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  #121  
Old 05-04-2021, 12:25 PM
martthie_08 martthie_08 is offline
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Default Re: Need a new quieter fan to HD IO..

Quote:
Is it the 4 pin NF-A8 PWM? If so did you just use two wires to connect it?
yes, I just connected ground and +12V

Quote:
That version seems to be similar specs to the silenx fan people have used.
yes, that's why I chose it,
if Silenx had been available I would have gotten that one, based on the good reviews that one gets.
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  #122  
Old 05-30-2021, 06:13 AM
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Suad Cokljat Suad Cokljat is offline
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Default Re: Need a new quieter fan to HD IO..

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Originally Posted by skylab001 View Post
I just swapped the fan in one of my 192's because the original one had started clicking and I was worried about imminent failure. I used a Noctua NF-R8 redux 1800
How did you manage to install PWM fan in 192 DC fan environment?! PWM fans require constant voltage input and PWM signal to adjust fan speed. Almost all PWM fans will spin at 100% if no PWM signal is present. 192 and HD I/O output variabile DC voltage for fan, meaning a standard DC fans (3 pin) must be used, with signal pin not connected. From Noctua portfolio NF-A8 FLX is the proper fan type to be used with 192 and HD I/O.

HD I/O and 192 use internal temperature sensor (or sensors) to control fan DC voltage (max 12V). Because 192 does not use sensor signal from fan (usually yellow wire) and it does not know what is the exact fan RPM, the issue here when replacing the stock fan with 3rd party models is threshold voltage and percentage decrease. These are precisely adjusted for the stock fan and can have unpredictable results with other fan models (for example - under 7V some fans will not start).

So, almost every attempt to silence 192 or HD I/O by replacing stock fan with even best 3rd party fan with less RPM and CFM will result in less airflow inside the device housing and more heat for PCBs and components.

My point - all these posts back from 10 years ago until today and people just blindly replacing stock fan with Silenx or any other "quiet" fans are focusing on fan noise but not on cooling efficiency! 192 internally runs very hot, especially analog input and output cards. Even with the noisy stock fan, some components on I/O cards run so hot that after few hours of operation you can almost burn your finger on it!

To properly enhance 192 or HD I/O thermal design (cooling) and make it quieter but keep same or make even better cooling efficiency, several factors need to be considered:

1. How exactly 192 thermal design works
2. What is the exact airflow from air intake to fan exhaust
3. Which components generate the most heat
4. Which components are most sensitive to overheating
5. What can be done mechanically to enhance the airflow within casing
6. Keeping all mentioned in mind - how much fan RPM can be reduced and keep the similar cooling efficiency

All this is not an easy task and requires some precise measurements and lot of testing. I have a spare 192 and I will play with it and try to find a proper quiet cooling solution.

For now I just replaced 192 stock fan with Noctua NF-A8 FLX and can confirm 192 internally becomes hotter because of less airflow. Although with Noctua 192 is now quite silent and can be placed in control room.


BTW, is there anyone who 10 years ago installed slow RPM fan into full rack of expanded 192s and can confirm all is still running OK???

Best regards,

Suad
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  #123  
Old 07-12-2021, 03:47 AM
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Default Re: Need a new quieter fan to HD IO..

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Originally Posted by skylab001 View Post
I can feel that the Noctua doesn't push as much air as the Cofan when I put it side by side with my other 192's, yet on another thread somebody posted that Digi had said the stock fan was 34 CFM? Maybe they changed specs?
I did some more testing:

All quiet low RPM fans will push less air resulting in less airflow inside 192 and overheating (especially AD card). To increase fan RPM you should add 12K resistor across R22 or across pins 1 and 3 of U6. This will add around 2V offset to original voltage-temperature graph and make low RPM fan spin faster. Digi 192 with stock fan when turned ON goes to 11.3V (max) and then drops to around 4.5V (min) which is not enough for some low RPM fans to even start.

Even better than adding resistor is to replace stock R22 thermistor with thermistor of lower value around 4,7K. Depending on fan used you can try 4,7K and 6,8K (Stock NTC is around 10K). This will make low RPM fan (tested with Noctua A8 FLX) start around 7.0V and go to around 9.5V after few hours of use when 192 gets hot. This is perfect ratio of fan noise and cooling performance, and much quieter than stock fan solution.

Cheers!

Suad
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  #124  
Old 07-12-2021, 03:51 AM
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Default Re: Need a new quieter fan to HD IO..

Every time you say "all" you are wrong. Fans are mass produced for a cent per thousand units so there is room for improvement. Obviously the buyer (DigiDesign/Avid) has only requested certain spec for airflow, but not for noise levels. With better bearing and more clever blades you can get more airflow with less noise, but the beancounters want to get manufacturing cost down.

You could also question why the fan is needed at all. You could install liquid cooling system that is completely noiseless. But beancounters would not like, because it adds to manufacturing costs.
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  #125  
Old 07-12-2021, 04:04 AM
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Suad Cokljat Suad Cokljat is offline
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Default Re: Need a new quieter fan to HD IO..

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Originally Posted by JFreak View Post
Every time you say "all" you are wrong. Fans are mass produced for a cent per thousand units so there is room for improvement. Obviously the buyer (DigiDesign/Avid) has only requested certain spec for airflow, but not for noise levels. With better bearing and more clever blades you can get more airflow with less noise, but the beancounters want to get manufacturing cost down.

You could also question why the fan is needed at all. You could install liquid cooling system that is completely noiseless. But beancounters would not like, because it adds to manufacturing costs.
I think you missed my point. I think Digidesign did the best they could to cool down 192. Stock Cofan fan is good performance and reasonably quiet fan. Digi 192 runs very hot and needs good cooling especially when expanded and installed in closed rack. Even with stock fan 192 gets internally very hot.

What I want to point here is - if someone just swap stock fan with low RPM fan - cooling will be much less efficient and 192 will internally get very very hot, especially AD card. After replacing the stock fan some other components also must be adjusted/replaced to adapt and to adjust airflow to new voltage-RPM ratio.

Cheers!

S
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  #126  
Old 07-12-2021, 04:06 AM
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Default Re: Need a new quieter fan to HD IO..

Got it. Have noticed 192's with additional AD card are hotter than others
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  #127  
Old 10-05-2021, 12:58 PM
electrobumps electrobumps is offline
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Default Re: Need a new quieter fan to HD IO..

Quote:
Originally Posted by Suad Cokljat View Post
I did some more testing:

All quiet low RPM fans will push less air resulting in less airflow inside 192 and overheating (especially AD card). To increase fan RPM you should add 12K resistor across R22 or across pins 1 and 3 of U6. This will add around 2V offset to original voltage-temperature graph and make low RPM fan spin faster. Digi 192 with stock fan when turned ON goes to 11.3V (max) and then drops to around 4.5V (min) which is not enough for some low RPM fans to even start.

Even better than adding resistor is to replace stock R22 thermistor with thermistor of lower value around 4,7K. Depending on fan used you can try 4,7K and 6,8K (Stock NTC is around 10K). This will make low RPM fan (tested with Noctua A8 FLX) start around 7.0V and go to around 9.5V after few hours of use when 192 gets hot. This is perfect ratio of fan noise and cooling performance, and much quieter than stock fan solution.

Cheers!

Suad
Thanks for all the information on the voltage levels. Great knowledge on the 192. Is the temperature sensor(s) in the 192/HD i/o? As the data sheet states the fan is available with a temperature sensor? I always thought they ran at constant speed apart from when you turn it on. I've never noticed a change in fan speed after startup.

The stock fan specs are 2400 RPM 34.33CFM as per the data sheet. However as what is the RPM and CFM at 7.0v and 9.0v. Are they linear?

Data sheet - https://cofan-usa.com/pdf/dc_8025i.pdf
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  #128  
Old 10-09-2021, 03:45 AM
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Default Re: Need a new quieter fan to HD IO..

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Originally Posted by electrobumps View Post
Thanks for all the information on the voltage levels. Great knowledge on the 192. Is the temperature sensor(s) in the 192/HD i/o? As the data sheet states the fan is available with a temperature sensor? I always thought they ran at constant speed apart from when you turn it on. I've never noticed a change in fan speed after startup.

The stock fan specs are 2400 RPM 34.33CFM as per the data sheet. However as what is the RPM and CFM at 7.0v and 9.0v. Are they linear?

Data sheet - https://cofan-usa.com/pdf/dc_8025i.pdf
Stock fan datasheet specifies temp sensor as an optional feature. However, 192 uses the very basic version of the fan with only GND and +12V wires. 192 has only one temperature sensor and it's located inside 192 on the mainboard (under PSU, near front panel connector). Fan speed controller (U6) adjusts output voltage based on thermistor resistance reading. Higher the temperature within 192 casing, thermistor resistance will drop and fan voltage (and RPM) will go up. 192 does not use RPM signal from the fan, so fan speed and voltage is determined only by thermistor resistance value.

Stock thermistor is around 10K value (maybe 12K, I don't remember). I found 4.7K thermistor ideal for Noctua low RPM fans (such as A8 FLX). The reason to change thermistor is - with stock thermistor, low RPM fans will run too slow and in some cases they wont even start at lowest setting when 192 is powered on (after initial max speed fan burst Noctua fan slows down and stops).

When 192 is turned on, fan controller first kicks to max (around 11.4V) and then slows down to around 4.5V. After that, voltage will slowly rise as temperature inside goes up. With stock fan I measured around 7V after few hours of operation at normal room temperature. 7V is enough for the stock fan to maintain good airflow but it's insufficient to most low RPM fans (it will be very quiet but 192 will overheat)

The whole point is - to make 192 significantly quieter by using modern quiet low RPM fan, but keep airflow and cooling performance as close (or better) to stock. During operation 192 becomes internally very hot, especially AD cards.

Cheers!

S
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  #129  
Old 10-09-2021, 07:18 AM
martthie_08 martthie_08 is offline
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Default Re: Need a new quieter fan to HD IO..

this is some great information, thanks for posting!
would you happen to know if this translates to the next generation of AVID HD I/O interfaces?
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  #130  
Old 10-09-2021, 07:42 AM
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Suad Cokljat Suad Cokljat is offline
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Default Re: Need a new quieter fan to HD IO..

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Originally Posted by martthie_08 View Post
this is some great information, thanks for posting!
would you happen to know if this translates to the next generation of AVID HD I/O interfaces?
Almost certainly yes. If you send detailed pictures of HD I/O mainboard, especially area where fan connector is located, I could tell you exactly where thermistor and controler are located and what to measure. As I remember that part of HD I/O is very different than 192.

I don't know if HD I/O overheats similar as 192. I see AD and DA cards use different converter ICs. On 192 greatest source of heat are AD converter ICs and then DA ICs. Heat is dissipated over thick copper traces on inner layers of PCB to copper hearsinks making great thermal stress to nearby SMT capacitors. Heatsinks are then cooled down by airflow sucked by fan from air intake next to IO cards. That's why AD card installed to expansion slot runs even hotter.
I see HD I/O analog cards doesn't have heatsinks. That suggest less heat produced by ICs as I doubt AVID would remove heatsinks just to decrease costs. At the other side big source of heat is PSU, especially mosfets and parts on large heatsink on secondary side.

So bottomline - by carefully combinig low RPM fan and thermistor, HD I/O could run even more silent (less RPM) than 192 with great colling performance.

Cheers!

S
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