XMOS-based Asynchronous USB to I2S interface

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J

JLOP

Member
Joined 2011
What i2S connectors & cables

Hi all

To connect the Wave IO board to my DAC AD1865 NOS SRPP (which has no connector yet and when Lucian will have done the software update to allow for RightJustified I2S this DAC has :vampire:), I am looking for advices :
- what connectors (DEP, 8P8C RJ45, ...) ?
- what cables (shielded, not shielded, CAT5 or 6, flat, ...) ?

Thanks
Jean-Louis
 
J

jrling

Member
Joined 2010
LiFePO4

luisbock said:
Lifepo4
Click to expand...

I do agree that they are the best battery power technology, but the cells are 6.6v (2S) and we want 5.0VDC for the WaveIO.

So some sort of regulation will be required.

The phone charger type LiPOs do output at 5V and would have no charger noise if not plugged into the mains. So convenience factor very high and effectively Plug 'n Play.
 
M

mevang

Member
Joined 2004
I am connecting the I2s output of the WaveIo board to the I2S input of a Buffalo II DAC. I know that a mod is required to feed the buffalo II with the master clock.

1) What benefit can I expect from feeding the DAC with the WaveIO master clock?

2) Is it necessary to connect the WaveIO master clock to the Buffalo (i.e. do the mod) to have the USB->I2S conversion work in true asynchronous mode ?

Thanks a lot.
 
Last edited:
H

hochopeper

Member
Joined 2009
Sandor said:
I am connecting the I2s output of the WaveIo board to the I2S input of a Buffalo II DAC. I know that a mod is required to feed the buffalo II with the master clock.

1) What benefit can I expect from feeding the DAC with the WaveIO master clock?
Click to expand...

Hard to say ... it depends really. From what I have read mostly the benefits come if you are able to provide a high freq master clock, closer to 100MHz. With the WaveIO clocks you won't get high enough for it to be worthwhile IMO.

Sandor said:
2) Is it necessary to connect the WaveIO master clock to the Buffalo (i.e. do the mod) to have the USB->I2S conversion work in true asynchronous mode ?

Thanks a lot.
Click to expand...

If you don't mod the BII and just connect I2S without the mclk from the WaveIO you will have asynch (clock is provided by the one mounted to the BII).

The mod is required for synchronous mode.
 
B

barrows

Member
Joined 2010
Welll...

Sandor said:
I am connecting the I2s output of the WaveIo board to the I2S input of a Buffalo II DAC. I know that a mod is required to feed the buffalo II with the master clock.

1) What benefit can I expect from feeding the DAC with the WaveIO master clock?

You will have to listen and see. Synchronous clocking disables the asynchronous sample rate converter and the DPLL. So it allows the digital data to go direct to the oversampling filter and delta sigma modulator of the ESS chip unchanged. I generally do not like the sound of asynchronous sample rate converters (although the ESS' sounds a lot better than most others to me) and feel that synchronous clocking with my B-II sounds more natural. The clocks on the Wave IO will work with the proper spec from ESS for data rates up to 24/96, according to ESS, it would be better to have x2 clocks for 176.4 and 192 rates, but it will work fine with the clocks on the Wave IO. I am running my B-II in synchronous mode from clocks of the same rate as those on the Wave IO, and I like the sound better than running the B-II using the onboard MC. The previous poster's advice concerning 100 mHz clocks is not correct, as that rate is for running the ESS in asychronous mode. But according to ESS, it would be "better" to have 2x clock rates for 176.4 and 192 (and 4x rates if one is trying to playback 352.8 and 384 files)

2) Is it necessary to connect the WaveIO master clock to the Buffalo (i.e. do the mod) to have the USB->I2S conversion work in true asynchronous mode ?

The Wave IO interface will always operate asynchronously regardless of how you provide clocking to the ESS chip itself. The difference is: if you run the B-II using the onboard master clock, then the DAC chip itself has its asynchronous sample rate converter active, if you run the B-II using an external masterclock from the Wave IO, then the onboard clocking of the DAC chip is synchronous, that is, the masterclock and bit clock are synchronous with each other and the asynchronous sample rate converter will be inactive. Either way, the Wave IO is still operating asynchronously.

Thanks a lot.
Click to expand...
 
qusp

qusp

Member
Joined 2009
it doesnt bypass the pll and go straight to the modulator, nothing changes internally in the ESS, there is no switch, no change in the signal path, its all the same, but if running synchronously it just effectively has nothing to do. the DPLL is 'freewheeling' to use Dustins words. also hochopeper said closer to 100MHz, not actually 100MHz. I guess he just couldnt be bothered typing out the exact numbers of 90.3168Mhz/98.304MHz (<-pretty close to 100MHz dont you think?)
 
B

barrows

Member
Joined 2010
Right...

qusp said:
it doesnt bypass the pll and go straight to the modulator, nothing changes internally in the ESS, there is no switch, no change in the signal path, its all the same, but if running synchronously it just effectively has nothing to do. the DPLL is 'freewheeling' to use Dustins words. also hochopeper said closer to 100MHz, not actually 100MHz. I guess he just couldnt be bothered typing out the exact numbers of 90.3168Mhz/98.304MHz (<-pretty close to 100MHz dont you think?)
Click to expand...

right: because the masterclock and the bit clock are synchronous, both the onboard ASRC and DPLL do nothing to the data, so the data passes through those parts of the DAC chip without being changed at all. Hence, it is the same as if there was an internal "switch" actually changing the signal path.
As I said-the data goes straight to the OSF and DSM without being changed by the ASRC and DPLL.

The ESS spec calls for the clock rate to be >192 fs, so for a 192 sample rate that means >36.864 MHz, quite a bit lower than the 100 MHz he mentioned. To meet ESS specs for best operation at up to 192 (the highest rate wave IO allows) 2x clocks would be totally fine: 45.158 and 49.152, not close to 100 MHz at all. That being said, I am running an XMOS based async interface, with 22.579 MHz and 24.576 MHz clocks, the same as the Wave IO's, and it works fine (and sounds better synchronously) with music playback of files at sample rates up to 192. According to ESS, it should sound even better with 2x clocks, I have not heard that yet, but still running the B-II synchronously even with the lower rate clocks sounds better than using the onboard masterclock.
Now, if one wants to meet the ESS data sheet, and support sample rates up to 384, then a masterclock "around 100 MHz" would be required (4x rate, or >192*384=>73.728 MHz). But the Wave IO does not support sample rates above 192.
My point is, that one should not be discouraged from trying synchronous clocking with the Wave IO's standard clocks, they meet the ESS requirements for rates up 96 KHz, and they will also work fine for rates up to 192 KHz. Listen, and decide for oneself.
 
B

Blitz

Member
Joined 2002
One doughter board please for me as well:

1. hirez69
2. analog_sa
3. m.massimo
4. ozlegend
5. luisbock
6. vitalica
7. palmito
8. gabanyayaya
9. danny_66
10. shoom
11.12. kp93300 X 2
13. lindamar
14. merlin el mago
15. Reo
16. arkadiush1
17. jmltinc
18. zibra
19. tagheuer
20. hochopeper
21. hacker
22. Bemused
23. vanwykca
24. sandor
25. jrling
26. bismuth
27. necplusultra
28. flocchini
29. ichiban
30. edbk
31. Nikon1975
32. pawlus
33. dubai2000
34. henri47
35. presapian
36. Corpius
37. Ryssen
38. carsten.witt
39. Sidiropa
40. Ryelands
41. krautxy
42. 43. 44. 45. Mats x 4
46. ecchecequa
47. 48. lm1no2 x 2
49. Magsy
50. Jogi
51. CKL
52. needsp
53. number9
54. steve jones
55. nuriasanta
56. miksi
57. audiodesign
58. hordmop
59. cjunkk
60. Thermio
61. dex-rex
62. & 63. Claudius J. x2
64. boggy62
65. sck2288
66. rjbaldwin
67. ravid
68. igor
69. neugruen
70. Miclaud
71. Luxury54
72. mjock3
73. JLOP
74. Stixx
75. CeeVee
76. Blitz
 
L

Lorien

Member
Joined 2007
luckit.biz
Ryssen said:
When will there be a price hint so one knows if I should order 2 boards...:)
Click to expand...
As I said in my previous posts, your name placed there will not force you to buy any of the boards if you don't want to so there's no reason to worry about the price or anything else as you, and all others on that list, have the freedom to decide if you'll buy it or not when it will be ready. :)

merlin el mago said:
Lucian, are you preparing the firmware upgrade to play DSD?
Cheers
Felipe
Click to expand...
Unfortunately not for the moment as I have two other boards to work on (including the daughter card) but soon enough it will happen. Anyway, I'm quite strange on how XMOS works and I guess I'll learn about it in the same time. :eek:
Cheers,
L
 
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