If you are looking for an audio transformer that is truly suitable for an R2R DAC output, the Split-3k transformer is not a generic solution, but a component designed and optimized specifically for this application. In particular, the Split-3k was developed in collaboration with the designer of the chiurutu R2R DAC boards, available on eBay through his official store https://www.ebay.it/usr/chiurutu.
This transformer represents the official solution approved by the board designer himself. It has been tested, measured, and validated directly in real-world use as the best line transformer for interfacing his R2R boards. All comparative tests carried out with generic line transformers showed uncertain or non-repeatable results, with issues such as weak bass, attenuated highs, noise, interference, or clear impedance mismatches.
The cause of these problems is simple and technical. Generic transformers are not designed taking into account the real electrical characteristics of the R2R output of these boards, which operate with signals up to 5Vpp and require a well-defined load. The Split-3k transformer was created precisely to address these aspects, ensuring correct conversion from balanced to unbalanced, or vice versa, without introducing tonal alterations or instability.
Technical specifications:
- Turns ratio: 1:1
- Primary impedance: 3k with center tap
- Secondary impedance: 3k with center tap
- DC resistance: approximately 1k, consistent with the nominal impedance and with the correct loading of the DAC output
- Primary inductance: approximately 48 Henry at 100Hz
- Frequency response (secondary loaded with a 3.3k resistor):
- 20Hz -0.2dB
- 28kHz -1dB
Every parameter of the Split-3k transformer has been defined to operate correctly with the output of chiurutu R2R boards. The high primary inductance allows real low-frequency extension even with correct loading, while the nominal 3k impedance avoids unnecessary stress on the DAC and prevents the typical anomalies encountered with non-specific transformers. The result is a linear, stable, and repeatable frequency response, without coloration or loss of bandwidth.
Why choose the Split-3k transformer?
- Dedicated design: it is not a universal transformer, but one developed specifically for chiurutu R2R DAC boards.
- Real-world validation: it is the official transformer approved by the board designer, tested directly in application.
- No compromises: it eliminates the typical problems of generic transformers, such as missing bass or highs, noise, interference, and impedance mismatches.
- Long-term reliability: built with materials and design criteria focused on electrical and sonic stability.
If you are using a chiurutu R2R DAC board and want a truly correct output interface, the Split-3k transformer represents the most technically sound choice. For information, availability, or application details, you can contact me through the site form. I will be happy to answer any technical questions.