Naim NAP 135 Monoblock Power Amplifiers

Here we have a super pair of classic “Chrome Bumper” finish NAP 135 monoblock power amplifiers from British specialist Naim Audio. Originally launched way back in 1984 but even today these units are still a very highly regarded amplifier especially by Naim aficionados. They have been fully serviced in August – all the reservoir caps, brackets, tants, axials, resistors, bipolar, zeners and bulbs have been replaced – and are in fully working condition. Cosmetically there are a couple of minor blemishes – please see photographs. Supplied with 12 months month warranty.
Naim Say….
The purpose of an audio amplifier is to drive loudspeakers without loss of musical information. In our view many commonly accepted parameters have little to do with loss of information and in some instances, such as the pursuit of large bandwidths or low distortion, unqualified acceptance of them can actually lead to the creation of mechanisms that bring such losses about. Dynamic output impedance, open loop bandwidth, slew rate, propagation delay and stability margins are only some of the many factors to which we attach Importance, and which must all be brought into positive balance.
With this balance in view, our amplifiers not only achieve low harmonic distortion, low noise and wide power bandwidth, but also have a constant dynamic output impedance over the whole audio bandwidth. They are able to drive reactive loads without any appreciable change in distortion and are not sensitive to the absolute impedance of the load.
The frequency response of our amplifiers at the bass end is dependent on the gain decoupling capacitor, and the half power bandwidth extends to below 5Hz. At the top end the response is controlled by a passive single pole filter and is 3dB down at 40kHz. The amplifiers do not slew rate limit within this frequency bandwidth.
The amplifiers will tolerate any load from 0 ohms to infinity without damage or instability, the output stages being protected by circuitry that measures the power dissipated. Prolonged running al high dissipation will cause the NAP 135 to become quite warm and should the heatsink temperature exceed 70°C the mains supply will be interrupted until the amplifier has cooled down.
The cases of the power amplifiers are all constructed in a similar way, using a heavy aluminium extrusion, which acts as a heatsink, to form the outer cover for an inner chassis inside which the entire amplifier is assembled. All connections are on the rear. All the amplifiers have large toroidal mains transformers. The NAP 135 has two regulated power supplies, each of which is rated at 40 volts and able to deliver more than 10 amps continuously.
The NAP 135 is a mono amplifier and has a temperature controlled fan mounted on a large internal heatsink to assist cooling when being used at high dissipation levels.
High quality components are used throughout, with great attention to detail construction. Many components are specially selected or manufactured to our own specification.
Specifications:
Power Output: 75 W into 8 Ω
Transient: 500 VA
Voltage Gain: +29 dB
Input Impedance: 22 kΩ
Operating Temperature: 0 – 50°C
Mains Supply: 240 V, 220 V, or 120 V; 50 or 60 Hz
Dimensions: 430 (W) x 300 (D) x 76 (H) mm

“The rhythmic diction permitted by the Naim gear is not just good or very good, it is superlative…. a group of instrumentalists playing with correct intonation, and in tune with each other, sounded more than usual like a cohesive ensemble…. The Naim combination provided me with countless hours of musical enjoyment.”
Neil Levenson, Fanfare, July/August 1987