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Amps without cooling fan?

#82
Jeff Scott said:
The SWR SM400S does have a fan that blows across the heat sinks. It is just not externally visible except through the top slots of the amp. Even my old Bass 350 had a fan in it. SWR amps still got really hot, my guess being the fans were not effective enough.
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I should have been more specific. Although most SM400s amps have a cooling fan, MY SWR SM400s does not. The cooling fan was added fairly early in the manufacturing cycle of the "S" iteration of the amp, but mine was made prior to the additional of the fan. As such, finding one without a fan is going to be difficult at best, rendering my suggestion invalid. The 400s was a slightly more powerful iteration of the SM400, which did not have a cooling fan; that said, I should have noted the SM400 is an amp without a cooling fan.

SWR was very clear relative to rack mounting both the SM400 and SM400s amps. The manufacturer specifically stated that although the amp fits in two rack spaces, they recommended at least three to allow proper cooling. When the company discovered too many buyers were not reading the instructions, they added the cooling fan. I always had mine properly mounted in the rack with unobstructed top vents in the rear. I understand a number of people complained about thermal shutdown in these amps, but I used mine nightly for 15 years and never had a thermal shutdown. In fact, the only issue I ever had was the tube in the pre amp needed to be replaced. Others may have had a different experience; this is merely my experience.

My apologies for not being more specific initially.
 
#83
Manticore said:
I should have been more specific. Although most SM400s amps have a cooling fan, MY SWR SM400s does not. The cooling fan was added fairly early in the manufacturing cycle of the "S" iteration of the amp, but mine was made prior to the additional of the fan. As such, finding one without a fan is going to be difficult at best, rendering my suggestion invalid. The 400s was a slightly more powerful iteration of the SM400, which did not have a cooling fan; that said, I should have noted the SM400 is an amp without a cooling fan.

SWR was very clear relative to rack mounting both the SM400 and SM400s amps. The manufacturer specifically stated that although the amp fits in two rack spaces, they recommended at least three to allow proper cooling. When the company discovered too many buyers were not reading the instructions, they added the cooling fan. I always had mine properly mounted in the rack with unobstructed top vents in the rear. I understand a number of people complained about thermal shutdown in these amps, but I used mine nightly for 15 years and never had a thermal shutdown. In fact, the only issue I ever had was the tube in the pre amp needed to be replaced. Others may have had a different experience; this is merely my experience.

My apologies for not being more specific initially.
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I didnt know that the early "no fan" SM400 was unreliable. Ive read and experienced the opposite. As long as they were rack mounted properly as described by @Manticore they are known to be bullet proof. I know mine is and it's pretty old now. Brian Beller claims his tumbled down a starcase. Mine fell of a stack onto concrete. One flange got bent out of shape and a faceplate screw popped but it still lives. I run mine bi-amped, bridged and otherwise aggravated sometimes and the worst that has ever happened is burnt fingers. To be fair, after that happened, I installed a fan for my sake (but that was after something like 20 years of service).
 
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#84
Roxbororob said:
I didnt know that the early "no fan" SM400 was unreliable. Ive read and experienced the opposite. As long as they were rack mounted properly as described by @Manticore they are known to be bullet proof. I know mine is and it's pretty old now. Brian Beller claims his tumbled down a starcase. Mine fell of a stack onto concrete. One flange got bent out of shape and a faceplate screw popped but it still lives. I run mine bi-amped, bridged and otherwise aggravated sometimes and the worst that has ever happened is burnt fingers. To be fair, after that happened, I installed a fan for my sake (but that was after something like 20 years of service).
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I believe the fan was added out of an abundance of caution due to complaints from those that couldn't be bothered with instructions.

I also owned the 17th Red Head made. It did not have a fan and it too was ultra-reliable. The Red Head didn't have quite enough grunt for my purposes (thus it was always run flat-out), so I picked up an SM400s when they became available and ran it at 4 ohms. I know quite a number of folks that used these amps without any problems at all; I've only read about others having issues with them. I'll stand by my recommendation of the SM400 as an ultra-reliable amp without a fan; this is, however, based upon my personal experience. Not everyone likes the pre amp voicing, but even that is easy enough to work around.
 
#85
agedhorse said:
The enclosures have shrunk to where there is inadequate convection, especially when driving very hard.
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I would say that this thread could be a good market survey for the fashion of producing increasingly (cheaper and less durable?) compact and lightweight amplifiers that led to the use of cooling fans. Manufacturers should clearly state if their compact amplifiers feature forced ventilation. Or should I say, in this online-shopping-days we’re living, if manufactures indicated the durability of the cooling fans they installed in their amps or the sound pressure level they generate, would customers not go for a more reliable (and old fashion) solution cooled by natural convection, even having to sacrifice compactness?
Combos (unlike bass heads) provide a good opportunity to use fanless amps since they have more space to accommodate heat-sink fins. Additionally, combo amps can be installed vertically at the back of the speaker improving natural convection – the air flow caused by the speaker movement can be directed to the fins – and the fins can be hidden inside the cabinet so that finger burns can be avoided…:unsure:
 
#86
Manticore said:
I should have been more specific. Although most SM400s amps have a cooling fan, MY SWR SM400s does not. The cooling fan was added fairly early in the manufacturing cycle of the "S" iteration of the amp, but mine was made prior to the additional of the fan. As such, finding one without a fan is going to be difficult at best, rendering my suggestion invalid. The 400s was a slightly more powerful iteration of the SM400, which did not have a cooling fan; that said, I should have noted the SM400 is an amp without a cooling fan.

SWR was very clear relative to rack mounting both the SM400 and SM400s amps. The manufacturer specifically stated that although the amp fits in two rack spaces, they recommended at least three to allow proper cooling. When the company discovered too many buyers were not reading the instructions, they added the cooling fan. I always had mine properly mounted in the rack with unobstructed top vents in the rear. I understand a number of people complained about thermal shutdown in these amps, but I used mine nightly for 15 years and never had a thermal shutdown. In fact, the only issue I ever had was the tube in the pre amp needed to be replaced. Others may have had a different experience; this is merely my experience.

My apologies for not being more specific initially.
Click to expand...
Thanks for that info. I have owned and used quite a few different SWR amps over the years. I have always wondered when one of them would fail from overheating as they (SWR) got really hot compared to other non-fan cooled solidstate amps I have owned/used (Gallien-Krueger and Walter Woods primarily, but others, too). Even with amps that had built-n fans I always hung a Rotron fan onto them to blow cool air into the chassis.
 
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#87
The use of cooling fans have nothing to do with being cheaper (actually they are more expensive), but to improve performance and power levels in smaller, lighter enclosures that are being demanded by many players.
 
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#88
agedhorse said:
The use of cooling fans have nothing to do with being cheaper (actually they are more expensive), but to improve performance and power levels in smaller, lighter enclosures that are being demanded by many players.
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Largely because of the need for actual enclosue space to move the fan's air? Plus maybe variable speed circuitry on some? Just curious.
 
#89
As cases become smaller and component density becomes higher, the watts per cubic inch that needs to be dissipated grows to the point that forced airflow is necessary.

The thermal models resemble electrical circuits with sources, resistance, capacitance and inductance. Thermal, pneumatic, hydraulic and electronic share many of the same equations, just the variables are called different things.
 
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#94
ricardol said:
I would say that this thread could be a good market survey for the fashion of producing increasingly (cheaper and less durable?) compact and lightweight amplifiers that led to the use of cooling fans. Manufacturers should clearly state if their compact amplifiers feature forced ventilation. Or should I say, in this online-shopping-days we’re living, if manufactures indicated the durability of the cooling fans they installed in their amps or the sound pressure level they generate, would customers not go for a more reliable (and old fashion) solution cooled by natural convection, even having to sacrifice compactness?
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No.
I would and did buy an amp based on knowledge of a company's continued commitment to extreme reliability and refusing to just make something to just sell and not care if it worked 5 years later or not. As you said it is easy to get opinions online, they will tell you the fan noise and service failures, just check around. Even on this Thread some have given you their experience of a few amps that have fans that you can not hear.

I will re post my earlier post on this Thread.

S-Bigbottom said:
Not with the Mesa Subway D800 and the Genzler Magellan 800. They are so quiet that the only way you get fan sound is if you put your ear on the opposite hole and get the wind going directly in your ear canal.
Another advantage to not having the external heat sink but a fan is that when you turn the amp off you can pack it up right away and not get burned. The Genzler's body does not get much more than room temperature.
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Those are two amps that do not have anything but durable parts in them.

It is weird quoting oneself. :cool:
 
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