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Old 15th December 2012, 05:21 PM   #161
regal is offline regal  United States
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Quote:
Originally Posted by linuxworks View Post

my plan is to try controlling the 2 wolfson dac chips via software, so I have to 'edit' the board a bit to convert it from hardware mode to software mode. TBD.
Did you see Hifidino's latest blog where he says his WM8741 code never worked! Something about 8bit registers being sent as 7-bit. He said the controller will go thru the motions but nothing really changes, this is like 2 years after the fact

If you notice the commercial assembled Wieliang version of this DAC7 is software controlled (its the $350 oe seen on ebay, sold by Valaab also). You can pick all 5 filters at each samplerate, however the reviews I've read say they can't hear a difference in filters. Makes me wonder if Wielang is using a copy of the faulty Hifidino code


Regardless the DAC7 board software controlled would be a real nice setup, just wish the usb module did 176.4 kHz.
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Old 15th December 2012, 05:41 PM   #162
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I am going to write my own 8741 from scratch, so I'm actually avoiding looking at other sources

I don't think the dac7 is software controllable in its present form. the pins are hardwired to hw-mode. there's no port for i2c or anything. maybe the dual 8741 is on some other board with a controller, but this one is hw-only and there's no easy way to adapt it (hack it, yes, but not meant for it by design).

for usb, I am perfectly happy with usb/spdif and then taking spdif in via any old dac. the usb audio widget or other will handle that task. embedding usb on a dac seems wrong to me; like combining things that would really better be left as their own boxes.

the usb to spdif converter is almost more part of the pc, in my view, than part of the dac. and my HTPC that is at least 2 yrs old has spdif-out on the mainboard and its bit-perfect (they all are, these days, to be dts/dd5.1 compliant) and it runs up to 192k.

the problem with the wolfson spdif receiver in hw-mode, though, is that it won't pick up 176k. the rest SRs should be ok but 176 can't be told from 192 when the chip tries. you have to tell the chip to try one, see if its locked on and if not, try the other. or 'know' via other means what rate it is and then tell the receiver chip to set its pll's and dividers as such.
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Old 19th December 2012, 07:03 AM   #163
gugi100 is offline gugi100  Netherlands
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I have a couple of questions?
- how is the source changed?
- does the cm6631 module feed I2S to the wm8741 or spdif to wm8805?
- what is the function of the switch?
- what is the difference between V1.0 and V1.01?


Greetings
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Old 19th December 2012, 05:53 PM   #164
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I can answer that about the dac7, but not about dac5 (don't have dac5).

source is changed via a switch. its not even a logic switch but data actually goes thru it. not the best idea, really.

usb feeds i2s in. the riser module has access to i2s bus, so that's clear.

I would avoid the cmedia 'high speed' modules for now. there are new ones (fixed ones!) coming out soon and cmedia needs more time to be production quality. my 2cents...

I would handle usb/spdif outside this dac. then simply send in spdif from your external usb adapter.

spdif is not a problem and the whole world uses it. no need to go i2s when spdif is a perfectly usable interconnect.
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Old 19th December 2012, 07:57 PM   #165
gugi100 is offline gugi100  Netherlands
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Thank you for the answer.
Forgot to ask the red dipswitches, do you know what these do?

Gr GJ
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Old 19th December 2012, 08:17 PM   #166
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yes, they set the dac hardware filter flags, relating to samplerate range.

2 since one is for each dac chip.

there should have been more switches. anti-clip, for one. pin26 is left floating or grounded and I prefer to have the 2db anti-clip feature on, so that means lifting or never soldering down pin26 of the 8741 chip.
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Old 27th December 2012, 08:43 AM   #167
maxlabt is offline maxlabt  Ukraine
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Hi Weiliang!
I bought DAC7 v.1.0.
I ask you to send me a diagram of versions 1.0 and 1.1.
I want to see the changes and make revisions.
My email maxlabt@mail.ru
Thank you.

Last edited by maxlabt; 27th December 2012 at 09:03 AM.
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Old 28th December 2012, 05:43 AM   #168
regal is offline regal  United States
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Quote:
Originally Posted by linuxworks View Post
I am going to write my own 8741 from scratch, so I'm actually avoiding looking at other sources

.

Well do share. I would love to see a full I2C control for the wolfson, its a shame no one has really put the effort into this fine sounding dac chip that it deserves.
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Old 3rd January 2013, 06:38 PM   #169
gugi100 is offline gugi100  Netherlands
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Is there anyone who has the scematics of the dual WM8741 board? Please PM them to me. I PMed wieliang two weeks ago but didnot get an answer. Asembling the board wil be a lot easier with scematic...

Gr GJ
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Old 4th January 2013, 12:54 AM   #170
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Well do share. I would love to see a full I2C control for the wolfson, its a shame no one has really put the effort into this fine sounding dac chip that it deserves.
I might do some of the code; or AMB might do the coding. I know he's planning a DIY dac of his own and I know, for certain, that it will be open-source arduino based.

one way or another, some code will get out there and people will be able to play.
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