Why fans? Why not proper passive cooling?

[Thurbs]

The simple answer is price.

- Heat syncs cost more.
- Quiet fans cost more.
- Designing in temperature controlled fans costs more.
- Components which have a larger temperature range cost more.
- and so on...

If quietness is your goal then go valve. Oh, but then you want it small and light?

Compromise is the name of the game.

[eddiehoffmann]

At this rate bass players are gonna take the post form keyboard players as the biggest geeks in the music world...

[Musicman20]

The Genz amps have the quietest fans out of all the amps I've owned. The loudest fan was a big old Trace 400GP12SMX.

In fact, the Streamliner is probably the quietest amp ive heard with a fan.

[paul_5]

I had an Ampeg B2re once that had a REALLY LOUD FAN (yes, I know I'm shouting, I'm trying to be heard above the din ).

[Rich]

[quote name='stingrayPete1977' timestamp='1344780735' post='1769019']
One of things I like about my Genz 3.0 is the lack of fan, never gets hot either. The 6.0 is a bit annoying for quiet practice with its whir.
[/quote]
The 6.0 has got a fan in it?? Blimey I don't think I've ever heard mine.
My SWR SM-900 used to get so hot I swear I could have fried an egg on it.

[3below]

[quote name='LiamPodmore' timestamp='1344780561' post='1769016']
Depending on the fan size, seeing as most of them use PC fans anyway, would it not be easier for companies to use silent/low noise fans in the first place?

Liam
[/quote]

Agree, when I had peavey firebass 700 I replaced fans with low noise computer types. Was pretty cheap £12 or so. So that's £6 per fan, Which means they cost UK firm £3 each, which means £1.50 to make at a guess. So £6 on a £4 ~ 500 amp. They could of course use thermistor or some such temperature fan speed control. Cost of a thermistor - pence.

Why the need for fans? Physics I am afraid. Only so much thermal energy removed by passive cooling in rack / micro head format. Forced convection much more efficient.

Edited August 12, 2012 by 3below

[umph]

[quote name='Musicman20' timestamp='1344768410' post='1768844']
I think the new Tecamp Puma 900 uses the chassis to disburse of excess heat. No fan! Cool idea.
[/quote]

pun?

[JTUK]

[quote name='warwickhunt' timestamp='1344770220' post='1768867']
The Thunderfunk has a switch-able fan (generally for studio use) and in fact even with the fan off at a gig, the amp can dissipate the heat without the need for a fan so long as you aren't cranking it/going daft.
[/quote]

I've cranked it with the fan off...which as you know you can hardly hear anyway so not entirely to blame and the amp ran VERY hot..as hot as my SWR which has heat sinks only, and it did fine.
I wouldn't want to do it often, but this testifies to the sheer quality of the components and build of both, IMO... to run that hot and not miss a beat...

I don't think many make amps like these anymore... sheer quality.

[warwickhunt]

[quote name='JTUK' timestamp='1344842298' post='1769829']
I've cranked it with the fan off...which as you know you can hardly hear anyway so not entirely to blame and the amp ran VERY hot..as hot as my SWR which has heat sinks only, and it did fine.
I wouldn't want to do it often, but this testifies to the sheer quality of the components and build of both, IMO... to run that hot and not miss a beat...

I don't think many make amps like these anymore... sheer quality.
[/quote][quote name='JTUK' timestamp='1344842298' post='1769829']
I've cranked it with the fan off...which as you know you can hardly hear anyway so not entirely to blame and the amp ran VERY hot..as hot as my SWR which has heat sinks only, and it did fine.
I wouldn't want to do it often, but this testifies to the sheer quality of the components and build of both, IMO... to run that hot and not miss a beat...

I don't think many make amps like these anymore... sheer quality.
[/quote]

I was packing away after a gig when I had a sudden thought that I might have switched the fan off when I'd been doing some acoustic/home rehearsals several weeks before; checked the switch and sure enough it had been off for at least a couple of gigs. I hadn't been driving it mega hard (still a 5 piece rock covers band playing pubs and not using the PA to support backline) and it didn't seem to be 'that' hot at the end of the gig, certainly not enough to worry me!

[VTypeV4]

The fan on my Ashton is rather loud which can be a little distracting in a quiet environment. I expect I could unplug it if needed as there's vents above the power valves and both front and rear.

As for passive cooling, a block of solid aluminium which acts as a heat sink will probably cost more than a cheap fan made in their millions in china or wherever.

[gillento]

[quote name='Musicman20' timestamp='1344795558' post='1769243']

In fact, the Streamliner is probably the quietest amp ive heard with a fan.
[/quote]

+1

[Mr. Foxen]

[quote name='VTypeV4' timestamp='1344855457' post='1770041']
The fan on my Ashton is rather loud which can be a little distracting in a quiet environment. I expect I could unplug it if needed as there's vents above the power valves and both front and rear.
[/quote]

Not figured why that has a fan, it doesn't run the valves hot or packed silly close together.

[Dood]

[quote name='3below' timestamp='1344810699' post='1769596']


Why the need for fans? Physics I am afraid. Only so much thermal energy removed by passive cooling in rack / micro head format. Forced convection much more efficient.
[/quote]

This. I feel sure that people will realise how important the fan is when it is not there! Small amplifier IC's are pretty small really and can get super hot very quickly. A heatsink bolted to it is only half the story. Passive cooling relies on getting the heat away from the components as quickly as possible. Something that is very difficult should the amplifier be inside a rack case with no throughput of air. An electric fan can create that movement of air necessary to take the heat away from the heatsink and thus cool the components.

[Bill Fitzmaurice]

[quote name='warwickhunt' timestamp='1344844620' post='1769851']
it didn't seem to be 'that' hot at the end of the gig, certainly not enough to worry me!
[/quote]Not worrysome perhaps, but that's not the purpose of a fan. Passive sinking keeps component temperatures down to a given differential above ambient. Fans can keep that differential smaller. The cooler components run the longer they last. And if you can hear the fan over your playing you're not playing loud enough.

[PlungerModerno]

[quote name='Bill Fitzmaurice' timestamp='1344864474' post='1770256']
Not worrysome perhaps, but that's not the purpose of a fan. Passive sinking keeps component temperatures down to a given differential above ambient. Fans can keep that differential smaller. The cooler components run the longer they last. And if you can hear the fan over your playing you're not playing loud enough.
[/quote]

This^^^^

For a piece of studio equipment a very quiet variable speed fan might be an option, along with heatsinking.

For a 500W + amp? variable speed that's not extremely loud will probably do just fine. How low are you going to be playing. For a practice combo a loud fan would (haha) blow

[bremen]

I just learned something about airyplanes from that!


'Winglets at the blade tip decrease the
tip vortex which occurs as air spills off the tip from the high to the low pressure side of the blade'

http://airlineworld.wordpress.com/2008/10/01/aircraft-winglets/

[Phil Starr]

The problem is that class AB amps produce a fair bit of waste heat and heat causes breakdown of transistors. I used to build amps and a 200W amp needed a 150x100mm heatsink with finned fins to dissipate the heat anything beyond this was pretty difficult to dissipate efficiently. As bass amps have become more powerful passive heatsinking becomes impractical.

Class D is more efficient and so produces less waste heat. Combine this with a switch mode power supply and the heat produced inside the amp is much lower. The designer of the Peavey IPR 1600 claims his amp will run without a fan [url="http://www.avsforum.com/t/1150665/peavey-ipr-class-d-amps/420"]http://www.avsforum.com/t/1150665/peavey-ipr-class-d-amps/420[/url] but it is included because the public wouldn't have confidence in the amp without a fan. If he is right we may see a return to passive heatsinking.

Perhaps you should use a 100W amp or less for practice at home.

[VTypeV4]

[quote name='Mr. Foxen' timestamp='1344863259' post='1770229']
Not figured why that has a fan, it doesn't run the valves hot or packed silly close together.
[/quote]

Thats what I thought although I have seen versions with the fan mounted vertically blowing/sucking(?) at the valves in a Trace Elliot V-Type kinda way..

[Mr. Foxen]

[quote name='bremen' timestamp='1344867554' post='1770326']
I just learned something about airyplanes from that!


'Winglets at the blade tip decrease the
tip vortex which occurs as air spills off the tip from the high to the low pressure side of the blade'

[url="http://airlineworld.wordpress.com/2008/10/01/aircraft-winglets/"]http://airlineworld....craft-winglets/[/url]
[/quote]

The fans in amps and pcs are in a ring so count as ducted fans.

[Bill Fitzmaurice]

[quote name='VTypeV4' timestamp='1344893326' post='1770874']
Thats what I thought although I have seen versions with the fan mounted vertically blowing/sucking(?) at the valves in a Trace Elliot V-Type kinda way..
[/quote]Where valves are concerned keeping them cool isn't of any benefit, keeping the heat they create out of the other components is.

[grandad]

I also share this dislike of fans in my bass amps & therefore my current rigs, (Peavey & Roland), have none. My PA though, (Yamaha EMX), does, & I don't mind that as it is barely audible. I suspect it's because the bass amps with fans that I've owned have not been quiet enough when used at home for practice & that means in a small room where the fan's hiss presents a distraction when concentrating. On stage it wasn't noticable.

It is not beyond the capability of manufacturers to build in quiet, reliable, thermostatically controlled fans & some do e.g. my HP laptop currently being typed on. Studio use of course demands quiet equipment.

In my previous working life I have encountered radio transmitter valves of the kilowatt variety, (2-3 feet tall), being cooled by large volumes of blown air. Also, water cooled rectifier diodes plumbed into a water jacket & supplying 100's of amps to industrial D.C. motors. Supercooled, refridgerated amplifiers are used at the front end of satellite receivers to maintain a high signal to noise ratio. So, whether to avoid thermal overload and/or to maintain a low noise threshold cooling ain't new. It's production costs I suspect that dictate, but noisy fans lacking any control are just not accepable & there's no excuse for manufacturer's not to address the problem.

Edited August 14, 2012 by grandad

[largo]

My tinitus blocks out any fan noise if I'm playing that quietly

[Jack]

The fan in my GK is annoying, has anyone replaced the fan in the MB Fusion?

[PlungerModerno]

[quote name='Jack' timestamp='1344934817' post='1771177']
The fan in my GK is annoying, has anyone replaced the fan in the MB Fusion?
[/quote]

Interesting idea... Is it really REALLY loud?

I'd wait till the warranty period was over till I modded one - but I guess lots of cooling air is the price of 3 full voltage preamp tubes.
Sucks that the fan is noisy though. Maybe the only answer is to turn it up!

[Jack]

It's not really loud at all but the amp is also my home practice amp if I'm not using headphones.

I'm a computing enthusiast and I'm currently 2 feet away from a huge metal box with 3 140mm fans, 2 120mm fans and a 180mm fan. Id guess the GK was easily twice as loud, and at a much more annoying frequency (likely because of the amp's fan's smaller diameter).