Paradisea DAC Mod

tanchiro58 · « **Reply #20 on:** 30 Apr 2007, 02:41 am »

Quote

I'm looking at a digram of the SC947-02, just to be clear, pins 1 & 4 are on the primary/input side of the SC947-02, and pins 5,6,7 & 8 are on the secondary/output side.

Hello Everyone,

Based on Mauimods (Anthony) and jhm731 I have experimented this way to mod my MHDT Renaissance II (or Paradisea) DAC by installing the SC947-02 pulse transformer three days ago and still in the progress of break-in.
1. You can install the tranny anywhere in the DAC but stay away from the PCB circuit board to avoid RFI/EMI
2. Find the resistor 75Ohm which is between RCA and BNC connectors (make sure to check if it s 75Ohm with your multimeter).
3. It is up to you if you can install aa extra RCA or BNC connectors besides the one you have on your DAC. Since I do not want to cut the trace betwenn the two connectors I did mount another RCA one for best result.
4. At the Sc947-02 primary pin 1(red dot) go to one end of resistor 75Ohm where BNC and RCA center pins met. Pin 4 go to ground at the other end of resistor 75Ohm.
5. At a secondary pin 8 will go to center pin (positive) of your mounted RCA or BNC, pin 5 goes to negative of connector. Pins 6 and 7 (shielded) connected together and go to ground plane via a 10nF ceramic cap according to Brian T (I use Rifa 0.01uF/250V secure cap).

Like I said I connected the DAC to my non-modded (NO pulse tranny) SB3. The sound to me is very detailed and defined mid, high and bottom with 3D soundstage. It is also very involved.

viperrabbit · « **Reply #21 on:** 30 Apr 2007, 03:40 am »

Hi Tan

Quote

3. It is up to you if you can install extra RCA or BNC connectors besides the one you have on your DAC. Since I do not to cut the trace betwenn the two connectors I did mount another RCA one for best result.

Why is it necessary to install extra connector? Why the need to cut the trace between the two connectors? What is "trace"?

Quote

5. At a secondary pin 8 will go to center pin (positive) of your mounted RCA or BNC, pin 5 goes to negative of connector. Pins 6 and 7 (shielded) connected together and go to ground plane via a 10nF ceramic cap according to Brian T (I use Rifa 0.01uF/250V secure cap).

If not using extra connector, where should pin 5, 6 & 7 be connected to? Where is the 10nF ceramic cap mounted?

Thanks.

tanchiro58 · « **Reply #22 on:** 30 Apr 2007, 04:31 am »

Viperrabbit,

Extra connector is only for using with SC947-02 DIRECTLY. The TRACE is a connection between BNC and RCA in your DAC which is purposed by MHDT for convenient use of either one connector originally. When F100 posted the modded DAC pics jhm731 had suggested to cut the trace for serial connection with pulse transformer (SC947-02). Based on jhm731 suggestion if you do not cut the trace you are automatically connected in parallel with both connectors. You also will degrade the sound I think.

This is only my experiment. I am modifying based on Jon Paul research and jhm731 or Mauimods suggestion (different than F100). If you are not using an extra connector like I did then you will have to cut the trace to let the tranny fully perform its function. I do not want to destroy (by cutting the trace) the original PCB of the DAC and found the better way to use the extra connector. I have tested both versions and like this version the most. My music is very natural and involved.

Builder Brad · « **Reply #23 on:** 8 May 2007, 07:29 pm »

SC947-02 signal tranformers arrived in the post less that 1 week to the UK! we sometimes wait longer for local mail!

Cheers Josh

hopefully I have managed to get the correct image to display above, otherwise I am in trouble aa

I do not normally take my time, even with the more involved mods - so this is totally out of character - I have even taken the time to take a picture and edit it!

looking at the paradisea pcb and the SC947-02 transformer there seems like an ideal position to mount this component between the output pins and the connection for the 75 ohm resistor, which keeps the traces very short and allows me to solder directly from pin 4 to the 75 ohm resistor and pin 1 signal - clearly this will only work with the traces cut as shown.

On the output side I will be able to solder directly onto, or with a very short link, the earth pad for the 75 ohm resistor and also use this earth point for the shild pins, if required (6,7). Pin 8 can then be linked to the RCA input as shown. I am not planning on using the BNC connector and this will now be redundant.

any thoughts?

is the polarity important ie pin 1 earth/signal pin 4 signal/earth?

Brad

Builder Brad · « **Reply #24 on:** 8 May 2007, 07:32 pm »

Builder Brad · « **Reply #25 on:** 8 May 2007, 07:37 pm »

here we go - hopefully this will work. I could have broken the DAC several times over in the time it has taken to work this out

Builder Brad · « **Reply #26 on:** 8 May 2007, 07:39 pm »

this is how I planned to position the transformer

Builder Brad · « **Reply #27 on:** 8 May 2007, 07:42 pm »

now I`m on a roll....

there is room to do this, obviously I will have to make sure that nothing gets shorted, and i will probably need to remodel the pcb a little.

Builder Brad · « **Reply #28 on:** 8 May 2007, 07:45 pm »

just looking at the pin numbers above, I can now see that they are the wrong way arounf PIN 1 is the to RSH pin with 5PIN 5 on the bottom LHS, but the general principal is the sam. My earlier question regarding the polarity is now much more relevant.

Brad

jhm731 · « **Reply #29 on:** 8 May 2007, 11:09 pm »

Quote from: Builder Brad on 8 May 2007, 07:45 pm

just looking at the pin numbers above, I can now see that they are the wrong way arounf PIN 1 is the to RSH pin with 5PIN 5 on the bottom LHS, but the general principal is the sam. My earlier question regarding the polarity is now much more relevant.

Brad

Polarity is not important.

Builder Brad · « **Reply #30 on:** 9 May 2007, 05:36 pm »

just 2 be sure I can connect the primary (pins 1&4)either way round from signal to ground effectively across the 75 ohm resistor.

tanchiro58 · « **Reply #31 on:** 9 May 2007, 06:39 pm »

Quote from: Builder Brad on 9 May 2007, 05:36 pm

just 2 be sure I can connect the primary (pins 1&4)either way round from signal to ground effectively across the 75 ohm resistor.

Builder Brad,

Pin 1 to the meeting point of two digital connectors (stock BNC & RCA) and 75 Ohm resistor.
Pin 4 to the other leg of 75Ohm resistor which is located near the edge of PCB.

Tan

Builder Brad · « **Reply #32 on:** 9 May 2007, 07:02 pm »

cheers Tan

one last Q. does the pin numbering on this transformer follow the normal IC convention ie. clockwise from the marked no 1 pin with 1+5 on opposite corners?

Brad

tanchiro58 · « **Reply #33 on:** 9 May 2007, 07:43 pm »

Quote from: Builder Brad on 9 May 2007, 07:02 pm

cheers Tan

one last Q. does the pin numbering on this transformer follow the normal IC convention ie. clockwise from the marked no 1 pin with 1+5 on opposite corners?

Brad

Brad,

I am not sure about this since I am not a theoritical guy. What I mean I just hand on to practice and to learn from other's and my experiences until I get a good results. Also my experiments have proved that I have done the mods for SB3 and my MHDT DAC so many times to test which way I like the most for my taste. Like I just done to replace the stock 75 Ohm metal resistor with an Allen Bradly 115Ohm carbon resistor.

You just follow the shematic of SC947-02 on Jon Paul papers then you will be okay. It is up to your taste. That is why I do not like to spend money for someone who mods my stuffs (kind of wasting money). F100 does not like the sound when he mods his Paradisea DAC and SB3 based on Jon Paul Research. Therefore, he just keeps the way he is done modifying his SB3 but not his DAC. To me I like the most to mod both.

We use pins 1 & 4 on the primary and pins 8 & 5 on the secondary. Pins 6 & 7 are shielded and also very important part of the pulse transformer. I do not quite understand your question about clockwise from the marked pin 1 with 1+5 on opposite corner?

Tan

jhm731 · « **Reply #34 on:** 9 May 2007, 07:51 pm »

Quote from: Builder Brad on 9 May 2007, 07:02 pm

cheers Tan

one last Q. does the pin numbering on this transformer follow the normal IC convention ie. clockwise from the marked no 1 pin with 1+5 on opposite corners?

Brad

SC947-02 transformer Pin out:

1 8
2 7-shield
3 6-shield
4* 5

* marked

As I posted in the SC947-02 group buy thread, per Mr.Paul, the shields should face the driving or driven IC.

That means you want pins 5 & 8 connected to the 75Ohm resistor which is in front of the DAC's input receiver IC.

tanchiro58 · « **Reply #35 on:** 9 May 2007, 08:52 pm »

Quote

That means you want pins 5 & 8 connected to the 75Ohm resistor which is in front of the DAC's input receiver IC.

jhm731,

Based on Jon Paul research in pic 35 on page 30 if you use 2:1 pulse transformer you will install 2:1 to Tx and 1:2 to Rx. Would 1:1 pulse transformer be connected same as 2:1 one? I install SC947-02 in my DAC with pins 1&4 to 75Ohm and pins 5&8 to RCA connector. So you do reversely.

Tan

jhm731 · « **Reply #36 on:** 9 May 2007, 09:46 pm »

Quote from: tanchiro58 on 9 May 2007, 08:52 pm

Quote
That means you want pins 5 & 8 connected to the 75Ohm resistor which is in front of the DAC's input receiver IC.

jhm731,

Based on Jon Paul research in pic 35 on page 30 if you use 2:1 pulse transformer you will install 2:1 to Tx and 1:2 to Rx. Would 1:1 pulse transformer be connected same as 2:1 one? I install SC947-02 in my DAC with pins 1&4 to 75Ohm and pins 5&8 to RCA connector. So you do reversely.

Tan

Tan

Mr.Paul told me the shields should face the driving or driven IC.

So yes, try reversing the connections in your DAC.

tanchiro58 · « **Reply #37 on:** 9 May 2007, 09:52 pm »

jhm731,

Ok but where are the shields connecting to? Right now I connected the shields to ground plane via a .01 uF/250V ceramic secure cap. Is there a big improvement when reversing? Thanks.

Tan

jhm731 · « **Reply #38 on:** 10 May 2007, 12:46 am »

Quote from: tanchiro58 on 9 May 2007, 09:52 pm

jhm731,

Ok but where are the shields connecting to? Right now I connected the shields to ground plane via a .01 uF/250V ceramic secure cap. Is there a big improvement when reversing? Thanks.

Tan

Tan-

I haven't heard the Paradisea DAC, but I doubt it's ground plane is as noisy as the SB3's, so the .01 uF cap connection maybe just fine, or you could try running a ground wire back the IEC jack.

Don't know if reversing the connections will make a "big improvement," but I'm sure it won't degrade the performance you're getting.

GBB · « **Reply #39 on:** 10 May 2007, 04:46 am »

Quote from: jhm731 on 9 May 2007, 09:46 pm

Mr.Paul told me the shields should face the driving or driven IC.

Just to clarify this comment, in their FAQ http://www.scientificonversion.com/faq.html, Scientific Conversions
highlights Fig 40 of their AES 2003 paper as a good reference for reducing EMI emission and susceptibility. It shows the shield side of the transformer going towards the DAC receiver chip.

So I believe you are suggesting that on the SB3 side of the system, the secondary of the transformer should be driven and the primary should go to the SPDIF output jack. And on the DAC receiver side, the primary should go to the SPDIF jack and the secondary should go to the DAC receiver as shown in the Figure.

Is that right?

Thanks,
---Gary