MBL Noble Line N11/N15 Preamp & Monoblock Power Amps Unity Gain

Unity Gain

Most amplifiers still offer far higher gain (amplification factor) than is strictly necessary when used with today's relatively high-output sources. We regularly see integrated amplifiers, or pre/power combinations, with a total +45dB gain (or x178) when, for example, a gain of +27.8dB is all that's required to raise the 2V from any of today's digital player/DACs to the N15's rated 300W/8ohm. This excessive gain is, on the whole, a throwback to the 1960s and '70s when audiophiles were reliant on tape decks and FM tuners with a mere 200mV output.

In 2022, only half the available gain of most amplifiers is used, limiting maximum S/N, and relegating the volume control to where it's least linear and where channel balance is poorest. In many pre/power combinations this means the preamp is being used as little more than an active attenuator and buffer...

We've seen a few amplifiers with appropriately reduced gain – the Rotel Michi X3 and X5 [HFN Apr '21 & Jul '21], for example, just as Constellation Audio [HFN Jul '15, Oct '19 & Dec '19] allows the J-FET input stage of its power amps to be bypassed, reducing gain from typically +26dB to +12dB and relying on the partnering preamp to 'make up' the volts. MBL takes the opposite approach to achieve the same ends (it's no coincidence the N15's gain is exactly +27.9dB). In standard guise the N11 pre offers +9.8dB overall gain (balanced in/out) while 'Unity Gain' limits this to +0.2dB – equivalent to reducing the volume from '100' to '70' on its display. Provided your source can deliver in excess of 2V (balanced) then the N11/N15 can always be driven to full output with no 'wasted' gain, and the N11's motorised volume control swept through 100% of its range. PM

MBL Akustikgeräte GmbH & Co. KG
Berlin, Germany
Supplied by: Stranger High Fidelity, Real World Studios, Wilts
07702 155847