Quiet internal fans

[Alistair]

I just received an old Perreaux amplifier I mentioned in another thread, and the cooling fan is dead. I'd be keen to replace it just to make sure it doesn't overheat, but I'm a bit concerned about the volume.
I found a nice drop in replacement at jaycar (120x120mm, 240v operation etc), but it's rated at 44dB, which seems like it will be loud enough to be annoying.

Anyone have any better leads on internal fans? The quick reading I've done suggests 240v fans are always a bit loud.

[mylesgm]

if you get 12v fans you can always drop the voltage and therefore the speed by using a voltage divider. I've done this before and it works well when you just want to keep the air moving and silent.

[otto ruiter]

Are you sure the fan runs at full speed when it turns on? If not it'll be quieter than the spec.

If you can post the original maker/model, we can compare the replacements for:
depth (probably 25mm or 38mm)
current requirement
air flow rate (cu ft/min or cu metres/hour or litres/sec)
noise in dB
bearing type (ball or bush)
lead connections

You really want to achieve the same flow rate as the original. Anything more will be wasted and give higher noise.

here's an example...
http://au.element14.com/multicomp/mcdp203a-2123lbl-gn/fan-120x120x38mm-230vac/dp/1568427

[lonearranger]

in terms of PC type fans - these guys have a lot to choose from
http://www.pccasegear.com/index.php?mai ... Path=9_510

They are 12v though. Is there a 12v source from the amp powersupply?, or you could power via wall wart.

[Alistair]

Thanks guys-

It's a Kondo Electronics Japan, Model EP114H-38
118mmx118mm (but 120mm seems to be standard and that will fit easily)
38mm depth
240 v, 50/60hz, 24/22 watts axial flow fan
Soldered connections

Unsure about the rest of the info sorry. I haven't been able to find the manufacturer or specs online.

Unfortunately I don't have a schem for the amp so I'm not sure what voltages are available in the amp. Would rather get a drop in replacement if I can, but if it's not possible I can rig something up for 12v.

[otto ruiter]

Not a maker that seems to be well known. Most of the fans that draw that sort of current (24W = 100mA) seem to push a fair bit of air (80 to 100 cu ft/min) and are reasonably noisy (47dB or so). I'd go with a fan from Jaycar, even the 25mm unit http://www.jaycar.com.au/productView.asp?ID=YX2516&keywords=fan&form=KEYWORD might be a good choice if you can fit it. If it turns out too noisy then worry about a quieter replacement.

[Hookemeister]

Hi Alistair

WES Components has a 120x120x38mm ball bearing fan that will deliver 85 cfm at a noise level of 43db.

WES code for it is FAN201B, $15.50 if you have an account with them. Delivery $6,90 overnight.

Greg

[Alistair]

Thanks for the links guys. Yeah, that one at Jaycar is the first one I found. Unfortunately I don't have a WES account, but I found the specs online, and that looks the best of the 240v fans I've found. 43db just seems way too loud for studio use though. I think dropping it down to 12v might be the way to go- there are a million 12v computer fans that would fit the bill and still provide the same amount of air.

[Hookemeister]

Hi Alistair

I can't really see how the 12 volt fans would be any quieter than the 240 volt type as the noise level is going to be a function of fan speed (rpm), the pitch of the blade and the amount of cubic air it's moving. As both fans have to move the same amount of cubic air and they are both the same size, then the only variables that remain are the speed and pitch of blade.

As far using a 12 volt fan with a voltage divider... that's tempting fate... unless there is a thermal feedback control circuit to adjust the speed of the fan... now it's getting complicated.

I'd be locating the amp in another room... that solves all your problems and it'll free up a bit of rack space.

Greg

[Alistair]

Well, I replaced the fan with the Jaycar type just to get it up and running- 47dB is loud!
It's running very cold with this fan, so I think I could probably run a lower powered fan without too many dramas. A machine room would be ideal, but unfortunately it's not really possible in my current location.

Good news is that the amp is otherwise running perfectly, and sounds fantastic. Considering it's age and appearance (and the amount of filth inside it) I wasn't it expecting it to be great, but it's great. Heaps of detail but not harsh at all.