Усилители мощности стерео — Concert Fidelity CF-080LSX4

The CF-080LSX4 is a hybrid line stage preamplifier made by Concert Fidelity, a workshop in Nagano, Japan, where founder Masataka Tsuda has designed and assembled every unit since 1987, and it belongs to his Reference Series. It is listed as revision V4.5 and follows the CF-080LSX3 at revision V4.0, which already had an XLR socket on its fourth input. The LSX4 keeps that balanced input and adds the possibility of a balanced output as well. Concert Fidelity quotes no list price.

Key specs that matter

Four line inputs are provided on RCA jacks, and input 4 can also be fed through XLR. Every input presents 100 kohm to the source. The standard output is one RCA pair, with an XLR output available to order. Gain is switchable between 6 dB and 12 dB in the standard build, and a 12 dB and 24 dB version can be requested for low-output sources. Two 12AU7/ECC82 double triodes do the amplifying, and a single 6V4/EZ80 or 6CA4/EZ81 rectifies the high-voltage supply. The case measures 450 mm across, 100 mm tall and 310 mm front to back, and the net weight is 12 kg. Remote volume control is an extra-cost option.

Engineering and use context

Tsuda calls his circuit approach Direct Signal Path Technology, or DSPT, and applies it here to both the input switching and the volume control, because his goal is to cut down how long the audio passes through circuitry before it reaches the output. Level is set by a minimalist dual electronic volume control. The 12AU7 stage runs in cascode configuration for low distortion, and the tubes are meant to be rolled, since the unit ships without any valves fitted. Mains transformers are wound for the destination country, with versions for 100 V, 110-120 V, 220-230 V and 240 V supplies, and the factory warns that a unit used outside its intended country loses warranty cover.

Pairing

A 100 kohm input is an easy load for tube DACs, phono stages and solid-state sources alike, so no buffer is needed ahead of the preamp. The DAC-040Mk2 converter from the same maker shares the case size and weight, which lets the two stack as a matched pair. On the output side the Reference Series offers the ZL-120FX2 and ZL-200FX2 monoblocks and the ZF-100FX stereo amplifier, while the 220 kohm input of the DHS-300B single-ended amplifier accepts the RCA output without difficulty.

Alternatives

The Concert Fidelity CLS-050 Mk2 is the other line stage in the range, built around a pair of 6V6 tubes with a custom output transformer, an ELMA attenuator and a built-in headphone amplifier.