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getting stray frequencies recording

Discussion in 'Recording' started by Rider, Feb 18, 2005.

  1. Rider

    Rider Guest

    my recording setup is basically as follows:

    gibson SG supreme p-90s > line 6 spider 210 > box containing one of the line 6 speakers and a 20$ nady mic > imic (using a 250-50k ohm transformer) > my mac > logic express 7

    problem:

    i am getting very very harsh spikes of various frequencies, usually around 2.5khz

    details:

    i have ruled the recording input method out, as i plugged my headphones into the amp and can still hear the harsh sound. that knocks everything out past the spider 210. i can also slightly hear it in the speaker cone when i listen to it up close.

    i highly doubt it is my guitar as i am getting the spikes from other sources. guitar is not completely ruled out, but theres no reason for me to believe it is the guitar anymore.

    i also doubt it is the amp, but it looks the most likely. i had this problem also when i was going guitar > zoom 707 pedal > imic, so... what?

    i even unplugged everything in my apartment wondering if it had to do with something giving off a bad signal.


    i am so confused right now.

    sample of the guitar tracks with no logic effects on. the guitar sounds good, but there is a strange harshness that is also showing thorugh.
    http://nowayride.dyndns.org/music/example.mp3

    sample of me touching the end of the cable. the noise is generally what i get while recording.
    http://nowayride.dyndns.org/music/what.mp3

    i havent been working with recording stuff long, but this does not seem normal for a guitar to sound like going straight through. all the EQing in the world will not fix the sound, and of course sharp cuts into the sound just weaken the guitar a LOT.


    any advise? guesses? anything?



    forgot to mention... my amp is really messed up. again i doubt this would be the problem considering through the zoom i had the same problem but.. the amp's left channel is fried or something. i accidentally left the amp on one day when i went to school. i came back and it was humming. i plugged my guitar in and only the right side was working. right side has not worked since them. i just ignored the problem and went on my way. i plugged headphones in recently (when i tested the amp) and they FRIED one side. i snapped off the foam and it looked like someone started to burn it with a lighter. first off.. what the hell? second, how could an amp melt headphones, headphone jacks are not suppose to be that strong right?
     
  2. Treena Foster

    Treena Foster Active Member

    Sounds like a 60 cycle hum to me. Do you have any florescent lights near your plug in/out let, or over head where you sit/stand to play?

    :? Treena
     
  3. Rider

    Rider Guest

    that does sound like it could be interference. the deal is, i am in an apartment so i dont know what would be interfering exactly. my kitchen has an overhead light, but it is never on when i am recording. doesnt seem like it would interfere if it was off. not sure about downstairs whether or not her having it on would interfere too. it is not that close, my desk is about 10ft away from the kitchen.

    would 60 cycle hum interfere if i have a 100% isolated environment, like if guitar was in batt amp then into say tape player, or would the electronics pick it up from the wall anyway?

    whatever is happening, if al lelse fails, i can just use my computer for editing/dummy recordings, and record my tracks elsewhere like at my grandparents.

    im going to look into 60 cycle hum more, thanks.
     
  4. Treena Foster

    Treena Foster Active Member

    Yes, it can be coming from the wall jack if it's not grounded, (three way plug).

    :wink: Treena
     
  5. xaivious

    xaivious Guest

    I took a listen to your sample. It sounds like your problem is buzz, not 60 cycle hum. In sound engineering BUZZ and HUM are defining two very different things.

    HUM occurs at an actual 60 hz. This sounds more like a low rumble that oscillates a bit. This usually happens when two pieces of equipment are hooked up between each other while plugged into two different outlets with separate paths to ground (a ground loop). Lifting a ground will elliminate the loop.

    What I think I hear is BUZZ, which is a product of inductance. Though it is not a flawless diagnosis without being there. 60hz AC current is chopped up by some things. These things include Fluorescent light ballasts, power transformers, electric motors, and SCRs (silcon controlled rectifiers). If you are not familiar with what an SCR is, it is a common device used to attenuate current with anything from lighting dimmers to some electric heater adjustments. The harmonics of this chopped up 60hz (hence the buzzing sound) is then inducted into the signal. That is why it is heard at higher frequencies like 2.5 khz.

    Since we are talking inductance it can be tricky. It does not matter so much if you are plugged into the wall, because it is airborn.

    So what is causing your buzz, where is it coming from? It is always around us in most living situations. Only the ground usually drains it before it reaches the signal. Even a close power transformer on a pole outside (or those big green ground boxes) produce a significant amount of chopped up 60hz harmonics that can be inducted through a wall or many walls. But it would have to be pretty close. I would suggest first checking for SCR dimmers (they are common and often over looked). I was at a friends jam party a few months back. They had a terrible buzz, I took one quick look around saw track lighting. I said those have a dimmer don't they, yep. As soon as they were turned off it was gone. As Treena mentioned fluorescents (ballasts) are another source, neons are even worse. Realize if you are in an apartment it could plausibly be coming from a neighbor, but less likely.

    Be aware that if your amp has had shorts, it likely has some damaged shields. Shorts can screw up a lot of things, like frying headphones. No, headphone outs should not get that hot, but a short could mean that something is crossing the signal that should not be.

    Technically BUZZ has to be very strong to overpower a good shield. Meaning usually from a high voltage tranformer being within 50-100 ft, or something of normal voltage within 10ft or so. With a bad shield it will almost always be a problem, because it does not take much. Also, when tracking guitars be aware that guitar pickups are perfect for picking up BUZZ. Walk near a TV or computer monitor with and electric plugged in and you get an example.

    Note apartment complexes are often terrible for BUZZ problems since they are often swarming with SCRs and high voltage transformers. But I would suggest starting with the shorts in the amp, then check out lights and SCRs.

    If you are looking up more on the noise itself, reference BUZZ not HUM.
     
  6. Rider

    Rider Guest

    excellent post thanks SO much. 1-10 it gets 11 and a :cool:

    re: headphones, thankfully i logged in my repair status and it says they are replacing the cup for free! so happy!

    youre right im thinking of buzz i just did not know the actual term for it or what all causes it. hmm.. ive tried with all the lights out, with a ton of things unplugged, im really running out of sources here. i have switched amps to a less problematic amp (losing a lot of quality but its far more trusting). one of these days ill probably go DI or straight through an amp with a multieffects pedal.

    the only thing i can thikn of now is air conditioning either from me or a neighbor. im across the room from the neighboring wall (so >10ft away from them), far away from the other side of me, only thing is directly below me. only thing i know of that is below me is a TV (which would not be on at 3AM as she does not stay up that late).

    i guess i have to just keep looking around.

    out of curiosity, should a chip on a line 6 amp be too hot to touch? it seems like amp electronics hsould not be getting that hot, but maybe they are suppose to, i dont know anything about them.

    thanks again for your great advise!
     
  7. xaivious

    xaivious Guest

    Chips can certainly generate a lot of heat, especially if on for a while. What is too hot depends... It can be quite hot to the touch depending on the chip and design. Normally if it was too hot it would burn out fairly quick. I would just make sure it is getting proper ventilation.
     
  8. Dave62

    Dave62 Guest

    Try spreading the equipment out. I had a guitar player once who put an effect pedal on top of his Mesa Boogie amp. When he turned it all on there was a horrible buzz and when I asked he said it always did that. I removed the pedal from the top of the amp and the sound went away. He was shocked. The transformer in the amp puts out a huge magnetic field and the poorly shielded stomp box picked it all up.
     
  9. Rider

    Rider Guest

    guitar > logic > logic's guitar amp AU > CD

    still gets it, just not as bad.

    even EQed out the high end so its all 100-1khz rolling off before it gets to the offending frequencies.

    still whistles.. not as much.. but i can still hear it whistle.

    im really thinking theres something awful in the walls or something.
     
  10. karbomusic

    karbomusic Active Member

    Listening to example 2.... Do you mean the "screeching/whistling" sound every so often?

    First off lets discount the noise and hum for a moment as I think it is secondary.

    If what I hear is what I think it could be you may be hearing a component in the actual amp cirucuit feeding back. This can happen from time to time especially in combo amps turned up real loud with distortion. It could be as simple as the foil in a capacitor whose resonant frequency is the same as notes in your sound. This could by why it is only happening in spots where the frequecies match and the foil vibrates violently for a moment then stops as soon as the supporting frequency level drops.

    Since the offending sound is in the 2-5k range try cutting the treble or better yet the presence if available on the spider to see if it helps.

    I also thought the pickup could be feeding back but if so you would not hear it by touching the plug alone with the guitar unplugged.

    Back to the noise/hum... It is there but it and the 2k thing are probably two different components. Unless... the noise/hum is so loud that it actually contains the frequency that vibrates the amp and causes the "foil in the cap" to vibrate...

    Tests/Cures?

    Cut treble as mentioned above, turn down the amp or you could use an external speaker cab (the combo spkr is acoustically coupled with the amp via the cab), however, its a spider and unless you get a line6 speaker cab you will probably suffer colorations in the sound you like since it is a modelling amp and the speaker is sort of "neuteral" theory wise...

    If you have this problem at all volumes then none of the above may apply...

    Best regards-

    Karbo
     

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