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Mr White's "Opus", designing a simple balanced DAC

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K

korben69

Member
Joined 2006
Hi

I've bought some times ago a second Opus module to a DIYer.
He practiced some experiment on it : no more output caps, bypassed, VRD chip missing, SMD caps saddly hurted...

BTW I'm looking for some advices/hints for the missing part :
1° - Replacing VRD reg : is it 3.3 or 5V chip ?
In both cases, could I swap NS chip with Ti one's ? (same SOT-23 package)
I've got some left from previous USB/DAC.
2° - Output caps : 22uF/16v D:5mm - Lead : 2 mm
Are ELNA OS-Con suitable vs Elna ?

I'll soon add pic of the board ; unexpected, but there's a WM8741 on it ;)
Cheers
 
BrianDonegan

BrianDonegan

Member
Joined 2004
twistedpearaudio.com
korben69 said:
Hi

I've bought some times ago a second Opus module to a DIYer.
He practiced some experiment on it : no more output caps, bypassed, VRD chip missing, SMD caps saddly hurted...

BTW I'm looking for some advices/hints for the missing part :
1° - Replacing VRD reg : is it 3.3 or 5V chip ?
In both cases, could I swap NS chip with Ti one's ? (same SOT-23 package)
I've got some left from previous USB/DAC.
2° - Output caps : 22uF/16v D:5mm - Lead : 2 mm
Are ELNA OS-Con suitable vs Elna ?

I'll soon add pic of the board ; unexpected, but there's a WM8741 on it ;)
Cheers
Click to expand...

VRD is 3.3V. The ti part will probably be fine, as long as it is low drop-out.

These caps will have a big impact on the sound, as they are directly in the audio path. The oscons are fine, technically, but your ears will need to decide on the sound quality.
 
K

korben69

Member
Joined 2006
Thank you Brian for your advices ;)
Yes, Ti parts are LDO, I'll check in the evening the exact ref.
For the caps, I don't know, on my second Opus (WM8740) they are guenuine.
Sorry, I mean Sanyo OS-Con.

What a fast answering delay, BTW I'm late...
Regards

PS : The others SMD electrolytics needed to be replaced too.
I suppose low ESR at this place. I've found NCC Polymer caps, but not in SMD package
 
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K

korben69

Member
Joined 2006
The pic of the Opus module, PCB cleaned, I've done my best...
I've to remove the burnt green terminal blocks.
I prefer direct soldering for signal wire, except PSU.
 

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E

Erlend Sæterdal

Member
Joined 2007
C 5 - 8

I knew you ment them. A pity you can,t buy Black Gate. Its still possible to get some Black Gate Standard at Partsconnexion. They are very soft. Silmic are a bit to bright why don;t you try some Cerafine ? If space are not a problem I have very god experience with Nichicon for speakers. I use them at the input of my power amps ( 68 uf ) I don,t use caps at all at the output of my Opus.

For the analog supply ( 5 V ) I use a Dexa UWB. Maybee I should try that for 3,3 V as well.
 
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K

korben69

Member
Joined 2006
Hi Erlend
Sorry, I don't understand your mean when you say "I knew you ment them." :(

Some BG left around :
100uF/50V x 4 units K type 85°
10uF/35V x 8 units F type 85°
1uF/50V x 8 units K type 85°

The Opus will be used in Balanced mode, feeding an UGS preamp.
I don't know the result with no caps...

VRD is missing, Brian told it's a LDO fixed reg 3.3V not 5V (VRA).
I'm just waiting his validation to replace this with Ti TPS79333DBVR.
 
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tuyen

tuyen

Member
Joined 2008
Paid Member
using transformer output on the Opus DAC

Got a custom pair of Bud Purvine's o'netics line transformers on the way. Data sheet as attached to this post.

I want to use it to convert balanced to unbalanced signal from my Twisted Pear Opus DAC that uses the wolfson WM8741 chip (datasheet: http://www.wolfsonmicro.com/documents/uploads/data_sheets/en/WM8741.pdf)

Schematic for the Opus: http://www.twistedpearaudio.com/docs/digital/opus_schematic.pdf

My question is, do I need to load the primary or secondary windings with any resistors and/or add any capacitors for any filtering?

Can I also pick the signal before the output 4 elna output caps/resistors on the opus board?

Cheers!:)
Tuyen
 

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H

HAL2010

Member
Joined 2007
tuyen said:
Got a custom pair of Bud Purvine's o'netics line transformers on the way. Data sheet as attached to this post.

I want to use it to convert balanced to unbalanced signal from my Twisted Pear Opus DAC that uses the wolfson WM8741 chip (datasheet: http://www.wolfsonmicro.com/documents/uploads/data_sheets/en/WM8741.pdf)

Schematic for the Opus: http://www.twistedpearaudio.com/docs/digital/opus_schematic.pdf

My question is, do I need to load the primary or secondary windings with any resistors and/or add any capacitors for any filtering?

Can I also pick the signal before the output 4 elna output caps/resistors on the opus board?

Cheers!:)
Tuyen
Click to expand...

You will not need the output coupling caps and resistors. Just jumper the output cap locations on the PC board to get the signal to the output pads and connect the transformer.

The question is what is the input impedance of the preamp it will feed? It should not be low.
 
V

vitalbesson

Member
Joined 2009
Hello,

I would like to ask - may I use Opus DAC with the system that is not always generate I2S signals? For example, many AKM chips required to have reset signal while I2S is silent... I can not find out if WM allow silent I2S chain, without any additional management/signals, is this possible?

Also, how would you judge codec itself - is this about the same level as AK4396?

Thanks!
 
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