Предусилители — VTL TL 2.5i

The TL-2.5i is the valve line preamplifier of VTL's Performance Series, from the California company founded in 1981 and led by Luke Manley. Hand-built in California, it brings much of the circuitry and power supply design of the larger TL-5.5 Series II into a simpler and more affordable chassis. It can be fitted with an internal phono stage for MM and MC cartridges, either at purchase or later.

Key specs that matter

The line stage uses two 12AU7 and two 12AT7 tubes. Gain is switchable between 8 dB and 14 dB, maximum output is 30 V RMS and THD is 0.02% from 20 Hz to 20 kHz. Signal-to-noise is 90 dB and channel separation 75 dB at 1 kHz. There are six line inputs, or five when the phono stage is fitted, two pairs of RCA outputs, a tape loop, a record output and a processor loop for home theatre. Power consumption is 100 W, or 150 W with the phono stage. The chassis measures 483 x 381 x 102 mm wide, deep and high, at roughly 11 kg.

Engineering and use context

VTL designs its line stages around a high-current, low-impedance tube output. Each gain stage has its own stiff power supply, the supplies are fully shielded, and the power transformer is designed for very low radiated field. Negative feedback was reduced compared with earlier VTL preamplifiers. Volume and balance use 27 mm laser-trimmed controls with remote volume and mute, and a mono function works on line and phono inputs. The optional phono stage uses two 12AX7 tubes for MM with 37 dB of gain, while an active MC mode adds a 12AU7 for 52 or 58 dB. A step-up transformer route gives 60 dB, and MC loading can be set between 100 ohms and 47 kohm. The circuit board is glass fibre with heavy copper traces, the chassis is 16-gauge steel with aluminium top and sides, and the RCA jacks are gold plated. Finishes are silver or black, and the IEC power cord is detachable. The TP-2.5i external phono stage offers the same circuit in its own chassis for owners who prefer a separate unit.

Pairing

The high output voltage and low-impedance tube output stage suit VTL's ST-85 and ST-150 stereo amplifiers and most tube and solid-state power amplifiers with single-ended inputs, and the second pair of RCA outputs allows bi-amping or an added subwoofer. The low gain setting helps with high-output digital sources, and the processor loop integrates a surround system at unity gain.

Alternatives

VTL's TL-5.5 Series II is the larger line preamplifier of the range with balanced operation.