Get the guaranteed best price on Powered Mixers like the Soundcraft GigRac Powered Mixer at Musician’s Friend. Get a low price and free shipping on. finish that gives the GigRac its tough and unique look. Amplifier Power Ratings. GigRac GigRac 1 x W @ 4 Ohms. 2 x W @ 4 Ohms. 1 x W. GigRac (W), and the £ GigRac (2xW) as tested. Setting up GigRac really is effortless and in many respects can be compared to the simple.

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This review is for educational purposes only.

Under no circumstances must 060 be attempted on the GigRac unless by a qualified technician. In 6000 review, I will be examining the finer points in gihrac electronic engineering that goes into the GigRac The PC Board in Fig 1 contains three sections. The components enclosed by the thick white line top right corner are for InRush Current Limiting. After that is the Power Supply Section lower half. Of these three, it is the InRush Current Limiting section that deserves a deeper look.

The other two are quite standard items. Fig 2 is the schematic of the Current Limiting section. Without them, the power supply, namely the power transformer and filter capacitors, will draw very high current when the GigRac is powered up.

This will in turn blow the fuse F1. A special optocoupler, a MOC, is used to control the operation of the Triac.

This is a nice touch.


Consider what happens when the GigRac suffers from a major fault, like blown power transistors in the power amplifiers. The GigRac will draw high current instantly. To protect itself, the Triac TR3 is automatically shuts off. As current flows though TH1, it will heat up. In other words, the hotter it gets, the higher the resistance. This high resistance will further reduce the amount of Mains Current from entering gigracc GigRac gigrsc The end result is No Smoke, No Fire.

The GigRac power amplifier module is exceptionally well laid out Fig 3. There are two banks of four TO-3 power transistors, one for each channel. Fig 4 — GigRac Heatsink. The GigRac is blessed with a decently sized heatsink Fig 4 to cool the power transistors. A fan is used to extract gigrrac heat away.


If purely by convection, the heatsink will be much larger. An added bonus is the fan is very silent.

This will be much appreciated by musicians. The small TO black transistor TR33 seen protruding out of the heatsink is the thermal controller that is part of the biasing circuit.

Soundcraft GigRac 600?

gograc Without this, the power transistors will soon overheat and self-destruct due to a phenomenon called Thermal Runaway. The power amplifier schematic in Fig 5 reveals some interesting ideas. Unlike most power amplifiers, the signal from the mixer enters the Inverting Input TR5 of the 1st stage differential. The signal is further amplified in the 2nd stage gigrax another differential TR23, TR Generally, a Darlington is used in the driver stage when super-beta is required.


In the GigRacthe designer opted for Sziklai instead. Sziklai offers some benefits over Darlington as they are less prone to gugrac runaway. Furthermore, Sziklai is more tolerant of pnp-npn mismatches when they are used in push-pull fashion. Fig 6 — Power Amplifier Protection Circuitry. Fig 6 is the schematic of the GigRac Protection.

Soundcraft Gigrac 2xwpc 8 Input Powered Mixer With Digital | eBay

When the heatsink gets hot, the power of the amplifier is automatically lowered. It does this by reducing the biasing current in the input differential pair.

This is quite seamless.

The difference is with a compressor, the line signal is lowered whereas over here, it is through the amplifier gain structure. When the heatsink gets too hot, TH1 shuts down higrac amplifier completely. The common method for Over Temperature Protection is to use a bimetal thermal circuit breaker on the heatsink.

Soundcraft Gigrac Mixer – USED – Nannicola Inc

However, yigrac circuit breaker can fail over time. Perhaps the designer deemed a non-mechanical solution is more reliable.

I am impressed with the GigRac It is well designed electronically and the modules within are easy to disassemble. This brand exudes quality. Soundcraft GigRac Technical Review. Soundcraft GigRac This review is for educational purposes only. The next item on the agenda is the power amplifier itself.