If you are using digital media, you’ll use a DAC. Depending on how you store your music, this will have a bearing on how you interface this digital data out. Every format has its pros and cons, so let’s have a look here.

For digital media, to my knowledge, you have 3 choices today. SPDIF, USB and Firewire.

SPDIF is the de facto standard digital output. It’s available on CD/DVD players as “Digital Output”. Many media players like the Squeezebox has this too, as well as many PC soundcards. SPDIF even has an optical version, Toslink. A sonic upgrade can be experienced instantly if you ditch the lousy RCA socket and opt for BNC. Why oh why does everyone still use RCA then? For convenience rather than sonic reasons!

A major problem with SPDIF is that the SPDIF receiver in your DAC got to retrieve the clock signal from the incoming SPDIF. And this is a major problem. The older but still very popular obsolete CS8414 has a typical 200ps while the modern DIR9001 manages much better at 50ps. Irrespective of what comes after this, the fact that the recovered clock isn’t optimum will have a huge bearing on sonics later.

USB DAC is really popular these days. The most popular implementation is Texas Instrument’s PCM27xx chips. These are pretty good “as is” but still a lot can be improved on. Again, there is the question of how is the clock recovered?

There are better implementations of USB which do not use TI’s generic PCM27xx chips but I haven’t tried these yet.

Firewire is said to be the best but far from readily available. And too expensive at this point.

Which interface to use also depends on what is your source. If you are using CDs, SPDIF is most logical solution. If you store your music on hard disk, then USB or I2S via a SD card player is viable. The above briefly describes the pros and cons while the convenience of which format is really up to you. If you don’t mind a little trouble, go for the best sound!

My current favourite, however, isn’t any of the above. It’s via I2S! Provided you have a very good I2S source!

I started dabbling with I2S when I tapped out this signal from my old Marantz CD63 way back in 2003. The CDM12 transport isn’t that great and though the sound was already a huge improvement over SPDIF, there is still something lacking there. But hey, if you could ditch SPDIF, try this!

Later I played around with USB-I2S as well as USB-I2S-EIAJ in USB Monica. As good as all these sound, it’s still not a pure I2S solution. The interface is still via USB. You could say the weak link is how the PCM27xx chips derive the I2S out. I hope to have the resources to tackle a better way of doing USB one day…

Anyway, my current favourite digital player (The Digital Turntable) has, in my mind, the most direct route to I2S. A DSP chip reads WAV file data from a non-moving media (the SD card), then outputs I2S signal which is fed to a CS8405 chip to generate SPDIF. Both the DSP chip and CS8405 is clocked by a low jitter clock.

Since a good quality I2S is available, feeding directly to an I2S DAC chip (or through Black Crow for an EIAJ DAC chip) is all we need! Replacing the clock with a lower jitter implementation (like Kwak clock below or the plug-n-play Tent XO module) and I assure you your jaw will drop listening to music through this combo!

Okay, okay, enough about all this. So these are what we have here.

Above pics show the 3 implementation, coupled to mojo. They’ll couple nicely to mojo2 as well. mojo/mojo2 PCB has 6 PCB holes which couple nicely to the I2S-EIAJ, USB-EIAJ and SPDIF-EIAJ modules.

4 are EIAJ signals while the right 2 are your power connections to power the modules.

So instead of forcing you to buy a USB Monica or a SPDIF Monica, you now have choices and since this is in module form, you could play around slowly.

Hey, if there’s sufficient interest, how about an EIAJ selector to select from multiple inputs?

The post Let’s pay some attention to our Digital Interface appeared first on diyparadise.

The culmination of all the hard work, experiments and listening tests of all the DIYers here! Most significant tweak has to be the “3 transistor mod” suggested by Paul Needs and Paul Hynes. Who would have thought we have such a bottleneck there? A major major upgrade in sonics in every way!

Shown here built up with the Paul Hynes regs and CCS2 plus 3 Audioslaves for the I/V stage.

Now offering mojo2 PCB.

Note that only one supply is needed as the PCB traces provide power to the individual regulators.

The PCB has been designed to fit Paul Hynes CCS2 and Regulators particularly the 5.4V and 0.83V regs. So no more string of diodes etc. If you prefer the simplicity of the original mojo, it is still being offered for sale. If you are budget conscious, you could build whichever reg you prefer and fit into mojo/mojo2.

mojo2 kit.

The kit has all the SMD components (resistors, capacitors and ferrite beads) soldered on so you only have to mess with the through hole components. [yes, thanks for the applause!]

It has everything you need except — regulators, Black Gates capacitors and output coupling capacitors. Oh yeah! Solder, elbow grease and the most precious commodity of all – time.

mojo2 map.

The map above shows CCS2/5v4/0p83 regulator pinouts.
If you fit in the Paul Hynes 5v4 regulator at “5V” location above, you only use Output and Ground.
If you are budget conscious, you could use Audioslave here or even a LM/LT1086-5V regulator as the pinout is the same – I, O and Gnd.
The rest of the regulators are straight forward.
The 12V and 18V regulators share the same pinout as the 5V reg, namely I, O and Gnd.
If you don’t want to use regulators here, just short I and O together but be careful with the CCS2 as it can’t take >17VDC.

However, due to the tight fit, the electrolytic capacitor of the CCS2 may come into contact with the solder joints on the 0.83V regulator, a simple suggestion of insulation tape on the top of the capacitor should do.

As mojo2 accepts EIAJ input, you could just feed EIAJ signal to it directly. Shown here is my current favourite digital player! Sounds best on a chopping board!

Though not shown, the ribbon cable feeds directly to the EIAJ input of mojo2.

The QA550 SD card WAV player reads bits and bytes directly from your SD card where a DSP chip does all the hard work here. This chip then outputs I2S signal to a CS8406 I2S to SPDIF convertor then outputs SPDIF downstream. This is where you hook up your DAC and let your digital receiver process this SPDIF and extracts I2S/EIAJ signal back to feed to your DAC chip.

Now, we could circumvent all this data processing and simplify it. All the attendant processing can’t be good for the signal no? Since there is already I2S signal onboard (straight from the DSP chip), we could feed to our I2S-DAC chip!

Monica’s TDA1545A requires EIAJ so here comes Black Crow! An I2S to EIAJ convertor board.

The above shows Black Crow’s pins directly mounted on the I2S pads of the QA550 which its designer very nicely provides us. The oscillator was also removed and now fed by a single supply version of a Kwak Clock 7. I’m too lazy to build one so I bought some DIYer’s version. [Thanks Patrick!]

So how’s the sound?

Going I2S is worth it! Installing the Kwak Clock (or some other low jitter design) pays off well!

Dare I say it?! Digital has never sounded so analog!

The post What’s better than mojo? mojo2! appeared first on diyparadise.

Hello DIYers.

You may have came across my USB Convertor. That was meant as a temporary solution while I crack my head over a proper USB DAC. The USB Convertor outputs SPDIF (your vanilla digital output) which you could then feed your DAC. Now if you are looking for a dual usage DAC (meaning for both computer and CD/DVD player type), then this will be a good, albeit compromised, option.

However, if sonic quality is your utmost concern, then there is simply no business converting from USB to SPDIF then to DAC format again.

Therein lies a problem. Almost all the USB receiver chips in the market I know only outputs I2S and not the EIAJ format required by Monica’s TDA1545 chip. Boy, this isn’t fun.

I built a few circuits to convert I2S to EIAJ but wasn’t successful. More studies later… then I realized I need to climb up the highest mountain in this region, consult the guru there and sprinkle some pixie dust.

Nah, the guru wasn’t much help. In the end, after lots of diligent nights (and wee early morning hours) of pouring over datasheets and building prototypes, I finally got it done.

USB – I2S – EIAJ – Monica!!!

Let me be anal here and declare this as the first USB DAC using an EIAJ based DAC chip!

[You could make me fall flat on my face with big dollop of humble pie by pointing out to me which USB DAC in the market that uses an EIAJ based DAC chip.]

So what’s the big deal you may ask? Well, as always in audio, less is indeed more. Going through one less data conversion, the gain in sonic quality is…. va va voom! Like the real Monica!

If you are new to computer audio, I suggest you take a read of my computer audio pages.

So this PCB consists of a USB receiver chip, an I2S-to-EIAJ convertor and asynchronous reclocking scheme, TDA1545A circuitry and of course, Rudolf Broertjes’ SS I/V Gain Stage. All in one smoking PCB!

Simple enough eh? It looks simple from the top but underneath, there’s quite a lot of surface mounted components soldered on.

You could power her at 12VDC though 18VDC is said to sound better especially for the SS I/V stage. If you intend to go this high, I’d suggest heatsinks for the LM317 chip.

Better still, note that L3 is a diode instead of an inductor or ferrite bead. If you remove L3, you could power TDA1545 circuitry through J2 and power the SS I/V stage circuitry separately through J4. How about that? ; )

Wiring is very simple. Just hook up power supply (you provide of course), and output to RCA sockets of your choice. Input is simply USB from your PC. I’ll suggest a USB cable of type A jacks and off you’ll go!

No software to install, and no PC casing to dismantle.

Why heck, install both USB Monica and Charlize in one little case and you’ll have a smoking PC audio system!

Due to complexity of build, no kit is available yet. Assembled/tested USB Monica could be purchased from our e-Store. http://store.diyparadise.com

For once, let’s end it short and sweet.

And spend more time with Monica!

Update on 27 Nov 2007!!!

Plug and Play USB Monica in hard wood chassis like Monica 3 available now!

Enhanced PCB featuring some changes ala Monica 3. Note the Super E Black Gates… Yummy!

The post USBMonica appeared first on diyparadise.

CDM12 Controller Kit

Yo folks! Ever since I got my CDPRO2 up and running, I’ve been playing a lot of attention to the front end of the system. The front end to me, is more important than the rear end (unless your name is Kylie M). Of course, if you have junk speakers, you can’t hear what you are supposed to hear, but then if you have junk front end, there is nothing to hear at all!

There are a few truisms in audio that has, time and again, proven to be “true-er than others”. One of those is “Thou shalt not believe everything this yeo guy says”. Another more useful one is “where there is less signal processing, the sound is always better”.

Now I’m sure many have put forward the above truisms (including the one about that yeo fella!), but I had direct experience with the later when I hooked up the I2S signal from my CDPRO2 to my TDA1543 (let’s call this Route 1) and compared this with listening via the SPDIF output (Route 2). Using SPDIF, we need to use a digital receiver like CS8412 to convert the signal back to I2S, then only feed TDA1543. As you can see, there is some processing going on, converting the internal I2S to SPDIF, then SPDIF back to I2S when using Route 2. Which is pointless if we could tap I2S directly ala Route 1. Now the sonic difference is not subtle if this idiot can hear it! The sound is more “live”, more immediate, has more prescence. And I think this is all because of less signal processing. Comprehende?

All this is fine and life goes on beautifully until I discover TDA1545. Man, to my ears, this is a much better DAC overall and the next thing I know, I got anal and began fretting about signal conversion I2S-SPDIF-EIAJ. Yes, EIAJ is the format required by TDA1545, so I have to resort to using the endangered species CS8412 again. And I worry about the sonic degradation with all this signal formatting again. Grr…

So I yearn for a way to tap the EIAJ format directly from the CDPRO2. Studying its manual, it seems that the IS2 port’s output format is selectable via software and ONLY software. By default is I2S. The controller that came with my CDPRO2 kit doesn’t have any provisions for this so I’m left to programming a controller myself or the less glamorous option — seek help.

And so came Calv Acoustic Labs to the rescue! Again! Apparently while I was busying myself with all this hoo haa, our master DIYer has already been toying around with a controller for transport units based on the Philips CDM12 family. This includes Short Loader Mk3 used in Marantz CD4000, CD5000 and also our venerable CDPRO2. I wonder can I say “great minds think alike” just because I share the same idea as Calv Acoustic Labs’ head honcho, envisioning a controller that could select different signal formats? But there is a difference. While I pleaded for help, he programmed it! Now you know why I’m forever doomed as a novice diyer…

In addition to the controller, PCB, cables and connectors, the kit also comes with relevant info, like board layout, pin connections, wiring blah blah blah. Since I’m such a nice chap, I was lent a LCD display module.

Wiring everything up is pretty straightforward. The only thing I had to build myself was a 9VDC supply for the CDPRO2 motor. I could use my existing one but it’s too big. You’ll know why in a moment. Back then, I used to have a problem with Stocko connectors but guess what? I grew up! Now I find it pretty easy to use. Hee hee… And before you know it, I got everything wired up and running! [Note the ** DIY Paradise ** on the LCD display. Everyone knows I’m so full of myself!]

Close up of the PIC controller. Please forgive my home-made insulator…

Fitting everything into a small chassis. Another truism in audio. Never use a chassis too small… Real estate at the front and back portion will be utilized very soon!

So it works! Of course it works! Note that the “lent” display is too big to fit into the chassis. The hunt begins for a much smaller HD44780 based LCD display. Anyone?

Finally, with rest of the gang! I can tell you it made a very pleasant debut. Hee hee…

Right now still using SPDIF but this little monster of a TDA1545 DAC will be fitted into the chassis soon, and will be directly driven from the I2S port.

Aha! Now this is the beauty of this kit! Right now driving TDA1545 DAC which requires EIAJ format. Through clever programming, by pressing both “Play” and “Stop” keys simultaneously at power up, the I2S port is programmed to output EIAJ! The non-volatile memory of the controller is written so this will be EIAJ until it senses certain combination of “Play”, “Stop”, “Prev” or “Next” keys being pressed at power up. The various combination of these keys will give between I2S FS, I2S 2FS, I2S 4FS, 16-bit EIAJ FS, 16-bit EIAJ 2FS, 16-bit EIAJ 4FS, 18-bit EIAJ FS and 18-bit EIAJ 2FS! So it’s really up to you whether you want I2S or EIAJ at their various sampling frequencies. Cool eh?

Anyway, I prefer a one-box solution rather than playing around with so many boxes, like Thoreau, “Simplify! Simplify! Simplify!”. However, feel free to apply your engineering acumen to build “state of the art” machines of your choice. Now, if you wire the I2S/EIAJ output to a PC modem connector, you can then have your own dedicated DAC for optimum power supply isolation blah blah blah… You know, like this USD42k+ combo… (Click on image to read review by 6moons)

But you can do better! You can build various DACs and just select which format/FS you want, depending on which DAC chip you prefer at that instant. Ahhhhhhh…. This is better than sex!

Okay, if you have a CDPRO2 or planning to have one or planning to DIY a CDP based on the CDM12 family, and you just want to have your mojo with all these adult toys, you know who to contact. Calv Acoustic Labs at vt4c at hotmail dot com.

WELL DONE vt4c!

PS: Please note that my PCB is the prototype. A nicer version is available directly from Calv Acoustic Labs.

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