High pass filter : frequency?

[dave_anderson]

I'm not sure why you would want to use an HPF on a bass guitar?
The fundamental of a low E is 41.2Hz and 31Hz for a low B. If you take that away you're losing all the definition and energy.
Engineers deal with that out front or in the studio. Send them a full range signal and relax.

 

[Nashrakh]

I'm not sure why you would want to use an HPF on a bass guitar?
The fundamental of a low E is 41.2Hz and 31Hz for a low B. If you take that away you're losing all the definition and energy.
Engineers deal with that out front or in the studio. Send them a full range signal and relax.

I don't know man, my rehearsal room doesn't come with an engineer.

 

[el murdoque]

This might seem like a "duh, obvious" statement, but if your cabinet only goes down to 50hz, you're not going to hear any difference from a HPF at 40hz. If you want to hear the HPF actually "doing something" it has to be within the frequency range of your cabinet.

This is the complete opposite of a "duh, obvious" statement.
You will hear a (significant) difference between a HPF at 40Hz and no HPF when you feed a 20Hz signal into a cabinet that only 'goes down' to 50hz.
A standard cabinet will not cut off the frequencies below 50Hz with a hatchett. It will try to do them, but the curve is falling off. The 50Hz is the point where it reaches -3dB for the serious brands and -6dB for the less serious ones.

So your cabinet does not ignore everything below 50Hz. It tries to do it, but cannot do it as loud as the rest.
Using a HPF in that scenario can be a great relief for the cabinet.

 

[dave_anderson]

I don't know man, my rehearsal room doesn't come with an engineer.

The signal you're producing is not the issue. Treat the room. You may as well use a guitar imo if you're taking away all the low end and in Particularl the fundamentals below A string.

 

[J.Wolf]

The signal you're producing is not the issue. Treat the room. You may as well use a guitar imo if you're taking away all the low end and in Particularl the fundamentals below A string.

Just tell that dive bar they need to spend a few thousand to treat the room properly, so the bass can sound correct. Or, like most of us, get an HPF and find substantial improvement on your own.

 

[J.Wolf]

I'm not sure why you would want to use an HPF on a bass guitar?
The fundamental of a low E is 41.2Hz and 31Hz for a low B. If you take that away you're losing all the definition and energy.

I think many of us here would disagree with you, based on thousands of collective hours of experience that would seem to indicate otherwise.

Engineers deal with that out front or in the studio. Send them a full range signal and relax.

Many people are playing in smaller rooms without FOH support for the bass. And, to take it a step further, many of us play in settings with FOH people who are less than optimal, and the more I can do to tailor my signal the better. Sometimes I get a great soundman, often I get whoever is working, and the dude cant be bothered. So I "help him help me" by doing the compression, EQ/HPF etc. that I know is going to be needed.

 

[monsterthompson]

So your cabinet does not ignore everything below 50Hz. It tries to do it, but cannot do it as loud as the rest.
Using a HPF in that scenario can be a great relief for the cabinet

This is observable. If you plug in a bass and crank up the amp, then pinch and slowly wiggle a string at a subsonic frequency, the driver(s) in the cab can be seen moving.

 

[misterCRUSH]

Been said, but go with your ears. Mine setting changes with every bass, cab config, type of music, and room. Even placement of your rig in a room can be helped by a good HPF setting. I.E. I had no choice but to put my cab in a corner at recent show. Changing the HPF to about 115hz really helped (ported cab). Hope this helps!! BASS.

 

[DrThumpenstein]

I posted earlier in the thread about how useful the HPFs on my amps are to dial in a good aggressive tone, but I neglected to answer your actual question about where it's set. The HPFs in question (Mesa TT800 and WD800) are adjustable from 25-125 Hz. For a rock/metal mix, I usually have it up ~60-70 Hz, which really helps emphasize the mids, critical in a rock mix. For reggae, I usually leave it down ~30-40 Hz, and go higher if needed for the room. Our PA has two 18-in subs and 15-in mains (with the crossover set ~100, I think) and I always send a post-EQ signal.

I'd again emphasize that these are not hard cutoff points, so there is still 40 Hz signal coming through when I have it at 60, just not as much. With these particular amps, there is interplay between the other EQ controls and the HPF, so some unique voicings are available by exploiting the HPF in combination with the Bass control (and Deep switch on the TT) and other EQ controls. People hear second harmonics much more than the fundamentals, and ultimately, it's the whole mix that matters.

I set it higher at band practices, when I'm playing through an ancient, thunderous Ampeg 215 cab, than I have it set with my Subway cabs, because it tightens up the looser low end in that Ampeg cab.

I were ever to get an amp that didn't have an adjustable HPF, I'd throw a Broughton or something in the chain. It's an indispensable tone tool.

 

[djmay]

This is the sound of the instrument through an Alembic SF-2 Superfilter HPF. As mentioned earlier the HPF cutoff is 110 with a 7db boost at the cutoff frequency. There is no amp and no effects. The signal chain is bass > SF-2 > DI > FOH.

 

[sunbeast]

This is the complete opposite of a "duh, obvious" statement.
You will hear a (significant) difference between a HPF at 40Hz and no HPF when you feed a 20Hz signal into a cabinet that only 'goes down' to 50hz.
A standard cabinet will not cut off the frequencies below 50Hz with a hatchett. It will try to do them, but the curve is falling off. The 50Hz is the point where it reaches -3dB for the serious brands and -6dB for the less serious ones.

So your cabinet does not ignore everything below 50Hz. It tries to do it, but cannot do it as loud as the rest.
Using a HPF in that scenario can be a great relief for the cabinet.

Not to mention you are wasting a ton of power amplifying fundamentals and lower sub noise that your cab can't really project efficiently anyway.

 

[sunbeast]

I'm not sure why you would want to use an HPF on a bass guitar?
The fundamental of a low E is 41.2Hz and 31Hz for a low B. If you take that away you're losing all the definition and energy.
Engineers deal with that out front or in the studio. Send them a full range signal and relax.

The 2nd harmonic of those low notes is where the most energy is, most of us aren't playing through cabs (or even headphones for that matter) that can actually put out much volume at those low fundamentals (and trying to do so is a lot of work for the speakers and wastes significant amplifier power), and for many types of music actually amplifying those low fundamentals significantly would turn the mix to mud and step all over the bass drum. There is a lot of modern music where bass (in particular synth bass) might have a lot of energy in the actual sub frequencies, but still plenty of music where that wouldn't even be desirable. By the same token, most guitar (particularly overdriven to any degree) is highly focused on the midrange area and there is plenty of room for the bass in between a guitar and bass drum in a mix.

Not to mention none of these filters are brick walls- a 12db/octave filter set at 40hz is still letting through most of your 40hz frequencies

 

[dave_anderson]

Having been a working musician for about 35 years, studio and live Engineer for 30 years, an acoustician for 25 years I think I'm more than qualified and experienced to reiterate my comments. You are going about this the wrong way. If you don't know how to EQ a rig or instrument for a room, removing fundamentals and bottom end from your signal does not solve the problem.
Let me give you an analogy of that 'solution'
'I've got an itchy foot, ok I'll cut my leg off. Problem solved!'

I think many of us here would disagree with you, based on thousands of collective hours of experience that would seem to indicate otherwise.

Many people are playing in smaller rooms without FOH support for the bass. And, to take it a step further, many of us play in settings with FOH people who are less than optimal, and the more I can do to tailor my signal the better. Sometimes I get a great soundman, often I get whoever is working, and the dude cant be bothered. So I "help him help me" by doing the compression, EQ/HPF etc. that I know is going to be needed.

 

[sloppy_phil]

Having been a working musician for about 35 years, studio and live Engineer for 30 years, an acoustician for 25 years I think I'm more than qualified and experienced to reiterate my comments. You are going about this the wrong way. If you don't know how to EQ a rig or instrument for a room, removing fundamentals and bottom end from your signal does not solve the problem.
Let me give you an analogy of that 'solution'
'I've got an itchy foot, ok I'll cut my leg off. Problem solved!'

I mean, you are certainly welcome to reiterate your comments. And I have no doubt you are experienced; that's a lot of time spent in the field. But I'd humbly suggest there is quite a difference between stating your opinion, and providing objective facts. You are providing your findings. Others have provided their findings. This should be a place to discuss! Disagreement is critical to debate, but I'd also argue there's being constructive/helpful, and then there's being a bellend. Don't be a bellend.

 

[agedhorse]

I would also like to add that a HPF is NOT the right tool for fixing issues with boomy, standing waves in rooms. This seems to be a very common misconception.

In very large rooms, it's often the most effective tool even if it's not the bast. Removing some LF energy can give the perception of an improvement even if there's no practical way to (really) fix it.

 

[J.Wolf]

Having been a working musician for about 35 years, studio and live Engineer for 30 years, an acoustician for 25 years I think I'm more than qualified and experienced to reiterate my comments. You are going about this the wrong way. If you don't know how to EQ a rig or instrument for a room, removing fundamentals and bottom end from your signal does not solve the problem.
Let me give you an analogy of that 'solution'
'I've got an itchy foot, ok I'll cut my leg off. Problem solved!'

I guess Mesa, GK, Darkglass, Aguilar, markbass, acoustic image and others are just as dumb as me, since they have built in HPF's in their heads. And we all know how unpopular and terrible sounding their stuff is.

if the HPF'ing solution is cutting off an itchy leg, I suppose "treating a room" you don't own or have control over (ie every gig ever) is like trying to deal with your itchy leg by telling all of your neighbors and everywhere you go in public that they need to remove all poison ivy and mosquitos, so that your leg can stop itching. Lol

 

[Isaac_James]

In very large rooms, it's often the most effective tool even if it's not the bast. Removing some LF energy can give the perception of an improvement even if there's no practical way to (really) fix it.

An imperfect solution is always better than no solution!

 

[mcrawfordmusic]

I usually set mine between 35-40Hz, maybe higher on a particularly boomy stage. I use one mostly to clean up stage sound and then let the FOH guy deal with the room.

 

[agedhorse]

My opinion is:

- a HPF may make the bass sound subtly different (not worse! Different) even if the cutoff frequency is set lower than the actual bass content. Our ears are kinda sensitive to phase in the bass region. Bear in mind that peaks will generally get higher with a HPF as well if set below the frequency region where most of the energy is, so a HPF actually might demand some additional headroom. My mixing experience tells me that applying an (additional) HPF set even at 20Hz on bass will make the bass sound... sometimes better, sometimes worse. Sometimes it makes it punchier, sometimes it brings it too "forward".

Actually, ears are very insensitive to absolute phase at low frequencies. Peaks will not get higher with a HPF unless the Q is unreasonably high (approaching an oscillator), and will always improve the headroom. A HPF set to 20Hz with a critically damped Q will result in virtually no different in tone since it's at least 1 octave above the cutoff frequency of 99% of bass guitar cabinets. It may help a little but not much.

- if you do not slap, use percussive techniques, etc. there is little reason to use a HPF for protection, provided the bass cabinet is an actual bass cabinet. For example, I would always use a HPF if I were to play a Bass VI-like instrument into a guitar amp.

This is not at all true. Take a speakers rated at 400 watts RMS mechanically and drive it with an amp rated at 400 watts or more RMS and the HPF will improve the speaker's mechanical power handling at the lower frequencies. It will also reduce the distortion that's generated by driving a speaker below it's -6dB rolloff point (where distortion increases exponentially as the frequency falls).

- remember that mathematical overexcursion (Xmax) is not mechanical overexcursion (Xvar). Approaching and exceeding Xmax merely causes distortion (which may be inconsequential, or even pleasing in moderate amounts). When people say that they don't like high powered cabinets at low volumes, part of the reason is that the speaker is no longer distorting appreciably.

As the speaker reaches Xmax, the lifespan begins to fall as the suspension components are being driven beyond their linear limits. The farther beyond Xmax, the shorter the lifespan, this is not the kind of distortion most players prefer either. There is plenty of well known math behind the lifespan curves, that's what knowledgeable manufacturers base their ratings and warranty periods on.

A HPF is a tool to be used if necessary. My personal suggestion would be to start low and increase the cutoff frequency until it feels like you're missing something, then lower it a notch. Also, depending on the filter's resonance (Q), a HPF may actually make things worse for overexcursion because it is effectively boosting stuff around the cutoff frequency (high-Q filters essentially work as if there were a peaking filter around the cutoff frequency). Moreover, ported cabinets actually have more excursion problems in the second octave (around 80Hz) than around their tuning frequency, which is bound to be in the mid-40s up to the mid-50s.

A high Q HPF is not typical because it introduces tonal changes that may not be desired. MOST of the (successful) commercially available HPF's are in fact pretty close to critically damped (Q of .7). there are exceptions where the filter is achieving two things simultaneously, but that's not what we are discussing.

 

[Boneless]

Actually, ears are very insensitive to absolute phase at low frequencies. Peaks will not get higher with a HPF unless the Q is unreasonably high (approaching an oscillator), and will always improve the headroom. A HPF set to 20Hz with a critically damped Q will result in virtually no different in tone since it's at least 1 octave above the cutoff frequency of 99% of bass guitar cabinets. It may help a little but not much.

This is demonstrably untrue. Take any audio file, normalise it to near clipping, then apply a simple HPF at 20Hz, even critically damped. Unless there is significant energy at infrasonic frequencies and between 20 and 40Hz, the audio file will now clip. There is a reason why in mixing and mastering audio filtering tends to be done at the beginning of the chain, and anyway the last step is always the limiter. Also, we are insensitive to absolute phase everywhere *but* low frequencies (and we are never *very* sensitive anyway). AFAIK, people can pick a high passed bass (or kick drum) in a blind test quite reliably, even when it's far below the lowest frequency they generate.

This is not at all true. Take a speakers rated at 400 watts RMS mechanically and drive it with an amp rated at 400 watts or more RMS and the HPF will improve the speaker's mechanical power handling at the lower frequencies. It will also reduce the distortion that's generated by driving a speaker below it's -6dB rolloff point (where distortion increases exponentially as the frequency falls).

Of course, it can't hurt. I myself apply a HPF on all my wedge monitors or 2-way PA speakers, since they are not really expected to produce bass. Still, pro speakers (which bass guitar speakers essentially are) should be able to take some abuse though. And also, the truth is, most bass amplifiers already include some high-passing anyway. Not to talk about bass effects.

As the speaker reaches Xmax, the lifespan begins to fall as the suspension components are being driven beyond their linear limits. The farther beyond Xmax, the shorter the lifespan, this is not the kind of distortion most players prefer either. There is plenty of well known math behind the lifespan curves, that's what knowledgeable manufacturers base their ratings and warranty periods on.

I'm not talking about grossly exceeding Xmax, or even constantly pushing the speaker around Xmax. If it's just on transients though the speakers *should* handle it gracefully (proved by the fact that so many old cabs are still working fine; HPFs on bass is a relatively new trend), with some compression that many musicians actually find pleasing (otherwise, again, there wouldn't be such a thing as "that cab need to be pushed to sing"). Of course, if a cab is grossly underdimensioned, it sounds choked because it will be distorting lots all the time.

A high Q HPF is not typical because it introduces tonal changes that may not be desired. MOST of the (successful) commercially available HPF's are in fact pretty close to critically damped (Q of .7). there are exceptions where the filter is achieving two things simultaneously, but that's not what we are discussing.

I was never discussing high Q HPFs in general, that was just a side remark (although many HPFs used in mixing and mastering are relatively high Q, with maybe a 2-4dB peak around the cutoff frequency).