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Truly Adjustable HPF?

Discussion in 'Effects [BG]' started by Reuptake, Aug 9, 2018.


  1. Reuptake

    Reuptake

    Aug 1, 2018
    The importance of an HPF could not be overstated, and I've read folks here getting into specifics about the frequency and slope of an HPF for the sake of tightening the sound of the band and preserving the life of our precious drivers. For product recommendations, all I've seen so far is fdeck's and Broughton's pedals, which have adjustable freq but a fixed slope. The same is true of my Grace m103, which has a HPF at 75Hz, and shelfing option for the bass eq freq. The slope for the shelving option is also not variable, and takes away the option of boosting a bass freq.

    Is there a pedal or single unit rackmount that will do what any generic DAW parametric eq will do: Select the frequency and slope of an HPF/LPF?

    If it costs $1000+, it would need to serve as a general purpose bass preamp/DI (or mic preamp, like my beloved Grace). Over $2000 and I'll just replace my speakers from time to time, and wade through the mud that permeates the air in my rehearsal space;)
     
  2. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Intergalactic Mind Space CA
    Song Surgeon slow downer software- full 4 hour demo
  3. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    So far I've only dabbled in DSP. My take is that it would be a big hurdle for me to develop a satisfactory DSP board that really works, and that solves problems such as dynamic range and power consumption. I've wondered if there's a tipping point, where my designs get complex enough to be simpler and cheaper if implemented in DSP, but I haven't found that point yet. So I continue to focus on what I'm capable of at the present time.

    Meanwhile, there's some really exciting things going on in open-source DSP technology. Here are some examples:

    The OWL

    Alchemist Pre-order

    Imagine taking a completely generic DSP with appropriate analog front/back end circuitry for musical instrument use, and provide a port for programming it to your heart's desire, or downloading programs that others have written. I think that's the future of effects, but it doesn't offer me a place at the table. So I'm happy to continue being a dinosaur for now.
     
  4. Reuptake

    Reuptake

    Aug 1, 2018
    I am not a fan of DSP except for when I'm sitting down to mix. Perhaps I may convert at some point, but I don't belive the tech is quite there yet for live work, at least for the sounds I try to get.

    I'm really curious what the technical hurdle is. I understand that electronics design is complex stuff, but I see some complex stuff out there. How is the slope of a cutoff attained, and is it possible to have a three-way switch that lets the user select 12/24/48db /octave? Is the problem that there aren't enough buyers out there to justify adding that feature?

    I looked a little closer at your series 3, and noticed the "12 + 12" curve, which may actually solve my problem (for significantly less than $1000!). 24db/oct is usually what I've found works best while mixing to tame useless freqs while keeping the bass as powerful as possible, although it would be nice to be able to keep that slope while dialing the frequency. As I understand it: there's always a 12db/oct slope at <35Hz, and an additional 12db/oct at <the freq it's set at, resulting in 24db/oct <35 and 12db/oct between 35Hz and the selected freq.

    The order form on your site shows up blank, likely due to a security issue, per your suggestion on the site. How might I go about ordering?
     
    HolmeBass, basscapes and Rock Salad like this.
  5. Ben B

    Ben B Supporting Member

    Jul 13, 2006
    San Diego, CA
    For PA, I love having DSP so I can adjust HPF and LPF frequency and slope. I also use narrow band parametric EQ for notch filtering. Very, very useful for PA. For bass, I think that's overkill which is probably why many acoustic instrument pre-amps have the HPF frequency adjustment, but no slope adjustment . I've found that a HPF like the fdeck + normal EQ controls on an amp or preamp is all I need. OP, are you really hitting a problem that you are trying to solve, or is this a theoretical discussion? Nothing wrong with theoretical, of course.
     
  6. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Intergalactic Mind Space CA
    Song Surgeon slow downer software- full 4 hour demo
    Try: http://personalpages.tds.net/~fdeck/hpf-tech-llc/hpf_order.htm
     
    gregmon79 and Rock Salad like this.
  7. Grumry

    Grumry

    Jul 6, 2016
    Nashville
    Get a 32 band rack eq for like $200 and have the most versatile high pass/low pass/room tuning capabilities ever.
     
    FugaziBomb likes this.
  8. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Intergalactic Mind Space CA
    Song Surgeon slow downer software- full 4 hour demo
    Put an HPF in front it.

    Digital has potential. There is slow downer software that is 31 band, 30 boost, 60 db cut.
     
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Except that most rack mount graphic eq's do not have adjustable frequency HPFs and LPFs, and none that I know of that do have slopes greater than 12dB/octave.

    If you go back to the earlier Yamaha products like the GEQ1231, they have an adjustable HPF but no LPF. A couple of Behringer models have 12dB/octave HPF and LPF, as does a BBE model, but generally they are not all that common. Most pro level products by DBX, KT, Ashley, etc. do not have both HPF and LPF that are adjustable as this is (was) usually done within the speaker processing system.
     
  10. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    That is indeed my order form. It's linked from my main website, but in an archaic way, and it causes modern browsers with good security settings to complain. For now, I'd rather keep that form straightforward, than try to create something clever that's less secure for everybody.
     
    packhowitzer likes this.
  11. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    As I understand it, having too steep of a slope can create its own problems. I've used both the Fdeck and Broughton hand have been more than satisfied with both...very well thought-out designs. OTOH, the HP slope on my PA is 18 BW which was suggested by somebody far more clever than I..

    Riis
     
  12. Reuptake

    Reuptake

    Aug 1, 2018
    Really trying to solve this. I'm not opposed to DSP in a PA, just haven't heard a guitar or bass sound good with the usual DSP suspects (amp emulation, distortion, various effects, etc.). My main concern with the HPFs I've seen out there with the 12db/oct is rolling off the low end that I want to hear in order to control the nearby mud. My experience in mixing informs me that I like what a 24db/oct shelf sounds like. It's possible that the 12db/oct convention will work fine, but even if it does I will want to hear what it sounds like at 24. I've heard some specific advice out there, like "set your HPF to 60hz at 24db/oct", but haven't found a piece of gear that will do it.

    Theory does, however, intrigue me. I am a 2nd year electrical engineering student (meaning I don't know anything yet). I am curious if the reason for not seeing this feature is technical (in which case I'd like to know more), or simply a lack of demand.
     
  13. ficelles

    ficelles Supporting Member

    Feb 28, 2010
    Devon, England
    I’m guessing there is a parametric EQ out there somewhere that will do what you want, haven’t found it yet though...
     
    Gizmot likes this.
  14. Reuptake

    Reuptake

    Aug 1, 2018
    I have an almost unhealthy fixation with knobs, particularly those that allow me to adjust things. At times I will begrudgingly accept a toggle. Accepted, that given a knob that allows me to adjust slope, wearing a blindfold I will likely land on 12, but without that knob I will insist with my dying breath that I needed a different slope.
     
  15. Reuptake

    Reuptake

    Aug 1, 2018
    So many I've seen that are close. The Tech 21 Q\Strip is a good example. Useful parametric EQ, though lacking q-control, with HPF and LPF. Just missing a slope control (or switch). My original comment about being able to so easily find this as a DSP refers to how most of the DSPs that I use in mixing simply emulate some piece of gear that people can buy and touch and ruin relationships over. Perhaps the universe is saving me from myself.
     
  16. ficelles

    ficelles Supporting Member

    Feb 28, 2010
    Devon, England
    DSP EQ is generally much more controllable than analog EQ, partly because it can be but mostly because it's easier to implement complex EQ with a GUI.
     
  17. ficelles

    ficelles Supporting Member

    Feb 28, 2010
    Devon, England
    Check out the Sine Effects MegaPara2, that's pretty close...
     
    31HZ likes this.
  18. Reuptake

    Reuptake

    Aug 1, 2018
    Ok, I'll suspend my prejudices for a moment: What device do I purchase to place this DSP EQ in my signal chain when rehearsing with a band or playing live? The link that fdeck provided, showing OWL and Rebel Technologies, has a page containing 213 patches, none of which include an HPF.
     
  19. Wasnex

    Wasnex

    Dec 25, 2011
    After reading a magazine interview with Stanley Clarke in the late 70s, I saved up to buy an Orban 672A. Eight bands of parametric EQ. Although each band has controls for center frequency, bandwidth, and 12dB of cut/boost, I believe the Orban was considered semi-parametric because the bands do not sweep from 20Hz-20kHz. Instead there is significant overlap between the frequency range of each adjacent band. The unit also has 12dB/octave HPF and LPF sections that can be configured as a two way crossover, which is how I used mine. Long out off production but they pop up on the used market.

    26280d1162846017-orban-672a-para-graphic-eq-orban672.

    I learned a lot using this piece and still own one today...more out of nostalgia than anything else. I would recommend spending a bit more and buying a modern parametric with less features as the audio quality will likely be better. Easy enough to create you own custom LPF and HPF slopes with 4-5 bands of good parametric EQ. Even better, get a digital mixer or speaker processor with parametric EQ that graphically displays the resultant response curve created from your inputs.

    I currently have a couple of Klark Teknik DN9848Es hooked up with computer control. These have parametric EQ, delay, and different crossover/HPF/LPF slopes up to 48dB/octave. I have been playing around with a 4-way system and 48dB/octave Butterworth filters and I am really pleased with the results. I have tried retuning the system a couple of times to with 24dB L/R filters and have not been able to improve the sound. I have done all the tuning by ear, so perhaps the results would be different if I had a program like SMAART.
     
  20. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    Buy two 12db/oct HPF's and set them to the same frequency. If you like it, keep them, if you don't, sell one.
     

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