Усилители мощности моно — Trafomatic Audio Glenn

The Glenn is a parallel single-ended monoblock from Trafomatic Audio that uses two 300B direct heated triodes in each chassis. Trafomatic describes it as a crossbreed between two earlier models, the Experience 2 MK II and the Experience Reference 300B, and designed it to work with the different 300B tubes on the market. Each unit is hand built in Serbia.

Key specs that matter

Input impedance is 47 kOhm and input sensitivity is 3 Vpp, and each amplifier carries an XLR socket plus an RCA socket. Output taps are provided for 4 and 8 ohm speakers. Total harmonic distortion is 4% at maximum power with a 1 kHz signal. Signal-to-noise ratio is 90 dB. Frequency range runs from 8 Hz at minus 2 dB to 60 kHz at minus 3 dB. Each monoblock draws 250 VA and is supplied for 230 V at 50 Hz, with 100, 120, 220 and 240 V versions at 50 or 60 Hz available on request. Dimensions are 480 x 340 x 270 mm and weight is 26 kg per unit.

Engineering and use context

Besides the two 300B output triodes, each chassis holds an E182CC driver valve and a 5U4G rectifier valve. Output power depends on which 300B type is installed and on the plate dissipation setting chosen. Negative feedback is adjustable between 0 dB and minus 3 dB in 1 dB steps, so the owner can run the amplifier with or without feedback. Stages are joined by interstage transformer coupling. The anode supply is smoothed by a C-L-C filter that pairs a Trafomatic choke of high inductivity with Mundorf MLytic HV electrolytics. Trafomatic makes all the magnetics itself - a 6 kg output transformer on a double C-core potted in epoxy resin, a 10 kg mains transformer also on a double C-core, the filter choke and the interstage transformer. The output transformers are oversized and wound in many sections sized in harmonic proportion, a construction intended to keep leakage inductance low. Loudspeaker terminals are from WBT, and the valve sockets are made of Teflon.

Pairing

A stereo system uses two Glenn chassis. The balanced XLR socket suits a preamplifier with balanced outputs, while the RCA socket takes a single-ended line stage. Speaker cables go to the output tap that matches the rated load of the speaker, and the feedback switch lets the owner choose the setting that suits that load.

Alternatives

Trafomatic Audio also makes the Elysium, a single-ended Class A monoblock driven by one Eimac 250TL direct heated triode per chassis.