Question about understanding / using a High Pass Filter

[SOUTH PAW]

so, after reading through recent threads on the subject, I have gone from a casual interest in buying a hpf ( Broughtont ) to a real GAS buildup for one. The only thing in my understanding ( or lack of ) that I want to be clearer or cleared up first is, in order for it to fully have control over the low frequencies it's set to high pass, say for example, with a pedal board in front of a bass amp, wouldn't it have to be after everything in the signal chain? Even the preamp in the bass amp itself? .....I ask, because, a few times in one of the threads, it was mentioned to place it first in the chain, but was never elaborated on. That got me wondering what I'm missing.

Thanks, SP

 

[Downunderwonder]

Not so many fx add low end. Unless yours do, you are good either end.

 

[pfschim]

reading the HPF/LPF mega thread is very helpful (if you have not already done that).
I think most people are using their HPF after everything outboard of their amp/cab, but I have read some alternative signal chain placements.
You should maybe start with it before your Bass signal hits the amp input, but then you can try it anywhere in your signal chain. Can't hurt to try. I have mine (fdeck v3) after all my outboard stuff, before it hits the amp input ... works fine there. I have also tried mine in various amp FX in/out sections ... a bit different operation, but also works ok there too.

Also keep in mind, depending on your amp, it may have a built in HPF or limiter, so try and find that out because using multiple HPF's can be a gamble as far as noise in your signal chain and possible unintended cuts in your targeted low freq range.

great devices, well worth checking out.
good luck.

 

[BurningSkies]

I've always had mine at the end of my chain right before my amp setup. That way any effects that might create content deep down still get caught by the HPF.

 

[Wasnex]

so, after reading through recent threads on the subject, I have gone from a casual interest in buying a hpf ( Broughtont ) to a real GAS buildup for one. The only thing in my understanding ( or lack of ) that I want to be clearer or cleared up first is, in order for it to fully have control over the low frequencies it's set to high pass, say for example, with a pedal board in front of a bass amp, wouldn't it have to be after everything in the signal chain? Even the preamp in the bass amp itself? .....I ask, because, a few times in one of the threads, it was mentioned to place it first in the chain, but was never elaborated on. That got me wondering what I'm missing.

Thanks, SP

Unfortunately there is no universal correct answer. It depends upon your signal chain and how you are trying to manipulate your signal. Running an HPF in the Effect Loop would do what you propose. Just make sure the HPF is compatible with the signal level of the effects loop.

 

[Omega Monkey]

Well, if you spend the money on a HPF, you're not likely to go and dime the bass on your amp, right? So if your amp is set relatively "flat", it should just be passing through whatever signal comes into it. If that signal has been high passed already, there you go.

But really, where you put it in the chain kind of depends on where else you put it in the chain. If you have octave, filter, and synth effects that are adding low end, you probably want to put it after those, but if you have distortions or fuzzes that or anything else that taking away low end, you probably want it before those. Depending on what all is in your chain, you may have to compromise on signal flow and HPF placement to get something that works well and makes sense. It will also act differently before or after compression (or more accurately, the compression will act differently).

 

[SOUTH PAW]

Oh okay, yes, I do have a couple that do, so with that setup, I would place it at the end. C

Not so many fx add low end. Unless yours do, you are good either end.

Oh okay, yes, I do have a couple that do, so with the pedal board setup, (I also have other ones) I would place it at the end. Thanks

 

[SOUTH PAW]

Thanks, all great answers that tell me there are a lot of options in where to place depending on what I'm using and what my goal is, as opposed to rendering it useless if not used a certain way. Cool, so far no

 

[Passinwind]

Well, if you spend the money on a HPF, you're not likely to go and dime the bass on your amp, right?

I wouldn't be too sure of that at all.

 

[BurningSkies]

I wouldn't be too sure of that at all.

You rang?

 

[SOUTH PAW]

Unfortunately there is no universal correct answer. It depends upon your signal chain and how you are trying to manipulate your signal. Running an HPF in the Effect Loop would do what you propose. Just make sure the HPF is compatible with the signal level of the effects loop.

I was already thinking of using the effects loop on the amps that have one, so it would filter any unwanted mud and otherwise wasted energy, while helping the speaker's out as well. That was as far as I got on my own, without having yours, and others level of knowledge to know how it could really work any other way. I was stuck at the idea, that anything that could boost the lower frequencies, including the amps preamp, to where there's too much mud, would effectively defeat its ability to control them, if it didn't come after. While if all of that is true, it would mean that most of what is being high pass filtered, is the bass guitar itself. Am I correct, or sounding more confused?

 

[Downunderwonder]

I think you have started way over thinking it. Just put it at end and crank it up until it sounds weak and let it off until it doesn't. If the speakers still complain or the room is out of control booming back at you then adjust bass control or HPF a little at a time until all is good again.

 

[SOUTH PAW]

I wouldn't be too sure of that at all.

Rest assured, I'm conservative in everything I do. Haven't blown a speaker yet, and even hate the sound of one that's straining.

 

[Passinwind]

Rest assured, I'm conservative in everything I do. Haven't blown a speaker yet, and even hate the sound of one that's straining.

Cool, but my comment reflects that one nice byproduct of using a good HPF is that you actually can often times boost your amp's or onboard preamp's bass control a lot and still get useful results.

On my own DIY amps I've settled on situating the HPF just before the power amp section. That allows me to HPF whatever I use my Aux/EFX Return input for. There's more than one way to skin felis catus, for sure.

 

[SOUTH PAW]

I think you have started way over thinking it. Just put it at end and crank it up until it sounds weak and let it off until it doesn't. If the speakers still complain or the room is out of control booming back at you then adjust bass control or HPF a little at a time until all is good again.

I probably have, ( thanks TB for informing me beyond my intelligence ) but by having thought about it, you were able to give a simple summary of what to do.

 

[Tim Skaggs]

I understand the stated purpose for using a HPF is to keep sub-audible low frequencies out of the amp section so it won't be wasting power by trying to amplify those super low frequencies. It also keeps super lows from being pushed by the amp into the speaker, possibly causing causing speaker distortion from the speaker trying to reproduce those sub-audible freqs.

So, HPF definitely before the amplifier, and probably before the preamplifier also.

 

[jmlee]

If you have an octave pedal in your chain which synthesizes notes an octave down you definitely want the HPF at the end of your chain.

 

[Wasnex]

I was already thinking of using the effects loop on the amps that have one, so it would filter any unwanted mud and otherwise wasted energy, while helping the speaker's out as well. That was as far as I got on my own, without having yours, and others level of knowledge to know how it could really work any other way. I was stuck at the idea, that anything that could boost the lower frequencies, including the amps preamp, to where there's too much mud, would effectively defeat its ability to control them, if it didn't come after. While if all of that is true, it would mean that most of what is being high pass filtered, is the bass guitar itself. Am I correct, or sounding more confused?

If the HPF is before the bass tone control there is no super low frequencies to turn up.

If the HPF is after the tone control, it cuts the low frequency after you have turned it up.

It works slightly different in each position. For example if you place it after the tone control, when you turn up the bass you may overdrive the next stage of amplification; perhaps this is desirable. If you place the HPF before the tone controls you may not get the overdrive, or the quality of the overdrive may be different. This is what I mean by "It depends upon your signal chain and how you are trying to manipulate your signal."

 

[40Hz]

All depends on where you want to cut your lows - and why.

Effects in serial signal chains are additive. That means each stage affects everything downstream from it as @Wasnex alluded to in the above post.

In the case of a HPF, if you wanted to eliminate any frequencies your amp and cab probably can't reproduce, then the most effective position for it is just before your signal hits the power amp stage. So yes, by itself in the effects loop (assuming the effects loop is a serial rather than a parallel loop) is the logical place to put it if that's your goal for using a HPF. And for most people, most times it will be.

 

[SOUTH PAW]

Just to be clear, my applications for it varies quite a bit. A number of combo amps, heads, cabinets, and some both with and without individual pedals / multi effects or my pedal board. Also, a number of different basses...active, passive, solid body, acoustic at Home,rehearsal, Church, Coffe House, outdoor fairs.

So anything but a singular use, but seems like a single tool for any situation.

My most recent application would have been with a small 45 watt 10" combo amp and violin bass, against two acoustic guitars and vocals through a couple of powered speakers ( 210 + 112 ). I was using a Zoom MS bass pedal that I was wishing had a hpf pedal choice. Every time I would get the sound I wanted at the necessary volume, it would just start to strain the speaker.