M2TECH Hiface USB->SPDIF 24/192Khz asynch

[nazar]

If CMOSout levels in practice >0.7-1m

sorry, must be <0.7-1m

[jkeny]

I just noticed this thread now.

I have the Musiland 01US which I have modded as follows:
- powered from external 5V supply (currently SMPS) but will be trying Salas Shunt - best upgrade so far for digital out
- tapped I2S signals & ready to link to external DAC (haven't done so yet for various reasons)
- have just received a Crystek 24MHz clock to substitute for the on-board 24MHz crystal : this will be run off a 3.3V battery
- substituted the op-amp output stage of the PCM1793 DAC with differential Vout direct to transformer: this was the biggest upgrade to the analog out sound.
- I was looking to use a ADUM4160 USB isolator but I'm told that it won't work even at the lower 24/192 speed?

I'll post some pics if anyone is interested.

I wonder how it would compare to the fully modded HiFace? BTW, what chips are used in the HiFace - a Xilinix & Cypress, but what model?

Valeriano, good to see you here - I've been trying to email you but my emails are bouncing back from your old email address.

Guido, any more pics/updates?

[okkyn]

Hi jkeny,

Yes, pleeease post your pictures

[jkeny]

I will but too late now to take pics - will do tomorrow

[Valeriano]

Originally Posted by jkeny

I just noticed this thread now.

- I was looking to use a ADUM4160 USB isolator but I'm told that it won't work even at the lower 24/192 speed?

I'll post some pics if anyone is interested.

I wonder how it would compare to the fully modded HiFace? BTW, what chips are used in the HiFace - a Xilinix & Cypress, but what model?

Valeriano, good to see you here - I've been trying to email you but my emails are bouncing back from your old email address.

Hi John!
how are you? nice to see you (btw my private email is down for maintenance, I'm sending you my regular email address)

ADUM is rated USB/2.0 upto 12Mb/s.. m2tech runs at 480Mb/s so no chance to use it, probably same apply to musiland, don't know. what speed is specd?

btw I modded my m2tech with very good results: i2s out and external 5V from standard regulator+oscon.

I'm doing some more tests, now..I'll post results when completed.

soon
ciao
Vale

[jkeny]

Here are some pics of my Musiland 01US (the one with on-board PCM1793 DAC)
First shot shows the full board which I've done the following to:
- replaced digital PS coupling caps with OSCONS
- analog PS decoupling to PCM DAC with Nichicon Muse
- the Brown & Red wires are from the differential Vout of the DAC to the twin co-ax that connects to a transformer - so this is the new output stage & sounds WAY better than the op-amp o/p stage. I needed to move the two 1K8 smd resistors from their pads (see attached schematic). This now disconnects the op-amp o/p stage but if I want to reconnect I just need to jumper from where the wires are connected to the moved smd Rs. Easily reversible mod. The other channel has thinner wires running under the board. These wires connect to isolated pads that were exposed when the RCA connectors were desoldered from the board.
Last photo shows a close-up of the Xilinx chip where the I2S lines run to the DAC. I removed some of the overlying varnish on these tracks in a staggered manner, applied a touch of flux & solder & then soldered some fine wires onto these tracks (make sure you have tinned the wire & apply some flux to the wire - line it up on the exposed, soldered track & just a tip of a soldering iron will do the job - not difficult with a magnifier. I run the wires through vias, to the bottom of the board and connect to a molex push on connector

[jkeny]

I also put a socket (seen in the pic) on the Vcom pin of the PCM1793 as I heard that this capacitor influenced the sound - I can't say I've noticed much of a noticeable change among caps - maybe a better HF response using film?

I've marked with two red lines, the two 1k8 Rs that are moved down to join with either side of the smd cap, exposing the pads that the two wires are soldered to for the transformer output

[jkeny]

Ok, GuidoR, It's over to you - I showed you mine

[okkyn]

Nice work jkeny!

[jkeny]

Originally Posted by okkyn

Nice work jkeny!

Thanks, I'll report back on my next round of mods:
- Crystek 24MHz clock
- Sescom output transformers
- investigations into battery Vs Shunt regs