Adding TentLabs XO2.2 low jitter clock to exposure 2010S CD player

I added a TentLabs XO2.2 low jitter clock and a separate power supply for it to my Exposure 2010S CD player. The process was very straightforward - see the pictures.

The Exposure 2010S CD player has an easy internal layout, where most of the components sit on a large PCB.

The original clock is based on the 74HC04N chip located in the middle of the PCB, to the left from the three white power connectors connecting the toroidal transformer. A close-up picture shows the crystal resonator wrapped in a black heat-shrink tube, two 33pF capacitors on each side of the resonator (those with black dots on top), and a resistor R75, which also serves in the circuit. The oscillator is built on the single invertor (pins 13 and 12 of the IC).

The original clock is generating 16.9344 MHz at 5V CMOS levels.

To install XO2.2, I removed the resonator and the capacitors, leaving the resistor in place. I connected the signal cable from XO2.2 to the pads of the capacitor that is closer to the pin 14 of the IC; of the two 33pF capacitors, it is the farthest from the front of the CD player. Then I glued the XO and the power supply boards to the right of the main board, closer to the front panel. I could probably drill the bottom plate and use screws, but I didn't.

The power supply is connected to the mains switch with two wires (red on my photo) that go along the front panel near the bottom and are soldered to the small PCB holding the on/off switch on the left side of the panel.

That's it! It took me maybe two hours altogether.

My impression is that with the XO, the sound became richer in details and more transparent, with better spatial resolution. Obviously, this is very subjective; no double-blind comparison could be performed on just one CD player being modified.

P.S. I also had to replace the "analogue output" double PCB mounted RCA connector, as its ground pin broke. I installed two panel mounter RCAs, seen in the photo.

CD transport

A CD transport with a Philips CD Pro 2LF mechanism purchased from Enco - they still have it available! Built in 2011 from a Chinese kit with the enclosure matching the DAC from the previous post. As in the DAC, extra thick copper and machined aluminum do not add up to great performance. Nice remote, though.

Hifidiy.net DAC

Built from a kit in 2011.

The design is a typical oversampling DAC of the era: S/PDIF receiver is followed by an asynchronous sample rate converter, followed by a PCM1794 DAC - quite similar to my ezDAC (see an earlier post). The USB interface is built around TI's PCM270x chip. A fancy addition is a tube buffer. The construction is very solid with thick aluminum panels.

I know this is subjective, but I don't like the sound at all. Unfortunately, I can say this about every single eBay kit or PCB I have ever purchased. They all feature pretty PCBs with extra thick copper, machined aluminum panels and, in this case, an R-core power transformer, they promise big ticket performance on the cheap, but they do not deliver. The good sound is not in thick copper or solid aluminum enclosure.

Digital Audio Signal Generator

This handy instrument is a version of the design published in the Australian Silicon Chip magazine (a subscription is required to view the details of the article).

It is based on a dsPIC33 microcontroller, has TOSLINK and S/PDIF digital outputs (44.1k, 48k and 96k sample rates) and a stereo analog output. Output frequency, phase, attenuation, and other parameters are set by the keyboard. It produces sine, square, triangle, and sawtooth waves and has a variety of modes. It can be powered by an external DC source or a battery. The article claims low distortion for sinewave (less than 0.06%) and even lower with a good external DAC, but I did not verify that.

Highly recommended.

BantamDAC

ezDAC (see my previous post) lacked an USB input, so I leveraged my newly acquired SMD soldering skills building BantamDAC from a kit. The DAC ended up inside my version of Pete Millett's low-voltage hybrid headphone amp, to be posted separately.

Jason Stoddard of Schiit Audio wrote: "[R]emember, this is early 2011 we’re talking about. Adaptive USB 1.1 was kinda the de facto “good solution”, with most audio components using the truly terrifying TI USB input receiver/DAC/headphone amplifier/car washer chips that weren’t even adaptive. "

Yes, BantamDAC uses one of those TI USB input receiver/DAC/headphone amplifier chips. The choice of the chip puts limits the DAC to USB Audio Class 1 up to 16bit/48kHz. It was ok for 2010; today I'd look for a higher fidelity solution though. 

ezDAC

In 2010, having built power amps, speakers and a preamp I wanted to try my hand in digital sources and built a version of ezDAC, (pronounced 'easy-DAC'), a nice do-it-yourself 24bit/96kHz upsampling audio D/A converter, designed by Evan from ezDIYaudio.com (the site is now something else, unfortunately). It is a fairly simple DAC with a CS8416 digital receiver, an AD1896 sampling rate converter, and a PCM1794A with a passive I/V converter for the DAC proper. Nothing fancy.

If was a first for me in many ways, including my first digital audio product I built from scratch, my first use of Eagle to re-create ezDAC's PCB, and my first SMD soldering experience. As Nelson Pass said, the water is fine.

I used three separate 3VA toroidal transformers (for digital circuits, the DAC, and opamps) in the PSU. The enclosure is from modushop.

Eagle files for the PCB are available.