Tuesday, March 25, 2014

Updated Components Continued

The amp was way too quiet for my tastes, so I made two more changes. First, I took out R7. This value was originally 1 Mega ohm, but I changed it to 100 kilo ohm. Now it is nonexistent.

Originally, R2 was 68 kilo ohm, but I lowered it to 47 kilo ohm originally. Next, I lowered the value of R2 down to 10 kilo ohm.

Below is a schematic of the Valve Jr, Version 2. Ignore those arrows, that isn't my work. As you can see R7 was used to bring the signal down, as it goes straight to ground. This is useless for what I want, so it is gone.

R1 and R2 are in parallel on the guitar input jack. Since I changed R1 from 68 kilo ohm up to 1 Mega ohm yesterday (HUGE INCREASE), I decreased R2 much more. Since R2 is actually before R1 in the circuit, it creates a voltage divider which decreases the signal right when you plug in your guitar. Making R2 smaller will give less signal loss. One modification option I have in the future is to move R1 in front of R2 in the circuit, which would decrease the voltage divider even more. 

Un-modded Valve Jr Version 2.


The results? Sounds incredible. The amp can get loud again, which is what I wanted, and the mellow sounds when you turn the tone pot down on the guitar and use a neck pickup is incredible. I love this amp and the way it sounds so far. I have been working on my pedal board at home, and I'll bring that in next week to play some pedal through the amp. I haven't played anything but clean on it so far.

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