Replace LM1117 with 78XX regulator

[gwillys]

a aune/hifidiy mini usb dac  is coming. i would like to replace the 3.3 & 5v LM1117 regulators with externally powered 78xx super regulators, but the connection is different.
 
i can handle the soldering, the electronic side is a total loss for me. on the LM1117, input-output-gnd i can follow, but the Vout has thrown me
 
if it's possible, can someone advise me how to configure the wiring. keeping in mind i'm a rookie.
 

 

 

[cfcubed]

Asking for this to be moved to the DIY forums might help:  http://www.head-fi.org/forum/list/6

 

[MrSlim]

The output and Vout pins are common.  The Vout tab is the device heatsink.  It is identified as Vout to make sure you make the appropriate choices about keeping it isolated. 
 
If you want assistance with the wiring, you'll have to provide more details on the "super regulators".

 

[gwillys]

thanks MrSlim - makes perfect sense. i've replaced smt 78xx regulators before, so i can handle the rest i think, using the pinout diagrams.
thanks again.
 
and thanks for the headsup, cfcubed.

 

[francisdemarte]

What are the benefits of doing this?

 

[gwillys]

Quote:

What are the benefits of doing this?

look here: http://www.newclassd.com/index.php?page=70
i'll use them for the digital side,
& this for analog: http://bursonaudio.com/burson_super_regulator.htm
 
i'm also going to change out the clock, caps, & whatever else i can figure out.
for fun
 

 

[francisdemarte]

Interesting.
 
Why not just build a nice external DC power supply and filter the power going into the unit to begin with than to try to do that on the board level?
 
I also noticed you have the Burson discrete opamps. How do you like them?

 

[gwillys]

to get the LM1117's out of the loop, and have the reg where it's designed to go. trust me, it makes a difference. you don't see higher-end units using LM1117. maybe mostly, they are cheap & small & low dropout.
 
the bursons are fine. once you go discrete, you dont go back. at least thats the way it seems. 18v between pins 4 & 8 is ideal for best performance. i'll use a burson reg there, because it's adjustable 10/20v, with probably around 25v input for 18v out.
i have a 0-30v bench psu, so i can play around with voltage
 
dont really know what i'm doing, but i've figured a few things out.
 
a proper power supply would be great in addition to the regulators, but i have no idea what to, or how to build a psu. i'd probably kill myself. kind of scatterbrained in my old age.
 
+, i already have most of this stuff, after destroying a asus st, so why not...

 

[francisdemarte]

Once your done with those mods post up your impressions in the main Aune thread here:
 
http://www.head-fi.org/forum/thread/407756/hifidiy-s-mini-usb-dac-mk2-also-a-headphone-amp
 
A decent beginner's power supply DIY kit can be purchased here:
 
http://www.tangentsoft.com/elec/tread/
 
Takes about 15 minutes to put together if you have a little soldering experience. 
 
I believe the Aune can take up to 24V DC in but I've found no improvement with anything over 18v DC.
 

 

[gwillys]

yes, thanks, i've seen that thread. the tangent reg is nice, but over my head, which doesn't take much.
i may try powering the aune @ 12v, but ext. psu for 78xx and another for 18v to opa.
 
i'm thinking i'd like to do away with the LM1875, but i'm not sure what thats all about. a power amp used as a regulator/psu?
i'm mainly interested in rca out.
 
do you see any logic to my madness?
 
it wont be here for a few days at least, maybe it will make some sense when i see it.
-------------------------------------------------------------------------------------------------------------------------
just went thru the old wallwart box. i'm in good shape, allowing 3v or so for dropout with the super duper regulators.

 

[gwillys]

aune/hifidiy mini dac arrived today. out of the box, after a few hours burn-in, it blows the stock asus st away.
 
new caps to order, and then mod's begin.
 
i'm going to rig a heatsink for the LM1875  so i can operate the board outside the case, to check voltage etc..

 

[francisdemarte]

I believe the LM1875 is the virtual ground splitter. You can do away with it if you use a dual power supply.

 

[gwillys]

thanks. virtually greek to me, but i'll sort it out

 

[gwillys]

 francisdemarte - you gotta try a burson opa in the  opa2604 position. amazing. a transformation.
i had tried a couple others, but no comparison.
90 bucks at partsconnexion and puts this dac in a different league.
 
so far, the opa2134 seems better left alone.
 
with the result from the burson opa, i can see this little dac is worthy of upgrading
 
anyone interested - contact Jack @ burson & tell him 'gene' sent you. i bet he'll make you a better price.
he sold me 3 for 160usd incl. shipping to usa. probably not as steep a discount for 1, but ask anyway.
 
due to the vol pot, there may be fitment issues. i'm using a opa lead extension. you can ask Jack about that.
 
case is removed, front & back plates in place.
LM1875 is heat sinked.
i'll probably order caps today & measure voltage.
 
the supplied '15v' psu puts out 24v no load, and i'm getting 21v at opa pins 4 & 8.

 

[francisdemarte]

I've been wanting to try the burson opamps for some time now but was hesitant due to the price and lack of reviews. I think you've convinced me to order a couple.

I'd suggest we move this discussion to the main thread I linked earlier. You'l have more people reading and commenting.

I always considered this amp to be way under rated, maybe your project can drum up more interest!