High Pass Filters

[Al Krow]

1 hour ago, Downunderwonder said:

And still the misconception lives.

 

Fundamental frequencies are seldom produced by the subs in professional application. The -10dB sensitivity point on the RCF might be 30hz. To make 30hz as loud as 80hz would take 10x the amount of power. So no point in trying, either the whole system has to be throttled back or the subs get given death by the low EQ being goosed.

 

I have given a club owner a proper fright with my highpassed system being sound checked with a keyboard powering up on 11. Oops. I don't remember if he didn't want the synth psychedelic metal band anywhere near his PA or the band knew mine was better for purpose but I got the call.

 

The club had more subs than me but maybe they hadn't been properly high passed.

 

Put the big energy into 60 to 90hz. WHOMP! Sure gave the guy a fright.

 

No disagreement from me, that all makes good sense. My point was more a "both/and" i.e. if you want a big low end sound then some decent subs are going to help - we would still have hpf on all channels on our desk apart from the kick drum.

[Lfalex v1.1]

Just had a try using my old Zoom B3 between an Ampeg pre-amp and the return of the FX loop on my Markbass Head.

The Ampeg gets the lot, then the Zoom affects what the power amp stage gets. 

 

There's a little compression, and I'm using the Facsimile of the Fishman Platnum pre as an HPF which is -12dB/octave @ 40Hz.

I tried running two HPFs to give -24dB/octave but it sounded over-processed. I've no idea what "order" the filter is. Maybe that's relevant. 

 

It's not working too badly at all. 

Especially for something that was laying unused. Might try it in front of the Ampeg, to see what that does...

 

 

 

[Chienmortbb]

38 minutes ago, Lfalex v1.1 said:

I've no idea what "order" the filter is.

An order is usually 6dB, so 12dB is second order, 18dB is third Order and 24dB is fourth order.

[Elfrasho]

I've always set my HPF at 50hz, and I sound great. 

[Mottlefeeder]

2 hours ago, Lfalex v1.1 said:

...I tried running two HPFs to give -24dB/octave but it sounded over-processed. I've no idea what "order" the filter is. Maybe that's relevant. 

 

 

 

I tried an experiment using the speaker box calculator WinISD - checking the responses of a 4-pole filter and 2 * 2-pole filters, all supposedly Butterworth. The 2 * 2-pole filter had a much gentler knee than the other, so that may have been part of what you heard.

David 

[SuperSeagull]

On 19/08/2023 at 19:16, jrixn1 said:

 

+1.  Many people go by a specific frequency or number on a dial - but yours is the correct way!

 

 

 

Francis Deck (designer of the Rafferty) puts it like this:
"Flip the phase switch. The feedback will get worse, or better. You want it to be better."

🙂

 

 

Ta re the first point. Good to know. I need to listen to the phase switch, I’m not sure I’ve really done that yet. 

[Stub Mandrel]

13 hours ago, Paul S said:

This is all very interesting.  I am a died in the wool technophobe - my brain is wired in other ways - so please forgive an elementary question. 

 

My band uses a Soundcraft Signature 22 desk and the channel I go through has a HPF button.  Would this do the same thing?  Ditto kick drum.

 

I understand that most sound engineers would use the Soundcraft 100Hz HPF on all channels except bass, kick drum and maybe keyboard. I was told that by a professional sound engineer about two weeks ago because I asked him specifically when I should use it.

[Chienmortbb]

52 minutes ago, Stub Mandrel said:

 

I understand that most sound engineers would use the Soundcraft 100Hz HPF on all channels except bass, kick drum and maybe keyboard. I was told that by a professional sound engineer about two weeks ago because I asked him specifically when I should use it.

Good advice although I would use it on the keyboards too. Solo keyboards might be OK without, but in a band setting you need to keep those pesky pianists out of our sonic space.  I always worry when they say,  I can do that on the keyboard. 
 

 

[Stub Mandrel]

7 minutes ago, Chienmortbb said:

Good advice although I would use it on the keyboards too. Solo keyboards might be OK without, but in a band setting you need to keep those pesky pianists out of our sonic space.  I always worry when they say,  I can do that on the keyboard. 
 

 

 

 

Played Superstition the other week and the keyboard generously let me do all the funkhy bits!

[Al Krow]

2 hours ago, Stub Mandrel said:

 

I understand that most sound engineers would use the Soundcraft 100Hz HPF on all channels except bass, kick drum and maybe keyboard. I was told that by a professional sound engineer about two weeks ago because I asked him specifically when I should use it.

 

Would you bother at all with hpf for your bass eg by using a separate hpf pedal if you're not making use of the hpf on the desk? If so, what frequency level do you kick it in and how steep a cut?  

 

Just as a fyi for any other Soundcraft Signature desk users, the hpf on these desks cuts at 18dB/oct from 100Hz - so it's decently steep.

 

Edited August 20, 2023 by Al Krow

[Chienmortbb]

Most desks I have used use 75Hz as the HPF although 100 would be fine by me for everything but the Kick and the bass.  However we need to look at why we are filtering. At the bass players rig, the requirement is different and depends on whether the bass goes through the FoH or a bass rig. Although the reasons are slightly different. At the rig the HPF both clears up the mush and protects the drivers from over exertion. 
Those going amp-less can leave the HPF to the FoH technician. 

 

[Al Krow]

33 minutes ago, Chienmortbb said:

Most desks I have used use 75Hz as the HPF although 100 would be fine by me for everything but the Kick and the bass.  However we need to look at why we are filtering. At the bass players rig, the requirement is different and depends on whether the bass goes through the FoH or a bass rig. Although the reasons are slightly different. At the rig the HPF both clears up the mush and protects the drivers from over exertion. 
Those going amp-less can leave the HPF to the FoH technician. 

 

Not every band going amp-less has the benefit of a FoH technician though, and if you are going amp-less as a bass player surely the reasons are pretty much the same as someone using a rig i.e. it clears up the mush and protects the PA drivers from over exertion?

 

Edited August 21, 2023 by Al Krow

[Stub Mandrel]

8 hours ago, Al Krow said:

 

Would you bother at all with hpf for your bass eg by using a separate hpf pedal if you're not making use of the hpf on the desk? If so, what frequency level do you kick it in and how steep a cut?  

 

Just as a fyi for any other Soundcraft Signature desk users, the hpf on these desks cuts at 18dB/oct from 100Hz - so it's decently steep.

 

 

My hpf is 24dB/octave -3dB at 30Hz.

 

I hear what people say about the value of getting the low harmonics, but I use a cab with a -3dB point at 35Hz and di into  a PA with subs that go down to 32. I sometimes play 5 string or drop D so having a setup that can handle it, why not use it?

 

To me the value of an hpf is losing handling noise and rumble not gaining headroom I don't need by losing the fundamental.

[Baloney Balderdash]

On 29/01/2018 at 20:00, BigRedX said:

You shouldn't be able to hear what a HPF is doing. The cut-off point should be set below the range of normal hearing and just filtering out those frequencies that are causing excessive cone movement but aren't actually producing any audible bass.

I disagree!

 

Applying a HPF at the right frequency, eventual boosting the right low frequency and then applying a HPF at the right frequency, can really tighten up the low end of your signal and make it punchier.

 

Edited August 28, 2023 by Baloney Balderdash

[Paul S]

On 20/08/2023 at 08:54, Al Krow said:

Hi Paul - in short, yes. We have a Soundcraft Signature 12MTK and the hpf kicks in at 100Hz.

We've got hpf engaged for all the channels, including bass, apart from the kick drum which has key frequencies in the 50Hz to 80Hz range and is not being hpf'd. 

I remembered to look at the last gig. It appears that the hpf has been engaged the whole time 🥴😁

 

[Al Krow]

5 minutes ago, Paul S said:

I remembered to look at the last gig. It appears that the hpf has been engaged the whole time 🥴😁

 

On absolutely everything, including the kick drum? 

[Paul S]

Just now, Al Krow said:

On absolutely everything, including the kick drum? 

No, just 2x vox and the bass. 

[Al Krow]

Ok cool - and if I remember correctly your guitarist is using backline rather than going through the PA.

 

We've similarly got everything other than the kick drum hpf'd. Seems to work well: the bass and kick are consequently not in competition for the 50Hz to 80Hz range which gives a really good unmuddy mix with the kick laying the foundation for the band.  

[Lfalex v1.1]

44 minutes ago, Baloney Balderdash said:

 

Applying a HPF at the right frequency, eventual boosting the right low frequency and then applying a HPF at the right frequency, can really tighten up the low end of your signal and make it punchier.

 

 

I think you should be able to hear some difference when an HPF is functioning correctly,  even if the bulk of its effect is below frequencies that a bassist would find useful. 

Even without adjusted LF EQ, the HPF ought to liberate some extra headroom from the amp it's connected to, simply because it's saving the amp/cab/combo (and PA) from wasting power trying reproduce frequencies that the system simply cannot generate. 

Quite apart from that, it should filter out said "useless" low frequency content, leaving the worthwhile low-end behind.

 

Whilst subtle,  there is an audible difference,  even at low levels. 

And I'm only running something that behaves like an HPF at -12dB/octave from 40Hz down. 

[Al Krow]

Was at a main stage at a festival gig tonight, listening to the support act to the headliners. Awful drowning rumble from the bass through FoH, I could see the poor fella fiddling about with his on board EQ controls and then stopping playing. Their sound engineer should be sacked - clearly not all of them have incorporated hpf into their workflow! 

[PaulWarning]

7 hours ago, Al Krow said:

Was at a main stage at a festival gig tonight, listening to the support act to the headliners. Awful drowning rumble from the bass through FoH, I could see the poor fella fiddling about with his on board EQ controls and then stopping playing. Their sound engineer should be sacked - clearly not all of them have incorporated hpf into their workflow! 

just come back from Stone Valley midlands, the sound was very variable, I can only assume that some the bands had their own sound engineers, The Undertones singer could hardly be heard, Ash wasn't much better, the Ska bands mostly had a decent bass sound but some of the others were booming, I can only guess that they had a trebly bass sound and the sound guys were trying to get some bottom end out of them.  The Skids had the best overall sound from the bands I heard,

I think Michael Bradley of the Undertones was using a Trace Elf, looked like it from where I was standing, I was wasn't overly impressed, sounded a bit flabby to me

[BigRedX]

Can you make a meaningful assessment of the bass amp capabilities when what you are hearing FoH is probably direct from the bass guitar?

[fretmeister]

57 minutes ago, BigRedX said:

Can you make a meaningful assessment of the bass amp capabilities when what you are hearing FoH is probably direct from the bass guitar?

 

 

Is it though? Most of the time I see the di taken from the amp. Even if that is pre-EQ it's still getting any baked in sound and whatever pedals are being used.

[ped]

Any advice on where to use an HPF, I currently have a chain which goes bass-pedals-comp-DI-output

 

Would it make sense to have it after the DI, before the comp or in between the comp and DI? Or right at the start?!

 

I know, it'll be best to experiment but is there a general consensus?

[Chienmortbb]

1 minute ago, ped said:

Any advice on where to use an HPF, I currently have a chain which goes bass-pedals-comp-DI-output

 

Would it make sense to have it after the DI, before the comp or in between the comp and DI? Or right at the start?!

 

I know, it'll be best to experiment but is there a general consensus?

In my opinion, I would put the HPF at the front of the chain but possibly after any DI. That will make it easier on the rest of your signal chain.