The Ruff Records EQP1A utilizes a flexible, building-block approach to building an EQ in the tradition of the EQP1 that is much more affordable than most Pultec clones, while retaining a close resemblance to the original response curves. Like the original, the EQP1A features a passive filter section, relying on the inherent filtering capabilities of capacitors, followed by a tube makeup gain circuit. Unlike the original design, there is no need for an interstage transformer between the EQ and the makeup gain stage (assuming that the builder chooses to utilize Ruff Records’ own tube makeup gain circuit, as opposed to an op-amp-based circuit). Additionally, there is an added option of a mid cut/boost section not found in the original design.
Poor Man’s EQP1A Features:
- 16k, 10k, 8k, 5k, 4k, and 3k high shelf cut/boost
- 200hz, 150hz, 100hz, 60hz, 30hz, and 20hz low shelf cut/boost
- Frequency values can be changed using Ruff Records’ capacitor calculator spreadsheet
Price:
- adjusted PCB cost (x2 PMEQP1A, mid control, tube makeup gain, and power supply: £23.5
- $25 for Antek AN-05T240 toroid power transformer
- £49.79 for Sowter 3575 input transformer
- £55.57 for Sowter 5069 output transformer
- final cost will depend upon components and enclosure used
More Information:
- PCBs available from Ruff Records
- View the GroupDIY discussion/info thread
- View the GroupDIY support/documentation thread
- View the GroupDIY tube makeup gain circuit discussion/info thread