Open-source USB interface: Audio Widget

[alexlee188]

Hi Wei, John et al,

I would agree that the present arrangement of clocks of the USB9023 board is probably a good one, for the following reasons:

1. The "time domain jitter reduction" mechanism with a high (50Mhz+) MCLK is useful if the source signal has high jitter (eg SPDIF input). However, I suspect this mechanism involves some form of re-sampling within the ES9023.

2. With our async out arrangement and direct clocking of the ES9023 with a low jitter clock, no resampling of any form is done at all, and we are already assured of low jitter.

When we have a listening A/B test comparing the USB9023 (modded by Wei) and an ACKO 9023 board, we will know which clocking scheme is superior :-)

Alex

[borges]

Hi Alex,

I belive the clocking on AB-1 can be made even better. I have been modifying an AB-1 board to skip the Maxim MUX and rather use the EN pins of the Golledge XOs to select the frequency. This is a fairly easy fix because the footprints are there on the AB-1. I'm currently testing this setup for long-term stability. But everything this far tells me I'll use it for the next production batch of AB-1. Let me know, and I can tell you all the details. The benefit of this MUXing method is to reduce the capacitive load and power coupling seen by the XO outputs.

Any input on ES9023 cap and resistor size is welcome. I'm happy to hear about tweaking efforts. AB-1 was designed to be functional and a good platform for simple mods.

Børge

[2A3SET]

Hi jkeny,

Minimalist player uses WASAPI, buffering whole file into memory first,
Minimalist Audio Player
I guess similar idea as soundcheck's instruction under linux,
Linux Commandline Player - diyAudio

I swaped capacitors one by one (use USB bus power and directly driving HD600), most improvement is the pump capacitor. I also tried clean external power to feed ADP-151, the improvement is there, smoother sound and darker background, while USB bus power is not that bad. It's worth try to bypass ADP-151 using Lifepo4 battery or Salas shunt.

Originally Posted by jkeny

What is the minimalist(andy) audio player?

You noticed much improvement with upgrading these caps? Did you do them one at a time & note dthe change or in two groups as you said? Supplying a cleaner power to ADp151 will improve it

[2A3SET]

Audio-widget is using dual rate XO (22.5792/24.576M) to feed ES9023 directly, with FF to feed 1/2 rate clock to Atmel chip. I am wondering if it worth to use higher rate XO 45.1584/49.152M, with lower jitter FF (SN74AUP1G7) to get 1/4 clock.

Originally Posted by jkeny

Best solution, I believe, is a local clock at the DAC synchronised back to the transport

?

[2A3SET]

I guess the I2S output from Atmel is not 100% aligned with the XO clock, so it may benefit by reclocking them using idea from John's design at "ultimate TDA1541 DAC", maybe ES9023 has similar function built in already.

Originally Posted by alexlee188

Hi Wei, John et al,

I would agree that the present arrangement of clocks of the USB9023 board is probably a good one, for the following reasons:

1. The "time domain jitter reduction" mechanism with a high (50Mhz+) MCLK is useful if the source signal has high jitter (eg SPDIF input). However, I suspect this mechanism involves some form of re-sampling within the ES9023.

2. With our async out arrangement and direct clocking of the ES9023 with a low jitter clock, no resampling of any form is done at all, and we are already assured of low jitter.

When we have a listening A/B test comparing the USB9023 (modded by Wei) and an ACKO 9023 board, we will know which clocking scheme is superior :-)

Alex

[mace1337]

I kind of lost track of this project. How are we on board availability?

[alexlee188]

Hi mace1337,

George still has 11 bare USB9023 boards (as shown in 2A3SET's photo), and he has parts for 3 sets. Borge is planning another run of his AB-1 boards.

You can contact George at:

george.boudreau@gmail.com

Alex

[jkeny]

Originally Posted by 2A3SET

Hi jkeny,

Minimalist player uses WASAPI, buffering whole file into memory first,
Minimalist Audio Player
I guess similar idea as soundcheck's instruction under linux,
Linux Commandline Player - diyAudio

Thanks, I'll try it & check if it's better than PurePlayer

I swaped capacitors one by one (use USB bus power and directly driving HD600), most improvement is the pump capacitor. I also tried clean external power to feed ADP-151, the improvement is there, smoother sound and darker background, while USB bus power is not that bad. It's worth try to bypass ADP-151 using Lifepo4 battery or Salas shunt.

I'm wondering if the capacitor change is helping to suppress the noise on the USB supply? Maybe if you tried the LiFePO4 battery first you may not have noticed much of a difference with the cap changes - I don't?

[stew1234]

Originally Posted by alexlee188

Hi Blushift et al,

U are welcome to try writing a windows uac2 driver as well :-). The more alternatives we have the better.

As I mentioned before, it is technically possible to write a windows uac2 driver that works with a single audio device. There are several commercially available drivers around. However, AFAIK, no one has written a driver that can work with a composite USB device that has uac2 plus something else eg HiD.

Async out is the most desirable mode for bit perfect low jitter transfer, but u might like to start with simpler modes first in the driver development.

Native uac2 support is available with OSX and Linux now. I am waiting for support under Android, which should happen soon as the Linux kernel is used in Android.

I think we will have working windows uac2 from Tsai or u much sooner than M$. It is nit that they are not smart enough to do it - it is the motivation or lack of :-)

Alex

When you mention you're waiting for uac2 support under android does that mean in the future it might be possible to use an android phone (or even better a honeycomb tablet) as a usb source to plug into the module?

[alexlee188]

Yes. Android phone/tablet as USB host. Current Android hosts already support simple USB devices such as mouse and keyboard. Uac2 driver that works well is only available in Linux kernel 2.6.37 or later and has not made it to Android yet.

Alex