Electrodyne 2511 Equalizer

Electrodyne 2511 Equalizer


The Electrodyne 2511 is a dual mono pair of classic two-band discrete transistor reciprocal active inductor equalizers using early ’70s design technology. The custom inductors and output transformer are made by Electrodyne’s original maker to strict factory manufacturing tolerances as small as 2%. This allows consistent equalizer performance and repeatability from channel to channel that was not possible in the Sixties. Smooth performance and equalizer response from minimum to maximum gain at all frequencies provides unusually broad sonic and tonal options not experienced since the 1970s.

All current designs are built following actual original Electrodyne proprietary factory lab and engineering notes. And they have even gone to the trouble to have the designs reviewed and approved by original Electrodyne engineering staff for accuracy and adherence to company design criteria.


Equalizer Features:

  • All discrete transistor design
  • Custom wound Output Transformers (original manufacturer)
  • Custom wound eq Inductors (original manufacturer)
  • Custom concentric gain/frequency switches (mil-spec quality)
  • Original design knobs and control levers (original manufacturer)
  • Rugged powder coated steel chassis
  • Heavy-gauge Anodized Aluminum Face Plate
  • All XLR I/O
  • Active balanced discrete transistor input
  • Transformer balanced output
  • Individual Low and High Shelving Switches per band for each channel
  • Each eq band network is completely bypassed when its gain control is placed at the “0” mark
  • On/Off Power Switch
  • Red LED Power Indicator


Video: Ken Hirsch on the history of Electrodyne

Video: Introduction to the 2511



Input Active balanced discrete transistor impedance converter
Output Custom wound large format multifilar transformer
Output Impedance 600?
+/-12 db gain range Equalize or attenuate
4 frequencies selectable per band:
LF 40, 100, 250, 500hz
HF 1.5k, 3k, 5k, 10k
Peak/Shelf sw each band:
Shelving at all frequencies, Peaking: 250, 500 (LF), 1.5k, 3k and 5k (HF)
Distortion 0.03% typical
HF peaking Q = .35
LF peaking Q = .7
HF shelving slope approx. 3dB/ oct
LF shelving slope approx. 4dB/ oct
Maximum output +30dbu at less than 0.8%thd, +29.5dbu at 0.06%thd
Frequency response +/- 0.25db, 70khz typical (no filters engaged)
Signal to noise -85dB typical