HPF before or after compressor

[BLDavis]

I've been running my Broughton HPF in front of my Diamond comp for a while now but, after reading through this thread, I was intrigued to try reversing the order. In my practice space I honestly can't tell any difference. I'll give it a try on a couple of live gigs this weekend and see how it goes
B.

 

[SteveBassJr]

Hpf before my comp. Thats how I roll!

 

[40Hz]

Always at the beginning of the chain. That’s my clean, unadulterated signal; so that’s what I’m going to feed everything else in line. Why would I make my effects process a bunch of uber-low end signal, then dump all of it at the very end anyway?

Depends on the use case. It’s hard to generalize too broadly since each signal chain is going to be different. So IMO it’s better to take more of a systems rather than cookbook approach.

Only problem with always putting the HPF up front is if you have any effects (e.g. an Ictineo, octaver, some dirt boxes, etc.) that put unwanted über-lows back into the signal chain downstream.

In my case, since I’m almost always running a passive 4-string bass, and my basses are more mid forward when it comes to voicing, a HPF at the front of the queue wouldn’t bring much to the party for me.

Where I might put an HPF before a compressor is if I were using a colorizing compressor (like a Smoothie or similar) towards the front, and a transparent compressor (like a Bassist) at the end of the chain to keep everything polite. So I could see putting an HPF in front of the transparent compressor - but still mostly at the end of the chain. (And I have.) Those two devices acting as a team go a long way towards quietly sweeping up any junk just before it hits the amp.

 

[BurningSkies]

The question is though: where are the excess lows, that need to be cut off, coming from?

If the effects add subharmonics, that's one answer. Aside from that, even if they boost the whole low end including subharmonics, they're just boosting what was introduced earlier in the chain.

This is why I use my HPF at the end of the chain. With some pedals (Xerograph, Future Impact, a few octave-down's) you're generating really low content.

...also, since I'm using the Cali 76CB there's no need to worry about the lows triggering compression prematurely, since it has side-chain HPF abilities.

 

[minddrain]

I experimented with oscilloscope software. Compressor first limits the wave. Cuts off highs and lows. As it should. So, reducing the dynamic range before the compressor would make it even tighter. However, fuzz and distortion (at least with the Source Audio Aftershock) add a ton of low end. So, after reducing the dynamic range you just add all bottom and no top back.

HPF after effects, well, reduce the bottom end. I suppose that’s why some people run two.

 

[Johno Dunn]

My signal chain goes, Zoom MS60b>Broughton HP/LP Filter>Broughton Silver Deluxe Pre>Eden GlowPlug>LS2 (Effect loop is Fairfield Accountant>Source Audio Manta)>Diamond Bass JR.>Yamaha DSR112 Powered Monitor. I run a very slight amount of commpression on the Zoom, the Fairfield is more for dirt and pop (a pseudo pick type tone), and the Diamond controls all the peaks, and adds it's magic. If you consider the GlowPlug to be a commpressor of sorts, you could say I have four compressors on my board, all doing different things. The HP/LP is after one, but before three! I've tried all configurations, and this works best for me. The HP/LP is invaluable! I'll never be without it. It is a life saver in all the tricky rooms we play, and a must for IEM situations at Church gigs.

 

[Zoot H Rollo]

I just got my Keeley Bassist

Good gawd, what a gorgeous comp. Quiet.

I get the Broughton HPFLPF next week

Planning the Broughton before the comp after the Peterson tuner

The Brought has gain, so ir will be interesting to balance with the Keeley

 

[micguy]

All my gigs are ampless. Given that, I'm not trying to protect my bass amp cabs (since I don't have any). The PA's that ultimately my signal goes through are more than capable of passing 30 Hz - no protection needed. I do have a high pass filter on my pedalboard, but it's only there to remove infrasonic stuff - it's set at 17.5 Hz. If there is a compressor in my signal chain (sometimes happens, but not too often) it's done at FOH. That's after my high pass.

If you're going to remove low frequencies from your signal, it's best to not have a compressor reacting to them, thus pumping what you are going to send. So, even if you're running a bass amp (and thus needing to remove some fundamentals to protect your speakers), I'd put the high pass before the compressor - in addition to protecting speakers, a high pass is there to remove signals that could mess up things like compression - if you put it first, the high pass does that - if not, then you're missing some of what it does for you.

 

[LetItGrowTone]

The variable side-chain HPF of the Empress Bass Compressor works perfectly. I'm satisfied that no HPF need come before it.

Some compressors - for example the Effectrode LA-1A and the Broughton Omnicomp - say they have an "A (or K) weighted" filter in the side-chain related to the ear's sensitivity to different frequencies. I would try to listen to this very carefully to see if it works better than an ordinary HPF placed before; it's possible, as some of these compressors are clones either fully or partly of circuits from long ago, and those guys back in the olden days really knew their stuff.

 

[frankzap]

Adding a high-pass filter before the compressor, set around 30-40Hz, can help clean up low-end spikes that might trigger the compressor, although this is not the main reason such a filter would be introduced. It's a practical move in general, especially since very low frequencies aren't always essential in most mixes. If you let the compressor work without low-filtering, it could overreact to those spikes and possibly affect the rest of the sound more than you'd like - that’s a new problem. The compressor's side chain filter (if available) would address this new one, but there's still a risk that some low spikes could slip through, causing issues down the line. Deciding whether to place the filter before or after the compressor depends on what works best for your setup.

Personally, I tend to skip the high-pass filter altogether. It's just not something I find absolutely necessary. If I were to use one, I'd place it before the compressor and set it at a low enough frequency (20-30-40 Hz) to not interfere with the musical style I'm working with and let the other effects process as much of the signal as possible. Just to eliminate accidental spikes that can create booming problems. From this perspective, a HPF can also be placed at the end of the chain, to remove accidental subsonic spikes, while processing the signal in any way up to that point. I am speaking for myself here anyway, not suggesting that this is the way to go. Others might find use cases that actually require using these filters. For instance, to cut some lows from a darker instrument, in which case it could be set at a higher frequency, and that would also justify placing it in front of the compressor, to eliminate the triggering problem. I tend to avoid introducing too much electronics though, especially filters, because they also twist signal phase and that can create other issues afterwards.

 

[amper]

My compressor comes right after my acoustic resonance enhancer. I use multiband compression exclusively, so I don't worry much about needing an HPF before the compressor. And it turns out I like the acoustic resonance enhancer before the comp better than the other way around. HPF, when I use it, goes at the very end of the chain, to catch any additional problematic lows that might get introduced by other effects after the comp.

I use my compressor to tighten up the sound of my instrument. I use it really as more of an expander than as a compressor, increasing my dynamics rather than reducing them, by using a relatively slow attack time to allow the initial attack of the note through before clamping down on the body of the note, and I compress the bass band harder, which tightens that up, with the overall effect being a snappier, sharper tone than I can get out of my instrument with fingers alone, since this also shifts the EQ balance of the instrument by compressing the treble band more lightly. No amount of practice on the instrument can do what a mulitband compressor can do.

I use the HPF to correct for dysfunctional venue acoustics.

 

[Zoot H Rollo]

 

[Zbysek]

This is one of the best presentations of usefulness of HPF I have ever seen...

 

[Zoot H Rollo]

Another good one from Pensado

 

[jj4001]

I put it last because I want the full frequency range of my bass interacting with my pedals. What I don’t want is the lowest frequencies making my vintage amps and speakers run hotter and work harder than they need to.

 

[PhatBottomBass1]

I'm using a pre-comp set @ 28Hz and one post-comp at the end set @ 48Hz before the amp/DI. My comp is not a vice grip and is very smooth. It just creates a nice presence and girth while staying really transparent with zero noise and no artifacts.

The first HPF just cleans up and takes out the real unusable frequency range and the second tightens the processed signal.

 

[gillento]

HPF at the beginning of the chain.
LPF, then comp at the end.

 

[mouthmw]

I'd put it last in the chain.
I don't use a compressor anymore, but here's my logic:
If you use an HPF with a frequency knob and you're setting it depending on the room acoustics, then it also affects how your compressor will react - so if you change your HPF settings, you'll probably have to tune your compressor for those changes too. That's not an issue if your HPF has the same settings all the time, but it is if you're tuning it for a specific room. Everything else that's sensitive to dynamics after your HPF will probably react different too - dirt, envelope filters, etc. So now it's knob fiddling time for those pedals as well. My reasoning tells me to use HPF at the end to cut off the unwanted low end and not to have it interact with dynamics sensitive pedals.