Gyraf Pultec Tube EQ PCB Set

The Gyraf Audio DIY Pultec PEQ1A Equalizer, commonly known as the G-Pultec, offers audio enthusiasts the opportunity to build their own version of the legendary Pultec PEQ1A. This project simplifies the original design while preserving the distinctive sound quality that has made the Pultec EQ a staple in professional recording studios for decades. With comprehensive documentation, easy-to-follow schematics, and readily available components, the G-Pultec is an ideal project for DIY audio enthusiasts seeking high-quality sound.

Overview

The G-Pultec is an updated, easier-to-build version of the classic Pultec PEQ1A. It features a “no feedback” SRPP gain stage, standard rotary switches, and PCB-mounted components for straightforward assembly. This design retains the beloved characteristics of tube audio while making the construction process more accessible.

Key Features

•Classic Pultec Sound: Emulates the iconic Pultec EQP-1A sound.

•SRPP Gain Stage: Utilizes a no-feedback SRPP gain stage for authentic tube audio.

•Standard Components: Uses commonly available components, including standard rotary switches and off-the-shelf power transformers.

•Enhanced Usability: PCB-mounted switches for easier assembly and more low-frequency cut/boost options.

•Optional Balancing: Unbalanced input with an option for transformer balancing.

Building the G-Pultec

Preparation:

1. Component Verification: Ensure all components match the specified values before starting assembly.

2. PCB Layout: Follow the provided PCB layout files, printed to the exact scale for accurate construction.

3. Heat Management: Apply appropriate heat sinks to the voltage regulators to prevent overheating.

Assembly Tips:

•Transformer Data: Utilize the provided schematic and component list for accurate transformer specifications.

•Tube Selection: Use the recommended ECC88/6DJ8/6922 tube for optimal performance and lower output impedance.

•Grounding: Ensure proper grounding of the power supply and signal path to avoid noise and hum.

Adjustment and Calibration

Component Placement:

•Ensure all resistors, capacitors, and inductors are correctly placed according to the schematic.

Calibration Steps:

•Frequency Response: Adjust the EQ settings and test the frequency response to match the desired sound profile.

•Gain Staging: Verify the gain staging to ensure proper signal flow and minimal distortion.

•Transformer Balancing: If using an optional input transformer, balance the input and output levels for optimal performance.

Troubleshooting

Common issues may include:

•Incorrect component values or placements.

•Soldering errors leading to shorts or poor connections.

•Power supply issues due to incorrect transformer wiring or insufficient heat sinking.

Resources:

•Online Forums: Join forums like GroupDIY for community support and troubleshooting advice.

•Detailed Guides: Follow the detailed assembly and calibration guides provided by Gyraf Audio.

Enhancements and Customizations

Inductor Winding:

•Resources and guides are available for winding your own inductors, which can enhance the performance and customization of your G-Pultec.

Power Supply Modifications:

•Customize the power supply using off-the-shelf transformers for different voltage requirements or improved stability.

Conclusion

The Gyraf Audio DIY Pultec PEQ1A Equalizer is an exceptional project for audio enthusiasts seeking to replicate the renowned Pultec sound. With its simplified design, accessible components, and detailed documentation, the G-Pultec offers a rewarding building experience and a high-quality addition to any recording setup. Whether you are a seasoned DIYer or a newcomer to audio equipment construction, the G-Pultec is an excellent choice for enhancing your understanding of audio electronics and achieving professional-grade sound.

See the documentation tab for build docs.

Additional Resources:

•Gyraf Audio DIY Pultec PEQ1A Page

•GroupDIY Forum

Explore these resources for more detailed instructions, schematics, and community support as you embark on building your own G-Pultec equalizer.

*Analog Classics does NOT provide build support for this project.