Members matthew13l Posted August 1, 2005 Members Share Posted August 1, 2005 Why should a guitar cabinet be raised off the floor for recording? Does it have to do with preventing low frequency absorbtion into the floor? Matt Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted August 1, 2005 Share Posted August 1, 2005 Goood - a homework assignment waiting to happen! You're close, but not quite there... so grab an amp, and set it on the floor and stick a mic on it. Note the mic position (you'll need to duplicate it later) and record a track. Now stick the same amp up on a chair, stick the same mic in the same position and re-record to a second track. Now compare the two recordings... pay particular attention to the low frequencies. What do you hear? PS - You're lucky - you should see some of the other homework assignments I've given out in the past... Link to comment Share on other sites More sharing options...
Members gtrwiz Posted August 1, 2005 Members Share Posted August 1, 2005 Hey Matt, since Phill already has you doing homework, try tilting the cab about 45 degrees and see what that does. Another question, will having an amp in the bottom part of a road case have the same effect as a chair? Or an auralex Gamma? Don't think I'm lazy, I'll be out of town for a bit and I'm curious. Link to comment Share on other sites More sharing options...
Members geek_usa Posted August 1, 2005 Members Share Posted August 1, 2005 hehe...i'll bit. by raising a guitar cab off the floor, you prevent low freq reflections from bouncing off the floor into the mic from the bottom. You'll have extra bottom end and another signal that doesn't need to be there. Link to comment Share on other sites More sharing options...
Members Kiwiburger Posted August 1, 2005 Members Share Posted August 1, 2005 I've got a different take on it ... placing a speaker closer to a wall (or floor) provides a bass boost in the room, due to exciting the room nodes more. Depending on your room, that is probably more nasty than nice. Most of us listen to our guitar cab from a few feet away, with two ears 180 degrees opposed, and 90 degrees away from the speaker cone. Contrast this with a single SM57 right up to the grill ... no comparison really. So we may as well say that the guitar player is actually listening to the room, and the mic is listening to the speaker cone. None of us actually place our ear up to the speaker cone ... So - if we have a big bassy room sound, that will be very different from what the mic is hearing. By placing the speaker on a stand, we raise it up closer to the guitar players ear. Instantly, it sounds brighter, so maybe he will adjust the treble tone to stop it being so shrill. The bass boost from the room is less, so maybe he will adjust the bass tone. Anyway - what he is hearing is now more like what the mic is hearing. I'm sure there are also issues with reflections off the floor, but I don't think that is the whole problem. Especially for the close mics. Link to comment Share on other sites More sharing options...
Members Jan Folkson Posted August 1, 2005 Members Share Posted August 1, 2005 Several companies make stands that'll get the amp up off the floor. Looks a bit less 'ghetto' than a chair and gives you the ability to adjust angles. Link to comment Share on other sites More sharing options...
Members TimmyP Posted August 2, 2005 Members Share Posted August 2, 2005 Any time a speaker is not against the room boundaries (wall, floor, ceiling) there will be total cancellation of some frequency. The frequency is dependent upon the distance from the boundary. For instance if it is 4' from a wall, there will be total cancellation at about 70Hz. (This is very handy for counteracting the 70Hz hump you get in a room with an 8' ceiling). If the speaker is 2' away, the cancellation will be at about 140Hz. See the chart at http://www.padrick.net/LiveSound/CancellationMode.htm Link to comment Share on other sites More sharing options...
Members Kiwiburger Posted August 2, 2005 Members Share Posted August 2, 2005 Interesting theory, but i'm not convinced this is a practical issue for mic'ing guitar cabs (I stand to be corrected). Most people close mic a guitar cabinet, and the close mic response should be very similar regardless of where in the room it is. As soon as you pull the mic back to get some room sound, or add multiple mic's for room sound, then the room becomes hugely important. That's where shifting a mic fractions of an inch can make a huge difference (especially with multiple mics - phase differences become extremely important). There is a world of different tones when you start moving mic's around in a room. I guess shifting the cab would also create differences, but I find it much easier to move the mic's around. I use an angled speaker stand, in the middle of an assymetrical room with an angled ceiling. Link to comment Share on other sites More sharing options...
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