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Big Muff Ram's Head Violet V2 - 1st version 1973

You can find here circuits & schematics, modifications, information and error reports of some famous pedals. They are useful for reference purpose and everyone can learn much from 'em. They can also be used to build your own clone (BYOC).

Big Muff Ram's Head Violet V2 - 1st version 1973

Postby maz » January 17th, 2020, 10:44 am

The Ram's head is a legendary model of Big muff. This is the second version released after the triangle in 1973. It was then declined in lots of version up to 77, in particular the "Violet era" which sells today at almost $1000 on ebay. The rams head V2 is known to have been used by Pink Floyd guitarist David Gilmour. It was used with a boost to have an almost infinite sustain on some of its solos, like Comfortably Numb.

The Big Muff is a favorite one of pedal manufacturers. Indeed, its circuit is very well documented, simple and super easy to modify, each component plays a particular role, and changing it will have a lot of influence on the final rendering of the big muff. It is therefore easy to understand that this is one of the most cloned pedals, whether by individuals, or from well-known "boutique" brands

Technically, the big muff is not a fuzz but a distortion. However, unlike others, it has 2 successive stages of distortion, which generates the so saturated and compressed sound of the big muff, ultimately making the sound close to the sound of a fuzz.

The first section (input) is a buffer to adapt the impedance of the guitar to the first distortion stage, which also amplifies the signal. As operational amplifiers did not exist at the time of the big muff (1973), everything is done with transistors mounted as a common collector. The second and third stages (first and second clipping section) are actually exactly the same. They are used to distort the signal, we also notice the diodes that will clip the signal. First, we can see an input resistance which will slightly decrease the amplitude of the input signal, and filter the trebles a little. Then, a coupling capacitor to remove any possible DC coming from the guitar. Changing the values of this capacitor and resistance will affect the treble and bass of the big muff. Then we have a coupling capacitor followed by a resistor which will slightly modify the signal going through this saturation stage. Each transistor is mounted as a common collector, with a feedback resistor to define the bias. A 470pF capacitor will allow treble to pass by acting as a high pass filter. The fourth section is the most important, the tone stack! This small circuit is what gives the sound signature of the Big Muff, in particular its loss in medium frequencies. Finally, at the output, there is a circuit aimed at amplifying the signal cut by the diodes in order to regain volume. It is also a transistor mounted as a biased common emitter to have a strong amplification. We have a coupling capacitor at the input of this circuit, and one at the output before a potentiometer mounted in variable resistance which will allow to adjust the amplitude of the final signal.

So far, the Ram's Head Violet 1973 is one of the most popular version of Big Muff, the creamiest box of solos and walls of synaptic mythic distortions, a must for all floydian lovers. After having breadboarded lots of Big Muff versions, this is without any doubt my favorite of all.

Below are the schematic and vero layout which can be used as reference or to built your own clone of this legendary pedal. Note that the proposed schematic and layout are in respect with the original Violet Big Muff, without any power filter section and is aimed to be used on battery or with a good filtered power supply.

The Schematic :

Image

Image

:pdf: Download the complete pdf project file for direct PnP transfer, layout and schematic.

:txt: Download Bill of Materials in txt format.

Big Muff Ram's Head Violet V2 - 1st version 1973 built on Veroboard :

Image

To build this version, NPN transistors in the range of 200 hFE are prefered. The Big Muff Bias Resistors Calculator can also be used to get an estimate of all bias resistors values.

For those interested by the EHX 73 Rams Head Big Muff including a power filter section and a polarity protection, have a look at tagboardeffects

Have fun ! :)
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