Why basses don't come with a HP filter in the electronics?

[Lorenzop]

Hi all

I'm a electronics noob but:

1) Why basses always lack a HP filter (say integrated with the tone knob, active or passive) - when instead a mix Engeneer reaches for a HP asap when mixing bass?

Ok in mix context is different BUT wouldn't a HP filter in tone control, maybe set at the lowest fundamental of bass (4 or 5 string) or indeed a sweepable HP make ALOT of sense, as first in signal chain thus removing crap out of bass before hitting pedals, preamps, compressors and power amps?


2) Second question, is a HP filter difficoult to build? As an inboard HP? Wouldn't it be possible to put in an active bass electronic? Or even passive for that matter?

A lot of good, even hi-end active bass preamps (Jreteo, Glockenklang, Eden etc etc) offer a lot of good tone filters but why none has a switch for HP filter???

 

[Lorenzop]

Thanks

 

[Camaro]

It does exist:
http://www.bestbassgear.com/acg-eq-02-preamp.htm
Haven't tried it yet.
But I'm also surprised its not a more popular concept.

 

[Emanuel Apascaritei]

Because it´s a bass!!

 

[Jay Corwin]

Run a search for fdeck HPF on the DB side here. You'll find all of the information you're looking for.

 

[jd_watt]

Interesting idea, one I've been considering too. I wonder if it would be beneficial to run a HPF, at 30 or 50hz before the signal hits certain pedals or FOH. Might be best to let the soundman handle that too though...

 

[capcom]

I think the real problem is lack of emphasize in 'low-mid' frequencies in most EQ designs.

The traditional 3-Band "Bass - Mid - Treble" type EQs are not very adequate to especially shape the 'low-mid' area which is in the region of around 125Hertz, lies between the sub bass and middle frequencies... Altough both newer preamps and head designs have some extra EQ controls to adjust low-mids. Therefore cutting "Bass" control and boosting Low-Mids behaves very much like a High Pass Filter.

The sweepable mids EQ concept also helps to mimic behavior of a HPF. For example traditional Ampeg sweepable mid knob at 1st position is centered at 220Hertz, you just cut the bass a little bit and boost the mids at 1st position gives you kind of very good, full, round, punchy bass sound without excessive low-end rumble very much like acting like a HPF.

But I am still with you that having or adding an extra HPF to an actual EQ be it onboard or on a head preamp would be very nice, afterall it's a very nice option to have.

By the way by adding an HPF to a traditional "Bass - Mid - Treble" type EQ also "saves" the whole unit by giving more tonal opportunities. There was a long thread about a very good HPF unit built by a member of this forum also.

 

[Bass4LifeRS]

It could potentially be used to get more power out of your amplifier too, since it wouldn't have to reproduce the ultra lows.

 

[nashvillebill]

With electric guitars, however, sometimes a different approach is used. The full signal from the guitar is used through the first or second gain stage of the amp, then comes the HPF (in a tube amp, just a low value coupling cap). The idea is that overtones from the low-frequency stuff can generate useful harmonics as the tube is overdriven and distorted. (I've tinkered with this but not enough to be an expert) Too much though and everything turns to mush.

 

[Passinwind]

2) Second question, is a HP filter difficult to build? As an inboard HP? Wouldn't it be possible to put in an active bass electronic? Or even passive for that matter?

Do a TB search on "FMOD" for an overview of the passive approach. Downsides: insertion loss and/or a fairly shallow rolloff slope. A 3rd or 4th order active filter typically uses at least two opamp or other active device stages, so board size and current consumption issues are possible design constraints.

With electric guitars, however, sometimes a different approach is used. The full signal from the guitar is used through the first or second gain stage of the amp, then comes the HPF (in a tube amp, just a low value coupling cap). The idea is that overtones from the low-frequency stuff can generate useful harmonics as the tube is overdriven and distorted. (I've tinkered with this but not enough to be an expert) Too much though and everything turns to mush.

There's some interesting ground to be covered with those concepts in bass amps too, IMHO. Maybe a little too interesting for me to want to share my own ideas about them...Link Removed

 

[David Jayne]

It does exist:
http://www.bestbassgear.com/acg-eq-02-preamp.htm
Haven't tried it yet.
But I'm also surprised its not a more popular concept.

That doesn't do what you think it does. I've got one. The lowest the Hi Pass filter will go is to about 1K. The unit has no provision for chopping lows from the bottom up.

 

[delta7fred]

The 3 band Musicman preamp does have a HPF built in, can't remember the cut off frequency but IIRC it is 12db/octave, admittedly it is not as steep as the Fdeck but better than nothing.

 

[Passinwind]

The 3 band Musicman preamp does have a HPF built in, can't remember the cut off frequency but IIRC it is 12db/octave, admittedly it is not as steep as the Fdeck but better than nothing.

Yep, my quick and dirty sim shows something like -3dB at 60Hz, 12dB/oct slope.

 

[Lorenzop]

Been looking around for FDeck but could find how to buy one???

 

[walterw]

The 3 band Musicman preamp does have a HPF built in, can't remember the cut off frequency but IIRC it is 12db/octave, admittedly it is not as steep as the Fdeck but better than nothing.

Yep, my quick and dirty sim shows something like -3dB at 60Hz, 12dB/oct slope.

wait, it has a rolloff at 60Hz? is that independent of the actual bass EQ knob? where does said knob boost typically?

 

[khutch]

My new passive Squier VI has a built in HPF. They call it a strangle switch but it is a HPF and when you engage it the tone control knob varies the cutoff frequency over a pretty wide range although it cuts of pretty much everything if you turn it down all the way. I am going to hazard a guess that the reason they are not more popular is that they aren't that useful in normal circumstances. Maybe they have a use in recording, I wouldn't know. I have played with mine quite a bit by now and the only useful setting I have found so far is "OFF". If you really want one they are easy enough to add and like I said if you follow the Bass VI strangle switch schematic you will get a variable HPF when the HPF is engaged.

 

[Passinwind]

wait, it has a rolloff at 60Hz? is that independent of the actual bass EQ knob? where does said knob boost typically?

Walter, my model isn't optimized for MM pickups at all, so I wouldn't put any great stock in it beyond that there is indeed a 2nd order HPF. That 60Hz figure (-3dB point, cut actually starts well above that) is with the bass control at noon, which appears to be the nominal flat position. Looks like the bass control boosts with a peak at 70Hz, taking interaction with the HPF into account, but cuts from an octave or so higher up. I haven't built one of these yet, but I definitely want to eventually.

In my new DIY amp build I used a scheme similar to the Fdeck3, but with the -3dB point varying from 25 to 95 Hz. The way it interacts with the bass control lets you set the bass peaking point over a very broad range, which seems very useful so far. Those who dislike interactive tone controls would probably hate it though!

 

[Geri O]

That doesn't do what you think it does. I've got one. The lowest the Hi Pass filter will go is to about 1K. The unit has no provision for chopping lows from the bottom up.

Then that, my friends, would be called a LPF, or a low pass filter.

 

[N.F.A.]

Pretty sure Alembic comes with hpf built in.

 

[Passinwind]

Then that, my friends, would be called a LPF, or a low pass filter.

Nope, it's called a frequency swept treble control. Take a look at that link. Link Removed