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

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#1,681
Transformer for BAL to SE conversion

I have a couple of Lundhal 1:1 LL1527XL transformers that I intent to use for Balanced to SE conversion for a single board Opus. Does anyone have experience with such a configuration? I’ve tried to connect directly the primaries to the DAC output and while initially sounded OK, gradually I’ve started having distortion that was getting higher with time. On page 65 revintage says that series-resistors are needed when connecting the DAC directly to a transformer. If this is the only way to go, could someone please help on calculating the needed resistance value? Above is the datasheet of the transformer.

http://www.lundahl.se/pdfs/datash/1527_7xl.pdf

Thanks in advance,
Tassos
 
#1,683
How to reduce output level

Hi! I've got two Opus boards in dual differential mode. It has apr 4V output. What should I do to reduce this to about 2V?? Guess it is as simple as putting some resistors from the + and - leg to ground, but I have no idea wich value to use. Any suggestions??

Stein
 
#1,685
a question

i have read the whoe thread but still i have a question...

in Opus dac Mr.White is using CS8416 input receiver.. i have cs8414 receiver. from what i know those two are not exactly pin compatibile. am i right?
how to implement cs8414 in Opus dac? can somebody explain this to me nice and easy because i am not very good in digital.
thnx.
regards
sunny.
 
#1,687
well, i am not good in digital. but i think that i figured everything out. thnx.
i have to use 8414 as it is used in TDA1543 dac's but i only have to use pin 19 of the 8414 for SCKL on wm8740. i think that is the difference. everything else is the same since cs8414 is converting spdif into i2s as used in TDA1543.
 
#1,690
I have questions about the WM8804 opus receiver:

I am using this to receive SPDIF and output I2S to the Opus DAC.

1. As setup according to the manual (http://www.twistedpearaudio.com/docs/digital/wm8804_2.0_manual.pdf), is it capable to accept SPDIF signals in 16/44.1, 24/96, 24/176.4, 24/192 and output I2S with the same bit length/sample rate?

2. Does the WM8804 module automatically detect the incoming sampling rate, or is there anything that need to be setup when using it for 16/44.1, then 24/192 for example? Looks like there are 4 different modes of operation depending on what kind of bit length/sample rate received (page 27 of date sheet http://www.wolfsonmicro.com/uploads/documents/en/WM8804_Rev4.5.pdf). Does the WM8804 module automatically switch between these different modes, or is it only setup to run at one of these modes?

I am playing FLAC files with SPDIF output from my sound card from 16/44.1 to 24/192, and I am wondering whether my WM8804 receiver is capable to accept all these different sample rates and output the same through I2S.

Thanks!
 
#1,691
kop89 said:
I have questions about the WM8804 opus receiver:

I am using this to receive SPDIF and output I2S to the Opus DAC.

1. As setup according to the manual (http://www.twistedpearaudio.com/docs/digital/wm8804_2.0_manual.pdf), is it capable to accept SPDIF signals in 16/44.1, 24/96, 24/176.4, 24/192 and output I2S with the same bit length/sample rate?

2. Does the WM8804 module automatically detect the incoming sampling rate, or is there anything that need to be setup when using it for 16/44.1, then 24/192 for example? Looks like there are 4 different modes of operation depending on what kind of bit length/sample rate received (page 27 of date sheet http://www.wolfsonmicro.com/uploads/documents/en/WM8804_Rev4.5.pdf). Does the WM8804 module automatically switch between these different modes, or is it only setup to run at one of these modes?

I am playing FLAC files with SPDIF output from my sound card from 16/44.1 to 24/192, and I am wondering whether my WM8804 receiver is capable to accept all these different sample rates and output the same through I2S.

Thanks!
Click to expand...
1) it will accept all but 176.4khz at both 16 and 24bit depth because of the way the WM8804 works in hardware mode.
2) It does auto detect. Nothing special is required.
 
#1,692
Have mine up and running, MUX>METRONOME>OPUS>IVY. Soundws very, very nice. Trying to get the volunmite to work but no go so far. What switch settings do I use to get into Software mode and which wires go where from volumite to opus? Thought I had it right, but got nothing out>
 
#1,694
WM8804 vs. CS8416

Russ White said:
1) it will accept all but 176.4khz at both 16 and 24bit depth because of the way the WM8804 works in hardware mode.
2) It does auto detect. Nothing special is required.
Click to expand...

Twisted S/PDIF receiver vs. the 4:1 mux/Receiver
-- I don't think I need more than one input, and I don't have an issue with the above 176.4kHz issue.

Anyone have any experience with which setup sounds better? Is the 8804 any better than the 8416? I suppose they both have fairly good jitter rejection, so shouldn't sound much different. -- BTW, I don't plan to use a metronome. (for now at least)

That leaves me tempted to get the 4:1 just to have the transformer inputs, and the extra flexibility. Still, I'm worried it might not sound as good as the wolfson receiver. (if I'm crazy, just say so 😉 )

hmm, just noticed the 8416 on the mux isn't using an external clock. That seems to favor the 8804. If the 8416 is using only the recovered clock. ???
Any thoughts, comments, experiences?

Thanks!
 
Last edited:
#1,696
glt said:
The 8804 has better jitter specs (50ps), the 8416 I I think it is 100-200ps
Click to expand...

Thanks glt. That's what I thought, but haven't had a chance to lookup and thoroughly compare the 8416 DS.

I found a few more comments around here and it seems the 8804 is the way to go. looks like I'll go with the S/PDIF receiver (8804) -> OPUS (8471) -> IVY

BTW, that's some really nice work with the uC. I like those little Arduino boards. I have a little one here I've been meaning to put to work for some time. You've got a good looking little setup.
 
#1,698
some problem with opus

Hello, I need some help for a crackling noise from both channel.
I use a dual mono Opus 8740 with SPDIF receiver. Power supply is 8Vcc regulated for both module and for both VA and VD.
The system has been working well for over six months until a couple of days ago when the problem started in the middle of a listening session. No intervention was made before. Now it persists every time I turn Opus on, cold or warm condition.
I use a se output tapping +/GND, but I tested -/GND with no relief.
I tested the DAC with two different transports (same problem) and the amplification with a different CD player (no problem).
I tested the two DAC separately in stereo mode and the problem persists for both. Unfortunately I haven't got a I2S source so I cannot exclude the receiver.
If I pause the CD, the crackling noise stops and then restarts when the music flows again.
Please listen
http://www.webalice.it/mmassimo3/Opus_1kHz_-70dB.wma
http://www.webalice.it/mmassimo3/Opus_1kHz_-100db.wma
http://www.webalice.it/mmassimo3/Opus_1kHz_-0db.wma
-70db and -100db are recorded with preamp volume very high, 0dB with normal volume level.
sorry for the very low quality microphone (a PC type)

Any suggestion?
 

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