DAC 2496 (AK4393) DAC KIT With CS8416+AK4393+5532 - Page 178 - diyAudio
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Old 13th May 2012, 07:36 PM   #1771
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hi, i'm about to start this project starting with smd soldered pcb order from fleabay.

it's nice to see couple familiar faces from myref threads. the quest for the ultimate sound must be a narrow road

quick question tho- I plan on battery powering this thing through the regulator holes- would it shorten the battery life considerably if i were to go passive trafo output?

Last edited by PreSapian; 13th May 2012 at 07:48 PM.
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Old 13th May 2012, 08:28 PM   #1772
xslavic is offline xslavic  Moldova
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Yes you can,check schematics for car use
and connect the others directly
...just remeber to play with those LM 7819 ,lm7812 + lm7912
first does'NT need a center tap and second does
But the Lm317 ,117 can accept higher voltages than 9 and 12 so heck them out
remeber that there is +gnd and +gnd- ,sometimes they get along toghether
like +gnd from the +gnd-
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Old 14th May 2012, 03:44 AM   #1773
TheGimp is offline TheGimp  United States
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The main issue with that design is that it is pretty inefficient. The design is simple and works well, but the current with no load is rather high.

For example, I built one with a Triad F-140-XP (12.6V at .178 rating)and the current with no load was 360mA. Output was 96Vac with 12.6VDC in.

Note that the output voltage is below the expected 120VAC, because you will need over 18Vdc to get 115Vac out of the transformer as the DC supply has to exceed (for losses) the peak value of the expected RMS output voltage.

Transistors need heat sinks.

Last edited by TheGimp; 14th May 2012 at 03:54 AM. Reason: add heatsink note.
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Old 14th May 2012, 08:14 AM   #1774
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it seems that (from skimming through the thread for the past two days) many who went passive output from the dac chip report some sort of high freq harshness. doesn't the 4396 not need a lpf because the distortion is moved up into subsonic range, or does this still affect the audible freq? if so, passive mod+lpf= not possible? i was in the understanding that the transformer output would naturally roll off the highs

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Old 14th May 2012, 01:26 PM   #1775
TheGimp is offline TheGimp  United States
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In order to meet the manufacturers specification for s/n and distortion, it is necessary to utilize an LPF on the output. If I read the data sheet correctly, the difference is nearly -20dB.

I also saw a considerable upswing in floor noise from 20KHz up to 48KHz on the FFT, which after reading the referenced article looks like it is from the DAC noise shaper. It may be possible to change this if the DAC were changed from HW mode to SW mode by controlling it withe a PIC or Arduino.
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Old 14th May 2012, 02:18 PM   #1776
bcmbob is offline bcmbob  United States
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PreSapian, Just out of curiosity, are you planning to use this DAC in a mobile/car application or are there other reasons you want to use a battery?
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Old 14th May 2012, 02:40 PM   #1777
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hi bob, im planning it to use it in conjunction with myref and a ribbon tweeter 3 way as my main setup. considering the associating components now im thinking i may hav to go for active buffer with lpf, because that 40khz rise will be present in the final output.

i'm wanting to use battery because it should sound better

Last edited by PreSapian; 14th May 2012 at 02:43 PM.
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Old 14th May 2012, 03:12 PM   #1778
bcmbob is offline bcmbob  United States
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Got It - I've just seen so many varying approaches to powering and modifying the power for this unit that I am trying to determine which way to go if I decide to make further modifications. The upgrade BOM was a big improvement and any further refinements would truly be beyond my expectations. There have been several posts dealing with battery power but not a lot of follow-up. Maybe those builders can also add some information here.

Please let us know how the Ever-Ready Bunny performs his tasks.
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Old 14th May 2012, 03:42 PM   #1779
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ͧ*响
these discrete modules might be worth looking into. its what ill go for if theres no positive assurance for output trafos
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Old 14th May 2012, 07:13 PM   #1780
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What about 5 small batteries? One for the 9 V stage, and 2 x 2 per each 15V part (you can try 12V only then you need 2 batteries, but I am not sure it will work well with the op-amp).

So take two batteries, put them in series, and supply this to the + 15V part. Do the same for the -15 V part.

Make a switch, that when you turn off the power (main switch), the switch automatically switches on a charger and disconnects the DAC board (so some relays are needed). That way the battery is always charged when you need it.
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