Knif Audio Soma Passive Mastering EQ

Soma is a clear departure from the old "passive EQ:s are for general shaping only" paradigm.

It is the only commercially available passive EQ with real Q adjustment, which makes it more usable and accurate than other products which use only a resistor based Q adjustment which affects boost/cut amount and does not offer a wide range.

It is not surprising that this type of ”real Q adjustment” passive EQs have not existed before Knif Soma. When passive circuits reigned the EQ world there was no feasible technology available for the rather complex requirements. When engineers started to require more control, active circuits were already there and thus passive designs were abandoned until it was realized that they offer superb sonic results. It was taken for granted that they have their limitations and were used accordingly.

Well implemented real Q adjustment in passive EQs requires logic circuits and a lot of subminiature relays (around 140 pieces in Soma). Signal path in Soma is short, because frequency and Q adjustment (switching different capacitors and inductances) is executed locally and signal is taken to the front panel for gain control only.

MS-matrix in Soma is passive, transformer based, and does not add one single component in the signal path and thus does not degrade sonic performance. Input and output transformers have multiple windings which are switched locally, with relays, to perform sum and difference operations.

Filter section is very simple. There is the possibility to switch S-channel high pass for 6dB/oct for ”elliptical” bass equalizing.

Coils (enclosed in mu-metal) are hand wound by Mr.Knif and have maximum amount of taps to make the Q-adjustment possible. Make up gain amplifier is a simple two-stage thing with moderate amount of feedback, with tubes of course. Soma has individual discrete regulators for anode supplies, mu-shielded signal transformers, all teflon/copper/silver wiring, no connectors on signal path.

PSU operates on 240V, EU power cord included.

US and EU parcels ship via UPS, ETA 1-7 working days from pickup day zero. That also applies to most locations worldwide.

All shipments are fully insured.

Bigger shipments requiring pallets or custom made crates ship to US, CA, JP, CN, AU and other outside of EU locations via DHL Air Freight, ETA is normally approx. 7-14 working days from pickup day zero.

Big shipments inside EU ship via different freight companies, recently mostly via ACE Logistics. Freight forwarders can use different courier companies for deliveries to final destinations.

Palletising and crating time can vary depending on the size of the shipment and packaging queue. We pack all our shipments with great care.

You are most welcome to pick your order up yourself from our Retrosonic Pro Audio showroom, studio and warehouse in Tallinn, Estonia.

We ship worldwide – contact us for a personal shipping quote or any other questions.

VAT (Value Added Tax) can be deducted if you have a company with a valid EU VAT number or if you're based outside of the EU. Non-EU buyers pay all and any import tax and duty as regulated by their local customs.