Updated: Dec 3, 2020
A customized 3-pin RCA jack (pre-order now):
Why balanced RCA?
Pictured below, you can see the huge size differences between the balanced jacks and single-end jacks. Balanced audio usually comes with a compromise; the XLR jacks and plugs are more than double the size of regular single-end equipment:
Some audio enthusiasts would mention that there exists the diminutive “3.5 Pro” and “Mini XLR-5” jacks. However, we did not favour those solutions because they are uncommon and unpopular. The “3.5 Pro” jack also has crosstalk issues. Within the Hi-Fi audio industry, both RCA and XLR-3 jacks continue to be the most popular and widely used standards.
Therefore Khadas believed that we must design our Tone2 DAC with the end-user in mind, and building-in small but unpopular audio jacks just wouldn’t do. So we decided to continue on with the popular RCA standard that we would update to incorporate balanced audio.
Differences between Single-End & Balanced-Audio:
How did we design it?
After consulting with up to seven different suppliers and manufacturers, we finally found one who was up to the challenge of both designing and manufacturing a new kind of RCA jack and plug. Depicted below is our balanced RCA jack and plug design. The structure of each signal line is shown in yellow, blue and pink:
Our patented “balanced-RCA design” is also compatible with standard RCA cables, so you won’t have to buy a special RCA cable just to use the Tone2 DAC; it is backwards-compatible with existing RCA cables and will function in single-end mode.
The “protective-patent” (CN211265767U) covers both the balanced RCA jack and plug, and will ensure that our design remains free and open source for the community. We did this to prevent predatory entities from co-opting and patenting this new design to corner the market.
If you are curious about the technical details, such as how we solved the crosstalk issue, you may refer to the original patent document.
3rd Party Usage:
RCA connector vendors, feel free to use our patents to design new balanced-RCA jacks. However, please register with Khadas via ‘firstname.lastname@example.org’. We want to ensure that all balanced-RCA jacks are made with good design and user experience. Note: you must follow the “two holes” design.
For DAC / amp vendors, same as above, however you need to “label” your product as incorporating ‘Khadas Balanced-RCA’.
In addition, we would be grateful if all vendors mentioned above would add a link to khadas.com/balanced-rca in their relevant product descriptions.
A smaller balanced-RCA jack enabled us to design a thinner and lighter Tone2 DAC. As you can see, it is 4.4mm thinner than a prototype aluminum case designed for Tone1, and at least 8.3mm thinner than an XLR-3 jack:
This also enables Tone2 to be used in more situations, such as with smartphones:
We have also designed a “Balanced-RCA Plug to XLR-3” converter cable, so you can use your Tone2 DAC with popular industry-standard XLR-3 pre-amplifiers, amplifiers and speakers: