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Isolation Box

Discussion in 'Recording' started by foul_owl, Oct 25, 2011.

  1. foul_owl

    foul_owl Active Member


    I am thinking about building one of these:
    Mike Ralph's DIY Iso Box

    And putting a 2x12 with G12K100s in it for testing. I need to be able to play loud in order to test out tube amps at full power, but not bother the neighbors. Any issues with the isolation cabinet design I should be aware of? I basically just need to make sure the tone sounds OK when the amp is running full bore. I was gonna put an SM58 inside the box and run that into a PA and then either use a headphones out from the PA or listen to it on monitors at a lower volume level.

    What would be good dimensions for the length of the box? (I was going to make the width and height slightly larger than the 2x12) Any issues you can think of I need to be aware of with an isolation box?

  2. moonbaby

    moonbaby Mmmmmm Well-Known Member

    Are you in an apartment /condo living scenario? You will still be pissing off the neighbors...LOL!
    That box looks way too flimsy to contain bass note information if you are planning to run a 50- or 100-watt tube amp "full bore". Egg crate foam and 3/4" MDF are too little to contain that sufficiently for most real-life situations. Backstage? Maybe, not at home. Do a search on this site for iso boxes, this was recently discussed, and "Space" from the "Acoustics & Studio Design" section weighed in regarding the build-up parameters necessary to control bass notes.
    Also this dude's box looks way too flimsy to be carted around to gigs. MDF held together with brackets and silicone might work in a studio, but transporting that beast will need some serious internal bracing. More weight, as if MDF isn't heavy enough.
    If testing tube amps is part of the picture, look at what Weber Amps offers in dummy loads and power attenuators. Read all you can about this. As a former speaker reconer and tube amp hacker, I can tell you they offer a lot of useful info and great products. Good luck and let us know how things work out!
  3. foul_owl

    foul_owl Active Member

    I realize it will still be loud, but at least there will be somewhat of a reduction in volume. What approx db reduction would you estimate? (At approx 10 feet from the box) I live in a house, and this will be in the basement. I just need to reduce the volume to a more manageable level. For example, a 20 db reduction or so would be great.

    I have already built a dummy load and an attenuator. Both have their uses, but the attenuator affects the tone somewhat. I'm pretty set on building this iso box, the only question is that of affecting the tone going into the mic.

    Iso box design was recently discussed on here? I will look for it.

    Thanks for the help! I will try to report on my findings eventually, but it might be a few months. :)
  4. moonbaby

    moonbaby Mmmmmm Well-Known Member

    In the basement that should work fine...I hope that you don't plan to carry it out very often!
    I didn't see any spec's on the attenuation amount. The Randall was around 40 dB, if I recall (less in the bass registers).
    Yeah, an attenuator will affect the tone in that the speakers aren't being driven as hard. What amp are you using?
  5. foul_owl

    foul_owl Active Member

    As long as the iso box won't affect the tone! I realize I won't get the sound of the room, but I'm totally fine with that.

    Amp is my own design. High gain preamp, two channel, fx loop, 100 watt push pull fixed bias power amp.

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