McIntosh MA7000

Beschrijving / Description

MA7000 is the biggest so far McIntosh integrated amplifier. It is also one of the heaviest almost 45 kg! It is classic McIntosh design. Front panel made of thick glass. In the upper part we can find blue illuminated power output Watt meters calibrated to show even the smallest power output. Meters are there just to satisfy customers. Between them you will find two red LEDs that are indicators of one the the company's unique patents Power Guard. This is a circuit that protects the device from overdriving the power. It doesn't simply cut the power but gently compresses power peaks so that the signal waveform, Power Guard is comparing, stays the same and there are no audible distortions. Below you will find a nice row of controls two bigger ones at the sides, and five small in the middle. On the left side there is a balance control, on the right a volume control. Small controls in the middle are in fact complex equalizer controls. Equalizer is considered to be unnecessary or even harmful nowadays, but when correctly designed it might come handy surprisingly often. The real reason of avoiding equalizers is simple no magic about it well designed equalizer costs a lot, especially like this one with five frequencies: 30/150/500/1500/10000 Hz. There is no on/off button it doesn't process the signal if control is in the middle position. Beneath there is a row of push-buttons input selector (6 linear inputs and one MM phono input), mono, output (x 2) and mute. Rear panel connections are placed in two groups. One is located in the lower part of the chassis, and the other one in the upper part.. Lower part consists of gold finished RCA connectors and XLR preamplifier's output, and in the upper part two balanced XLR inputs with two RCA unbalanced right beside them, plus excellent WBT speaker terminals like in tube amplifiers separate for different loadings - 2/4/8 ohm. Preamplifier and amplifier sections are connected via jumpers.

As already mentioned the inside is divided into two parts. Lower part is a preamplifier based on electro-magnetic switches of input selector, transistors and operational amplifiers NE5532. We can find there another circuit - TLC174 by Texas Instruments, eight-channel amplifier, working most likely as tone control. In the upper part of the device we will find power transistors fixed directly to huge radiators, that are visible at the side of the device. There are also four big capacitors their task is to level current fluctuations for this part of device. The secondary winding is common for both power transistors. There is a separate one for preamplifier, hence advanced power supply in the lower part of the amplifier, where each section - input, driver, meters, safety circuits and so on have their on power supplies. The transformer (EI) itself is huge, packed in a metal case filled up with some dumping material. Autoformers (output transformers) were put into similar cases. All transformers are located in the front of the chassis. They are not hidden under the top plate of the chassis so together with beautiful front they make a nice, attractive design. There are twelve Power Transistors used in each channel of the MA7000Power Output Circuitry. Those are special elements called Thermaltracks. This allows for the instantaneous and accurate monitoring of the power transistor temperature. A specially designed bias circuit precisely controls and adjusts temperature of power transistors so that they always work in the same conditions. As mentioned before, balanced outputs (two pairs) are located separately in the amplifier's part of the chassis. XLR connectors are partnered by RCA ones, right behind the latter signal is symmetrized in inexpensive, low-noise NE5532 circuits. Signal goes from there to the lower part of the amplifier through computer cable.

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McIntosh MA7000

Beschrijving / Description

Specificaties / Specifications