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I have an old wood entertainment center that I'm using for my system. I have about 1.25" of clearance over the tubes in my VT60 and I put a piece of aluminum on the bottom of the shelf above it, offset with a couple of washers, to disperse some heat. I want to build a tube phono stage and might be able to squeeze it next to my Meridian on the top shelf. There's a version within an enclosure and another with open tubes on top(which I like a little better). The front has a wooden sliding door like a rolltop desk and once it is pushed up and open, that would only leave me about 3/4" above the open tubes up to the sliding door. Should I worry about the heat? I assume the phono tubes will put out much less heat than my 6550 tubes do. If the ventilation or burn potential is too great, I'll have to mount some kind of shelf off to the side to hold the phono preamp. The two wood panels are hinged to the top which lifts up and the turntable is inside. Just curious if anyone else is using their tube gear in smaller enclosed spaces.
Follow Ups:
Hi ,
With regards to ARC equipment, the owners manual recommends ( for full function tube preamps , phono stage & line-stage) they recommend at least a 5 inches clearance from the top cover of the equipment.
Hope this helps,
Mondial
Your cabinet back is pegboard- you can easily cut a hole directly behind the amp location for a small fan. The fan would be hidden from site by the amp in front of it. Orient the fan so that it draws air in from the front, across the output tubes, and exhausts hot air behind the cabinet. Connect the fan to a switched power strip that you can place on the floor at the cabinet side. Turn on and off when you use your system.
you are currently violating ARC's recommendation for cooling of the VT60.
Read the section in "installation". Output tubes really need unobstructed space above them.
Both of my tube amps sit on amp stands with nothing above them but the ceiling. That is really a very tight space for an amp that probably generates a lot of heat..... not only from the tubes, but from the power transformer as well. Relocating the amp to the top of the unit would work nicely for ventilation plus free up space for future components below. However, that might leave you with a handful of IC's that are now too short. Also not sure on the height of the unit for all practical purposes. Aside from relocating the amp, cooling fans, like others have mentioned, might be your best shot.
If the amp is in free air the temperature of the amp would reach some point and stabilise. But in your case the heat may build up since it is enclosed. Even the tube case that it originally came in is vented on all sides. Your cabinet space is fairly large but only checking actual temperatures over a period time will let you know if you have a problem. Heat causes a slow deterioration of parts and tubes and for the best longevity running your tube equipment in the coolest environment is best.
...but I don't know what number I am looking for if I did. The aluminum sheet I have above it gets hot to the touch like the cage did, but everything else does seem to stabilize.
Since you seem to be concerned, otherwise why post a message, try to check the free air temperature around the amp over time to see what it settles at. It will give you a better idea of the of how much heat the amp can dissipate into the surrounding area. You might find that the heat in the cabinet just increases over time in which case the amp will also progressively heat up since there will be less heat differential for the amp to dissipate. As others suggest a small noiseless fan blowing the hot air out is always a good idea for a tube amp that is operated in a cabinet.
Good Morning, Nuwave:
Three other things you can try aside form what's already been suggested.
1. Being that it looks like the top two shelves have some adjustability you can try moving the shelves lower and place the amp on the top shelf and the Meridian & Marantz on the lower two shelves instead as this may provide more room for ventilation.
2. Drill two holes in the insides of each of the vertical sides of the cabinet of the same size and depth (like the ones already there) to allow the shelf with the Marantz and the Meridian to be adjusted upwards (even though the clearance above these two components would be lessened. Hoepfully these two components do not need as much ventilation space to operate without overheating?
3. Replace the shelf with the Marantz with thinner shelf?
Sincerely,
Kingsley.
I already moved the shelves to be able to fit three components, with the most room being over the amp. The amp is on the bottom because it's almost 33 lbs. The clearance at the top is what I am more concerned with if I add the tube phono stage, or maybe even a tube pre down the road.
One last suggestion, Nuwave, but I don't know if you're willing to try.
1. Disconnect the Meridian Pre, move the Marantz to the top shelf, removed the middle shelf, and place the Meridian vertical-wise either to the left or to the right of the amp, and reconnect everything. I know it's not the most aesthetically pleasing sight but at least that will provide ample ventilation above the amp and warm/hot air rises and still allow the Meridian Pre to breath. (Plus you can use shorter interconnects between the Meridian and the Audio Research amp.)
Sincerely,
Kingsley.
12AX7s produce very little heat. Top shelf is fine for that phono amp.
I strongly agree with Sony6060's statement that 12AX7s do not dissipate enough heat to worry about. This the case with many other typical pre-amp tubes as well barring the big boys some use.
That said, if you decide to use a big tube pre-amp it could get toasty in there. My answer is ditch the rack! At that point, you have become a real tubophile, and need to treat your tubes with care. An audio rack typically has open sides, front and back. Good luck don't stress over the phono stage.
The amp well that's another story.
Wouldn't an open tube design, even with a shelf over it, be better ventilated than one in a metal enclosure with a few slots in the top? That's why I took the cover/cage off of my VT60 (plus it looks better).
These are the two versions Vacuum Tube Audio offers.
I have the covers off both my pre and power amps. Better indeed for the ventilation and I like to keep an eye on my tubes upon turn on.
The only times you would leave the covers on is if your equipment specifically has a fan in it to keep it cool. You need the covers on to create a wind tunnel otherwise the fan is pretty much useless.
Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
Is the peg board screwed to the back? Even though there are holes in it, removing it altogether would provide more air flow. Of course then you have to deal with hiding the cables.The other thing is make the shelves shallower, so they don't quite reach the back. I don't know if you would be comfortable cutting the antique shelves. Or the integrity of how the shelf sits on the pegs. But providing more space for a current of upward airflow at the rear would also help.
Cheers!
Jonesy
EDIT: I don't know the benefits of using tube dampers, coolers and rings. I have some for my signal tubes but they are still in the box. They have them for power tubes as well. That is another way to alleviate heat I would think. Then the journey of the whole tube damper debate.
"I know just enough to get into trouble. But not enough to get out of it."
Edits: 01/19/17
I was going to slice off a couple inches from the entire back so it wasn't as deep, but the top shelf is not as deep as the rest and the turntable barely fits the way it is. The peg board comes off, but like you said I like it for hiding the cables. I cut wider slots in it behind each shelf to run the cables.
IMO I would not worry about it. The aluminum plate keeps heat off of the wood cabinet & tubes have enough air circulation. Heating from the 6550 tubes would be less than a 40 watt light bulb. That is not super hot.
Edits: 01/19/17
You could use a small fan. Some AC fans are very quiet. It does not need a huge volume of airflow to remove the heat. I use a 240V fan running on 120V, it works fine and is not audible.
there is a way to rig up a fan that turns on along with the amp? Plus I don't know how to wire a computer fan to run off of an ac outlet.
Antec makes many small nearly silent computer fans. All you need is a 12 VDC wall wart.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
Do I just splice them into the wall wart cord? Can I run two off of one wart? I would throw a switch on it too and turn them on when I turn on the amp.
Yes, splice into wall wart cord.
Yes, you can run two off one wart. I run three of them, though don't remember how much power my particular wart produces.
Switch - fine.
The ones I use are the Truequiet 120, though without lights. On low, I can just hear them from about a foot, no farther. At that speed, they don't move much air, but the small continuous air flow makes a big difference. I keep one on top of my VTL preamp, and used the others when I had the power amps in a confined shelf.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
Actually, most computer fans run on DC. AC Small AC fans are available, though. Here is one I have used:
How do I rig up something like that? I saw a posting where a person said they used a 12v vdc wall wart and they wired it to that. Could I splice two fans into one of those, and maybe add a power switch inline to turn it on and off? And I could put the switch near my amp somewhere.
The phono stage should be ok as long as you use only small signal tubes, however the amp in your photo needs better ventilation. You might consider removing the doors and put the amp on the bottom shelf or installing a computer type pancake fan on the back panel of the shelf.
I figure the amp already has better ventilation than it was designed for, since I removed the cage/cover and put a panel over the circuit boards. I could at a fan somewhere.
Yes, you should worry about the heat with so little open space above the power tubes. There don't appear to be any solutions, except for removing a shelf.
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