Recording a snare drum, there's such a difference in timbre between the sound outside the skin and within the drum that it is conventional to place two microphones, one either side of the skin, and adjust relative levels to produce the required sound.
To avoid bass cancellation, one microphone must have its polarity inverted. Which one? And why?
This is not intended to be a trick question. If we can't answer this question, then absolute phase has to be questioned as being an anomaly in the replay system. Perhaps air linearity in small boxes...
To avoid bass cancellation, one microphone must have its polarity inverted. Which one? And why?
This is not intended to be a trick question. If we can't answer this question, then absolute phase has to be questioned as being an anomaly in the replay system. Perhaps air linearity in small boxes...
I'd be prepared to put money [well, a fiver (£5), anyway] on most recording engineers inverting the inside microphone. Which, in a way, proves my point. You have presented a logical argument, yet I'm fairly sure it's ignored.
[edit] The distance the skin moves is the same, whichever side we observe...
[edit] The distance the skin moves is the same, whichever side we observe...
First, I think this is a wrong forum or at least wrong area of the forum ( Tubes?) to ask this question.
Second, there is no single correct answer to the problem.
As a recording engineer who used this technique a lot I can tell you that every snare drum responds a bit different to this way of miking. Depending on the depth of the drum itself, relative and absolute tuning of both heads and playing technique of the drummer the results of flipping the polarity of the bottom mic can be perceived as an improvement, change for worse, or just a change without a clear favorite. Also, changing the relative level of the bottom mic will sometimes change the prefered polarity setting.
The textbook/recording school method is to match both mics in level and the polarity that results in fuller sound is the correct one. Then adjust the bottom mic's level to taste. The problem is that sometimes it is impossible to tell which setting is fuller. They both sound bad or good or just different. Also, remember that 99% of the time snare mic is just one of many picking up snare's sound. Highly compressed overhead mics and room mics can carry more information about the snare in the final mix than the dedicated snare mic(s). If you consider that those can be delayed anywhere from 5-15 msec. (due to sound propagation delay) in relation to the close mic, the comb filtering effect can be greater than anything resulting from interaction of the top and bottom mic on the snare drum.
As to absolute polarity with regard to snare drum, on an isolated sample it could be audible, but the distinction could be easilly lost depending on positioning of the close mic.
Second, there is no single correct answer to the problem.
As a recording engineer who used this technique a lot I can tell you that every snare drum responds a bit different to this way of miking. Depending on the depth of the drum itself, relative and absolute tuning of both heads and playing technique of the drummer the results of flipping the polarity of the bottom mic can be perceived as an improvement, change for worse, or just a change without a clear favorite. Also, changing the relative level of the bottom mic will sometimes change the prefered polarity setting.
The textbook/recording school method is to match both mics in level and the polarity that results in fuller sound is the correct one. Then adjust the bottom mic's level to taste. The problem is that sometimes it is impossible to tell which setting is fuller. They both sound bad or good or just different. Also, remember that 99% of the time snare mic is just one of many picking up snare's sound. Highly compressed overhead mics and room mics can carry more information about the snare in the final mix than the dedicated snare mic(s). If you consider that those can be delayed anywhere from 5-15 msec. (due to sound propagation delay) in relation to the close mic, the comb filtering effect can be greater than anything resulting from interaction of the top and bottom mic on the snare drum.
As to absolute polarity with regard to snare drum, on an isolated sample it could be audible, but the distinction could be easilly lost depending on positioning of the close mic.
Blumlein rules OK! Yet...
But most recordings are multi-miked, so...
Does anyone have any idea of the proportion of genuine Blumlein recordings using a pair of "figure of eight" crossed microphones that have been made, compared to the multi-miked stuff?
The Decca "tree" technique definitely didn't meet the Blumlein criterion, but it produced some cracking recordings.
But most recordings are multi-miked, so...
Does anyone have any idea of the proportion of genuine Blumlein recordings using a pair of "figure of eight" crossed microphones that have been made, compared to the multi-miked stuff?
The Decca "tree" technique definitely didn't meet the Blumlein criterion, but it produced some cracking recordings.
Well, from an engineers viewpoint, when I mic the underside of a snare it is to pick up the snares as well as a different bit of tone. I may or may not invert the bottom mic depending on how it sounded. Phase would have nothing to do with it depending on the mic's that are used. SM57's are rear rejecting mic's and are what I normally use on a snare. Through proper placement phase problems can be avoided as the mic's are not picking up the same thing yet their diaphrams are reacting in the same direction at the instant of the hit. The bottom mic is for a slight tonal change only and will not represent the overall snare sound. As for placing a mic inside the shell, the tone is different inside the shell but you are now recording the same skin. There again it would be a toss up as to wether I would invert or not, depends on how it sounded. Here again the mic's diaphrams are both reacting in the same direction at the same time, the only difference being the tone inside the shell. It always boils down to how it sounds and the individuals taste. Where you run into phasing problems on a drum kit are with the overheads. If you ever hear flanging in the cymbals then mic placement is to blame. Placement would be the cure however, and not the phase button.
I realize I have not addressed the phase issue as you may have liked, just a bit of perspective from an engineer.
I realize I have not addressed the phase issue as you may have liked, just a bit of perspective from an engineer.
Polarity for the listener to the recording?
I agree, although I would point out that you replied to the post.
It looks as though a "recording" section on the forum might be needed.
Coming back to the polarity question, it looks as though it could be random? I'm really not trying to be a smart-****.
Thunau said:
I agree, although I would point out that you replied to the post.
It looks as though a "recording" section on the forum might be needed.
Coming back to the polarity question, it looks as though it could be random? I'm really not trying to be a smart-****.
Re: Polarity for the listener to the recording?
I just happened to look at the front page at the right time. 5 minutes later and you would have missed my input (as if anybody cared
).
Everything Else would be a good section to post this topic. I look there regularly.
EC8010 said:
I agree, although I would point out that you replied to the post.
It looks as though a "recording" section on the forum might be needed.
I just happened to look at the front page at the right time. 5 minutes later and you would have missed my input (as if anybody cared
).Everything Else would be a good section to post this topic. I look there regularly.
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