Members mgray Posted February 6, 2010 Members Share Posted February 6, 2010 I know it's best to have the instrument and the sound coming out of the amp "in phase", but how do I know when I'm in proper phase? I have a hard time hearing the difference. Also, if I'm getting bad feedback, and I push the phase button to stop it, am I now out of phase and is my sound suffering? Ie. If I have an amp that is always giving me feedback, and I have to push the phase button to stop it, am I now out of phase and is my sound going to suffer? Link to comment Share on other sites More sharing options...
Members TimmyP Posted February 6, 2010 Members Share Posted February 6, 2010 The difference can be pretty subtle, especially on mic'd instruments, as you have two arrival times (sound from the instrument and sound from the PA). On kick, I use which ever setting has more felt impact. On guitar, I use which ever setting has more "body". If you can't hear a difference and reversing the polarity solves a problem that you cannot solve another way (or if the other way sounds worse), then reverse away :-) Link to comment Share on other sites More sharing options...
Members dboomer Posted February 6, 2010 Members Share Posted February 6, 2010 You are actually talking about "polarity" and not "phase" because if you run through an amp and make any change to EQ you will have changed the phase. The polarity just means whether the initial movement of the wave started up or started moving down. By itself it means nothing. It's like asking is ot hot or cold ... you have to compare it to something else. Short answer ... if you don't hear it don't worry about it. If you have the opportunity to flip it then listen to it both ways and if you think you can hear a difference leave it the way it sounds best. It won't hurt anything either way. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 6, 2010 Members Share Posted February 6, 2010 On acoustic amps, a polarity switch is common because often that's the best and only practical way to resolve sympathetic vibration causing feedback on an acoustic instrument. Eq is another tool, but polarity is the first choice IMO. Link to comment Share on other sites More sharing options...
Members mgray Posted February 6, 2010 Author Members Share Posted February 6, 2010 On acoustic amps, a polarity switch is common because often that's the best and only practical way to resolve sympathetic vibration causing feedback on an acoustic instrument. Is "sympathetic vibration" the same as natural body resonance frequency? So even if I'm not playing the guitar, if gain gets too high, it will start to feedback at that frequency? Also, if I have 2 phase buttons in my chain(one on the preamp, one on the amp) is there one which I should go for first? Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 7, 2010 Members Share Posted February 7, 2010 Also, if I have 2 phase buttons in my chain(one on the preamp, one on the amp) is there one which I should go for first? Either one, they do exactly the same thing. Only switch one though, if you switch both you will be right back to where you started. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted February 7, 2010 Members Share Posted February 7, 2010 It is when feedback begins to happen. Sympathetic vibration is caused when the sound waves are inphase with those generated by the body ofthe instrument when picked up by the pickup. Translation: Yes Either one, they do exactly the same thing. Only switch one though, if you switch both you will be right back to where you started. Not exactly, if you have one of those pickup systems that mixes piezo and internal mic. In that case the switch on the pickup preamp might be switching one and not the other. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 7, 2010 Members Share Posted February 7, 2010 The natural body resonance is what ALLOWS sympathetic vibration, provided the other factors I mentioned are in place. Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 7, 2010 Members Share Posted February 7, 2010 Not exactly, if you have one of those pickup systems that mixes piezo and internal mic. In that case the switch on the pickup preamp might be switching one and not the other. I figured he was using a simple pickup, not something more complex, but yes, if there are 2 pickup sources involved, it's possible that only one is being inverted. Link to comment Share on other sites More sharing options...
Members TimmyP Posted February 8, 2010 Members Share Posted February 8, 2010 I should add that whenever I have someone playing an acoustic instrument, I give them an A-B between normal and reverse polarity in their monitor (without telling them what I'm doing). IIRC, there's not been anyone who failed to express a preference. Link to comment Share on other sites More sharing options...
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