[HolyCheese]

  I couldn't find a thread on the O2 in the DIY section so I'm just going to ask here.

So, I soldered together my own O2+ODAC a couple of months ago and everything works fine so far. However, there might be few small problems.

Because this was my first DIY attempt, I didn't honor the "put everything in shortest to tallest" rule too throughly, and the regulators (U5, U6) ended up being too tall, which can potentially short to the case. I've checked, and there is around 1mm of space between the top to the case, but it might touch the case if the amp is held upside down or if I apply pressure to the board.

I've tried heating up the joints to push the regulators down a bit, but I cannot heat all 3 joints on the regulator at the same time and the top of the regulator gets quite hot during soldering which makes it hard to push down.

Can any experienced DIYer tell me if this could cause a problem, and if so, how could I fix it?

 
Buy something called a solder sucker, or solder wick (goat wick) And make sure to let the IC cool down between attempts. I'm not sure how long you tried but if I recal correctly overly heating the IC's can damadge them.

 

[Xenophon]

You could try it as described above but be aware that there's a possibility that you'll fry the component (or in a worst case scenario the pcb).  I don't know what the component you're trying to insert deeper looks like so maybe the following is totally impossible but you might be able to cut off the leads going into the pcb, then heat the joints, remove the solder with a wick and resolder the shortened component (I had to do that after clumsily soldering a varistor once).  Or if electrical insulation from the top of the case is an issue and you can live with the rest, use goop and/or a piece of keratherm insulting pad between the component and the top of the case.  Not ideal and it won't protect against mechanical stress but you'll have excellent electric insulation and don't risk frying stuff.

 

[jseaber]

  I have a question regarding low volume listening. I almost Always listen at low volums with my x2's. ATM I'm listening to the lowest possible volume possible without channel imbalance at 1x gain.
 
Is it possible to set the gain at e.g. 0.5x?
Or would it be a better alternative to buy another volume pot without channel imbalance?

 
Minimum gain is 1.0x for most amplifiers, including O2. To de-amplify, you need another volume control. The volume control at your source should get the job done.
 
 

   
I saw your comment about USB cable with ferrites before (not sure if it's this thread). The measured difference is huge but was it tested to be audible against quality cable without ferrites? Can't seem to find any comment about it from Nwavguy's blog. Thanks

 
Good question. We're talking about the difference between 98dB and 108dB noise floor. I suspect you'd notice the difference with sensitive headphones. I'll have to experiment with the ears.

 

[Solrighal]

It's not easy to find a nice USB cable at a reasonable price with a ferrite bead. I can't find any.

 

[jseaber]

  It's not easy to find a nice USB cable at a reasonable price with a ferrite bead. I can't find any.

 
Pick any USB without a ferrite, then attach TDK p/n ZCAT2035-0930. This part is available at Amazon, eBay, Mouser, DigiKey, and works well.
 
For thicker cables, try p/n ZCAT2436-1330.

 

[snowlune]

   
Buy something called a solder sucker, or solder wick (goat wick) And make sure to let the IC cool down between attempts. I'm not sure how long you tried but if I recal correctly overly heating the IC's can damadge them.

 
Thank you for your advice. I've tried using wick (not too skilled with the solder sucker) but to no avail. When I try to desolder it, a bit of solder stubbornly remains inside the hole and the component is still stuck. I'm not sure if I'm just too inexperienced or my equipment is **** but I'm a bit paranoid about overheating and breaking something.
 

  You could try it as described above but be aware that there's a possibility that you'll fry the component (or in a worst case scenario the pcb).  I don't know what the component you're trying to insert deeper looks like so maybe the following is totally impossible but you might be able to cut off the leads going into the pcb, then heat the joints, remove the solder with a wick and resolder the shortened component (I had to do that after clumsily soldering a varistor once).  Or if electrical insulation from the top of the case is an issue and you can live with the rest, use goop and/or a piece of keratherm insulting pad between the component and the top of the case.  Not ideal and it won't protect against mechanical stress but you'll have excellent electric insulation and don't risk frying stuff.

 
Thank you for the reply. Yeah, it would be pretty sad to fry something and break my O2 which is working right now. About cutting off the leads and resoldering it, the O2's board is pretty clustered and the component at issue here is surrounded by other components that would make it a bit hard to cut. Also, I'm not sure whether the leads would be long enough after cutting to be soldered again.
 
About insulating the component from the top of the case, that is a good idea. I'm not sure if I can find that where I live. I'll use my multimeter to test some things like household paper and tape and try to find something I can use to insulate the component.

 

[JacobLee89]

   
Thank you for your advice. I've tried using wick (not too skilled with the solder sucker) but to no avail. When I try to desolder it, a bit of solder stubbornly remains inside the hole and the component is still stuck. I'm not sure if I'm just too inexperienced or my equipment is **** but I'm a bit paranoid about overheating and breaking something.

 
Out of curiousity, how did you use the wick?
 
The only method I know is placing the wick on top of part, and then placing the iron on top of the wick. I've read somewhere that solder likes to flow towards the hottest component.
 
Sometimes I pull on the wick gently when the solder starts soaking into the braid, and the solder sometimes get wicked along the length of material. I'm not sure if that's a recommended thing to do though.
 
Using solder flux also helps, but that's where my knowledge of "why" ends.

 

[HolyCheese]

@snowlune
Yea in this case I'd also suggest to just insulate it. Try using insulation tape. It's pretty thin and should do the trick. I'm not sure how it would be called in you country but the stuff usually comes in red, blue, and brown greenish colour, is rubbery and stretchy.
 
However i'm not sure what the best way to apply it would be. Since putting the tape all around the metal part might make it too hot?
 
If you have a hot glue gun (also not sure how you call this in english) you can also try to apply a little of this glue to the top of the IC. Make it some kind of hat. 
 
Only problem is that with alot of movement the glue gets loose after a while, so just leave it in the case and it should be fine.

 

[HotIce]

Desoldering multi-pin, through hole, ICs, is a PITA, if your plan is to save the IC. Especially for plated through holes, where solder sips in. I never solder through hole ICs directly and use sockets instead.
Given that replacing the OP-amp will not break your bank account, the safest way is to cut the pins, and then pull them one by one. Otherwise overheating might make more damages than the ICs cost. You might end up with detached solder pads/tracks, which is not where you want to be.
If you want to play with OP-amps rolling, I suggest to cut the pins, pull them one by one (at that point is easy - apply heat on bottom, pull pin with tweezers from up), and install sockets in there.

 

[Solrighal]

Pick any USB without a ferrite, then attach TDK p/n ZCAT2035-0930. This part is available at Amazon, eBay, Mouser, DigiKey, and works well.

For thicker cables, try p/n ZCAT2436-1330.

Thanks John, that's most helpful. Is there a reason why the ferrite bead always seems to be at the DAC end of the cable?

I'm also tempted to ask if you think I might be wasting my money but I suspect I already know the answer to that one. Even if it only looks better that would be enough, as long as the price is right.

 

[jseaber]

Thanks John, that's most helpful. Is there a reason why the ferrite bead always seems to be at the DAC end of the cable?

I'm also tempted to ask if you think I might be wasting my money but I suspect I already know the answer to that one. Even if it only looks better that would be enough, as long as the price is right.

 
There's a set of equations to answer this EMC question.
 
From my intuition (and emprical results), the ferrite is placed nearest to the receiving end to minimize EMI. Placing the ferrite at the opposite end would expose the majority of the cable length to interference before the signal reaches the receiving device. EMC is not my specialty. PhDs in the field may slap me.

 

[adydula]

The Ferrite bead at the dac end makes sense, it provides the "filtering or prevention" of any possible interference into the dac that "might" cause issues in the DACS functioning....that is tuning the bits into analog. I like to call these "ferrite chokes" instead of beads.....LOL.
 
I scoped several cables with and without ferrite beads and have not seen any real EMI or interference...I seem to have a clean environment.
 
Don't place your cell phones, VAC power cords etc near the cable....
 
Many are under $10
 
http://www.amazon.com/Monoprice-1-5-Feet-Mini-B-Ferrite-105446/dp/B003L18RZU/ref=sr_1_3?ie=UTF8&qid=1424109570&sr=8-3&keywords=usb+cable+with+ferrite
 
Heres one with ferrite chokes on both ends:
(now this has to "sound" better than a cable with only one "bead"!)

 
http://www.amazon.com/Tripp-Lite-Hi-Speed-Ferrite-U023-003/dp/B008VOPCGY/ref=sr_1_2?ie=UTF8&qid=1424109570&sr=8-2&keywords=usb+cable+with+ferrite
 
Alex

 

[snowlune]

   
Out of curiousity, how did you use the wick?
 
The only method I know is placing the wick on top of part, and then placing the iron on top of the wick. I've read somewhere that solder likes to flow towards the hottest component.
 
Sometimes I pull on the wick gently when the solder starts soaking into the braid, and the solder sometimes get wicked along the length of material. I'm not sure if that's a recommended thing to do though.
 
Using solder flux also helps, but that's where my knowledge of "why" ends.

 
I think normally I do the same thing. Sometimes I put a dab of solder on the iron so the heat transfers faster through the wick.
I need to buy some solder flux though....
 

  @snowlune
Yea in this case I'd also suggest to just insulate it. Try using insulation tape. It's pretty thin and should do the trick. I'm not sure how it would be called in you country but the stuff usually comes in red, blue, and brown greenish colour, is rubbery and stretchy.
 
However i'm not sure what the best way to apply it would be. Since putting the tape all around the metal part might make it too hot?
 
If you have a hot glue gun (also not sure how you call this in english) you can also try to apply a little of this glue to the top of the IC. Make it some kind of hat. 
 
Only problem is that with alot of movement the glue gets loose after a while, so just leave it in the case and it should be fine.

 
The insulation tape idea is smart. I could tape it to the top of the case. That way, I won't have to worry about the regulator melting the adhesive and creating a mess.
 
Hmmm, I'm not so sure about the hot glue gun.
You see, the part I'm having trouble with is not the IC, but the voltage regulators, which get a bit hot after use.
 
But the insulation tape idea is flawless, and I'll look into that. Thanks tons for the idea!

Desoldering multi-pin, through hole, ICs, is a PITA, if your plan is to save the IC. Especially for plated through holes, where solder sips in. I never solder through hole ICs directly and use sockets instead.
Given that replacing the OP-amp will not break your bank account, the safest way is to cut the pins, and then pull them one by one. Otherwise overheating might make more damages than the ICs cost. You might end up with detached solder pads/tracks, which is not where you want to be.
If you want to play with OP-amps rolling, I suggest to cut the pins, pull them one by one (at that point is easy - apply heat on bottom, pull pin with tweezers from up), and install sockets in there.

 
Hahaha, I guess I'm lucky that I'm not desoldering an IC, but the voltage regulator.
I could just try to cut them off and buy new ones but shipping to Canada is expensive

 

[HolyCheese]

Voltage regulator is an IC, right? ;p
Anyway, try the tape on the casing, maybe use some good glue that won't be affected by warmth.
 
 
Btw anyone still have some idea for the channel imbalance?

 

[HotIce]

Oh, sorry, I lost track and thought you were attacking the OP-amps.
The MC7912/7812 are just about $0.50, and you should be able to find them pretty much everywhere. Also, they are three pins inline,which would eventually make the disoldering operation much simpler.
Chip Quik is another solution, but it will end up costing you much more than the VRs.