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  1. #1 MONSTRO FAN 
    Senior Member Antony Newman's Avatar
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    In earlier Monstro sensor testing, SENSOR NOISE vs SENSOR TEMP was compared :

    +) The MONSTRO sensor has minimal noise AT or HOTTER than the Target Temperature that the sensor was Calibrated at.

    05 - 43 44 45 46 - 1024 pix

    +) Of the ADAPTIVE FAN algorithms currently on offer - 'ADAPTIVE' is the only option that is stable (the other options often have a mind of their own and should be avoided).

    +) The 'ADAPTIVE' algorithm 'wakes up' as it PASSES through a specific temperature.
    If your target temperature is 44 deg C -> this means that Calibration temperature will fluctuate AROUND 44 deg C.

    The problem with this:
    +) 1 deg BELOW Calibration (43c) - there is NOISE
    +) 1 deg ABOVE Calibration (45c) - there is NO Noise.

    To MINIMISE NOISE (for my sensor)
    +) Calibrate the sensor at 43,44 or (for Audio) 46 deg C - using 'Adaptive' Fan Mode
    +) Change the Target Temperature to 44,45 , or (For Audio) 47 deg <- ie 1 deg C hotter.

    AJ
    Last edited by Antony Newman; 11-01-2020 at 02:17 PM.
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  2. #2  
    Senior Member Antony Newman's Avatar
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    Even with the Monstro SENSOR CALIBRATED to 46 deg C - fan noise was AUDIBLE when the camera was NEAR the subject.

    +) In ADAPTIVE mode - a rapid ramp up to 30-40% would usually 'mess up' the sound.
    +) In MANUAL mode at 20% - the sensor slowly ramp up in temp introducing an unwanted time limit (before thermal runaway / unwanted image changes)

    Listing to the actual type of NOISE sound coming from the camera with the Fan set at 20-30%:
    +) The was a high pitched whistle / resonance (like a blade of grass under tension when blown over) - LOW LEVEL
    +) There was a super high pitch frequency that was BEAMING (ie as the microphone moves, it seemed to come in an out of focus) - LOW LEVEL
    +) There seems to be resonances sounds (ie stored energy) coming from the IN FRONT, TOP, RIGHT AND REVERSE sides of the camera - MID LEVEL
    +) There were electrical TRANSFORMER like sounds that came up through the FAN holes on the top, and through the EXHAUST ports. - MID LEVEL
    +) There is the sound of rushing air through the FANs on top - LOW LEVEL
    +) There was the sound of TURBULENT air coming from the EXHAUST vents - LOW LEVEL (but louder than the TOP FAN holes).

    00 - Monstro - Bare

    AJ
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  3. #3  
    Senior Member Antony Newman's Avatar
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    To investigate the root cause of the FAN NOISE, a few random attachments were created to to attach to FAN INTAKE holes - to SUCK the air away from the camera.

    +) CHIMNEY PIPE - Suck un air from LEFT of the Camera. Made from light weight foam.

    +) FLAT HOOD - Suck in air STRAIGHT BACK from the Camera. Made with a Heavy Duty Noise isolation material.

    +) SUPER CHARGER - Suck air un a streamlined shape (PTFE piping) encased in Heavy Duty Noise isolation material

    03 - Early Assortments

    AJ
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  4. #4  
    Senior Member Antony Newman's Avatar
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    Using a CALIBRATED MICROPHONE - I then tabulated a wide range of Audio DB levels at different FAN SPEEDS (20%-100%),
    using a variety of combinations of the above ATTACHMENTS, and a few more items to shape the stream of air IN and OUT of the Camera.

    04 - early numbers anal

    AJ
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  5. #5  
    Moderator Phil Holland's Avatar
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    Hello Anthony,

    I would investigate tonal response and DR in relationship to your findings because mostly what is going on is throwing the ISO rating out of whack and moving the black point and likely all the tones subsequently. I do believe what you think is "no noise" is actually lowering the black point.

    A valid and important test to do here is to look at a grayscale ramp and compare the patches both in noise character and measured value and consistency.

    To the tune of the fan noise when filming tight interiors a simple box atop with thin sound dampening panels and course air passthrough foam works a treat. I haven't had to use mine in about 2 years, but in a 6x6 room it snuffed out a bunch of sound. Pretty similar to your concept sans the tubing.

    Interestingly Komodo is alarmingly quite, so there's clearly been some evolution and R&D since DSMC2 was created on this front. Which really makes Komodo and future cameras exciting for live action sound applications.
    Phil Holland - Cinematographer - Los Angeles
    ________________________________
    phfx.com IMDB
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    2X RED Monstro 8K VV Bodies, 1X RED Komodo, and a lot of things to use with them.

    Data Sheets and Notes:
    Red Weapon/DSMC2
    Red Dragon
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  6. #6  
    Senior Member Antony Newman's Avatar
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    Thanks for the insight on hush boxes and suggest colour investigations Phil.

    +) In your own testing - did you reach an ideal temperature for your camera's sensor?

    +) Quiet Komodo : That's great news (I'll be joining the Komodo band wagon in 2021).

    AJ

    Quote Originally Posted by Phil Holland View Post
    Hello Anthony <snip> ..
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  7. #7  
    Senior Member Patrick Tresch's Avatar
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    Wondering where you are going but I'm really interested.
    I've also done a fan hood to prevent the noise of the fans to be heard. But it has to be really small not to prevent the air from flowing and so augmenting the fan noise.

    I still wonder why the engeneers decided :
    - to invert the heat flow from top to bottom of the camera?
    - to use 2 small fans instead of a bigger one?

    I callibrated my sensor to 48c.
    Unfortunately the callbiration temperature does determine the fan speed. If you want to have a different fanspeed tnan the cal map. You have to reset it manually at every startup.

    Pat
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  8. #8  
    Senior Member Antony Newman's Avatar
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    Hi Pat,

    As always you are always ahead of me!

    Here is the Hood that I created to help me understand the contribution of unwanted sound from RESONANCES through the top plate:

    01 - Monstro - Hood

    AJ

    Quote Originally Posted by Patrick Tresch View Post
    Wondering where you are going but I'm really interested. <snip>

    Pat
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  9. #9  
    Senior Member Antony Newman's Avatar
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    Pat,

    My guess is that majority of fan companies do not prioritize silence at low speed, and are only interested in air movement and pressure.

    Eg : The Blacknoise PM2 is a 40x40x20 mm fan vs the Delta Electronics AFB0412VHB-TP29 which is 40x40x15mm.

    +) Delta fan : Is 5mm thinner : 36.5dB max : Can move 11.7 m^3 / hr
    +) Blacknoise fan : 17.7dB Max : Can move 9.2 m^3 / hr

    The Blacknoise is almost inaudible at low speed - with a maximum sound level of 18.8 dB LOWER than the Delta at full speed.
    Just of 'fun' I bought 4 different Blacknoise fans. The amount of sound energy conducted through flimsy plastic was almost ZERO.

    Quote Originally Posted by Patrick Tresch View Post
    <snip> I still wonder why the engineers decided : <snip> - to use 2 small fans instead of a bigger one? <snip>
    Pat
    02 - Monstro - Hood - Fan

    AJ

    EDIT 1 : Clarification : I was suggesting that Red could consider upgrading the (Speculation) Delta fans with ones that are almost silent.
    The picture of the 'Chimney' attachment in Red is a larger single 80mm NB fan.

    EDIT 2 : The Delta Fan (which I speculate is in the Monstro) is actually 5mm thinner than the Blacknoise fan.
    Last edited by Antony Newman; 11-04-2020 at 06:43 PM.
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  10. #10  
    Senior Member Antony Newman's Avatar
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    Pat,

    When looking at the way the ADAPTIVE algorithm elects to play table tennis with the FAN SPEED - it looks like RED Very Rapidly slow the fan speed when the SENSOR is BELOW the TARGET TEMP. Conversely, when the SENSOR TEMP is the Same or Above the TARGET TEMP, they SLOWLY ramp up the fan speed.

    This 'avoiding' of the Sensor being below the TARGET TEMP would mirror descriptions of the MONSTRO preferring to be Hot than Cold.

    Unless I am mistaken - it is possible to set a TARGET TEMP for a calibration - and then MANUALLY set Fan speed throughout the calibration process (ie with a DIFFERENT SENSOR TEMP than the TARGET TEMP).
    In use, the BRAIN then aims for the TARGET TEMP that was set during calibration - allowing you to deliberately calibrate the Sensor for a temperature that is Just Below (say by 0.25 degrees C Below the TARGET TEMP).

    My strategy of getting the cleanest BlackShade is as follows:

    1) Choose a TARGET TEMP 'T' with the cleanest Min-Noise-at-high-ISO-test (ie non-sophisticated test)
    2) Use ADAPTIVE with TARGET TEMP = T for 15 mins -> Record Fan Speed
    3) Use ADAPTIVE with TARGET TEMP = T - 1 deg c for 15 mins -> Record Fan Speed
    4) Set ADAPTIVE TARGET TEMP to T
    5) Set MANUAL FAN speed (between (1) and (2)) to a point that Just causes the Sensor temp to dip into T-1 deg C
    6) Perform Calibration.

    This Calibration profile in ADAPTIVE will then ALMOST NEVER go below the actual SENSOR temp that the Calibration was performed.

    --

    In my cameras case, my (simple) noise test gave 43c and 44c as having minimum noise (at that temp and just above).
    I use a TARGET TEMP of 44c, and then manually set the Fan Speed during calibration that the SENSOR temp is approx 43.7 c.
    When recording in ADAPTIVE the camera does dip into '43c' - but only briefly, and likely not below 43.7c.

    As the Fan speed was set manually and a FIXED speed for the entire calibration (and I use a calibrated thermometer for the room to make sure the room has remained at exactly the same temp too) - My gut feeling is that this also creates a more 'perfect' black shade that when the Adaptive allows the Sensor temp to Drift during the calibration.

    AJ

    Edit : Also 46c calibration was my compromise temp (for audio) - as calibrations from 47c and above seem to loose colour details (density and hue).
    And 46c calibration still had a consistent set of results at 46-49c.


    Quote Originally Posted by Patrick Tresch View Post
    <snip>

    I calibrated my sensor to 48c.
    Unfortunately the calibration temperature does determine the fan speed. If you want to have a different fan speed than the cal map. You have to reset it manually at every startup.

    Pat
    Last edited by Antony Newman; 11-02-2020 at 09:05 AM.
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