PEQ1549 Parametric Equalizer


The PEQ1549 is a British inpired four band parametric equalizer with high-pass and low-pass filters all squeezed into the popular 500 format. This equalizer can do big things to sound and truly lives up to the catchphrase "giant sounding". We've also added 2X band range switching on the MF band section along with an AIR mode switch on HF band when you really want to add shimmer.


The PEQ1549 unit will allow you to carve up sound in ways that no small desktop mixer could ever imagine. It also has a Lundahl balanced drive output transformer option driven by a low noise/distortion THAT line driver. The input line receivers are by THAT Corp also.

All pots are long life (100,000 cycles) conductive plastic types with 11-detents for accurate settings. The knobs are custom injection molded to our specifications for a clean look and positive feel. It was no small feat packing this much EQ performance and features into such a small package.

Four Band Parametric Section

The PEQ-1549 is a four band equalizer implemented as state-variable filters using high quality op-amps and R/C networks. The state-variable design allows the filter parameters in each band to be varied independently and without interaction. The four bands cover frequencies up to 35 kHz and are divided as follows:

  • HF - High Frequencies (dual band) Normal Mode: 1.5 kHz to 16 kHz
    Air-Band Mode: 3.4 kHz to 35 kHz
  • HM - High-Mid Frequencies (dual band) Normal Mode: 350 Hz to 7.5 kHz
    2X Band Mode: 680 Hz to 16 kHz
  • LM - Low-Mid Frequencies Adjustable from 210 Hz to 2.3 kHz
  • LF - Low Frequencies Adjustable from 30 Hz to 320 Hz

Filter Section

The PEQ-1549 also provides a high-pass and low-pass filter section that may be switched in/out as needed for maximum flexibility. The filters provide the following functions:

  • HP High-Pass (Low-Cut)Sweepable from 25 Hz to 1.2 kHz
  • LP Low-Pass (High-Cut)Sweepable from 2.5 kHz to 35 kHz

Signal present and output overload LED indicators are also provided. Please refer to the owners manual for complete specifications.

PEQ Controls

The PEQ-1549 Controls

  • 1. Signal Present and Overload Indicators
  • 2. Power Status Indicator LED
  • 3. EQ Enable
  • 4. Low-Pass Filter Corner Frequency
  • 5. High-Pass Filter Corner Frequency
  • 6. High/Low Pass Filters Enable
  • 7. High-Frequency Shelf Mode Enable
  • 8. High-Frequency Cut/Boost
  • 9. High-Frequency Center Point
  • 10. High-Frequency High-Q Enable
  • 11. High-Frequency Air Band Mode Select
  • 12. High-Mid Cut/Boost
  • 13. High-Mid Frequency Center Point
  • 14. High-Mid High-Q Select
  • 15. High-Mid 2X Band Shift Enable
  • 16. Low-Mid Cut/Boost
  • 17. Low-Mid Frequency Center Point
  • 18. Low-Mid High-Q Select
  • 19. Low-Frequency Shelf Mode Enable
  • 20. Low-Frequency Cut/Boost
  • 21. Low-Frequency Center Point
  • 22. Low-Frequency High-Q Select

Frequency Response and Shaping

The plots below illustrate some of the basic response and frequency shaping capabilities of the PEQ-1549 equalizer in various modes.

Figure 1: HF Boost at Various Points

Freq Plot1

Figure 2: Combined LP and HP Filter

Freq Plot2

Figure 3: Normal and High-Q Mode

Freq Plot3

Figure 4: LF in Shelf Mode

Freq Plot4