[danny_66]

Thanks for being the pioneer
I just ordered a Musiland monitor 02 US and a 01 USD.

Sounds like a good method for tapping of I2S, just make the two wires that have the shortest trace to the FPGA a little longer. Don't heat the PCB too much or the traces can otherwise peel off.
Success!

 

[mmerrill99]

Oh, BTW, this is a well made pcb - I did some soldering on it already - very robust - nice groundplane on the underside split into digital & analog areas.

Let us know of your progress!

 

[glt]

Jkenny, have you looked at the power regulation? I can see there is 3.3 and 1.2, is the opamp using 5v straight from USB? The 4 nimh batteries are 5.5 when fully charged and no load. I suppose this is safe... (It is .25v beyond usb max power spec)

 

[donunus]

Quote:

Originally Posted by macrog /img/forum/go_quote.gif The sound quality from the monitor 02's analogue outputs is a noticeable step up from my Dacmagic when fed a usb source even on 44.1khz recordings with more detail apparent.

Monitor 02 is better than the dacmagic via usb? Just wondering what other dacs have you tried? Do you think I should go with the musiland over an emu0404?

 

[mmerrill99]

glt,
you're safe - 3.3V & 1.2V are provided through regulators (Vin is +5V from USB). PCM1793 has VCC of 5V (max of 6.5V) & VDD of 3.3V; OP275 has bipolar supply of + & - 5V (max +&- 22V). Batteries should be very nice - I haven't tried yet.

I've been experimenting with PCM1793 Vcom cap (I took out 1uf Wima & put in a socket). Those on Diyhifi.org say low leakage, high capacitance is best - no film caps need apply (of course their opinions differ) - too early to say yet - Electros tried so far Panasonic FC, Silmic, Elna, Blackgate (C, NX, STD, non-polar), Philips - will try Muse &some others tomorrow as well as film.

Should be testing it against a Beresford DAC tomorrow also.

 

[TheShaman]

So, jkeny, the way to go for external power is not to cut the GND cable altogether but just expose it so you can solder an extension cable that'll go to the external regulator?

 

[mmerrill99]

Here's my cable diagram - hope it's clear

 

[TheShaman]

Ok, no cutting of GND wire.

 

[mmerrill99]

The ground wire needs to come straight through from the PC because it is used as a reference for the signal wires - so just connect the new external supply ground to it also.

 

[mmerrill99]

I tried 4*1.2V NiMh batteries (4.9V) but probably slightly prefer the SMPS which gives out 5.06V at 2 Amp. I think I'll have to give a good 5V shunt regulator Salas) a go.

Vcom - seems to respond like signal passing caps - film caps for the clearer highs but need higher uF for decent bass response. I don't have any high uF film caps so trying some electro or MKT uf with small value film bypass cap.

No Beresford comparison - the guy forgot the DC PS for it!

Rigged up a USB socket that accepts external PS - easier & neater than hacking into USB cable

 

[denydog]

I've been following this thread with interest, but some of you are getting out of my league with the mods, though I can see what you're trying to do.

I ordered a monitor 01 USD last night. my hopes for it are modest, and I think pretty common.

First off, I just want to feed PC based music to my Grace m902 using other than its USB input, which has a reputation for fairly high jitter. I'm hoping this will result in an overall improvement in sq, even with the Internet radio I've come to enjoy. Secondly, this will also allow me to play some of my music files with higher rez than 16/44.1-48

I have been considering the Bel Canto converter for some time, but it's a lot of money just to see if I'd like it. The 01 USD is a lower stakes gamble. I've been encouraged by some of the reports and comparisons I've read on this thread, and will look forward to more.

 

[tosehee]

Quote:

Originally Posted by denydog /img/forum/go_quote.gif I have been considering the Bel Canto converter for some time, but it's a lot of money just to see if I'd like it. The 01 USD is a lower stakes gamble. I've been encouraged by some of the reports and comparisons I've read on this thread, and will look forward to more.

You are exactly on the same boat as me. I am debating whether I should get this or not, but still holding onto it because I see several conflicting reports.

 

[mmerrill99]

Here's what I've done so far and I must say the sound of this 01 US is stunning
- replaced capacitors on digital 3.3V with Oscons
- put in some extra capacitance where USB comes onto the board
- put some extra capacitors (10uf) at the PCM1793 supply pins
- put a socket in place for Vcom so I can experiment with different capacitors
- put Oscon caps across the input & ground of both regulators

Great improvement in sound when running from external power supply
Vcom capacitors seems to act like signal passing capacitors so big capacitance needed for good bass but film capacitor needed for clean high frequencies. Still experimenting.

 

[glt]

jkeny,

"- put in some extra capacitance where USB comes onto the board"

Is that across the 5V?

 

[glt]

I just did a comparison between usb power and battery power. Can't tell if there is any difference... (94/24 material in iTunes for windows, Lenovo laptop, headphone output, HD580). This means USB power filtering is pretty good...