The Audio Design Guide
Andrea Ciuffoli and his Audio Design Guide webpage

Andrea Ciuffoli is an Italian audiophile with quite an extensive web site at audiodesignguide

His site contains a long list of designs using Lundahl transformers. Now with the newest added designs at the top of the list:

• • Extreme high-end hybrid amplifier
    with LL1668 anode chokes in the tube stage (June 2014)
  • HQ reference DAC,
    some versions using the LL1684 in the output stage (June 2014)
  • A Digital Room Correction project
    using LL7902 transformers for galvanic isolation, and EMU 0404USB + Behringer ECM8000 for measurements (March 2011)
  • The new (March 2011) reference 300B amplifier – 6W
    with LL1623/60mA, LL1648 and LL1638. (Old link to 4300B amplifier removed)(March 2011)
  • Hi-End Class A-AB Hybrid Amplifier
    using LL1671/20mA interstage transformer (December 2010).
    • Hi-End Class A-AB Hybrid Amplifier, balanced (March 2011)
    • Hi-End Class A-AB Hybrid Amplifier, ”End” version (December 2011)
    • Hi-End Class A-AB Hybrid Amplifier, ”End” version 2 (October 2021)
  • A Hi-Resolution System with EMU 0404 USB,
    using LL7903 in a DAC output circuit (August 2010).
  • A ”No compromise” Phono Preamplifier,
    using LL1931 and LL1660AM/10mA transformers and LL1668 chokes (March 2009).
  • Singel-end headphone amplifier
    with LL1689AM transformer for ultimate performance (March 2009)
  • The ”Final” DAC version,
    using LL1660AM/10mA amorphous core transformers (Aug. 2008).
  • A DAC project
    with LL7903 transformer (June 2007).
  • A new 845 Single End Amplifier
    using LL1620/90mA, LL1671/20mA and LL1638/8H (June 2007).
  • A Power Follower project
    very short signal path and LL1660 transformer (June 2007).
  • EL34 Parallel Single Ended
    with LL1627/185mA and Lundahl mains and chokes (Aug. 2004)
  • 300BXLS Single Ended Amplifier
    with LL1623/120mA and Lundahl mains and chokes (Aug. 2004)
  • Ultra Fast High Power Single Ended Amplifier
    with LL1627/185mA and Lundahl mains and chokes
  • The reference 2A3 amplifier – 2W
    with LL7903, LL1660/10mA, LL1667/5mA, LL1623/60mA and Lundahl mains and chokes
  • 6BX7-based Single Ended Single Stage (SESS) amplifier for STAX electrostatic headphones
    using LL1660/10mA, LL1667/5mA and Lundahl mains and chokes
  • Simple transformer driver for STAX electrostatic headphones
    using LL1630/PP.
  • Single ended tube amplifier for Stax electrostatic headphones
    with LL1660/25mA
  • A 300BXLS Single Ended Amplifier using the KR Electronics tube KR300BXLS
    with LL1623/120mA, LL1667/5mA and Lundahl mains and chokes
  • Hi-End Push-Pull Amplifier ”- 20W no feedback!”,
    using LL1623/PP, LL1660/10mA and Lundahl mains and chokes
  • 2A3 PSE – Parallel Single Ended ”The New Reference Amplifier”,
    using the LL1627/120mA, LL1660/10mA and Lundahl mains and chokes
  • KT88 push-pull amplifier
    using LL1623 OPT
  • SV572-3 Single Ended Amplifier
    using LL1620/90mA, LL1660/25mA and Lundahl mains and chokes.
  • 300B SE – Single Ended Amplifier ”The Little Reference”,
    using LL1623/90mA and LL1660/10mA
  • 300B PSE – Parallel Single Ended Amplifier with fixed bias implementation,
    using LL1627/140mA, LL1660/10mA and Lundahl mains and chokes
  • 300B PSE – Parallel Single Ended Amplifier ”The Reference”
    using LL1627/140mA, LL1660/10mA and Lundahl mains and chokes
  • SETA Single ended cathode follower vacuum tube amplifier
    using LL1627/140mA, LL1660/10mA and Lundahl mains and chokes.
  • DAC 2.0 with the D/A Converter N°3 board by ARMONIA Hi-Fi and Lundahl LL1636 transformers
  • An 845 single end amplifier
    using LL1620/90mA, LL1671/50mA and LL1667/5mA.

Project-independent:

• Hybrid power supply using both diodes and tube rectifiers to get the best of the two worlds. We think this is excellent as it works very well with our mains transformers.
• Tube output transformer selection list. This sheet with tables, provided by Andrea Ciuffoli, is a guide to find the most appropriate Lundahl output (and interstage) transformers to selected tubes.

Who is Andrea Ciuffoli

Andrea Ciuffoli is a software engineer, working with Internet technologies. He is involved in the Audio Hi End DIY since 20 years ago. His aim is to search for new solutions, to try new ideas and to look for any improvement. He is not involved with any financial business in the field, the Andrea’s wish is to improve and share his know-how both in the Electroacoustics and in Electronics. Being a Spice expert most of his conceptual work is CAD oriented, such an expertise, put together with an excellent ability in crafting ‘fast’ his devices, gives him the possibility to cover all the aspects of the hobby.

(by Francesco Pintavalle)