Hey! If you haven’t been to my site for a while (and I haven’t updated it for a while), you will notice the site has been revamped. I hope you like it better now. And here is my first article on this revamped site.

I wrote 2 articles on Computer Audio few years ago, Computer Audio Is So Much Fun which focused on the hardware side and a follow up article on the software side.

That sure feels like a longggggg time ago.

I’d be an idiot if I haven’t changed anything since then!

You see, you could use vintage gears every where but when it comes to digital, it doesn’t make sense to stay “vintage”.

Over the years, I have changed a few music machines, from the first generation Mac Mini, to a plastic  iMac (earlier gen) and now this Intel Next Unit of Computing.

Wait a minute! Have I abandoned the Mac world?

Hardly!

I got to know a local Mac expert and this boy (he is only 17!) made a Hackintosh out of this CPU.  You see, I find the strength of Mac lies in its software, not its hardware. Enter this CPU.  This little fella is even smaller than my previous Mac Mini (it’s only 4″ by 4″) and still packs quite a punch. The version this kid did for me has a 32GB SSD hard disk inside so it boots up really fast. I pimped it by adding more RAM so it runs on 6 GB RAM now. All music files are stored on an external hard disk.

It has a mean Thunderbolt port, as well as a HDMI and 3 USB ports. I’m not using the Thunderbolt port now but will do so in future when I get a Thunderbolt Hard Disk. So this guy feeds my Discreet Monica which has been rebuilt into a nicer chassis. It’s a wine bottle box…

Moi belle Discreet Monica has the Amanero USB-I2S convertor as the USB receiver.

On the software side, I’m totally gaga over Pure Music Player!

Simply awesome!

With my Hackintosh, I have more RAM than necessary so it’s really nice to be able to use the Memory Play feature. With Memory Play, the audio track is read, then placed into RAM and music is then “streamed” off your RAM. Thus, the impact of reading off  hard disk is minimized. Anyway, that’s the theory behind it. But how does music sound with Memory Play?

Music just sounds better! It’s like you improved your power supply and you reduced your jitter. The hard edges most noticeable in badly recorded music is greatly reduced, resulting in much0-welcomed smoothness and ease on your ears. On well recorded music, the impact is subtle but noticeable.

Another reason to like the Pure Music Player is the ability to play FLAC and DSD files! As you know, in the Apple world, FLAC is like a dirty word. Stock standard iTunes just wouldn’t play FLAC but PMP allows you to play and ride on it. DSD files is converted to PCM on the fly for you so your PCM DAC is still usable.  Since the Amanero supports DSD, I’ll be studying more on this… Ha ha!

So there you go, my current take on Computer Audio.

The post More on Computer Audio appeared first on diyparadise.

My first source was a heavily modified Marantz CD63. this seems like aeons ago. Then the foray to DACs began, first with TDA1543, then TDA1545. you could say that the seed of Monica was being sown around this time.

I later changed the transport to Philip’s CD-Pro2. Wow! Huge jump in sonics. Puts down so many other transports. However, for some reasons which I couldn’t comprehend, my CD-Pro2 module died on me. 2 pieces of CD-Pro2 later, I decided I had enough.

Then the switch to PC audio and hence started playing with a Squeezebox media player. Sonics wise the CD-Pro2 still makes a better transport but the convenience of playing off pc more than makes up for loss in sonics. And yeah, I heavily modified my Squeezebox unit too.

Well everything’s good for now but then… the revelation of the QLS Hifi’s QA550 SD card player! Wow! Immediately you hear the gulf in the sonic quality between the Squeezebox and the QA550. Fed with a Kwak Clock, the sonic improvement is even greater.

So if things are so good now, why fret? Unfortunately the user interface of the QA550 is akin that of a turntable, which is almost zilch. After being spoiled by the user interface on the Squeezebox (including the touch screen Squeezebox Touch), the QA550 is a step back in time…

So the journey for a better source starts again. Damn it.

I have heard lots of good things about the m2tech Hiface but I’m not interested in SPDIF as the I2S interface proves superior (to think that so much time/money/effort has been wasted!).

So John Kenny‘s modified I2S Hiface seems like the perfect ticket! (Unfortunately John isn’t selling the pcb module anymore).

Many many weeks later, finally got it built.

Boy, that one sentence didn’t show you how much work I did.

This is what I did:
As I2S consists of 5 lines of signal, you have to decide on a proper interface. there is no standard interface here so i settled for the RF45 network port which is used by many companies (m2tech, North Star and Zenden etc) too for I2S duties.

So got to build an I2S Monica that accepts I2S input via RJ45 interface.

While doing so, I might as well try this excellent looking “Weipu” connectors for analog signal duties. So this I2S Monica accepts I2S via RJ45 then outputs analog signal via Weipu connectors.

A Beyonce was later built using Weipu connectors. And to have more fun, instead of the Microchip controller I used before, I now put in an Arduino controller. The 8 digit LED display is really cool too.

Hey, since we are already at this stage, I built a new Charlize but using Weipu connectors.

Lastly i had to haul up my old Mac Mini to audio duties and transfer all the music files to a new hard disk.

So is it any wonder I’m so short of time?

Do notice I “standardized” my chassis. These are actually key holders made from recycled rubber wood. [trying to be green … ]

Oh well, finally got everything built and… the sound makes it all worthwhile!

Wait! I’m not done yet.

I also installed the very cool Pure Music Player. Oh my! What a nice software! It could upsample (which I can’t be bothered with) or play native sample rate of your audio files up to 384kHz sampling rate. And the hiface supports all this. If you have to ask, well, higher sampled material sounds better!

Higher sampled music does the highs so much better. At first I wasn’t sure of all the highs but then as you listened, damn in, I’ve been missing so much all this while! Scoped waveforms back this up. [Of course vinyl folks will tell you nothing beats infinite sampling rate. gotta give this to you guy!]

So after all this work, I’ll say everything is worthwhile!

The highs… could give you a high! Have never heard so much highs coming out of the system. This took a while to get used to but now with the silky highs, boy, everything sounds so much better now.

So am I done here? Again, not yet!

My I2S hiface is a Mk2. Apparently John Kenny has just released Mk3, so there’s more mods to be done. And more sonic blasts to be had!

One thing for sure, this won’t be the last time I rebuild my system. That’s the fun of DIY!

The post Rebuilding my system appeared first on diyparadise.

Yeah, this is the Kuala Lumpur International AV Show 2008. Our debut at an audio show.

Note that source is from the Mac Mini on the far right.

St Cloud and the Hedlund Horn. The St Cloud is more suitable for this small room but can’t play that loud due to its 3″ driver. Most of the time we play the Coral Beta 6 in the Hedlund Horn. Most folks when they see both speakers, ask for bass!

Closer look.

2 digital source is used alternately. The modified Squeezebox and the CDPRO2-based transport.

The top rack shelf is for signal path only. Bottom shelf for power supply. Each power supply has its own balanced isolation transformers.

The all-in-one. Perhaps should call it “All or Nothing At All”.

Requires a digital input and output goes to speakers!

The best interconnects are NO interconnects.

Enough about the system! My thoughts are blogged here.

KL International AV Show 2008 – First day

KL International AV Show 2008 – 2nd & 3rd days

The post Our Participation at KLIAV 2008 appeared first on diyparadise.

Computer Audio is Soooooo Much Fun!

Boy, I have been having so much fun with computer audio, or do you prefer the term “PC Audio”? Playing music through a PC is addictive. We’ll look at the hardware side first before going to the software end.

I admit I have been late to this “PC audio party” but as they say “better late than never”! And I’m glad I joined the party! The sonics has so much potential compared to conventional CD playback and most folks believe this is mainly due to much reduced jitter when playing through PC. You see, with conventional CD playback, we almost can’t escape from using digital output (SPDIF) format. The Achilles’ heel of SPDIF has to be the way the critical Bit Clock is recovered from it.

This is the work of the digital receiver (like CS8412, CS8414 etc) and we are limited by how well it recovers this clock signal. CS8412 for example has jitter specifications of Bit Clock of 200ps. Not very impressive! Monica’s asynchronous reclocking (as shown the light by Kunosoki san more than 20 years ago) ameliorates this but it’s no way a solution either.

With computer audio, let’s say this together. “To hell with SPDIF!” Ha ha!

Back to hardware, the Squeezebox is a little computer gadget that appeals to geeks like you and me. It streams (wired or wirelessly) audio files stored on your PC to your hifi system. Of course, if you do it wirelessly, you could have your noisy PC in one room and your hifi set in another. Wonderful!

To be honest with you, I know nuts about playing music through a computer but ever since I got a Squeezebox, have to start a crash course on it!

Fancy having a dig at DIYing your own Squeezebox? Well Ole Schüsseler here shows you how to do it with his Linux based Audio Appliance.

So what if you don’t want a player like the Squeezebox and prefer to play from your PC? Sure, no problem! Back then you’ll need at least, a good quality soundcard, but nowadays, there are USB DACs to consider. Yup, takes USB data and converts to analog signals.

The Wonderful World of USB DACs
You see, operating systems (at least for Windows and Macs) are smart enough to know that when they detect a USB DAC, all audio signal will be routed through there. Of course, you could control not to do this as well, but unless your soundcard has better sonics, it’s good to consider USB DACs.

USB DACs like Texas Instrument’s PCM2706 (used in My USB Convertor) not only functions as a USB DAC but also as a headphone amp, USB-SPDIF convertor as well as USB-I2S convertor. The last function is the most interesting as once converted to I2S, we could hook up many DAC chips directly. DAC chips like TDA1543, TDA1541… etc. Like this:

If you want to try this yourself with my USB Convertor,

Pinout of I2S on my USB Convertor pin 1 is GND pin 2 is Word Select leave pin 3 blank pin 4 i Bit Clock pin 5 is Data

I guess you know which pins to connect to which pins right? Told you it’s very easy! Power your DAC chip separately though. Don’t be cheap and use the USB’s 5V supply. If you do so, don’t complain if it doesn’t sound good ok?

If you are ooo-laa-laa over sonics of Monica, then this isn’t so simple. Monica’s TDA1545 chip uses EIAJ format instead of I2S. The main difference between both signal formats is the where upon the DATA signal is sent. I2S sends the DATA signal at the beginning of the Word Select signal but EIAJ sends at the end.

No, please don’t ask me why can’t those folks sit down and agree on one format. I have no idea. But look at SPDIF. The very few instances where all folks concerned agreed on a format but it turned out to be a lousy format. Oh well…

Anyway, I tested and built a pure USB Monica, taking in USB signal to I2S then converted to EIAJ then fed to TDA1545. Give us a few more weeks and you can jive with her soon! [USB Monica is ready!]

Squeezing more juice out of the Squeezebox
Back to the Squeezebox. I’m sure many will be wondering how does the Squeezebox compare to audiophile CD players? Well, stock player is nothing to shout about however never ever under-estimate the power of DIY! I’ll share with you 2 mods I tried here.

The very first upgrade every Squeezebox owner should do is to replace the stock power supply adaptor with a beefier unit. One capable of at least 1A (2A is better). Some folks prefer linear supplies while some prefer switching. My preference is switching power supplies but don’t let me influence you. Go try yourself. Just make sure it outputs 5V REGULATED and you’ll be fine. Oh yeah, pay attention to polarity too since we are dealing with DC voltages here.

For the adventurous diyers, the first mod is considered too easy, no fun at all. The second mod, you need to pull out your Torx T10 screwdriver and dismantle the Squeezebox unit.

This is a relatively easy tweak. Easy to understand and easy to implement if you are good with soldering surface mount components. If your soldering skills isn’t up to par, then forget it. Find someone to do this for you. Remember as with all mods, you can kiss your warranty goodbye so if you are not up to it, don’t try to be cheap here. It ain’t worth it brudder.

What we want to do here is modify the SPDIF circuitry. If you trace the digital output RCA socket, you’ll find it ends at pin 6 of chip U15. This is just a 7404 invertor chip. What we have here is that the invertor output goes through a coupling cap then 2 resistors to ground. The resistors form a voltage divider to scale down the output of the invertor from TTL logic level to SPDIF level. If you find all this Greek, don’t worry.

By right, there isn’t a lot of problems with this circuit but due to the very noisy environment of the Squeezebox (what more with a wireless card nearby), we don’t want all the noise to be carried all the way through the digital output (via SPDIF format) to your DAC and the rest of your audio chain. And the easiest way to accomplish this is to use a digital pulse transformer.

The digital pulse transformer accomplishes 4 things.
First it breaks the ground. The SPDIF signal ground is no longer the Squeezebox unit’s ground. This is possible due to usage of transformers.
Secondly, I believe the trans has better driving capability then just a the invertor and voltage divider circuitry.
Third, with a trans, we could benefit from its common mode rejection capability. Meaning, it rejects noise common to both signal and ground. Like in a noisy environment inside the Squeezebox.
Lastly, we could better match the impedance output impedance with the usage of suitable trans.

So first remove L8 and L9. Then desolder the R67 107ohm resistor. One end of R67 goes to ground while the other end is tied to R66. There’s a mistake in above diagram though. Primary (red dot, pin 1-4) has ratio of 1 while secondary (pin 5-8) has ratio of 2. So you should wire pins 5-8 facing the 7404 invertor chip and the other end (pin 1-4) facing output RCA socket. To anchor the trans, I soldered one leg (pin 8) to junction between 107 and 245ohm resistor. Thus pin 5 goes to ground. Pin 1 (red wire) goes to SPDIF output. Pin 4 – SPDIF ground. (If you are fussy, replace 245ohm resistor with 300ohm for even more accurate 75ohm output impedance.)

Now you know why I’m enjoying computer audio?

Moving on to the Software side

The post Computer Audio is Soooooo Much Fun! appeared first on diyparadise.