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Alien DAC v1.1 Construction Thread - Page 64

post #946 of 1560
11/1/07 at 11:45am
Quote:
Originally Posted by joneeboi View Post
I, too, have Alien DAC woes. First, the MAX, then the Alien. Oy, va voy. The LED lights up, the test points give me the 3.3V and 4.7V I'm looking for. What more do I need to do? Admittedly the SMD soldering looks terrible, but I reflowed everything to make sure. C32 I think might be a little messed up (almost completely ripped its soldering stuff off), not to mention I lost C31 and paralleled two 47nF caps (those ARE 47nF right?). I didn't know if it was touching the ground pad so I just wired it to G2.
Hi, I am sure no one has commented on your post because the soldering is quite obviously messy and you also did not clean up the flux left by the solder. Cleaning is quite critical for this DAC, indeed for most projects. Try cleaning with some alcohol until the board is cleared of the splashed solder and flux.

I am sorry for being so frank but that's how my work looked too, when I first started doing DIY. So, I am sharing the lessons I learned.

When re-flowing solder joints, I find it useful to dip the iron tip into flux paste before touching it to the solder. Of course the extra flux need to be cleaned up later.

Regards
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post #947 of 1560
11/1/07 at 1:38pm
Yeah it is an atrocious job, but I've been cracking my knuckles for the past 10 years and my hands are crazy wobbly. It almost looked like I was wired on (fill in those speeding up-type drugs here) when I was soldering some of those itty-bitty resistors on. I'm just lucky I didn't lose anything other than the C31.

As for cleaning up the flux, is it customary to clean up the board before the project is actually done? I understand flux can be generally corrosive and is pretty unsightly and ...unscently(?), but I figured why bother if it doesn't end up working? Unless you're suggesting it might work if I clean it up, then I'll jump right on it.

Thanks for the help, guys. I will get on on that when I can.

PS: that picture is funny to me, Tom. It doesn't make sense why it would be funny, but I like its bluntness. NO. YES. Muahaha!
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post #948 of 1560
11/1/07 at 2:07pm
Quote:
Originally Posted by joneeboi View Post
Yeah it is an atrocious job, but I've been cracking my knuckles for the past 10 years and my hands are crazy wobbly. It almost looked like I was wired on (fill in those speeding up-type drugs here) when I was soldering some of those itty-bitty resistors on. I'm just lucky I didn't lose anything other than the C31.

As for cleaning up the flux, is it customary to clean up the board before the project is actually done? I understand flux can be generally corrosive and is pretty unsightly and ...unscently(?), but I figured why bother if it doesn't end up working? Unless you're suggesting it might work if I clean it up, then I'll jump right on it.

Thanks for the help, guys. I will get on on that when I can.

PS: that picture is funny to me, Tom. It doesn't make sense why it would be funny, but I like its bluntness. NO. YES. Muahaha!
You have to find the right time of the day. My hands shake, too, but I try to find a time of the day to set aside where I think I'm laid back enough to do some good soldering on the Alien. Most of the time, that's early in the morning on a day I don't have to go to work, but if you tied one on the night before, that might not be a good time, either.

Seriously, you are not alone in that feeling. There are many times I don't hesitate to work on a through-hole board, but wouldn't even consider messing with the Alien.

Pick your spot in a day and time of the week, have everything laid out and organized, and then try to chill. It helps me, anyway.

EDIT: Heck, you didn't have any trouble taking some of the closest macro shots I've seen of this and your MAX. Even if you had it on a tripod, you still had to concentrate and get things positioned just right. So, you've got the touch you need - you just need to learn when.
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post #949 of 1560
11/1/07 at 3:31pm
Quote:
Originally Posted by joneeboi View Post
...

As for cleaning up the flux, is it customary to clean up the board before the project is actually done? I understand flux can be generally corrosive and is pretty unsightly and ...unscently(?), but I figured why bother if it doesn't end up working? Unless you're suggesting it might work if I clean it up, then I'll jump right on it.

...
indeed, cleaning up the board can produce immediate results. i've never had this happen in my limited experience, but flux CAN conduct electricity, and it's possible for such "flux bridges" to create problems. personally, i'd first heed Tom's advice and slather most or all of those globby looking joints with flux paste (this is a bit of an exaggeration - you really don't have to apply TOO much flux to get a joint to reflow well) and reflow them again so that you're more confident in the contact they're making with the pads below. reflowing in the presence of ample flux will also clear most solder bridges, if any actually exist. there's no point in cleaning before you do this, because the flux paste will melt all over the board and create a nice thick layer of goop.

once that's done, and you're confident in all those joints, you'll probably have done MOST of the soldering you'll do on the board, so it's worth giving it a good cleaning. if you have to do further work, it will probably be isolated to specific components, and you can use an alcohol-wetted Q-tip to do some spot cleaning. if the re-flowing and cleaning works, however, you won't have to do any more tinkering - cross your fingers!
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post #950 of 1560
11/1/07 at 9:57pm
Quote:
Originally Posted by tomb View Post
I bet!!

Good thought - something I've always repeated should be done, but I cased mine up in those Penguin mint tins too quickly. I'm waiting to build another one before trying this.

I'm not sure I completely agree that Dsavitsk's findings scale up, though - the Sonicaps remove a bit of that outstanding slam in the ES's on the MAX. It definitely opened up the highs and brought in the airiness and soundstage (but not in the cathode bypass position - Yuck!), so it maybe an OK tradeoff, maybe not - my opinion still runs a bit back and forth.

It's possible that the size ratio of the ES caps with the 0.22uf Sonicaps is so much closer in the Alien that the bass isn't affected. What happens in the MAX is that the Sonicaps are so much faster that they may overwhelm the giant (by comparison) 1000uf and 470uf ES's. The smaller 33uf ES's in the Alien (the size I got to fit) may be quick enough compared to the Sonicaps that the combination works much better.
trust me on this one, theres no loss in the low end with the ES's bypassed in the aliendac, how much the ratio between the 47uf and .22uf caps plays into that i'm not sure, but i would agree with you that theres something different when it comes to the tube bypass over the output bypass, but it follows dsavitsk's findings as far as i can tell.

anyways, i'll be able to compare it to a BG capped alien in a week or so, but it'll be a little skewed as this current alien is running at 5.5v and the BG config will be running off regulated USB power
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post #951 of 1560
11/2/07 at 11:15am
i just finished building my first alien last night (kit from jeff), i had no experience with SMD prior to this project. Reading the SMD tutorials made me really scared 'cause the guides made it sound so hard. but the DAC worked right after i finished soldering everything. i ran it for 2 hours from my powerbok G4 12". sound great... though its a bit too crunchy for my taste.. but maybe it will smooth out after a bit more burnin.

I'll put up some pics later .
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post #952 of 1560
11/5/07 at 4:50pm
Tomb or anyone else, I've read through this complete thread today since I am ready to finally build my Alien. Has anyone built the Alien without CL/CR? Wouldn't this work fine with amps like the soha and max? If so, what's the benefit in adding them, just to change the sound signature?

Thanks
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post #953 of 1560
11/5/07 at 5:44pm
Quote:
Originally Posted by Slaughter View Post
Tomb or anyone else, I've read through this complete thread today since I am ready to finally build my Alien. Has anyone built the Alien without CL/CR? Wouldn't this work fine with amps like the soha and max? If so, what's the benefit in adding them, just to change the sound signature?

Thanks
These are output caps from the DAC, without them, you see about 2.5V of DC on the output of the DAC. If you don't handle this DC before you amplify it, you might damage the amp (depending on the amp - solid state amps you're looking at the opamp being damaged with this much DC, I'm not sure about tube amps), but even if you don't damage the amp, you'll fry your headphones after the DC gets amplified. This might be prevented with output caps as in the SOHA and MAX, but as far as I know, you still need to handle DC voltage before amplification.

Basically, you need either output caps on the DAC or input caps on the Amp.
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post #954 of 1560
11/5/07 at 6:04pm
Thanks for the explanation, that makes sense. Making my BOM now.... I am sure Ill report back with something I screwed up
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post #955 of 1560
11/5/07 at 6:25pm
I bypassed CL/CR on my Alien per the suggestion of Dougigs on the headwize forum: http://headwize.com/ubb/showpost.php...61969&fpage=39

This mod is specifically for running the DAC into an amp that has its own method of DC protection (in the CK²III's case, the servo). Unless you're positive that your amp has a similar method of protection, I wouldn't bypass them; the negligibly small improvement in quality would not be worth the worry, in my view.
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post #956 of 1560
11/5/07 at 8:34pm
Quote:
Originally Posted by MoodySteve View Post
I bypassed CL/CR on my Alien per the suggestion of Dougigs on the headwize forum: http://headwize.com/ubb/showpost.php...61969&fpage=39

This mod is specifically for running the DAC into an amp that has its own method of DC protection (in the CK²III's case, the servo). Unless you're positive that your amp has a similar method of protection, I wouldn't bypass them; the negligibly small improvement in quality would not be worth the worry, in my view.
FWIW, you didn't "bypass" the caps, you just didn't include them... bypassing is when you parallel a larger capacitance cap with a smaller capacitance one, so that the smaller cap will pass high frequency signals that the larger cap might tend to roll off. people have certainly played with bypassing the output caps on the Alien - i know that Tom has talked about bypassing his 33uF Muse ESs with 0.22uF Sonicap Gen IIs with nice results.
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post #957 of 1560
11/5/07 at 10:59pm
<Homer> 'Doh!!! </Homer>

You're absolutely right...probably shouldn't crank out quick forum replies in the middle of preparing to leave work. In my glee I forget special EE terminology!

I did 'bypass' them in the literal sense by not including them, but it didn't occur to me in my haste that the word 'bypass' has a special EE meaning!
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post #958 of 1560
11/7/07 at 10:51pm
Quote:
Originally Posted by tomb View Post
You have to find the right time of the day. My hands shake, too, but I try to find a time of the day to set aside where I think I'm laid back enough to do some good soldering on the Alien. Most of the time, that's early in the morning on a day I don't have to go to work, but if you tied one on the night before, that might not be a good time, either.
When I sat down to build mine, my hands were a little jittery from a couple of cups of coffee. I found a glass of wine helped heaps (not an alcoholic ). I also ditched the magnifier off my "helping hands" stand because a) it was useless and b) it threw off my hand-eye coordination.

On the soldering front I found that my wimpy electric iron with a very fine tip wasnt pushing enough heat onto some of the joints (namely the ones connected to the ground plane) to get good flow, so for a few I used my butane iron (carefully).
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post #959 of 1560
11/8/07 at 2:52am
Any idea where to get a REG101UA-A or REG102UA-A? TI, Mouser and Digikey are all out. Mouser has an expected date of Aug 2008. Any alternatives? I don't want to make this wall powered if possible.
Thanks
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post #960 of 1560
11/8/07 at 7:03pm
hey finished my second alien a while ago for to post pics of my first one for a friend in a tin so heres my hammond, also my new rca cable!





sorry bout the kack cam phone pics
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