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funkydoug

High Pass Filters

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Posted (edited)

More and more amp manufacturers are including a hpf in their products. Keep this in mind when you're on the market for a new amp.
The Ashdown ABM, Mesa class D amps and some others. Thumpinator is a nice tool for the job but an MXR 10 band EQ does the same and more. It's lowest bands are at 31.25 and 62.5Hz, you get the other 8 bands as a free bonus so you can sculpt your tone however you want.

 

Edited by DiMarco
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19 minutes ago, DiMarco said:

 Thumpinator is a nice tool for the job but an MXR 10 band EQ does the same and more. It's lowest bands are at 31.25 and 62.5Hz, you get the other 8 bands as a free bonus so you can sculpt your tone however you want.

Nope. An EQ pedal doesn't work in the same way as an hpf.

The MXR won't cut as effectively in the sub sonic (20Hz and less) space as the Thumpinator, so you won't remove low end "crud" as effectively. 

The MXR does, however, give you a lot more tone shaping options than the Thumpinator, no question.

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17 minutes ago, Al Krow said:

Nope. An EQ pedal doesn't work in the same way as an hpf.

The MXR won't cut as effectively in the sub sonic (20Hz and less) space as the Thumpinator, so you won't remove low end "crud" as effectively. 

 

Yep, it's not even the same ballpark at all.

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It does a great job removing unwanted on-stage boom though. I do not care how it does on paper.

 

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49 minutes ago, DiMarco said:

It does a great job removing unwanted on-stage boom though. I do not care how it does on paper.

Yup simply cutting bass frequencies can get rid of boom. But the MXR is a notch filter for all but the top frequency with a shelf filter at 16k, so apart from the 16k slider you're getting a peak cut at the centre frequency which diminishes either side.

A dedicated hpf will be cutting all frequencies below its cut off threshold by an increasing amount typically at -12dB/octave or -24dB/octave; it's having a quite different effect on your signal waveform. So it's simply incorrect to say that it "does the same".

As a 5 string player, I absolutely don't want a steep cut at both 31.25Hz & 62.5 Hz - that's the fundamental and first harmonic of my B string but I do want to get rid of low end crud. The Thumpinator starts cutting at -24dB/octave at 28 Hz and does what I want perfectly, the MXR won't be able to replicate, a steep cut at 31.25Hz and 62.5Hz will just leave my low notes sounding bare.

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Posted (edited)
1 hour ago, DiMarco said:

It does a great job removing unwanted on-stage boom though. I do not care how it does on paper.

 

 

If it works for you, great. But not all graphic EQs have a shelving type at the lowest band, and when they do they don't have a sharp slope like an HPF does. They do some of the job, but not as well. An adjustable HPF is even better still. If you could do the same with a graphic EQ nobody would waste their money with HPF units ;)

They're close like delays and reverb units are. A delay can be used as a kind of reverb, but very limited.

Edited by mcnach

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I'll order a Thumpinator and do a comparison then. 😁

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Posted (edited)
11 hours ago, DiMarco said:

I'll order a Thumpinator and do a comparison then. 😁

 

Best get an adjustable one.

The Thumpinator is good but it's designed more as a speaker protector, removing frequencies that won't get reproduced well by the speakers, and sounding pretty transparent. An adjustable one allows you to do the same, and more. By turning up the threshold frequency you can empirically find the best setting to remove excessive boom as well. Also, there's something really cool that happens when you combine turning up an HPF's frequency while simultaneously turning up the bass EQ. It sounds counterintuitive, but experiment with it, it allows you to dial in a fat low end that retains definition very well. I 'discovered' that interaction by chance and was a real eye opener.

Edited by mcnach
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Another Option, if you only need the HPF is the Mini VONG. Adjustable HPF between 30Hz and 140Hz. That's it...

They are available as a Kit for self soldering @ schalltechnik 04

Schalltechnik 04

..and there are also a few Guys @ Bassic, that do the soldering and sell them ready, put together and tested. Here is one HP and LP Filter brand new each for 40 Eur. (I am not the Seller, bought a ready one too)

Mini Vong @ Bassic

 

This little Unit is amazing if you only need an adjustable HPF

 

mini-hp-vong_30.jpg

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Never mind the mini vong. The full sized one looks great!

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7 minutes ago, owen said:

Never mind the mini vong. The full sized one looks great!

Of Course. I've had the full sized Vong, but only had used the HPF, so the Mini does exactly what i need plus i have won some space on my Board 🙂

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25 minutes ago, owen said:

Never mind the mini vong. The full sized one looks great!

Yeah. Looks very cool, and I love the 80's graphics! I'd put the filter controls in the opposite orientation, so that the curves would move as they'd appear on a graph- but I don't trust my soldering enough to build one! I'll have a look for a pre-made version, looks right up my street.

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Anyone able to recall / know what the steepness of the cut on the Vong is? 

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-12db/Oct fixed at 30hz plus -12db/Oct variable.

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I put a Stompshield over the Mini-Vong pot. Now the pot stays in place. I had to change the jack spacers outside the case to get enough of thread.

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Posted (edited)
13 hours ago, Jus Lukin said:

-12db/Oct fixed at 30hz plus -12db/Oct variable.

I seem to recall that the Thumpinator is 24db/octave @ 30Hz.

So would you need two of these to equate to the Thumpinator? 

So Mini Vong x2 = Thumpinator. 

Asking for a friend 😎

Edited by JohnDaBass
Context error

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3 minutes ago, JohnDaBass said:

I seem to recall that the Thumpinator is 24db/octave @ 30Hz.

So would you need two of these to equate to the Thumpinator? 

So Vong x2 = Thumpinator. 

Asking for a friend 😎

-12db/Oct fixed at 30hz plus -12db/Oct variable.

-12 + -12 = -24

I could be wrong.

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2 minutes ago, owen said:

-12db/Oct fixed at 30hz plus -12db/Oct variable.

-12 + -12 = -24

I could be wrong.

I think you are right and I believe the thumpinator is lower than 30Hz although I have never measured one and they do not publish a spec. 

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Yeah, filter curves are additive (even when subtracting!😄) so the Vong would be -24db/Oct below 30hz, similar to a Thumpinator, with an additional variable -12db/Oct above that for tuning to a cab or tone shaping.

I've floated the idea of something like this pedal with a couple of custom builders and after much bemusement and explanation came away with some pretty prohibitive prices. In fact the difference seems so much that I'm off to start a thread about getting a couple of these built!

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Just realised the VB-99 has a high and low pass filter under one of the advanced EQ settings. HPF lowest setting is 55hz. Works well with synths to stop uncontrollable rumble through the bass board. 

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52 minutes ago, ped said:

uncontrollable rumble

I live for that. 

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4 hours ago, Jus Lukin said:

Yeah, filter curves are additive (even when subtracting!😄) so the Vong would be -24db/Oct below 30hz, similar to a Thumpinator, with an additional variable -12db/Oct above that for tuning to a cab or tone shaping.

I've floated the idea of something like this pedal with a couple of custom builders and after much bemusement and explanation came away with some pretty prohibitive prices. In fact the difference seems so much that I'm off to start a thread about getting a couple of these built!

They sound great to me: variable f control and half the price of a Thumpinator, whilst matching the below 30hz "crud control" of the Thumpinator. What's not to like?! 

I sadly share your lack of soldering skills and had similar experience with price quotes for custom builds for similar spec. 

The only hesitation on getting one is thinking that my Helix should be able to match. 

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Sounds a bit like fdeck's HPF-Pre series 3 (fixed 12 dB/octave + variable 12 dB/octave)

The Irish builder Rafferty builds the fdeck series 2 (12 dB/octave). I don't know someone this side of Atlantic who builds a series 3.

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