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Old 26th August 2013, 01:34 PM   #2491
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Maybe the DAC board is too close to that bunch of "noisy" EI transformers?

I like that way of assembling the rectifier bridge, never seem it before
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Old 26th August 2013, 10:07 PM   #2492
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Quote:
Originally Posted by deadhead View Post
Looks good... hope you trace the problem.

Where did you get the case with the heatsink sides in the last picture from please?
thunk you
Aluminium Chassis
I bought from web in Thailand ,maybe oder to come from China.

Quote:
Originally Posted by troystg View Post
"have problems with hum."

I see a lot of unshielded, barely twisted wire.. That might be a good place to start.

But it does look good..
thunk you
Quote:
Originally Posted by regiregi22 View Post
Maybe the DAC board is too close to that bunch of "noisy" EI transformers?

I like that way of assembling the rectifier bridge, never seem it before
thunk you
Click the image to open in full size.
I use that (cooking foil put on pcb) under PCB DAC
(2 layer frist cooking foil put on pcb/second layer PCB DAC )
wire all= Teflon wire silver plat
I checked.
dac ok
pre have problems (12ax7&12au7)
power amp ok
maybe hum from pre tube (Heater)
I will try. use mc7806
+6 for pin 4/5
0 for pin 9
--------------
Unfortunately with bad language.

Last edited by tigersilver; 26th August 2013 at 10:31 PM.
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Old 26th August 2013, 10:48 PM   #2493
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Click the image to open in full size.
Click the image to open in full size.

Diode i use 25a Because this Series in Thailand is sold only 25a
Vishay HEXFRED® Ultrafast Soft Recovery Diode, 25 A
http://www.vishay.com/docs/94064/hfa25pb6.pdf
Vishay HEXFRED®
Vishay - Diodes - Rectifiers - Ultrafast Recovery Hexfred®

Last edited by tigersilver; 26th August 2013 at 10:55 PM.
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Old 27th August 2013, 03:20 AM   #2494
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Unfortunately with bad language.=sorry, i'm verry bad language
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Old 27th August 2013, 01:22 PM   #2495
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Quote:
Originally Posted by tigersilver View Post
thunk you
Aluminium Chassis
I bought from web in Thailand ,maybe oder to come from China.


thunk you

thunk you
Click the image to open in full size.
I use that (cooking foil put on pcb) under PCB DAC
(2 layer frist cooking foil put on pcb/second layer PCB DAC )
wire all= Teflon wire silver plat
I checked.
dac ok
pre have problems (12ax7&12au7)
power amp ok
maybe hum from pre tube (Heater)
I will try. use mc7806
+6 for pin 4/5
0 for pin 9
--------------
Unfortunately with bad language.
While aliminium may be effective against EMI radiation, the MAGNETIC field from a transformer would only be shielded if using steel or any mu metal. I'm afraid aluminium or even copper should render useless for that purpose. Anyway, you still have the top aluminium cover acting as an EMI shield, so there should be no point in using that extra layer
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Old 28th August 2013, 03:04 PM   #2496
Mihkus is offline Mihkus  Estonia
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The cooling is total overkill for 100W amp...
Chips in use are LM3875 at +-30V Cap bank almost 1F...


Click the image to open in full size.
capture screen

Last edited by Mihkus; 28th August 2013 at 03:07 PM.
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Old 28th August 2013, 03:09 PM   #2497
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Quote:
Originally Posted by Mihkus View Post
The cooling is total overkill for 100W amp...
Not neccesarily, it's allways a good idea to maintain the lowest possible die temp to keep the spike protection happy
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Old 31st August 2013, 07:21 PM   #2498
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Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.



2 laptop smpsu for +-19v 2x lm3886 on amd cpu heatsink with small fan , i think it is around 20w*2 and it gets barely warm on normal listening
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Old 2nd September 2013, 03:03 AM   #2499
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Here's my first electronics project, pretty much buttoned up. It's a pair of LM1875 chips built with BrianGT's kit and the standard Avel transformer. The enclosure is sort of a cobbled-together prototypical thing since I wanted it done in time for a party this weekend; I was inspired by Make magazine to build a powered speaker to use in the fabrication shop where I work, and I was going to base it on the Monobox but the more I looked at the Monobox the more I felt it was underpowered. I started looking around for alternatives and decided a Gainclone was just the ticket. Then I started to realize that the Gainclone is way overkill for a shop stereo (what with all the machine noise and forklifts and stuff), so it's probably gonna live at home with me since it's nicer than my current receiver while I figure out an even cheaper shop solution.


IMG_4769.jpg
Here's the thing assembled. Down the line it's gonna get a custom aluminum enclosure, since it runs pretty hot and takes up more space than it needs to.




IMG_4774.jpg
And here's the guts. It being my first project, a lot of it is pretty amateurish (the back panel isn't drilled at the right height for the LM's through-holes, meaning that the PCB base sits at a slight angle). There's a lot of solder and electrical tape where there should instead be crimped terminals and heatshrink, the LED is just floating in there, I accidentally only bought one set of speaker terminals so there's a pair of output wires temporarily sticking out the top, etc, but it works!

An idea is to build it into a water-(and beer-)resistant Al case and do the same with a pair of speakers that'll latch on for transportation, but it took about 30 hours to build this thing so it's time for a lil break from DIY projects (not a very long break, though. this was really satisfying).

I've learned a ton and gotten a lot of really good ideas from reading threads here, so thanks for that! I'll try to return the favor by posting more pics when the enclosure gets rebuilt.
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Old 2nd September 2013, 03:29 AM   #2500
Pano is offline Pano  United States
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Please remember to resize your photos before posting. No need for 1 MB images on the web. Thanks.

Pictures -- Why Not attach Them ??
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