Isolating drums

[Richard Rupert]

Got it thanks. The separation question was with regards to the results - which at 4" seems would give you pretty distinct toms (assuming the edge pointed between them). Is this rig the predominant cymbals mics too?

I'm trying to wrap my head around how this works as lower frequencies round corners somewhat - and at the same time the board could also act as an acoustic component too. I imagine it imparts a music element of its own on things - but I suppose anything you use does...

On one of my guitars, I have an LR Baggs pickup mounted in the soundhole. The body of the pickup's motion is supposed to capture some of the acoustic sound somehow - like the polepieces are allowed to move in relation to the voicecoil via a suspension mount. It isn't the best pickup*, but still an okay sound - and the newer models are said to sound better.

* edit: I'm not saying it isn't a decent pickup. I think it's only been in a old ('73?) Guild D50 - which while a fantastic guitar, is darker sounding with not nearly as much soundboard movement as more contemporary dreadnoughts. It's the mechanical movement that gives the pickup its acousticy character, so I may not have experienced it in optimum conditions.

Just to be clear... the PZMs are 4 feet above the toms, not 4 inches. And the intended primary use of these mics is as overheads; they do pick up toms too, but their primary capture source are the cymbals, with just a general overall picture of the drums. I mic all drums individually as well... 9 mics in all counting the Crown PZMs -- kick, snare top and bottom, 3 toms and hat. I do get a good stereo image from the PZMs.

[Richard Rupert]

Richard, I'm thinking maybe I don't understand PZM mics after all. Having no experience with them but having read for just a few minutes, I was under the impression that they receive pressure wave differences via the surface they are in contact with. That left me thinking that the surface vibrates and the PZM 'hears' it. How do your two overhead PZMs differentiate between toms if they are attached to opposite sides of the same board? Or am I getting that wrong?

Yeah, I don't think that's right. I get good separation. These mics are condensers with a very small opening for the capsule to pick up sound waves. They don't suffer from phase issues like other mics. I'm sure there's a lot of info on line about the technology. I just know they work for my intended purpose.

[Richard Rupert]

https://www.sweetwater.com/insync/pz...by-sweetwater/

Yes, yes, yes... that's the ticket. Couldn't have said it better myself. Actually, I couldn't have said it as well.

[Naturally Digital]

Richard, I'm thinking maybe I don't understand PZM mics after all. Having no experience with them but having read for just a few minutes, I was under the impression that they receive pressure wave differences via the surface they are in contact with. That left me thinking that the surface vibrates and the PZM 'hears' it. How do your two overhead PZMs differentiate between toms if they are attached to opposite sides of the same board? Or am I getting that wrong?

It's a variation on this technique:

(shamelessly grabbed from this excellent site):

Apologies for the size of the image.

The Wedge technique

In this technique two boundary microphones (also called pressure zone microphones or PZMs) are mounted on a V-shaped wedge, about 15 cm (6 inches) from the tip of the V. The point of the wedge is aimed at the music source.

The wedge consists of two square panels approximately 60 cm (2 feet) on each side and joined together on one side to form a V with an angle of 70°.²⁷ In the 1990s, Crown Audio further developed this concept with a patented design they call a Stereo Ambient Sampling System (SASS). It uses a two PZMs mounted on each side of an angled, flat surface with a foam baffle in between. This technique creates a realistic sounding, well-focused, natural stereo image with good spatial localization. It is also very good at capturing ambient sounds. Because the capsules are close together, there is little phase cancellation which produces good mono compatibility.²⁸

Summary

There are numerous stereo microphone techniques, some with subtle differences, to choose from. The best choice for a given situation will depend on many factors, such whether the performance is to be broadcast or recorded, the size of the performing group, restrictions of the venue, the presence or absence of an audience, the acoustics of the performance hall, and what microphones you have available. If the goal is to produce a recording with a realistic and spacious stereo image, then the first choice would be the Decca tree. If you have only two microphones or if venue limitations prevent its use, then spaced omnis would be a good choice. If audience noises or acoustics are a problem, the make it a spaced cardioid.


If absolute mono compatibility is essential, then the M-S technique should be considered. This method also gives you the greatest flexibility when you get back to the studio to mix the recording. If that technique is not feasible for some reason, then the Blumlein pair is a good choice, except in noisy situations or in venues with poor acoustics. In that case, the X-Y method should be used.

If a better stereo image is desired and some compromise can be made on mono compatibility, then one of the near-coincident techniques should be the choice. Whatever configuration is picked, some experimentation is in order. You can adjust the spacing and angle of the microphones a little at a time until you obtain the desired effect and best stereo image.

Whatever the choice, keep in mind that these are tried and true techniques and many great recordings have been made using them.³⁶

For a table summarizing these techniques, go to Stereo Microphone Techniques.

Last update: 08/10/2018