Passive HPF with set frequency?

[sokolasty]

Hi


I had for few days a Harley Benton Progressive active bass. I tried to adjust the bass and treble without battery and it worked as a cutter.

This made me think?
Can one use single induction coil to cut off the lows?
Will this work as HPF with fixed frequency and adjustable "strength", just like capacitor cuts highs?
What would be the coil for like 60 Hz?

 

[fig]

Can one use single induction coil to cut off the lows?
Will this work as HPF with fixed frequency and adjustable "strength", just like capacitor cuts highs?
What would be the coil for like 60 Hz?

Using an inductor and doing the math is beyond me currently. That's because my deeper level learning is over 40 years old LOL.

However, there is an alternate passive bass cut that has a fixed frequency, and has been used in G&L basses and some folk in the forum. Consists of a pot and cap.

A passive treble tone control is connected in parallel with the main signal path. The passive bass cut is connected in series, along the main signal path.

Here's a G&L schematic of their L-1000 bass. Has the treble cut and bass cut (both highlighted) in one circuit. Notice that the bass cut pot and cap have unusual values. 1MegΩ for the pot and 0.0022uf for the cap. Probably a good starting set of values, change values to fit your needs.:

With the bass cut pot at one extreme (wiper arm to the right), the cap and 1MegΩ resistance get shorted out (electrically doesn't exist anymore), allowing the full audio spectrum (Bass, Mids, Treble) to the volume control. With bass control pot at other extreme (wiper arm to the left), Bass and Mids are blocked (by 1MegΩ) while the cap only allows Treble to the volume control. Between extremes, adjustable strength.

Not what you're specifically asking about regarding using an inductor, but thought I'd throw it out to you.

 

[Matt Liebenau]

Using an inductor and doing the math is beyond me currently. That's because my deeper level learning is over 40 years old LOL.

However, there is an alternate passive bass cut that has a fixed frequency, and has been used in G&L basses and some folk in the forum. Consists of a pot and cap.

A passive treble tone control is connected in parallel with the main signal path. The passive bass cut is connected in series, along the main signal path.

Here's a G&L schematic of their L-1000 bass. Has the treble cut and bass cut (both highlighted) in one circuit. Notice that the bass cut pot and cap have unusual values. 1MegΩ for the pot and 0.0022uf for the cap. Probably a good starting set of values, change values to fit your needs.:

View attachment 5463508

With the bass cut pot at one extreme (wiper arm to the right), the cap and 1MegΩ resistance get shorted out (electrically doesn't exist anymore), allowing the full audio spectrum (Bass, Mids, Treble) to the volume control. With bass control pot at other extreme (wiper arm to the left), Bass and Mids are blocked (by 1MegΩ) while the cap only allows Treble to the volume control. Between extremes, adjustable strength.

Not what you're specifically asking about regarding using an inductor, but thought I'd throw it out to you.

Also note the bass cut pot is a “C” taper which, I believe, is antilog or reverse audio taper?

 

[fig]

Also note the bass cut pot is a “C” taper which, I believe, is antilog or reverse audio taper?

I had to hunt for that one LOL

 

[Will_White]

Also note the bass cut pot is a “C” taper which, I believe, is antilog or reverse audio taper?

A linear pot works ok too, but I've found it works best all the way on with whatever taper you choose, so a 3 position switch actually works better. You can have one small cap and one larger to shift the cut-off frequency .0047or .0033uf and .01uf are what I usually use.