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樓主: Kiko

MHZS - Mystery of the DAC Chip

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alfcat 發表於 2007-11-7 09:10:16 | 顯示全部樓層
Dear t.,

So I need a separate PSU to supply power to this unit and connect the power output to the connectors on the top.

For the lower LEFT connectors, where should I connect the L.R and the Gnd to? Any idea which point on the CD 33 PCB?

I can get hold of the board but I need to know where should I connect the wires to the PCB. Please advise. Many thanks.

CAT
leo 發表於 2007-11-8 00:52:33 | 顯示全部樓層
[quote:ed5529b577="alfcat"]Dear t.,

So I need a separate PSU to supply power to this unit and connect the power output to the connectors on the top.

For the lower LEFT connectors, where should I connect the L.R and the Gnd to? Any idea which point on the CD 33 PCB?

I can get hold of the board but I need to know where should I connect the wires to the PCB. Please advise. Many thanks.

CAT[/quote]

I will need to find a good clear picture of your Cd33 so I need to have a search through the posts,  we need to be 100% you understand before fitting :wink:
Also as I do not know the Lite dac circuit we need a clear picture showing the layout.

There is several different ways to implement that dac board, you will need to compare them to see which you like best,  we will go the easy way as I think the I2S input for the digital section may be a little hard for me to explain how to do it,  I only recommend and help to do mods if I feel you are 100% confident in doing it
SPDIF will NOT be as good as the I2S  but is easier
leo 發表於 2007-11-8 01:26:58 | 顯示全部樓層
We need schematic for this http://eshop.diyclub.biz/product_info.php?cPath=23_135&products_id=266
The one posted there is too small

We need to find a suitable output signal from that Lite dac,  lift ONE side of the 0.33uf coupling capacitors inside the CD33 (side nearest the CD33 op-amps) and run the left signal to one of those lifted 0.33uf capacitors and the Right signal to the other lifted 0.33uf  capacitor, this will then bypass the CD33's internal dac and op-amps.
With the Lite dac you should be able use the Left and Right signals from before the Lite dacs op-amps or after the op-amps,  both ways will work and both ways will sound a lot different

A schematic makes things much easier to explain :?
Koifarm 發表於 2007-11-8 05:52:00 | 顯示全部樓層
Yesterday i tryed the diygene board in a MHZS 66. It was very disapointed.

I aspected to get the noise level down with the tube stage still in use. But it was not possible. Here a some of my observations:

DIYgene dac with a seperate powersupply  and output direct ( no tube stage attached ) = No noise but sound was scharp like real digital sound.

DIYGene dac with MHZS powersupply and output direct = Strange noises from drive in the sound.

DIYgene dac with tubestage attached = scharp sound and same noise as before mod.

So this was not satisfactory for me.

DIYgene dac is best when standalone. If any one likes to try make me a offer for the DAC.

I think to only option to get lost of the noise is to redesign the power supply of the DAC section with separate supply for analog and digital part.

I must tell i like the sound of my MHZS 33. I compared him with my new Shanling CD-T100 SE i have got yesterday. Blues played on my MHZS player like i am in a pub.
alfcat 發表於 2007-11-8 09:43:26 | 顯示全部樓層
Dear Koifarm,

Thanks for your information. I am just about the get the LITE DAC-AH board. Now, I have to give it a second thought.

KK Ho once said to further modify the CD 33, it is best to have separate power supply for different sections.

Can you share some information on HOW this can be done.

CAT
leo 發表於 2007-11-8 11:06:55 | 顯示全部樓層
Koifarm, did you run the TDA1543 signal output from the I/V resistors to the MHZS 0.33uf  caps?
If you run the signal from the diygenie op-amps output to the MHSZ it may be overloading the tubes  (too high signal)

The strange noises you heard using the MHZS psu may be oscillation caused by instability
leo 發表於 2007-11-8 11:25:23 | 顯示全部樓層
If I was to try a separate dac this is how I'd connect it

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Koifarm 發表於 2007-11-9 03:16:22 | 顯示全部樓層
Yes, i did connect the signal from the I/V resistor to the capacitors as you draw on your photo. The noise i heard was the same as in the original player. Hi static from the digitalpart of the board( display driver and sampler ). They share the powersupply with the analog part of the DAC. The noise comes through the grounding shield. If i use a osciliscoop the grounding has a lot of static noise.
leo 發表於 2007-11-9 18:26:06 | 顯示全部樓層
Other problem with these cdp's is that the I2S lines are run from long unshielded wires.
The dac chip and clock circuit in mine is now run from a small transformers and discrete regulators.
I may use mini shielded co-ax for the digital i2S lines feeding the dac, the chip is too far away being on a separate board
alfcat 發表於 2007-11-9 23:22:40 | 顯示全部樓層
Dear t.,

I just got my LITE DAC-AH today. It is really late now here in Hong Kong, close to 11:15pm and I don't have the time to unscrew everything to reveal the DAC yet.

Just connect it through the Coaxial out from the CD 33 and then into the Matisse. Wow ... what a BIG difference! Vocals are far better than before with good spacing effect and openess. More details are provided ... very nice.

There are a couple of things that I need to clear out.

1. What is I/V Resistors?
2. What is the I2S line?
3. Do you leave the 0.47u/400v Capacitors on when you connect the DAC signal out?

I am really sorry but I am just not familiar with these terms.

CAT
Koifarm 發表於 2007-11-10 00:58:35 | 顯示全部樓層
Alfcat



Cut or desolder the caps on this side and connect left and right output signal from the DAC-AH to the cut or desolder side of the capacitors.

The grounding of the signal output from the DAC-AH connect to the central groundingpoint on the playerboard.

If this is working good. A later mod can be not using the opamps on the DAC-AH board. But get the signal of the I/V resistors.

Best is to use a seperate transformer for the DAC-AH board.
alfcat 發表於 2007-11-10 14:32:23 | 顯示全部樓層
Dear Koifarm,

I have the idea on where to connect the SIGNAL OUT now and the ground. However, still no idea where I input the SOURCE to the DAC.

When Standalone, the DAC accepts COAXIAL and OPTICAL. But now I have to feed the signal from the CD 33 onto the DAC-AH board. How should I do that.

I still have no idea what is the I/V Resistor.

Enclosed are the photos of the DAC-AH.

CAT

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viewer 發表於 2007-11-10 18:20:38 | 顯示全部樓層
hi alfcat,

when you fixed it with your cd-33 i suggest you to replace all the sanyo e-caps(greed colour) and add 0.1uf film cap in parallel with philip 22uf e-caps(blue colour). and add the heat sink on the 8 pics of TDA1543 because the working temperature of those around 55c. if no add it will be easy burn.
after this mod, the sound quality will be 20% up.

thanks.
Koifarm 發表於 2007-11-11 01:08:32 | 顯示全部樓層


See the picture for connection to the I/V resistors. Then you do not use the opamps.

Just connect Cd player digital out to DAC-AH digital in.
viewer 發表於 2007-11-12 17:47:13 | 顯示全部樓層
alfcat,

the DAC-AH layout is here:

for your reference.

thanks.

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viewer 發表於 2007-11-12 17:48:59 | 顯示全部樓層
alfcat,

the dac-ah 反相修正圖( pcb 底面) is enclosed

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viewer 發表於 2007-11-12 17:51:10 | 顯示全部樓層
alfcat,

DAC-ah 修正後面

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viewer 發表於 2007-11-12 17:52:51 | 顯示全部樓層
alfcat,

DAC-ah 修正後前面 PCB.

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alfcat 發表於 2007-11-12 22:13:30 | 顯示全部樓層
Dear Viewer,

I will take a look at the DAC-AH PCB after Wednesday earliest. These few days are really working like a DOG.

Thanks for the inform. After I finished rushing everything this week, I will post the photos of mine DAC-AH for you to take a look.

CAT
 樓主| Kiko 發表於 2007-11-13 08:59:34 | 顯示全部樓層
Hello,

before updating a part of a very huge archive a tip for everybody who has to rearrange and resize pics easily and fast:

http://www.faststone.org/FSResizerDetail.htm

Its free, contains no Adware and no Spyware and is very helpful.

Here the result of this little prog:
 樓主| Kiko 發表於 2007-11-13 09:07:06 | 顯示全部樓層

..

Preparing the material for CD66 and the Xiang Sheng 708B Headphone- / Pre Amp

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 樓主| Kiko 發表於 2007-11-13 09:14:49 | 顯示全部樓層

....

Basically AudynCaps Plus of a german manufacturer, Panasonic FC Caps, Vishay-Dale CMF-55-143 (non-magnetic, military specification) resistors whereever possible, as alternative resistors Yageo, if a value or power rating didn*t have been available.

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 樓主| Kiko 發表於 2007-11-13 09:19:39 | 顯示全部樓層
A little bit of everything...

The tubes and tube sockets are for the headphone amp.

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 樓主| Kiko 發表於 2007-11-13 09:37:19 | 顯示全部樓層
The voltage suppliers: LT1085 is a 5V, the LT1084 a 3.3V, both high precision and very fast.

Details are here:

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1040,C1055,P1278,D2603


Remenber the maximum input voltage of LT1084 is under the reference voltage of the CD66.  A failure at wiring causes the damage of the LT1084 and the DAC!

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 樓主| Kiko 發表於 2007-11-13 09:46:03 | 顯示全部樓層
Some NOS Cornell Dubilier Aluminium foil Capacitors, WIMA MKP-10 Series polypropylene Caps, an OPA Modul with 2 OPA627 (one is below) and some ultrafast sinterglass Avalanche Diodes Vishay BYV27-100 diodes with 15 nsec. in US Military Standard


Datasheet:

http://www.ortodoxism.ro/datasheets2/5/0wg23dl397lgelgw2xxxyeo3lhyy.pdf

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 樓主| Kiko 發表於 2007-11-13 10:13:56 | 顯示全部樓層
NOS Caps have the same problem, the oil becomes hard, but it is a real aluminium foil.

They sound very very good.

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 樓主| Kiko 發表於 2007-11-13 10:17:10 | 顯示全部樓層
such a long foil in that small cap :shock:

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 樓主| Kiko 發表於 2007-11-13 10:35:54 | 顯示全部樓層
Remember there is a mistake: Dont connect the input of the LT1084 with the central input of CD66 (22 V), which comes out of the bigger resistor (the green 2 watts)!



The rest is ok and I hope good to see.

Note: Some of the Pan FCs are soldered with distance to the board. Some circuit paths are only on upper side of the board, so I wasnt sure of making good soldier joints. As a result I soldered and meassured them on both sides separately.

If the circuit paths haves been ONLY under PCB the FCs can be fixed without distance.

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 樓主| Kiko 發表於 2007-11-13 10:42:02 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 10:43:36 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 10:50:29 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 10:55:01 | 顯示全部樓層
after the crash

(the resistors are for the headphone amp)

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 樓主| Kiko 發表於 2007-11-13 10:57:06 | 顯示全部樓層
...Price without tax is:

PCM1742KE - 3,39 Euro - 4,95 USD / piece

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 樓主| Kiko 發表於 2007-11-13 11:01:20 | 顯示全部樓層
The small SMD ADAPTER PCB "RE931-02" is from Italy made by ROTH ELEKTRONIK.
Price is 5,09 Euro without tax.

http://de.farnell.com/jsp/Sockel,+K%FChlk%F6rper,+Prototypenentwicklung+und+Statikschutz/Prototypenentwicklung+und+Leiterplatten/ROTH+ELEKTRONIK/RE931-02/displayProduct.jsp?sku=1426162

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 樓主| Kiko 發表於 2007-11-13 11:03:50 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 11:12:55 | 顯示全部樓層
If you have to connect a new DAC you can use fine silicone wire, the rubber of usual wire disappears by soldering if the soldering gun is too hot.

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 樓主| Kiko 發表於 2007-11-13 11:20:21 | 顯示全部樓層
The 3 resistors under the cover are at close quarters and to connect to the DAC. Use heat shrink tube for isolation.

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 樓主| Kiko 發表於 2007-11-13 11:22:23 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 11:24:01 | 顯示全部樓層
The soldering takes long time.

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 樓主| Kiko 發表於 2007-11-13 11:32:52 | 顯示全部樓層
Instead of the old green resistor you can use higher values as 2.2 Ohms.
2x 6.8 for one voltage supplier and 5.0 for another. The two heater are not as cooler as I wanted them to be. Test and user higher values here!

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 樓主| Kiko 發表於 2007-11-13 11:40:38 | 顯示全部樓層
the PSU / Digital board...with a lot of space for small 5mm Caps

The Vishay high speed diodes cannot substitute all diodes, because of their values 100 V 2.0 A.

Therefore you can add some caps under consideration of the values.

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 樓主| Kiko 發表於 2007-11-13 11:42:41 | 顯示全部樓層
Provisorily fixing the rubber mat from a sporting goods store with adhesive tape.

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 樓主| Kiko 發表於 2007-11-13 11:44:16 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 11:48:18 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 11:50:24 | 顯示全部樓層
...

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 樓主| Kiko 發表於 2007-11-13 11:57:42 | 顯示全部樓層
End of first part.

A low jitter clock should come.............soon.

At this moment I can assure that it is an improvement in every sense: Bass is deeper and has an interesting contour, the mids and hights are much more precise and have more openness, the whole presentation is more an adult presentation as before. The music has a flow like water, with a exciting atmosphere.


Thank you,

Kiko

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 樓主| Kiko 發表於 2007-11-13 21:36:41 | 顯示全部樓層
I know that is a thread for MHZS gurus.


Please allow a little addition, I have modded them together.



The little nice Xiang Sheng 708b is interesting for audiophiles, because is has an good layout but cheap components. ..................A small review of totally rebuilding.

I believe this amp must have his origin here:

"The Morgan Jones Mini Tube Headphone Amplifier"

http://www.headwize.com/projects/cmoy5_prj.htm

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 樓主| Kiko 發表於 2007-11-13 21:47:02 | 顯示全部樓層
Some tube sockets have a wick in the middle which has to be cut off.

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alfcat 發表於 2007-11-13 21:48:49 | 顯示全部樓層
Dear KiKo,

Haven't seen you for a week and you were hiding in your garage to fix this whole thing.

Looks very interesting to me but honestly I lost track as you proceed.

As an amateur, I realised that you added some huge capacitors. You did this to ensure a steady flow of power to the DAC / Analog part? Instead of using an extra Power Supply, you can capacitors instead?

If you can afford the time, can you explain a bit on the logic of going through each and every step? I know that you added in a lot of stuffs but I don't know what is the purpose of adding them ...  :cry:

CAT
alfcat 發表於 2007-11-13 21:56:33 | 顯示全部樓層
To Viewer,

I dis-assembled the DAC-AH today after work. It looks like they haven't fix the "out of phase" problem afterall. My PCB looks exactly like yours to me.

I post the photo of my PCB with this message for your reference.

I can follow some parts of your photo but the second one is a bit too small and looks like it is out of focus. It seems to me that you scratched the PCB in order to solder something in.

On the Top View, you replaced TWO items with a diamond formation of the PHBY diodes. What is the purpose of doing that?

Wow, you use Mundorf 0.1uf caps on top of the Philips ones? How much did you pay for them?

CAT

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