High Pass Filters

[Stub Mandrel]

36 minutes ago, Baloney Balderdash said:

Well, except for the 25Hz being the -3dB point of the slope, so there will most definite be a couple of dB reduction of 27.5Hz as well, and the low B for that matter at 30.87Hz slightly reduced too

 

Absolutely, and I didn't mean to suggest otherwise, but at 36dB per octave the cut at 27.5Hz will be minimal and at 30Hz, undetectable to the human ear.

 

This graph off talkbass shows 0.5bD cut at 30Hz, which is well below what the ear can detect.

 

Edited October 27, 2023 by Stub Mandrel

[Chienmortbb]

46 minutes ago, Baloney Balderdash said:

Well, except for the 25Hz being the -3dB point of the slope, so there will most definite be a couple of dB reduction of 27.5Hz as well, and the low B for that matter at 30.87Hz slightly reduced too.

 

I realize this is nit picking, and for most parts irrelevant as any real life cab actually used is unlikely to be able to reproduce 27.5Hz, or 30.87Hz for that matter, anyway (it will however, as we can see in that video, still cause the speaker cones to flap, just not producing much of an actually audible tone), and what is actually mostly heard will the the second harmonic, an octave above, and our brain filling in the blanks (as with a large part of our perception of reality in general really).

 

Just saying for the sake of being factual correct.

 

You are correct but it is worth pointing out that the amount of fundamental we hear is negligible. Some highly respected cabinets have -3dB points in the 60-70 hz region. I believe that the Thumpinator was originally designed to filter out the FoH low end. In my opinion it is too low for bass although it will help. 
 

if you have a variable HPF to hand, try a  cutoff of 50Hz at 24dB per octave. You will be surprised how much “bass” is there, whether playing a Low E or Low B. As for a destined 6 string, don’t be silly. 

[Lfalex v1.1]

1 hour ago, Chienmortbb said:

 

If you have a variable HPF to hand...

 

I wish! 

All I can see in the marketplace ina pedal format is Broughton's offering,  and that's mighty expensive. 

[Chienmortbb]

13 minutes ago, Lfalex v1.1 said:

 

I wish! 

All I can see in the marketplace ina pedal format is Broughton's offering,  and that's mighty expensive. 

 

There are HPFs out there. Sadly, many only for the DIYer. I know my friend @Passinwind is planning a variable HPF.  You can also get it on some multi effects units.

[Baloney Balderdash]

2 hours ago, Chienmortbb said:

You are correct but it is worth pointing out that the amount of fundamental we hear is negligible. Some highly respected cabinets have -3dB points in the 60-70 hz region. I believe that the Thumpinator was originally designed to filter out the FoH low end. In my opinion it is too low for bass although it will help. 
 

if you have a variable HPF to hand, try a  cutoff of 50Hz at 24dB per octave. You will be surprised how much “bass” is there, whether playing a Low E or Low B. As for a destined 6 string, don’t be silly. 

But?

 

It's more or less exactly what I said.

 

You quote it yourself:

3 hours ago, Baloney Balderdash said:

I realize this is nit picking, and for most parts irrelevant as any real life cab actually used is unlikely to be able to reproduce 27.5Hz, or 30.87Hz for that matter, anyway (it will however, as we can see in that video, still cause the speaker cones to flap, just not producing much of an actually audible tone), and what is actually mostly heard will the the second harmonic, an octave above, and our brain filling in the blanks (as with a large part of our perception of reality in general really).

 

Personally though I prefer cabinets with better low end frequency response than you mention, something closer to -3dB at 45Hz and with a HPF set at 40Hz, but you are right a lot of bass cabs have a frequency response similar to what you mention.

 

Also try take a look at the linked video, and behold just how much the 25Hz HPF helps a regular bass cab:

15 hours ago, JPJ said:

If anybody is interested there’s a great video showing speaker cone extension without, and then with a Microthumpinator HPF. This visually demonstrates the “subtle effect”

 

SFXSound Microthumpinator

 

 

 

Edited October 27, 2023 by Baloney Balderdash

[Downunderwonder]

5 hours ago, Lfalex v1.1 said:

 

I wish! 

All I can see in the marketplace ina pedal format is Broughton's offering,  and that's mighty expensive. 

Back up the thread there's someone selling sharply priced units on ebay. Build to order for the most part iirc.

[Downunderwonder]

There is also Vong kit if you are handy with a soldering iron.

[SuperSeagull]

On 25/10/2023 at 18:59, peteb said:

I'm thinking of adding a HPF to my set-up to free up some headroom on my amp and control a bit of the boom you occasionally get in some venues. I assume that a LPF would help with that? If I get one, should I put it before or after the compressor. 

 

I'm afraid that  haven't waded through all 19 pages of this thread, but has anybody used a Sine Effect H24 HPF pedal and is it any good? Or would I be better looking for a micro-thumpinator second hand? 

 

I’ve recently added a Sine HPF. It’s replacing a Rafferty which I really like but it’s just a bit big for my board. So far, in two rehearsals, the Sine seems to be doing exactly the same as the Rafferty so I’m happy. 

[Downunderwonder]

3 hours ago, SuperSeagull said:

Sine

That's the one. 

[pete.young]

On 27/10/2023 at 12:16, Lfalex v1.1 said:

I

 

 

So it feels like the Thumpinator almost ought to go at the beginning of the signal chain; to clean up all the infrasonic gubbins before it reaches your FX and amp.

 

 

 

This is what Max from SFX recommended when I asked him where to put mine.

[Al Krow]

You could almost make the case for having two! One at the start to present a crud-free signal to the pedals and one to clean up any low end crud created by the pedals. 

 

Overkill? 

 

Edited October 29, 2023 by Al Krow

[peteb]

3 hours ago, Al Krow said:

Overkill? 

 

 

Yep... 

 

[peteb]

I should say that generally I like the sound of my rig, but at SOME venues I've found that I need to turn the master volume higher than I would really like and occasionally you get a booming bottom end where I have had to cut loads of bass on the amp, which again I would rather not have to do. The idea is just to cut some of the unnecessary low frequencies to free up some headroom in the amp and to send a signal to FOH that makes it as easy as possible for the sound engineer to get a good bass sound as quickly as possible.  

 

I am going to use a HPF pedal on a gig next week that @LukeFRC has very kindly offered to loan me to get an idea how it will work, but I am tending towards a micro-thumpinator at the front of the signal chain at the moment. 

 

[PaulWarning]

whenever I've had booming it's not the very low end but around the 100Hz range, I thought, maybe mistakenly, that anything below about 30 Hz is inaudible to the human hearing, well it is to mine anyway

[peteb]

15 minutes ago, PaulWarning said:

whenever I've had booming it's not the very low end but around the 100Hz range, I thought, maybe mistakenly, that anything below about 30 Hz is inaudible to the human hearing, well it is to mine anyway

 

You might not be able to hear it, that isn't to say that it isn't there causing havoc with the low frequencies being sent to the desk. 

 

[PaulWarning]

On 29/01/2018 at 21:49, Mottlefeeder said:

I'm not sure that I agree with that - if your sound is boomy due to a hollow stage, and HPF can tame the boom, similarly if you want more punch and less mud, an HPF plus bass boost can fix that for you. In both cases you can hear the difference.

David

I wasn't saying a HPF is not worth having, I use one myself, the Zoom B1on has one, just referring to the above post

[BabyBlueSound]

I have nothing of value to add but please look at my beautiful green Rafferty

 

[Chienmortbb]

On 29/10/2023 at 18:20, PaulWarning said:

whenever I've had booming it's not the very low end but around the 100Hz range, I thought, maybe mistakenly, that anything below about 30 Hz is inaudible to the human hearing, well it is to mine anyway

You are correct but we must all try to think of an HPF as a necessary pre-shaping of the bottom end rather than an effect. The ultra low end of bass is not musical and an HPF cleans up the mud and stops excess power being sent through the amp to the speaker. This means that the speaker runs cooler* as does the amp if you are using a Class A/B amp. It also means that the drivers do not over extend. It is win win!

 

*As speakers warm up they gradually quieter due to a phenomenon called power compression. 

[Downunderwonder]

I think power compression is when the speaker does not respond linearly to more power. At that point it is turning the extra power into heat instead of sound at a greater rate than it does at lower volume. The extra heat makes things get tighter and then it gets quieter, sometimes to the point no sound comes out at all if the player ignores the warning and turns up some more instead of taking a break.

[Maude]

I have an F Deck HPF which I had made in a very simple format. It went pop at last night's rehearsal and released the magic genie. I've just opened it up to see if I can fix it and it really is an very easy build for a semi competent DIYer. 

I didn't have frills, just an in and out, a power in and a variable filter knob, I didn't want battery, on/off switch or anything else, just a simple always on filter that I could tune slightly. 

This is the insides. 

If anyone wants to build one I can take some clearer close ups. 

 

[Downunderwonder]

Smoked a capacitor. I wonder how that happened? No chance you poked it with 18V by accident?

[Downunderwonder]

Fdeck published his schematic for free use by DIYers btw.

[paul_5]

 

here’s John K’s version. I’ve built this layout and it’s great. The transistors were expensive (6 -7 quid each) but there are opamp layouts in the net too.

[Maude]

2 hours ago, Downunderwonder said:

Smoked a capacitor. I wonder how that happened? No chance you poked it with 18V by accident?

I started a thread in technical/repairs so I'll continue there instead of clogging up this thread. 👍

 

 

[stewblack]

Thread revival. 

20 pages way too much to plough through. 

Quick question: how, given the HPF removes inaudible frequencies, do you tell if it's working?