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Best HPF (High Pass Filter) on the market?
- Thread starter Bassist30
- Start date
Why would you want 2 filter curves. I am talking about HPF past 35 hz. I can see it more with vocals and snares, etc. But why bass?
Because it's good to have steeper slope under certain frequency...
There are phenomenon at play here. The first is that the human ear can only hear frequencies down to around 20hz, at least in ideal listening environments. In complete silence (which is really hard to produce actually) In practice I've found that the ability to distinguish different pitches in a band context might be higher.
The second phenomenon are subharmonic frequencies, that can be felt but not heard, which often has the effect of muddying up a live sound mix but it also strains either your amp, your speaker, or both. It takes more energy to reproduce a frequency the lower it is. So your amp might be reproducing these frequencies that you can't hear, which effectively makes it less efficient. The more important part though ime is that the speaker and cab don't struggle as hard. There are many stories on TB of cabs with speakers that were farting out and hitting their max. After applying a hpf to remove subharmonic frequencies the farting stopped, which allowed the speakers to focus on the smaller window of low frequencies that it was being fed, therefore becoming louder and more focused. Which in turn, actually made notes felt, so the 'feeling' aspect of subharmonic frequencies aren't really lost, especially when those low frequencies are being hit by a kick drum anyway (which is why many live sound engineers high pass the bass at even 100Hz, to let drums fill the space along with minimizing a muddy room that's just low frequency rumble and mush).
Having -24dB means more of those subharmonic frequencies are cut while preserving the subharmonic frequencies. Essentially the 'corner' gets sharper the higher the number and moved closer to the cutoff frequency. So -6dB at 50Hz will actually be cutting frequencies at 80Hz or 100Hz lets say while not doing much lower than 50Hz. A -48dB slope at 50Hz means 50Hz and lower is essentially eliminated from the signal and since it's a sharp corner, maybe frequencies start getting cut at around 60Hz and only by -3dB.
Do you need a -48dB slope? Not really, there are some applications but there are some effects on tone that some have called "nonmusical".
There are people who are much more technically, musically, and experientially seasoned than I am though, so I'd want to double check anything I wrote
Last edited:
Passinwind
I know nothing.
- Dec 3, 2003
- 23,093
- 46,079
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- Designer/Toaster Tech @ Passinwind Electronics
It gives a different transient response feel than a classic texbook alignment, IME and IMO. Part of the reason for that is that there's nearly always some low end rolloff baked into the rest of the signal chain, and the composite response of the whole system is what's most important.
I'm not in US, I have an HPF in my pedalboard.
I can see 2 reasons why large scale pedal makers didn't include them in their catalogue: there's no a huge users demand and it's almost impossible to work with their marketing teams. Also, it's a clear benefit for an amp head/cab, so they're who are introducing these filters on the market normally.
I'm not in the US as well, and have an HPF. I have looked at the Broughton Audio stuff, but it is too expensive when you live across the pond (for my country: add a third of the price of the pedal with shipping for import duties etc.)
What is easily obtainable in EU:
If you are handy with a solder iron, or you know someone who is there are two kits from Schalltechnik 04:
The Mini HP Vong (similar to the Broughton Audio always on)
https://schalltechnik04.de/en/instructions/mini-hp-vong
The Vong Filterung (Similar to the Broughton HPF/LPF flter, but with an added DI)
VONG-Filterung – Schalltechnik_04
And if you want a built one;
there is Rafferty Guitars in Ireland, who have their own clone of the fDeck:
Rafferty HPF Pre 2 Bass Preamp / Adjustable High Pass Filter / Phase Switch Custom Color | Rafferty Guitar Pedals | Reverb
Or sfxsound in UK:
[sfx]:micro-thumpinator
[Invalid or Expired Link Removed]
Azure Skies
Commercial User
My European customers have frequently reported they do not pay duties. I guess the value is low enough that it's not always worth their time to charge for it.
Hi @Azure Skies! When I decided to get an HPF, yours was the first option but the shipment costs and the possibility to pay duties (I paid sometimes when goods coming from overseas) drove me back and got an european option. I don't know how big could be your european sales, but have you ever considered an importer?
I do have the Vong-Filterung
I've been fooling around with HPF alignments as part of my preamp design process and I've found that a straight 24dB/octave adjustable frequency filter is difficult to implement in practice (4 gang pots aren't super common) *and* I found it to be non-musical sounding at anything above 30 or 40Hz. A 12dB/Octave filter is more musical but doesn't provide enough attenuation of super low frequencies for ideal driver protection. 12dB/Octave what you see on most mixing desks. After much experimentation, I found that the best performing approach to HPF is a fixed 12dB/Octave at around 30Hz with a variable 12dB/Octave one cascaded after it. So rolloff is always 24dB/Octave below 30Hz and closer to 12 above. I'm not alone in that assessment so I can't be too out to lunch. It just plain sounds better to my ears.
To people looking at adding a HPF or HPF/LPF pedal, how important is gain? Is unity gain (in the non-filtered part of the signal) fine or do people want gain in this type of pedal?
For me, unity gain is preferred.
The only thing I don't like about the f'Deck III is that it is easy to mess up the gain structure as the little volume knob is easy to bump. Well, I actually don't like the form factor either but understood that its' original design was for upright and Francis modified it for us heathen electric players. I've considered by passing the volume control but don't want to take the chance of screwing up such a good thing.
The only thing I don't like about the f'Deck III is that it is easy to mess up the gain structure as the little volume knob is easy to bump. Well, I actually don't like the form factor either but understood that its' original design was for upright and Francis modified it for us heathen electric players. I've considered by passing the volume control but don't want to take the chance of screwing up such a good thing.
I don't need the gain knob on my HPF pedal...as I am using it as always-on type of effect.
I might feel differently if I wanted to switch it on and off during the show...
This is my general feeling on it, that it's typically used as an always on effect. Some of them offer up to 20dB of gain and I don't think that's necessary. The circuit I'm using naturally adds +4dB of gain (to get the q/response of the variable HPF to where I want it), so I figure if I put it in a standalone filter pedal I will either add a knob to go from -∞ to +4dB or just attenuate the +4dB to 0 internally and not use a gain control at all.
U
"The third option is quite nice to avoid the a drop in volume if the LPF is set to very low frequencies. That way it is possible to get reggae-like sounds without any volume drops."
VONG-Filterung – Schalltechnik_04
But, as you mentioned, could be cool to have a -∞ to +... kind of gain knob when you can't reach the amp knob.
Unity gain works for me. I think that the boost is intended when using strongly the LPF:
"The third option is quite nice to avoid the a drop in volume if the LPF is set to very low frequencies. That way it is possible to get reggae-like sounds without any volume drops."
VONG-Filterung – Schalltechnik_04
But, as you mentioned, could be cool to have a -∞ to +... kind of gain knob when you can't reach the amp knob.
I use the game knob on my series 3 as basically an on-off switch. It's nice to have it if it's close by. I do like the gain feature on my LPF hpf Broughton, but that's because I use it as a standalone preamp quite often
Does the input and output impedence matter much on a HPF pedal?
For example I found a European maker of HPF pedal which has a variable output impedence of 0-220kohm (with knob to adjust) and 1.8mohm input impedence.
The Broughton has for example other values.
Does it affect use and sound?
For example I found a European maker of HPF pedal which has a variable output impedence of 0-220kohm (with knob to adjust) and 1.8mohm input impedence.
The Broughton has for example other values.
Does it affect use and sound?
