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Dropping the bass - love at 50Hz

Hertz

Hertz

May 17, 2014
261
251
56
Aurora, Colorado
#1
I have been looking for ways to control low end in my rig. I tried compressors, processors, pedals, cabinets etc. I finally found a cab and speaker combo that I really like but still struggled to control the low end. 80Hz roll offs just don't do it for me unless I am really cranked.

I decided to make my own high pass filter. Just a fixed HPF at 50Hz. I tried several values starting at 30Hz and moving up until I found the sound. I know that a lot of HPF have variable frequencies that you can adjust to match your rig. I only have one rig with a backup head so I know what my cabinet is capable of and what sounds best for me.

If you are interested in trying this yourself:

Find out what your cabinet is rated for in terms of frequency response most will be around 50Hz some more some less.

Go to High Pass Filter Calculator

Enter the desired lowest frequency value your cab can handle at say 96db and a capacitor value say 47nF.

press enter and this web page with give you the resistor value needed. Try a few frequencies and then order your parts. The wiring diagram is at the top of the page with the lower line being ground and the upper hot/ positive/ Tip.

I purchased a bread board for testing along with 2 1/4 jacks and hookup wire so that I could try a few frequencies. No batteries needed. Soldering is required once you find the frequency.

Now I can play loud and use the amps bass tone control maxed if i want and not have to worry so much about speaker excursion (AKA farting Out the Speaker). I do however recommend using your eyes and ears when adjusting the bass knob on your amp.

I thought this might help you guys with pedal boards trying to control the rest of your rig.
 
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#3
Rambazamba said:
That's very interesting. Where would you place the HPF? Between bass and effects, effects and amp or in the loop between preamp and poweramp? Or maybe use multiple HPFs?
Click to expand...

Right after your bass. You can even install this filter in your control cavity with a switch to bypass it if you prefer. I boxed mine.
I have no effects. Knob twiddling drives me crazy but I have respect for people who can handle so many option.
 
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#4
I played around with the calculator and eventually came up with this drawing for a variable high pass, going from approximately 25Hz to 105Hz cutoff frequency. I ordered the parts and hope to assemble it over the weekend. Can't wait to test it!
20170405_093726.jpg
 
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#5
Nice. Does that say 100nF and 15k ohm? When I was prototyping my frequency cutoff I discovered that capacitors in series will decrease the overall capacitance. For instance I had a 47nF cap after an 11nF cap and the resulting capacitance was 9nF. At 100 ohms of resistance this put me somewhere around 187Hz. Too high but sounded cool, like a telephone effect.

For anyone that is interested see capacitors in series example number 1.
Invalid Link Removed

Cant wait to hear about your variable circuit.
 
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#8
Hertz said:
Francis is a genius and has a lot of great info including schematics of his own devices.
Click to expand...
+1...his HPF-Pre Series 3 is an exceptional design. It works well in an effects loop or right after the bass before the amp input and is dead quiet - no added noise at all. I bought two of them and they are easily one of the most useful tools I've ever owned. I always have one in my gig bag.
 
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#10
Rambazamba said:
I played around with the calculator and eventually came up with this drawing for a variable high pass, going from approximately 25Hz to 105Hz cutoff frequency. I ordered the parts and hope to assemble it over the weekend. Can't wait to test it!
View attachment 1098418
Click to expand...

I hope you do this! I'm interested in something like this, DIY.
Please post your experience and pictures if you are able.
 
#11
Hertz said:
Nice. Does that say 100nF and 15k ohm? When I was prototyping my frequency cutoff I discovered that capacitors in series will decrease the overall capacitance. For instance I had a 47nF cap after an 11nF cap and the resulting capacitance was 9nF. At 100 ohms of resistance this put me somewhere around 187Hz. Too high but sounded cool, like a telephone effect.

For anyone that is interested see capacitors in series example number 1.
Invalid Link Removed

Cant wait to hear about your variable circuit.
Click to expand...
If you want to add capactance, you wire in parallel. In series they work like parallel resistors as far as the math. So you dont need a huge selection to come up with a lot of values for caps or resistors, which is nice.
 
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#12
So. Parts arrived this morning, I did the build in the afternoon and went to the practice room. First I put it in the fx loop of my amp. It worked good but I could as well get the same effect by rolling down the bass on the amp itself. So I put it right after my bass. I could not put it between effects and amp, because I split the signal in wet and dry paths using the 2 inputs of the amp.
But the position between bass and pedals seems to be the best anyways - it also tightens up all the fuzzes and filters which is really great. The cutoff frequency range from 25 to 105Hz is perfect for my taste, I set it at around 40Hz though. I now have to test it with the full band but am very happy already. You should build one, too.
 
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#14
Rambazamba said:
So. Parts arrived this morning, I did the build in the afternoon and went to the practice room. First I put it in the fx loop of my amp. It worked good but I could as well get the same effect by rolling down the bass on the amp itself. So I put it right after my bass. I could not put it between effects and amp, because I split the signal in wet and dry paths using the 2 inputs of the amp.
But the position between bass and pedals seems to be the best anyways - it also tightens up all the fuzzes and filters which is really great. The cutoff frequency range from 25 to 105Hz is perfect for my taste, I set it at around 40Hz though. I now have to test it with the full band but am very happy already. You should build one, too.
Click to expand...

Awesome! Snap a picture of yours if you can, please. Inside, also. Thanks!
 
#17
Hertz said:
Here is a picture of mine. Using parts I had laying around and boxed.View attachment 1103086
Click to expand...

Thanks for posting these, can you possibly post a pic of the underside of that board too?

And for both you and @Rambazamba , if you have time could you post a parts list? I think I follow the diagram but I get a little confused with this stuff. I definitely want to try it out though. No rush, only if you have time. Thanks!
 
#18
Rambazamba said:
I played around with the calculator and eventually came up with this drawing for a variable high pass, going from approximately 25Hz to 105Hz cutoff frequency. I ordered the parts and hope to assemble it over the weekend. Can't wait to test it!
View attachment 1098418
Click to expand...

Thanks for this schematic and diagram.


Is R1 pinout 3 2 1 (top to bottom) looking at the back of the pot?
 
#20
Rambazamba said:
I played around with the calculator and eventually came up with this drawing for a variable high pass, going from approximately 25Hz to 105Hz cutoff frequency. I ordered the parts and hope to assemble it over the weekend. Can't wait to test it!
View attachment 1098418
Click to expand...

@Rambazamba What did you use for the switch? DPDT?
 

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