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.