basspig
Veteran
I’ve done some recording out in the field with the PMW-EX1 and have made some observations about the gain staging setup used internal to the camera and how to set the attenuators to achieve the best dynamic range out of the camera.
My stereo mic of choice is the Rode NT4. Last Saturday, I recorded the Kent Singers, a choir group of 20 singers, accompanied by piano and guitar, in a small New England church.
The Rode NT4 has a sensitivity of -38dBv. Given this, I set the EX1’s attenuators for -38dB, as a starting point.
I found that on a lively number, the choir’s SPL at 12’ was sufficient to not only hit the limiters, but to achieve some clipping, where the limiters were not fast enough.
I backed off the attenuator settings by 6dB for each channel and that seemed to free the system from dynamic compression and clipping. However, during applause segments, heavy limiting was audible.
I discovered with studio testing with a very loud sound system, that a setting of -11dB on the mic attenuators would allow recording of the loudest live music/bands in existence without any clipping or compression.
GAIN STAGING:
There evidently are TWO limiters in the EX1: One appears just downstream of the attenuators; the other downstream of the record level controls.
This can be observed by feeding signal to the camera’s input jacks at gradually-increasing levels, while the record levels are set to 5. At some point, the sound will start to take on a “broadcast on the radio” quality, as the dynamics will be flattened out. Turning down the record level won’t change this compression effect, though it will reduce the record level going on to the SxS card.
The only way to remove the effects of the input limiter is to increase the amount of input attenuation. The smaller the number, the greater the attenuation. The numbers refer to the signal level that is needed to be present to achieve a reference recording level. Since they are negative numbers, smaller is bigger. By increasing the attenuator setting (so it is less sensitive) the signal peaks will be reduced below the limiter threshold and the sound will pass pretty much un-altered.
Even if you set the attenuation correctly, you can still hit a secondary limiter if your record level is too high. I find that a setting of 5 is optimal. Any higher than 6 and there will be an increase in the noise floor. If you need more gain to record quiet content, like nature sounds, it is more effective to reduce input attenuation than to turn up the record gain.
An observation about the Auto gain control setting: it completely ignores your input attenuator settings. The camera will not be able to handle high SPL situations in Auto. Use Manual gain and set levels conservatively. You can always normalize in post, but you can’t fix badly-compressed and clipped audio in post.
In conclusion, if you want to get the most out of the audio system on the EX1, you must set both the attenuators AND the record gain appropriately for the situation.
Here are my suggestions, vis-à-vis the Rode NT4 (dB SPL levels are peak, not average):
With careful adjustment for the given situation, the EX1 can provide near-audiophile-quality recordings of musical, pyrotechnic and natural sound events without the need for separate audio recording methods.
My stereo mic of choice is the Rode NT4. Last Saturday, I recorded the Kent Singers, a choir group of 20 singers, accompanied by piano and guitar, in a small New England church.
The Rode NT4 has a sensitivity of -38dBv. Given this, I set the EX1’s attenuators for -38dB, as a starting point.
I found that on a lively number, the choir’s SPL at 12’ was sufficient to not only hit the limiters, but to achieve some clipping, where the limiters were not fast enough.
I backed off the attenuator settings by 6dB for each channel and that seemed to free the system from dynamic compression and clipping. However, during applause segments, heavy limiting was audible.
I discovered with studio testing with a very loud sound system, that a setting of -11dB on the mic attenuators would allow recording of the loudest live music/bands in existence without any clipping or compression.
GAIN STAGING:
There evidently are TWO limiters in the EX1: One appears just downstream of the attenuators; the other downstream of the record level controls.
This can be observed by feeding signal to the camera’s input jacks at gradually-increasing levels, while the record levels are set to 5. At some point, the sound will start to take on a “broadcast on the radio” quality, as the dynamics will be flattened out. Turning down the record level won’t change this compression effect, though it will reduce the record level going on to the SxS card.
The only way to remove the effects of the input limiter is to increase the amount of input attenuation. The smaller the number, the greater the attenuation. The numbers refer to the signal level that is needed to be present to achieve a reference recording level. Since they are negative numbers, smaller is bigger. By increasing the attenuator setting (so it is less sensitive) the signal peaks will be reduced below the limiter threshold and the sound will pass pretty much un-altered.
Even if you set the attenuation correctly, you can still hit a secondary limiter if your record level is too high. I find that a setting of 5 is optimal. Any higher than 6 and there will be an increase in the noise floor. If you need more gain to record quiet content, like nature sounds, it is more effective to reduce input attenuation than to turn up the record gain.
An observation about the Auto gain control setting: it completely ignores your input attenuator settings. The camera will not be able to handle high SPL situations in Auto. Use Manual gain and set levels conservatively. You can always normalize in post, but you can’t fix badly-compressed and clipped audio in post.
In conclusion, if you want to get the most out of the audio system on the EX1, you must set both the attenuators AND the record gain appropriately for the situation.
Here are my suggestions, vis-à-vis the Rode NT4 (dB SPL levels are peak, not average):
Quiet nature scenes, SPLs under 70dB. Set attenuator for -38dB (good to 106dB)
Small acoustic or singing ensembles. Set attenuator for -32 or -29dB (good to 115dB)
Jazz ensembles with moderate amplification. Set for -23 or -20dB (good to 124dB)
Loud disco or rock band concerts. Set for -14 or -11dB (good to 133dB SPL)
Fireworks should use the -14dB range, if you’re close enough to need earplugs.
Record level of 5 will pretty much provide full-scale (full scale without limiting is 3 dots short of the red dot on the EX1’s audio level meter scale). A level of 6 will push things toward more limiting on the secondary limiter stage and a little more hiss from the preamp. 5 is really pretty optimal, with adjustments to attenuators for expected maximum SPL.Small acoustic or singing ensembles. Set attenuator for -32 or -29dB (good to 115dB)
Jazz ensembles with moderate amplification. Set for -23 or -20dB (good to 124dB)
Loud disco or rock band concerts. Set for -14 or -11dB (good to 133dB SPL)
Fireworks should use the -14dB range, if you’re close enough to need earplugs.
With careful adjustment for the given situation, the EX1 can provide near-audiophile-quality recordings of musical, pyrotechnic and natural sound events without the need for separate audio recording methods.
But of course such low frequencies can pop out of nowhere, especially passing cars modded by males of less than 30 years. And they travel long distances (from band rehearsals in the same venue).