Basic Digital Electronics
4 stars based on
49 reviews
Of course, these are not the only important design factors; two others that come to mind fairly quickly are power supply and time-base jitter. Over the years, my search for analog-like sound from digital sources has proven to r 2r ladder dac 4 bit ripple a frustrating quest.
The low point was the advent of the single-bit delta-sigma DAC and its adoption by many mainstream manufacturers—an event which, in my estimation, plunged digital audio into a Dark Age for several years, until decent multi-bit delta-sigma DACs emerged. The PCM employs a sign-magnitude architecture in which two DACs are combined in a complementary arrangement, sharing a common reference and a common R2R ladder r 2r ladder dac 4 bit ripple bit current sources.
R 2r ladder dac 4 bit ripple resistors are laser trimmed at the factory to achieve an accurate match between the two DACs. The result is exceptionally linear and low-harmonic-distortion output. Sadly, Texas Instruments has put the PCM on end-of-life status probably due to cost of manufacture and dwindling demand, so I would not be surprised to see it discontinued by the end of The key factor in the application of the Philips TDA-series chips is turning off the companion digital filter.
From an engineering standpoint, oversampling the datastream to push ultrasonic image spectra further away from the audio bandwidth followed by a digital filter makes perfect sense. One is tube buffered, while the other is buffered by r 2r ladder dac 4 bit ripple Analog Devices AD video op-amp. A third-order analog low-pass filter rolls off the image r 2r ladder dac 4 bit ripple at the input to the tube buffer. However, the image filter is omitted for the solid-state buffer. Poon explains that there were several considerations involved in this decision.
Aside from space and cost limitations, he does not consider the image filter to be an essential part of the circuit, as most users simply use the tube output and forget about the solid-state output. Technically speaking, the main reason for attenuating the ultrasonic image spectra is in order to protect downstream components, e. It includes a volume pot and a line-level gain stage, comprising yet another dual-triode configured as an SRPP.
A switch on the front panel allows the internal connection of either the tube DAC output or the line-level input to the linestage. However, I suspect that many of you would be interested in using the r 2r ladder dac 4 bit ripple as a standalone DAC by connecting the tube DAC output to an external preamp.
That was my preferred connection scheme. The linestage output impedance is ohms, so any headphones with that sort of input impedance should be compatible. The operating instructions specifically mention the Sennheiser HD ohms as well as the Beyerdynamic DT ohms. OK, so these are not the most transparent cans on the market, but they sounded way better than they have in many years.
This seemed to me to be the next best thing to a battery supply, so I tried it and liked it a lot. Precision voltage and frequency selections can be dialed in on the front panel. Line frequency selections are 50, 60,and Hz. Two outlets are provided on the rear panel that can accommodate a combined power draw of watts. You might legitimately ask, why use such a frequency as high as Hz? Well, operating a power supply at higher frequencies does improve its efficiency and reduces residual AC ripple in the filter circuit.
Aircraft power supplies operate at Hz for this reason. I wondered if r 2r ladder dac 4 bit ripple rectifier diodes would squawk about being switched on and off at higher frequency than 60Hz. It turns out that even a garden-variety rectifier diode has a settling time of about 30 microseconds, which means that it would be comfortable at Hz and even higher line frequencies. It is surprising that even with its massive twin toroidal power transformers and plenty of voltage regulation that the NM24 would benefit from clean re-constituted AC.
In particular, the sonic effect of switching from a setting of 60 to Hz was quite audible and could be best described as a smoother, more relaxed presentation, as if harmonic textures were cleansed of a layer of electronic hash.
Image focus was superior as well. It is helpful to contrast the NM24 with a similarly priced, popular commercial DAC that sits at the opposite end of the tonal spectrum.
To my ears, the Oppo had sounded slightly bright through the upper midrange, which emphasizes low-level detail and at the same time projects female vocals a bit forward.
An appropriate analogy that comes to mind is that of a moving-magnet vs. The NM24 sounded much like a good mm.
