Members witesol Posted June 10, 2014 Members Share Posted June 10, 2014 I've seen visual evidence that as a mic preamp's gain is raised, especially at the higher gain settings, the frequency response may be different or have some bumps.. obviously this must be design specific, with better designs having less frequency response peaks or dips, no? I realize the polar pattern will not change on a mic regardless of gain but what about the frequency response of the preamp itself? Also, are there certain areas that always tend to be problematic, in terms of GBF? Link to comment Share on other sites More sharing options...
Members dboomer Posted June 10, 2014 Members Share Posted June 10, 2014 So it shouldn't and I would suspect in most it doesn't until maybe the extreme is reached. Even then I would only expect the change to occur at the extreme ends of the frequency scale, and then only a tiny amount. GBF is all and only about gain. So the answer is if you are getting gain then you will eventually cross the threshold. Personally, I wouldn't worry about it. Typically you are probably getting 24-30 dB of gain from a preamp capable of 50-60 gain so you shouldn't be pushing it out of linearity. Link to comment Share on other sites More sharing options...
Members witesol Posted June 10, 2014 Author Members Share Posted June 10, 2014 thanks n doing some tests here at my desk on the Mbox pro mic preamp, after normalizing I expected to see the same waveforms. on higher gain settings there were some bumps...then some distortion. It's not a good preamp in spite of the "pro" name. Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 10, 2014 Members Share Posted June 10, 2014 If you are overdriving the preamp, or in your case maybe the A/D converter if that's a combination unit), you will see all kinds of bad things. Don's right, at the extremes, there may be a little droop in the response but it's unlikely to be a problem in most cases. It's in part because most gain controls change what amounts to local feedbacl of the circuit and as feedback is reduced any variations in freq. resp. will become more noticeable. Link to comment Share on other sites More sharing options...
Members witesol Posted June 10, 2014 Author Members Share Posted June 10, 2014 thanks. Checking the headroom on the A/D. the gain seems not very linear. anyhow, I had this discussing with a guy at my concert sunday and my contention was in the gain ranges I use there should not be substantial peaks..but i do not know if a lower cost preamp like a GL2400 starts to do anything at it's highest settings Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 10, 2014 Members Share Posted June 10, 2014 Probably not the issue? Link to comment Share on other sites More sharing options...
Members SoundMan Posted June 11, 2014 Members Share Posted June 11, 2014 I can think of one mixer pre-amp, that would lose all the low end when you get near the max gain. Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 11, 2014 Members Share Posted June 11, 2014 I can think of one mixer pre-amp' date=' that would lose all the low end when you get near the max gain.[/quote'] I can as well. Maybe that was a "feature"? Link to comment Share on other sites More sharing options...
Members dboomer Posted June 11, 2014 Members Share Posted June 11, 2014 I can think of one mixer pre-amp, that would lose all the low end when you get near the max gain. Me too Link to comment Share on other sites More sharing options...
Members witesol Posted June 11, 2014 Author Members Share Posted June 11, 2014 I realize my topic could include a lot of people ! I had an excellent singer saturday night at a good concert, that had the quietest voice. Another sound man who hangs out near me mentioned a tendency to feedback being higher at higher gain settings. One of the only times I thought the E835 was a better choice. Anyhow , it got me thinking... Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted June 11, 2014 CMS Author Share Posted June 11, 2014 I realize my topic could include a lot of people ! I had an excellent singer saturday night at a good concert, that had the quietest voice. Another sound man who hangs out near me mentioned a tendency to feedback being higher at higher gain settings. One of the only times I thought the E835 was a better choice. Anyhow , it got me thinking... If by "higher gain settings" he meant, "louder", then he's Captain Obvious. If he meant channel gain being higher and channel fader level lower, versus channel gain lower and channel fader level higher, then he's wrong. Link to comment Share on other sites More sharing options...
Members sibyrnes Posted June 11, 2014 Members Share Posted June 11, 2014 I can think of one mixer pre-amp, that would lose all the low end when you get near the max gain. Please share. You've aroused my curiosity! Link to comment Share on other sites More sharing options...
Members witesol Posted June 11, 2014 Author Members Share Posted June 11, 2014 how about an 80s Peavey? Link to comment Share on other sites More sharing options...
Members dboomer Posted June 11, 2014 Members Share Posted June 11, 2014 If by "higher gain settings" he meant, "louder", then he's Captain Obvious. If he meant channel gain being higher and channel fader level lower, versus channel gain lower and channel fader level higher, then he's wrong. +1 Link to comment Share on other sites More sharing options...
Members Dogoth Posted June 12, 2014 Members Share Posted June 12, 2014 I have heard other people say that you must drive a preamp reasonably hot to "get the tone out of it" also to make the EQ section work properly. I'm not sure I buy it. The only difference I've ever noticed is noise floor or distortion at the far ends of the spectrum. I suppose slightly over driving a mic pre MIGHT sound like a bit of compression and sound brighter (just the hi harmonics from that squared off top of the waveform). If it's barely clipping I guess it might be perceived as brighter before it becomes obvious distortion. Just my observations. Link to comment Share on other sites More sharing options...
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