Let me put my 2 cents on the available tube replacement candidates for our Tube Magic and Tube Magic D1 DAC.

The DAC uses a Chinese made NOS 6N3 tube, which is a clone for western 5670 tube. There were quite a few factories manufacturing 5670 tubes in the past. Even for the same factory, there have been different versions. For example, GE, Sylvania, Raytheon, WE (Western Electric) they all made 5670 tubes.

It is believed western made 5670 has better sound quality than the Chinese/Russian clones.

For a start, you can try GE and Sylvania JAN (Military) version 5670 tube. They are widely available and reasonable priced. I believe most our customers replacing the stock tube with GE/Sylvania JAN tube. You can expect a certain degree enhancement on sound quality.

GE 5 stars 5670 tube

GE 5670 JAN tube

For better performance, you can try WE396A or Raytheon windmill getter, they are more expensive than above 2 models. The WE396A is probably the best one, but it is also the most expensive tube ( ~ $40 per tube).

Raytheon Windmill Getter 5670 tube

There is also Russian 6N3P-I, a 5670 clone made for Russia military. I’ve never tried this tube and don’t know if it is any better than the Chinese tube used in our DAC. The Chinese tube comes with the DAC was manufactured by Beijing Tube factory in the 70’s for Chinese military.

The only complain I have, is the sound quality from the two channel analog outputs in the Squeezebox classic and duet, it left much to be desired.

My vintage Sansui AU-D707F stereo amplifier and Squeezbox

My setup is quite simple, a 2 channel stereo amplifier to a pair of 200W louder speakers.   The squeezebox is connected via analog connections. Although squeezebox claimed to use high-end 24bit DAC and special designed circuit, the analog outputs still sound relatively weak: it just doesn’t have the clarity and strength as my old sound source, an aged Marantz CD Player. So my pursuit to better sound begins.

My hand made linear power supply

The first thing comes to my mind is the power supply. Squeezebox comes with a cheap, small switching power supply. You know how bad the switching power supply will do to the sound quality, no matter how hard you try to regulate it (as squeezebox claimed), the electrical noise & ripple will still be there. On the contrast, Linear power supply can be up to 10,000 times quieter than switching power supply.

Notice the electrical ripple difference

I ordered a 5V linear power supply and replaced the old cheap switching power supply. It did improve the “strength” of the audio signal, the bass is much more powerful now. However, the sound is still lack of clarify and depth.

Naturally, the next step for me is to utilize the digital audio output on the Squeezebox — I don’t want Squeezebox to handle the “digital to analog converting” job, I want something else. Since most stereo amplifier doesn’t come with digital audio connection, the only possible solution will be a good quality standalone Digital to Analog Converter, in my case, the Maverick Audio Tube Magic Upsampling DAC ( What else can I choose? It’s my company’s own product ).  After I hooked the DAC into my setup, I immediately found the clarity of the sound has improved a lot, I can hear a lot more details than before.  The overall sound quality is more transparent, natural and with better bass/tremble.  It is really close to the sound when I was using my old school CD player, I can hardly to differentiate the difference between my old CD player and FLAC music played from Squeezebox.  I can say the result is very pleasant, I can finally let go my old CD player without missing the sound quality.

But wait; isn’t DAC already included in the audio devices? Why do I need a standalone DAC?

Answer is simple, standalone DAC offers the easiest and probably the cheapest way to upgrade your music listening experience.

CS4382 DAC on Sound Blaster X-Fi Fatal1ty

Why? Because the “build-in” DAC in most audio devices are not good enough.  Let’s take computer sound card for an example:  the cost of the DAC in 99% sound card is less $1. For $1, how good can the digital to analog conversion be? Not to mention the “noisy” power supply in the computer, the signal interference, the “non-audio grade” components and etc.  As the result, the audio output on computer is noisy, lack of clarity and not very transparent.

Same thing happened to most of other audio devices: DVD player, Blu-ray player, network media player and laptops.

We are all too focused on the “digital” specifications, and forgot the “digital-to-analog converting” part is as important as the digital part, and the DAC is the key element  to the sound quality. A properly designed external DAC will greatly enhance your music listening experience, it is not an assumption, it is a fact.