Quiet Fans?

[wizard333]

Anyone found a particularly quiet fan, AC or DC, that can be mounted in an amp to blow on the tubes (especially those EL84 space heaters) and keep them cool?

[Enzo]

Get out your catalogs and pay attention to the noise figures included in the specs for many if not most. SOme are even intended as lower noise fans with names like whisper fan. SOme lower noise by reducing airflow, so don't ignore that spec either.

[pdf64]

Regular 12Vdv pc type fans, whether small ones intended for mounting on the processor heatsink or larger ones for the case, run very quietly when operated from ~9V of rectified / smoothed heaters and can make a big impact on heat build up.
Pete

[Steve Conner]

The Etri 126LJ claims a noise level of 22dBA. I used one in a high powered hi-fi amp, mounted on rubber shock mounts, and it was pretty quiet. I managed to slow it down even more by connecting a capacitor in series, shorted out by a thermal switch if the heatsink got too hot.

The 126LH claims to be quieter still, 10dBA.

I'm sure other reputable makers like Papst would have fans with an equally low noise level.

[Leo_Gnardo]

Here's a quiet one recommended over at Audio Asylum:

http://www.amazon.com/Antec-TrueQuie...m-Cooling/dp/B

Here's the AA thread:

cooling find - Bill Way - Tubes Asylum

Looks like a hit to me - hope it works for you.

[km6xz]

One sure way to make the fan noise go away is an 11 or 12 on the master volume control...

Fan noise is made up of a couple components including the air path turbulence, fan blade turbulence, bearing noise, all of which increase with higher air velocity. More volume at less speed can reduce two of those noises. For example slowing down two fans to get the same volume will be quieter if all else is the same.
You can also try a better heat transfer system such as boxing the tubes in a wind tunnel that requires less volume while increases air flow in contact with the envelopes. Much of heat from tubes is radiated instead of conducted from the glass. Some tubes do not depend on radiation but direct contact for heat dissipation, either by fluid flow(oil, distilled water or cooling fluid) or by exterior anodes with fins positioned in the flow of a high volume blower directing all air through the tube fins.
There used to be tube coolers, fined black heatsinks you could slide over individual tubes. The black absorbs radiant heat and the fins are more efficient radiators in air flow than clear glass. The ones designed for 12AX7s would fit on EL84.

I built a large power amp for hi-fi for a manufacturer which used two small tubes with exterior anodes and fitted the entire power amp section including driver tubes inside a clear pyrex column filled with clear transformer oil. The tubes, about 1/2 the size of a 6550 were rated for 300w plate dissipation each. Using a standard off the self 275 watt Hammond transform it loafed at 300 watts and the convection current inside the column keep the tubes cool. I built one for a bass player also. The hi-fi company was selling them for $45,000/pr. Cool looking but not worth anything close to that. Some variation on that theme could be used for cool running eL34 or EL84 using a low volume cooling fluid pump and radiator like some of the higher end graphics cards use. Keep them cool, and isolated from vibration and tubes last a lot longer.