The Stevens and Billington Limited EQ600 LCR RIAA Equaliser module

The 600 Ohm passive LCR RIAA module is now available. The modules are priced at £300* per pair

Please contact us to order. *Please note prices exclude VAT and delivery. We now accept PayPal!

The EQ600 RIAA Equaliser module - an introduction

The Stevens and Billington Limited EQ600 RIAA Equaliser module is a combination of passive components incorporating a pair of highly specified inductors as primary frequency response and sound determining components. It is a raw module encapsulated in a transformer can requiring to be used in the context of a suitable piece of equipment. It is not a finished product ready for use in an audio system. The primary application is for the accurate equalization of the RIAA cutting equalization applied to LP in the context of a Phono Equalizer/Preamplifier. If used in the feedback loop of a cutting amplifier it could also be used to provide an accurate RIAA pre-emphasis for cutting LP's.

Technical details

The RIAA EQ module transformer is housed in a Mu-metal shielding can that measures 60.25mm (2^3/8in) in diameter x 72mm (2^13/16in) in height, excluding the connecting leads. No in-built mounting hardware or mounting provisions are included, due the substantial size and weight of the module, which would make the conventional methods unreliable. The best mounting solution is to apply the same type of mounting clamp used for large size electrolytic capacitors (available from any good electronics supplier).

The input and output connections are made via silver coated 0.6mm dia. (22gauge) copper wire.  The EQ-600 is designed to operate in a 600 Ohm matched impedance system, as provided in many broadcast and similar applications. Either the load provided to the RIAA Module must be 600 Ohm in which case the drive impedance is immaterial and the RIAA Module presents the driving circuit with a frequency independent 600 Ohm Load (+/-5% or closer tolerance) OR the impedance of the source (drive impedance) must be very accurately 600 Ohm, in which case the load impedance is immaterial.

The specifics of the amplification stages are really up to the designer using the RIAA Module. The degree of freedom in choice of topology, active device etc is huge and even a most scant coverage would require a long article. In any application, the RIAA circuit will cause around 20db attenuation at 1KHz. Possibilities include Operational Amplifiers set to give 30db gain, Mu-Follower stages using a 6SL7 or similar valves for the gain parts and suitable follower devices and many other Valve, hybrid, discrete solid state or monolithic integrated solutions. As a rule the output of the first amplification stage should either be of a matched impedance of 600 Ohm or of low source impedance and able to drive a 600 Ohm load to significant level.

RIAA Block diagrams