You are here

Roger Mayer Dottore XFM DR1

Passive Inductor Equaliser By Paul White
Published August 2022

Roger Mayer Dottore XFM  Passive Inductor Equaliser

Many of the best‑loved classic equalisers used a passive inductor‑capacitor (L‑C) circuit, in most instances followed by a stage of amplification to compensate for any level loss: the legendary Pultec EQP‑1A is a classic example of this approach to EQ design. According to designer Roger Mayer, a passive L‑C EQ works particularly well on the non‑symmetrical waveforms typically produced by most musical instruments and voices, which are not always treated optimally by a circuit that relies on negative feedback (as found in most general active EQ circuitry).

His Dottore XFM is a two‑channel, true passive L‑C equaliser based on high‑quality audio transformers; one of the transformer windings in each channel provides the necessary inductance. In bypass or boost mode, the Dottore XFM is also able to connect a balanced source into an unbalanced input without any loss in the signal level (typically you’d lose 6dB when feeding balanced...

You are reading one of the locked Subscriber-only articles from our latest 5 issues.

You've read some of this article for free, so to continue reading...

  • Log in - if you have a Subscription you bought from SOS.
  • Buy & Download this Single Article in PDF format £1.00 GBP$1.49 USD
    For less than the price of a coffee, buy now and immediately download to your computer or smartphone.
  • Buy & Download the Full Issue PDF 
    Our 'full SOS magazine' for smartphone/tablet/computer. More info...
  • Buy a DIGITAL subscription (or Print + Digital)
    Instantly unlock ALL premium web articles! Visit our ShopStore.

Claim your FREE 170-page digital publication
from the makers of Sound On SoundCLICK HERE