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Idea to help tune foldback quickly.

Discussion in 'Miscellaneous [BG]' started by Petebass, Aug 15, 2003.


  1. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    I've got another one of those gigs comming up where I have to do the PA as well as play bass. However it's looking more and more like I'm going to have very little time to set up, tune the foldback, then soundcheck.

    I've found I spend more time tuning the foldback than anything and had an idea which may speed things up. Trouble is I don't really know if it will work.

    I have a multimeter that can measure frequency in Hz. I was thinking that I could run a lead from the parallel output of the wedge to the multimeter. Turn the monitor volume up until I get a little bit of feedback, and hopefully the multimeter will tell me what frequency is feeding - or will it?
     
  2. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Bump.

    C'mon guys. The gig is in a few days and I'm in a bit of a bind.

    For what it's worth I tried it on my home stereo and it worked. But 100w Hi-Fi is a lot less that the 1,000w+ I'll be playing with at the gig.

    Anyone?
     
  3. Jaysound

    Jaysound

    Jan 9, 2003
    Australia
    You're right, I don't think your little multimeter would cope with 1000 watts! My suggestion would be to set up another mic, (or split the signal from the vocal mic.) It will pick up the feedback, and send a much lower level to the multimeter. You just need the right lead/adaptor, what's the input on the multimeter?
     
  4. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Ladies and gentlemen, allow me to introduce Australia's best sound engineer........ If Jay says so, then so it is!

    So I guess I should be looking to measure the signal elsewhere in the signal chain, preferably before the amplifier. If I understand you correctly, feedback by it's nature will be present in a loop everywhere in the signal path.

    I've had another idea. If I use my bass to find out what music note the feedback produces, I should be able to use the attached chart (and my ears) to figure out what frequency is feeding. For example, if it's feeding an "E" note, and it a high pitched feedback, it's gotta be either 10K or 5k ish. If it a low rumble feedback playing a "D" note, it's gotta be either 75Hz or 150HHz.

    Make sense?
     
  5. jondog

    jondog

    Mar 14, 2002
    NYC metro area
    My singer owns our PA. He has a Behringer :bag: eq that automatically locates feedback frequencies and filters them out. Other companies make these too, I think PV's is called a Feedback Ferret. They *really* work and greatly reduce our setup time. We tried turning it off for 1 set just to see what happened. Feedback happened, and usually we have none.
     
  6. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Actually the company I work for imports, among other things, Phonic PA gear. If you took away Behringer, Phonic would be among the cheaper brands out there, but the stuff is surprisingly decent (notice I didn't say brilliant).

    However, the feedback destroyer just won a back to back shootout in Europe against some stiff competition. On the strength of this, my boss has decided to bring them into Australia but they won't be available here for a while yet....... I love working here but it's trippled my GAS!!!!! Now I know why guys who work in music shops have 47 basses and a new amp every few months :)
     
  7. Jaysound

    Jaysound

    Jan 9, 2003
    Australia
    Yep, that would work too... you're just full of good ideas aren't you ;) Good luck with the gig.
     
  8. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    I've been let off the hook. The gig start time has been moved back an hour. I should have plenty of time now, though I still might use the chart......
     
  9. Why not download a frequency generator. I have one.. want it?

    Burn the frequencies to cd. Play it and knock out them that way. A guy did that here. He had this sweep on a tone generator. Took him 10 mins to knock out the band frequencies.

    *shrugs*

    :D:D

    Merls
     
  10. Jaysound

    Jaysound

    Jan 9, 2003
    Australia
    So even though you had extra time, did you try out the multimeter idea? You've got me curious now.....
     
  11. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Nah I used the frequency/note chart. It worked.

    But if you wanna borrow my multimeter and try it on your PA, you're welcome to it.