Thanks for the feedback Marcel!
Now one need to learn how to place the mics also
Improvements to be considered:
And the question about the TI based AD.... resurrect or abandon... would it be better or worse?
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Now one need to learn how to place the mics also
Improvements to be considered:
- Find out whole recording system linearity and make a compensation process
- Better mic / disc stand incl. mic holder
- Galvanic isolator for USB connection to ADC inc. battery feed to ADC. Saw some German product - a bit pricy...
- An additional, even more portable and easier/quicker mic stand for "street photo" style recordings.
And the question about the TI based AD.... resurrect or abandon... would it be better or worse?
//
On the recording above there is some wind induced LF swooshing at times. It was very calm until the bells started to ring of course one can hear the snow that came down the last 2 days is starting to melt and drip. I had no wind sheilds at this time. Thinking about something but the "field" I have in mind is not outdoor so much so really no bug issue for me. But an effective shield for the odd bird and marching band could come in handy
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one can hear the snow that came down the last 2 days is starting to melt and drip. I had no wind sheilds at this time. Thinking about something but the "field" I have in mind is not outdoor so much so really no bug issue for me. But an effective shield for the odd bird and marching band could come in handy //
So now I feel being in the end of the build of a recording system
At least the electrical aspects of it - I might improve some of the mobility aspects of the gear but now it is absolutely usable and sound fine.
I made a new organ recording today in the same church as before. Check out the attachments.... its probably the last for a while - they are fed up with me I think :-D
There are some modifications made since the last organ recording:
You can hear a short 24/44 excerpt by download the attachment.
Next occasion to use UGFR is at the swedish prince birthday and the 21 shot salute fired not long away from where I live. I have a bit of problem with this - I wonder how loud it is gonna get. And where to place the mics? How far and direction?
Here is the equipment for the salut: https://sv.wikipedia.org/wiki/57_mm_kanon_M/89
Here is the place: https://www.kungligaslotten.se/arti...slotten/2020-06-05-en-hogtidlig-halsning.html
Overview picture of site: https://www.kungahuset.se/images/18...0430_salut_Skeppsholmen_foto_H_Garlov_952.jpg
I used my SPL meter at todays recording - it showed 84 dBA during the last 3 second push - it can be heard in the end of flac download.
The statistics for that 3 sec part:
The recording you listen to has been amplified 5x6 dB = 30 dB. This is my headroom if I dont change the sensitivity strapping on the Comos ADC. It's now on the most sensitive, 1,7V. The mic is fed 5V. No gain in the mic. There is a setting for 6,7V - thats appr. 9 dB lower sensitivity. Perhaps that needed. Canons are loud...
Mic:
What say you?
//
At least the electrical aspects of it - I might improve some of the mobility aspects of the gear but now it is absolutely usable and sound fine.
I made a new organ recording today in the same church as before. Check out the attachments.... its probably the last for a while - they are fed up with me I think :-D
There are some modifications made since the last organ recording:
- New cable to the mics - dimension now allow it to come thru the holes made - better quality cable.
- New cable to the capsules - old factory ones almost fall of - quite poor soldering.
- Sealed the mic half with sikaflex - also sealed the cable entry so now a sealed cavity.
- Damping material inside mics
- Change the bipolar lyttics in the ADC for non-polar and now with higher voltage capacity.
- New rubber band suspension for the mics.
You can hear a short 24/44 excerpt by download the attachment.
Next occasion to use UGFR is at the swedish prince birthday and the 21 shot salute fired not long away from where I live. I have a bit of problem with this - I wonder how loud it is gonna get. And where to place the mics? How far and direction?
Here is the equipment for the salut: https://sv.wikipedia.org/wiki/57_mm_kanon_M/89
Here is the place: https://www.kungligaslotten.se/arti...slotten/2020-06-05-en-hogtidlig-halsning.html
Overview picture of site: https://www.kungahuset.se/images/18...0430_salut_Skeppsholmen_foto_H_Garlov_952.jpg
I used my SPL meter at todays recording - it showed 84 dBA during the last 3 second push - it can be heard in the end of flac download.
The statistics for that 3 sec part:
The recording you listen to has been amplified 5x6 dB = 30 dB. This is my headroom if I dont change the sensitivity strapping on the Comos ADC. It's now on the most sensitive, 1,7V. The mic is fed 5V. No gain in the mic. There is a setting for 6,7V - thats appr. 9 dB lower sensitivity. Perhaps that needed. Canons are loud...
Mic:
What say you?
//
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For a 1 dB noise floor increase, the equivalent acoustical noise of the ADC has to be at most 8 dB(A) SPL, for a 3 dB degradation 14 dB(A).
The dynamic range is about 127.8 dB(A) according to a review I read -> corresponding maximum level 135.8 dB SPL...141.8 dB SPL.
The sensitivity of the microphone is -37 dBV at 94 dB SPL, so
135.8 dB SPL -> 4.8 dBV, about 1.74 V
141.8 dB SPL -> 10.8 dBV, about 3.48 V
Somewhere in that range. Anything higher will lead to a substantial noise floor increase.
The dynamic range is about 127.8 dB(A) according to a review I read -> corresponding maximum level 135.8 dB SPL...141.8 dB SPL.
The sensitivity of the microphone is -37 dBV at 94 dB SPL, so
135.8 dB SPL -> 4.8 dBV, about 1.74 V
141.8 dB SPL -> 10.8 dBV, about 3.48 V
Somewhere in that range. Anything higher will lead to a substantial noise floor increase.
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Thanks!
OK, I'll notch it up to the 3,4V setting and need to back off - say 100 meters .. maybe I'm not allowed to come closer
Found here: https://curve.carleton.ca/system/fi...shotssoundanalysisidentificationandimpact.pdf
that a mortar is 160dB at 6 meter.
Using: https://www.wkcgroup.com/tools-room/inverse-square-law-sound-calculator/
gave:
Boom! :-D
Note to self - don't forget ear protection...
//
OK, I'll notch it up to the 3,4V setting and need to back off - say 100 meters .. maybe I'm not allowed to come closer
Found here: https://curve.carleton.ca/system/fi...shotssoundanalysisidentificationandimpact.pdf
that a mortar is 160dB at 6 meter.
Using: https://www.wkcgroup.com/tools-room/inverse-square-law-sound-calculator/
gave:
Boom! :-D
Note to self - don't forget ear protection...
//
Made L/R comparison measurement. Face to face config as below:
I think I will do a 1,2 dB gain adjustment as R ch is stronger on recording but no FR diff compensation. An absolute FR adjustment might be needed - have ta have access to a really reliable reference to do that.
y-axis spans 2 dB.
//
I think I will do a 1,2 dB gain adjustment as R ch is stronger on recording but no FR diff compensation. An absolute FR adjustment might be needed - have ta have access to a really reliable reference to do that.
y-axis spans 2 dB.
//
Attachments
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With the help form an other thread and member Juhazi, i now have the possibility for a much more portable system. I reused an old Android phone that was OK but screen started to look bad in the edges. Juhazi suggested an app, USB Audio Recorder PRO from eXtream, for recording over the phone USB interface and it seems to work great. I also bought an OTG converter cable - it all worked and record in 24/96.
This saves me 1,6 kg
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This saves me 1,6 kg
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Industry is catching up "32-bit float ultra-high-dynamic-range recording technology offers the ability to record signals exceeding 0 dBFS. There is in fact so much headroom that from a fidelity standpoint, it doesn’t matter where gains are set while recording. Audio levels in the 32-bit float WAV file can be adjusted up or down after recording with most major DAW software with no added noise or distortion."
https://audioxpress.com/news/zoom-unveils-uac-232-32-bit-float-usb-c-audio-interface
But higher levels than 0 dBFS... really .. isn't +0,1 dBFS per definition = clip?
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"32-bit float ultra-high-dynamic-range recording technology offers the ability to record signals exceeding 0 dBFS. There is in fact so much headroom that from a fidelity standpoint, it doesn’t matter where gains are set while recording. Audio levels in the 32-bit float WAV file can be adjusted up or down after recording with most major DAW software with no added noise or distortion."https://audioxpress.com/news/zoom-unveils-uac-232-32-bit-float-usb-c-audio-interface
But higher levels than 0 dBFS... really .. isn't +0,1 dBFS per definition = clip?
//
There is an analogue clipping level, see
https://zoomcorp.com/en/de/audio-interface/audio-interfaces/uac-232/#main
Maximum level XLR: +6 dBu TRS: +24 dBu / +11.5 dBu (when Hi-Z on)
Noise level max. -127 dBu A-weighted
Dual AD circuitry with 32-bit float recording technology
I think each channel gets digitized by two ADCs with different gain settings. At low levels, it automatically picks the ADC with high gain and at high levels, the one with low gain. That's a trick to handle the 133 dB(A) dynamic range of the microphone input without actually needing an ADC with 133 dB(A) dynamic range.
At the output, they put a digital circuit with an entirely useless volume knob that converts the signal into single-precision floating-point format.
https://zoomcorp.com/en/de/audio-interface/audio-interfaces/uac-232/#main
Maximum level XLR: +6 dBu TRS: +24 dBu / +11.5 dBu (when Hi-Z on)
Noise level max. -127 dBu A-weighted
Dual AD circuitry with 32-bit float recording technology
I think each channel gets digitized by two ADCs with different gain settings. At low levels, it automatically picks the ADC with high gain and at high levels, the one with low gain. That's a trick to handle the 133 dB(A) dynamic range of the microphone input without actually needing an ADC with 133 dB(A) dynamic range.
At the output, they put a digital circuit with an entirely useless volume knob that converts the signal into single-precision floating-point format.
Here is a more refined (and costly!) version of that idea: https://www.microtechgefell.de/mikrofonverstaerker?wl=1118-MV240digital
This one has been around for several years already.
It looks like Rode also embraced the same strategy in their new NT1 mk5:
They even go as far as calling it a world first
This one has been around for several years already.
It looks like Rode also embraced the same strategy in their new NT1 mk5: