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|30th March 2009, 04:58 AM||#1|
cMP2 DIY Mods...
This thread is to provide a place to discuss modifications to and DIY solutions for building a cMP2 computer music player, as designed by cics.
See more info on the cMP2 hardware and software here:
cMP-Squared Main Audio Asylum Thread
cPlay Main Audio Asylum Thread
This setup is a sound-quality-first setup...specific hardware and software configuration, no networking, no other programs running on the computer, most of Windows removed or shut down, etc.
If you're into a super-convenient play-music-everywhere computer music server, this is NOT the system for you.
But if you want the best sound quality you can get from a computer (and don't mind wearing a hair-shirt to get it!), you need to check this out.
Interesting mods will include things like:
- Modified or scratch-built computer power supplies
- Motherboard modifications
- Sound card modifications
- Alternative configurations (like Peter Daniels USB-DAC setup)
- Vibration, RF, & EMI control techniques
- AC power filtering
To kick things off, here's some modifying I did to my Juli@ sound card this weekend
|1st April 2009, 02:10 PM||#3|
Now that the prices are coming down for Solid State Disks it
will be interesting to see how they perform.
One thing for sure - they're silent, and they are more efficient than even the small notebook hard drives.
The big trade off is lack of storage space though.
SUPER TALENT MasterDrive OX FTM16GL25H 2.5" 16GB $75.00
|2nd April 2009, 07:14 AM||#4|
Join Date: Oct 2004
i'm using a CMP + CPLAY with a CICs optimized PC. Switched off upsampling in CPLAY as the DAC does it anyhow.
Motherboard mods :
- CPU Powersupply line, Common mode chokes and 1000uF added per line
Julie mods :
- Only using the digital part of the card
- Replaced the 3.3V regulator with a shunt regulator (better than batteries)
- IS2 out to external DAC
DAC setup currently :
- Twisted pears Sabre with batterie supply, I2S input
(This makes a huge change there)
- Luhndahl passiv out
- VREG mod with shunt regulator
currently waiting for my Counterpoint I/V to give it a try, this will be powered with a Jung style regulator.
|3rd April 2009, 01:48 PM||#6|
Join Date: Oct 2004
the VIA chip runs at 3.3V which is done with a cheap SMD regulator on the edge of the Julie card itself.
You simply unsolder that regulator and connect any shunt reg you want to to the solder joints and glue it to the back of the card.
There are several designs available in the forum, or if you are lazy just by them ready made.
the biggest advantage of the Julie is the design and the good drivers, it is so easy to mod. For I2S you do not need to fiddle around mit SMD soldering, simply connect it. However if you use the stock card, it is total crap especially the SDIF output.
|4th April 2009, 01:04 AM||#8|
Re: cMP2 DIY Mods...
In the light of the quote below, how about taking I2S from Julia@ and connecting directly to TDA1543 in my DAC? If that works well, I might finally get Julia@ myself for such a configuration
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
|4th April 2009, 03:10 PM||#9|
Re: Re: cMP2 DIY Mods...
Hmm... I have a Peter Daniel DAC sitting here doing nothing right now... I may have to hook that up myself.
I posted a compiliation of a lot of information on the Juli@ on the AA, bringing together information from a bunch of posts on different boards. I'll repost that here.
Greg in Mississippi
|4th April 2009, 03:15 PM||#10|
What prompted this is the imminent arrival (I hope) of an I2S-connected DAC. It's not a commercial product, but just a tweaked set of boards as used by one of the EQ modifiers. I'm hopeful that this DAC will work well driven by the Juli@ as it is based on the AK4399, a similar DAC to the AK4358 that's already used in the Juli@.
I needed to find the reset pin in the J3 header, one that I haven't found identified in previous posts on various forums in the past. So I pulled out my trusty meter and started poking around... and then wanted to confirm some of the other pins... and then find the +-12v pins... And then kept going... and this is what I found:
J3 connector signal pinout (note much of this is taken from the Head-Fi post http://www.head-fi.org/forums/f46/ea...d-card-242285/):
J3 Pin 1 -> 1724 PSDOUT ( I2S data out) -> AK4358 SDTI1 (I2S data in)
J3 Pin 5 -> 1724 PSYNC ( I2S Word Clock ) -> AK4358 LRCK (I2S Left/Right Word clock)
J3 Pin 7 -> 1724 PBCLK ( I2S bit clock out ) -> AK4358 BICK ( I2S bit clock in )
J3 Pin 9 - > Xilinx on the digital board -> AK4358 MCLK ( I2S Master Clock in )
J3 Pin 11 - > Xilinx & AK4114 on the digital board - > AK4358 PCN (Reset)
J1 connector power supply pinout (note much of this is taken from the Head-Fi post cited above and some is taken from this Asylum post http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=35497):
J1 Pins 1 & 3 -> +12v
J1 Pins 7 & 9 > -12v
J1 Pin 2 -> +5v
J1 Pin 10 -> +3.3v
J1 Pins 4, 5, 6, 7 -> grounds
PCI power supply connections (note some of this is stated in this Asylum post http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=35497 . Also, a good source for the PCI pinout is here http://pinouts.ru/Slots/PCI_pinout.shtml):
First of all, the Juli@ only uses the +5v and +-12 lines from the PCI bus. If you look carefully at the pins specified as 3.3v on the Juli@ edge connection, you'll see that the conductive fingers are not connected to the board. This simplifies hooking the Juli@ up to a separate power supply... here's the PS pins:
B1 - > -12v
A2 - > +12v
B5, A5, B6, A8, B61, A61, B62, A62 - > +5v
While there are a number of +5v pins that will need intercepting to inject the 5v from a separate power supply, it's a LOT easier than if you also had to connect up twelve +3.3v lines too!
Digital card power supply notes (note some of this is stated in this Asylum post http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=35497):
U1 regulates 5v to 3.3v, with the first pin connected to ground, the second the output, and the third to the 5v bus. C1 & C3 are input filtering capacitors and C2 is the output filtering capacitor.
Also note these comments from a poster titled 'marcello' (from a post on this forum, sorry, I didn't dig it up to cite directly):
"Upgrading digital section:
Locate a good "audiophile"clock oscillator manufacturer. There are multiple offers available on the internet, varying from LC, Audiocom, etc. In NL, Audioart is making a VERY good clock but I'm not sure if they are selling it separately. If not I can intermediate.
I will come with my own clock this summer. 12V and the lowest noise and jitter you've heard of.
Two clocks are needed, one for 22.5792MHz and 1 for 24.576MHz. Replace the existing crystals (x1 and X2)with the corresponding clock oscillators. Power these external clock oscillators by a very good linear supply, or even a lead acid battery if the required voltage is 12Vdc.
Solder a 220uF/10V SG or SH OsCon capacitor from U6, AKM's 4114 chip AVDD pin 38 to ground. Best is to do this on the underside of the board, across BC25. Negative to the solder pad nearest to the "BC25" text.
Solder a 220uF/10V SG or SH OsCon capacitor across C8; positive to the pad towards text "C9", negative to pad towards text "C8".
These measures take care of the most basic limitations of the sound quality of the Juli@ card."
Analog card digital power supply notes:
U10 regulates +12v down to 5v for the digital chips on the analog card, with the same pinout as U1 above, G O I. C13 is the +12v input filter capacitor and C14 is the +5v output filtering capacitor.
Analog card analog power supply notes
U11 regulates +12v down to +9v, while U13 regulates -12v down to -9v. On U11, the tab is ground with the pin towards the of the card being the output and the pin towards the bottom the input. On U13, the tab is the -12v input with the pin towards the top of the card the output and the pin towards the bottom of the card the ground. C18 and C22 take care of input filtering for the +12v and -12v respectively, while C19 and C22 do the same for the +9v and -9v outputs.
Analog card analog circuitry notes
U22 and U23 are the output opamps, but I have to say given the size of those chips and the spacing between their pins, I'll never be replacing them. C70 and C73 are the output coupling caps, which I believe I could replace if I'm careful.
Separate Power Supply Voltage Insertion Points (note that this is inspired by and includes the information posted by Alfred in this post http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=49122 ):
DVCC1 - 5v into both digital and analog cards (Note that the 5v is only used in the digital card by regulator U1, which make the 3.3v used by all the chips on the digital card. If you are inserting 3.3v as below and are only using the digital card, you don't need to insert 5v). But be aware that the analog card uses both the 5v and the 3.3v, along with +12v & -12v.
P3V3D1 - 3.3v out of U1 regulator. Can be used as an insertion point for 3.3v to both the digital and analog cards by removing U1
DGND1 - Digital card ground
AGND1 & AGND2 - Analog card grounds. Use 1 if you are using the balanced outs, 2 if you are using the RCAs
P12V1 - +12v into the analog card
NVA1 - -12v into the analog card
P5VA1 - 5v out of regulator U10, which regulates down the +12v rail
PVA1 - +9v out of regulator U11, which regulates down the +12v rail
C19 - The side of this capacitor away from the center of the board is also the +9v out of regulator Ull
C23 - The side of this capacitor away from the center of the board is the -9v out of regulator U13
R29 (open pad on my Juli@) - the side of this set of resistor pads away from the 'R29' is an insertion point for the +12v
R32 (open pads on my Juli@) - the side of this set of resistor pads towards the center of the board is an insertion point for -12v
My hope is to take the Juli@ farther than described in previous posts... ultimately including powering it from a separate set of linear power supplies. Even though I have a separate DAC card coming, I believe that the Juli@ is capable of much better performance than what one gets with a stock card powered from the computer's busses.
Here's my roadmap...
Phase I - Improve PS filtering by replacing the input and output caps on the two digital and two analog regulators and adding local PS line reservoir caps.
Phase II - Improve analog signal transfer by replacing the output coupling caps.
Phase III - Clean up the power supply by cutting the links to the motherboard's power buses and feed the card with separate linear analog & digital supplies.
Phase IV - Further improve the power by replacing the on-board chip regulators with upgraded discrete regulators.
I've completed the first two phases (pictures above) and have it burning in. It is sounding quite improved from the stock card.
Greg in Mississippi
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