1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Aguilar Agro Feedback / Whistle Problem

Discussion in 'Effects [BG]' started by maguire, Dec 14, 2012.

  1. maguire


    Nov 24, 2010
    NYC / Westchester
    I'm wondering if anyone has experience with an Agro pedal producing a high pitch constant feedback sound.

    Yesterday I ran an active stingray through a compressor and into the Agro. When I turned both the saturation and volume dials past 3/4 turn, the pedal made a high pitched feedback sound. I could eventually balance it out so 1/2 volume and 3/4 saturation did not create the whistling sound. But anything past 3/4 on both and it would whiiiiiiiine like crazy.

    This wast first time using the pedal. I bought it used. Anyone know if I have a bum pedal or maybe just overloaded it with signal?

    I thought it should be able to handle the input signal.

    Thanks in advance for any information/ experience!
  2. lipancek


    Jan 22, 2011
    My Agro does somethimg similar when I crank the saturation knob past 3/4. But it isn't a problem for me since I never use it with that saturation setting. I bought it new by the way.
  3. maguire


    Nov 24, 2010
    NYC / Westchester
    Thanks for the reply!

    That's a bit of a relief to hear. I'm hoping that its just a common result of over-dialing.

    I'm pretty green about pedals.
  4. willbassyeah


    Oct 9, 2011
    Yes it is common. Mine react that way too. Sold it after i get my b3k.
  5. maguire


    Nov 24, 2010
    NYC / Westchester
    Thanks will.

    I think this should be a helpful thread for people wondering about the Agro "whistle". Any other experiences with this Agro characteristic would be greatly appreciated.

    I am going to try it with a passive bass to see if I get a different result.

    I'll post the results.
  6. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion

    Aug 25, 2010
    The Great Midwest
    Same here I had the Agro sold it now have the Tone Hammer just as noisy I'm not sure if you can hear it in a live situation or not?.
  7. willbassyeah


    Oct 9, 2011
    hmm the problem is not the fact that the pedal is noisy, but it creates feedback when the pedal is on, i am not sure why though... One think i remember clearly, the pedal react differently at different times. i think it might got to do with me standing near the amplifier and cranking the saturation knob too much, <- example on how feedback is being made (mine literally create that type of feedback)
  8. Laurent

    Laurent Supporting Member

    May 21, 2008
    Napa, California
    I did not experience feedback situations with the Agro but noted the pedal did not work well with other pedals in the chain. By itself it was fine but with other pedals in front of it, weird tones were generated.
  9. maguire


    Nov 24, 2010
    NYC / Westchester
    I did NOT get the feedback with:

    Active BAss > Agro (only pedal in chain) > lower volume output on the amp.
    Passive Bass > Agro (only pedal in chain) > lower volume output on the amp.

    Ill try it at higher volumes next practice.
  10. willbassyeah


    Oct 9, 2011
    i use a fender passive -> sansamp bddi -> mxr bass comp-> agro when the pedal start to feedback, i remember it quite clearly, as i was trying to nail killing in the name tone with the agro, i am pretty sure i cranked the saturation knob quite high to nail the tone.
  11. Aguilar/Dave B.

    Aguilar/Dave B. Aguilar Amplification Commercial User

    Nov 8, 2003
    New York City
    President: Aguilar Amplification
    Hi Maguire,

    Here is a slightly technical explanation of what happens and why from our very own Goran Stankovic. I hope it is helpful and answers your concerns.

    Best, Dave B.

    Any time a signal is passed through a circuit that contains filters and/or inverters, the phase of the signal is altered.
    When a signal is passed through multiple circuits or a circuit with multiple filters, its phase can get altered to a point at which the output of a circuit can become in phase with the input, given that the feedback path between the two is provided. At this point the circuit will start oscillating – feed backing.

    Every electronic circuit that contains a gain stage is subject to this behavior.
    Exactly when the circuit will become unstable and start oscillating will depend on the amount of gain in the circuit, and the parameters related to the feedback between the output and the input of the circuit.
    If a particular system (made out of multiple effects) oscillates at one setting, reducing the total gain in the system will make it stable again.

    Quality and position of cables (routing on the pedal board for instance), shielding (or the lack of it) of the instrument and pickups, proximity of the instrument to the amplifier and/or cabinet are some of the factors that can increase the amount of feedback between output and input of the circuit, and make it more prone to oscillation.
    crguti likes this.
  12. Laurent

    Laurent Supporting Member

    May 21, 2008
    Napa, California
    I have a Tone Hammer as well and wanted to check on this.
    I did experiment with his and got the pedal to feed back.
    That being said to achieve this I had to put through an insane amount of gain (volume and gain almost all the way up). So I tried to reproduce the same thing with my Markbass F500 amp and sure enough given enough gain and volume I got there.

    My take away is that the Tone Hammer offers such a huge amount of gain and tonal correction that it is possible to make it feed back. Most boosts don't seem to offer as much gain and I suspect this is why I had not experience feed back before.

    It is also important to note that using the pedal in normal condition (without everything turned up and standing close to the amp) will NOT generate feedback.

    Likewise I don't think the pedal is noisy. It offers so much tone correction (I think it's 18db) that it amplifies everything. Silence amplified can become noisy!

    I continue to be impressed by the Tone Hammer and I think of it as one of the best DI ever built.