Integrated Amplifiers

Editor PM caught up with Vinnie Rossi during 'lockdown' on both sides of the pond, intrigued to discover VR's earliest influences.

'I studied electrical engineering in the '90s while working as a test engineer for a major telecom giant', Vinnie began, 'but I was also an audio hobbyist and so, in 2004, I followed my passion and established Red Wine Audio where I focused on battery-powered components. However, in 2014 I introduced a modular integrated called LIO that had an ultracapacitor supply, and the move away from battery PSUs prompted a change in brand name'.

And direct-heated triodes – where did these spring from? 'I used 8 and 9-pin indirectly heated triodes in my linestage designs before seeking the "holy grail" of valves – the 4-pin directly heated triode (DHT)', says Vinnie. 'Once I began listening to them, I was quickly put under their magic spell. The L2i-SE's DHT preamp is convertible and accommodates numerous 4-pin DHTs including the 300B, 2A3, 45, PX4, SV811, 71A, T-100, 101-D and 205-D – all via the filament voltage selection switch on the rear panel.'

A quick glance at the L2i-SE might suggest it's a 300B SET amplifier, but these tubes are not driving speakers, they are in the preamp stage. So why the high distortion? 'My preferred topology features no driver tubes, no feedback, no output transformers, and just 6 to 9dB of gain, depending on the tube used. It sounds simple, but designs like this are rare, and very challenging to implement with low levels of noise.