Fair enough. In hindsight, looks like I jumped on you a bit there. Apologies.
For what it's worth, I do have an older QSC amp that has back-to-front cooling - a USA 850. Still works just fine, although I suspect the PSU caps are due for replacement.
Since I'm moving to front-to-back airflow, wouldn't the filters block the controls to the amps?
How did you work around that?
Chris
For what it's worth, I do have an older QSC amp that has back-to-front cooling - a USA 850. Still works just fine, although I suspect the PSU caps are due for replacement.
Since I'm moving to front-to-back airflow, wouldn't the filters block the controls to the amps?
How did you work around that?
Chris
Sorry disregard my suggestion. I mis-read your post and was thinking you were going all rear to front airflow.
I have not done enough installations with NU amps to bother paying attention to their airflow (usually only single-amp builds where it doesn't matter)
But have way too many experiences mixing Crown & Qsc in large racks and the issues that causes.
I have not done enough installations with NU amps to bother paying attention to their airflow (usually only single-amp builds where it doesn't matter)
But have way too many experiences mixing Crown & Qsc in large racks and the issues that causes.
I have heard that blowing air towards a hot object cools it more effectively than sucking air. I presume this is because blowing causes turbulence, which mixes the air at the air layer near the object.
Other than that, there could be thermal sensors somewhere on the board that only see fresh air when you reverse the fans.
Other than that, there could be thermal sensors somewhere on the board that only see fresh air when you reverse the fans.
Good to know that high pressure cools better than lower pressure. Any idea what sort of difference it makes? 1%, 10%, 50%..?
I could live with, say, 10%. The thermal capacity is there to drive 2ohm to clipping on all channels, and I'm going to have 8ohm loads most of the time. Occasionally 4ohm on a couple of channels.
Chris
I could live with, say, 10%. The thermal capacity is there to drive 2ohm to clipping on all channels, and I'm going to have 8ohm loads most of the time. Occasionally 4ohm on a couple of channels.
Chris
I'm sorry I do not have data on that. What I can find on the internet is mostly about CPU cooling, for which it appears there is not a large difference and that it depends on the heat sink geometry which direction works best.
Fan and heatsink - suck or blow? - Electrical Engineering Stack Exchange
Never mind.
Fan and heatsink - suck or blow? - Electrical Engineering Stack Exchange
Never mind.
My plan so far is a bit more crude:
- Switch amp on, let it sit for half an hour or so to get to thermal equilibrium.
- Connect worst-case load (on an NU6000, that'd be 4ohm on each side)
- Pink noise/sine tone/whatever, up to clip
- Time how long it takes to go thermal and shut down.
Open it up, reverse fan direction and repeat.
A data logger and some thermal probes would be a nicer way of doing it, for sure.
Weissi, I'd be worried about overloading the 24V supply with additional fans, but simply moving them to that side of the board might work. I guess the fans would need some kind of baffle, though, or they'll just short-circuit.
Chris
i was thinking of monitoring actual heatsink temps over time with all amps in a rack.
i asked my brother in law that works for a company doing HVAC and he couldn't tell me which airflow direction would be better but did state that on all the units the fans are mounted to exhaust air from the enclosure. amps are not hvac units and there could several reasons for the industry using that particular airflow direction that are not directly related to cooling such as introducing dirt and debris.
for your test are you planning a "dummy" load or actual speakers?
i would go with low frequency square waves as a test signal.
i asked my brother in law that works for a company doing HVAC and he couldn't tell me which airflow direction would be better but did state that on all the units the fans are mounted to exhaust air from the enclosure. amps are not hvac units and there could several reasons for the industry using that particular airflow direction that are not directly related to cooling such as introducing dirt and debris.
for your test are you planning a "dummy" load or actual speakers?
i would go with low frequency square waves as a test signal.
Someone has already tried reversing the fan and measured temperatures on a NU6000DSP: https://www.avsforum.com/forum/155-...01-inuke-nu6000dsp-fan-direction-results.html
The fan is not stock, it is a low noise one. The amplifier mosfets do not care about the direction, though a small component of the power supply prefers front-to-back.
The fan is not stock, it is a low noise one. The amplifier mosfets do not care about the direction, though a small component of the power supply prefers front-to-back.
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That's some great info!
Thanks for digging that out.
Once the new (front-to-back) amps arrive, I'll swap the Behringer amps so they're compatible.
Thanks again!
Chris
I thought about the reversed airflow in the inuke before I bought 3 nu4's ; they run so cool that when you mount them lower then the other (hotter?) amps, there will be no problem. Just make sure air can exit somewhere at the top of the rack and has air inlet at the bottom; as warm air rises.
I would not reverse the airflow as that has great impact on the airflow in the case.
Changing the fan for a quieter one is ok as long as you don't use it at full power.
I have way more knowledge from cooling then sound.
// if you use a fan to extract air from the rack (or any space); use minimal 2 same sized (passive) inlets (or 1 bigger) then the outtake for optimal flow/cooling.
I would not reverse the airflow as that has great impact on the airflow in the case.
Changing the fan for a quieter one is ok as long as you don't use it at full power.
I have way more knowledge from cooling then sound.
// if you use a fan to extract air from the rack (or any space); use minimal 2 same sized (passive) inlets (or 1 bigger) then the outtake for optimal flow/cooling.
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Depends on the application; cooling the case; yes. Cooling the chips in front of it; no - and that is their primary job.
Same reason you stand in front of a fan to cool down and not behind it; the airflow in front is directional and will cool a surface way better then air which is sucked from a location with least resistance, in this case about 2inches/5cm above the hot components.
Same reason you stand in front of a fan to cool down and not behind it; the airflow in front is directional and will cool a surface way better then air which is sucked from a location with least resistance, in this case about 2inches/5cm above the hot components.
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... Except some measurements showed a slight improvement of output device temperature by reversing the fan direction, and a PSU component that's normally out of the air flow got cooled much better by reversing the fans.
It's important that all the amps in a rack have the same direction air flow (either F2B or B2F). I have some Powersoft amps that are F2B, so I'll be swapping the fans in my NX4-6000 (which has similar internals to the NU4-6000) to match.
The airflow must all be in the same direction because having amps with different directions will result in cycling the same volume of air, getting hotter and hotter. That's not good for the amplifiers.
Chris
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