NB. For the avoidance of doubt my budget would never extend to Schoeps, Neumann or DPA.
![Smile :)](./files/images/smilies/icon_e_smile.gif)
I thank you.
Mike Stranks wrote: ↑Wed Feb 23, 2022 10:29 pm In a recent thread Hugh pointed out that the LineAudio OM1 is designed for near-field use. As most of my work needing omnis is far-field, can anyone recommend some good, budget omni far-field/diffuse field mics?
NB. For the avoidance of doubt my budget would never extend to Schoeps, Neumann or DPA.
I thank you.
Trevor Johnson wrote: ↑Thu Feb 24, 2022 10:17 am If you want the Oktava, I'd buy them whilst you still can.
Hugh Robjohns wrote: ↑Thu Feb 24, 2022 12:49 pm The Acoustic Pressure Equaliser -- APE -- or the sphere/ball attachment for some omni mics modifies both the frequency and polar responses, with the aim of enhancing on-axis clarity and subduing the off-axis ambience.
It does add brightness to on-axis sources through a pressure build-up effect but, more importantly, it also alters the direct/reverberation ratio, reducing the level of high frequency sound arriving off-axis. This is used, essentially, to give better stereo imaging in reverberant spaces.
Increasing the size of the sphere results in the effect working down to a lower frequency (and vice versa). Most sphere's are about 40mm, but they can range from 30-50mm.
It does a completely different thing to diffuse-field equalisation which is intended to ensure equal sensitivity and frequency response for both on and off-axis sounds.
EQ will obviously affect both on-axis and off-axis sources equally.
In contrast the near-field/diffuse-field equalisation is intended to compensate for a physical effect that occurs only with close on-axis sources.
In practice, you can boost the HF of a direct-field omni (flat for close on-axis sources) when used in the diffuse-field to restore a reasonably natural spectral balance.
Going the other way, cutting the HF of a diffuse-field omni to restore the tonal balance of a close on-axis source will also result in any off-axis spill sounding duller. Whether that's an issue depends on the circumstances, of course. A better option in this situation is simply to orient the mic so that sound from the wanted close source arrives side-on to the capsule (at 90 degrees) since this doesn't result in an on-axis pressure build-up and thus no HF peak!
Hugh Robjohns wrote: ↑Thu Feb 24, 2022 12:49 pm The Acoustic Pressure Equaliser… does add brightness to on-axis sources through a pressure build-up effect but, more importantly, it also alters the direct/reverberation ratio, reducing the level of high frequency sound arriving off-axis.
…diffuse-field equalisation which is intended to ensure equal sensitivity and frequency response for both on and off-axis sounds.
doesn’t result in an on-axis pressure build-up and thus no HF peak!
Aled Hughes wrote: ↑Thu Feb 24, 2022 10:10 pm...be very similar to the HF boost built into mics such as the KM183, which must be a directional boost seeing that the mics do not exhibit it at 90 degrees?
think I’m missing or ignoring something fundamental here…
Aled Hughes wrote: ↑Fri Feb 25, 2022 11:41 am So the 90 degree placement ‘trick’ only works for close sources?
It would make no difference whether the mics were pointing forward or upward in the diffuse field?
Hugh Robjohns wrote: ↑Fri Feb 25, 2022 11:44 amAled Hughes wrote: ↑Fri Feb 25, 2022 11:41 am So the 90 degree placement ‘trick’ only works for close sources?
Correct.