Replace LM1117 with 78XX regulator

[gwillys]

that thread is too general - opa rolling. i'll keep it here. most people wont be considering the mods i'm doing anyway.
i'll try to get some pics up soon so you can follow what i'm doing. have to clean my desk first
 
just ordered MUNDORF 4700uf 40VDC MLytic  & 25v elna silmic II's for recap and another burson regulator, but slow delivery from canada.
 
you wont believe what the burson opa does. this one has several hundred hrs burn-in - just amazing.
btw, as i mentioned, so far the opa2134 seems better left alone . havent tried a burson there yet, but
each time i substituted a opa there, sound deteriorated. i'll try a burson later today & report back.

 

[francisdemarte]

Sounds like your going to turn a $150 dac/amp into a $500 one
 
What sources are you using and how are they going to be connected to the Aune?

 

[gwillys]

$1k
 
just a computer, rca out to amp. don't use hp. waiting on a spdif cable. besides cleaning the desk, i had to solder a coax/optical bracket cable to the motherboard because it had the wrong connector. will it never end?
files are mostly lossless, flac/wav & 24-96 when i can get them.
 
btw, i swapped a burson for the opa2134 . same result as others - not good. i'll be running the opa2134 there.
 
if you get one, you'll need an extension, maybe 50mm. it will fit inside the case.

 

[francisdemarte]

The Aune's amp section is a copy of the Graham Slee Solo which was a $900 amp. 
 
So it's computer Coax > Aune > Headphones or you using it as a pre-amp?
 
 The Aune is currently my office amp, my main headphone amp is the Lovely Cube (see link in my sig could be another fun project for you) 
 
Looking forward your pictures and impressions!

 

[gwillys]

no headphones - rca out to amp.
put a burson in your mini, and you'll have a lovely cuboid

 

[francisdemarte]

Hmm...I thought the OPA2604 only affected the headphone amp and the OPA2134 affects both the Dac and the Headphone amp.
 
What if you run the amp without a opamp in the opa2604 position, Do you still get output from the RCA outs?

 

[gwillys]

both work for line out. thats all i know. opa2134 serves as a filter, or so i've heard. maybe a circuit designed just for it's purpose.
very unusual effect when something else is put there.

 

[gwillys]

francis - do you have the instructions on how to wire it for dual psu?
 
look here: http://forum.lowyat.net/topic/1085713

 

[francisdemarte]

No unfortunately the only information about that power supply I've seen were pictures.
 
You can try contacting Coolfungadget or Auneaudio on ebay about it.
 

 

[gwillys]

emailed cfg yesterday. i'd really like to do away with the LM1875. i have the data sheet, but can't figure how it works here.
 
hooked up to bench psu, 18v /.53A. interesting adjusting voltage on the fly. i agree with your 18v determination. 18v is ideal for burson opa and upper limit for opa2134. plus it sounds good. the "15v" psu supplied is too hot - outputs 24v, and i was getting 22v at the opa's.
 
maybe i'll get a different result rolling opa's @ 18v.
 
measured across some caps and they are well under 16v, so no worry there.

 

[francisdemarte]

 
All I can find is this thread: http://bbs.hifidiy.net/viewthread.php?tid=128858
 
May give a hint on the parts that need to be removed. The pictures seems to be of an older version of the Aune board.
 
The dual PSU, I think, but I'm not sure can be wired to the area in the red box. The middle hole is ground, you'll have to use your DMM to find + and -
 
Again this is just my uneducated guess!
 

 
 
PS: See if you can ask an admin to move this thread into the DIY forum, might get better answers there.

 

[gwillys]

thanks, this is getting interesting. i'll ask over there.
--------------------------------
francis, your right. with line out, 2604 position behind pot has no bearing.
 
actually sounds really good with no opa's

 

[gwillys]

finally, after strugging for months to understand all this, i've had a revelation.
 
after listening to the mini dac for a couple of days with both opamp sockets empty, what i need is a dac with no opa's in the signal path.
this applies to line out, i dont use headphones.
 
i'm thinking the audio gd dac-19 might be just the ticket.
 
the mini dac sounds great/best sans opa's, but there's some noise when adjusting the amp's volume control. i suppose there's a way to overcome this, but its way over my head.

 

[francisdemarte]

I was thinking exactly that when I saw you just had the Aune connected to your amp as a stand alone DAC. The one in the Aune is alright for the price but there are definitely better.
 
If you have the board outside of the case the volume pot is not grounded thats where the noise is coming from. There's a metal ring that goes around the shaft of the volume control it needs to be attached else you can run a wire to the screw in the back of the pot to a grounded source. See #5: http://tangentsoft.net/audio/pimeta/steps.html
 
Check out http://www.headfonia.com/source-2/ for reviews of DACs. Along with Audio-gd I would also look into a DacMagic.

 

[gwillys]

thanks. looks like i'll continue on with this project. if this doesn't work out, i'll quit this modding stuff & buy a good one.
 
 i was having a psu problem, so now i'm back to the burson opa & now a burson regulator. elna caps & mlytic on order.
if recapping goes well, i'll replace the LM1117's with dexa 79xx.
.
i have a burson clock here, but waiting on a 1PPM 12.000mhz tcxo.
 
if i pull this off without breaking something, it should sound pretty good