[Corbet]

I'm a new DIY'er when it comes to headphones, but I think I have a fairly decent grasp on the concept.

Instead of building a CMOY, which I'm sure everyone will recommend, I'm looking to tackle something of use to me - the Alien DAC for my Macbook Pro.

I realize there is a Alien DAC thread but 50+ pages is alot to shift through, so I thought I'd ask ask a few questions here.

Where can I see people showcasing their Alien DACs?
What kind of enclosures should I consider? I know people recommended Hammonds, any other options?
I'm looking to get the kit from Glass Jar Audio, listed here: http://www.glassjaraudio.com/category.sc?categoryId=4

Will I need anything else with that kit besides a enclosure?
Is there any advantage/disadvantage from having the DAC powered via USB?
Anyone have an extra Hammond case lying around?

 

[eddiewalker]

Hah, you could have asked me after I mentioned the project! To complete Jeff's kit I only had to throw in two RCA jacks and the popular Hammond 1455C, which was like $13 from mouser. I like the case, and the end result looks simple and professional. USB goes in one end, a pair of RCA cables go out the other.

If you're completely new to soldering, however, perhaps SMD isnt the best start, but if you're familiar with soldering in general and just new to SMD, then the Alien DAC is a cheap enough first-foray.

 

[Corbet]

Quote:

Originally Posted by eddiewalker /img/forum/go_quote.gif Hah, you could have asked me after I mentioned the project! To complete Jeff's kit I only had to throw in two RCA jacks and the popular Hammond 1455C, which was like $13 from mouser. I like the case, and the end result looks simple and professional. USB goes in one end, a pair of RCA cables go out the other. If you're completely new to soldering, however, perhaps SMD isnt the best start, but if you're familiar with soldering in general and just new to SMD, then the Alien DAC is a cheap enough first-foray.

Mind giving me those mouser parts #s for the Hammond and RCA jacks?

 

[bhjazz]

Jeff's kit would be the easiest way to conquer the Alien dac. Outside of that, it could be a nightmare! You will need to solder surface mount caps (SMD) which are really small. It will take some practice!

I also encourage you to read that Alien DAC thread. I know it's long, but you'll definitely learn about the options in the BOM and what they will give you. All of your questions (well, except the one about the spare Hammond!) are answered in that thread. At the very least, you can search the thread and look for USB. For the most part, most people use USB power, but running a separate power supply can give some benefits as well.

 

[bhjazz]

Quote:

Originally Posted by Corbet /img/forum/go_quote.gif Mind giving me those mouser parts #s for the Hammond and RCA jacks?

The 1455C is the Hammond 1455C1201. It is here. You can use any RCA jacks for a Hammond case. The end panels are usually .059" thick. For instance, a Cardas GRFA with thick nut would work (try hndmade.com or partsconnexion.com). Also, the Kobiconn jack is a good price. Head out to mouser.com and search for "RCA jacks female" then adjust for the price you want.

 

[Corbet]

So guys... where can I see pics of yours?

 

[Televator]

I will have pics up pretty soon (once I finish casing mine) but in the large Alien DAC thread you don't want to tackle, there are a bunch of pics already...

I will be using a mints case (though I'm still wondering whether I need to isolate the in/outputs from the metal case) as did Tomb.

But unless you have soldering experience on other small things, I would not recommend starting with the Alien DAC (especially if you intend to solder the SSOP28-chip by yourself). It is very precise and sometimes frustrating work and you will easily ruin the (not so cheap) chip.

I already built two Cmoys and a bunch of cables and still I had some close calls (on the miniature capacitors mainly, the chip went ok... but perhaps I was just lucky?)

The glassjar kits need an additional case, outputs (RCA or stereo jack), LED (and LED-holder), (4x 3mm diam) mounting screws (the board is populated at the underside as well, so you'll need something to raise it), and of course the IC's (USB printer-cable) and something for the output as well

 

[tomb]

I didn't isolate anything anything on mine - board ground and signal ground are the same thing on the Alien DAC.

That means the USB connector body and the output jack ground may touch (should touch) the Mint Tin, making things a lot easier.

Quote:

Originally Posted by Corbet /img/forum/go_quote.gif So guys... where can I see pics of yours?

Here's mine - I'd put the pic in directly, but I've already posted them in two places, so that wouldn't be cool to do it again:
http://www.head-fi.org/forums/showpo...&postcount=770

 

[andrew jc]

Just FYI, Jeff sells the Hammond case as well. Is their any advantage of RCA vs single mini output jacks?

 

[eddiewalker]

Quote:

Originally Posted by andrew jc /img/forum/go_quote.gif Just FYI, Jeff sells the Hammond case as well. Is their any advantage of RCA vs single mini output jacks?

It depends what connection your amp takes as an input, really. The signal is the same either way.

 

[Calroth]

If you buy the Alien DAC kit from Glass Jar Audio, be sure to ask them to pre-solder the tiny PCM2702 chip for you. I'm not sure if you have to pay extra, but if you need to, then pay it. Don't argue

 

[Televator]

Quote:

Originally Posted by Calroth /img/forum/go_quote.gif If you buy the Alien DAC kit from Glass Jar Audio, be sure to ask them to pre-solder the tiny PCM2702 chip for you. I'm not sure if you have to pay extra, but if you need to, then pay it. Don't argue

you do have to pay a little bit extra... I ordered two kits, one with and one without presoldered PCM-chip... once they arrived I thought I should try to solder the chip by myself first, and it worked. But I can easily see how this could be a frustrating and expensive thing if it is (one of) your first DIY-project(s) as it is literally the first thing you have to solder onto the board and it is a very difficult part as well!

So yeah, if you really think of going ahead and do an Alien DAC as a first DIY-project (which I honestly don't think is a good idea) get the presoldered PCM2702 chip... and perhaps ask if Jeff can solder the rest of the (tiny) SMD-parts onto the board as well

BTW: thanks Tomb... I reckoned that as well... just that I seem to have a bit of a problem coupling my Alien DAC to my Powerbook G4 and Cmoy. It works fine for half an hour to an hour, then it 'shorts'(?) with a loud high-pitched whine in my headphones...I was wondering whether it happened because both use grounding to their tin case (eventhough the cases weren't touching) but I guess I better post this problem in the Alien DAC-thread

 

[tomb]

Quote:

Originally Posted by Televator /img/forum/go_quote.gif <snip> BTW: thanks Tomb... I reckoned that as well... just that I seem to have a bit of a problem coupling my Alien DAC to my Powerbook G4 and Cmoy. It works fine for half an hour to an hour, then it 'shorts'(?) with a loud high-pitched whine in my headphones...I was wondering whether it happened because both use grounding to their tin case (eventhough the cases weren't touching) but I guess I better post this problem in the Alien DAC-thread

Yes, you should probably post this in the Alien thread. I haven't had this happen with mine, yet have connected to multiple PC's and amps - not Apples, though. Actually, what you describe sounds heat-related. One of the regulator chips may be bad or perhaps you have a close-to-bridged joint. When it heats up slightly from normal operation, it eventually expands enough to short out - or the chip is marginal and it stops working when it gets warm. Just a guess ...

 

[Corbet]

I'm actually having my friend, who is a electrician and is supposedly really good with a soldering iron help me.

 

[holland]

It's actually pretty easy for a first-time DIY. I soldered the PCM myself, it was cake.

What I learned.

1) Spring mounted tweezers + SMD parts do not mix.
2) A flat hard surface around your work area is nice.

I spent 2 days looking for some caps that shot off my tweezers and were "lost" in carpeting. That was the only time I was grateful that DMMs can measure capacitance, once I found the parts though.

Do yourself a favor and get some loupes or something with heavy magnification to check the joints of the SMD parts.

Also get a very fine tip for your soldering iron. You'll need it for some of the larger SMD items, like the caps.