Help with ac line interference due to cooling fan install

[Lovemystereo]

My tube amps are installed in a cabinet and run hot after a while operating. Not an option to have outside the cabinet. To solve this after some research I purchased and installed a 120mm 115 volt ac (direct plug in fan – see link below). Recommendation I read was to go with AC rather than low voltage DC (wall wart plug in type) to minimize interference. There were a number of control options, such as variable speed. Taking the automatic hands off approach I opted for a unit with a thermal switch incorporated (On at 85 degrees, Off at 75 degrees). It works to cool, though louder than I would like.

The problem: when the fan operates there is a loud clicking sound from the speakers. This is ac line interference, I am certain. Not come across this issue before. When fan is NOT operating, everything is great, but the moment the fan starts, so does the noise, making the fan unusable as a cooling device due to the interference.

Here is link to the fan I installed- https://www.productsforautomation.com/gardtec-gcab702-120mm-120V-cooling-fan-kit-p/gcab702.htm

Any ideas on solutions appreciated? Seems like in trying to solve one problem, I have created another! Hopefully there is some kind of ac filtration or something I can install between the fan’s plug and the rest of the system to shield/filter out the noise? Or some other way to resolve?? The main amp is plugged directly into the wall, while all the other components including the fan are plugged into a UPS incorporating surge protection.

Thank you in advance for your assistance.

 

[Oerets]

A power conditioner maybe for the amplifiers?
Or a 1/1 isolation transformer/AC outlet.

 

[David_NC]

I've always used DC fans for cooling my audio equipment. I like to use the larger ones that are around 5" or so. Instead of running them on their specified 12 volts, I typically use a 9 volt adapter so they'll run slower (and quieter), though I have one that's powered by a 5 volt iPad adapter. I've never had any interference from these fans whatsoever. I'd think that most decent AC adapters would work for this. If you have an old PC cooling fan - from a power supply, case, or CPU heatsink, it'd be an easy way to test this.

 

[peterh]

My tube amps are installed in a cabinet and run hot after a while operating. Not an option to have outside the cabinet. To solve this after some research I purchased and installed a 120mm 115 volt ac (direct plug in fan – see link below). Recommendation I read was to go with AC rather than low voltage DC (wall wart plug in type) to minimize interference. There were a number of control options, such as variable speed. Taking the automatic hands off approach I opted for a unit with a thermal switch incorporated (On at 85 degrees, Off at 75 degrees). It works to cool, though louder than I would like.

The problem: when the fan operates there is a loud clicking sound from the speakers. This is ac line interference, I am certain. Not come across this issue before. When fan is NOT operating, everything is great, but the moment the fan starts, so does the noise, making the fan unusable as a cooling device due to the interference.

Here is link to the fan I installed- https://www.productsforautomation.com/gardtec-gcab702-120mm-120V-cooling-fan-kit-p/gcab702.htm

Any ideas on solutions appreciated? Seems like in trying to solve one problem, I have created another! Hopefully there is some kind of ac filtration or something I can install between the fan’s plug and the rest of the system to shield/filter out the noise? Or some other way to resolve?? The main amp is plugged directly into the wall, while all the other components including the fan are plugged into a UPS incorporating surge protection.

Thank you in advance for your assistance.

Use a continuously running fan.
The use of a thermostat mounted in the fan might allow hotspots to occur that the sensor does not react too.
AC fan has less dependencys as no powersupply is involved. Whatever you use install a separate
security sensor that breaks power from the whole cabinet if temperature rises above some value, this
is to prevent your home from burning down.

 

[Lovemystereo]

Thankyou for your input everyone. Just want to reiterate, the problem I have is with the noise coming from the speakers caused by the fan when spinning. The fan does cool the cabinet and turns off when the preamp has cooled. The problem is with the impact of the fan once it switches on to cool. It creates a load clicking sound from the speakers (interference) while operating. Only when it stops spinning does the clicking sound stop. All signal lines (RCS cables) are a distance from the power supply chords. The clicking sound from the speakers occurs when any souce (CD, Tuner, etc.) is operating, or even when nothing is playing. The sound is caused by inference to the amplifier by the fan. Is there a way to remove it that is cost effective. Fan was about $30. Should I give up on it?

 

[peterh]

Thankyou for your input everyone. Just want to reiterate, the problem I have is with the noise coming from the speakers caused by the fan when spinning. The fan does cool the cabinet and turns off when the preamp has cooled. The problem is with the impact of the fan once it switches on to cool. It creates a load clicking sound from the speakers (interference) while operating. Only when it stops spinning does the clicking sound stop. All signal lines (RCS cables) are a distance from the power supply chords. The clicking sound from the speakers occurs when any souce (CD, Tuner, etc.) is operating, or even when nothing is playing. The sound is caused by inference to the amplifier by the fan. Is there a way to remove it that is cost effective. Fan was about $30. Should I give up on it?

Get a new fan without thermostat. pabst for instance, but make sure you can stand
the noise it emits while blowing.Also figure out a way to monitor tempereture and shut all off if
to hot. But have the fan(s) running all the time the amps are active.

 

[Lovemystereo]

Peterh, do you think the thermostat switch is the cause of the interference, or is it the fan itself, t.stat switch or not? Thank you.

 

[peterh]

Peterh, do you think the thermostat switch is the cause of the interference, or is it the fan itself, t.stat switch or not? Thank you.

If it makes "noise" wneh the fan is running there is a problem. A AC fan has no elements that can
make noise it's only a coil creating a magnet field.
A thermostat might "click" each time it opens or closes". And you should not use a on/off regulation,
the amps produces a fairly constant heat, and it should be ventilated fairly constant.
Get a new fan, a cheap AC fan , or even better a few fans with different acustic noise level
and choose the one you can stand

 

[petehall347]

make sure fan wire is not parallel to other wires .

 

[Lovemystereo]

Peterh: I think I am making some headway. Just got off the phone with another fan supplier and after sharing my dilemma, they suspect the problem may indeed be the thermostat causing the "click" interference. Would you mind taking look at the link below that shows what may be the thermostat(??) as a small bump in the green power supply wire of the kit I now have installed.
https://www.productsforautomation.com/gardtec-gcab702-120mm-120V-cooling-fan-kit-p/gcab702.htm

Had assumed this was some kind of line filter and the sensor was in the fan case itself, but it may be in the green wire as the person from the other manufacturer thought, but acknowledges he is just guessing. Anyway let me know your thoughts. Thinking I may experiment by building my own power supply cable for the fan (without the bump thing) to see if the clicking still occurs.
Thoughts?

 

[Lavane]

I've always used DC fans for cooling my audio equipment. I like to use the larger ones that are around 5" or so. Instead of running them on their specified 12 volts, I typically use a 9 volt adapter so they'll run slower (and quieter), though I have one that's powered by a 5 volt iPad adapter. I've never had any interference from these fans whatsoever. I'd think that most decent AC adapters would work for this. If you have an old PC cooling fan - from a power supply, case, or CPU heatsink, it'd be an easy way to test this.

I've always preferred DC fans. Many of the fans used for computer towers run on 5 or 12 volt. All 3 fans in my computer tower are 5 volt whisper fans.

 

[analogadict]

Peterh: I think I am making some headway. Just got off the phone with another fan supplier and after sharing my dilemma, they suspect the problem may indeed be the thermostat causing the "click" interference.
Thoughts?

That was my suspicion too after reading the first post. Most of my turntables have ac motors and they require a "spark suppressor" across the internal switch that turns on the motor. You need a X1 rated cap or snubber across the thermostat or relay that is switching the motor.

Regards,

Anwesh

 

[peterh]

Peterh: I think I am making some headway. Just got off the phone with another fan supplier and after sharing my dilemma, they suspect the problem may indeed be the thermostat causing the "click" interference. Would you mind taking look at the link below that shows what may be the thermostat(??) as a small bump in the green power supply wire of the kit I now have installed.
https://www.productsforautomation.com/gardtec-gcab702-120mm-120V-cooling-fan-kit-p/gcab702.htm

Had assumed this was some kind of line filter and the sensor was in the fan case itself, but it may be in the green wire as the person from the other manufacturer thought, but acknowledges he is just guessing. Anyway let me know your thoughts. Thinking I may experiment by building my own power supply cable for the fan (without the bump thing) to see if the clicking still occurs.
Thoughts?

Yes by all means disconnect the thermostat. You could cut the original wire around the T and splice it
together. In my opinion you should not have a thermostat in this application the fan(s) should
operate continuously.

 

[maxhifi]

IMHO you're best off using a solid state amp than an improperly ventilated tube amp. The fans are a band-aid, and will likely not cool the entire cabinet evenly unless a lot of attention is paid to convection and airflow. I also think it is an unnecessary fire hazard. Tubes are great and all but I'd way rather run solid state than risk a house fire.

That said, I agree that if you insist to do it this way, the fans should run continuously, and should be AC powered. Running continuously is also less obnoxious because a constant background noise is better than hearing the fans cycle on and off. I suspect the one you got is simply not suitable for use near audio gear. It should also not be located too close to the input tubes or other sensitive areas of the amplifier. I agree with Peterh's idea to use a thermal interlock which shuts down the whole cabinet if it detects high temperature.

But really, putting tube amps into this sort of environment reminds me of people living in a bachelor apartment and no yard with a large dog. My feeling is that it is probably more trouble than it is worth to use tubes in this sort of application, and you'd be far better off with a quality solid state amp.