[pakultra]

U12 mod final update:
 
Hi my friends, I've just replaced the default TCXOs with 2 NDK NZ2520SD crystals thanks to Alex's advice. The new crystals have been running for only 10 hours but I am happy with the results already. So far, I can't say the improvement is like night and day, but there are clear differences if you know what to check for. Overall, the sound is more natural and more enjoyable with the NDKs. This is particularly evident with some of my favorite test passages of songs/music that are usually difficult to do right.  
 
Here are the NDKs that arrived in mail yesterday. They are so tiny I had to use my modded Microsoft Live Studio magnifier to see what's printed on them.
 

 
Here is how I put the NDKs into my U12:
 
1) Took out the TCXO's and soldered two Mill-Max 110-43-314-10-001000 gold dip14 (4 out) sockets in their place. These sockets have full 0.76µm gold contacts. The best available. These sockets will make rolling different crystals as easy as plug-and-play.
 

 

 
 
2) built pcb adapters for NDK crystals with Mill-Max 3320-0-00-15-00-00-03-0 gold pins: 
 
 


 
 
3) soldered Murata GRM2195C1H103FA01D smd 0.01 uf caps to the adapters. 

Capacitance	10000pF
Tolerance	±1%
Voltage - Rated	50V
Temperature Coefficient	C0G, NP0

 
These capacitors are ultra accurate, have No voltage drift, negligible temperature drift and do NOT age.
 

 
 
4) All soldering work was done with Wonder Solder (197 degree melting point) or Chip-Quik 137 degree low temperature solder paste. This prevented NDK' performance from being degraded by possible overheating during soldering process. The blue hookup wire used is Neotech UPOCC 20 AWG Cryo Treated mono-crystal pure copper wire. 
 

 
 
 

 
 
With NDKs added on top of my previous mods, I would consider my Gustard U12 modding project a full success and I am ready to move on.
 
Here is a full list of mods I've completed for my U12:
 
1) Grounded to IEC with Neotech UPOCC 20 AWG Cryo Treated 20 awg mono-crystal copper wire sourced from takefiveaudio.
 
2) Relay switch removed from board to stop possible power pollution of 80 mA current flowing through the board as well as to save 0.5w per hour power consumption;
 
3) Relay bypassed with the same Neotech UPOCC 20 awg cryo treated mono-crystal copper wire;
 
4) Onboard 5+ supplied to XMOS USB Vcc detection pin via a 470k pullup resistor to trick U12 into believing that it has seen USB power so that it will start communicating over USB; this mod is a must so that U12 does NOT use usb power anymore;
 
5) USB B socket's Vcc and Ground output pins de-soldered from board, flush-cut and insulated. This is a must so that U12 is completely and safely isolated from any USB power. It is safe to use regular USB cables with my modded U12, although data-only cable are recommended for best possible sound;
 
6) Coaxial transformer replaced with Murata DA101C sourced from digikey.ca;
 
7) Two 2200 uf capacitors replaced with ultralow impedance 2200 uf Nichicon HW UHW1E222MHD6 (14 mohm impedance) sourced from digikey.ca. These caps are better the Panasonic caps.
 
8) Took out TXCO's and soldered 14dip (4 out) gold sockets in its place;
 
9) NDKs fitted to handmade adapters and seated securely in the gold sockets;
 
 
I'd like to thank all forum members who have helped to make the mods possible. Special thanks go to hgpsemaj and Alex.
 
Thank you all!
 
Cheers!

 
 
pakultra
 
 
 




 

 

[ginetto61]

  Hi Gino, I have a regular old USB cable which goes from my PC to the MX-U8.
From the U8 I have a nice Digiflex AES cable that goes into my M51 which connects to my amp via the balanced out of the M51.
Again, I want to be clear I'm not trying to say that it is complete fact that the differences say between a well done USB and an AES can't be heard,
I'm just saying that I have yet to see any solid information presented as to why a USB out that is well designed should sound worse than say a AES out.

 
Sorry

... i lost my mind.  I did not remember that you have the Melodious ... but you have not updated your system 

Dac aside, your Nad must be really fantastic, i have also a pc, belden usb cable, Melodious, Canare AES DA202 and an Apogee dac and this is the best sound i heard in my home from a digital source
with an HP amp and k701.
The only thing that i would like to improve of the Melodious is the isolation from mains, but it is more an obsession of mine.
I think also the AES is a better connection than spdif.  For one thing is truly 110 ohm while RCA is not 75 ohm and this can cause problems. 
Thanks for the useful reply.  Kind regards,  gino 

 

[ginetto61]

  U12 mod final update:
 
Hi my friends, I've just replaced the default TCXOs with 2 NDK NZ2520SD crystals thanks to Alex's advice. The new crystals have been running for only 10 hours but I am happy with the results already. So far, I can't say the improvement is like night and day, but there are clear differences if you know what to check for. Overall, the sound is more natural and more enjoyable with the NDKs. This is particularly evident with some of my favorite test passages of songs/music that are usually difficult to do right.  
 
Here are the NDKs that arrived in mail yesterday. They are so tiny I had to use my modded Microsoft Live Studio magnifier to see what's printed on them.
 

 
Here is how I put the NDKs into my U12:
 
1) Took out the TCXO's and soldered two Mill-Max 110-43-314-10-001000 gold dip14 (4 out) sockets in their place. These sockets have full 0.76µm gold contacts. The best available. These sockets will make rolling different crystals as easy as plug-and-play.
 

 

 
 
2) built pcb adapters for NDK crystals with Mill-Max 3320-0-00-15-00-00-03-0 gold pins: 
 
 


 
 
3) soldered Murata GRM2195C1H103FA01D smd 0.01 uf caps to the adapters. 

Capacitance	10000pF
Tolerance	±1%
Voltage - Rated	50V
Temperature Coefficient	C0G, NP0

 
These capacitors are ultra accurate, have No voltage drift, negligible temperature drift and do NOT age.
 

 
 
4) All soldering work was done with Wonder Solder (197 degree melting point) or Chip-Quik 137 degree low temperature solder paste. This prevented NDK' performance from being degraded by possible overheating during soldering process. The blue hookup wire used is Neotech UPOCC 20 AWG Cryo Treated mono-crystal pure copper wire. 
 

 
 
 

 
 
With NDKs added on top of my previous mods, I would consider my Gustard U12 modding project a full success and I am ready to move on.
 
Here is a full list of mods I've completed for my U12:
 
1) Grounded to IEC with Neotech UPOCC 20 AWG Cryo Treated 20 awg mono-crystal copper wire sourced from takefiveaudio.
 
2) Relay switch removed from board to stop possible power pollution of 80 mA current flowing through the board as well as to save 0.5w per hour power consumption;
 
3) Relay bypassed with the same Neotech UPOCC 20 awg cryo treated mono-crystal copper wire;
 
4) Onboard 5+ supplied to XMOS USB Vcc detection pin via a 470k pullup resistor to trick U12 into believing that it has seen USB power so that it will start communicating over USB; this mod is a must so that U12 does NOT use usb power anymore;
 
5) USB B socket's Vcc and Ground output pins de-soldered from board, flush-cut and insulated. This is a must so that U12 is completely and safely isolated from any USB power. It is safe to use regular USB cables with my modded U12, although data-only cable are recommended for best possible sound;
 
6) Coaxial transformer replaced with Murata DA101C sourced from digikey.ca;
 
7) Two 2200 uf capacitors replaced with ultralow impedance 2200 uf Nichicon HW UHW1E222MHD6 (14 mohm impedance) sourced from digikey.ca. These caps are better the Panasonic caps.
 
8) Took out TXCO's and soldered 14dip (4 out) gold sockets in its place;
 
9) NDKs fitted to handmade adapters and seated securely in the gold sockets;
 
 
I'd like to thank all forum members who have helped to make the mods possible. Special thanks go to hgpsemaj and Alex.
 
Thank you all!
 
Cheers!

 
 
pakultra
 
 
 




 

 
Hi and sincere congratulations for your impressive project. Really,
Sorry if you already told me and i forgot it (it was you using the Blue Circle mains filter?)  
but are you using some kind of mains filter device ?  i ask this because i am sure than an Achille's heel of the U12 is poor mains noise filtering. 
Mains noise entering a digital device is one of the worst evils for sound.
I have bought and not yet received a simple mains filter to listen for any improvements.
I am sure that with the U12 in a normal home context some mains filtering solution is mandatory for the best result.
Thanks and congratulations again,   gino   

 

[Sonic Defender]

   
Sorry

... i lost my mind.  I did not remember that you have the Melodious ... but you have not updated your system 

Dac aside, your Nad must be really fantastic, i have also a pc, belden usb cable, Melodious, Canare AES DA202 and an Apogee dac and this is the best sound i heard in my home from a digital source
with an HP amp and k701.
The only thing that i would like to improve of the Melodious is the isolation from mains, but it is more an obsession of mine.
I think also the AES is a better connection than spdif.  For one thing is truly 110 ohm while RCA is not 75 ohm and this can cause problems. 
Thanks for the useful reply.  Kind regards,  gino 

Hi Gino, thank you, and yes the NAD M3 is a very nice integrated amplifier. I will update my signature, thanks for reminding me! Cheers.

 

[riffer]

  U12 mod final update:
 
.....  




 

 
Nicely done.

 

[pakultra]

 
Sorry if you already told me and i forgot it (it was you using the Blue Circle mains filter?)  
but are you using some kind of mains filter device ?  i ask this because i am sure than an Achille's heel of the U12 is poor mains noise filtering. 
Mains noise entering a digital device is one of the worst evils for sound.
I have bought and not yet received a simple mains filter to listen for any improvements.
I am sure that with the U12 in a normal home context some mains filtering solution is mandatory for the best result.
Thanks and congratulations again,   gino   

 
Thank you ginetto61
 
Yes, I am the one using the Blue Circle Audio mains filter. It cost me about $300. I guess it is just some inductors and well chosen capacitors inside. These are normally good for killing differential mode noises. I am using ferrite beads to tame common mode noises. However, I didn't notice any difference with or without the ferrite beads. Beside these, I don't have any other mains filter device. I don't know exactly which mains filter device you have in mind (pictures?), but your comments just inspired me to use the Murata Hybrid Chokes that I have on my board to curb the common mode noises

These chokes cost about 4 dollar each. They are rated for 300v, so there won't be any problems connecting them to the mains. I have two at hand. I can use one for U12 and one for my DAC. But I have to desolder them from the PCB first.
 
Cheers

 
pakultra

 

[pakultra]

 

  U12 mod final update:
 
.....  




 

 
Nicely done.

Thank you bro

 

[ginetto61]

Thank you ginetto61
Yes, I am the one using the Blue Circle Audio mains filter. It cost me about $300. I guess it is just some inductors and well chosen capacitors inside. These are normally good for killing differential mode noises.
I am using ferrite beads to tame common mode noises. However, I didn't notice any difference with or without the ferrite beads. Beside these, I don't have any other mains filter device.

 
Hi and thanks again for the helpful advice.
I guess you have also tried with the Blue Circle Audio filter. With very clean mains maybe there will be no big differences, but this is hardly the case in a normal context.
I see many dacs with toroidal transformer using a mains filter before the transformer.  I still prefer EI, maybe shielded,  but these days toroidals are everywhere, they are very very popular.
 
 

I don't know exactly which mains filter device you have in mind (pictures?),

 
just something basic like this one ... it should be better than nothing .. i will put it before the converter mains socket.
 
http://www.tme.eu/html/gfx/ramka_3256.jpg
 
I saw also used for low power consumption devices, after the transformers, diodes of the Schottky type
 

http://en.wikipedia.org/wiki/Schottky_diode
 
The most important difference between the p–n and Schottky diode is reverse recovery time (Trr), when the diode switches from conducting to non-conducting state. Where in a p–n diode the reverse recovery time can be in the order of hundreds of nanoseconds and less than 100 ns for fast diodes, Schottky diodes do not have a recovery time, as there is nothing to recover from (i.e. no charge carrier depletion region at the junction).
The switching time is ~100 ps for the small signal diodes, and up to tens of nanoseconds for special high-capacity power diodes.
With p–n-junction switching, there is also a reverse recovery current, which in high-power semiconductors brings increased EMI noise.
With Schottky diodes, switching is essentially instant with only slight capacitive loading, which is much less of a concern. 

 

but your comments just inspired me to use the Murata Hybrid Chokes that I have on my board to curb the common mode noises

These chokes cost about 4 dollar each. They are rated for 300v, so there won't be any problems connecting them to the mains. I have two at hand.
I can use one for U12 and one for my DAC. But I have to desolder them from the PCB first.
Cheers

 
pakultra

 
these are very interesting.   I will look for a data sheet with some application notes.
Given that the BC Audio filter is already very effective maybe in your case the added benefits will be marginal.
Instead i have nothing for now and i strongly feel i have to put something.
These are very very interesting.  And also very compact.
I should receive the above filter very soon.  I am curious to listen to the converters (i have both) with this filter in line.
Actually i do not know how good is really the Gustard U12 as stock.  It seems well done.
As your great project shows some more attention to details, that details are not, can be very rewarding in terms of performance.
Thanks a lot again,   gino

 

[abartels]

  U12 mod final update:
 
Hi my friends, I've just replaced the default TCXOs with 2 NDK NZ2520SD crystals thanks to Alex's advice. The new crystals have been running for only 10 hours but I am happy with the results already. So far, I can't say the improvement is like night and day, but there are clear differences if you know what to check for. Overall, the sound is more natural and more enjoyable with the NDKs. This is particularly evident with some of my favorite test passages of songs/music that are usually difficult to do right.  
 
Here are the NDKs that arrived in mail yesterday. They are so tiny I had to use my modded Microsoft Live Studio magnifier to see what's printed on them.
 

 
Here is how I put the NDKs into my U12:
 
1) Took out the TCXO's and soldered two Mill-Max 110-43-314-10-001000 gold dip14 (4 out) sockets in their place. These sockets have full 0.76µm gold contacts. The best available. These sockets will make rolling different crystals as easy as plug-and-play.
 

 

 
 
2) built pcb adapters for NDK crystals with Mill-Max 3320-0-00-15-00-00-03-0 gold pins: 
 
 


 
 
3) soldered Murata GRM2195C1H103FA01D smd 0.01 uf caps to the adapters. 

Capacitance	10000pF
Tolerance	±1%
Voltage - Rated	50V
Temperature Coefficient	C0G, NP0

 
These capacitors are ultra accurate, have No voltage drift, negligible temperature drift and do NOT age.
 

 
 
4) All soldering work was done with Wonder Solder (197 degree melting point) or Chip-Quik 137 degree low temperature solder paste. This prevented NDK' performance from being degraded by possible overheating during soldering process. The blue hookup wire used is Neotech UPOCC 20 AWG Cryo Treated mono-crystal pure copper wire. 
 

 
 
 

 
 
With NDKs added on top of my previous mods, I would consider my Gustard U12 modding project a full success and I am ready to move on.
 
Here is a full list of mods I've completed for my U12:
 
1) Grounded to IEC with Neotech UPOCC 20 AWG Cryo Treated 20 awg mono-crystal copper wire sourced from takefiveaudio.
 
2) Relay switch removed from board to stop possible power pollution of 80 mA current flowing through the board as well as to save 0.5w per hour power consumption;
 
3) Relay bypassed with the same Neotech UPOCC 20 awg cryo treated mono-crystal copper wire;
 
4) Onboard 5+ supplied to XMOS USB Vcc detection pin via a 470k pullup resistor to trick U12 into believing that it has seen USB power so that it will start communicating over USB; this mod is a must so that U12 does NOT use usb power anymore;
 
5) USB B socket's Vcc and Ground output pins de-soldered from board, flush-cut and insulated. This is a must so that U12 is completely and safely isolated from any USB power. It is safe to use regular USB cables with my modded U12, although data-only cable are recommended for best possible sound;
 
6) Coaxial transformer replaced with Murata DA101C sourced from digikey.ca;
 
7) Two 2200 uf capacitors replaced with ultralow impedance 2200 uf Nichicon HW UHW1E222MHD6 (14 mohm impedance) sourced from digikey.ca. These caps are better the Panasonic caps.
 
8) Took out TXCO's and soldered 14dip (4 out) gold sockets in its place;
 
9) NDKs fitted to handmade adapters and seated securely in the gold sockets;
 
 
I'd like to thank all forum members who have helped to make the mods possible. Special thanks go to hgpsemaj and Alex.
 
Thank you all!
 
Cheers!

 
 
pakultra
 
 
 




 

 
Nice Job pakultra, looking good!
 
Just wait another 100 hours or so before making a final listening impression 

It will gain much much more 

 
Well done,
 
Cheers 

 
Alex

 

[pakultra]

 

 
Hi ginetto61,
 
I like your idea of adding a mains filter like the type you showed us. I've done some searching and I am planning to order these based on their superior filtering specs:
 

Manufacturer	Schaffner EMC Inc
Manufacturer Part Number	FN2090-4-06
Description	FILTER MULTI-STAGE HI PERFORM 4A

 

 

Manufacturer	Schaffner EMC Inc
Manufacturer Part Number	FN2090-12-06
Description	FILTER MULTI-STAGE HI PERF 12A

 

 
These filters have two stages and look quite promising based on their datasheets.
 
Besides, I will test these in my power supply to see if they can actually improve things. These will cover almost all frequencies up to 5.5 GHZ
 

2			490-5055-ND	FILTER EMI 15A 25V 100KHZ-1GHZ		1 Immediate	0	5.52000	$5.52
3			445-2991-1-ND	FILTER 3-TERM .65 TO 2.5GHZ SMD		3 Immediate	0	0.82000	$2.46
4			445-2989-1-ND	FILTER 3-TERM 2.0 TO 5.5GHZ SMD		3 Immediate	0	0.73000	$2.19

 
I also believe that diodes are important. I've got 8 Cree diodes at hand that I ordered last week. These diodes are believed to be far superior to even the best Schottky diodes because they have zero recovery voltage or current spikes.
 

Manufacturer	Cree Inc
Manufacturer Part Number	C3D02060E
Description	DIODE SCHOTTKY 600V 2A TO252-2

I will most probably not be able to notice any improvement even if I do put these diodes into my ultra-quite power supply. I don't know. but it's fun to explore and learn...
 
Cheers

 
pakultra

 

[hgpsemaj]

  U12 mod final update:
 
Hi my friends, I've just replaced the default TCXOs with 2 NDK NZ2520SD crystals thanks to Alex's advice. The new crystals have been running for only 10 hours but I am happy with the results already. So far, I can't say the improvement is like night and day, but there are clear differences if you know what to check for. Overall, the sound is more natural and more enjoyable with the NDKs. This is particularly evident with some of my favorite test passages of songs/music that are usually difficult to do right.  
 
Here are the NDKs that arrived in mail yesterday. They are so tiny I had to use my modded Microsoft Live Studio magnifier to see what's printed on them.
 
Here is how I put the NDKs into my U12:
 
1) Took out the TCXO's and soldered two Mill-Max 110-43-314-10-001000 gold dip14 (4 out) sockets in their place. These sockets have full 0.76µm gold contacts. The best available. These sockets will make rolling different crystals as easy as plug-and-play.
 
2) built pcb adapters for NDK crystals with Mill-Max 3320-0-00-15-00-00-03-0 gold pins: 
 
3) soldered Murata GRM2195C1H103FA01D smd 0.01 uf caps to the adapters. 

Capacitance	10000pF
Tolerance	±1%
Voltage - Rated	50V
Temperature Coefficient	C0G, NP0

 
These capacitors are ultra accurate, have No voltage drift, negligible temperature drift and do NOT age.
 
4) All soldering work was done with Wonder Solder (197 degree melting point) or Chip-Quik 137 degree low temperature solder paste. This prevented NDK' performance from being degraded by possible overheating during soldering process. The blue hookup wire used is Neotech UPOCC 20 AWG Cryo Treated mono-crystal pure copper wire. 
 
With NDKs added on top of my previous mods, I would consider my Gustard U12 modding project a full success and I am ready to move on.
 
Here is a full list of mods I've completed for my U12:
 
1) Grounded to IEC with Neotech UPOCC 20 AWG Cryo Treated 20 awg mono-crystal copper wire sourced from takefiveaudio.
 
2) Relay switch removed from board to stop possible power pollution of 80 mA current flowing through the board as well as to save 0.5w per hour power consumption;
 
3) Relay bypassed with the same Neotech UPOCC 20 awg cryo treated mono-crystal copper wire;
 
4) Onboard 5+ supplied to XMOS USB Vcc detection pin via a 470k pullup resistor to trick U12 into believing that it has seen USB power so that it will start communicating over USB; this mod is a must so that U12 does NOT use usb power anymore;
 
5) USB B socket's Vcc and Ground output pins de-soldered from board, flush-cut and insulated. This is a must so that U12 is completely and safely isolated from any USB power. It is safe to use regular USB cables with my modded U12, although data-only cable are recommended for best possible sound;
 
6) Coaxial transformer replaced with Murata DA101C sourced from digikey.ca;
 
7) Two 2200 uf capacitors replaced with ultralow impedance 2200 uf Nichicon HW UHW1E222MHD6 (14 mohm impedance) sourced from digikey.ca. These caps are better the Panasonic caps.
 
8) Took out TXCO's and soldered 14dip (4 out) gold sockets in its place;
 
9) NDKs fitted to handmade adapters and seated securely in the gold sockets;
 
 
I'd like to thank all forum members who have helped to make the mods possible. Special thanks go to hgpsemaj and Alex.
 
Thank you all!
 
Cheers!

 
 
pakultra
 
 
 




 

 
 
Hello Pakultra,
 
A job that is well done is like a benchmark.
 
 
 
Cheers,    

 
hgpsemaj 

 

[Voltot]

pakultra thanks. I modded my U12 same as you but without 470k pullup resistor. Does it matter?

 

[ginetto61]

   
Hi ginetto61,
 
I like your idea of adding a mains filter like the type you showed us. I've done some searching and I am planning to order these based on their superior filtering specs:
 

Manufacturer	Schaffner EMC Inc
Manufacturer Part Number	FN2090-4-06
Description	FILTER MULTI-STAGE HI PERFORM 4A

 

 

Manufacturer	Schaffner EMC Inc
Manufacturer Part Number	FN2090-12-06
Description	FILTER MULTI-STAGE HI PERF 12A

 

 
These filters have two stages and look quite promising based on their datasheets.
 
Besides, I will test these in my power supply to see if they can actually improve things. These will cover almost all frequencies up to 5.5 GHZ
 

2			490-5055-ND	FILTER EMI 15A 25V 100KHZ-1GHZ		1 Immediate	0	5.52000	$5.52
3			445-2991-1-ND	FILTER 3-TERM .65 TO 2.5GHZ SMD		3 Immediate	0	0.82000	$2.46
4			445-2989-1-ND	FILTER 3-TERM 2.0 TO 5.5GHZ SMD		3 Immediate	0	0.73000	$2.19

 
I also believe that diodes are important. I've got 8 Cree diodes at hand that I ordered last week. These diodes are believed to be far superior to even the best Schottky diodes because they have zero recovery voltage or current spikes.
 

Manufacturer	Cree Inc
Manufacturer Part Number	C3D02060E
Description	DIODE SCHOTTKY 600V 2A TO252-2

I will most probably not be able to notice any improvement even if I do put these diodes into my ultra-quite power supply. I don't know. but it's fun to explore and learn...
 
Cheers

 
pakultra

 
Hi Pakultra and thanks for the very interesting advice.
Clearly i am not really serious in my approach for different reasons.  Just to start i have no scope to see what is going on in a circuit.
I am just peeping inside famous units of great sound hoping to learn something.   A schematic would be much helpful for this.
The parts you have selected i guess are the best available.  As you say it is difficult to foresee if they will have any impact on sound.
Maybe it is trivial but for a me a great unit starts with a great power supply.
And in low signal units suppression of all kind of noise (mains noise, diodes noise, EMI/RFI noise) is fundamental.
But again your approach to kill the noise after the transformer is equally good.
A scope more than a ear could show the situation.   A scope is much more sensitive than a human ear.
Where will you buy these parts from ?  i like the Shaffner filters very much.  I could skip on the transformer replacement and try one of these filters.
Maybe the outcome would be even better ?
Just as a reference this is a very good dac from Schiit Audio ... actually their new TOTL dac said to have an exceptional sound.
 
http://schiit.com/public/upload/general/imagecache_thumbnail_product_gallery_large/yggdrasil_pcb_1000.jpg
 
Looking at its power supply can give important hints about how a PS for digital euipment must be designed.
A very strong chain clerly cannot have weak links. If all the dac is extremely good the PS must also be very good indeed.
Anyway also dealing with the PS noise at regulators level could work perfectly the same (actually even better ... maybe i am overrating this PS issue).
So my idea is that the same parts (with the right ratings of course) put in a cheaper unit could give some benefits.
For the best units that provide the best sound possible the parts selected can be the best available. Cost is less of a constraint and top sound is the goal.
You see ? no toroidals ... attention to mains filtering and rectifying diodes ... chokes ...
Do you have some pics of your modified U12 ?  how are you placing the new PS ?
I would think to a new box for sure.   Something bigger with the space for everything inside. The U12 box is already quite full of parts.
Thanks again,  gino

 

[pakultra]

  pakultra thanks. I modded my U12 same as you but without 470k pullup resistor. Does it matter?

Hi Voltot,
 
You are most welcome.
 
No, the pullup resistor doesn't matter much. U12 will work fine without it.
 
The purpose of the resistor is to minimize voltage/current fight/conflict if a USB Vcc is accidentally connected and introduced into U12. The resistor serves as a safeguard to protect both U12 and your computer's USB port while minimizing current flow through the jumper. But it is not necessary if you have already hard-disconnected the Vcc pin of your U12.
 
Congratulations on your mods!
 
Cheers

 
pakultra

 

[pakultra]

Hi ginetto61,
 
I am buying the filters from Digikey.ca.
 
Here:
http://www.digikey.ca/scripts/DkSearch/dksus.dll?Detail&itemSeq=173055166&uq=635684855024229284
http://www.digikey.ca/scripts/DkSearch/dksus.dll?Detail&itemSeq=173130440&uq=635684855024229284
 
The 4A model is sold cheaper here: https://www.e-sonic.com/product-detail/schaffner-emc/fn2090406.html?p=12331583
 
Ideally, I'd like to put one of these before each audio device and each EMI source as well (for example my PC and my TV). I will also need to add a metal box for each filter. I am considering sth. like this:
 

 
http://vk3kid.org/?page_id=1725
 
All this means a lot of work and money. I will do it step by step if initial results are good.
 
Thanks for sharing the Schiit Audio device. I love seeing beautiful layout like that...
 
The LT3042 has strong filtering power for RFI noises below 1MHZ, but it doesn't do anything to higher frequency RFI noises, so additional filtering either before or after is needed if RFI is a problem.
 
There is no room inside U12 for any major power supply mods. I haven't done anything to the U12 main power supply yet because that would require drilling a hole on its beautiful case to let the external power go in. Besides, I've only made one good PSU, which has already been committed to my DAC.
 
Here is how my U12 looks like with its top off:

 
 
 
Of course I've put the top cover back on after taking the photo. It looks exactly the same as a new unmodded U12 from outside.
 
Cheers

 
 
pakultra