MK-1 Preamp Anatomy (EQUALIZER PERFORMANCES)

The complete reverse engineering of the equalizer section of the MK-1 is the following:

Once more:

• The Bass & Treble controls are sharing the same active Baxandall stage with possible undesird interactions
• The Mid control is using a separate stage not interacting with Bass & Treble

Review

What's the best and fast method for demonstrate the MK-1 is a bit ... weird ?

To make a very long story short using a very direct and intuitive example.....let's imagine to grab Our bass and roll for a 1\4 turn clockwise both BASS & TREBLE controls....

This is a typical setting for amplify a bit both the edges of the bass audio spectrum...

Le't forget about the MID control for the time being..

What You may expect to see the graphs is:

• A descending slope on the  BASS-leftside

• A small valley in the MID-dle area 

• An ascending slope on the TREBLE-rightside

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..
...
....
.....
......

The reality is instead the FOLLOWING:

More that an equalization curve  .....this looks like a flat PIZZA more or less levitating over 4Db........reference line........   :-(

THIS undesired behaviour is due to the excessive interaction between bass & treble controls.... as We can easily understand looking at the consistent common area  underlined in light blue:

Just for reference  We can give a look at the specs  of other well known bass Preamps:

We can see both of them trying to minimize the COMMON INTERACTION AREA and this is one of the 1st goal of the modifications We Will perform in the next posts.
We can also see the EXCESSIVE power of the Treble control that is way too much invasive. Basically this is acting as a kind of volume control instead of a proper treble filter... 



In the next posts We will see how to modify  the MK-1 in a way to achieve a more nice and effective equalization and a better tone definition.   

We will start with the 1C-MOD , the most easy mod possible in the universe of the mods.








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