Mod to Mercurial Boost

[waaaaaark]

How simple would it be to modify the Mercurial Boost's frequency range? I'd like it to go up to about 4k.

Thank you

 

[Aleph Null]

Looks like you'd have to reduce C2 and C3, to 6.8nF and increase R7 and R8 to 5.6k. That gives you an upper frequency of 4.2kHz. The Frequency control will have to be increased to allow you to get down to the same low frequency. 250k gives you a low of 92Hz. 500k would go all the way down to 46Hz

 

[waaaaaark]

Looks like you'd have to reduce C2 and C3, to 6.8nF and increase R7 and R8 to 5.6k. That gives you an upper frequency of 4.2kHz. The Frequency control will have to be increased to allow you to get down to the same low frequency. 250k gives you a low of 92Hz. 500k would go all the way down to 46Hz

Thanks so much! For my own curiosity, how did you calculate this?

 

[Aleph Null]

I used an app call "Electrodoc Pro" to do the math for me, but you can use the equation for RC filters. I fiddled around with common values to see what got closest. As to knowing which components to change, that just comes from staring at schematics for years.

To be clear, this is an educated guess; I don't have hands on experience with this particular circuit. If it were me, I'd probably breadboard it to see what it sounded like, or build the board with sockets to test values. I routinely find that the cutoff frequency that sounds best isn't what I would have initially guessed.

 

[jwin615]

I used an app call "Electrodoc Pro" to do the math for me, but you can use the equation for RC filters. I fiddled around with common values to see what got closest. As to knowing which components to change, that just comes from staring at schematics for years.

To be clear, this is an educated guess; I don't have hands on experience with this particular circuit. If it were me, I'd probably breadboard it to see what it sounded like, or build the board with sockets to test values. I routinely find that the cutoff frequency that sounds best isn't what I would have initially guessed.

Check out Caltronics. I paid for EDP but moved to using Caltronics after trying it a couple years ago after my Pro license disappeared. The added filter calcs are nice.