Build a computer audio transport

How To

Build a computer audio transport

Scott Berry of CAD (Computer Audio Design) describes how to build a digital transport out of a computer and shares his tips getting started in computer audio.

 

 

The biggest issue in computer audio is the perceived complexity. One of the things I am trying to show people is that this does not need to be the case. We recently won the ‘Best Sounding Hi-Fi Room’ award at the Bristol Sound & Vision Show in which I purposely used a reasonably priced laptop (along with the 1543 DAC of course!).  This was a Windows 7 laptop with a third generation i7 processor that cost £450. The only hardware modification I did was replacing the hard drive with an 120GB SSD. I put all music files on a standard external USB3.0 hard drive (not SSD) and used a low cost linear power supply (Kingrex) to power the external hard drive. I also disabled some of the software that was not required for audio. A description of exactly what I did is on the Computer Audio Design website. For most people if you purchase a computer similar to above and follow the simple ‘Windows Audio Playback Software’ instructions you will have what I feel is an excellent computer transport. But as with all things in audio you can do more if you desire.
For those of you that do not wish to set-up your own computer for audio or want even better sound quality there are companies offering computers designed for audio such as Item Audio and MCRU with their Music Server. These can offer additional hardware and software modifications and improve the sound quality even further.

CD Ripping
Very simple, use dBpoweramp. I have tried everything and in my opinion it is easy to use, gives great rips and is cheap. The batch mode can save you a massive amount of time.
dBpoweramp is also extremely useful for changing the format of your entire music collection form one format to another using the "Batch Converter". You can also change the bit rate using what is known as "dither" and upsampled or downsample your music. Highly recommended.

Music Format
Disk Storage is very inexpensive today. There is no reason to listen to your music even in a losslessly compressed format such as FLAC. FLAC is similar to a Windows ZIP file. The music is compressed but you can uncompress it and no data is lost. That is great, but we want the computer doing as little as possible while playing music. The computer has to do more processing or "work" playing a FLAC than it does with an AIFF or WAV. I can hear a difference between FLAC and WAV or AIFF. I cannot hear a difference between AIFF and WAV. AIFF is basically the same as WAV but has built in metadata storage. You can get metadata storage to work with WAV, but AIFF is just easier. For that reason I recommend AIFF.

Playback software
You must use high quality playback software. If you are in the Apple world and already used to iTunes you have many excellent choices of playback software to choose from such as Audirvana, BitPerfect or Pure Music (not forgetting my favourite, Decibel, Ed). These software packages integrate with iTunes, can be set-up once and will run in the background. They’re very simple and really improve the sound quality. If you are in the Windows world your choices for playback software are a bit more limited. At the moment JPlay audio playback software along with JRiver and JRemote on an iPad is a great combination.

 

 

Hard Drive Technology
If your current operating system hard drive uses a standard spindle HDD, then replacing it with a SATAIII Solid State Drive will improve the sound quality. Unfortunately this is a reasonably difficult procedure and is beyond what many people would be willing to do. But if you are up for it you will find a big sound quality improvement! I feel this is due to the read rates of SATAIII SSDs being so much higher than any HDD. My current favourite is the Intel 520 series. Since this drive is only for your operating system and playback software and not for storing your music collection a 120GB is plenty big enough.
Never store your music on the same drive as your operating system. Your OS drive is continually being accessed by the operating system. If you put your music collection on the same drive then your computer will be accessing the drive for two key processes simultaneously and I believe that sound quality suffers as a result.
Does SSD for music storage sound better than standard spindle hard drives? The simple answer is yes. If cost is no object go for it. But until just very recently the cost versus sound quality gain did not make sense to me. You can now get 250GB SSD for about £150 in the UK. At that price point it is just starting to make sense.
If you are using a 7200rpm HDD for your music collection storage here is a tip that will cost you next to nothing and will improve sound quality quite a bit. Place your hard drive on a hard surface like glass or stone and listen to your favourite track. Now find something soft, like a new sponge or even a pile of clothes. Place the hard drive on that and listen again. A HDD that is spinning around at 7200 rpm is like a turntable. It will vibrate. Trying to reduce or absorb that vibration improves sound quality.

Interface to external drive
If you are using a USB DAC it is generally best to not use a USB connected hard drive for your music collection. It is best to try to limit the activity on the USB bus to only your DAC. I have found that many of the laptops now days have both a USB2.0 and USB3.0 connections. In that case you can sometimes use the USB2.0 for your DAC and the USB3.0 for your external hard drive and they will be on different controllers, but unfortunately not always...
Or get a computer with an eStata, Firewire 800 or Thunderbolt connection along with a USB connection and use one of those for your external hard drive connections.

Laptop versus desktop?
Laptops have to cram as much stuff into a small space as possible. Because of that I feel a desktop arrangement is the best. It is also easier to modify and upgrade a desktop than a laptop. That is not to say you cannot get good sound quality from a laptop. I use laptops for demonstration work when I am travelling and am more than please with the sound quality I get.
I personally use an iPad for controlling my computer so I typically don't have a keyboard or monitor if using a desktop and keep the lid closed if using a laptop.
Many people feel you can get by with a low powered CPU and not much memory for an audio PC. I disagree. My recommendation is to try to get the latest Ivy Bridge i5 or i7 quad core CPU and 8GB of reasonably high speed / low latency RAM. If you are using a 32bit Operating System then there is no reason to get more than 4GB because that is all your computer can access. Generally as the speed of RAM increases the latency decreases. High speed RAM that has low latency will cost quite a bit more than high speed RAM with higher latency.

DC Power Supplies
Most external drives use some type of power supply. The ones that come with hard drives are low cost ‘switch mode’ wall mount power supplies. The wall adapter will be labeled with the output voltage and current. Try to find a ‘linear’ power supply with the same output voltage and at least as much current. The voltage needs to be exactly the same but the current output can be equal or greater. Switch mode power supplies have much more noise in the higher frequencies than linear power supplies.
There are companies now offering linear power supplies to replace the switch mode power supplies that come with small desktops and laptops. There is a great deal of discussion on the forums about this due to the fact that all motherboards use switch mode technology in them. The main questions being: "Why would a linear power supply make a difference if the motherboard is then using switch mode technology?" My limited experiencein this area has led me to believe that it is a very positive upgrade, and I am currently doing more research in this area.

Store your music in the root directory:
This one may seem a bit farfetched but I have played around with this enough that I think it does make a difference. What I mean by this is instead of storing your music like this:

E:/Scott/My Music/Jim White/Jim White - Transnormal Skiperoo/...

Store it at least like this:
E:/ Jim White/Jim White - Transnormal Skiperoo/....

Or like this:
E:/Jim White - Transnormal Skiperoo/....

This is still not the "root directory", you could actually just put all your individual songs directly in E:/ - but that is even a bit much for me! If your metadata is correct and you are using software such as JRiver it will not matter at all.

 

Scott makes one of the very best USB DACs on the market in the CAD 1543. Once you have a top notch computer transport I recommend that you hook it up to the 1543, it’s a bit of a game changer.

 

Comments

Those who may not be willing or able to convert their computers in such a fundamentalfashion may wish to take a simpler avenue by converting an old laptop and follow some very simple steps. 1. Chose a computer or a laptop with at least 2Mb ramand a processor exceeding 1.5Mhz.2. remove all programs and content from the Hard drive.3. Choose a media player softwareof your choice.4. Digitally connect your computer to an affordable external DAC to eliminate hum and fan noise beingamplified through your hifi.5. Use a free app on your phone to control the transport functions from your phone.The quality of the presentation will still be able to give most conventional CDs retailing for £750-£1000 a very serious scare.Lastly, Those who may not wish to have a computer in their living room may wish to examine the possibility of a media player/streamer instead. The streamer set up offers superior ergonomics as it does away for the need for a separate DAC, it can also connect wirelessly to a home network, thus eliminating the need to run cables from adjacent rooms the process.In closing I need to stress that none of the "affordable" solutions will offer the same level that the very eloquent and specialized solution mentioned in the article be able to offer.