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Alien DAC v1.1 Construction Thread - Page 70

post #1036 of 1560
2/6/08 at 3:31am
Stability while flapping around outside, maybe (thanks). In a mint tin once everything is secured in place, stability is over-rated, and it looks cool anyway!. Short leads take over I'm thinking of re-positioning the caps to be more parallel to the end of the board and much closer, if they'd fit, but they probably wont, and since it all works, I've got more stuff I'm likely to 'break' first What vit Qs would you try? you'd need 3 0.22s to get a cut-off freq of 4~5Hz into a 50K load..
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post #1037 of 1560
2/6/08 at 3:45am
Quote:
Originally Posted by ruZZ.il View Post
<snip>What vit Qs would you try? you'd need 3 0.22s to get a cut-off freq of 4~5Hz into a 50K load..
I was thinking 0.22uf's to bypass with BG's, but 0.47uf's when by themselves. I've got four more going right now that I'm going to experiment with - also will try to fit them in under the board in some MAXes, if that's possible. Laying all the caps down will make it pretty flat, but by the time you count the clearance needed from the bottom of the case plus the solder blobs/leads under the board, it's less than 3/8" of inch working space. There may be a way I can mount one on the inside of the backplate - I'm not sure, yet. The L-Com panel-mounted USB jacks will help, but they're huge, too.

We'll see ... they may end up in some more mint tins.
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post #1038 of 1560
2/6/08 at 4:18pm
meanwhile, I got another A.dac running and am using some silmic IIs that jeff supplies to make sure its running nicely while I wait for some BGs. I must say, the silmic IIs are pretty decent all-rounders. A little less bass than the ES-GENII combo and a little less detail from my familiarity with BGs. Slightly less 'smooth' than both, but a fairly balanced sound.. not bad at all..
going to compare it to my burnt in silmic II A.DAC that I haven't used for a while..
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post #1039 of 1560
2/20/08 at 7:53pm

Up-ing the brightness of the LED

Hi All,
I recently finished my first Alien DAC which turned out great (check the build picts thread for shots) but I'm not happy with the brightness of the LED. It's dimmer than I'd like. Is it safe to lower the resistance of RLED?

Thanks!
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post #1040 of 1560
2/20/08 at 8:02pm
Quote:
Originally Posted by willco007 View Post
Hi All,
I recently finished my first Alien DAC which turned out great (check the build picts thread for shots) but I'm not happy with the brightness of the LED. It's dimmer than I'd like. Is it safe to lower the resistance of RLED?

Thanks!
Yes. If you look at the schematic, the LED/RLED are connected between 3V3 and ground. RLED will drop ~1.5V with a standard red LED (1.8V), and the default 600R value will pass only 2.5mA. Most standard LEDs are rated for about 20mA, so you could decrease it to 75R.
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post #1041 of 1560
2/20/08 at 8:10pm
which LED do you have?.. I guess RLED could be lowered a bit, but not by too much..

check the LED spec sheet for what voltage to try obtain and at what current it it should be at, then:
R=(Vs-Vled)/I
Vs=3.3 on the Alien..
Most diodes use about 2~2.5v, so the LEDs are only drawing 2~3mA with RLED at 600R. half that would be 5mA which the reg. should still be able to handle..
I find that with my ultra-bright LEDs I get them even too bright with RLED=600R, so you're probably better of getting the right LED and keeping the current down.

edit: I was beat to it and he also knows what he's talking about, so I guess the reg can easily handle a bunch more mA quiet happily.
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post #1042 of 1560
2/21/08 at 1:58am
Thanks for the prompt replies. I'll check it out.
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post #1043 of 1560
2/23/08 at 5:18pm
I just discovered something that other amp builders may run into in the future if they integrate an Alien and an ε12 protection circuit into the amp.

I omitted the CL/CR coupling caps on the Alien because the amp it was hooked up to used a DC servo to nullify DC. I figured one less part in the signal path = one less opportunity for signal degradation. However, I discovered that it caused the ε12 to disengage whenever I would switch between inputs or change the volume when the Alien was selected.

Adding the coupling capacitors to the Alien not only fixed this problem, but also got rid of some noise I was hearing from the USB.

Hopefully this will save some future builder the same afternoon of discovery that I just enjoyed.
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post #1044 of 1560
2/25/08 at 3:06pm
I've taken in a half built alien to fix up for someone. Most of the caps and resistors were soldered on, somehow, along with the reg's. the PCMx was soldered on by Jeff, I assume, very neatly. I measured the resistors which checked out. I didn't measure any of the capacitors though I proceeded to clean things up, straighten things out and make sure everything was soldered in neatly. I built up the board with the remaining parts substituting the 1M resistor across the crystal with a through hole one I had lying around (was originaly nowhere to be found). C1 was missing but I've ommited it...
Anyway, I fired it up and measured the voltage, which is fine. plugged it in and had snow. When the power is cycled it actually plays for a few seconds before snow blends in and takes over in a sort of intermittent way. I'm assuming its some oscillation/capacitor thing, which I'll continue to investigate. I'm not quiet sure what to measure with the caps while they're on the board but I'll probably replace a bunch of them anyway.
I'm not sure C1 introduces such an oscillation (if thats what causes the snow) since its an 'optional' part, but I'll certainly fill that in too. I'm leaning towards something out of C11-19 being the issue but I'd appreciate any ideas and input anyone could have on the potential causes of the issue.

Much appreciated

-Russ.
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post #1045 of 1560
2/25/08 at 8:24pm
Quote:
Originally Posted by ruZZ.il View Post
I built up the board with the remaining parts substituting the 1M resistor across the crystal with a through hole one I had lying around
....
I'm assuming its some oscillation/capacitor thing, which I'll continue to investigate.
Oscillation and non-regular part by the oscillator... I'd try to get a proper 1M resistor first
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post #1046 of 1560
2/25/08 at 9:53pm
didnt feel like wasting too much time, I changed out c14, c19, X1, R14 and added C1, works like a charm
the downside of the batch work, I'm not sure what the culprit is. I'll try substitute some of the parts I've used with alternatives to keep a concise spare set and check out the ones I've taken out again. at least its alive..
Thanks for the response though! it's comforting to know its not just me behind the wheel =)
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post #1047 of 1560
3/1/08 at 3:45am
Quote:
Originally Posted by tomb View Post
I decided to finally bypass my Muse ES Alien - particularly since it had become almost unused.

I proceeded to add the 0.22uf Sonicap GEN II's - as recommended for so long by Dsavitsk.
Hi tomb,

Hey, just wondering which ESs you were using? Is it the 33uF or the 47uF? I'm going to be shoring up the last parts I need over the next week and wanted to try the bypass route.

Also - (and just to be sure): when you say bypass, you mean connect the Sonicaps in parallel to the ESs, correct?

Thanks!
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post #1048 of 1560
3/1/08 at 4:07am
Quote:
Originally Posted by bhjazz View Post
Hi tomb,

Hey, just wondering which ESs you were using? Is it the 33uF or the 47uF? I'm going to be shoring up the last parts I need over the next week and wanted to try the bypass route.

Also - (and just to be sure): when you say bypass, you mean connect the Sonicaps in parallel to the ESs, correct?

Thanks!
Bypassing is using the Sonicaps in parallel, should sound good

You can use either, and definitely smaller valued ES caps, anything over 4.7uF is effectively usable for any amp.
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post #1049 of 1560
3/1/08 at 6:34am
Actually, the ES's are 33uf 16V. The 47uf's at Handmade are 8mm in diameter and won't readily fit the board. 'Course, whether a cap fits the board or not doesn't stop many of us , but I was trying to follow all the prescribed recommendations when I ordered my parts long ago. FallenAngel's response is correct, though - anything in that range would apply, and as he says, the Sonicaps are in parallel.
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post #1050 of 1560
3/1/08 at 10:33am
I have a FallenAngel built alien dac, and I was running it with my max for around 7 days non stop and took a listen to it one day and heard distortion in the right channel.

I have pinned the problem to the DAC.

But can anyone tell me on HERE where any possible problems might be causing the right channel distortion.

I was thinking the caps but was unable to test that theory yet and if I need to buy new parts I want to buy parts for all the possible problems.
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