Cooling fan(s)

10kDA

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Looking for recommendations for quietest cooling fans. I have a DSL40C and a 4203 that both run pretty warm and I want to add fans to both, and with as little impact on mic'ed recording as possible.

Thanks in advance for any recommendations.
 

mark123

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Noctua is what I use for computer builds. They're quieter. You can ramp them down with a PWM and you won't even hear them.

I had a fan in my 72 Super Bass and guarantee it's never audible.
 

PelliX

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The larger the fan, the less RPM you need for the same airflow, give or take. I run 120mm 12V fans on 9V, that keeps plenty of air moving to extract the heat from the combos and the noise is hardly noticeable. As for this interfering with recording... uhm... by the time you hear that fan, you're also hearing the inherent hiss of the amp and probably your own breathing if you're not a good few feet away. Really, that's a non-issue. Would almost be akin to saying you don't like the sound the tires make on a Harley...
 

JohnH

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DC fans with brushless motors and ball-bearings, running a few volts low can be very quiet. You have to find some DC supply though, without stressing existing low voltage supply in the amp.

I've had AC fans in my DSL combo for 15 years. I put two in series so each gets half the wall voltage. They are very effective and quiet enough, if I mic at a reasonable room volume, like a medium loud TV or more.
 

PelliX

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DC fans with brushless motors and ball-bearings, running a few volts low can be very quiet. You have to find some DC supply though, without stressing existing low voltage supply in the amp.

I've had AC fans in my DSL combo for 15 years. I put two in series so each gets half the wall voltage. They are very effective and quiet enough, if I mic at a reasonable room volume, like a medium loud TV or more.

I tend to snag 9V from the pedal power supply.
 

Gene Ballzz

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I tend to snag 9V from the pedal power supply.

That is a little less than convenient if your pedal board and it's power supply are 15 or so feet away from your amp, at say, your mic stand! It would be kinda neat if amp manufacturers would supply a 9 volt DC output on the amp, and for the industry to develop a standard for a fairly rock solid, durable and bullet proof system for getting that power to your pedal board.
Just Noticin'
Gene
 

junk notes

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heat sinks IDK, but are you going to have an intake/outtake or just go with a single low noise smart fan?
 

10kDA

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Thanks to all for replying. No pedals, so no convenient DC and I'm not inclined to make anything more complicated to add a DC supply.
Total silence is not required, just as quiet as possible, so noise floor is not asked to do too much.
Noctua is what I use for computer builds. They're quieter. You can ramp them down with a PWM and you won't even hear them.

I had a fan in my 72 Super Bass and guarantee it's never audible.
Thanks for the brand recommendation.What is a PWM?

I've had AC fans in my DSL combo for 15 years. I put two in series so each gets half the wall voltage. They are very effective and quiet enough, if I mic at a reasonable room volume, like a medium loud TV or more.
I like this idea of two fans at half voltage - yes, the amps will be recorded at +/- band rehearsal volume

heat sinks IDK, but are you going to have an intake/outtake or just go with a single low noise smart fan?
Just so I'm understanding correctly, by intake/outtake do you mean one fan blowing into the amp and another exhausting hot air? I'm not sure I need that as these are open back combos and a single fan would seem to disperse all over the place. But I could see the possible need for two fans blowing into the area of the chassis.
What do you mean by smart fan? Thermostatically controlled?

Thanks again.
 

JohnH

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hi @10kDA
Another thing I did, with my series pair of mains fans: When recording or getting a mic'ed PA feed, I put the mic on my extension speaker, so further from the fans in the combo.
 

junk notes

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Just so I'm understanding correctly, by intake/outtake do you mean one fan blowing into the amp and another exhausting hot air? I'm not sure I need that as these are open back combos and a single fan would seem to disperse all over the place. But I could see the possible need for two fans blowing into the area of the chassis.
What do you mean by smart fan? Thermostatically controlled?

Thanks again.
heat sinks IDK, but are you going to have an intake/outtake or just go with a single low noise smart fan?
yes, you are familiar? They seem to have plenty of electrical hook up and voltage options? IDK
cabinet cooling fan with thermostat control
 

PelliX

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I've generally gone with an 'extract only' mthod. The link posted above shows the fan blowing inwards, toward the valves, and while this is not bad per se, pulling the heat out seems better for a couple of reasons. One, you don't risk creating heat pockets in corners or whatnot. Two, when you shut the amp down you don't blow "cold" (ambient temp) air on on the valves, but rather keep pulling air indirectly. Obviously, if you tap the power off of the pilot light, then fan shuts down with the amp.

I like this idea of two fans at half voltage - yes, the amps will be recorded at +/- band rehearsal volume

At those volume levels, you'll have trouble hearing pretty much low voltage DC fan. Some of the larger AC extractor fans, like the ones often found on top of 19" racks can get noisy, though...
 

Jon Snell

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If you must have a fan, use a fan that sucks air out of the case/box/cabinet. That ensures an even cooling for the valves.
There are fans available that at full speed only produce 26db of noise which is quieter than most people whispering and even quieter at reduced voltage.
Two fans, one flowing cool air in and one flowing warm air out will only increase the noise levels.
More room in your studio is the ultimate answer, that will allow the warm air to dissipate naturally.
Try it and see what you think.
Good luck trying to appease your musicians
A thermal controller may help as you don't need a fan running a cold amplifier. The other way is to use the voltage produced by the ouput stage feeding your loudspeaker, rectify it and feed your fan with it. The fan will run at reasonable volume levels, when you need it and you won't hear a thing for the loudspeaker.
🤣
 

Vesperado

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For quiet operation I'd agree with those who are suggesting large DC fans on ext. supply. Try running a 24v fan at 12v, even more quiet, and expell the air from the PT/power tubes, do not blow on them.
 

JohnH

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More 'Factoids' about fans FYI:

The output of most fans is a fairly concentrated jet that punches through as a narrow stream. Good for cooling a particular hot area.
The flow into a fan is drawn smoothly from a much wider volume
Whether you blow in or suck out, the overall flow is probably the same
 

10kDA

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Thanks to everybody for your responses. I thinkI can proceed without making too much of a mess of things. LOL
 

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