You listen to recordings all day- music on your phone, dialog on television, radio in your car, etc. With rare exception, these are digital recordings converted to an analog signal played over speakers or through your headphones. Every sound you’re hearing has been processed through a DAC, and all of those DACs are one classification of DAC called “delta sigma”.
The Delta Sigma DAC was a brilliant invention because it doesn’t require many parts (making it cheap to manufacture), and it is easy to fit into circuit designs where Digital to Analog conversion is a necessity (but not the focus).
This type of DAC, which colors every recording you hear, is based on a process that simplifies the signal (losing some of the detail) and then rebuilds the signal (restoring detail). Similar to freeze dried food however, the reconstituted sound isn’t exactly the same. Delta Sigma DACs change the format of the signal and create extra noise during processing which is then filtered out, you don’t get the recording exactly as it was.
A second type of DAC exists, R-2R, a fundamentally different approach to digital to analog conversion. Instead of simplifying and reconstituting, this DAC maintains the detail of the recording throughout the process, at the expense of parts and space. R-2R DACs have been around since the 1980’s but the execution was historically poor, very expensive, or both. To do this style of conversion, you need dozens of very tightly toleranced resistors, and manufacturers simply couldn’t achieve those tolerances in the 1980s. R-2R makes for a better sound, but it takes so much space it requires it’s own box and precision (expensive) parts that are hard to make. It should come as no surprise that this technology was abandoned for many years.
In 2016, we met William Tse of Airist Audio, and began a conversation about R-2R DACs. Our goal was to take this beneficial technology, build it into a reasonable form factor, executing a no-compromise R-2R DAC at a price that would reach the majority of our audiophile community.
Two years later, the result is the RDAC. The method used is called sign-magnitude representation. On each channel we have 2 ladders, one dedicated to the positive side of the waveform, the other for the negative side. The purpose of this is to involve a smaller number of changing bits between positive and negative, without introducing too much bias.
Our Partner: Airist Audio
Some of you know Airist Audio for their Heron 5 amplifier that has been sold here on Massdrop.
The Heron 5 was their first product and a statement that you can make a great-sounding solid state amplifier by paying attention to phase (timing) performance rather than just frequency response (bass-to-treble linearity).
They had a different angle to amplification and a clear goal which they achieved.
Descriptions of the Heron 5 are never “sterile” or harsh, but warm, natural, and “involving”.
The design and execution of the Heron 5 led us to ask Airist about taking on our challenge of making an entry-priced R-2R DAC with the sound and performance of much higher-cost units.They understood what we hoped to offer, had clear ideas about how to approach the design, and believe in what Massdrop is trying to do.
(FYI: One of the reasons Airist Audio hasn’t yet followed up the Heron 5 with another product is because part of the team was working on tackling global health issues…turns out that similar technology is helpful in solving audio-related problems as well as tackling disease in populations. Another reason is that they were working on this challenge.)
Community Feedback/Community Validation
Great gear makes your music sound the best you have ever heard it. Or, great gear just gets out of the way and you forget about the gear and just listen to the music.
We’ve gotten several RDAC units out to community members to be sure it sounds good. We’ll get some review links up and ask them to post here.
Some early prototypes were circulating as far back as 2016. In that period of time, we have changed the inputs, the input selection switch, parts used on the PCBs, the form factor of the entire thing (to stack and look good with our amps), along with the power supply voltage & regulation.
Technical Chat
William Tse of Airist Audio will have limited availability due to his current projects but will try to be online to answer questions here in discussion for a few days.
We will then collect questions throughout the drop and relay the top questions to him in an additional First Purchaser Q&A after the drop ends.
While you can't change the Sigma Delta DACs that are already in your phone and all the various equipment all around you, now you have a choice that you can make for your audio system that won't cost you thousands of dollars.
This is an important launch for us, a high-level affordable separate DAC of great sound quality in a matching chassis to accompany our recent amplifier launches.
We’re excited for pics of your stack and to read if people stay up "way too late” listening to their rigs. :)
Two years later, the result is the RDAC. The method used is called sign-magnitude representation. On each channel we have 2 ladders, one dedicated to the positive side of the waveform, the other for the negative side. The purpose of this is to involve a smaller number of changing bits between positive and negative, without introducing too much bias.
Our Partner: Airist Audio Some of you know Airist Audio for their Heron 5 amplifier that has been sold here on Massdrop. The Heron 5 was their first product and a statement that you can make a great-sounding solid state amplifier by paying attention to phase (timing) performance rather than just frequency response (bass-to-treble linearity). They had a different angle to amplification and a clear goal which they achieved. Descriptions of the Heron 5 are never “sterile” or harsh, but warm, natural, and “involving”. The design and execution of the Heron 5 led us to ask Airist about taking on our challenge of making an entry-priced R-2R DAC with the sound and performance of much higher-cost units.They understood what we hoped to offer, had clear ideas about how to approach the design, and believe in what Massdrop is trying to do. (FYI: One of the reasons Airist Audio hasn’t yet followed up the Heron 5 with another product is because part of the team was working on tackling global health issues…turns out that similar technology is helpful in solving audio-related problems as well as tackling disease in populations. Another reason is that they were working on this challenge.)
Community Feedback/Community Validation Great gear makes your music sound the best you have ever heard it. Or, great gear just gets out of the way and you forget about the gear and just listen to the music. We’ve gotten several RDAC units out to community members to be sure it sounds good. We’ll get some review links up and ask them to post here. Some early prototypes were circulating as far back as 2016. In that period of time, we have changed the inputs, the input selection switch, parts used on the PCBs, the form factor of the entire thing (to stack and look good with our amps), along with the power supply voltage & regulation.
Technical Chat William Tse of Airist Audio will have limited availability due to his current projects but will try to be online to answer questions here in discussion for a few days. We will then collect questions throughout the drop and relay the top questions to him in an additional First Purchaser Q&A after the drop ends.
While you can't change the Sigma Delta DACs that are already in your phone and all the various equipment all around you, now you have a choice that you can make for your audio system that won't cost you thousands of dollars.
This is an important launch for us, a high-level affordable separate DAC of great sound quality in a matching chassis to accompany our recent amplifier launches.
We’re excited for pics of your stack and to read if people stay up "way too late” listening to their rigs. :)