Educating Myself About Fan Noise

It's very rare for an audiophile amplifier to have a fan. They use large heat sinks to avoid the fan noise. I only know of Hafler amps using a fan. Pro amps do too but that's all.

I believe my Mosecode 600 had a fan. I never heard it unless I was right in front of it. My HD sat.box has a fan--same thing---Altho at avs.com many complained of the fan noise from this very box--- as well as fan noise from dpl rear proj.tvs. and projectors. The first 2 projectors I owned were NOISY as hell. My 3rd wasn't,even tho it had a fan.So I guess it's 'how' this fan thing is implimented,along with which fan is chosen.

Thanks, already I am glad I finally asked this question. I think this Dynaco model has an interesting history and I like owning it (audio equipment becomes a hobby and a learning experience after all) but now I can see a little that other options won't necessarily run into this fan noise problem.

As I think about it, I think I read a review a few years ago of a Nakamichi item that had a fan that bothered the reviewer a bit.

Hi everyone

Apologies for hi-jacking/reviving this old thread but I'm in need of some fan noise education/help myself.

I've got a vintage Sumo 9+ amp that has been restored by Gas Audio/Sumo specialist Mike Bettinger. He gave the amp the works, new power caps, new ceramic caps, re-biasing, new input/output jacks, extensive break-in. I got the Sumo back recently and the music sounds great. The only downside is the rear fan that is used in the Sumo 9 Plus is very audible (greater than 30 db) when I'm listening to acoustic music or quieter passages of songs. It didn't bother Mike but it bothers me.

I sit about 9 to 11 ft away from the Sumo 9 Plus when I'm listening to music. I've tried putting it as far away as I could from me but I still hear the fan. Now one thing that did help was an extra sheet of sound absorbing material from Acoustipack (Sound proofing for PCs and servers). I draped the sheet over the rear of the amp and the fan just leaving some space though for air to escape from the sides. The noise went down by a little bit but still not enough.

Now I'm going to try to find a quieter replacement fan that still pushes enough air out to keep the Sumo operating a safe temp but should I not find a suitable replacement I had an idea.

I don't know if many of you remember the wood cabinets that were used to encase Phase Linear amps. It was a box that was an exact fit to the amp but had an open back. I was thinking about doing something similar. I would be encasing the Sumo in a wood cabinet with a bit of space on the sides, top and rear but leaving the back only partially open to allow for some air to escape as well as routing of power cord, ICs and speaker wire. Within the cabinet I would put acoustic dampening foam or carpet padding to muffle the sound.

Now I'm definitely open to suggestions as to how to combat the fan noise. The enclosure sounds like overkill and can be a bit costly depending on the quality of the box as well as sound proofing material. Plus I may have muffled the fan noise but now may be harming the Sumo with excessive heat. Also I'm hoping the acoutic material doesn't start emitting toxic fumes because of the heat.

Now if anyone has any fan suggestions for the Sumo 9+ I'm open to those as well. I'd like to get the quietest fan that can still push a decent amount of air. I was thinking about Yate Loon fans or maybe Nexus fans but I know there are tons out there in the market.

Well thanks so much everyone.

Can you put some rubber grommets between the fan housing and whatever it connects to?