guide if it's good enough. If I am allowed to do that I am not sure.
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Old 13th December 2011, 05:29 PM   #1423
oslpag is offline oslpag  Sweden
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Default Guide

I will happily do a guide as it is really a straight forward build, all the information is on nwavguy's blog, there is a lot of information on the site but if you read through carefully it is pretty simple.

If there is enough interest for me to do a guide then I will order some parts and build another O2 taking pictures etc on the way.

You will have to wait a couple of weeks though as I need to order the parts.
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Old 13th December 2011, 05:54 PM   #1424
timpert is offline timpert  Netherlands
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Okay, so I'll continue with the guide. I just wanted to make sure it is time well spent.
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Old 13th December 2011, 06:37 PM   #1425
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Two guides even better!!! The approaches will likely be different and that would be excellent for us noobs.
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Old 13th December 2011, 08:40 PM   #1426
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Quote:
Originally Posted by RocketScientist View Post
Just make sure the pot/input/output wiring are twisted pairs.
I twisted each channel together so I have 3 24AWG wires twisted together. Is that what you meant, or did you mean a pair for each tab on the PCB, so it would be 3 pairs per channel?
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Old 13th December 2011, 09:06 PM   #1427
MrSlim is offline MrSlim  Canada
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Quote:
Originally Posted by jschristian44 View Post
Timpert, I am very interested in your guide. This is my first PCB board that I am soldering and I would greatly appreciate any help you can give. I was just going to go off my knowledge of soldering and looking at the pictures, but I know the current needs to flow between the pieces and I would vastly thank you for creating a step by step guide for people like me. I think it will help me a lot to take on future projects but I wanted to start with this Objective 2 Amp because it has awesome reviews and doesn't really look like a terribly hard thing to put together if I got all the right parts. So please if you have the time and energy make this guide. I think there will be a lot of people appreciative of this on here because it seems that tons of people have questions and it's their first or second project as well. I PM'ed you as well but I might even donate $5 to the guide if it's good enough. If I am allowed to do that I am not sure.
You can donate to DIY Audio, like we all should ..
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Old 13th December 2011, 09:11 PM   #1428
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Finished first O2 few minutes ago...this is a monster! Currently I'm driving only from batteries but it has such stunning dynamics.

Thank you RS!
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Old 13th December 2011, 09:18 PM   #1429
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Two guides would be awesome, the more pictures the better as well. From what I can tell it's basically just soldering the parts on the board, but I know some parts need to connect to some hookup wires, etc that I am a little confused on. Thanks again!
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Old 13th December 2011, 10:03 PM   #1430
nezbleu is offline nezbleu  Canada
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Quote:
Originally Posted by jschristian44 View Post
From what I can tell it's basically just soldering the parts on the board, but I know some parts need to connect to some hookup wires, etc that I am a little confused on. Thanks again!
If you build the stock circuit using the BOM materials and put it in the recommended case, no wires are required.

Some folks are using different cases, different jacks, different layouts, so need some wires to make it all work.
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