Please review the site Rules, Terms of Service, and Privacy Policy at your convenience. Rules, TOS, Privacy
Get familiar with the reaction system: Introducing the Reaction System

Sub amp HP/rumble filters

Is there a compiled list of subwoofer amp HP filters? I'm looking for something in the mid 20's range.


  • Not that I'm aware but FWIW the sub amp frequency response can be easily measured with that ARTA jig, and input op-amp circuitry is generally quite simple and usually easily modifiable to suit your needs.

    I'm not deaf, I'm just not listening.
  • The Bash amps have a chart with resistor values so they can be changed to suit one's needs.

  • I've done that with Bash amps, are others as easy to modify?

  • Reid, you've been inside my Dayton 240. Did that look like it could adjusted?

  • Of course, I actually still have it here, forgot to give it back to you the last time you were at my place. That amp is toast so I'm not sure if you want to keep it. The input board is just a single sided board with some op-amp circuits on it. All through hole stuff here. With a little bit of time it can be drawn out, simulated and modified.

    Wish I could get my SVS Bash amp working properly, that one has a little op-amp daughterboard with a selectable high pass filter.

    I'm not deaf, I'm just not listening.
  • I wondered where that went. I was going to rob something off it so I should grab it next time.
    What do we need to do to create a selectable HP like that? That looks handy.

  • edited December 2021

    Wouldn't take much, it's just a single op-amp circuit connected to a rotary switch. You could build the circuit on one of those little prototyping breadboard pcbs, and hack it into whatever you need, just need power which on a plate amp you can tap into whatever power supply is already there.

    Here's a closer look at the PCB in the bash. Looks like I already did a modification to it some years ago when I got the amp. If I recall, the stock filters had a bit of high Q peaking depending on which one was selected.

    Here's a basic circuit. You can plunk this into VituixCAD yourself and play around with the values of the two resistors there. Then its just a matter of providing a switch to select various resistors in the circuit. Place two of those circuits in series for a 4 pole filter.

    I'm not deaf, I'm just not listening.
  • Ha. I didn't expect you to dissamble an amp and create a circuit. It is Christmas day after all:)

  • I just took out 2 screws and took some photos, the circuit isn't an extensive reverse-engineering effort, it's just copy-paste from searching the internet for "subsonic filter circuit", but it's basically what is on that board. Not much excitement for Xmas this year, our family is far away and we didn't travel, so I don't really have much better things to do ;)

    I'm not deaf, I'm just not listening.

  • This the HP circuit I used on a bass guitar pedal.

  • What is the cutoff point in that circuit?

  • Adjustable by the 50k pot.

    I'm not deaf, I'm just not listening.
  • edited January 4

    Honestly I never did the math, it was from a schematic for a HP guitar pedal that I incorporated into another circuit for blending two signals together. It said 20-200Hz

Sign In or Register to comment.