how important in the fan in mark series amps?

[JimAnsell]

particularly a mark IV that is in a 4 space rack case, or a short head.
i'm just wondering, because the fan in my rack kit is pretty loud, so it makes it annoying when i play at lower volumes.
i can unplug it at quiet volume, but thats a pain in the ***.
if i take it out, will it make a big difference?
is overheating, or anything actually a risk with these?

 

[chris_EIT]

well I have another amp without a fan and them tubes get mighty hot! In a rack i'd say you want the least heat you can get dude, as for it being annoying at low volumes. well your volume must be REALLY low cause i never really hear it OVER the amps loudness

 

[straitouttahell]

as for it being annoying at low volumes. well your volume must be REALLY low

Or the ball bearing on his fan has arrived to the end of its days

 

[Jeff R]

On my III, the fan plugs into a dedicated AC outlet on the bottom-side of the chassis. I've unplugged mine temporarily for recording and didn't experience any problems. But logic tells me the fan is probably there for a good reason, and I should normally use it even if I don't know exactly why it's there.

 

[ramalam]

The fan in very important. I wouldn't let the amp run more than 15 minutes or so with the fan unplugged. I hear that you can use 220 volt fans in the fan socket and get much quieter results without any problems and that type of fan is very inexpensive.

 

[carlosasi]

I suppose it might be more important in a head but in my combo IIA for example when Mike B at Mesa refurbed it we discussed the fan and he didn't think it made a huge difference in normal playing intervals. So I have 4 glowing 6l6's burning away with no problems. Mind you I can't even hear the fan in my Mark III once things get cranking.

 

[dodger916]

The fan in my Mark IV combo is barely noticeable. Tha fan in my rackmounted Mark IIC+ is like a turbine!

 

[MesieBooga]

Anyone have a source for those old Howard fans?

 

[phyrexia]

my III doesn't even have a fan.

My D180 will burn itself up though without the fan. Of course I would imagine that 6 6L6s would run kinda hot.

 

[6L6C]

The fan in very important. I wouldn't let the amp run more than 15 minutes or so with the fan unplugged. I hear that you can use 220 volt fans in the fan socket and get much quieter results without any problems and that type of fan is very inexpensive.

The 220 is a good idea just to have some sort of air flow. I use to have a .22 and also a subway rocket both amps had (2) EL84’s putting the tubes aside; the chassis use to get real hot! And you still have a fair amount of components above that. Kind of like throwing the components in a frying pan.

A Mark IV short head I would have a fan back there, allot of stuff in the chassis in a cramp space. I find my fan in a Mark IV med head noisy but not bearing related it’s just all the air it’s moving its most likely overkill, think I will pick up a 220.

 

[JD]

I had noisy fans on my simul sat and mark3 ( the one on my mark 3 got to the point that it would not not start it would just hum unless I gave it a kick start) thats how I noticed the fan wasn't working while I was playing I could smell a burning smell I got really worried shut off the amp and found it was the tubes because the fan wasn't working so in my experience I wont play my amps without the fan running and I play in an Air con room. Any way the way I fixed them was I removed the fan blade by taking out 3 screws cleaned and re oiled the bushes now they are both whisper quiet and start every time.

 

[Boogiebabies]

Anyone have a source for those old Howard fans?

They pop up on ebay once in a while. Mostly from old server racks. When they are sold as Boogie fans they go for more money. Mesa has replaced the Howard Industries fans with Globe Motors fans. They are an exact replacement in size.

The old Howard fans do not have bearings. They are electro-magetic and ride on a shaft. They fan is held to the drive shaft with a c-clip. When they get noisy, I coat the inside with dielectric grease and use a synthetic lube for the shaft and fan blade housing contact surface. They will run ultra quiet for about two years or more before the rubbing noise comes back and the friction throws the blades out of balance.

 

[Boogiebabies]

particularly a mark IV that is in a 4 space rack case, or a short head.
i'm just wondering, because the fan in my rack kit is pretty loud, so it makes it annoying when i play at lower volumes.
i can unplug it at quiet volume, but thats a pain in the ***.
if i take it out, will it make a big difference?
is overheating, or anything actually a risk with these?

The only reason I would prefer to run a fan is that the MK IV does not have the classic Boogie heat sink. On the flip side, in heads or rackmounts, fans really do not move much air. The intake area is small and it basically draws warm are due to the smaller compartment and the proximity of the fan to the power tubes. In combos, there is no restriction on the air draw and the air is actually cool, but it really only benefits the far right and middle tubes due to the placement. The far left tube usually runs much warmer. I have had many time where, in a combo, I could touch the three tubes with no problem, but that first tube was hot enough to burn the old fingers. Obviously, in a head/rack the warm air does not cool the tubes down very much, but the hanging tubes dissipate the heat up to the chassis. It's more of a chassis cooler than a tube cooler in these cases. I would use one. If you can find a fan with a lower RPM or CFM rating it will run quieter. For you guys with an older MK series with a leaf blower motor, these amps dissipate nicely with the heat sink. In the meantime, you can pull the fan apart and lube it.

 

[phyrexia]

I had noisy fans on my simul sat and mark3 ( the one on my mark 3 got to the point that it would not not start it would just hum unless I gave it a kick start) thats how I noticed the fan wasn't working while I was playing I could smell a burning smell I got really worried shut off the amp and found it was the tubes because the fan wasn't working so in my experience I wont play my amps without the fan running and I play in an Air con room. Any way the way I fixed them was I removed the fan blade by taking out 3 screws cleaned and re oiled the bushes now they are both whisper quiet and start every time.

Are you sure the burning smell wasn't the motor of the fan binding?

 

[JD]

No it was definately just the tubes getting hot I took the fan out straight away and there was no smell with the fan.

 

[ANIMATED SUSPENSION]

Because the MKIV head is essentially the combo without a speaker i.e the tubes are hanging 'upside down' underneath the chassis it needs a fan to stop heat build up causing reliability problems. Heat rises and obviously no vent on top of the amp, so cool air is sucked in from under the head and the warmed air is dissipated out the back. My Single Rec has only 2 power tubes which are on top of the chassis, a vent at the front and back so doesn't need a fan.

 

[igfraso]

My Mark I head (8/77 and signed by RCS) has no fan and I was just wondering if I should add one to it.
Regards

 

[Nomad]

Yes the fan is a good thing. It wont hurt your amp short term to run it without the fan though over time without the fan things inside will begin to get brittle way faster than they would without the fan.

With all those tubes crammed into such a small area in either a head or combo there can be a good bit of heat build up over a couple hours playing time wether your playing a 75 watt, 85 watt, or 100 watt amp.

The 60 watters generally dont have them becuase there isnt quite as much heat but I'd have one in mine if it were.

IMO any amp with EL84 tube sockets soldered to a PC board should have a fan in it wether two or four tubes. If the sockets are chasisi mounted and not soldered to a board then there is no worry.

If I owned an origonal Mark I that didnt have a fan I'm not sure if I woul put one in it unless Mesa did it. The value of the amp I would think would go down if it was modded (even to have a fan). Now if it could be donr in a manner that looked totally origonal it might not matter.