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Alien DAC v1.1 Construction Thread - Page 95

post #1411 of 1560
9/7/08 at 11:25pm
Would dropping the voltage to say 7-9 V be OK ? I don't want to put too much stress on the regulators is all.
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post #1412 of 1560
9/10/08 at 2:07pm
when paralleling a bunch of film caps to use at the output, like tomb and royewest did with their vitamin Qs, is 330k the best resistor size to use?
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post #1413 of 1560
9/10/08 at 5:18pm
Hi,

What happened to the Alien DAC design thread mentioned in the Alien DAC Overview? I have several questions and hate to replow ground that has probably already been covered. The link to the design thread points to the Head-Fi "For Sale" section. I guess the forums were re-indexed at some point.
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post #1414 of 1560
9/10/08 at 5:23pm
I think that thread is here---->
http://www.head-fi.org/forums/f6/pcm...sion-b-137298/
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post #1415 of 1560
9/10/08 at 5:36pm
Quote:
Originally Posted by duncan! View Post
Hi,

What happened to the Alien DAC design thread mentioned in the Alien DAC Overview? I have several questions and hate to replow ground that has probably already been covered. The link to the design thread points to the Head-Fi "For Sale" section. I guess the forums were re-indexed at some point.
Yep - a fairly significant event. Try the search tool - it should get you there eventually.

EDIT: Looks like MisterX got it for you - too many distractions between typing and posting again.

Quote:
Originally Posted by pinkfloyd4ever
when paralleling a bunch of film caps to use at the output, like tomb and royewest did with their vitamin Qs, is 330k the best resistor size to use?
I just used 330K - mostly because I ran all my leads back to the board and that's what was there anyway. I think FallenAngel and Royewest tied their resistors to ground up front with the capacitors. The resistor serves two purposes - to keep the capacitors charged when the circuit is active, and to drain residual charge when it's not. As such, I think the value is somewhat arbitrary - I've seen 50K elsewhere - but unless you have a good reason to use something else, you should probably stick with this value.
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post #1416 of 1560
9/10/08 at 5:42pm
Quote:
Originally Posted by MisterX View Post
Wonderful! I was searching for all things Alien and didn't catch it. Thanks again.
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post #1417 of 1560
9/10/08 at 5:45pm
Quote:
Looks like MisterX got it for you - too many distractions between typing and posting again.
Well I give you an A for effort anyway. Thanks.
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post #1418 of 1560
9/10/08 at 11:44pm
Quote:
Originally Posted by tomb View Post
I just used 330K - mostly because I ran all my leads back to the board and that's what was there anyway. I think FallenAngel and Royewest tied their resistors to ground up front with the capacitors. The resistor serves two purposes - to keep the capacitors charged when the circuit is active, and to drain residual charge when it's not. As such, I think the value is somewhat arbitrary - I've seen 50K elsewhere - but unless you have a good reason to use something else, you should probably stick with this value.
ohhh I thought you guys were using extra off-board resistors for some reason. I'm confused; can I just parallel a bunch of Vitamin Q's and connect one end of them to one output cap pad and the other to the other pad (on the same channel of course); just as if it were 1 cap? If so, I guess I'm just confused about how royewest had it originally that didn't work
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post #1419 of 1560
9/11/08 at 8:59am
Quote:
Originally Posted by pinkfloyd4ever View Post
ohhh I thought you guys were using extra off-board resistors for some reason. I'm confused; can I just parallel a bunch of Vitamin Q's and connect one end of them to one output cap pad and the other to the other pad (on the same channel of course); just as if it were 1 cap? If so, I guess I'm just confused about how royewest had it originally that didn't work
Yes, that's correct.

I think the confusion comes in because of the caps/method used. For instance, I remember seeing FallenAngel's Alien with Auricaps or Mundorf's at one time or another. If you lay the film caps out lengthwise, the far lead is as far away from the board as you can get. In that case, it's easier just to run a ground wire from the board to the end of the output lead of the film cap, then put a regular leaded resistor inbetween. That's what Royewest did also, I believe.

In my case, I wired up the paralleled VitQ's as if they were batteries. So, all the leads ran back to the board.
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post #1420 of 1560
9/14/08 at 3:27pm
Me and a buddy wanted to give the Alien kits from GlassJar Audio a shot yesterday, but have run into problems. (Actually, I left all the soldering to my byddy, because he's less afraid of SMD soldering than me)

When the boards were populated, one measures correctly on both voltage test points (3.3V and 4.7V if I'm not mistaken), but the other has about 1V on both points. (This is on USB power),

Both DACs are detected in windows, but the one with the dodgy voltage readings disappear again after a short while.

We suspected the solder points around IC2, and tried reflowing those - among others.

At one point during the troubleshooting/messing around, there came smoke from - or from underneath - C1. (Uh-oh!)

Does anybody have any good tips for us about what to do next?

We haven't tried to play any sound through any of the DACs yet, btw.
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post #1421 of 1560
9/14/08 at 4:16pm
I think you need to try to take clearer pics - there's not much anyone can tell from those, other than perhaps some cold solder joints. That's a stretch, though. They may look fine when you clear the photos up.

BTW, you need to jumper S1 or neither board will work.
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post #1422 of 1560
9/14/08 at 4:26pm
S1 was jumpered after thatshot was taken. I'll remove the pic until I get a better one of both sides of the faulty one,

Thanks
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post #1423 of 1560
9/15/08 at 4:53am


[/QUOTE]

Its been a few weeks and I've finally been able to get back to this project. There are a few posts a few pages back that refer to this project, though things have changed.

Before, I was getting a weird filtering effect going on. I was measuring voltages across the board, and I think I must have goofed somewhere, because now there is no sound coming out of the left channel. When I measure the voltage at (+) CL, there is a slight blip in the meter, but not the ~2.3 I'm expecting. My guess is the PC2707 chip is fried. Does anyone have any other ideas?

Thanks
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post #1424 of 1560
9/15/08 at 10:43am
This is more of a casing question, but anybody know the best way to cut out the square hole for the USB in the aluminum end of a 1455C801?
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post #1425 of 1560
9/15/08 at 11:40am
Dremel, I guess.
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