Music Center

You may have noticed I have not updated my site in quite some time now, and those changes were minimal. I have grown a little fed up with all the nit-picking on components etc. Free time is very rare these days due to my work, I just can't bring myself to build anything anymore and tweak it until I weigh an ounce (and that would take a long time ;). A recent listening test has given some surprising results to my ears. From a corner where you would lest expect it and want it to be associated with in the first place: the computer. No, I'm not talking about MP3 or any other form of compressed audio :)

The reason for the particular visit to Bert (who happens to be behind bd-design and the Oris horns and is a good friend) was for something totally different; to try out my new volume controls. After we had finished this test session Bert mentioned he had a USB-to-SPDIF converter in his new TwinDAC. "Want to try it out?", "Sure... beats listening to your stories", "Grmph". Bert had "ripped" a CD onto his hard drive in WAV format using EAC to leach the CD without any errors/error corrections. First we listened to his heavily modified Philips CD880 (CDM1-mk2 transport). Nice, but I was used to this on Bert's system, so it was for reference only. A few minutes later we switched to Bert's PC, running a USB cable straight into his TwinDAC. Novel idea !!!   It didn't take long to hear the difference, amazingly enough in favor of the PC! Less digital, more "ease" and tonally balanced. As if the transport was no longer a factor in the sound. Really amazing the difference this makes looking at the technology behind a PC. 

Looking at it technically you could see why this would bring an improvement. A "normal" CD transport runs it's data synchronously into the DAC; if there is a read error, you will hear it or the error correction equivalent. Not much time to go back and see what it was supposed to be. With the PC and USB2.0 (running at 480Mbs, no longer at 44kHz!) the data parity (or CRC) is regulated by the USB device on the other end. If something is suspect, it is sent again. As the transfer rate of USB and the PC are a factor 100 or greater than your CD transport, the PC almost has all the time in the world to resend any suspect/corrupted data. Another benefit of this system is that jitter is a non-issue, again because of the USB. The only jitter introduced will be between the USB-SPDIF converter and your DAC chip. You can use a 10 meter cable now without any penalties in the form of jitter. USB seems to win out on two fronts here. Almost seems TOO perfect... 

The ears say this is a real improvement, if the technical side is actually right I don't know... but I trust the first over the second.

I have to point out that the music is not being played from the CDROM transport, but the complete track is read from the hard-drive and buffered completely into memory. No moving parts involved at all.

GETTING STARTED

Three or four new problems (or challenges) now arise.  Not the "how to get the data on to your drive". That is easily done with EAC (freeware) and some patience. 

The first problem: Storage

"How do I get 300 CD's on to my computer using my 80GB drive".  Well, in short, you don't :)  On average a music CD contains around 500-600MB of data. Take 300 CD's and you will need a minimum of 180GB free space. Okay... spend eu100 and you will have a brand new 160GB drive. Problem solved, at least for me. You will need some hefty storage space in your PC. "300 CD's, you nuts?!" you may say. Well, this would be problem number two...

Second problem: More storage

As we now have portable hard drives, WiFi and Ethernet networks along with a few audio friends with almost the same taste in music as yourself, you will of course be propagating your music collection (of course by buying the original after hearing it at your friend's place!!! ;). This means your own collection of 200 CDs will soon expand beyond your drive capacity, no matter what kind of drive you may have. It is a good idea to think into the future and reserve an IDE port for an additional hard drive.

Third problem: Noise 

Ever sit next to your PC? I'm sure you have or you wouldn't be reading this :)   Notice the wrrrrrrrrr or bvvvvvvvvvvvvvvvv or fffffffffffffffft ???  Fans everywhere, HF whirring of the hard drive, cdrom making a god-awful noise. All to cool your P4/AMD which are running near the heat limits in order to offer you the fastest speeds available on the market. My juiced up P4-2.4 running at 3.3GHz means I have some hefty cooling issues which will only irritate me if I have this near my audio system. 1 Watt amps would not do it anymore for me :)))

How to solve this? The USB audio setup does not require much of the processor as the amount of data being handled is minimal for modern systems (200kb/s, yawn). I had my "old"  P4/1.5Ghz processor and motherboard tucked away in a closet somewhere until recently. 

1- CPU
A slower CPU means you can use an old mother-board and processor (means cheap to get if you don't have one, about eu150 for a celeron 2.4GHz, Asus board and 256mb of memory). Because these cpu's don't produce a lot of heat, you can do with a smaller or silent cpu fan. One of the noise sources. I had a Zalman 7000CU cooler om my P4, a huge flower of copper cooling fins emitting out from the processor. A 90mm ultra-silent fan blows air over the copper fins and pulls out a lot of heat (even better than most low-end water cooled systems). I reduce the temperature to about about 29 degrees (Celsius) for the CPU while not hearing the fan at all!!! You might even think of going passive cooling if you are not using a 2GHz or higher speed processor (due to heat dissipation).

Zalman cpu cooler, excellent temps and no noise!
Weighing in at almost 900 grams, this is a serious cooler.

2- Power supply
This is the numero uno noise producer in your PC if you have not done anything to reduce noise so far. Tackle this obstacle and you will get rid of about half the noise pollution. I opted for the Zalman 300W supply that was still in my case from the previous system. This supply regulates it's own, already ultra-silent, fan depending on the temperature of the supply. Noise level is around 20dB over ambient (pindrop) noise. You really can't hear this thing, as any noise that does come out of them is dampened by your case or is directed out through the back of the PC.

3- Case fans
Most PCs you buy at the local PC dump/store will only have one extra fan to get rid of the hot air inside the case itself. These are the standard eu2.00 black types that whirrrr at a just tolerable level. My case has four fans, I like a cool system (OC rulez). Two fans suck air in from the front and over the hard drives, increasing life expectancy quite a bit. Then there is one fan in the back near the CPU and one at the top of the case that both suck out the hot air. These four combined give a nice airflow through my case. The fans I use are the Sharkoon SL3; these are ultra quiet fans running at around 18dB at max speed, and as low as 15dB as lowest speed (which I use). You can't hear these things unless you press your ear against one (this could hurt, let me warn you!!).

SL3 ultra-silent fan

4- Hard drives
Sometimes overlooked... The 7200+ rpm drives can produce quite a bit of high frequency noise, even though they use "noise reducing technology". Put two or three drives in there and your fans won't be the problem anymore. I had one of the first generation 7200rpm 40GB Maxtors along with a new 160GB 7200rpm Maxtor. After replacing the fans etc, the HD could be heard from about 5 meters away (just idle, not even seeking). I thought not much could be done about this until unplugged the 40GB drive. The 160GB Maxtor I had in there was almost inaudible compared to the 40GB cousin. Wow... This made me look further into a drive that made almost no noise at all. A week later I received two Samsung SpinPoint drives; 160GB 5400rpm versions. I deliberately took the slower version as they make about 2-3dB less noise than the 7200rpm versions. As speed will not be an issue while playing music (15MB/s or 25MB/s is a non-issue for cd playback; a normal transport only does 150kb/s anyway :).

To get rid of any seek-noise (the drive heads going from one place to another, the chirping/clicking sound you sometimes hear along with the HDD led that lights up) I also bought two Sharkoon "vibration absorbers". This is just a fancy name for a 5.25" drive bay with a bunch of rubber o-rings that suspend the drive; and a lot short too. They will absorb the shaking of the drive, instead of this being transferred into the case and increasing the noise. Sounds familiar... nah...

Samsung suspended in o-rings to absorb vibrations

The Samsung mounted into the PC case
To the left is the cover for the drive bay.

The result was totally amazing... I actually checked twice to see if I did not connect anything the wrong way as I could not hear the drive spin up while booting. It's THAT quiet !!!!  Built into the absorbers and mounted into the cabinet, I can't even hear the seek noise now. Lovely and quite a contrast to the 10.000rpm drive in my main system (WD Raptor).

Fourth problem: mains contamination

This is the reason we don't want appliances and computers on the same mains group as our audio system. The PC power supply is a switch mode unit. Some have actually done something about injecting too much HF back into the mains lines. Some don't know the meaning of the word.

I am still looking into this... As my ears already tell me there is an improvement between the PC and my transports (Philips CD880, MicroMega F1, MicroMega Duo 3.1), I think an added mains filter will bring even more improvement.