Some recent listening test have 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 my visit to Bert (who happens to be behind
bd-design and the
Oris horns) 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 DAC. "Want to try it out?",
"Sure... beats listening to your stories", "Grmph". Bert had
ripped a CD onto his harddrive 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 DAC. Novel idea !!! It didn't take long to hear the
difference, amazingly enough in favor of the PC! Less digital (rough), 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
technologie 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...
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
The first problem: Storage
"How do I get 400-500 CD's on to my computer using my 80GB
drive". Well, in short, you don't :) On average a music CD
contains between 400-500MB of data. Take 400 CD's and you will need 180-200GB of
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.
" 400 CD's, you nuts?!" you may say. Well, this would be problem
Second problem: More storage
As we now have portable hard drives, wifi and ethernet networks plus a few audio
friends with almost the same taste as yourself, you will ofcourse be propogating
your music collection (of course by buying the original after hearing it at your
friend's place!!! ;). This means your own 200 CD collcetion will soon expand
beyond your drive capacity, no matter what kind of drive you may have.
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. To cool your juiced up P4 which are running near the
heat limits in order to offer you the fastest speeds available so far. My juiced
up P4-2.4 running at 3.4GHz 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 (200kb/s, yawn) for modern
systems. I had my "old" P4/1.5Ghz processor and motherboard
tucked away in a closet somewhere until recently.
The 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). Beacuse 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 have a Zalman
7000, a huge flower of copper cooling fins/fans 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 water cooled systems). I reduce about 25 degrees
(Celsius) from the CPU while not hearing the fan at all!!! My beefed up CPU runs
37 degrees nominally while doing near 60 degrees with a standard fan. The 1.5
won't be pushed, so I meant o say the cooling will be more than sufficient and
there will be no noise coming from this cooler.
2- Power supply
This is the numero uno noise producer in your PC. Tackle this obstacle and you
will get rid of about half the noise polution. 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. 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
3- Case fans
Most PCs you by 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 as it has
forseen the 7200rpm drives that get pretty hot. 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 19dB 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 (it still hurts,
let me tell you!!!).
4- Hard drives
Sometimes overlooked... The 7200rpm drives can produce quite a bit of whirring
noise, even though they use "noise reducing technology". Put two or
three drives in there and your fans won't be the problem anymore. Not much can
be done about this really, maybe add some rubber grommets or encase the drive.
This last solution will bring up temperature, not a good thing.
Fourth problem: mains contamination
In all my system is almost inaudible. Dead-quiet compared to standard PC's.
Good enough to use near my system.
I had a nice Lian-Li aluminium
case left over from my current PC which outgrew it's case.