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Non-oversampling Digital Audio Converter
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Jundac Five - July 2011
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Jundac Five never the TDA1545 sounds so fine...
The Jundac Five is a 16bit non-oversampling digital to analog converter.
It integrates one S/PDIF or AES/EBU input, an optional input clock and stereo fixed analog output.
The DAC chip is Philips TDA1545A; it can operate from 32kHz to 192kHz sampling frequency.
The I/V stage uses discrete, solid state technology, in an open loop (feedback-free) configuration.
A comfortable environment coupled to a particular way to drive IREF pin allows to reach an incredible
quality audio level.
A non oversampling DAC don't use any digital filter. Data coming from CD are directly converted to analog;
there is no coloratura introduced by digital filtering, noise shaping or dithering.
Before output, the signal is smoothed by a sweet first order low pass filter. To reach best listening quality,
it can be coupled to an synchronous or asynchronous low jitter clock.
Power supplies in a DAC are critical to the overall design. The Jundac Five uses six very low noise
separate regulators. These power supplies use polypropylene capacitors and two separated power transformers.
To achieve the full music sonic attributes, we recommend using 200VA to 300VA power transformer
for analog section. This transformer powers the DAC stage and the analog section (I/V converter
and low pass filtering).
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Jundac Five - mounted
- click on the picture to show kit's details
- Assembled and tested
- Sold without transformers
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discontinued
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Recommended transformers
- 1x9V 20VA for digital section
- 2x24V 200VA for DAC and analog
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Technical documentation
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Short technical description
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The Jundac Five use Cirrus CS8416, 32K to 192KHz DIR
(digital interface receiver) chip. The CS8416 provides digital de-emphasis needed for reading some CD
recorded with pre-emphasis.
Before DAC, digital data are re-clocked to avoid digital delay and reduce jitter and noise; re-clocking can be synchronous or asynchronous.
The DAC chip is TDA1545A from Philips allowing 16bit resolution.
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Schematic
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The data stream feed a TDA1545A 16 bit DAC chip followed by feedback
free I/V stage with very sweet low pass filter. The low pass filter is first order filter cutting
at 170KHz using polypropylene film and foil capacitor. The BC550C were chosen for their high quality sounding,
each transistors are matched.
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The IREF pin is the secret of the TDA1545A...
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The incredible audio quality level reach by this kit is due to original way
to manage reference tension pin. This way is different from Philips recommendations.
We develop a reference tension in discrete technology dedicated to this chip.
The TDA1545A reaches unknown dimensions with very large and strong bass,
good definition and fine treble. It changes from all other realizations.
Low noise transistors and high quality capacitors are used to drive this crucial pin:
no electrolytic capacitors.
With this high quality level, this kit has a very good quality price ratio.
It is fine with baroc music, classical, Jazz and POP.
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Low filtered output signal
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Detail
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Dirac impulse response
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