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strange electronic feedback

Posted: 7 Apr 2013 9:55 am
by Daniel Showalter
I have a Peavey Session %00 I am using onstage and I am getting a stgrange anomaly. It startedabout a year ago wheree it would feeback at a given frequency and checking last nite seemed to be an Ab (was an A position note but we tune down a 1/2 step for the singer). I eventually thought I cured it as it would only appear if I ran my signal from steel to tuner (Strobotuner) into effects (Boss digital Delay and an overdrive) to volume pedal to amp and I disonnected the tuner when I was performing but last nite just like the scary movies it was BAAACK.. It is not there if I go straght from just guitar to vlo ped to amp (but that doesnt mean it may not occur down the road. I initially thought it was an oscillatio (inaudible) in the tuner that was exciting something in the amp and still think that has something to do with it. What I don't know is if there is something wrong in the amp making it susceptable to this occurring. I also am thinking mabe it is related to the wall wart power supplies I am using but also wonder if the main poswer supply in the club has anything to do with it though it has happened in a number of venues. I am getting ready for a roed trip with thde band and can't have this. I am going to try to get my LTD working (needs a speaker and I have the replacement) but long term I want to get this resolved. Any thoughts?

Posted: 8 Apr 2013 6:58 am
by Stephen Cowell
I had to pull the midrange chip from my NV1000 to stop a similar problem... related to a defective (broken) mid-shift pot.

Your best bet is Peavey service... These kinds of problems are tech-killers and have caused many folks to stop servicing solid-state amps. Ship the chassis to them and let them take care of it.

Posted: 8 Apr 2013 9:10 am
by Dave Grafe
SO...you are saying that if you have your tuner OR effects unit inline you get the noise but if you bypass them the noise stops? Or are you saying something else?

You have not mentioned what effect you are using on your inline effects unit. If you are running a short delay with repeats - between 5 and 50 milliseconds or so - you can get a feedback artifact that reproduces a single note. That being said, several tuners do contribute to distortion when left connected, even if not inline.

Bottom line is if the noise does not happen when you are plugged directly into the amp - or via VP - your problem is not with the amp, look elsewhere.

Posted: 8 Apr 2013 3:16 pm
by Craig Schwartz
Dan you`ve got 2 of the sharpest cats chimin in , Dave and Stephen are top shelf, Theyve helped me out severely,
As a rookie, I just recently had a feedback issue and was stumped, I later added a noise gate into my effects and it cleaned up a huge volume hum that grew when I stepped on it, I didnt have to buy one because it was built into my modeling Pod , and all I had to do was switch it on,

Just a thought and by no means do I know what I am doing :idea:

Posted: 8 Apr 2013 5:39 pm
by Robert Daniels
I have a similar problem in my Session 400 Limited. I traced it to my reverb tank - does it go away if you turn down the reverb? I don't play the amp much (it's my spare).

reverbtank

Posted: 9 Apr 2013 12:34 pm
by Daniel Showalter
presently it is set up at home and like the proverbial car in the auto shop there is no problem so I cannot test it but it is beginning to appear to be A a problem that originates with a power supply issue either bad house power or something that affects the effects units and triggers a response in B) the reverb circuit. The sound bigins low and grows i intensity but with no string movement and volume at a level where true feeback is not an issue, it appears that the reverb circuit is magnifying the 'trigger" which is related to the effects/groundloop/bad power. My next experiment when it strikes again is to check the reverb turning it off to see if it goes away but that will only identify where in the amp it is not the cause so the other thing will be to try using battery power to determine if it is a power issue. If batteries eliminate the sound then I need to upgrade the wall warts or isolate them with graound lift. In the meantime I can do nothing more than to prepare and have batteries on hand and 3to 2 prong adaptors available for when it strikes again

Posted: 9 Apr 2013 1:42 pm
by Jon Light
I understand that this post is pretty irrelevant to the info provided in your posts but just to share:
Years ago in a Session 400 Limited I was having some real howling feedback and I discovered that the reverb tank had come loose, bag and all, and was magnetically affixed to the magnet of the Black Widow.
That ain't right.