Members 80zboy Posted November 27, 2003 Members Share Posted November 27, 2003 I'm amazed and pleased if this is true, but... With my Mackie CFX20 mixer, I had to EQ the hell out of our practice space or we had feedback up the ying yang. I never thought that the mixer could be a part of the problem. With the new Allen & Heath GL2000, I only had to dip 3 freqs and there was no feedback... EVEN though we were actually louder than usual?! Is it possible that the board can make such a difference when it comes to feedback? Link to comment Share on other sites More sharing options...
Members theelmsrock Posted November 27, 2003 Members Share Posted November 27, 2003 Thats kind of like saying: "My 87 S10 blazer with the 2.8 V6 wouldn't hardly pull that trailer up that hill without struggling and sputtering, but my new Dodge Ram 2500 cummins diesel does it with no problems." The CFX mixers aren't worth they're weight in the plastic that's in them. Link to comment Share on other sites More sharing options...
Members 80zboy Posted November 28, 2003 Author Members Share Posted November 28, 2003 OK, well with that first question answered, the question that now begs an answer is WHY? I just don't understand what a mixer has to do with feedback. I can understand the mics making a difference, or the monitors and monitor placement or the eq section on the mixer... but never in my time perusing this forum have I ever seen, as a cure for feedback problems, "get a better mixer." Please explain why a mixer can cause feedback problems. The example of the trucks is very nice, but does not exactly explain the problem. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 28, 2003 Members Share Posted November 28, 2003 Originally posted by 80zboy OK, well with that first question answered, the question that now begs an answer is WHY?I just don't understand what a mixer has to do with feedback. I can understand the mics making a difference, or the monitors and monitor placemen or the eq section on the mixert... but never in my time perusing this forum have I ever seen as a cure for feedback problems, "get a better mixer."Please explain why a mixer can cause feedback problems. The example of the trucks is very nice, but does not exactly explain the problem. I also do not see a good reason for the miraclous feedback cure! It's possible that the new mixer was operated at a lower overall gain, which will have this effect. The same effect could be achieved by turning down the overall volume of the first console. All of this assumes that there was no compression being used, identical eq amounts (not just knob positions) and identical oveall gain between first and second board. Link to comment Share on other sites More sharing options...
Members 80zboy Posted November 28, 2003 Author Members Share Posted November 28, 2003 Originally posted by agedhorse I also do not see a good reason for the miraclous feedback cure!It's possible that the new mixer was operated at a lower overall gain, which will have this effect. The same effect could be achieved by turning down the overall volume of the first console.Well... I always run the main fader at Unity Gain, so unless there is a difference between the two mixer's unity level then I ran them the same.All of this assumes that there was no compression being used, identical eq amounts (not just knob positions) and identical oveall gain between first and second board. things that make you say hmmmmm. Link to comment Share on other sites More sharing options...
Members J Kylez Posted November 28, 2003 Members Share Posted November 28, 2003 One thing that seems to induce problems from those boards is the use of the onboard EQ and then the outboard EQ. Link to comment Share on other sites More sharing options...
Members 80zboy Posted November 28, 2003 Author Members Share Posted November 28, 2003 Originally posted by J Kylez One thing that seems to induce problems from those boards is the use of the onboard EQ and then the outboard EQ. If you're referring to the 9 band graphic eq... I left those faders all at the default midline as I had the much superior 31 band outboard eq. Perhaps the 9 band eq causes a problem anyway? Link to comment Share on other sites More sharing options...
Members J Kylez Posted November 28, 2003 Members Share Posted November 28, 2003 I think it colors the sound anyway. I wish it had a bypass button. Then you would know it's out of the signal path. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 29, 2003 Members Share Posted November 29, 2003 Each manufacturer chooses their "nominal" levels based on their individual architecture. Therefore, you can not reliably elect one "nominal" over another. Same goes for the incorrect application of the term "unity". The only way to make such a comparison is to send a signal to both consoles and calibrate the gain paths to be exactly the same for each console. You may be surprised at how different things can look. Link to comment Share on other sites More sharing options...
Members whsjosh Posted November 29, 2003 Members Share Posted November 29, 2003 CFX's low headroom could be the problem. Also CFXs have its own colored sound (sort of slightly distorted sound). And more, the signal level of aux outs on CFX is low. You have to push more and more. These things might caused the chain-reaction... I had the CFX20 once a while then I've upgraded to Venice a few month ago. Our sound is now in completely different world. Better sound, better EQ, bigger headroom... But I don't notice any feedback issue like 80zboy says. Maybe because we don't play so loud (FOH & MON). Yoshi Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 29, 2003 Members Share Posted November 29, 2003 Even the pot taper will affect what is perceive as headroom, operating levels etc just due to the different knob position and feel (rate of change). Link to comment Share on other sites More sharing options...
Members 80zboy Posted December 1, 2003 Author Members Share Posted December 1, 2003 Just as a follow -up: We played a two nighter this weekend in a place we've played many times before. We have always had a problem with monitor feedback there. This weekend, we had NO troubles with monitor feedback! My sound man gave me a long explaination that I understood little of, but essentially, he said it was to do with the channel EQ's being so much higher quality. That make sense to everyone? Link to comment Share on other sites More sharing options...
Members sirdaniel Posted December 1, 2003 Members Share Posted December 1, 2003 that's all BS. Feedback is feedback.a parametric eq is the epitome of feedback killers.MONEY can buy solutions, but isn't it funner when you can cure a problem without writing a big check. Like buying a way more expensive mixer.Channel eq's are NOT the answer. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted December 1, 2003 CMS Author Share Posted December 1, 2003 Originally posted by sirdaniel that's all BS. Feedback is feedback.a parametric eq is the epitome of feedback killers.MONEY can buy solutions, but isn't it funner when you can cure a problem without writing a big check. Like buying a way more expensive mixer.Channel eq's are NOT the answer. Since you're so sure of yourself; what IS the answer? Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 1, 2003 Members Share Posted December 1, 2003 Count one vote for knowledge and experience! Link to comment Share on other sites More sharing options...
Members 80zboy Posted December 1, 2003 Author Members Share Posted December 1, 2003 Originally posted by sirdaniel that's all BS. Feedback is feedback.a parametric eq is the epitome of feedback killers.MONEY can buy solutions, but isn't it funner when you can cure a problem without writing a big check. Like buying a way more expensive mixer.Channel eq's are NOT the answer. I bought it second hand so I didn't really have to write THE BIG CHECK. Once I sell my Mackie, it should be pretty close to a wash. The issue here is that the only thing that has changed is the board. Same mics, same eq's, same musicians, same monitors. It's been a huge difference. I'm NOT saying that we weren't able to deal with the feedback before... it was just always an issue. Since including the new mixer in the ... mix... it hasn't really even been a consideration. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted December 1, 2003 CMS Author Share Posted December 1, 2003 Originally posted by 80zboy I bought it second hand so I didn't really have to write THE BIG CHECK. Once I sell my Mackie, it should be pretty close to a wash.The issue here is that the only thing that has changed is the board. Same mics, same eq's, same musicians, same monitors. It's been a huge difference. I'm NOT saying that we weren't able to deal with the feedback before... it was just always an issue. Since including the new mixer in the ... mix... it hasn't really even been a consideration. You don't need to explain or justify your purchase.....I think there's only one person who didn't understand that you were merely mentioning a happy coincidence and seeking an explanation for it. Link to comment Share on other sites More sharing options...
Members sirdaniel Posted December 1, 2003 Members Share Posted December 1, 2003 a parametric eq is usually the handiest tool in the toolbox. but real world experience is the best. Mic selection, placement are tops too... Link to comment Share on other sites More sharing options...
Members Audioeast Posted December 1, 2003 Members Share Posted December 1, 2003 Originally posted by 80zboy I bought it second hand so I didn't really have to write THE BIG CHECK. Once I sell my Mackie, it should be pretty close to a wash.The issue here is that the only thing that has changed is the board. Same mics, same eq's, same musicians, same monitors. It's been a huge difference. I'm NOT saying that we weren't able to deal with the feedback before... it was just always an issue. Since including the new mixer in the ... mix... it hasn't really even been a consideration. I think the quick anwser is the A&H has far better preamps, bussing system, more utilitys for eliminating the bad (such as feedback and poor tone) When you pull out a frequency on the A&H all the other freqs dont go with it because the bandwidth (Q) of the Eq is tighter than on the CFX With cfx - when you cut a frequency out it pulls alot of other freqs around it with the one you intended - so you lose volume, so then you add more gain and so on....bad filters, bad bussing system, bad design = bad sound nice upgrade and congrats......... Link to comment Share on other sites More sharing options...
Members 80zboy Posted December 1, 2003 Author Members Share Posted December 1, 2003 Originally posted by Audioeast I think the quick anwser is the A&H has far better preamps, bussing system, more utilitys for eliminating the bad (such as feedback and poor tone) When you pull out a frequency on the A&H all the other freqs dont go with it because the bandwidth (Q) of the Eq is tighter than on the CFXWith cfx - when you cut a frequency out it pulls alot of other freqs around it with the one you intended - so you lose volume, so then you add more gain and so on....bad filters, bad bussing system, bad design = bad sound nice upgrade and congrats......... Great reply and... thanks. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted December 1, 2003 Members Share Posted December 1, 2003 I've been brooding over this "better EQ gives better gain before feedback" concept today, and I've got a bit of a theory. Maybe a couple theories, actually. Theory #1 is that the engineer is able to use the more controlled EQ to pull out problem areas on specifics inputs. I've certainly done this, and with good EQ it can help a lot. Theory #2 is that with cheap EQ the "flat" positions might not be especially flat. More expensive EQ designs often use center-tapped gain knobs so that in the center (detent) position the EQ circuit can be disabled automatically. Either or both are likely. Link to comment Share on other sites More sharing options...
Members 80zboy Posted December 1, 2003 Author Members Share Posted December 1, 2003 Originally posted by Scodiddly I've been brooding over this "better EQ gives better gain before feedback" concept today, and I've got a bit of a theory. Maybe a couple theories, actually.Theory #1 is that the engineer is able to use the more controlled EQ to pull out problem areas on specifics inputs. I've certainly done this, and with good EQ it can help a lot.Theory #2 is that with cheap EQ the "flat" positions might not be especially flat. More expensive EQ designs often use center-tapped gain knobs so that in the center (detent) position the EQ circuit can be disabled automatically.Either or both are likely. It might be important for you to understand that the feedback problems occured with the channel eq's in the "flat" position. All the feedback issues were BEFORE tweaking. Similarly, with the A&H, the channel eq's were all in the flat position. When I mentioned that I only had to tweak 3 freqs, I was referring to the 31 band outboard graphic EQ. Theory #2 is interesting... and might just apply to this situation. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted December 2, 2003 Members Share Posted December 2, 2003 Theory #3: The old mixer had pre-EQ monitor sends, and the A&H has post-EQ. Sound guy dials out problem frequency in mains, and now it's also gone from monitors. Hmm... but if the EQ wasn't used, then this theory doesn't seem to apply to this particular case. Link to comment Share on other sites More sharing options...
Members agedhorse Posted December 3, 2003 Members Share Posted December 3, 2003 Was the gain (actual gain not the knob position) the same? Link to comment Share on other sites More sharing options...
Members whsjosh Posted December 3, 2003 Members Share Posted December 3, 2003 Scodiddly, CFXs have post EQ monitor send .... Link to comment Share on other sites More sharing options...
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