discrete dac mock up

[yeo]

hi kevin

i wired them at the output of the dac.

these are 1:1 transformers, also known as bridging or coupling transformers. the sowter i'm using here is sowter 3575, these are spec'ed as 10k:10k. core/shielding material is mumetal.

as these can't take any dc current, you need the buffer's output capacitor to block dc voltage.

in this application, i have also tried the lundahl ll1674, it's an amorphous core. wow! fantastic sonics but have to play around a bit as i got some emphasis on the mids.

yeo

[CKL]

Hi Yeo,

There is no sound with my new XMOS board to the discrete DAC. Should I power the isolated I2S with 3.3V or 5V?

Thanks!

[yeo]

hi ck

discreet monica works with both 3.3v or 5v level inputs.

if you feed data, word select, bit clock and ground correctly, she'll sing.

got the wiring right? does the pc detect your xmos board?

yeo

[CKL]

It works now as the pin1 of RJ45 was wrong. 

[kkerwin]

so yeo,
do you think the waveio is a better source with the discrete monica than the qa550?  bit rate capabiltiy is higher, but qa550 has no moving parts.  what are your thoughts on this?
thanks
k

[yeo]

hi kevin

the qa550, due to only 44.1khz, can not compare with either waveio or the m2tech. it's no comparison bro!

88khz, 96khz and higher sampled material sounds so much better than 44.1khz that it's no comparison at all.

yeo

[kkerwin]

ok,
thx
k

[kkerwin]

hi yeo,
how does the wave io work? my music files are stored as wav files at 44.1khz. does the wave io resample these or do i need to start with different music files?
thx
k

[yeo]

hi kevin

get different music files.

if you play off the mac, the program pure music player could upsample for you. you get "some" benefits of higher sampled material.

best is still to get higher sampled material.

yeo

[CKL]

Hi All,

I have a strange problem connecting my XMOS to the discrete Monica. I hope you can give me some ideas. The connection is perfect with the SPDIF and the isolated I2S but not the non-isolated I2S:

After playing a few minutes, it starts to have some clicking noises. Then, the frequency of happening of the clicking noises increases gradually to an instant all music was covered by the clicking noises. At this stage, if I switch to SPDIF, it is still perfectly fine. To resolve the problem, I have to unplug the power of the XMOS and wait for a while.

The non-isolated I2S is directly from the XMOS chip and there is no buffer.

[yeo]

hi ckl

when the problem happens, can you measure power supply voltage for xmos? i wonder whether there is a voltage drop?

as the xmos draws >0.5a, heat for your regulators could be an issue.

i believe your isolator uses a different supply? as the isolator doesn't draw that high a current, and the fact that it runs off a different supply from the xmos makes thsi possible.

yeo

[CKL]

Hi Yeo,

If I switch the jumper to using 5V from the USB bus, skipping my regulator, the same problem.

[CKL]

My clicking noise problem is solved by replacing the U.FL cables. 

To me, my EVO with clock wins my XMOS!

[yeo]

what's the u.fl cables?

evo with external clock beats the xmos? i'm not surprised!

yeo

[CKL]

The four white cables are u.fl cables. Shielded coaxial cables to connect I2S.