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custom racking

Discussion in 'Pro Audio Equipment' started by Newatthis, Jan 24, 2004.

  1. Newatthis

    Newatthis Guest

    Hello, can anyone reccomend a place to rack a couple of Langevin AM16 mic preamps with maybe polarity switching, phanto & input/output controls? Other than Mercenary since they seem very high priced.
  2. Bill Park

    Bill Park Guest

    Most any music store or electronics shop can do it for you. The reason to go to a place like Mercenary is that they have done it before, and understand perhaps a little more about it than the typical music store. But if you are looking for the cheapest job short of doing it yourself, take it to your local music store or A/V contractor.

  3. Newatthis

    Newatthis Guest

    Bill, it's not that I'm looking for the cheapest way but a thousand dollars seems high for my 1st quote. I'm just trying to find some other good people/service to compare it to. Is there anyone with some history of this type of experience that could be recommended. Thanks.
  4. Bill Park

    Bill Park Guest

    I was serious when I suggested your local music shop or A/V house. Nothing wrong with looking there.

  5. Newatthis

    Newatthis Guest

    Thanks, Bill. I never really gave much thought to local shop.
  6. Tungstengruvsten

    Tungstengruvsten Active Member

    hmm i'd avoid that route with am-16's....you would want someone familiar with them to rack them. These are amazing sounding pre's if properly done, but lots of things can add up to less than stellar performance. I've seen some pretty sloppy jobs out there and these aren't completely intolerant to placement, shielding, etc.

    Do you have the schematics for them?? that would make it easier for someone not familiar with them to work on them, but still...

    Some things to consider:
    -mu-metal shielding for the units(as they were in the original racks)
    -star grounding within the chassis
    -internal power supply(orientation of modules and power supply can raise/lower hum/noise floor)
    -torroidal tranny for power supply(if internal)
    -external power supply if it's a small chassis
    -input pad? stepped pad attenuator?
    -proper 48v power supply and implementation(am16's are direct coupled, no caps..don't wanna fry that transformer)

    These are fixed gain amps, so there are no input/output adjustments. you will have to come up with this yourself. I've seen people use ganged pots but they don't track perfectly and this throws off the CMRR. an input attenuator with .1% resistors, maybe -10,-20,-30 positions would keep this thing sounding beautiful and allow you the flexibility to handle many different mics/instruments...
  7. Bill Park

    Bill Park Guest

    "hmm i'd avoid that route with am-16's...."

    That assumes that there is no one competent in any local shops. I want to point out that -all- shops are local somewhere. I'd have no problems taking anything to Gourmet PA, or Korby Audio, both of whom are local shops. There are also a number of good frelance techs around, like Bob Bell, Mike Mazur, Dave Long... all long-time techs, 2 with major studio experience and one who is a systems designer/engineer. Local doesn't have to mean bad.

  8. Tungstengruvsten

    Tungstengruvsten Active Member

    sorry Bill, guess when i think 'local shops' i think consumer audio repair type places...more vcr's and tv's than audio gear like am-16's.

    Heck even if they were Siemens/telefunken modules i'd have more confidence in a 'non-pro audio specific' electronics guy racking them, they are at least in mu-metal cassettes and capacitor coupled with most if not all controls already built in...

    Not alot of music stores/pro audio retailers etc around here(Toronto) offer the service of racking modules, be it eq's, pre's whatever...there are those that can do it but you gotta look....and know what you are looking for.
  9. Newatthis

    Newatthis Guest

    Thanks, Eric you make some very interesting points. Although, I would still like to find a tech or two who do have this kind of experience to compare, in order to make an educated plan.
  10. Tungstengruvsten

    Tungstengruvsten Active Member

    I can recommend a tech near here, which isn't too far from NJ but within Canada. His work is some of the best i've seen and he knows the am-16 like the back of his hand. I went through all this a year ago...did my research and after many conversations and meetings with this fellow decided on him. He racked my 4 AM-16's and has done other pair's/quads of them and other modules....really knows his stuff.

    Some things i can think of that might help:

    -get a torroidal power tranny if the power supply is going to be in the rack....i'm not big on external power supplies as it's one more thing to leave behind(i do alot of work out of town...)but the am-16's are susceptible to hum and a smaller rack could limit your placement options.

    -use .1% resistors for the input attenuator-they are expensive but worth it. I had an attenuator that had 6 positions on it...this is because I elected not to do an output control on it(which would be a passive one anyways, no gain increase)

    -put the input impedance selection on a switch...it's there!
  11. Tungstengruvsten

    Tungstengruvsten Active Member

    oh yeah and i'd post your questions down at the 'tech talk' forum...and do a search on various forums or newsgroups for 'am-16' as there are lots of posts about them over the years...

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