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High Pass Filters


funkydoug

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My question is ...  should I get one??? :facepalm:  I think I've been doing too much reading and have convinced myself that i need a HPF to protect speakers and improve efficiency etc. My amp doesn't have one and dedicated pedals seem a tad pricey for such an apparently simple thing. When I say pricey I mean they don't come up 2nd hand and are hard to justify when I am not sure if they are going to make an audible difference.

What 's your experience been and is it worth the cash and having to carry another box + power supply? 

About me: I play a passive but high output 4 string Jazz through an ABM Evo4 through some combination of a BFM Jack 12 and an Ashdown 408 neo cab. Rarely if ever plan to use both cabs together by the way .. but you never know!

Thanks folks :)

Edited by funkydoug
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IMO everyone should have one.  It's one of those things you don't realise you need until you have it.

I built my own (fdeck HPF-Pre clone from this layout) and was absolutely amazed how much amp power I had been wasting. I immediately had to turn my amp down around 25% as it was no longer trying to reproduce a load of inaudible sub-frequencies and therefore was working much more efficiently.

It seemed to make my bass sit in the band mix a lot better, and dramatically improved the string-to-string balance of my bass (prior to the HPF I suffered from a boomy E string and struggled to get the EQ to compensate well enough).  I suspect my speaker cabs are a lot happier as well.

As always, YMMV, but I'd highly recommend one.  They can seem "expensive" (obviously mine wasn't as I built it) but once you compare it to the cost of speaker recones/replacements etc caused by driving them with inaudible subsonics, I'd say they're worth every penny.

Edited by Johnny Wishbone
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I have a Thumpinator. I can't say I can tell any difference in tone apart from less cone movement but it makes me less afraid to crank my amp up!

You already mentioned the amp aspect but worth noting that plenty of amps such as Genz Benz already feature a fixed HPF so a separate one would be unnecessary.

If you typically push your amp/cab to its limits to get enough volume then you may find one beneficial. Plus it gives you an excuse to get a pedal board and find more pedals to connect to that power supply!

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+1 for the Thumpinator. 

Having read thread after thread from the legendary Dynamic Cab Duo Phil & Stevie I became more aware of the theory behind the effectiveness of HPF. At the time I was using Fender Rumble 500 head into one or two Basschat mk1 cabs. The HPF Thumpinator had a marked impact on the performance of my rig, tightening and cleaning up the bottom end without any loss of low end bass. If your amp does not have an HPF on board the I would recommend using /getting one.

Edited by JohnDaBass
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2 hours ago, 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'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

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11 hours ago, 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

There are HPFs and there are HPFs.

The OP is asking about devices like the Thumpinator which are designed to remove sub-audible frequencies from your signal path which are below normal human hearing and therefore don't contribute in any way to the sound of the bass. These devices all have a fixed cut-off frequency (around 30Hz) and slope of at least 24dB/oct. You can't hear them working because you can't hear the frequencies they are removing, but your amp will have been wasting power trying to reproduce them, and they are potentially damaging to your speakers. This has nothing to do with corrective EQ for taming excessive audible low frequency boom.

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5 minutes ago, BigRedX said:

There are HPFs and there are HPFs.

I'm also potentially in the market for one, so this thread is very timely for me. Grateful for recommendations for some good quality HPFs?

Any besides the Broughton, that combine HPF with LPF? That would seem to be ideal.

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8 minutes ago, PaulWarning said:

Trace Elliot GP12 does the job for me, or any parametric EQ should do it

Cheers - would a PEQ patch on something like a Zoom MS-60B or Zoom B3n multifx be up to the job, or should I be looking for a dedicated pedal?

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13 minutes ago, Al Krow said:

I'm also potentially in the market for one, so this thread is very timely for me. Grateful for recommendations for some good quality HPFs?

Any besides the Broughton, that combine HPF with LPF? That would seem to be ideal.

What do you want it to do? Remove sub-audio frequencies or tame the audible lower end of your sound?

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Not many para-EQ pedals have the flexibilty to offer LPF/HPF. Usually they are high/low shelving with notch/peak for the mids. According to the marketing at least, the Thumpinator has a more complex filter purposely designed to have as steep a roll off as possible without having a peak around the cutoff frequency or affecting the audible range.

There's not many out there Al, the FDeck and Thumpinator units were the original only two you could really get in pedal form, then you have Broughton and the Tech21 Q-Strip which you know about. Not aware of any others but I did hear the Zoom units could be set up as an HPF from one of the users around here.

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4 minutes ago, Al Krow said:

Primarily to remove sub-audio frequencies.

Probably the Thumpinator then. However as has also been said check that there isn't a device in your signal path already doing this first.

I'm not sure about the Broughton pedal, you'd need to try it, but for me looking at the spec 12dB/oct isn't steep enough to be as effective as the Thumpinator.

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For the DIYers among us, Julian Pohler (Mr. Shalltechnik04 - the guy behind the Guma Drive, Guma Antique and Growling Krizzly kits) is bringing out a combined HPF/LPF + DI kit soon called "Vong" (no idea what Vong means). I've asked him to keep me posted on when it's to be released.

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1 hour ago, Al Krow said:

Cheers - would a PEQ patch on something like a Zoom MS-60B or Zoom B3n multifx be up to the job, or should I be looking for a dedicated pedal?

I've got a Zoom B1on and that has a parmetric EQ with a 'Q' adjuster, that controls how many frequencies you're adjusting (google it I had too) very flexible

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On the Zoom bass pedals, the AC BS Pre is a clone of the Fishman Platinum Pro. The 'Depth' control is a HPF at 12dB/oct - not as steep as the Thumpinator but might achieve some of the desired effect.

Thanks Bigwan, great minds think alike :-)

 

Edited by pete.young
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16 minutes ago, pete.young said:

On the Zoom bass pedals, the AC BS Pre is a clone of the Fishman Platinum Pro. The 'Depth' control is a HPF at 12dB/oct - not as steep as the Thumpinator but might achieve some of the desired effect.

Thanks Bigwan, great minds think alike :-)

 

Indeed!

Chaining 2 of these together will have the same effect (in theory) as a 24dB/octave roll off. That's how these filters typically work, 2 identical 12 dB/oct filters in series.

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