I've had a 2004 USA-made Music Man SUB Sterling for a few years now. I never quite liked the sound of it as much as the 2EQ Stingray version of the same guitar, but I was never fortunate enough to find one when they were still affordable. Recently, I came across a Youtube video comparing the sound of a 2EQ and 3EQ which explains why the two preamps do not sound like one another.
With the help of some research and a bit of chatGPT, I found a way to modify my circuit to bring the sound of my bass a lot closer to that of a 2EQ model. I am not particularly knowledgeable in circuits but I do know how to solder so I went ahead and made the changes. It seems to have had the effect I was looking for, although I don't have a 2EQ on hand I can compare it with.
Here are all the changes I made and what effect I believe them to have had on the sound:
- The two 8.2n coupling capacitors by the input were changed to 100n, as those are responsible for the high pass filter, which would cut frequencies below ~75Hz. Now the HPF starts at 10Hz
- The 2.2n input to ground cap (top-left), is supposedly the cause of the treble spike on the 3EQ that occurs around the 4-10KHz range regardless of the treble knob position. The new 470p cap should now flatten this.
- The change bass cap change from 68n to 100n should have allowed the bass knob to now control deeper frequencies than before.
- The bass resistor change from 6.8k to 4.7k should have increased the boost/cut intensity that the knob provides. The bass output resistor was also changed to match the input resistor.
- The mid cap change from 4.7n to 2.2n should have shifted the mid frequency response toward the upper mids rather than lower.
- The mid resistor change from 3.9k to 6.8k should have flattened out the strength of the mid knob.
- The treble cap change from 2.2n to 3.3n should have extended the treble range slightly higher.
- The treble feedback capacitor (on the right), changed from 100p to 150p should have smoothed out some of the extreme treble for a more warm sound.
I've attached my schematic with the modifications in red. If anyone more experienced than me has any input or corrections to what I included here, please chime in!
With the help of some research and a bit of chatGPT, I found a way to modify my circuit to bring the sound of my bass a lot closer to that of a 2EQ model. I am not particularly knowledgeable in circuits but I do know how to solder so I went ahead and made the changes. It seems to have had the effect I was looking for, although I don't have a 2EQ on hand I can compare it with.
Here are all the changes I made and what effect I believe them to have had on the sound:
- The two 8.2n coupling capacitors by the input were changed to 100n, as those are responsible for the high pass filter, which would cut frequencies below ~75Hz. Now the HPF starts at 10Hz
- The 2.2n input to ground cap (top-left), is supposedly the cause of the treble spike on the 3EQ that occurs around the 4-10KHz range regardless of the treble knob position. The new 470p cap should now flatten this.
- The change bass cap change from 68n to 100n should have allowed the bass knob to now control deeper frequencies than before.
- The bass resistor change from 6.8k to 4.7k should have increased the boost/cut intensity that the knob provides. The bass output resistor was also changed to match the input resistor.
- The mid cap change from 4.7n to 2.2n should have shifted the mid frequency response toward the upper mids rather than lower.
- The mid resistor change from 3.9k to 6.8k should have flattened out the strength of the mid knob.
- The treble cap change from 2.2n to 3.3n should have extended the treble range slightly higher.
- The treble feedback capacitor (on the right), changed from 100p to 150p should have smoothed out some of the extreme treble for a more warm sound.
I've attached my schematic with the modifications in red. If anyone more experienced than me has any input or corrections to what I included here, please chime in!
