R2R DISCRETE

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R2R DISCRETE
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The PCM DAC (pulse code modulation) is a DAC able to decode multibit binary numbers into musical analog waveform. PCM is basically the digital music as we know it. MP3 is PCM, CD is PCM, so called RED BOOK is also PCM. Flac is PCM as well as AIFF, WAV, Ape etc. All iTunes is PCM. DVD audio content and Blu-Rau audio is PCM. Also Spotify and Tidal are both PCM. Only DSD and Super Audio aren’t PCM. Having said that, the R2R converter also does DSD up to 256 and does it seamlessly with autosensing (so you can play mixed pcm/dsd playlists).

It is fully compatible with Roon, HQPlayer, and with all softwares like JRiver, Foobar, Audirvana, JPlay, Daphile, Squeezebox, ETC. It is also fully compatible with the Sound Galleries Monaco server.


The oldest known method of converting the binary pulse code to analog is by means of so called resistor ladder network, where every possible digital number (binary), representing decimal signal values between zero and 65535 is represented by a resistor pair with corresponding resistance ratio. When a decimal value - say 16 enters the machine, a resistor Rx is connected to a fixed voltage source and we read the value (16) at the output. Next number may be for example 45 - and again - a resistor pair divides the voltage in such way that analog voltage “45” is produced. And this happens 44 thousand times per second per channel. And we need lots of resistor pairs.

Originally in the 40’s and 50,s the old DAC machines crunched the numbers by means of tube relays and actual resistors. Then in the 60’s tubes were replaced by transistors, to be obsoleted by chips in the late 70’s. And circa around 1980 the mother of all musical PCM DAC chips - Philips TDA1540 was born and remains practically unbeaten until today. The only reason it is not the current KING of all DACs and chips, is that it was created as 14 bit unit, not 16 or even better - 24.


The TDA chip is nothing but a ladder of several hundred resistors built in the form of integrated circuit (silicon chip) and hence miniaturized to a reasonable size, usable in home electronics. This type of DAC chips is called multibit or R2R. (resistor to resistor)


When in 90’s these R2R chips became extinct and replaced by cheaper, easier to make, better measuring DELTA SIGMA chips - in some die hard audiophile circles the cult of old conservatively made R2R was created. People realised that a properly implemented R2R sounds better than delta sigma. This “digital amish” group probably represented around 5% of all audiophiles, often overlapping with the vinyl fanclub. They carried the torch through the turbulent last two decades.


The absolute peak of R2R was the chip from Burr Brown (Japan) (later acquired by Texas) called PCM1704, with close followers of Philips’ TDA1541A, (and 1547) Analog Devices AD1865 and the Burr Brown’s own PCM 63. These chips are considered the pinnacle of the PCM era and were all discontinued about 20 years ago.


In very recent history we have witnessed the efforts to resurrect the R2R technology albeit without the actual chip. This required rebuilding the R2R ladder from the 40’s but with the use of infinitely more precise and closely matched SMD resistors which have unbelievable tolerance of 0,01%, which is roughly 2000 times better than by using older carbon resistors. This R2R ladder to be of any practical use however, requires a microprocessor (called FPGA) able to manage inflow of data and precise switching, not to mention conversions from every possible clock frequency and bit depth. FPGA is a kind of orchestra conductor where R2R pairs are musicians. This type of DAC is called R2R DISCRETE and you can tell it when you see hundreds of miniature resistors soldered side by side in straight rows. It kind of looks like London in Google Earth.


Currently only world strict elite of 5-6 companies uses R2R discrete ladders, and only in their flagship players. Lampizator was (probably) the first company to market R2R in conjunction with tubes in general, and surely the first to offer DHT tubes with R2R. Such exotic combination is a match made in heaven. It has synergy unheard of before. The modern FPGA programming and superb military components allowed us to create a DAC that beats all nostalgic chips mentioned above, this is just another league. Our design has nothing to do with nostalgia, old romance, sugar coating or rosy colouring. This is the most revealing, most precise, most accurate and most musical way of conversion humanly possible.


Five factors of paramount importance have met inside our R2R DAC that make it so unique, that allowed our sub 20K Golden Gate to make a serious earthquake in the 50K dollar DAC circles:

  1. -Discrete R2R technology of the highest achievable quality

  2. -Direct DC coupling to triode grids, without any caps, resistors or transistors, op-amps or opto-isolators or glue logic 74 series gates

  3. -Use of directly heated triode power tubes (the cleanest sounding tubes in the world)

  4. -Use of the finest capacitors in the world after the tubes - namely Mundorf, Jupiter and Duelund

  5. -Simplicity unmatched by any other DAC in the world: the musical signal, between the last resistor of the ladder and the RCA output goes only through two (TWO!) components - one active (triode) and one passive - output capacitor. This is the lowest parts count in the whole DAC kingdom ever achieved commercially. Of course our designs are zero feedback and zero compression.


THE LATEST NEWS: As of July 2016 the newest Atlantic DAC does R2R conversion (with DSD added) with directly heated pentodes/triodes. making the most amazing product of it’s kind