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x0x:vcamods [2007/09/19 22:27]
creekree
x0x:vcamods [2016/01/28 18:05]
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-===== VCA Mods ===== 
  
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-==== Bass Boost Mod ==== 
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-This mod is absolutely essential if you want your x0xb0x to be a bassline machine. ​ It is a really good one to make!  Change C21 and C20 from .01uF to .1uF.  Some people have found that it gets too boomy if you use your x0xb0x for more of a lead sound, but you can either make it switchable or roll off the bass on your eq. 
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-{{x0x:​bassboost.png|}} 
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-==== Muffler like Distortion ==== 
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-The DevilFish has a post VCA soft-clip distortion called "The Muffler"​ that apparently retains bass response. ​ 
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-Soft clip distortion is fairly easy to set up.  You get a triple pole switch, and leave one of the poles disconnected,​ The other pole should lead to a diode going to ground. ​ The other pole should lead to a pair of diodes going to ground, one of them reverse biased. ​ The character of the distortion would change according to the diodes that you choose. ​ You could change this circuit to double up on the diodes ​ 
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-This also might make a passive filter due to C38.  ​ 
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-{{x0x:​muffler.png|}} 
-=== Choosing Diodes === 
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-From the Guitar Effects FAQ: 
-> Silicon is reputed to clip abruptly, causing a harsh sound. ​ Germanium clips at about half the voltage of a silicon diode, but is reputed to turn on more slowly in its smaller range. ​ LEDs turn on at about two silicon diode drops, and are also reputed to be slower turn on, with it and germanium giving more "tube like" sounds. ​ Some units with "​tube"​ in the title use LEDs or germanium for clipping. 
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-> Oddly enough, the Marshall JCM800 uses a set of two pairs of silicon diodes back to back as clippers. ​ This seems strange in a Marshall, but it is there. ​ When I looked at the schematic, I first thought it was a protective clamp for a tube grid, but the circuit doesn'​t work that way.  They are there for the distortion. 
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-If you perform this mod, please post your experiences with it! 
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-CategoryMods 
/home/ladyada/public_html/wiki/data/pages/x0x/vcamods.txt · Last modified: 2016/01/28 18:05 (external edit)