Preamplifiers — Karan Acoustics MASTER COLLECTION LINEb

The Master Collection LINEb is a single-chassis line preamplifier from Karan Acoustics, and it sits in the Master Collection next to the two-chassis LINEa. The maker announced that a phono stage and stereo and mono power amplifiers would follow in the same collection. The US price was USD 28,000.

Key specs that matter

Connections comprise four XLR line inputs, two RCA line inputs and two balanced XLR outputs, with no single-ended output provided. Gain is switchable between +6 dB and +9 dB. Input impedance is 30 kohm and output impedance 90 ohm. Response is flat from 20 Hz to 20 kHz within 0 dB and extends from 1.5 Hz to 3 MHz at the -3 dB points. THD is 0.003% at full output across the audio band, with IMD also at 0.003%. Signal to noise ratio exceeds 120 dB unweighted. Nominal output is 1.55 V RMS and the maximum is 18 V RMS balanced into 600 ohm, while the input accepts up to 5.4 V RMS at 6 dB gain or 3.6 V RMS at 9 dB before saturation. Rise and settling time is under 450 ns. The case measures 504 x 141 x 390 mm and weighs 17.4 kg, and power draw peaks at 60 W. A ground lift switch and an IEC mains socket complete the rear panel, and Karan gives a 5 year warranty on parts and labour.

Engineering and use context

Every circuit in the LINEb is symmetrical and biased into class A. The signal path is fully differential and direct coupled, meaning no capacitors are placed between input and output, and custom DC servo circuits remove any offset instead. Volume is set by a fourfold fully balanced attenuator built from fast relays and custom non-magnetic resistors with 0.1% tolerance, which keeps the two halves of each balanced channel matched at every step. Karan states that the power supply has nine stages of current and voltage filtering and regulation per channel, with separate transformers and regulation for left and right. Audyn-Cap Reference parts appear wherever capacitors remain. The heavy aluminium chassis rests on CMS CS2 isolation footers, and a solid aluminium circular remote handles volume and the menu functions.

Pairing

The LINEb needs power amplifiers fitted with XLR sockets, and its two output pairs can feed a stereo power amp alongside a powered sub, or two monoblocks with separate cables. The low output impedance allows long balanced runs to amplifiers placed beside the speakers. The two gain settings help match sources and power amplifiers of different sensitivity.

Alternatives

The Karan Acoustics Master Collection LINEa is the two-chassis preamplifier in the same series.