the search for CD playback tranquility

This post accompanies my blog post discussing Herb Reichert’s article The Search for Audio Tranquility (linked also there). I recommend you read those first. Understanding what Herb was aiming for is crucial to understanding what follows here.

I’ll will start where Herb stopped: ‘CD? You-pick-em! Trying to buy a separate transport, cable and DAC from three different manufacturers seems unmanageable and a sure-fire formula for turning up the voices.’

So let’s say you want to ‘quit’ the audio hobby and listen to music; to chill out and enjoy your CDs. All you want is some simple audio peace. Then you have come to the right place; this post is for you.

However, if you are not ready for music, or audio peace, then I am pretty sure you will find this post contentious, aggravating, even downright daft. Not to worry, you can discuss it with your audio committee and you don’t need to let me know in the comments.

First things first: CD playback in 2015? Well yes. Surveying the last decades, the following three approaches have proven themselves for digital playback:

1. CDs. Yes, they just won’t die. It is basically the only digital disk game in town, if you are in it for the music. ‘Everything’ gets released on CD, it’s the default. The committee in your head may fret about low resolution, but the hi-res disk formats simply went nowhere.
2. Streaming, from computers at home, or straight over the internet. Compared to CD, you sometimes can obtain higher resolution, or underground releases that do not make it to disk. If the library management software is well designed (slim chance, but it can be done, just ask me) then the discovery of music, and the listening session, can reach to a whole new level. On the other hand, the tea ceremony of playing disks is gone. People I know have build systems around this approach and I respect their choice.
3. Just don’t; go back to vinyl. Yep, it rocks. Plenty of vintage disks and ever more new stuff is also released on vinyl these days. Full tea ceremony included. Plenty of people I know have build systems around this approach and I respect their choice.

In short, the essence of digital disc playback is to forget about either digital or discs, or to settle for CD.

This all is my (humble) opinion, so there is no need to start a polemic about this triumvirate. As stated I will concentrate on approach no.1, and that’s because it is there that I can offer some peace. Here are the four simple steps to get there.

First, I am going to solve Herb’s ‘transport, cable and DAC’ problem by insisting that you concentrate on one-box players. There is a solid technical reason for this: S/PDIF. Getting two information streams—data and exact conversion timing—through one wire was never going to work, as physicists and information theorists could have confirmed from the beginning. And it never did.

The folks at Naim have been right all the time: you stick all the digital bits, oscillator and DAC chip included, in a single box; close together, with always the right number of pcb tracks between them. And if you really want to geek out, then you put some real stout raw power supplies in an external box and use them to supply the sensitive parts in the player.

Second, we are going to make use of the fact that over the last 30 years, one classic component in CD playback did emerge: the TDA1541 DAC chip. This is not just my opinion, but confirmed by exactly the kind of indicators that Herb wanted us to check: there is a cult around this chip and CD players using this chip demand a premium in the second-hand market. Significantly, spare chips have disappeared from the market; they are now in the clutches of small-time high-end manufacturers and chichi audio parts dealers. Somehow, this all reminds me of Western Electric 300Bs.

To summarise step 1 and 2: you want to get your hands on a one-box cd player with a TDA1541 DAC chip.

Luckily, that means loads of machines, because for certain generations of CD players, lower-middle class and up, the TDA1541 chipset was the logical choice. There are lists around the net with all TDA1541 machines ever build. You can find anything, from that ten-€/$/£, flea-market score, to players with the right name and/or tank-like build quality that have retained their value over time. Simply obtain a machine that matches your budget and ego.

It gives me great pleasure to illustrate this post with the modest philips CD 207—indeed, a TDA1541 player. If this gives you the hots for a red CD player, instead of a mega-buck machine, than that’s cool with me (btw: top-loading machines have a certain tea-ceremony quality).

Step 3 and 4 towards audio peace are two simple mods that will wring a lot more music out of your TDA1541 CD player.

The first mod is to convert your player to non-oversampling. This usually involves cutting a few traces and soldering 3 or 4 pieces of wire. There are plenty of instructions for this mod around the net. Before you buy a player, check which digital filter chip is inside. Then check the availability of non-oversampling mod instructions for this chip.

The second mod is the ‘direct out mod’; bypassing the regular filter and output stage—which usually includes a pair of electrolytic coupling caps—by connecting a right-sized cap from the output of the I/V converter (first op amp after the TDA1541) directly to output connectors (the RCAs). Cut the connection between the I/V stage output and the input of the stage that follows it, ground the latter so that it can’t do anything funny. Ah, and also make sure that the signal pins of the output connectors are not connected to the original circuit anymore.

Right-size the caps for the input impedance of your (pre)amp. Do not forget about pull-down resistors between the cap output and ground. Example: 100kOhm (pre)amp input impedance, let’s use 10x larger pull-downs (1Meg), in parallel that is 91kOhm. Using 5Hz for the cap high-pass, that makes 1 / (2π × 5 × 91k) = 350nF. 330nF is the nearest standard size; pick some nice caps—oh, the voices in your head are multiplying—and done.

And that is it. It is what Herb wanted to achieve. A classic CD player, ‘not modified too much’, that will serve up the music on your CDs for as long as the CD transport mechanism holds out (take good care of it, and get a spare).

I am sure plenty of you disagree with some of my choices; insist we check out the latest XYZ DAC chip, or think the mods should go much further. I know what that feels like. However, going there is a sure-fire way to wake the committee of audiophile voices. The point of this post is music and audio peace, and here you got it.

—peace out

ps: want to go a liiiiittle bit further with the mods? I know what that feels like. Really, the only bottleneck left is the I/V converter. Replace is with a simple design (~5 parts) that does not employ feedback. Ah, and remember what the expensive wino Naim said…