[eclein]

Every part would have to be "quantum purified", kissed by a virgin and blessed by a priest, and even then, $500 max.
 
Steve

Double quantum purified

[wushuliu]

Sure does look familiar. Some of the capacitors they replaced with OSCON SEPC caps on the stock board went into positions where the stock caps were 20V and some maybe 25V, however the data sheets for the OSCON SEPC series shows a max rating of only 16V. Wonder if they will last long, unless the stock caps are over-rated to begin with. Wow, they also sell "quantum purified" digital cables.

I believe the stock caps are rated higher than the supplied voltage, yes. Assuming you're talking about the Jfet I/V stage, I believe it gets around 15v or something like that.

Apparently the Mojo Audio mods include major changes to PS, including supplying 40k uf. Can that much extra power be of benefit for a DAC?

I'm not gonna bash the guy for charging that much though. We all gotta eat. Just glad I'm handy with the iron!

[srb]

Apparently the Mojo Audio mods include major changes to PS, including supplying 40k uf. Can that much extra power be of benefit for a DAC?

I've often wondered how robust a power supply needs to be for a DAC.  I don't know if it's a numbers game or not, but Audio-gd uses > 50,000 uF capacitance in their DACs and Wyred 4 Sound use 88,000 uF in their DAC1/DAC2.
 
I'm guessing that the DAC and receiver chips are very sensitive to DC ripple and can benefit from the large capacitance for smoothing as opposed to needing it for energy reserve.
 
Steve

[SET Man]

Hm. $2500 AD1865-based DAC.

http://www.mojo-audio.com/AD1865NOS-D-A-Converter-AD1865NOS.htm

If you enlarge the interior photos, that board suuure does look familiar!

Hey!

   Wow! The chassis must have cost a lot Well, at least there are some improvements and upgrades... unlikely the Lexicon relabeled Oppo

Take care,
Buddy

[wushuliu]

I've often wondered how robust a power supply needs to be for a DAC.  I don't know if it's a numbers game or not, but Audio-gd uses > 50,000 uF capacitance in their DACs and Wyred 4 Sound use 88,000 uF in their DAC1/DAC2.
 
I'm guessing that the DAC and receiver chips are very sensitive to DC ripple and can benefit from the large capacitance for smoothing as opposed to needing it for energy reserve.
 
Steve

Well for kicks I swapped out the 4700uf Nichicon Gold Tunes from the AD1865 DAC and replaced them w/ some 15000uf and 18000uf caps. There was a noticeable improvement in sound quality.

What i want to know is if it is possible to add something like a shunt regulated PS *before* the DAC, or would I need to bypass the regulators that are already on board?

[parodielin]

Plan to embrace the AD1865K project in the next few months.  Based on the read, I'd need the following items to make a stock DAC work:

- Power Switch (DPDT) (Do I need a fuse?)
- RCA jacks for output
- Do I need a jacket for Coaxial?  Is that the same as RCA jack?  Did it come with the kit?
- Some wires.
- LEDs - can I wire LED to the board so I know the machine is on?

I plan to use my old pioneer universal dvd player as the transport with a coaxial out to the DAC for two channel music.  I might add a USB to coaxial converter later if I see the improvement vs. the old pioneer player.

I will put these on a MDF board first.  Might add a metal enclosure if I like it.

Did I miss anything?

[wushuliu]

Plan to embrace the AD1865K project in the next few months.  Based on the read, I'd need the following items to make a stock DAC work:

- Power Switch (DPDT) (Do I need a fuse?)
- RCA jacks for output
- Do I need a jacket for Coaxial?  Is that the same as RCA jack?  Did it come with the kit?
- Some wires.
- LEDs - can I wire LED to the board so I know the machine is on?

I plan to use my old pioneer universal dvd player as the transport with a coaxial out to the DAC for two channel music.  I might add a USB to coaxial converter later if I see the improvement vs. the old pioneer player.

I will put these on a MDF board first.  Might add a metal enclosure if I like it.

Did I miss anything?

A fuse is always a good idea.
A jacket? You can use an RCA jack for the coaxial or if you want to be
precise about the impedance there are RCA jacks specifically for spdif. You
can find one at VHAudio for instance. Doesn't come w/ the kit.
The board has an led. You will have to replace it and use desired length wire
for chassis mounting.

[waltsok]

I want to do the ad1865k shortly. I have never had a dac before but I do know I will also need some kind of source. What type of source or transport will i need to play cd's. Will a blu ray have appropriate out? Obviously I am new to this Thanks

[parodielin]

I want to do the ad1865k shortly. I have never had a dac before but I do know I will also need some kind of source. What type of source or transport will i need to play cd's. Will a blu ray have appropriate out? Obviously I am new to this Thanks

I learned this not too long ago. 

As long as the machine has a Coaxial output, it should be OK.  That's what I plan to do with my dvd player.  I also plan to add a USB to SPDIF converter to play all my computer file based music.

[wushuliu]

I want to do the ad1865k shortly. I have never had a dac before but I do know I will also need some kind of source. What type of source or transport will i need to play cd's. Will a blu ray have appropriate out? Obviously I am new to this Thanks

If you've never had a dac maybe you should take a listen to some retail ones before jumping into the ad1865 kit. At the very least try out some OverSampling vs. Non-OverSampling dacs. There are so many choices and the differences between OS and NOS are worth exploring before expending time and energy into a kit. Just a thought.

[wushuliu]

Another option that I wish existed before I bought my dac is this:

http://quanghao.com/product.php?id_product=9

It's an AD1865 board incorporating the Salas (of diyaudio) shunt-reglated power supply. The DAC circuit should be similar to the rainbow as they are both based on Andrea Ciuffoli's design. The Salas PS gets kudos and is guaranteed to be far far better than the rainbow design. And you dictate the parts quality, so end result will be in your hands.

For the IV stage, a tube-based design is also offered on that site - but another option to go easier on the wallet is rainbow's tube IV stage:

http://cgi.ebay.com/DAC-I-V-conversion-module-SRPP-tube-module-/320572208796?pt=LH_DefaultDomain_0

I'm trying to not to give in to temptation with trying this out but the chance to control all the parts myself and use Salas' PS is almost too much...

[parodielin]

I looked at this one and I'd really love to build one.  But, but, but, it's not for beginners and the cost will be higher I guess...  Not really know how to manage it.  There are many interests in DAC End but very few build thread that I can locate...

For example, the kit (http://quanghao.com/product.php?id_product=1) is $350.  Does it come with Salas? 

Another option that I wish existed before I bought my dac is this:

[wushuliu]

I looked at this one and I'd really love to build one.  But, but, but, it's not for beginners and the cost will be higher I guess...  Not really know how to manage it.  There are many interests in DAC End but very few build thread that I can locate...

For example, the kit (http://quanghao.com/product.php?id_product=1) is $350.  Does it come with Salas?

No, not for beginners. The completed board you linked is the same board, so yes it's the Salas PS.

Should not be too expensive though w/ the raindrop IV instead of the quanghao tube version. Probably $300 or less.

For anyone comfortable with a soldering iron, though, I think it's a great deal.

[parodielin]

$300 or less?  I thought the kit costs $350.  Do you mean that buying the PCB and BOM yourself out?  I haven't tried that yet but $300 or less I am a bit comfortable with.  Do I still need a two stage Transformer for the DAC End?

No, not for beginners. The completed board you linked is the same board, so yes it's the Salas PS.

Should not be too expensive though w/ the rainbow IV instead of the quanghao tube version. Probably $300 or less.

For anyone comfortable with a soldering iron, though, I think it's a great deal.

[wushuliu]

$300 or less?  I thought the kit costs $350.  Do you mean that buying the PCB and BOM yourself out?  I haven't tried that yet but $300 or less I am a bit comfortable with.  Do I still need a two stage Transformer for the DAC End?

Yes, just buying the PCB and getting the parts yourself. Don't quote me on that as I have not actually calculated the BOM, just guesstimating.

No, you're transformer needs may be more complicated, depending on what you choose for the IV stage.

In your case, unless you're really up for it, I would stick with the rainbow kit... argh, i mean raindrop.

[parodielin]

Nothing compares to BOM yourself. 

Here is the BOM:

http://www.diyaudio.com/forums/quanghao-audio-design/169318-first-run-dac-end-support-2.html#post2230137

Yes, just buying the PCB and getting the parts yourself. Don't quote me on that as I have not actually calculated the BOM, just guesstimating.

No, you're transformer needs may be more complicated, depending on what you choose for the IV stage.

In your case, unless you're really up for it, I would stick with the rainbow kit... argh, i mean raindrop.

[jema]

Hello!

Thanks for this awesome thread!!

I have some Q regarding your, in general good, description of mods;

You say;

I have just replaced the Panasonic FCs in the AD1865 DAC w/ Os-cons, and clearly it's what I should have done in the first place; the 'dark' sound is all gone and what I am hearing now is really, really good.

Q1: Which ones are the Panasonic FCs? Is it the ones that Lampizator describes as "Silver caps"? ie C12, C5, C8, C10 and two C14?

You say;

I have replaced the diodes by the power supply w/ fast 1A Schottkys

Q2: Did you change all 16 of them? Which Shottky is it, the one with 25ns recovery time?

You say;

swapped out half the resistors in the I/V stage for PRPS and dales and half the caps for Elna Silmic II.

Q3: Okey, you really should elaborate that. Which ones did you swap with which ones? I can't find anything about "PRPS", so please elaborate, also tell me where to find them.

Q4: I bought a tube I/V-stage from raindrop-hui - any wisdom to add about it? Herer it is: Ebay Link

Q5: Someone talked about LM317 regulators, I can't find any on my board. Only "B1020A" and "LT1084" and some unreadable! Did I get a different pieace?

Q6: Can you tell me how this is bridged? It looks as if 1 is connected to 2, and 3 is connected to 4 in this pic...


Here is a pic of my tube-stage;



Best Regards, Mattias
Sweden

[wushuliu]

Hi Mattias.

1. I used the FCs to replace the silver caps (see post 90). Then I replaced the FCs w/ the Os-cons.

2. I replaced all Schottkys with On-Semi MUR120.

3. Most important resistors to replace are the 100 ohm output resistors by the output caps, just before the L/R output. If you want specifics then PM me or wait a few days and I will try and put up a pic indicating which resistors. PRP resistors are available from Partsconnexion and Hndme.com, but you can use whatever type you prefer.

4. Hm, don't know much about the tube design.

5. ? which post talks about the 317? Are you sure that is not in reference to the other
DAC, the Gigawork?

6. 1 is not connected to 2. I am also pretty sure 3 is not connected to 4. Just
a trick of the light in the photo.


w

[jema]

Thanks for very quick reply!

[wushuliu]

Hey!

    I have this DAC in my system right now. Bought from this seller, great seller by the way.

    This DAC use 4 TDA1543 DAC chips running in paralleled. The output come directly off those chips. There is no opamp or buffer after the DAC chips. Simple! I like it.

  The DAC uses lot of good quality component despite the price. Still I only did 2 upgrades to it. 1. Changed diodes to Schottky type 2. Changed the output caps (22uf) to Russian K73-16 22uf 63V with Jensen PIO Copper as by pass caps.

     Definitely the output cap upgrade made the biggest improvement. The stock caps sounds horrible. But I know NOS DAC so that was the first thing I looked at to upgrade.

    So far a great NOS DAC. But not for everyone. It won't do detail especially in the high like 24/96+ DAC. But I'm a fan of NOS DAC of which I feel sound more analog playing Red Book CD I found most 24/96+ DAC sound unease especially in the high that sometime can sound hyper unnatural. Of course they are some exception of good 24/96+ DACs out there.

    Anyway, I will take some pictures and post them here soon.

Take care,
Buddy

Thinking I may give this a shot for the heck of it. It's so cute!