Why does everything have to add noise??

Discussion in 'The Stomp Box' started by ukepicker, Feb 13, 2020.

  1. edvard

    edvard Tele-Afflicted

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    Here you go. Nice and simple, low parts count, no batteries/power needed, -16dB dip right around 257Hz. The pot controls the depth. Put it all in a cleaned-up tuna can with a peanut-butter jar lid for the bottom. Or one of those small aluminum boxes if you want to go all fancy.
     

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  2. tele_savales

    tele_savales Tele-Holic

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    At the beginning of what?
     
  3. ukepicker

    ukepicker Tele-Afflicted Silver Supporter

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    Sweet! Thanks!
    I think I can make that happen, but I'm not sure I understand the properties of what each component is doing.
    If I wanted to make the 16dB variable, could I replace one of the resistors with a pot?
     
  4. ukepicker

    ukepicker Tele-Afflicted Silver Supporter

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    My cables are fine, my pedals are fine. I think most people wouldn't really even notice the noise.

    I think the thing that gets me is that I can turn the gain all the way up on my distortion box with almost no noise added (where I would expect to hear a little hiss). But on the EQ pedal - which is supposed to be a transparent tone-shaper - turning it on introduces noticeable hiss.

    I would like to think that any circuit will add noise. But when my distortion box doesn't add much and my EQ does, something feels off.

    I've had other pedals that weren't so bad - like the El Cap I used to have. Very little noise with that thing. JHS buffer (also supposed to be transparent) - unusably noisy.

    I test these things with just the pedal in the chain, on a true bypass looper. I can tell how much noise (hiss) is in the signal path with and without.

    I haven't tried batteries yet - I will when I get a few minutes of quiet (single-dad with a fiance is a very busy and often noisy life).

    Thanks to everyone for the kind posts.
     
  5. mexicanyella

    mexicanyella Tele-Afflicted

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    I was quietly enjoying a bowl of cereal at the breakfast counter. My wife entered the room. Noise added. I know what you mean.
     
  6. Bob Arbogast

    Bob Arbogast Tele-Afflicted Silver Supporter

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    I have one of those v. 5 pedals, and it's a good one!
     
  7. Switchy

    Switchy Tele-Afflicted

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    The process of learning how to setup my equipment properly.
     
  8. edvard

    edvard Tele-Afflicted

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    You mean sweepable? No. That one goes from flat to -16dB in only one spot. The circuit itself is a variety of 'Bridged-T Filter' that is arranged so we can have the top resistor replaced with a potentiometer that lets you swing from the input (flat) to the other side of the filter (notched). I simply plugged in values to LTSpice until the notch landed around where you were looking.

    if you want a sweep but no adjustable depth, you can do the other species of Bridged-T, but replace the resistor chain in the middle with dual pots wired like so:
    pot.jpg
    This will get you a -15dB notch anywhere from 100Hz to 1000Hz. If the sweep goes the wrong way, just wire it opposite from how it's shown here. I don't have a dual pot to confirm.

    If you want both depth and sweep, you'll have to go active, which also means notch AND boost. A couple of dual op-amps and a few parts will do you. See the EQ article at Geofex; he has a circuit AND the math:
    http://www.geofex.com/Article_Folders/EQs/paramet.htm
    Go down about halfway, there's an example circuit and the accompanying text gives you the math to arrive at the frequency you want. Hang only one Gyrator (the part in the dotted circle) and center it on 250Hz. You might even try notching out the hiss you are experiencing with a second Gyrator leg; with just the right Q, you could (in theory, anyway), seeking and destroy the hiss but leave the high end. Hopefully the low parts count also means it won't contribute much to the noise problem you already have.
     
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  9. LKB3rd

    LKB3rd Friend of Leo's

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    If you could solo the guitar on nearly any rock guitar song, you'd hear noise too. Electric guitars are hissy noisey raucous things.
     
  10. dickey

    dickey Friend of Leo's

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    For the same reason that everything that tastes good is bad for you,the side effects of most meds are weight GAIN istead of loss, and why chicks who are animals in bed are usually nuts in the head.
     
  11. ukepicker

    ukepicker Tele-Afflicted Silver Supporter

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    I like the center freq of 257hz. I think that will be just right. If it doesn't work, like I want, I'll look for other values. The paraEQ and my RTA should help me really pinpoint what I'm looking for. (But if my FOH experience has taught me anything, I think 257hz will be just right.)
    I'd like to make it variable from 0dB to -16dB (or something like that). By "top resistor" I think you mean R1, right? So if I made that a 50k potentiometer, it would let me vary the depth of the notch? Maybe even use a "no load" pot to bring it truly out of circuit?
     
  12. soundchaser59

    soundchaser59 Tele-Afflicted

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    I think it would be cool if I could hear up to 250k. I could probably find a way to monetize that ability.
     
  13. soundchaser59

    soundchaser59 Tele-Afflicted

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    Which planet is that on?
     
  14. Si G X

    Si G X Tele-Afflicted

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    Planet vintage Electro Harmonix
     
  15. Si G X

    Si G X Tele-Afflicted

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    ..... or Planet Jordan Bosstone.

    My Boss effects are the quietest pedals I own, what planet or you on?

    Digital Strymon Planet?
     
  16. 11 Gauge

    11 Gauge Doctor of Teleocity

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    In its stock form, the Jordan Bosstone is one of the noisiest effects of all time. The attack control in that thing is about as noisy as it gets.
     
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  17. edvard

    edvard Tele-Afflicted

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    Yes, R1 is a 50k potentiometer, and that's exactly what the circuit does; the potentiometer makes the notch variable from flat to -10dB (I know, I said -16dB, but at 1am, math is not my strong suit).
    Here's how it works:
    Potentiometer lugs are numbered 1 to 3 from left to right when looking at them face-on standing up, right? Let's say you want the response to be flat when the knob is fully counter-clockwise, and notched when the knob is turned all the way clockwise (swap lugs 1 and 3 if you want it to work the other way 'round). Then J1 should be hooked up to lug #1, C3 should be hooked up to lug #2, and C2 is hooked up to lug #3. When fully counter-clockwise, or "Flat", then the wiper is fully shorted to the input (J1) and you don't hear the filter. When fully clockwise, the wiper is shorted to lug #3, which is the other side of the filter, and we hear the full effect of it.

    Caveats: I drew this as simple as possible at 1am, so that means I forgot to mention; you'll want some sort of buffer between your guitar and the input. That may mean an actual buffer (op-amp or FET follower), or just a not-so-noisy non-true-bypass pedal just before it; I wouldn't just plug the guitar straight into J1. The low-impedance output of a buffer will make sure C1 and R2 won't load down the signal with an immediate low-pass response, and the high input impedance of your amp or another pedal at J2 will do the same for the output. If you'd like, I can draw up a more expanded version that "wraps" this in an active circuit, but then you've got basically another pedal at that point.

    Also, I don't think a 'no-load' pot would work in this scenario. Those are made with a gap in the carbon track right at lug #3, which will convert the circuit to a not-very-good low-pass filter.
     
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  18. The-Kid

    The-Kid Tele-Holic

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    Noise Gate?
     
  19. The-Kid

    The-Kid Tele-Holic

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  20. ukepicker

    ukepicker Tele-Afflicted Silver Supporter

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    That sounds great!
    I had already thought of the input impedance but I don't know much about that stuff really - thank you for taking the time talk me through it.

    Last night, I was thinking of how to include this in my signal path and I had decided it probably needed to be in a box with a buffer. I'm glad to know where to put it. Thanks!
     
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