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Noisy AT40-40

Discussion in 'Recording' started by Keith Christie, Jan 31, 2004.

  1. I have a pair of AT40-40 mics that I used on a live recording of a choir and heard a large amount of hi end noise. I went into the room and heard the pipe organ billows making noise. I later tried using them at home for a vocal overdub and had that noise again, I was going through pre-amps that I made so I thought it was the pre-amp, I switched to the console pre-amps (Soundcraft) and the noise was still there. I changed mics to a Sony C-48 and the noise was gone in both pre-amps. No body I know has heard of these mics being noisy. Did I just get a pair of "bad" mics or are they not as quiet as the specs indicate. Anybody out there with the same mics and problems?
  2. ozraves

    ozraves Active Member

    I wouldn't suspect you'd get a pair with the same exact problem. It's probably just the way your hear the world versus how guys who love the mic are hearing it. I found it to be a very quiet mic. It does have a certain frequency bump. If you got something putting out noise at that particular frequency or if your ears are plugged in to that frequency then it could be problematic (as it might be with any mic with a bit of a bump). My experience has been that the AT4040 is one of the best mics in its price segment.

  3. Thomas W. Bethel

    Thomas W. Bethel Well-Known Member

    AT is usually very good about talking to you about any problems. All the AT microphones that I own are very quiet and I use them for recording classical music so they have to be VERY VERY QUIET.

    Suggest giving the tech support people at AT a call and ask them about any problems. They will know about any reported problems and if needed can suggest some appropriate action like returning them for check out. They are located in Stow, Ohio.
  4. missilanious

    missilanious Guest

    well since they are a pair I would say your problem maybe lies on how you treat and store these mics, maybe you have some dirty diaphrams, the mesh screen on an AT4040 is very porous so dirt and sediment can get in there easily, and considering you do alot of acoustic recordings with them you most likely don't use a pop filter or wind screen. I own a AT 4040 and worked with a AT 4033, 4047, 3035, and 4050 and none gave me that problem.
  5. Thanks for the input. I have only used these mics a few times and I store them in their cases and inside an foam lined Anvil briefcase. So they are pristine. And because of the noise, "hiss", I haven't used them since. I don't think I'm just hearing it either, I wouldn't consider myself having "golden ears" to much Rock 'N Roll in my earlier years. I plan on calling the company and see what they have to say. I didn't think they would be that noisy even if they are in the lower price bracket for a studio condenser.
    Thanks again,
  6. Thomas W. Bethel

    Thomas W. Bethel Well-Known Member

    Here is an interesting question...are you sure your phantom is up to voltage (48 vdc measured at the microphone jack pin 1 to 2 and pin 1 to 3 with pin 1 being the common. If it is not your could be running the microphones on anything from + 1 volt DC to 48 vdc or on 1/2 wave AC. Also some microphones like to see different input impedences. These microphones want to see a "bringing input" somewhere around 3.2 K ohms and not a direct match. You did not say what preamps you are using so it is hard to know what their input impedence is.

    Can you check you phantom voltage and report back? Thanks.
  7. Tom,
    You may be on to something, the one pre-amp I built using a schematic out of an EQ magazine. It uses Burr Brown FET-input dual op amp and a instrumentation amplifier and they run on 24 volts. So that pre-amp only supplies 24 volts for phantom. The other pre-amp is out of a Soundcraft board that uses electronically balanced inputs at 1.8K ohm input inpedance. It has 48 volt phantom and meters at 48.8 volts. So that one should be fine except for the input inpedance. I don't know how that effects mics. I'll have to take it to work and try it with our Yamaha DM2000, that board should be set up to handle any studio type mic. Any other ideas or test I can try?
    Thanks for your help.
  8. Alécio Costa - Brazil

    Alécio Costa - Brazil Well-Known Member

    I´ve got 3 At4050´s and 1 At4040. Yes, it happened here in Brazil with a few folks. I had one repaired by At-US.

    a)Didn´t you connect the xlr cable with the phanton already powered on?

    b)with the At4050, lots of people reported this problem because they were changing patterens in the middle of recording sessions.

    c)Some people believe that is nice to change microphones after 3 hours of continuous use.

    d)always wait a few seconds before disconnecting your AT from the xlr cable. There is a time constant.
    hope it helps
    Yes, At rules

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