Amps without fans

BartmanPDX · #1 04-17-2011, 12:16 PM

The recent "look at all the nasty crap that built up in this old amp" thread got me thinking about amps and fans and how fans are mechanical and thus potentially more subject to breakdown. That got me wondering how many really good bass amps there are out there without fans. I can't think of many. I know my Berg IP310 has a 1000w power amp and no fan, but most of the bass heads I can think of have fans.

So, how many bass amps are there without fans? I'm not looking to buy anything, I'm just curious . . .

will33 · #2 04-17-2011, 12:19 PM

GK's 800rb, SWR's workingman series (older ones anyway) and a lot of tube amps, lower power ones at least. That's about all I can think of right now.

FWIW, the SWR's run way hot and often need a little fan sitting on the back of the cab blowing on the heatsink. The 800rb runs cool pretty much no matter what.

shoot-r · #3 04-17-2011, 12:22 PM

IMHO, there shouldn't be any without a fan.

Heat is a bass amps worst enemy.

I bought a brand new GK 800 head in 1984.
From day one I've had a cheap, 4", Radio Shack fan blowin' on the back cooling fins.
I credit that fan to my GK's 27 years of problem free service.

BartmanPDX · #4 04-17-2011, 12:25 PM

Totally forgot about the GKs. I had a 400RB that served me problem free for almost 20 years. Duh. It never died, and I never used a fan.

seamonkey · #5 04-17-2011, 12:27 PM

No enough. Fans have got to go. I have got to think the majority of amp "failures" are no failures of electronics but failures of the cooling causing overheating and protection circuits kicking in.

The powered speakers can get away with it because they use heatsinks and Vertical panels that promote a chimney effect of hot air rising and cooler air pulled up from below. Convection.

Nobody is going to want a vertical form factor bass amp. If it just hung off the side the cab it would be good enough. But in this market full of tradition and familiar looks it would be really pushing it to change the form factor.

BartmanPDX · #6 04-17-2011, 12:30 PM

Quote:

Originally Posted by seamonkey

No enough. Fans have got to go. I have got to think the majority of amp "failures" are no failures of electronics but failures of the cooling causing overheating and protection circuits kicking in.

The powered speakers can get away with it because they use heatsinks and Vertical panels that promote a chimney effect of hot air rising and cooler air pulled up from below. Convection.

Nobody is going to want a vertical form factor bass amp. If it just hung off the side the cab it would be good enough. But in this market full of tradition and familiar looks it would be really pushing it to change the form factor.

Interesting. I had asked the question because I have some powered qsc monitors with no fans that perform flawlessly and seem quite robust (don't get hot). But the vertical form factor no doubt is a huge part of it.

BartmanPDX · #7 04-17-2011, 12:33 PM

With all the talk now of doing vertical 210s, it would be neat to build a vertical 210 combo with the cooling fins for the amp running up the back. It would be tough to make them rugged enough to withstand road wear though.

Passinwind · #8 04-17-2011, 12:37 PM

Quote:

Originally Posted by BartmanPDX

Totally forgot about the GKs. I had a 400RB that served me problem free for almost 20 years. Duh. It never died, and I never used a fan.

I despise fans and amps without 'em are far more likely to pry my wallet out of my pocket. Acoustic Image is at the center of my radar screen right now mainly because of this.

BartmanPDX · #9 04-17-2011, 12:43 PM

Quote:

Originally Posted by Passinwind

I despise fans and amps without 'em are far more likely to pry my wallet out of my pocket. Acoustic Image is at the center of my radar screen right now mainly because of this.

I hear you, Charlie. A fan would seem to be one of the most likely points of failure (thus leading to heat problems). Any amp that can do without one would seem to be potentially more durable.

Passinwind · #10 04-17-2011, 12:47 PM

Quote:

Originally Posted by BartmanPDX

I hear you, Charlie. A fan would seem to be one of the most likely points of failure (thus leading to heat problems). Any amp that can do without one would seem to be potentially more durable.

Yep, but heat sinks are big, expensive, and weigh a lot. My big PA amps all use fans, and I never really hear 'em. Whatever bass amp I own has to sound great soloed in my living room, or on jazz gigs where there are patrons 5 feet or so away from the rig. A lot of times the fan noise still gets lost, but it really bugs me the times when it doesn't.

The variable/switched ones are fine in my book as long as the amp will still carry on if the fan fails.

shoot-r · #11 04-17-2011, 01:00 PM

Quote:

Originally Posted by Passinwind

A lot of times the fan noise still gets lost, but it really bugs me the times when it doesn't.

+1...

This is why I've been happy with my "add a fan" to my old GK 800 head.
Over the years when the head has been used at recording work and there's been some fan noise bleed through I can simply unplug the power to the fan.
In a live band setting I've never heard the fan running and the head stays cool to the touch.
I know the GK 800 was designed to not need a fan, but I like the little extra dependability insurance it provides.

BartmanPDX · #12 04-17-2011, 01:20 PM

Quote:

Originally Posted by Passinwind

Yep, but heat sinks are big, expensive, and weigh a lot. My big PA amps all use fans, and I never really hear 'em. Whatever bass amp I own has to sound great soloed in my living room, or on jazz gigs where there are patrons 5 feet or so away from the rig. A lot of times the fan noise still gets lost, but it really bugs me the times when it doesn't.

The variable/switched ones are fine in my book as long as the amp will still carry on if the fan fails.

For me, it's not a noise issue. I've rarely heard most of the fans on my amps, though my shuttle is getting noisier recently. It's still not a problem. Then again, I play rock mostly. Nothing wrong with adding fans. I just don't want to be in a situation where a fan dies, and I don't notice it, and my amp gets fried as a result of excessive heat buildup.

But the heavy heat sink requirement is the big downside to fan-less designs.

JimmyM · #13 04-17-2011, 01:24 PM

i have had several tube amps without fans and they have never overheated once. but seamonkey's right...a fan malfunction was at the root of the problems i used to have with my swr solid state amp. and the 400rb had overheating problems for a while until they got it figured out. i knew quite a few people who had this problem with the 400rb in the late 80's and early 90's. i once saw one turn into an anchor right before my very eyes.

so much for the theory that tube amps are an inferior design, eh seamonkey?

steveksux · #14 04-17-2011, 01:56 PM

Quote:

Originally Posted by Passinwind

I despise fans and amps without 'em are far more likely to pry my wallet out of my pocket. Acoustic Image is at the center of my radar screen right now mainly because of this.

Quote:

Originally Posted by BartmanPDX

I hear you, Charlie. A fan would seem to be one of the most likely points of failure (thus leading to heat problems). Any amp that can do without one would seem to be potentially more durable.

Quote:

Originally Posted by shoot-r

+1...

This is why I've been happy with my "add a fan" to my old GK 800 head.
Over the years when the head has been used at recording work and there's been some fan noise bleed through I can simply unplug the power to the fan.
In a live band setting I've never heard the fan running and the head stays cool to the touch.
I know the GK 800 was designed to not need a fan, but I like the little extra dependability insurance it provides.

Sounds like amps without fans DO have fans after all, 3 fans in this thread alone.

Pre/power setups fair game? I had a K1 power amp, an early digital model with no fan, 1500 watts bridged at 4 ohms. Recently replaced it with the new crown xls 1500 series.

Regarding fans vs more heat sinks vs hotter components vs lifespans, it's all really relative. More or less the same temp can be achieved with larger heatsink, no fan, or smaller heatsink with a fan. Its all a balancing act, you try to optimize some combination of temp/weight. Use a good fan you might get more life out of the components and no worries about the fan. Use a cheap fan and it may be a weak spot in the design. Use no fan, skimp on the heat sink and risk higher temps, the components may fail before a fan would have.

No hard fast rules, its all in the engineering and the safety factors you chose as you make all these design compromises regarding weight, temp control, costs.

Randy