Alien DAC v1.1 Construction Thread - Page 101

OK - I missed the part about the RCA Jacks. It was late and after the Super Bowl when I had that thought - sorry.

If your wiring is OK, then I can't explain the rest of it. Even if your amp had a super-low input impedance, 47uf should be gracious plenty to cover any cutoff frequency issues.

Hi guys,

I just finished building my alien dac, but sadly, my macbook pro isn't recognizing it, and I don't know where to start the trouble shoot. I've noticed no solder bridges, cold joints, etc. The chip was soldered by Jeff, and mine looks exactly the same as the pictures from other glass jar alien dac owners.

Here are so pictures, in the mean while I will continue to browse in this thread. Thanks.

Unfortunately, I see a few cold joints.

Before you start worrying over that, however, plug the USB in again. Measure what you get at the 3V3 point and Gnd. Then measure what you get at the Gnd and 5V point. That should tell you if the regulators are working. Most likely, if the PCM chip is OK but your computer can't recognize it, there may be a problem with the 3V3 regulator.

Thanks Tomb for the response! I tested both points, and got 3.3v at 3v3, and 4.7v at 5v. So I guess something is working. I tried plugging it into my brother's vaio(windows), it picks it up but the device is not recognized.

I will reflow the joints again. In the mean time, what else should I check?

And also, do i need to discharge the caps to protect the chips like I need to on the mini3?

Thank you so much TomB, I really hope my $50 isn't going down the drain!

Woohoo!! Just reflowed some joints, plugged it into this old pos windows tablet(forgot how slow windows boots up...), and it read burr brown japan! I then verified it on my bro's vaio as well! I then plugged it into my macbook pro, went into the audio set up, and viola! It is there!!
Thanks TomB for making fun of my cold solder joints! You brightened my day!

Thanks for having such a good attitude and not giving up! Glad you got it working!!

Yeah I feel that a lot of joints on my BantamDAC weren't soldered on properly/cold joints (applied solder to tip). I was thinking of doing a large soldering wick/resoldering adventure when I get a new iron. Do SMD components get damaged by heat easier due to their size/nature?

In my experience with this alien dac and the mini3(smd op amps), they can take quite a beating. I pretty much raped two smd parts(flux everywhere, melt/scratch marks on the resistor from tweezers and iron) when I thought there were solder bridges. I was convinced my dac wouldn't work, but what do you know, the computer recognized it. I plan on redoing those parts as soon as I can get a hold of those components. As for cleaning the board, I've been having trouble finding pure alcohol, can I use contact cleaner(3in1 brand)?

You can get 99.9% isopropyl alcohol from Fry's if you have one near you. Otherwise just look online i'd say.

I have a Fry's in Dallas, but I am in Hong Kong right now.. hehe. I did look on Farnell(wow they have great service, overnighted shipping from Singapore for free, and their packaging is meticulous), but none to be found. I will keep looking in chemical stores here in HK.

What caps are you guys using for cl and cr? I want to try and put something else in it, do I have to stay within a certain voltage and uF range? Yes I am a newbie!

Thanks

You can get 91% alcohol at Walmart. It works fine - it's all I ever use. As for contact cleaner, I'm not so sure. It's probably not nearly the solvent that alcohol is. Plus, many of those concoctions actually work by using a spreading type of viscous fluid that's electrically conductive - probably not something you'd want to put on your board to clean it.

As for output caps, the SOP for the Alien DAC is the Black Gate NX Hi-Q, 47uf 6.3V. However, Handmade Electronics sell some nice substitutes that may work just as well - an Elna Cerafine at 47uf 10V, sometimes referred to as just as good as a Black Gate, but without the break-in period, - or an Elna Silmic II RFS at 47uf 6.3V, a favorite of many Alien builders. Both are very cheap, as is the Black Gate at that size, really (Soniccraft.com or Parts Connexion).

The ES caps that come with Jeff's kits are very serviceable, but really benefit best from bypassing with a good film cap. That's a bit difficult in the Alien and I wouldn't recommend it starting out - better to just try the different ones I mentioned if you're itching for some improvement.

Hello tomB,

I was able to locate some 99.5% iso alcohol here in Hong Kong, in a gallon jug though, hehe. For aournd $19USD, not a bad deal. Is it safe for plastic? I was thinking about perhaps cleaning some other stuff with it since I have so much.

I will give those caps a try, there are a lot of old school audio stores here in HK that carry the Black Gates, I will give those a try. WOuld changing the other caps to Black Gates as well benefit the sound signature? Or are cl and cr the only ones that matter?

Thanks for your help brother.

CL and CR mostly. You can upgrade the other caps with larger, better quality power caps, but results are not nearly as significant as with upgrading the boutique caps at CL and CR.

There's no point in using boutique, audio-quality caps in the power positions - they won't even be as good. You can easily go as high as 330uf for the regulator caps and 1500 for the large power cap. We use 1000uf and 1500uf for the BantamDAC with great success.

Probably the biggest difference in the Alien is to go with nice film caps at CL and CR, but this requires some out-of-the-box planning and construction. There's no way you can get film caps on the CL/CR pads on the Alien without wiring off-board leads and perhaps the resistors, etc. Depending on the input impedance of the amp you're connecting to, you may have to get film caps that are very large physically and very expensive. Also, be very careful if you try something like this, because those caps are the only thing protecting the outputs of the PCM chip from getting fried. You should make sure you have secure connections before connecting it to anything if you try it.

You will have very noticeable improvements by trying some of the electrolytic caps I mentioned earlier, however.


P.S. The isopropyl alcohol you mention should be plenty safe for the board and parts. In fact, you can use it for immersion when building - prior to installing the electrolytic caps. Electrolytics are solvent-resistant, not solvent-proof. So rinsing a finished board with a toothbrush, etc., is fine, but I wouldn't immerse the whole thing once you have electrolytics on board.

Thanks for the post Tom, very very informative, I appreciate it!

I already cleaned the board, I'm sure alcohol was on the electro caps, but the dac works fine. Definitely make a note on that in the future!

Unfortunately, the shops here in HK that carry Blackgates do not carry the 47uf 6.3v... nor do any of them carry the elna silmic IIs... I googled the parts but came up empty, checked on beezars as well. Would you happen to know where to purchase these boutique parts?

*edit* I found this site that sells elna silmics, however they only have the silmic in 47uf, 35V, that won't work will it?

*another edit* this site sells the cerafine and silmic II, but they don't ship overseas.. http://www.hndme.com/productcart/pc/...?idCategory=13

I saw the pictures of the vitaminq film caps in the earlier posts, definitely a beautiful thing! I do not plan on doing films caps anytime soon, since I have no clue to what i'm doing(let alone finding the parts in HK)!

Thanks tom.

Note that it doesn't hurt to get alcohol on electrolytics - it's immersion that may be the problem.

As for the vendors on those caps - I listed them in the original post where I described those caps. As you found, Handmade Electronics is the source for Elna Cerafines and Elna Silmic II RFS, although Silmics can be had at DigiKey, but not in the size we're talking about. The Black Gates (repeating this) are at Soniccraft.com or Parts Connexion, a Head-Fi sponsor. Parts Connexion is in Canada anyway, so I doubt they will have any issue with international shipping. Soniccraft is in Arkansas, so I don't know about their international policy, but they are so good it's worth a check/call.